7 Series FPGAs Integrated Block for PCI Express v3.1 LogiCORE IP

7 Series FPGAs Integrated Block for PCI Express v3.1 LogiCORE IP
7 Series FPGAs
Integrated Block for
PCI Express v3.1
LogiCORE IP Product Guide
Vivado Design Suite
PG054 July 2, 2015
Table of Contents
IP Facts
Chapter 1: Overview
Feature Summary. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5
Applications . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6
Licensing and Ordering Information . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6
Chapter 2: Product Specification
Standards Compliance . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8
Resource Utilization. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9
Minimum Device Requirements . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10
Core Interfaces . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11
Transaction Interface. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14
PCI Configuration Space . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 39
Chapter 3: Designing with the Core
General Design Guidelines . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 46
Tandem Configuration . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 154
Clocking. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 182
Resets . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 185
Protocol Layers. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 186
Shared Logic . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 188
FPGA Configuration . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 195
Chapter 4: Design Flow Steps
Customizing and Generating the Core . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Constraining the Core . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Simulation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Synthesis and Implementation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
204
240
259
262
Chapter 5: Detailed Example Designs
Integrated Block Endpoint Configuration Overview . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 263
Programmed Input/Output: Endpoint Example Design . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 266
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Configurator Example Design . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Generating the Core. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Simulating the Example Design. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Synthesizing and Implementing the Example Design . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Directory and File Contents. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
280
286
289
290
291
Chapter 6: Test Benches
Root Port Model Test Bench for Endpoint . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 301
Endpoint Model Test Bench for Root Port . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 313
Appendix A: Migrating and Upgrading
Migrating to the Vivado Design Suite. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 316
Upgrading in the Vivado Design Suite . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 328
Appendix B: Debugging
Finding Help on Xilinx.com . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Debug Tools . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Simulation Debug. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Hardware Debug . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
329
331
334
337
Appendix C: Managing Receive-Buffer Space for Inbound Completions
General Considerations and Concepts . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 351
Methods of Managing Completion Space . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 352
Appendix D: PCIE_2_1 Port Descriptions
Clock and Reset Interface . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Transaction Layer Interface. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Block RAM Interface . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
GTX Transceiver Interface . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Configuration Management Interface . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Dynamic Reconfiguration Port Interface . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
TL2 Interface Ports . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
358
359
363
364
371
395
396
Appendix E: Additional Resources and Legal Notices
Xilinx Resources . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
References . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Revision History . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Please Read: Important Legal Notices . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
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398
398
399
401
3
IP Facts
Introduction
The 7 Series FPGAs Integrated Block for PCI
Express® core is a scalable, high-bandwidth,
and reliable serial interconnect building block
for use with Xilinx® Zynq®-7000 All
Programmable SoC, and 7 series FPGA families.
The 7 Series Integrated Block for PCI Express
(PCIe®) solution supports 1-lane, 2-lane,
4-lane, and 8-lane Endpoint and Root Port
configurations at up to 5 Gb/s (Gen2) speeds,
all of which are compliant with the PCI Express
Base Specification, rev. 2.1. This solution
supports the AMBA® AXI4-Stream interface for
the customer user interface.
With higher bandwidth per pin, low overhead,
low latency, reduced signal integrity issues, and
CDR architecture, the 7 Series Integrated Block
for PCIe sets the industry standard for a
high-performance, cost-efficient,
third-generation I/O solution.
•
Compliant with PCI/PCI Express power
management functions, and transaction
ordering rules
•
Supports a maximum transaction payload
of up to 1024 bytes
•
Supports Multi-Vector MSI for up to 32
vectors and MSI-X
•
Up-configure capability enables application
driven bandwidth scalability
LogiCORE IP Facts Table
Core Specifics
Supported
Device
Family (1)
Supported
User Interfaces
AXI4-Stream
Resource Utilization
Resources
Provided with Core
Verilog/VHDL(2) RTL Source
and Simulation Models
Design Files
Features
•
High-performance, highly flexible, scalable,
and reliable, general-purpose I/O core
•
Incorporates Xilinx Smart-IP technology to
guarantee critical timing
•
Uses GTXE2 or GTPE2 transceivers for 7 series
FPGA families
Example
Design
Verilog, VHDL
Test Bench
Verilog, VHDL
Constraints
File
XDC
Simulation
Model
Verilog, VHDL
Supported
S/W Driver
N/A
°
2.5 GT/s and 5.0 GT/s line speeds
°
Supports 1-lane, 2-lane, 4-lane, and
8-lane operation
Design Entry
°
Elastic buffers and clock compensation
Simulation
°
Automatic clock data recovery
Tested Design Flows(3)
Vivado® Design Suite
For a list of supported simulators, see the
Xilinx Design Tools: Release Notes Guide
Synthesis
•
Supports Endpoint and Root Port
configurations
•
8B/10B encode and decode
•
Supports Lane Reversal and Lane Polarity
Inversion per PCI Express specification
requirements
•
Standardized user interface
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Vivado Synthesis
Support
Provided by Xilinx @ www.xilinx.com/support
Notes:
1. For a complete listing of supported devices, see the Vivado
IP catalog.
2. RTL source for the GTX wrapper is Verilog only. VHDL projects
require mixed language mode simulators.
3. For the supported versions of the tools, see the
Xilinx Design Tools: Release Notes Guide.
www.xilinx.com
4
Product Specification
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Chapter 1
Overview
Xilinx® 7 series FPGAs include three unified FPGA families that are all designed for lowest
power to enable a common design to scale across families for optimal power, performance,
and cost. The Artix®-7 family is optimized for lowest cost and absolute power for the
highest volume applications. The Virtex®-7 family is optimized for highest system
performance and capacity. The Kintex®-7 family is an innovative class of FPGAs optimized
for the best price to performance. This document describes the function and operation of
the 7 Series FPGAs Integrated Block for PCI Express® core, including how to design,
customize, and implement it.
The 7 Series FPGAs Integrated Block for PCI Express core is a reliable, high-bandwidth,
scalable serial interconnect building block. The core instantiates the 7 Series Integrated
Block for PCI Express found in the 7 series FPGAs, and supports both Verilog and VHDL. This
core simplifies the design process and reduces time to market. It is configurable for
Endpoint and Root Port applications. This solution can be used in communication,
multimedia, server and mobile platforms and enables applications such as high-end
medical imaging, graphics intensive video games, DVD quality streaming video on the
desktop, and 10 Gigabit Ethernet interface cards.
Although the core is a fully verified solution, the challenge associated with implementing a
complete design varies depending on the configuration and functionality of the
application.
RECOMMENDED: For the best results, previous experience building high-performance, pipelined FPGA
designs using Xilinx implementation software and constraints files is recommended.
Feature Summary
The 7 Series Integrated Block for PCIe follows the PCI Express Base Specification, rev. 2.1
[Ref 2] layering model, which consists of the Physical, Data Link, and Transaction Layers. The
protocol uses packets to exchange information between layers. Packets are formed in the
Transaction and Data Link Layers to carry information from the transmitting component to
the receiving component. Necessary information is added to the packet being transmitted,
which is required to handle the packet at specific layers.
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Chapter 1: Overview
The functions of the protocol layers include:
•
Generating and processing of transaction layer packets (TLPs)
•
Flow-control management
•
Initialization and power management functions
•
Data protection
•
Error checking and retry functions
•
Physical link interface initialization
•
Maintenance and status tracking
•
Serialization, deserialization, and other circuitry for interface operation
Applications
The Xilinx 7 series FPGAs Integrated Block for PCI Express architecture enables a broad
range of computing and communications target applications, emphasizing performance,
cost, scalability, feature extensibility and mission-critical reliability. Typical applications
include:
•
Data communications networks
•
Telecommunications networks
•
Broadband wired and wireless applications
•
Cross-connects
•
Network interface cards
•
Chip-to-chip and backplane interconnect
•
Crossbar switches
•
Wireless base stations
Licensing and Ordering Information
This Xilinx LogiCORE IP module is provided at no additional cost with the Xilinx Vivado®
Design Suite under the terms of the Xilinx End User License. Information about this and
other Xilinx LogiCORE IP modules is available at the Xilinx Intellectual Property page. For
information about pricing and availability of other Xilinx LogiCORE IP modules and tools,
contact your local Xilinx sales representative.
For more information, visit the 7 Series FPGAs Integrated Block for PCI Express product
page.
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Chapter 2
Product Specification
The 7 Series FPGAs Integrated Block for PCI Express® contains full support for 2.5 Gb/s and
5.0 Gb/s PCI Express Endpoint and Root Port configurations. For 8.0 Gb/s (Gen3) support,
see Virtex-7 FPGA Gen3 Integrated Block for PCI Express Product Guide (PG023) [Ref 4] for
device support and information on the Virtex®-7 FPGA Gen3 Integrated Block for PCI
Express.
Table 2-1 defines the Integrated Block for PCIe® solutions.
Table 2-1:
Product Overview
Product Name
User Interface Width
Supported Lane Widths
1-lane at 2.5 Gb/s, 5.0 Gb/s
64
x1
2-lane at 2.5 Gb/s, 5.0 Gb/s
64
x1, x2(1)
4-lane at 2.5 Gb/s, 5.0 Gb/s
64, 128
x1, x2, x4 (1),(2)
8-lane at 2.5 Gb/s, 5.0 Gb/s
64, 128
x1, x2, x4, x8(1),(3)
Notes:
1. See Link Training: 2-Lane, 4-Lane, and 8-Lane Components, page 141 for additional information.
2. The x4 at 2.5 Gb/s option in the Vivado® IP catalog provides only the 64-bit width interface.
3. x8 at 5.0 Gb/s only available in the 128-bit width interface.
The Xilinx 7 Series FPGAs Integrated Block for PCI Express core internally instantiates the
7 Series FPGAs Integrated Block for PCI Express (PCIE_2_1). The integrated block follows the
PCI Express Base Specification layering model, which consists of the Physical, Data Link, and
Transaction layers. The integrated block is compliant with the PCI Express Base Specification,
rev. 2.1 [Ref 2].
Figure 2-1 illustrates these interfaces to the 7 Series FPGAs Integrated Block for PCI Express
core:
•
System (SYS) interface
•
PCI Express (PCI_EXP) interface
•
Configuration (CFG) interface
•
Transaction interface (AXI4-Stream)
•
Physical Layer Control and Status (PL) interface
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Chapter 2: Product Specification
The core uses packets to exchange information between the various modules. Packets are
formed in the Transaction and Data Link Layers to carry information from the transmitting
component to the receiving component. Necessary information is added to the packet
being transmitted, which is required to handle the packet at those layers. At the receiving
end, each layer of the receiving element processes the incoming packet, strips the relevant
information and forwards the packet to the next layer.
As a result, the received packets are transformed from their Physical Layer representation to
their Data Link Layer and Transaction Layer representations.
X-Ref Target - Figure 2-1
LogiCORE IP 7 Series FPGAs
Integrated Block for PCI Express
TX
Block RAM
User
Logic
Physical Layer
Control and Status
Host
Interface
User
Logic
RX
Block RAM
AXI4-Stream
Interface
Physical
(PL)
7 Series FPGAs
Integrated Block for
PCI Express
(PCIE_2_1)
PCI Express
(PCI_EXP)
Transceivers
Configuration
(CFG)
Optional Debug
Optional Debug
(DRP)
System
(SYS)
Figure 2-1:
PCI
Express
Fabric
User Logic
Clock
and
Reset
Top-Level Functional Blocks and Interfaces
Standards Compliance
The 7 Series FPGAs Integrated Block for PCI Express is compliant with the PCI Express Base
Specification, rev. 2.1 [Ref 2].
The 7 Series Integrated Block for PCI Express solution is compatible with industry-standard
application form factors such as the PCI Express Card Electromechanical (CEM) v2.0 and the
PCI Industrial Computer Manufacturers Group (PICMG) 3.4 specifications [Ref 2].
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Chapter 2: Product Specification
Resource Utilization
Table 2-2 shows the resources for the core for Vivado® Design Suite implementations.
Table 2-2:
Resources Used
Interface
Configuration Width Lanes
LUT
FF
RX
TX
Buffers Buffers
Size (KB) Size (KB)
x1g1
64-bit
1
649
753
x2g1
64-bit
2
1008
1090
x4g1
64-bit
4
1733
1764
x8g1
64-bit
8
3268
3608
x8g1
128-bit
8
3325
3780
x1g2
64-bit
1
654
807
x2g2
64-bit
2
1006
1192
x4g2
64-bit
4
1775
1967
x4g2
128-bit
4
1867
2139
x8g2
128-bit
8
3415
3780
Table 2-3:
4 - 32
4 - 32
CMPS
(Bytes)
128-1024
Block
Clock
RAM MMCMs Buffers
2 - 16
1
5
BUFG Usage of the Standalone PCIe Core
Link Speed
(Gb/s)
Lane Width
Interface Width AXI - ST Interface Frequency BUFG Usage
(Bits)
(MHz)
(GTX)
2.5
x1
64
62.5
4/32
4/32
2.5
x1
64
125
3/32
3/32
5
x1
64
125
4/32
4/32
2.5
x2
64
125
3/32
3/32
2.5
x2
64
250
4/32
4/32
5
x2
64
125
4/32
4/32
5
x2
64
250
4/32
4/32
2.5
x4
64
125
3/32
3/32
2.5
x4
64
250
4/32
3/32
5
x4
64
250
4/32
4/32
5
x4
128
125
5/32
5/32
2.5
x8
64
250
4/32
NA
2.5
x8
128
125
4/32
NA
5
x8
128
250
5/32
NA
2.5
x1
64
250
4/32
4/32
5
x1
64
250
4/32
4/32
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(GTP)
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Chapter 2: Product Specification
Minimum Device Requirements
Table 2-4 lists the minimum device requirements for 7 Series Integrated Block for PCIe
configurations.
Table 2-4:
Core Configurations
Zynq®-7000
Devices
Speed
Grade
Kintex®-7
FPGAs
Artix®-7
FPGAs(5)
XC7A15T
XC7A35T
XC7A50T
XC7A75T
XC7A100T
XC7A200T
ZC7015(1)
ZC7030(2)
ZC7035(3)
ZC7045(3)
ZC7100(3)
XC7VX485T
XC7V585T
XC7V2000T
XC7K325T
XC7K355T
XC7K410T
XC7K420
XC7K480T
XCK7160T(4)
XC7K70T(4)
1
4
3
4 (6)
1
1
Gen1 (2.5 Gb/s)
1-4 or 1-8
1–8
1–8
1–8
1–8
1–4
Gen2 (5.0 Gb/s)
1-4 or 1-8
1–8
1–8
1–8
1–8
1–4
Gen3 (8.0 Gb/s)(7)
—
—
—
—
—
—
x1–x4 Gen1
-1, -2, -3, -2L
-1, -2, -3, -2L
-1, -2, -3, -2L
-1, -2, -2L
-1, -2, -3, -2L
-1, -2, -3,
-2L
x8 Gen1
-1, -2, -3, -2L
-1, -2, -3, -2L
-1, -2, -3, -2L
-1, -2, -2L
-1, -2, -3, -2L
NA
x1–x4 Gen2
-1, -2, -3,
-2L (1V)
-1, -2, -3,
-2L (1V)
-1, -2, -3,
-2L (1V)
-1, -2, -2L (1V)
-1, -2, -3,
-2L (1V)
-2, -3 (1V)
x8 Gen2
-2, -3, -2L (1V)
-2, -3, -2L (1V)
-2, -3, -2L (1V)
-2, -2L (1V)
-2, -3, -2L (1V)
NA
Number of Integrated Blocks
for PCIe (see Table 4-6)
Lanes
Virtex®-7 FPGAs
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Chapter 2: Product Specification
Table 2-4:
Core Configurations (Cont’d)
Zynq®-7000
Devices
Maximum
Payload
Size MPS
(Bytes)
Virtex®-7 FPGAs
Kintex®-7
FPGAs
Artix®-7
FPGAs(5)
XC7A15T
XC7A35T
XC7A50T
XC7A75T
XC7A100T
XC7A200T
ZC7015(1)
ZC7030(2)
ZC7035(3)
ZC7045(3)
ZC7100(3)
XC7VX485T
XC7V585T
XC7V2000T
XC7K325T
XC7K355T
XC7K410T
XC7K420
XC7K480T
XCK7160T(4)
XC7K70T(4)
Gen1
1024
1024
1024
1024
1024
1024
x1–x4 Gen2
-2L (1V)
-2L (1V)
-2L (1V)
-2L (1V)
-2L (1V)
-2L (1V)
512 (-3)(10)
512 (-3)
256 (-2, -2L
(1V))
512 (-3)
256 (-2, -2L
(1V))
512 (-3)
256 (-2, -2L
(1V))
512 (-3)
256 (-2, -2L
(1V))
NA
x8 Gen2
256 (-2, -2L
(1V))
Notes:
1. ZC7015 device supports only up to Gen1 speed for -1 speed grades. For other speed grades, the maximum link speed
supported is Gen2 and link width is x4.
2. ZC7030 device supports max link width upto x4 and link speed Gen2.
3. ZC7035,ZC7045 and ZC7100 devices support maximum x8 link width and Gen2 link speed for speed grades other than -1.
For speed grade -1, ZC7035,ZC7045 and ZC7100 devices support only Gen1 speeds when x8 link width is selected. For other
link widths, there is no such restriction.
4. Kintex-7 FBG484 package supports only x1, x2, and x4 operation; x8 is not supported.
5. Artix-7 devices only support x1, x2, and x4 operation.
6. There are four integrated blocks in XC7V2000T; however, due to the lack of bonded transceivers, not all four can be used.
See Table 4-6 for the number of blocks supported in specific packages.
7. The 7 Series FPGAs Integrated Block for PCI Express does not support the Gen3 operation. See Virtex-7 FPGA Gen3 Integrated Block
for PCI Express Product Guide (PG023) [Ref 4] , for device support and information on the Virtex-7 FPGA Gen3 Integrated Block for
PCI Express.
8. 1-4 lanes for 7030 devices, and 1-8 lanes for 7045 devices.
9. Not all SSI devices-PCIe/MMCM site pairs pass timing skew checks.
10.Minimum supported speed grade for the specified MPS value.
11.Gen2 line rate is not supported for -2L (0.9V).
Core Interfaces
The 7 Series FPGAs Integrated Block for PCI Express core includes top-level signal interfaces
that have sub-groups for the receive direction, transmit direction, and signals common to
both directions.
System Interface
The System (SYS) interface consists of the system reset signal (sys_rst_n) and the system
clock signal (sys_clk), as described in Table 2-5.
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Table 2-5:
System Interface Signals
Function
Signal Name
Direction
Description
System Reset
sys_rst_n
Input
Asynchronous signal. sys_rst_n must be asserted
for at least 1500 ns during power on and warm
reset operations.
System Clock
sys_clk
Input
Reference clock: Selectable frequency 100 MHz,
125 MHz, or 250 MHz.
Some 7 series devices do not have 3.3 V I/Os available. Therefore the appropriate level shift
is required to operate with these devices that contain only 1.8 V banks.
The system reset signal is an asynchronous input. The assertion of sys_rst_n causes a
hard reset of the entire core. The system reset signal is a 3.3 V signal.
The system input clock must be 100 MHz, 125 MHz, or 250 MHz, as selected in the
Vivado® IP catalog clock and reference signals.
PCI Express Interface
The PCI Express (PCI_EXP) interface consists of differential transmit and receive pairs
organized in multiple lanes. A PCI Express lane consists of a pair of transmit differential
signals (pci_exp_txp, pci_exp_txn) and a pair of receive differential signals
(pci_exp_rxp, pci_exp_rxn). The 1-lane core supports only Lane 0, the 2-lane core
supports lanes 0-1, the 4-lane core supports lanes 0-3, and the 8-lane core supports lanes
0-7. Transmit and receive signals of the PCI_EXP interface are defined in Table 2-6.
Table 2-6:
PCI Express Interface Signals for 1-, 2-, 4- and 8-Lane Cores
Lane
Number
Name
Direction
Description
pci_exp_txp0
Output
PCI Express Transmit Positive: Serial Differential Output 0 (+)
pci_exp_txn0
Output
PCI Express Transmit Negative: Serial Differential Output 0 (–)
pci_exp_rxp0
Input
PCI Express Receive Positive: Serial Differential Input 0 (+)
pci_exp_rxn0
Input
PCI Express Receive Negative: Serial Differential Input 0 (–)
pci_exp_txp0
Output
PCI Express Transmit Positive: Serial Differential Output 0 (+)
pci_exp_txn0
Output
PCI Express Transmit Negative: Serial Differential Output 0 (–)
pci_exp_rxp0
Input
PCI Express Receive Positive: Serial Differential Input 0 (+)
pci_exp_rxn0
Input
PCI Express Receive Negative: Serial Differential Input 0 (–)
1-Lane Cores
0
2-Lane Cores
0
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Table 2-6:
PCI Express Interface Signals for 1-, 2-, 4- and 8-Lane Cores (Cont’d)
Lane
Number
Name
Direction
Description
1
pci_exp_txp1
Output
PCI Express Transmit Positive: Serial Differential Output 1 (+)
pci_exp_txn1
Output
PCI Express Transmit Negative: Serial Differential Output 1 (–)
pci_exp_rxp1
Input
PCI Express Receive Positive: Serial Differential Input 1 (+)
pci_exp_rxn1
Input
PCI Express Receive Negative: Serial Differential Input 1 (–)
pci_exp_txp0
Output
PCI Express Transmit Positive: Serial Differential Output 0 (+)
pci_exp_txn0
Output
PCI Express Transmit Negative: Serial Differential Output 0 (–)
pci_exp_rxp0
Input
PCI Express Receive Positive: Serial Differential Input 0 (+)
pci_exp_rxn0
Input
PCI Express Receive Negative: Serial Differential Input 0 (–)
pci_exp_txp1
Output
PCI Express Transmit Positive: Serial Differential Output 1 (+)
pci_exp_txn1
Output
PCI Express Transmit Negative: Serial Differential Output 1 (–)
pci_exp_rxp1
Input
PCI Express Receive Positive: Serial Differential Input 1 (+)
pci_exp_rxn1
Input
PCI Express Receive Negative: Serial Differential Input 1 (–)
pci_exp_txp2
Output
PCI Express Transmit Positive: Serial Differential Output 2 (+)
pci_exp_txn2
Output
PCI Express Transmit Negative: Serial Differential Output 2 (–)
pci_exp_rxp2
Input
PCI Express Receive Positive: Serial Differential Input 2 (+)
pci_exp_rxn2
Input
PCI Express Receive Negative: Serial Differential Input 2 (–)
pci_exp_txp3
Output
PCI Express Transmit Positive: Serial Differential Output 3 (+)
pci_exp_txn3
Output
PCI Express Transmit Negative: Serial Differential Output 3 (–)
pci_exp_rxp3
Input
PCI Express Receive Positive: Serial Differential Input 3 (+)
pci_exp_rxn3
Input
PCI Express Receive Negative: Serial Differential Input 3 (–)
pci_exp_txp0
Output
PCI Express Transmit Positive: Serial Differential Output 0 (+)
pci_exp_txn0
Output
PCI Express Transmit Negative: Serial Differential Output 0 (–)
pci_exp_rxp0
Input
PCI Express Receive Positive: Serial Differential Input 0 (+)
pci_exp_rxn0
Input
PCI Express Receive Negative: Serial Differential Input 0 (–)
pci_exp_txp1
Output
PCI Express Transmit Positive: Serial Differential Output 1 (+)
pci_exp_txn1
Output
PCI Express Transmit Negative: Serial Differential Output 1 (–)
pci_exp_rxp1
Input
PCI Express Receive Positive: Serial Differential Input 1 (+)
pci_exp_rxn1
Input
PCI Express Receive Negative: Serial Differential Input 1 (–)
pci_exp_txp2
Output
PCI Express Transmit Positive: Serial Differential Output 2 (+)
pci_exp_txn2
Output
PCI Express Transmit Negative: Serial Differential Output 2 (–)
pci_exp_rxp2
Input
PCI Express Receive Positive: Serial Differential Input 2 (+)
pci_exp_rxn2
Input
PCI Express Receive Negative: Serial Differential Input 2 (–)
4-Lane Cores
0
1
2
3
8-Lane Cores
0
1
2
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Chapter 2: Product Specification
Table 2-6:
PCI Express Interface Signals for 1-, 2-, 4- and 8-Lane Cores (Cont’d)
Lane
Number
Name
Direction
Description
3
pci_exp_txp3
Output
PCI Express Transmit Positive: Serial Differential Output 3 (+)
pci_exp_txn3
Output
PCI Express Transmit Negative: Serial Differential Output 3 (–)
pci_exp_rxp3
Input
PCI Express Receive Positive: Serial Differential Input 3 (+)
pci_exp_rxn3
Input
PCI Express Receive Negative: Serial Differential Input 3 (–)
pci_exp_txp4
Output
PCI Express Transmit Positive: Serial Differential Output 4 (+)
pci_exp_txn4
Output
PCI Express Transmit Negative: Serial Differential Output 4 (–)
pci_exp_rxp4
Input
PCI Express Receive Positive: Serial Differential Input 4 (+)
pci_exp_rxn4
Input
PCI Express Receive Negative: Serial Differential Input 4 (–)
pci_exp_txp5
Output
PCI Express Transmit Positive: Serial Differential Output 5 (+)
pci_exp_txn5
Output
PCI Express Transmit Negative: Serial Differential Output 5 (–)
pci_exp_rxp5
Input
PCI Express Receive Positive: Serial Differential Input 5 (+)
pci_exp_rxn5
Input
PCI Express Receive Negative: Serial Differential Input 5 (–)
pci_exp_txp6
Output
PCI Express Transmit Positive: Serial Differential Output 6 (+)
pci_exp_txn6
Output
PCI Express Transmit Negative: Serial Differential Output 6 (–)
pci_exp_rxp6
Input
PCI Express Receive Positive: Serial Differential Input 6 (+)
pci_exp_rxn6
Input
PCI Express Receive Negative: Serial Differential Input 6 (–)
pci_exp_txp7
Output
PCI Express Transmit Positive: Serial Differential Output 7 (+)
pci_exp_txn7
Output
PCI Express Transmit Negative: Serial Differential Output 7 (–)
pci_exp_rxp7
Input
PCI Express Receive Positive: Serial Differential Input 7 (+)
pci_exp_rxn7
Input
PCI Express Receive Negative: Serial Differential Input 7 (–)
4
5
6
7
For more information about PCI Express clocking and reset, see PCI Express Clocking and
PCI Express Reset in the “Use Model” chapter of the 7 Series FPGAs GTX/GTH Transceivers
User Guide (UG476) [Ref 12].
Transaction Interface
The transaction interface provides a mechanism for the user design to generate and
consume transaction layer packets (TLPs). The signal names and signal descriptions for this
interface are shown in Table 2-7, Table 2-9, and Table 2-10.
Common Interface
Table 2-7 describes the common interface signals.
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Table 2-7:
Common Transaction Interface Signals
Name
Direction
Description
Output
Transaction Clock: Transaction, Configuration, and Physical Layer Control
and Status Interface operations are referenced to and synchronous with
the rising edge of this clock. This signal is active after power-on, and
sys_rst_n has no effect on it. This signal is guaranteed to be stable at
the selected operating frequency only after user_reset_out is deasserted.
The user_clk_out clock output is a fixed frequency configured in the
CORE Generator tool. This signal does not change frequencies in case of
link recovery or training down.
See Table 2-8 for recommended and optional frequencies.
Output
Transaction Reset: User logic interacting with the Transaction and
Configuration interfaces must use user_reset_out to return to its
quiescent state. This signal is deasserted synchronously with respect to
user_clk_out, and is deasserted and asserted asynchronously with
sys_rst_n assertion. This signal is asserted for core in-band reset
events such as Hot Reset or Link Disable.
user_lnk_up
Output
Transaction Link Up: Transaction link-up is asserted when the core and the
connected upstream link partner port are ready and able to exchange
data packets. Transaction link-up is deasserted when the core and link
partner are attempting to establish communication, or when
communication with the link partner is lost due to errors on the
transmission channel. This signal is also deasserted when the core is
driven to Hot Reset or Link Disable state by the link partner, and all TLPs
stored in the core are lost. This signal is not deasserted while in the
Recovery state, but is deasserted if Recovery fails.
fc_ph[7:0]
Output
Posted Header Flow Control Credits: The number of Posted Header FC
credits for the selected flow control type.
fc_pd[11:0]
Output
Posted Data Flow Control Credits: The number of Posted Data FC credits
for the selected flow control type.
fc_nph[7:0]
Output
Non-Posted Header Flow Control Credits: The number of Non-Posted
Header FC credits for the selected flow control type.
fc_npd[11:0]
Output
Non-Posted Data Flow Control Credits: The number of Non-Posted Data
FC credits for the selected flow control type.
fc_cplh[7:0]
Output
Completion Header Flow Control Credits: The number of Completion
Header FC credits for the selected flow control type.
fc_cpld[11:0]
Output
Completion Data Flow Control Credits: The number of Completion Data
FC credits for the selected flow control type.
Input
Flow Control Informational Select: Selects the type of flow control
information presented on the fc_* signals. Possible values are:
• 000: Receive buffer available space
• 001: Receive credits granted to the link partner
• 010: Receive credits consumed
• 100: Transmit user credits available
• 101: Transmit credit limit
• 110: Transmit credits consumed
user_clk_out
user_reset_out
fc_sel[2:0]
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Chapter 2: Product Specification
Table 2-8:
Recommended and Optional Transaction Clock (user_clk_out) Frequencies
Product
Link Speed
(Gb/s)
Interface Width(1)
(Bits)
Recommended
Frequency (MHz)
Optional
Frequency (MHz)
1-lane
2.5
64
62.5
125, 250
1-lane
5
64
62.5
125, 250
2-lane
2.5
64
62.5
125, 250
2-lane
5
64
125
250
4-lane
2.5
64
125
250
4-lane
5
64
250
-
4-lane
5
128
125
-
8-lane
2.5
64
250
-
8-lane
2.5
128
125
250
8-lane
5
128
250
-
Notes:
1. Interface width is a static selection and does not change with dynamic link speed changes.
Transmit Interface
Table 2-9 defines the transmit (TX) interface signals. The bus s_axis_tx_tuser consists
of unrelated signals. Both the mnemonics and TSUSER signals are used throughout this
document. For example, the Transmit Source Discontinue signal is referenced as:
(tsrc_dsc)s_axis_tx_tuser[3].
Table 2-9:
Transmit Interface Signals
Name
Mnemonic Direction
Description
s_axis_tx_tlast
Input
Transmit End-of-Frame (EOF): Signals the end of a packet. Valid
only along with assertion of s_axis_tx_tvalid.
s_axis_tx_tdata[W-1:0]
Input
Transmit Data: Packet data to be transmitted.
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Product
Data Bus Width
(W)
1-lane (2.5 Gb/s and 5.0 Gb/s)
64
2-lane (2.5 Gb/s and 5.0 Gb/s)
64
4-lane (2.5 Gb/s and 5.0 Gb/s)
64 or 128
8-lane (2.5 Gb/s and 5.0 Gb/s)
64 or 128
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Table 2-9:
Transmit Interface Signals (Cont’d)
Name
Mnemonic Direction
s_axis_tx_tkeep[7:0]
(64-bit interface)
Description
Input
Transmit Data Strobe: Determines which data bytes are valid on
s_axis_tx_tdata[W-1:0] during a given beat
(s_axis_tx_tvalid and s_axis_tx_tready both
asserted).
• Bit 0 corresponds to the least significant byte on
s_axis_tx_tdata.
• Bit 7 (64-bit) and bit 15 (128-bit) correspond to the most
significant byte.
For example:
• s_axis_tx_tkeep[0] ==1b, s_axis_tx_tdata[7:0] is valid
• s_axis_tx_tkeep[7] ==0b, s_axis_tx_tdata[63:56] is not valid
When s_axis_tx_tlast is not asserted, the only valid values
are 0xFF (64-bit) or 0xFFFF (128-bit).
When s_axis_tx_tlast is asserted, valid values are:
• 64-bit: only 0x0F and 0xFF are valid.
• 128-bit: 0x000F, 0x00FF, 0x0FFF, and 0xFFFF are valid.
s_axis_tx_tvalid
Input
Transmit Source Ready: Indicates that the user application is
presenting valid data on s_axis_tx_tdata.
s_axis_tx_tready
Output
Transmit Destination Ready: Indicates that the core is ready to
accept data on s_axis_tx_tdata. The simultaneous
assertion of s_axis_tx_tvalid and s_axis_tx_tready
marks the successful transfer of one data beat on
s_axis_tx_tdata.
Input
Transmit Source Discontinue: Can be asserted any time starting
on the first cycle after start-of-frame (SOF). Assert
s_axis_tx_tlast simultaneously with
(tx_src_dsc)s_axis_tx_tuser[3].
tx_buf_av[5:0]
Output
Transmit Buffers Available: Indicates the number of free
transmit buffers available in the core. Each free transmit buffer
can accommodate one TLP up to the supported maximum
payload size (MPS). The maximum number of transmit buffers is
determined by the supported MPS and block RAM
configuration selected. (See Core Buffering and Flow Control,
page 93.)
tx_err_drop
Output
Transmit Error Drop: Indicates that the core discarded a packet
because of a length violation or, when streaming, data was not
presented on consecutive clock cycles.
Input
Transmit Streamed: Indicates a packet is presented on
consecutive clock cycles and transmission on the link can begin
before the entire packet has been written to the core.
Commonly referred as transmit cut-through mode.
s_axis_tx_tkeep[15:0]
(128-bit interface)
s_axis_tx_tuser[3]
s_axis_tx_tuser[2]
tx_cfg_req
t_src_dsc
tx_str
Output
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Transmit Configuration Request: Asserted when the core is
ready to transmit a Configuration Completion or other
internally generated TLP.
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Table 2-9:
Transmit Interface Signals (Cont’d)
Name
Mnemonic Direction
tx_cfg_gnt
Description
Input
Transmit Configuration Grant: Asserted by the user application
in response to tx_cfg_req, to allow the core to transmit an
internally generated TLP. The tx_cfg_req signal is always
deasserted after the core-generated packet has been serviced
before another request is made. Therefore, user designs can
look for the rising edge of tx_cfg_req to determine when to
assert tx_cfg_gnt. Holding tx_cfg_gnt deasserted after
tx_cfg_req allows user-initiated TLPs to be given a higher
priority of transmission over core-generated TLPs. Asserting
tx_cfg_gnt for one clock cycle when tx_cfg_req is asserted
causes the next packet output to be the internally generated
packet of the core. In cases where there is no buffer space to
store the internal packet, tx_cfg_req remains asserted even
after tx_cfg_gnt has been asserted. Your design does not
need to assert tx_cfg_gnt again because the initial assertion
has been captured.
If you do not wish to alter the prioritization of the transmission
of internally generated TLPs, assert this signal continuously.
s_axis_tx_tuser[1]
tx_err_fwd
Input
Transmit Error Forward: This input marks the current packet in
progress as error-poisoned. It can be asserted any time
between SOF and EOF, inclusive. The tx_err_fwd signal must
not be asserted if (tx_str)s_axis_tx_tuser[2] is asserted.
s_axis_tx_tuser[0]
tx_ecrc_gen
Input
Transmit ECRC Generate: Causes the end-to-end cyclic
redundancy check (ECRC) digest to be appended. This input
must be asserted at the beginning of the TLP.
Receive Interface
Table 2-10 defines the receive (RX) interface signals. The bus m_axis_tx_tuser consists
of unrelated signals. Mnemonics for these signals are used throughout this document in
place of the TUSER signal names.
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Chapter 2: Product Specification
Table 2-10:
Receive Interface Signals
Name
Mnemonic
Direction
Description
m_axis_rx_tlast
Output
Receive End-of-Frame (EOF):
Signals the end of a packet. Valid only if
m_axis_rx_tvalid is also asserted.
The 128-bit interface does not use m_axis_rx_tlast
signal at all (tied Low), but rather it uses
m_axis_rx_tuser signals.
m_axis_rx_tdata[W-1:0]
Output
Receive Data:
Packet data being received. Valid only if
m_axis_rx_tvalid is also asserted.
When a Legacy Interrupt is sent from the Endpoint, the
ENABLE_MSG_ROUTE attribute should be set to
11'b00000001000 to see this signal toggling along
with m_axis_rx_tdata, m_axis_rx_tkeep and
m_axis_rx_tuser.
Product
Data Bus Width
(W)
1-lane (2.5 Gb/s and 5.0 Gb/s)
64
2-lane (2.5 Gb/s and 5.0 Gb/s)
64
4-lane (2.5 Gb/s and 5.0 Gb/s)
64 or 128
8-lane (2.5 Gb/s and 5.0 Gb/s)
64 or 128
128-bit interface only: Unlike the Transmit interface
s_axis_tx_tdata[127:0], received TLPs can begin
on either the upper QWORD
m_axis_rx_tdata[127:64] or lower QWORD
m_axis_rx_tdata[63:0] of the bus. See the
description of is_sof and (rx_is_sof[4:0])
m_axis_rx_tuser[14:10]
m_axis_rx_tuser[21:17] for further explanation.
m_axis_rx_tkeep[7:0]
(64-bit interface only)
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Output
Receive Data Strobe:
Determines which data bytes are valid on
m_axis_rx_tdata[63:0] during a given beat
(m_axis_rx_tvalid and m_axis_rx_tready both
asserted).
Bit 0 corresponds to the least significant byte on
m_axis_rx_tdata and bit 7 correspond to the most
significant byte, for example:
• m_axis_rx_tkeep[0] == 1b,
m_axis_rx_tdata[7:0] is valid
• m_axis_rx_tkeep[7] == 0b,
m_axis_rx_tdata[63:56] is not valid
When m_axis_rx_tlast is not asserted, the only valid
value is 0xFF.
When m_axis_rx_tlast is asserted, valid values are:
• 64-bit: Only 0x0F and 0xFF are valid
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Chapter 2: Product Specification
Table 2-10:
Receive Interface Signals (Cont’d)
Name
Mnemonic
Direction
Description
m_axis_rx_tuser[14:10]
(128-bit interface only)
rx_is_sof[4:0]
Output
Indicates the start of a new packet header in
m_axis_rx_tdata:
• Bit 4: Asserted when a new packet is present
• Bit 0-3: Indicates byte location of start of new packet,
binary encoded
Valid values:
• 5'b10000 = SOF at AXI byte 0 (DWORD 0)
m_axis_rx_tdata[7:0]
• 5'b11000 = SOF at AXI byte 8 (DWORD 2)
m_axis_rx_tdata[71:64]
• 5'b00000 = No SOF present
m_axis_rx_tuser[21:17]
(128-bit interface only)
rx_is_eof[4:0]
Output
Indicates the end of a packet in m_axis_rx_tdata:
• Bit 4: Asserted when a packet is ending
• Bit 0-3: Indicates byte location of end of the packet,
binary encoded
Valid values:
• 5'b10011 = EOF at AXI byte 3 (DWORD 0)
m_axis_rx_tdata[31:24]
• 5'b10111 = EOF at AXI byte 7 (DWORD 1)
m_axis_rx_tdata[63:56]
• 5'b11011 = EOF at AXI byte 11 (DWORD 2)
m_axis_rx_tdata[95:88]
• 5'b11111 = EOF at AXI byte 15 (DWORD 3)
m_axis_rx_tdata[127:120]
• 5'b01111 = No EOF present
m_axis_rx_tuser[1]
rx_err_fwd
Output
Receive Error Forward:
• 64-bit interface: When asserted, marks the packet in
progress as error-poisoned. Asserted by the core for
the entire length of the packet.
• 128-bit interface: When asserted, marks the current
packet in progress as error-poisoned. Asserted by the
core for the entire length of the packet. If asserted
during a straddled data transfer, applies to the packet
that is beginning.
m_axis_rx_tuser[0]
rx_ecrc_err
Output
Receive ECRC Error: Indicates the current packet has an
ECRC error. Asserted at the packet EOF.
Output
Receive Source Ready: Indicates that the core is
presenting valid data on m_axis_rx_tdata.
m_axis_rx_tvalid
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Table 2-10:
Receive Interface Signals (Cont’d)
Name
Direction
Description
m_axis_rx_tready
Input
Receive Destination Ready: Indicates that the user
application is ready to accept data on
m_axis_rx_tdata. The simultaneous assertion of
m_axis_rx_tvalid and m_axis_rx_tready marks
the successful transfer of one data beat on
s_axis_tx_tdata.
For a Root port configuration, when a Legacy Interrupt is
sent from the Endpoint, the ENABLE_MSG_ROUTE
attribute should be set to 11'b00000001000 to see this
signal toggling along with m_axis_rx_tdata,
m_axis_rx_tkeep and m_axis_rx_tuser.
rx_np_ok
Input
Receive Non-Posted OK: The user application asserts this
signal when it is ready to accept Non-Posted Request
TLPs. rx_np_ok must be deasserted when the user
application cannot process received Non-Posted TLPs, so
that these can be buffered within the receive queue of the
core. In this case, Posted and Completion TLPs received
after the Non-Posted TLPs bypass the blocked TLPs.
When the user application approaches a state where it is
unable to service Non-Posted Requests, it must deassert
rx_np_ok two clock cycle before the core asserts
m_axis_rx_tlast of the next-to-last Non-Posted TLP
the user application can accept.
rx_np_req
Input
Receive Non-Posted Request: When asserted, requests
one non-posted TLP from the core per user_clk cycle.
If the user application can process received Non-Posted
TLPs at the line rate, this signal can be constantly
asserted. If the user application is not requesting
Non-Posted packets, received Posted and Completion
TLPs bypass waiting Non-Posted TLPs.
Output
Receive BAR Hit: Indicates BAR(s) targeted by the current
receive transaction. Asserted from the beginning of the
packet to m_axis_rx_tlast.
• (rx_bar_hit[0])m_axis_rx_tuser[2]: BAR0
• (rx_bar_hit[1])m_axis_rx_tuser[3]: BAR1
• (rx_bar_hit[2])m_axis_rx_tuser[4]: BAR2
• (rx_bar_hit[3])m_axis_rx_tuser[5]: BAR3
• (rx_bar_hit[4])m_axis_rx_tuser[6]: BAR4
• (rx_bar_hit[5])m_axis_rx_tuser[7]: BAR5
• (rx_bar_hit[6])m_axis_rx_tuser[8]: Expansion ROM
Address
If two BARs are configured into a single 64-bit address,
both corresponding rx_bar_hit bits are asserted.
• m_axis_rx_tuser[8:4] are not applicable to Root
Port configurations.
• m_axis_rx_tuser[9] is reserved for future use.
m_axis_rx_tuser[9:2]
Mnemonic
rx_bar_hit[7:0]
m_axis_rx_tuser[16:15]
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Reserved
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Chapter 2: Product Specification
Physical Layer Interface
The Physical Layer (PL) interface enables the user design to inspect the status of the Link
and Link Partner and control the Link State. Table 2-11 describes the signals for the PL
interface.
Table 2-11:
Physical Layer Interface Signals
Name
Direction
Description
pl_initial_link_width[2:0]
Output
Initial Negotiated Link Width: Indicates the link width after the
PCI Express port has achieved the first successful link training.
Initial Negotiated Link Width represents the widest link width
possible during normal operation of the link, and can be equal to
or smaller than the capability link width (smaller of the two)
supported by link partners. This value is reset when the core is
reset or the LTSSM goes through the Detect state. Otherwise the
value remains the same.
• 000: Link not trained
• 001: 1-Lane link
• 010: 2-Lane link
• 011: 4-Lane link
• 100: 8-Lane link
pl_phy_lnk_up
Output
Physical Layer Link Up Status: Indicates the physical layer link up
status.
pl_lane_reversal_mode[1:0]
Output
Lane Reversal Mode: Indicates the current Lane Reversal mode.
• 00: No reversal
• 01: Lanes 1:0 reversed
• 10: Lanes 3:0 reversed
• 11: Lanes 7:0 reversed
pl_link_gen2_cap
Output
Link Gen2 Capable: Indicates that the PCI Express link is 5.0 Gb/s
(Gen 2) speed capable (both the Link Partner and the Device are
Gen 2 capable)
• 0: Link is not Gen2 Capable
• 1: Link is Gen2 Capable
pl_link_partner_gen2_supported
Output
Link Partner Gen2 Capable: Indicates if the PCI Express link
partner advertises 5.0 Gb/s (Gen2) capability. Valid only when
user_lnk_up is asserted.
• 0: Link partner not Gen2 capable
• 1: Link partner is Gen2 capable
pl_link_upcfg_cap
Output
Link Upconfigure Capable: Indicates the PCI Express link is
Upconfigure capable. Valid only when user_lnk_up is asserted.
• 0: Link is not Upconfigure capable
• 1: Link is Upconfigure capable
pl_sel_lnk_rate
Output
Current Link Rate: Reports the current link speed. Valid only when
user_lnk_up is asserted.
• 0: 2.5 Gb/s
• 1: 5.0 Gb/s
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Chapter 2: Product Specification
Table 2-11:
Physical Layer Interface Signals (Cont’d)
Name
Direction
Description
pl_sel_lnk_width[1:0]
Output
Current Link Width: Reports the current link width. Valid only
when user_lnk_up is asserted.
• 00: 1-Lane link
• 01: 2-Lane link
• 10: 4-Lane link
• 11: 8-Lane link
pl_ltssm_state[5:0]
Output
LTSSM State: Shows the current LTSSM state (hex).
• 0, 1: Detect Quiet
• 2, 3: Detect Active
• 4: Polling Active
• 5: Polling Configuration
• 6: Polling Compliance, Pre_Send_EIOS
• 7: Polling Compliance, Pre_Timeout
• 8: Polling Compliance, Send_Pattern
• 9: Polling Compliance, Post_Send_EIOS
• A: Polling Compliance, Post_Timeout
• B: Configuration Linkwidth, State 0
• C: Configuration Linkwidth, State 1
• D: Configuration Linkwidth, Accept 0
• E: Configuration Linkwidth, Accept 1
• F: Configuration Lanenum Wait
• 10: Configuration Lanenum, Accept
• 11: Configuration Complete x1
• 12: Configuration Complete x2
• 13: Configuration Complete x4
• 14: Configuration Complete x8
• 15: Configuration Idle
• 16: L0
• 17: L1 Entry0
• 18: L1 Entry1
• 19: L1 Entry2 (also used for the L2/L3 Ready pseudo state)
• 1A: L1 Idle
• 1B: L1 Exit
• 1C: Recovery Rcvrlock
• 1D: Recovery Rcvrcfg
• 1E: Recovery Speed_0
• 1F: Recovery Speed_1
• 20: Recovery Idle
• 21: Hot Reset
• 22: Disabled Entry 0
• 23: Disabled Entry 1
• 24: Disabled Entry 2
• 25: Disabled Idle
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Chapter 2: Product Specification
Table 2-11:
Physical Layer Interface Signals (Cont’d)
Name
Direction
Description
pl_ltssm_state[5:0] (Cont’d)
Output
•
•
•
•
•
•
•
•
•
•
•
•
•
•
pl_rx_pm_state[1:0]
Output
RX Power Management State: Indicates the RX Power
Management State:
• 00: RX Not in L0s
• 01: RX L0s Entry
• 10: RX L0s Idle
• 11: RX L0s FTS
pl_tx_pm_state[2:0]
Output
TX Power Management State: Indicates the TX Power
Management State:
• 000: TX not in L0s
• 001: TX L0s Entry0
• 010: TX L0s Entry1
• 011: TX L0s Entry2
• 100: TX L0s Idle
• 101: TX L0s FTS0
• 110: TX L0s FTS1
• 111: TX L0s FTS2
pl_directed_link_auton
Input
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27: Root Port, Configuration, Linkwidth State 1
28: Root Port, Configuration, Linkwidth State 2
29: Root Port, Configuration, Link Width Accept 0
2A: Root Port, Configuration, Link Width Accept 1
2B: Root Port, Configuration, Lanenum_Wait
2C: Root Port, Configuration, Lanenum_Accept
2D: Timeout To Detect
2E: Loopback Entry0
2F: Loopback Entry1
30: Loopback Active0
31: Loopback Exit0
32: Loopback Exit1
33: Loopback Master Entry0
Directed Autonomous Link Change: Specifies the reason for
directed link width and speed change. This must be used in
conjunction with pl_directed_link_change[1:0],
pl_directed_link_speed, and
pl_directed_link_width[1:0] inputs.
• 0: Link reliability driven
• 1: Application requirement driven (autonomous)
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Chapter 2: Product Specification
Table 2-11:
Physical Layer Interface Signals (Cont’d)
Name
Direction
Description
pl_directed_link_change[1:0]
Input
Directed Link Change Control: Directs the PCI Express Port to
initiate a link width and/or speed change. Link change operation
must be initiated when user_lnk_up is asserted. For a Root
Port, pl_directed_link_change must not be set to 10 or 11
unless the attribute RP_AUTO_SPD = 11.
• 00: No change
• 01: Link width
• 10: Link speed
• 11: Link width and speed (level-triggered)
pl_directed_link_speed
Input
Directed Target Link Speed: Specifies the target link speed for a
directed link change operation, in conjunction with the
pl_directed_link_change[1:0] input. The target link
speed must not be set High unless the
pl_link_gen2_capable output is High.
• 0: 2.5 Gb/s
• 1: 5.0 Gb/s
pl_directed_link_width[1:0]
Input
Directed Target Link Width: Specifies the target link width for a
directed link change operation, in conjunction with
pl_directed_link_change[1:0] input.
Encoding Target Link Width:
• 00: 1-Lane link
• 01: 2-Lane link
• 10: 4-Lane link
• 11: 8-Lane link
pl_directed_change_done
Output
Directed Link Change Done: Indicates to the user application that
the directed link speed change or directed link width change is
done.
Input
Endpoint Preferred Transmitter De-emphasis: Enables the
Endpoint to control de-emphasis used on the link at 5.0 Gb/s
speeds. pl_upstream_prefer_deemph can be changed in
conjunction with pl_directed_link_speed and
pl_directed_link_change[1:0] inputs when transitioning
from 2.5 Gb/s to 5.0 Gb/s data rates. Value presented on
pl_upstream_prefer_deemph depends upon the property of
PCI Express physical interconnect channel in use.
• 0: –6 dB de-emphasis recommended for short, reflection
dominated channels.
• 1: –3.5 dB de-emphasis recommended for long, loss dominated
channels.
pl_upstream_prefer_deemph
Table 2-12:
Role-Specific Physical Layer Interface Signals: Endpoint
Name
pl_received_hot_rst
Direction
Description
Output
Hot Reset Received: Indicates that an in-band hot reset command
has been received.
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Chapter 2: Product Specification
Table 2-13:
Role-Specific Physical Layer Interface Signals: Root Port
Name
Direction
Description
pl_transmit_hot_rst
Input
Transmit Hot Reset: Active-High. Directs the PCI Express
port to transmit an in-band hot reset.
pl_transmit_hot_rst input port must be asserted
until pl_ltssm_state is 6'h21 (in the hot reset state).
Once it enters the hot reset state,
pl_transmit_hot_rst input can be deasserted to
allow the link to retrain.
pl_downstream_deemph_source
Input
Root Port Preferred Transmitter De-emphasis: Enables the
Root Port to control de-emphasis used on the link at
5.0 Gb/s speeds.
• 0: Use Upstream link partner preferred de-emphasis.
• 1: Use Selectable de-emphasis value from Link Control
2 register.
Configuration Interface
The Configuration (CFG) interface enables the user design to inspect the state of the
Endpoint for PCIe configuration space. The user design provides a 10-bit configuration
address, which selects one of the 1024 configuration space doubleword (DWORD) registers.
The Endpoint returns the state of the selected register over the 32-bit data output port.
Table 2-14 defines the Configuration interface signals. See Designing with Configuration
Space Registers and Configuration Interface, page 105 for usage.
Table 2-14:
Configuration Interface Signals
Name
Direction
Description
cfg_mgmt_do[31:0]
Output
Configuration Data Out: A 32-bit data output port used to
obtain read data from the configuration space inside the core.
cfg_mgmt_rd_wr_done
Output
Configuration Read Write Done: Read-write done signal
indicates a successful completion of the user configuration
register access operation.
• For a user configuration register read operation, this signal
validates the cfg_mgmt_do[31:0] data-bus value.
• For a user configuration register write operation, the
assertion indicates completion of a successful write
operation.
cfg_mgmt_di[31:0]
Input
Configuration Data In: A 32-bit data input port used to
provide write data to the configuration space inside the core.
cfg_mgmt_dwaddr[9:0]
Input
Configuration DWORD Address: A 10-bit address input port
used to provide a configuration register DWORD address
during configuration register accesses.
cfg_mgmt_byte_en[3:0]
Input
Configuration Byte Enable: Byte enables for configuration
register write access.
cfg_mgmt_wr_en
Input
Configuration Write Enable: Write enable for configuration
register access.
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Chapter 2: Product Specification
Table 2-14:
Configuration Interface Signals (Cont’d)
Name
Direction
Description
cfg_mgmt_rd_en
Input
Configuration Read Enable: Read enable for configuration
register access.
cfg_mgmt_wr_readonly
Input
Management Write Readonly Bits: Write enable to treat any
ReadOnly bit in the current Management Write as a RW bit,
not including bits set by attributes, reserved bits, and status
bits.
cfg_status[15:0]
Output
Configuration Status: Status register from the Configuration
Space Header. Not supported.
cfg_command[15:0]
Output
Configuration Command: Command register from the
Configuration Space Header.
cfg_dstatus[15:0]
Output
Configuration Device Status: Device status register from the
PCI Express Capability Structure.
cfg_dcommand[15:0]
Output
Configuration Device Command: Device control register from
the PCI Express Capability Structure.
cfg_dcommand2[15:0]
Output
Configuration Device Command 2: Device control 2 register
from the PCI Express Capability Structure.
cfg_lstatus[15:0]
Output
Configuration Link Status: Link status register from the PCI
Express Capability Structure.
cfg_lcommand[15:0]
Output
Configuration Link Command: Link control register from the
PCI Express Capability Structure.
cfg_aer_ecrc_gen_en
Output
Configuration AER - ECRC Generation Enable: AER Capability
and Control Register bit 6. When asserted, indicates that ECRC
Generation has been enabled by the host.
cfg_aer_ecrc_check_en
Output
Configuration AER - ECRC Check Enable: AER Capability and
Control Register bit 8. When asserted, indicates that ECRC
Checking has been enabled by the host.
cfg_pcie_link_state[2:0]
Output
PCI Express Link State: This encoded bus reports the PCI
Express Link State information.
• 000: L0
• 001: PPM L1
• 010: PPM L2/L3 Ready
• 011: PM_PME
• 100: in or transitioning to/from ASPM L0s
• 101: transitioning to/from PPM L1
• 110: transition to PPM L2/L3 Ready
• 111: Reserved
cfg_trn_pending
Input
User Transaction Pending: If asserted, sets the Transactions
Pending bit in the Device Status Register.
Note: You must assert this input if the user application has not
received a completion to an upstream request.
cfg_dsn[63:0]
Input
Configuration Device Serial Number: Serial Number Register
fields of the Device Serial Number extended capability.
cfg_pmcsr_pme_en
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Output
PMCSR PME Enable: PME_En bit (bit 8) in the Power
Management Control/Status Register.
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Chapter 2: Product Specification
Table 2-14:
Configuration Interface Signals (Cont’d)
Name
Direction
Description
cfg_pmcsr_pme_status
Output
PMCSR PME_Status: PME_Status bit (bit 15) in the Power
Management Control/Status Register.
cfg_pmcsr_powerstate[1:0]
Output
PMCSR PowerState: PowerState bits (bits 1:0) in the Power
Management Control/Status Register.
cfg_pm_halt_aspm_l0s
Input
Halt ASPM L0s: When asserted, it prevents the core from going
into ASPM L0s. If the core is already in L0s, it causes the core
to return to L0. cfg_pm_force_state, however, takes
precedence over this input.
cfg_pm_halt_aspm_l1
Input
Halt ASPM L1: When asserted, it prevents the core from going
into ASPM L1 (1). If the core is already in L1, it causes the core
to return to L0. cfg_pm_force_state, however, takes
precedence over this input.
cfg_pm_force_state[1:0]
Input
Force PM State: Forces the Power Management State machine
to attempt to stay in or move to the desired state.
• 00: Move to or stay in L0
• 01: Move to or stay in PPM L1
• 10: Move to or stay in ASPM L0s
• 11: Move to or stay in ASPM L1 (1)
cfg_pm_force_state_en
Input
Force PM State Transition Enable: Enables the transition to/
stay in the desired Power Management state, as indicated by
cfg_pm_force_state. If attempting to move to a desired
state, cfg_pm_force_state_en must be held asserted until
cfg_pcie_link_state indicates a move to the desired
state.
Output
Received Function Level Reset: Indicates when the Function
Level Reset has been received (FLR Configuration Register has
been set).
cfg_received_func_lvl_rst
Note: This feature is not supported in this core.
DEV_CAP_FUNCTION_LEVEL_RESET_CAPABLE is always set
to FALSE, and this port is unused.
cfg_vc_tcvc_map[6:0]
Output
Configuration VC Resource Control TC/VC Map: Indicates
whether TCs 1 through 7 are valid for VC0.
cfg_msg_received
Output
Message Received: Active-High. Notifies you that a Message
TLP was received on the Link.
cfg_msg_data[15:0]
Output
Message Requester ID: The Requester ID of the Message was
received. Valid only along with assertion of
cfg_msg_received.
Notes:
1. ASPM L1 is not supported in the 7 Series Integrated Block for PCIe.
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Chapter 2: Product Specification
Table 2-15:
Role-Specific Configuration Interface Signals: Endpoint
Name
Direction
Description
cfg_bus_number[7:0]
Output
Configuration Bus Number: Provides the assigned bus
number for the device. The user application must use
this information in the Bus Number field of outgoing
TLP requests. Default value after reset is 00h.
Refreshed whenever a Type 0 Configuration Write
packet is received.
cfg_device_number[4:0]
Output
Configuration Device Number: Provides the assigned
device number for the device. The user application
must use this information in the Device Number field
of outgoing TLP requests. Default value after reset is
00000b. Refreshed whenever a Type 0 Configuration
Write packet is received.
cfg_function_number[2:0]
Output
Configuration Function Number: Provides the
function number for the device. The user application
must use this information in the Function Number
field of outgoing TLP request. Function number is
hardwired to 000b.
cfg_to_turnoff
Output
Configuration To Turnoff: Output that notifies you that
a PME_TURN_Off message has been received and the
CMM starts polling the cfg_turnoff_ok input
coming in. After cfg_turnoff_ok is asserted, CMM
sends a PME_To_Ack message to the upstream device.
cfg_turnoff_ok
Input
Configuration Turnoff OK: The user application can
assert this to notify the Endpoint that it is safe to turn
off power.
cfg_pm_wake
Input
Configuration Power Management Wake: A one-clock
cycle assertion informs the core to generate and send
a Power Management Wake Event (PM_PME) Message
TLP to the upstream link partner.
Note: The user application asserts this input only
under stable link conditions as reported on the
cfg_pcie_link_state[2:0] bus. Assertion of this
signal when the PCI Express link is in transition results
in incorrect behavior on the PCI Express link.
cfg_msg_received_pm_as_nak
Output
Received Power Management Active State NAK
Message: Indicates that a PM_AS_NAK Message was
received on the link.
cfg_msg_received_setslotpowerlimit
Output
Received Set Slot Power Limit: Indicates that a Set Slot
Power Limit Message was received on the link. The
data of the Set Slot Power Limit Message is delivered
on the cfg_msg_data output.
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Chapter 2: Product Specification
Table 2-16:
Role-Specific Configuration Interface Signals: Root Port
Name
Direction
Description
cfg_ds_bus_number[7:0]
Input
Configuration Downstream Bus Number: Provides the
bus number (Requester ID) of the Downstream Port. This
is used in TLPs generated inside the core and does not
affect the TLPs presented on the AXI4-Stream interface.
cfg_ds_device_number[4:0]
Input
Configuration Downstream Device Number: Provides
the device number (Requester ID) of the Downstream
Port. This is used in TLPs generated inside the core and
does not affect the TLPs presented on the transaction
interface.
cfg_ds_function_number[2:0]
Input
Configuration Downstream Function Number: Provides
the function number (Requester ID) of the Downstream
Port. This is used in TLPs generated inside the core and
does not affect the TLPs presented on the transaction
interface.
cfg_wr_rw1c_as_rw
Input
Configuration Write RW1C Bit as RW: Indicates that the
current write operation should treat any RW1C bit as a
RW bit. Normally, a RW1C bit is cleared by writing a 1 to
it, and can normally only be set by internal core
conditions. However, during a configuration register
access operation with this signal asserted, for every bit
on cfg_di that is 1, the corresponding RW1C
configuration register bit is set to 1. A value of 0 on
cfg_di during this operation has no effect, and
non-RW1C bits are unaffected regardless of the value on
cfg_di.
cfg_msg_received_err_cor
Output
Received ERR_COR Message: Active-High. Indicates that
the core received an ERR_COR Message. Valid only along
with assertion of cfg_msg_received. The Requester
ID of this Message Transaction is provided on
cfg_msg_data[15:0].
cfg_msg_received_err_non_fatal
Output
Received ERR_NONFATAL Message: Active-High.
Indicates that the core received an ERR_NONFATAL
Message. Valid only along with assertion of
cfg_msg_received. The Requester ID of this Message
Transaction is provided on cfg_msg_data[15:0].
cfg_msg_received_err_fatal
Output
Received ERR_FATAL Message: Active-High. Indicates
that the core received an ERR_FATAL Message. Valid only
along with assertion of cfg_msg_received. The
Requester ID of this Message Transaction is provided on
cfg_msg_data[15:0].
Input
Configuration Send Turn-off: Asserting this active-Low
input causes the Root Port to send Turn Off Message.
When the link partner responds with a Turn Off Ack, this
is reported on cfg_msg_received_pme_to_ack, and
the final transition to L3 Ready is reported on
cfg_pcie_link_state. Tie-off to 0 for Endpoint.
cfg_pm_send_pme_to
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Chapter 2: Product Specification
Table 2-16:
Role-Specific Configuration Interface Signals: Root Port (Cont’d)
Name
Direction
Description
cfg_msg_received_err_pme_to_ack
Output
Received PME_TO_Ack Message: Active-High. Indicates
that the core received an PME_TO_Ack Message. Valid
only along with assertion of cfg_msg_received. The
Requester ID of this Message Transaction is provided on
cfg_msg_data[15:0].
cfg_msg_received_assert_inta
Output
Received Assert_INTA Message: Active-High. Indicates
that the core received an Assert INTA Message. Valid
only along with assertion of cfg_msg_received. The
Requester ID of this Message Transaction is provided on
cfg_msg_data[15:0].
cfg_msg_received_assert_intb
Output
Received Assert_INTB Message: Active-High. Indicates
that the core received an Assert_INTB Message. Valid
only along with assertion of cfg_msg_received. The
Requester ID of this Message Transaction is provided on
cfg_msg_data[15:0].
cfg_msg_received_assert_intc
Output
Received Assert_INTC Message: Active-High. Indicates
that the core received an Assert_INTC Message. Valid
only along with assertion of cfg_msg_received. The
Requester ID of this Message Transaction is provided on
cfg_msg_data[15:0].
cfg_msg_received_assert_intd
Output
Received Assert_INTD Message: Active-High. Indicates
that the core received an Assert_INTD Message. Valid
only along with assertion of cfg_msg_received. The
Requester ID of this Message Transaction is provided on
cfg_msg_data[15:0].
cfg_msg_received_deassert_inta
Output
Received Deassert_INTA Message: Active-High. Indicates
that the core received a Deassert_INTA Message. Valid
only along with assertion of cfg_msg_received. The
Requester ID of this Message Transaction is provided on
cfg_msg_data[15:0].
cfg_msg_received_deassert_intb
Output
Received Deassert_INTB Message: Active-High. Indicates
that the core received a Deassert_INTB Message. Valid
only along with assertion of cfg_msg_received. The
Requester ID of this Message Transaction is provided on
cfg_msg_data[15:0].
cfg_msg_received_deassert_intc
Output
Received Deassert_INTC Message: Active-High. Indicates
that the core received a Deassert_INTC Message. Valid
only along with assertion of cfg_msg_received. The
Requester ID of this Message Transaction is provided on
cfg_msg_data[15:0].
cfg_msg_received_deassert_intd
Output
Received Deassert_INTD Message: Active-High.
Indicates that the core received a Deassert_INTD
Message. Valid only along with assertion of
cfg_msg_received. The Requester ID of this Message
Transaction is provided on cfg_msg_data[15:0].
cfg_msg_received_pm_pme
Output
Received PME Message: Indicates that a Power
Management Event Message was received on the link.
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Interrupt Interface Signals
Table 2-17 defines the Interrupt interface signals.
Table 2-17:
Configuration Interface Signals: Interrupt Interface - Endpoint Only
Name
cfg_interrupt
Direction
Description
Input
Configuration Interrupt: Interrupt-request signal. The
user application can assert this input to cause the
selected interrupt message type to be transmitted by
the core. The signal should be held High until
cfg_interrupt_rdy is asserted.
Output
Configuration Interrupt Ready: Interrupt grant signal.
The simultaneous assertion of cfg_interrupt_rdy
and cfg_interrupt indicates that the core has
successfully transmitted the requested interrupt
message.
cfg_interrupt_assert
Input
Configuration Legacy Interrupt Assert/Deassert Select:
Selects between Assert and Deassert messages for
Legacy interrupts when cfg_interrupt is asserted.
Not used for MSI interrupts.
Value Message Type
1
Assert
0
Deassert
cfg_interrupt_di[7:0]
Input
Configuration Interrupt Data In: For MSIs, the portion of
the Message Data that the Endpoint must drive to
indicate the MSI vector number, if Multi-Vector
Interrupts are enabled. The value indicated by
cfg_interrupt_mmenable[2:0] determines the
number of lower-order bits of Message Data that the
Endpoint provides; the remaining upper bits of
cfg_interrupt_di[7:0] are not used. For
Single-Vector Interrupts, cfg_interrupt_di[7:0] is
not used. For Legacy Interrupt messages (Assert_INTx,
Deassert_INTx), only INTA (00h) is supported.
cfg_interrupt_do[7:0]
Output
cfg_interrupt_rdy
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lowest eight bits of the Message Data field in the MSI
capability structure of the Endpoint. This value is
provided for informational purposes and backwards
compatibility.
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Chapter 2: Product Specification
Table 2-17:
Configuration Interface Signals: Interrupt Interface - Endpoint Only (Cont’d)
Name
Direction
Description
cfg_interrupt_mmenable[2:0]
Output
Configuration Interrupt Multiple Message Enable: This is
the value of the Multiple Message Enable field and
defines the number of vectors the system allows for
multi-vector MSI. Values range from 000b to 101b. A
value of 000b indicates that single-vector MSI is
enabled, while other values indicate the number of
lower-order bits that can be overridden by
cfg_interrupt_di[7:0].
• 000: 0 bits
• 001: 1 bit
• 010: 2 bits
• 011: 3 bits
• 100: 4 bits
• 101: 5 bits
cfg_interrupt_msienable
Output
Configuration Interrupt MSI Enabled: Indicates that MSI
messaging is enabled.
• 0: Only Legacy (INTX) interrupts or MSI-X Interrupts
can be sent.
• 1: Only MSI Interrupts should be sent.
cfg_interrupt_msixenable
Output
Configuration Interrupt MSI-X Enabled: Indicates that
the MSI-X messaging is enabled.
• 0: Only Legacy (INTX) interrupts or MSI Interrupts can
be sent.
• 1: Only MSI-X Interrupts should be sent.
cfg_interrupt_msixfm
Output
Configuration Interrupt MSI-X Function Mask: Indicates
the state of the Function Mask bit in the MSI-X Message
Control field. If 0, the Mask bit of each vector determines
its masking. If 1, all vectors are masked, regardless of
their per-vector Mask bit states.
cfg_pciecap_interrupt_msgnum[4:0]
Input
Configuration PCIe Capabilities - Interrupt Message
Number: This input sets the Interrupt Message Number
field in the PCI Express Capability register. This input
value must be adjusted if only MSI is enabled and the
host adjusts the Multiple Message Enable field such that
it invalidates the current value.
cfg_interrupt_stat
Input
Configuration Interrupt Status: Causes the Interrupt
Status bit to be set or cleared when the automatic
setting of the Interrupt Status bit based on the Interrupt
Interface inputs is disabled.
Error Reporting Signals
Table 2-18 defines the user application error-reporting signals.
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Chapter 2: Product Specification
Table 2-18:
User Application Error-Reporting Signals
Port Name
Direction
Description
cfg_err_ecrc
Input
ECRC Error Report: You can assert this signal to report
an ECRC error (end-to-end CRC).
cfg_err_ur
Input
Configuration Error Unsupported Request: You can
assert this signal to report that an unsupported
request was received. This signal is ignored if
cfg_err_cpl_rdy is deasserted.
cfg_err_cpl_timeout(1)
Input
Configuration Error Completion Timeout: You can
assert this signal to report that a completion timed out.
cfg_err_cpl_unexpect
Input
Configuration Error Completion Unexpected: You can
assert this signal to report that an unexpected
completion was received.
cfg_err_cpl_abort
Input
Configuration Error Completion Aborted: You can
assert this signal to report that a completion was
aborted. This signal is ignored if cfg_err_cpl_rdy is
deasserted.
cfg_err_posted
Input
Configuration Error Posted: This signal is used to
further qualify any of the cfg_err_* input signals.
When this input is asserted concurrently with one of
the other signals, it indicates that the transaction that
caused the error was a posted transaction.
cfg_err_cor (1)
Input
Configuration Error Correctable Error: You can assert
this signal to report that a correctable error was
detected.
cfg_err_atomic_egress_blocked
Input
Configuration Error AtomicOp Egress Blocked: You can
assert this signal to report that an Atomic TLP was
blocked.
cfg_err_internal_cor
Input
Configuration Error Corrected Internal: You can assert
this signal to report that an Internal error occurred and
was corrected. This input is only sampled if AER is
enabled.
cfg_err_internal_uncor
Input
Configuration Error Uncorrectable Internal: You can
assert this signal to report that an Uncorrectable
Internal error occurred. This input is only sampled if
AER is enabled.
cfg_err_malformed
Input
Configuration Error Malformed Error: You can assert
this signal to report a Malformed Error.
cfg_err_mc_blocked
Input
Configuration Error MultiCast Blocked: You can assert
this signal to report that a Multicast TLP was blocked.
cfg_err_poisoned
Input
Configuration Error Poisoned TLP: You can assert this
signal to report that a Poisoned TLP was received.
Normally, only used if attribute
DISABLE_RX_POISONED_RESP=TRUE.
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Chapter 2: Product Specification
Table 2-18:
User Application Error-Reporting Signals (Cont’d)
Port Name
Direction
Description
cfg_err_no_recovery
Input
Configuration Error Cannot Recover: Used to further
qualify the cfg_err_poisoned and
cfg_err_cpl_timeout input signals. When this
input is asserted concurrently with one of these signals,
it indicates that the transaction that caused these
errors cannot be recovered from. For a Completion
Timeout, you can elect not to attempt the Request
again. For a received Poisoned TLP, you cannot
continue operation. In either case, assertion causes the
corresponding error to not be regarded as ANFE.
cfg_err_tlp_cpl_header[47:0]
Input
Configuration Error TLP Completion Header: Accepts
the header information when an error is signaled. This
information is required so that the core can issue a
correct completion, if required.
This information should be extracted from the received
error TLP and presented in the given format:
[47:41]
Lower Address
[40:29]
Byte Count
[28:26]
TC
[25:24]
Attr
[23:8]
Requester ID
[7:0]
Tag
cfg_err_cpl_rdy
Output
Configuration Error Completion Ready: When asserted,
this signal indicates that the core can accept assertions
on cfg_err_ur and cfg_err_cpl_abort for
Non-Posted Transactions. Assertions on cfg_err_ur
and cfg_err_cpl_abort are ignored when
cfg_err_cpl_rdy is deasserted.
cfg_err_locked
Input
Configuration Error Locked: This signal is used to
further qualify any of the cfg_err_* input signals.
When this input is asserted concurrently with one of
the other signals, it indicates that the transaction that
caused the error was a locked transaction.
This signal is for use in Legacy mode. To signal an
unsupported request or an aborted completion for a
locked transaction, this signal can be used to return a
Completion Locked with UR or CA status.
Note: When not in Legacy mode, the core
automatically returns a Completion Locked, if
appropriate.
cfg_err_aer_headerlog[127:0]
Input
Configuration Error AER Header Log: AER Header log
for the signaled error.
Output
Configuration Error AER Header Log Set: When
asserted, indicates that Error AER Header Log is Set in
the case of a Single Header implementation/Full in the
case of a Multi-Header implementation and the header
for user-reported error is not needed.
cfg_err_aer_headerlog_set
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Table 2-18:
User Application Error-Reporting Signals (Cont’d)
Port Name
Direction
Description
cfg_aer_interrupt_msgnum[4:0]
Input
Configuration AER Interrupt Message Number: This
input sets the AER Interrupt Message (Root Port only)
Number field in the AER Capability - Root Error Status
register.
If AER is enabled, this input must be driven to a value
appropriate for MSI or MSIx mode, whichever is
enabled. You must adjust this input value if only MSI is
enabled, and the host adjusts the Multiple Message
Enable field such that it invalidates the current value.
cfg_err_acs
Input
Configuration Error ACS Violation: You can assert this
signal to report that an ACS Violation has occurred.
Notes:
1. Assert these signals only if the device power state is D0. Asserting these signals in non-D0 device power states
might result in an incorrect operation on the PCIe link. For additional information, see the PCI Express Base
Specification, rev. 2.1, Section 5.3.1.2 [Ref 2].
Table 2-19 defines the Error and Advanced Error Reporting Status of the 7 Series Integrated
Block for PCIe when configured as a Root Port.
Table 2-19:
Error-Reporting Interface - Root Port Only
Name
Direction
Description
cfg_bridge_serr_en
Output
Configuration Bridge Control – SERR Enable:
When asserted, this enables the forwarding
of Correctable, Non-Fatal, and Fatal errors, as
set in the Bridge Control register bit 1. You
must enforce the forwarding of these errors.
cfg_slot_control_electromech_il_ctl_pulse
Output
Electromechanical Interlock Control:
Indicates that the Electromechanical
Interlock Control bit of the Slot Control
Configuration register was written with a ‘1’.
cfg_root_control_syserr_corr_err_en
Output
System Error on Correctable Error Enable:
Indicates the status of the System Error on
Correctable Error Enable bit in the Root
Control Configuration register. This enables
the user logic to generate a System Error for
reported Correctable Errors.
cfg_root_control_syserr_non_fatal_err_en
Output
System Error on Non-Fatal Error Enable:
Indicates the status of the System Error on
Non-Fatal Error Enable bit in the Root
Control Configuration register. This enables
the user logic to generate a System Error for
reported Non-Fatal Errors.
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Chapter 2: Product Specification
Table 2-19:
Error-Reporting Interface - Root Port Only (Cont’d)
Name
Direction
Description
cfg_root_control_syserr_fatal_err_en
Output
System Error on Fatal Error Enable: Indicates
the status of the System Error on Fatal Error
Enable bit in the Root Control Configuration
register. This enables the user logic to
generate a System Error for reported Fatal
Errors.
cfg_root_control_pme_int_en
Output
PME Interrupt Enable: Indicates the status of
the PME Interrupt Enable bit in the Root
Control Configuration register. This enables
the user logic to generate an Interrupt for
received PME messages.
cfg_aer_rooterr_corr_err_reporting_en
Output
AER Correctable Error Reporting Enable:
Indicates status of the AER Correctable Error
Reporting Enable bit in the AER Root Error
Command configuration register. This bit
enables the user logic to generate Interrupts
for reported Correctable Errors.
cfg_aer_rooterr_non_fatal_err_reporting_en
Output
AER Non-Fatal Error Reporting Enable:
Indicates status of the AER Non-Fatal Error
Reporting Enable bit in the AER Root Error
Command configuration register. This bit
enables the user logic to generate Interrupts
for reported Non-Fatal Errors.
cfg_aer_rooterr_fatal_err_reporting_en
Output
AER Fatal Error Reporting Enable: Indicates
status of the AER Fatal Error Reporting Enable
bit in the AER Root Error Command
configuration register. This bit enables the
user logic to generate Interrupts for reported
Fatal Errors.
cfg_aer_rooterr_corr_err_received
Output
AER Correctable Error Message Received:
Indicates status of the AER Correctable Error
Message Received bit in the AER Root Error
Status configuration register. This bit
indicates that a Correctable Error message
was received.
cfg_aer_rooterr_non_fatal_err_received
Output
AER Non-Fatal Error Message Received:
Indicates status of the AER Non-Fatal Error
Message Received bit in the AER Root Error
Status configuration register. This bit
indicates that a Non-Fatal Error message was
received.
cfg_aer_rooterr_fatal_err_received
Output
AER Fatal Error Message Received: Indicates
status of the AER Fatal Error Message
Received bit in the AER Root Error Status
configuration register. This bit indicates that
a Fatal Error message was received.
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Chapter 2: Product Specification
Dynamic Reconfiguration Port Interface
The Dynamic Reconfiguration Port (DRP) interface allows for the dynamic change of FPGA
configuration memory bits of the 7 Series FPGAs Integrated Block for PCI Express core.
These configuration bits are represented as attributes for the PCIE_2_1 library primitive,
which is instantiated as part of this core. Table 2-20 defines the DRP interface signals. For
detailed usage information, see Using the Dynamic Reconfiguration Port Interface,
page 142.
Table 2-20:
Dynamic Reconfiguration Port Interface Signals
Name
Direction
Description
pcie_drp_clk
Input
PCI Express DRP Clock: The rising edge of this signal is the
timing reference for all the other DRP signals. Normally,
drp_clk is driven with a global clock buffer. The maximum
frequency is defined in the appropriate 7 Series FPGAs data
sheet (see References in Appendix E).
pcie_drp_en
Input
PCI Express DRP Data Enable: When asserted, this signal
enables a read or write operation. If drp_dwe is deasserted,
it is a read operation, otherwise a write operation. For any
given drp_clk cycle, all other input signals are not affected
if drp_den is not active.
pcie_drp_we
Input
PCI Express DRP Write Enable: When asserted, this signal
enables a write operation to the port (see drp_den).
pcie_drp_addr[8:0]
Input
PCI Express DRP Address Bus: The value on this bus
specifies the individual cell that is written or read. The
address is presented in the cycle that drp_den is active.
pcie_drp_di[15:0]
Input
PCI Express DRP Data Input: The value on this bus is the data
written to the addressed cell. The data is presented in the
cycle that drp_den and drp_dwe are active, and is
captured in a register at the end of that cycle, but the actual
write occurs at an unspecified time before drp_drdy is
returned.
pcie_drp_rdy
Output
PCI Express DRP Ready: This signal is a response to
drp_den to indicate that the DRP cycle is complete and
another DRP cycle can be initiated. In the case of a DRP
read, the drp_do bus must be captured on the rising edge
of drp_clk in the cycle that drp_drdy is active. The
earliest that drp_den can go active to start the next port
cycle is the same clock cycle that drp_drdy is active.
pcie_drp_do[15:0]
Output
PCI Express DRP Data Out: If drp_dwe was inactive when
drp_den is activated, the value on this bus when
drp_drdy goes active is the data read from the addressed
cell. At all other times, the value on drp_do[15:0] is
undefined.
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Chapter 2: Product Specification
PCI Configuration Space
The PCI configuration space consists of three primary parts, illustrated in Table 2-21. These
include:
•
•
•
Legacy PCI v3.0 Type 0/1 Configuration Space Header
°
Type 0 Configuration Space Header used by Endpoint applications (see Table 2-22)
°
Type 1 Configuration Space Header used by Root Port applications (see Table 2-23)
Legacy Extended Capability Items
°
PCIe Capability Item
°
Power Management Capability Item
°
Message Signaled Interrupt (MSI) Capability Item
°
MSI-X Capability Item (optional)
PCIe Extended Capabilities
°
Device Serial Number Extended Capability Structure (optional)
°
Virtual Channel Extended Capability Structure (optional)
°
Vendor Specific Extended Capability Structure (optional)
°
Advanced Error Reporting Extended Capability Structure (optional)
°
Resizable BAR Extended Capability Structure (optional)
The core implements up to four legacy extended capability items. The remaining legacy
extended capability space from address 0xA8 to 0xFF is reserved or user-definable
(Endpoint configuration only). Also, the locations for any optional capability structure that
is not implemented are reserved. If you do not use this space, the core returns 0x00000000
when this address range is read. If you implement registers within user-definable locations
in the range 0xA8 to 0xFF, this space must be implemented in the user application. You are
also responsible for returning 0x00000000 for any address within this range that is not
implemented in the user application.
For more information about enabling this feature, see Chapter 4, Customizing and
Generating the Core. For more information about designing with this feature, see Designing
with Configuration Space Registers and Configuration Interface, page 105.
IMPORTANT: The core optionally implements up to three PCI Express Extended Capabilities. The
remaining PCI Express Extended Capability Space is available for you to implement.
The starting address of the space available to you depends on which, if any, of the five
optional PCIe Extended Capabilities are implemented. If you implement registers in this
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Chapter 2: Product Specification
space, you can select the starting location of this space, and this space must be
implemented in the user application. For more information about enabling this feature, see
Extended Capabilities, page 225. For more information about designing with this feature,
see Designing with Configuration Space Registers and Configuration Interface in Chapter 3.
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Chapter 2: Product Specification
Table 2-21:
Common PCI Configuration Space Header
31
16
15
0
Device ID
Vendor ID
000h
Status
Command
004h
Class Code
BIST
Header
Lat Timer
Rev ID
008h
Cache Ln
00Ch
010h
014h
018h
01Ch
Header Type Specific
020h
(see Table 2-22 and Table 2-23)
024h
028h
02Ch
030h
CapPtr
034h
038h
PM Capability
Data
Customizable (1)
Intr Pin
Intr Line
03Ch
NxtCap
PM Cap
040h
BSE
PMCSR
MSI Control
044h
NxtCap
MSI Cap
Message Address (Lower)
04Ch
Message Address (Upper)
050h
Reserved
Message Data
054h
Mask Bits
058h
Pending Bits
05Ch
PE Capability
NxtCap
PE Cap
PCI Express Device Capabilities
Device Status
060h
064h
Device Control
PCI Express Link Capabilities
068h
06Ch
Link Status
Link Control
Root Port Only(2)
048h
Slot Capabilities
070h
074h
Slot Status
Slot Control
078h
Root Capabilities
Root Control
07Ch
Root Status
080h
PCI Express Device Capabilities 2
084h
Device Status 2
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Chapter 2: Product Specification
Table 2-21:
Common PCI Configuration Space Header (Cont’d)
31
16
15
0
PCI Express Link Capabilities 2
Link Status 2
08Ch
Link Control 2
090h
Unimplemented Configuration Space
(Returns 0x00000000)
Optional
MSlx Control
NxtCap
094h098h
MSlx Cap
09Ch
Table
0A0h
Table Offset
BIR
PBA Offset
PBA
BIR
Reserved Legacy Configuration Space
(Returns 0x00000000)
Optional(3)
Optional
(3)
Next Cap
Cap.
Ver.
100h
PCI Express Device Serial Number (1st)
104h
PCI Express Device Serial Number (2nd)
108h
Next Cap
Next Cap
0A8h0FFh
PCI Express Extended Capability - DSN
Cap.
Ver.
PCI Express Extended
Capability - VC
10Ch
Port VC Capability Register 1
110h
Port VC Capability Register 2
114h
Port VC Status
Optional(3)
0A4h
Port VC Control
118h
VC Resource Capability Register 0
11Ch
VC Resource Control Register 0
120h
VC Resource Status Register 0
124h
Cap.
PCI Express Extended Capability - VSEC
128h
Ver.
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Vendor Specific Header
12Ch
Vendor Specific - Loopback Command
130h
Vendor Specific - Loopback Status
134h
Vendor Specific - Error Count #1
138h
Vendor Specific - Error Count #2
13Ch
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Chapter 2: Product Specification
Table 2-21:
Common PCI Configuration Space Header (Cont’d)
31
16
15
Next Cap
Cap. Ver.
0
PCI Express Extended Cap. ID (AER)
Uncorrectable Error Status Register
144h
Uncorrectable Error Mask Register
148h
Uncorrectable Error Severity Register
14Ch
Correctable Error Status Register
150h
Correctable Error Mask Register
154h
Advanced Error Cap. & Control Register
158h
Header Log Register 1
15Ch
Header Log Register 2
160h
Header Log Register 3
164h
Header Log Register 4
168h
Root Error Command Register
16Ch
Root Error Status Register
170h
Error Source ID Register
174h
Optional(3)
Optional, Root Port
only (3)
Next Cap
Cap. Ver.
PCI Express Extended Cap. ID (RBAR)
Resizable BAR Capability Register(0)
Reserved
Resizable BAR Control(0)
Reserved
Resizable BAR Capability Register(2)
Resizable BAR Capability Register(3)
Resizable BAR Capability Register(4)
198h
19Ch
Resizable BAR Control(4)
Resizable BAR Capability Register(5)
Reserved
190h
194h
Resizable BAR Control(3)
Reserved
188h
18Ch
Resizable BAR Control(2)
Reserved
180h
184h
Resizable BAR Control(1)
Reserved
178h
17Ch
Resizable BAR Capability Register(1)
Optional(3)
140h
1A0h
1A4h
Resizable BAR Control(5)
Reserved Extended Configuration Space (Returns Completion with 0x00000000 )
1A8h
1AChFFFh
Notes:
1. The MSI Capability Structure varies depending on the selections in the Vivado Integrated Design Environment
(IDE).
2. Reserved for Endpoint configurations (returns 0x00000000).
3. The layout of the PCI Express Extended Configuration Space (100h-FFFh) can change depending on which
optional capabilities are enabled. This table represents the Extended Configuration space layout when all five
optional extended capability structures are enabled. For more information, see Optional PCI Express Extended
Capabilities, page 113.
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Chapter 2: Product Specification
Table 2-22:
Type 0 PCI Configuration Space Header
31
16
15
0
Device ID
Vendor ID
00h
Status
Command
04h
Class Code
BIST
Header
Lat Timer
Rev ID
08h
Cache Ln
0Ch
Base Address Register 0
10h
Base Address Register 1
14h
Base Address Register 2
18h
Base Address Register 3
1Ch
Base Address Register 4
20h
Base Address Register 5
24h
Cardbus CIS Pointer
28h
Subsystem ID
Subsystem Vendor ID
Expansion ROM Base Address
Reserved
30h
CapPtr
Reserved
Max Lat
Min Gnt
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34h
38h
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3Ch
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Chapter 2: Product Specification
Table 2-23:
Type 1 PCI Configuration Space Header
31
16
15
0
Device ID
Vendor ID
00h
Status
Command
04h
Class Code
BIST
Header
Second Lat Timer
Lat Timer
Rev ID
08h
Cache Ln
0Ch
Base Address Register 0
10h
Base Address Register 1
14h
Sub Bus Number
Secondary Status
Second Bus Number
Primary Bus Number
18h
I/O Limit
I/O Base
1Ch
Memory Limit
Memory Base
20h
Prefetchable Memory Limit
Prefetchable Memory Base
24h
Prefetchable Base Upper 32 Bits
28h
Prefetchable Limit Upper 32 Bits
2Ch
I/O Limit Upper 16 Bits
I/O Base Upper 16 Bits
Reserved
CapPtr
Expansion ROM Base Address
Bridge Control
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34h
38h
Intr Line
3Ch
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Chapter 3
Designing with the Core
This chapter includes guidelines and additional information to make designing with the
core easier. It provides design instructions for the 7 Series FPGAs Integrated Block for
PCI Express® user interface and assumes knowledge of the PCI Express transaction layer
packet (TLP) header fields. Header fields are defined in the “Transaction Layer
Specification” chapter of the PCI Express Base Specification v2.1 [Ref 2].
General Design Guidelines
Designing with the 64-Bit Transaction Layer Interface
TLP Format on the AXI4-Stream Interface
Data is transmitted and received in Big-Endian order as required by the PCI Express Base
Specification [Ref 2]. See the “Transaction Layer Specification” chapter of the PCI Express
Base Specification for detailed information about TLP packet ordering. Figure 3-1 represents
a typical 32-bit addressable Memory Write Request TLP (as illustrated in the “Transaction
Layer Specification” chapter of the specification).
.
X-Ref Target - Figure 3-1
+0
+1
+2
+3
7 6 5 4 3 2 1 0 7 6 5 4 3 2 1 0 7 6 5 4 3 2 1 0 7 6 5 4 3 2 1 0
Byte 0 >
R
Fmt
x0
Type
R
TC
R Attr R
T T E
Attr
HD P
Requester ID
Byte 4 >
AT
Tag
Length
Last DW 1st DW
BE
BE
Address[31:2]
Byte 8 >
Byte 12 >
Data 0
Byte 16 >
Data 1
Byte 20 >
Data 2
Byte 24 >
TLP Digest
Figure 3-1:
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Chapter 3: Designing with the Core
When using the AXI4-Stream interface, packets are arranged on the entire 64-bit datapath.
Figure 3-2 shows the same example packet on the AXI4-Stream interface. Byte 0 of the
packet appears on s_axis_tx_tdata[31:24] (transmit) or
m_axis_rx_tdata[31:24] (receive) of the first QWORD, byte 1 on
s_axis_tx_tdata[23:16] or m_axis_rx_tdata[23:16]. Byte 8 of the packet then
appears on s_axis_tx_tdata[31:24] or m_axis_rx_tdata[31:24] of the second
QWORD. The Header section of the packet consists of either three or four DWORDs,
determined by the TLP format and type as described in section 2.2 of the PCI Express Base
Specification.
X-Ref Target - Figure 3-2
AXI Bit
63
AXI Byte
PCIe Byte
32 31
0
+7
+6
+5
+4
+3
+2
+1
+0
+4
+5
+6
+7
+0
+1
+2
+3
7 6 5 4 3 2 1 0 7 6 5 4 3 2 1 0 7 6 5 4 3 2 1 0 7 6 5 4 3 2 1 0 7 6 5 4 3 2 1 0 7 6 5 4 3 2 1 0 7 6 5 4 3 2 1 0 7 6 5 4 3 2 1 0
Clock 0
Requester ID
Clock 1
Tag
Last DW
BE
1st DW
BE
R
Fmt
x 0
Data[31:0]
Figure 3-2:
Type
R
TC
R
T E
Attr
D P
R
Length
Address [31:2]
R
Endpoint Integrated Block Byte Order
IMPORTANT: Packets sent to the core for transmission must follow the formatting rules for transaction
layer packets (TLPs) as specified in the “Transaction Layer Specification” chapter of the PCI Express Base
Specification.
Note: The user application is responsible for ensuring the validity of its packets. The core does not
check that a packet is correctly formed and this can result in transferring a malformed TLP. The exact
fields of a given TLP vary depending on the type of packet being transmitted.
Transmitting Outbound Packets
Basic TLP Transmit Operation
The 7 Series FPGAs Integrated Block for PCI Express core automatically transmits these
types of packets:
•
Completions to a remote device in response to Configuration Space requests.
•
Error-message responses to inbound requests that are malformed or unrecognized by
the core.
Note: Certain unrecognized requests, for example, unexpected completions, can only be
detected by the user application, which is responsible for generating the appropriate response.
The user application is responsible for constructing these types of outbound packets:
•
Memory, Atomic Ops, and I/O Requests to remote devices.
•
Completions in response to requests to the user application, for example, a Memory
Read Request.
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Chapter 3: Designing with the Core
•
Completions in response to user-implemented Configuration Space requests, when
enabled. These requests include PCI™ legacy capability registers beyond address BFh
and PCI Express extended capability registers beyond address 1FFh.
Note: For information about accessing user-implemented Configuration Space while in a
low-power state, see Power Management, page 134.
When configured as an Endpoint, the core notifies the user application of pending
internally generated TLPs that arbitrate for the transmit datapath by asserting tx_cfg_req
(1b). The user application can choose to give priority to core-generated TLPs by asserting
tx_cfg_gnt (1b) permanently, without regard to tx_cfg_req. Doing so prevents
User-Application-generated TLPs from being transmitted when a core-generated TLP is
pending. Alternatively, the user application can reserve priority for a generated TLP over
core-generated TLPs, by deasserting tx_cfg_gnt (0b) until the user transaction is
complete. When the user transaction is complete, the user application can assert
tx_cfg_gnt (1b) for at least one clock cycle to allow the pending core-generated TLP to
be transmitted. You must not delay asserting tx_cfg_gnt indefinitely, because this might
cause a completion timeout in the requester. See the PCI Express Base Specification [Ref 2]
for more information on the Completion Timeout Mechanism.
The integrated block does not do any filtering on the Base/Limit registers (Root Port only).
You are responsible for determining if filtering is required. These registers can be read out
of the Type 1 Configuration Header space through the Configuration interface (see
Designing with Configuration Space Registers and Configuration Interface, page 105).
Table 2-9, page 16 defines the transmit user application signals. To transmit a TLP, the user
application must perform this sequence of events on the transmit transaction interface:
1. The user application logic asserts s_axis_tx_tvalid and presents the first TLP
QWORD on s_axis_tx_tdata[63:0]. If the core is asserting s_axis_tx_tready,
the QWORD is accepted immediately; otherwise, the user application must keep the
QWORD presented until the core asserts s_axis_tx_tready.
2. The user application asserts s_axis_tx_tvalid and presents the remainder of the
TLP QWORDs on s_axis_tx_tdata[63:0] for subsequent clock cycles (for which the
core asserts s_axis_tx_tready).
3. The user application asserts s_axis_tx_tvalid and s_axis_tx_tlast together
with the last QWORD data. If all eight data bytes of the last transfer are valid, they are
presented on s_axis_tx_tdata[63:0] and s_axis_tx_tkeep is driven to 0xFF;
otherwise, the four remaining data bytes are presented on s_axis_tx_tdata[31:0],
and s_axis_tx_tkeep is driven to 0x0F.
4. At the next clock cycle, the user application deasserts s_axis_tx_tvalid to signal
the end of valid transfers on s_axis_tx_tdata[63:0].
Figure 3-3 illustrates a 3-DW TLP header without a data payload; an example is a 32-bit
addressable Memory Read request. When the user application asserts s_axis_tx_tlast,
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Chapter 3: Designing with the Core
it also places a value of 0x0F on s_axis_tx_tkeep, notifying the core that only
s_axis_tx_tdata[31:0] contains valid data.
X-Ref Target - Figure 3-3
user_clock_out
s_axis_tx_tdata[63:0]
H1H0
--H2
FFh
0Fh
s_axis_tx_tready
s_axis_tx_tvalid
s_axis_tx_tlast
s_axis_tx_tkeep[7:0]
(tx_err_fwd)s_axis_tx_tuser[1]
(tx_str)s_axis_tx_tuser[2]
(tx_src_dsc)s_axis_tx_tuser[3]
tx_terr_drop
Figure 3-3:
TLP 3-DW Header without Payload
Figure 3-4 illustrates a 4-DW TLP header without a data payload; an example is a 64-bit
addressable Memory Read request. When the user application asserts s_axis_tx_tlast,
it also places a value of 0xFF on s_axis_tx_tkeep, notifying the core that
s_axis_tx_tdata[63:0] contains valid data.
X-Ref Target - Figure 3-4
user_clk_out
s_axis_tx_tdata[63:0]
H1H0
H3H2
s_axis_tx_tready
s_axis_tx_tvalid
s_axis_tx_tlast
s_axis_tx_tkeep[7:0]
FFh
(tx_err_fwd)s_axis_tx_tuser[1]
(tx_str)s_axis_tx_tuser[2]
(tx_src_dsc)s_axis_tx_tuser[3]
tx_terr_drop
Figure 3-4:
TLP with 4-DW Header without Payload
Figure 3-5 illustrates a 3-DW TLP header with a data payload; an example is a 32-bit
addressable Memory Write request. When the user application asserts s_axis_tx_tlast,
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Chapter 3: Designing with the Core
it also puts a value of 0xFF on s_axis_tx_tkeep, notifying the core that
s_axis_tx_tdata[63:0] contains valid data.
X-Ref Target - Figure 3-5
user_clock_out
s_axis_tx_tdata[63:0]
H1H0
D0H2
D2D1
Dn-2Dn-3
DnDn-1
s_axis_tx_tready
s_axis_tx_tvalid
s_axis_tx_tlast
s_axis_tx_tkeep[7:0]
FFh
FFh
(terr_fwd)s_axis_tx_tuser[1]
(str)s_axis_tx_tuser[2]
(src_dsc)s_axis_tx_tuser[3]
tx_terr_drop
Figure 3-5:
TLP with 3-DW Header with Payload
Figure 3-6 illustrates a 4-DW TLP header with a data payload; an example is a 64-bit
addressable Memory Write request. When the user application asserts s_axis_tx_tlast,
it also places a value of 0x0F on s_axis_tx_tkeep, notifying the core that only
s_axis_tx_tdata[31:0] contains valid data.
X-Ref Target - Figure 3-6
user_clk_out
s_axis_tx_tdata[63:0]
H1H0
H3H2
D1D0
D3D2
Dn-1Dn-2
--Dn
s_axis_tx_tready
s_axis_tx_tvalid
s_axis_tx_tlast
s_axis_tx_tkeep[7:0]
FFh
0Fh
(terr_fwd)s_axis_tx_tuser[1]
(str)s_axis_tx_tuser[2]
(src_dsc)s_axis_tx_tuser[3]
tx_terr_drop
Figure 3-6:
TLP with 4-DW Header with Payload
Presenting Back-to-Back Transactions on the Transmit Interface
The user application can present back-to-back TLPs on the transmit AXI4-Stream interface
to maximize bandwidth utilization. Figure 3-7 illustrates back-to-back TLPs presented on
the transmit interface. The user application keeps s_axis_tx_tvalid asserted and
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Chapter 3: Designing with the Core
presents a new TLP on the next clock cycle after asserting s_axis_tx_tlast for the
previous TLP.
X-Ref Target - Figure 3-7
user_clk_out
s_axis_tx_tdata[63:0]
H1H0
D0H2
D2D1
D4D3
TLP1
H1H0
D0H2
D2D1
TLP2
s_axis_tx_tready
s_axis_tx_tvalid
s_axis_tx_tlast
s_axis_tx_tkeep[7:0]
Figure 3-7:
FFh
FFh
Back-to-Back Transaction on the Transmit Interface
Source Throttling on the Transmit Datapath
The transaction interface lets the user application throttle back if it has no data to present
on s_axis_tx_tdata[63:0]. When this condition occurs, the user application deasserts
s_axis_tx_tvalid, which instructs the core AXI4-Stream interface to disregard data
presented on s_axis_tx_tdata[63:0]. Figure 3-8 illustrates the source throttling
mechanism, where the user application does not have data to present every clock cycle, and
for this reason must deassert s_axis_tx_tvalid during these cycles.
X-Ref Target - Figure 3-8
user_clk_out
s_axis_tx_tdata[63:0]
s_axis_tx_tready
s_axis_tx_tvalid
s_axis_tx_tlast
s_asix_tx_tkeep[7:0]
Figure 3-8:
FFh
Source Throttling on the Transmit Interface
Destination Throttling of the Transmit Datapath
The core AXI4-Stream interface throttles the transmit user application if there is no space
left for a new TLP in its transmit buffer pool. This can occur if the link partner is not
processing incoming packets at a rate equal to or greater than the rate at which the user
application is presenting TLPs. Figure 3-9 illustrates the deassertion of
s_axis_tx_tready to throttle the user application when the internal transmit buffers of
the core are full. If the core needs to throttle the user application, it does so after the
current packet has completed. If another packet starts immediately after the current packet,
the throttle occurs immediately after tlast.
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Chapter 3: Designing with the Core
X-Ref Target - Figure 3-9
user_clock_out
s_axis_tx_tdata
[63:0]
TLP1
TLP2
s_axis_tx_tready
s_axis_tx_tvalid
s_axis_tx_tlast
tx_buf_av[5:0]
0d
1d
New Buffer Available
Figure 3-9:
0d
1d
0d
New Buffer Available
Destination Throttling on the Transmit Interface
If the core transmit AXI4-Stream interface accepts the start of a TLP by asserting
s_axis_tx_tready, it is guaranteed to accept the complete TLP with a size up to the
value contained in the Max_Payload_Size field of the PCI Express Device Capability Register
(offset 04H). To stay compliant to the PCI Express Base Specification [Ref 2], you should not
violate the Max_Payload_Size field of the PCI Express Device Control Register (offset 08H).
The core transmit AXI4-Stream interface deasserts s_axis_tx_tready only under these
conditions:
•
The core does not have enough buffering if the packets are not drained due to lack of
credits made available from the link partner.
•
When the core is transmitting an internally generated TLP (Completion TLP because of
a Configuration Read or Write, error Message TLP or error response as requested by
the user application on the cfg_err interface), after it has been granted use of the
transmit datapath by the user application, by assertion of tx_cfg_gnt. The core
subsequently asserts s_axis_tx_tready after transmitting the internally generated
TLP.
•
When the Power State field in Power Management Control/Status Register (offset 0x4)
of the PCI Power Management Capability Structure is changed to a non-D0 state. When
this occurs, any ongoing TLP is accepted completely and s_axis_tx_tready is
subsequently deasserted, disallowing the user application from initiating any new
transactions for the duration that the core is in the non-D0 power state.
On deassertion of s_axis_tx_tready by the core, the user application needs to hold all
control and data signals until the core asserts s_axis_tx_tready.
Discontinuing Transmission of Transaction by Source
The core AXI4-Stream interface lets the user application terminate transmission of a TLP by
asserting s_axis_tx_tuser[3](tx_src_dsc). Both s_axis_tx_tvalid and
s_axis_tx_tready must be asserted together with tx_src_dsc for the TLP to be
discontinued. The signal tx_src_dsc must not be asserted at the beginning of a new
packet. It can be asserted on any cycle after the first beat of a new packet has been
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Chapter 3: Designing with the Core
accepted by the core up to and including the assertion of s_axis_tx_tlast. Asserting
src_dsc has no effect if no TLP transaction is in progress on the transmit interface.
Figure 3-10 illustrates the user application discontinuing a packet using tx_src_dsc.
Asserting src_dsc with s_axis_tx_tlast is optional.
If streaming mode is not used, s_axis_tx_tuser[2] = 0b(tx_str), and the packet is
discontinued, then the packet is discarded before being transmitted on the serial link. If
streaming mode is used (tx_str = 1b), the packet is terminated with the EDB symbol on
the serial link.
X-Ref Target - Figure 3-10
user_clock_out
s_axis_tx_tdata[63:0]
H1H0
D0H2
D2D1
D4D3
s_axis_tx_tready
s_axis_tx_tvalid
s_axis_tx_tlast
s_axis_tx_tkeep[7:0]
FFh
(tx_src_dsc) s_axis_tx_tuser[3]
Figure 3-10:
Source Driven Transaction Discontinue on the Transmit Interface
Discarding of Transaction by Destination
The core transmit AXI4-Stream interface discards a TLP for three reasons:
•
PCI Express Link goes down.
•
Presented TLP violates the Max_Payload_Size field of the PCI Express Device Capability
Register (offset 04H). It is your responsibility to not violate the Max_Payload_Size field
of the Device Control Register (offset 08H).
•
s_axis_tx_tuser[2](tx_str) is asserted and data is not presented on
consecutive clock cycles, that is, s_axis_tx_tvalid is deasserted in the middle of a
TLP transfer.
When any of these occur, the transmit AXI4-Stream interface continues to accept the
remainder of the presented TLP and asserts tx_err_drop no later than the second clock
cycle following the s_axis_tx_tlast of the discarded TLP. Figure 3-11 illustrates the
core signaling that a packet was discarded using tx_err_drop.
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X-Ref Target - Figure 3-11
user_clk_out
s_axis_tx_tdata[63:0]
H1H0
D0H2
--D1
Dropped TLP
H 1H 0
D0H2
--D1
Valid TLP
s_axis_tx_tready
s_axis_tx_tvalid
s_axis_tx_tlast
s_axis_tx_tkeep[7:0]
FFh
0Fh
FFh
0Fh
(tx_src_dsc)s_axis_tx_tuser[3]
tx_terr_drop
Figure 3-11:
Discarding of Transaction by Destination of Transmit Interface
Packet Data Poisoning on the Transmit AXI4-Stream Interface
The user application uses either of these mechanisms to mark the data payload of a
transmitted TLP as poisoned:
•
Set EP = 1 in the TLP header. This mechanism can be used if the payload is known to be
poisoned when the first DWORD of the header is presented to the core on the
AXI4-Stream interface.
•
Assert s_axis_tx_tuser[1](tx_err_fwd) for at least one valid data transfer cycle
any time during the packet transmission, as shown in Figure 3-12. This causes the core
to set EP = 1 in the TLP header when it transmits the packet onto the PCI Express fabric.
This mechanism can be used if the user application does not know whether a packet
could be poisoned at the start of packet transmission. Use of terr_fwd is not
supported for packets when s_axis_tx_tuser[2](tx_str) is asserted (streamed
transmit packets). In streaming mode, you can optionally discontinue the packet if it
becomes corrupted. See Discontinuing Transmission of Transaction by Source, page 52
for details on discontinuing packets.
When ECRC is being used, instead of setting the EP bit of the TLP to forward an error, the
user application should nullify TLPs with errors by asserting the
src_dsc(s_axis_tx_tuser[3]) block input for the TLP and report the error using the
cfg_err interface.
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Chapter 3: Designing with the Core
X-Ref Target - Figure 3-12
user_clk_out
s_axis_tx_tdata[63:0]
Poisoned TLP
s_axis_tx_tvalid
s_axis_tx_tlast
s_axis_tx_tkeep[7:0]
FFh
FFh
0Fh
(tx_err_fwd)s_axis_tx_tuser[1]
Figure 3-12:
Packet Data Poisoning on the Transmit Interface
Streaming Mode for Transactions on the Transmit Interface
The 7 Series FPGAs Integrated Block for PCI Express core allows the user application to
enable Streaming (cut-through) mode for transmission of a TLP, when possible, to reduce
latency of operation. To enable this feature, the user application must hold
s_axis_tx_tuser[2](tx_str) asserted for the entire duration of the transmitted TLP.
The user application must also present valid frames on every clock cycle until the final cycle
of the TLP. In other words, the user application must not deassert s_axis_tx_tvalid for
the duration of the presented TLP. Source throttling of the transaction while in streaming
mode of operation causes the transaction to be dropped (tx_err_drop is asserted) and a
nullified TLP to be signaled on the PCI Express link. Figure 3-13 illustrates the streaming
mode of operation, where the first TLP is streamed and the second TLP is dropped because
of source throttling.
X-Ref Target - Figure 3-13
user_clk_out
s_axis_tx_tdata[63:0]
TLP1
TLP2
s_axis_tx_tready
s_axis_tx_tvalid
s_axis_tx_tlast
s_axis_tx_tkeep[7:0]
FFh
FFh
FFh
(tx_str)s_axis_tx_tuser[2]
tx_terr_drop
Figure 3-13:
Streaming Mode on the Transmit Interface
Using ECRC Generation
The integrated block supports automatic ECRC generation. To enable this feature, the user
application must assert s_axis_tx_tuser[0](tx_ecrc_gen) at the beginning of a TLP
on the transmit AXI4-Stream interface. This signal can be asserted through the duration of
the packet, if desired. If the outgoing TLP does not already have a digest, the core generates
and appends one and sets the TD bit. There is a single-clock cycle deassertion of
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Chapter 3: Designing with the Core
s_axis_tx_tready at the end-of-packet to allow for insertion of the digest. Figure 3-14
illustrates ECRC generation operation.
X-Ref Target - Figure 3-14
user_clk_out
s_axis_tx_tdata[63:0]
H1H0
D0H2
D2D1
D4D3
H1H0
TLP1
D0H2
D2D1
TLP2
s_axis_tx_tready
s_axis_tx_tvalid
s_axis_tx_tlast
s_axis_tx_tkeep[7:0]
FFh
FFh
(tx_ecrc_gen) s_axis_tx_tuser[0]
Figure 3-14:
ECRC Generation
Receiving Inbound Packets
Basic TLP Receive Operation
Table 2-10, page 19 defines the receive AXI4-Stream interface signals. This sequence of
events must occur on the receive AXI4-Stream interface for the Endpoint core to present a
TLP to the user application logic:
1. When the user application is ready to receive data, it asserts m_axis_rx_tready.
2. When the core is ready to transfer data, the core asserts m_axis_rx_tvalid and
presents the first complete TLP QWORD on m_axis_rx_tdata[63:0].
3. The core keeps m_axis_rx_tvalid asserted, and presents TLP QWORDs on
m_axis_rx_tdata[63:0] on subsequent clock cycles (provided the user application
logic asserts m_axis_rx_tready).
4. The core then asserts m_axis_rx_tvalid with m_axis_rx_tlast and presents
either the last QWORD on s_axis_tx_tdata[63:0] and a value of 0xFF on
m_axis_rx_tkeep or the last DWORD on s_axis_tx_tdata[31:0] and a value of
0x0F on m_axis_rx_tkeep.
5. If no further TLPs are available at the next clock cycle, the core deasserts
m_axis_rx_tvalid to signal the end of valid transfers on
m_axis_rx_tdata[63:0].
Note: The user application should ignore any assertions of m_axis_rx_tlast,
m_axis_rx_tkeep, and m_axis_rx_tdata unless m_axis_rx_tvalid is concurrently asserted.
The m_axis_rx_tvalid signal is never deasserted mid-packet.
Figure 3-15 shows a 3-DW TLP header without a data payload; an example is a 32-bit
addressable Memory Read request. When the core asserts m_axis_rx_tlast, it also
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Chapter 3: Designing with the Core
places a value of 0x0F on m_axis_rx_tkeep, notifying you that only
m_axis_rx_tdata[31:0] contains valid data.
X-Ref Target - Figure 3-15
user_clk_out
m_axis_rx_tdata[63:0]
H1H0
--H3
FFh
0Fh
m_axis_rx_tready
m_axis_rx_tvalid
m_axis_rx_tlast
m_axis_rx_tkeep[7:0]
(rx_err_fwd) m_axis_rx_tuser[1]
(rx_bar_hit[7:0]) m_axis_rx_tuser[9:2]
Figure 3-15:
TLP 3-DW Header without Payload
Figure 3-16 shows a 4-DW TLP header without a data payload; an example is a 64-bit
addressable Memory Read request. When the core asserts m_axis_rx_tlast, it also
places a value of 0xFF on m_axis_rx_tkeep, notifying you that
m_axis_rx_tdata[63:0] contains valid data.
X-Ref Target - Figure 3-16
user_clk_out
m_axis_rx_tdata[63:0]
H1H0
H3H2
m_axis_rx_tready
m_axis_rx_tvalid
m_axis_rx_tlast
m_axis_rx_tkeep[7:0]
FFh
(rx_err_fwd) m_axis_rx_tuser[1]
(rx_bar_hit[7:0]) m_axis_rx_tuser[9:2]
Figure 3-16:
TLP 4-DW Header without Payload
Figure 3-17 shows a 3-DW TLP header with a data payload; an example is a 32-bit
addressable Memory Write request. When the core asserts m_axis_rx_tlast, it also
places a value of 0xFF on m_axis_rx_tkeep, notifying you that
m_axis_rx_tdata[63:0] contains valid data.
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Chapter 3: Designing with the Core
X-Ref Target - Figure 3-17
user_clock_out
m_axis_rx_tdata[63:0]
H1H0
D0H2
D2D1
D4D3
m_axis_rx_tready
m_axis_rx_tvalid
m_axis_rx_tlast
m_axis_rx_tkeep[7:0]
FFh
(rx_err_fwd)m_axis_rx_tuser[1]
(rx_bar_hit[7:0])m_axis_rx_tuser[9:2]
Figure 3-17:
00000010b
TLP 3-DW Header with Payload
Figure 3-18 shows a 4-DW TLP header with a data payload; an example is a 64-bit
addressable Memory Write request. When the core asserts m_axis_rx_tlast, it also
places a value of 0x0F on m_axis_rx_tkeep, notifying you that only
m_axis_rx_tdata[31:0] contains valid data.
X-Ref Target - Figure 3-18
user_clk_out
m_axis_rx_tdata[63:0]
H1H0
H3H2
D1D0
--D2
m_axis_rx_tready
m_axis_rx_tvalid
m_axis_rx_tlast
m_axis_rx_tkeep[7:0]
FFh
0Fh
(rx_err_fwd)m_axis_rx_tuser[1]
(rx_bar_hit[7:0])m_axis_rx_tuser[9:2]
00110000b
rx_np_ok
Figure 3-18:
TLP 4-DW Header with Payload
Throttling the Datapath on the Receive AXI4-Stream Interface
The user application can stall the transfer of data from the core at any time by deasserting
m_axis_rx_tready. If you deassert m_axis_rx_tready while no transfer is in progress
and if a TLP becomes available, the core asserts m_axis_rx_tvalid and presents the first
TLP QWORD on m_axis_rx_tdata[63:0]. The core remains in this state until you assert
m_axis_rx_tready to signal the acceptance of the data presented on
m_axis_rx_tdata[63:0]. At that point, the core presents subsequent TLP QWORDs as
long as m_axis_rx_tready remains asserted. If you deassert m_axis_rx_tready
during the middle of a transfer, the core stalls the transfer of data until you assert
m_axis_rx_tready again. There is no limit to the number of cycles you can keep
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Chapter 3: Designing with the Core
m_axis_rx_tready deasserted. The core pauses until the user application is again ready
to receive TLPs.
Figure 3-19 illustrates the core asserting m_axis_rx_tvalid along with presenting data
on m_axis_rx_tdata[63:0]. The user application logic inserts wait states by
deasserting m_axis_rx_tready. The core does not present the next TLP QWORD until it
detects m_axis_rx_tready assertion. The user application logic can assert or deassert
m_axis_rx_tready as required to balance receipt of new TLP transfers with the rate of
TLP data processing inside the application logic.
X-Ref Target - Figure 3-19
user_clk_out
m_axis_rx_tdata[63:0]
m_axis_rx_tready
m_axis_rx_tvalid
m_axis_rx_tlast
Figure 3-19:
User Application Throttling Receive TLP
Receiving Back-to-Back Transactions on the Receive Interface
The user application logic must be designed to handle presentation of back-to-back TLPs
on the receive AXI4-Stream interface by the core. The core can assert m_axis_rx_tvalid
for a new TLP at the clock cycle after m_axis_rx_tlast assertion for the previous TLP.
Figure 3-20 illustrates back-to-back TLPs presented on the receive interface.
X-Ref Target - Figure 3-20
user_clk_out
m_axis_rx_tdata[63:0]
TLP1
TLP2
m_axis_rx_tready
m_axis_rx_tvalid
m_axis_rx_tlast
Figure 3-20:
Receive Back-to-Back Transactions
If the user application cannot accept back-to-back packets, it can stall the transfer of the
TLP by deasserting m_axis_rx_tready as discussed in the Throttling the Datapath on the
Receive AXI4-Stream Interface section. Figure 3-21 shows an example of using
m_axis_rx_tready to pause the acceptance of the second TLP.
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Chapter 3: Designing with the Core
X-Ref Target - Figure 3-21
user_clk_out
m_axis_rx_tdata[63:0]
TLP1
TLP2
m_axis_rx_tready
m_axis_rx_tvalid
m_axis_rx_tlast
m_axis_rx_tkeep[7:0]
Figure 3-21:
FFh
0Fh
User Application Throttling Back-to-Back TLPs
Packet Re-ordering on Receive Interface
Transaction processing in the core receiver is fully compliant with the PCI transaction
ordering rules, described in Chapter 2 of the PCI Express Base Specification [Ref 2]. The
transaction ordering rules allow Posted and Completion TLPs to bypass blocked
Non-Posted TLPs.
The core provides two mechanisms for user applications to manage their Receiver
Non-Posted Buffer space.
1. Receive Non-Posted Throttling: The use of rx_np_ok to prevent the core from
presenting more than two Non-Posted requests after deassertion of the rx_np_ok
signal. The second mechanism,
2. Receive Request for Non-Posted: Allows user-controlled Flow Control of the
Non-Posted queue, using the rx_np_req signal.
The Receive Non-Posted Throttling mechanism assumes that the user application normally
has space in its receiver for non-Posted TLPs and the user application would throttle the
core specifically for Non-Posted requests. The Receive Request for Non-Posted mechanism
assumes that the user application requests the core to present a Non-Posted TLP when it
has space in its receiver. The two mechanisms are mutually exclusive, and only one can be
active for a design. This option must be selected while generating and customizing the
core. When the Receive Non-Posted Request option is selected in the Advanced Settings,
the Receive Request for Non-Posted mechanism is enabled and any assertion/deassertion
of rx_np_ok is ignored and vice-versa. The two mechanisms are described in further detail
in the next subsections.
•
Receive Non-Posted Throttling (Receive Non-Posted Request Disabled,
TRN_ NP_ FC attribute FALSE)
If the user application can receive Posted and Completion Transactions from the core,
but is not ready to accept Non-Posted Transactions, the user application can deassert
rx_np_ok, as shown in Figure 3-22. The user application must deassert rx_np_ok at
least two clock cycles before m_axis_rx_tlast of the second-to-last Non-Posted TLP
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Chapter 3: Designing with the Core
that the user application can accept. While rx_np_ok is deasserted, received Posted
and Completion Transactions pass Non-Posted Transactions. After the user application
is ready to accept Non-Posted Transactions, it must reassert rx_np_ok. Previously
bypassed Non-Posted Transactions are presented to the user application before other
received TLPs. There is no limit as to how long rx_np_ok can be deasserted; however,
you must take care to not deassert rx_np_ok for extended periods, because this can
cause a completion timeout in the Requester. See the PCI Express Base Specification for
more information on the Completion Timeout Mechanism.
X-Ref Target - Figure 3-22
user_clk_out
m_axis_rx_tdata[63:0]
H1H0
H3H2
Non-Posted TLP1
H1H0
Non-Posted TLP2
H3H2
H1H0
D0H2
Posted/Cpl TLP3
m_axis_rx_tready
m_axis_rx_tvalid
m_axis_rx_tlast
rx_np_ok
Figure 3-22:
Receive Interface Non-Posted Throttling
Packet re-ordering allows the user application to optimize the rate at which Non-Posted
TLPs are processed, while continuing to receive and process Posted and Completion
TLPs in a non-blocking fashion. The rx_np_ok signaling restrictions require that the
user application be able to receive and buffer at least three Non-Posted TLPs. This
algorithm describes the process of managing the Non-Posted TLP buffers:
Consider that Non-Posted_Buffers_Available denotes the size of Non-Posted buffer
space available to the user application. The size of the Non-Posted buffer space is
greater than three Non-Posted TLPs. Non-Posted_Buffers_Available is decremented
when Non-Posted TLP is accepted for processing from the core, and is incremented
when Non-Posted TLP is drained for processing by the user application.
For every clock cycle do {
if (Non-Posted_Buffers_Available <= 3) {
if (Valid transaction Start-of-Frame accepted by user application) {
Extract TLP Format and Type from the 1st TLP DW
if (TLP type == Non-Posted) {
Deassert rx_np_ok on the following clock cycle
- or Other optional user policies to stall NP transactions
} else {
}
}
} else { // Non-Posted_Buffers_Available > 3
Assert rx_np_ok on the following clock cycle.
}
}
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Chapter 3: Designing with the Core
•
Receive Request for Non-Posted (Receive Non-Posted Request Enabled,
TRN_ NP_ FC attribute TRUE)
The 7 Series FPGAs Integrated Block for PCI Express allows the user application to
control Flow Control Credit return for the Non-Posted queue using the rx_np_req
signal. When the user application has space in its receiver to receive a Non-Posted
Transaction, it must assert rx_np_req for one clock cycle for every Non-Posted
Transaction that the user application can accept. This enables the integrated block to
present one Non-Posted transaction from its receiver queues to the core transaction
interface, as shown in Figure 3-23 and return one Non-Posted Credit to the connected
Link partner.
X-Ref Target - Figure 3-23
user_clk_out
m_axis_rx_tdata[63:0]
H1H0
D0H2
D2D1
Posted TLP1
D4D3
H1H0
--H2
Non-Posted TLP2
H1H0
D0H2
Posted/Cpl TLP3
D2D1
H1H0
--H2
H1H0
--H2
Non-Posted TLP4 Non-Posted TLP5
m_axis_rx_tready
m_axis_rx_tvalid
m_axis_rx_tlast
rx_np_req
Figure 3-23:
Receive Interface Request for Non-Posted Transaction
The core maintains a count of up to 12 Non-Posted Requests from the user application.
In other words, the core remembers assertions of rx_np_req even if no Non-Posted
TLPs are present in the receive buffer and presents received Non-Posted TLPs to the user
application, if requests have been previously made by the user application. If the core
has no outstanding requests from the user application and received Non-Posted TLPs
are waiting in the receive buffer, received Posted and Completion Transactions pass the
waiting Non-Posted Transactions.
When the user application is ready to accept a Non-Posted TLP, asserting rx_np_req
for one or more cycles causes that number of waiting Non-Posted TLPs to be delivered
at the next available TLP boundary. In other words, any Posted or Completion TLP
currently on the user application interface finishes before waiting Non-Posted TLPs are
presented to the user application. If there are no Posted or Completion TLPs and a
Non-Posted TLP is waiting, asserting rx_np_req causes the Non-Posted TLP to be
presented to the user application. TLPs are delivered to the user application in order
except when you are throttling Non-Posted TLPs, allowing Posted and Completion TLPs
to pass. When the user application starts accepting Non-Posted TLPs again, ordering is
still maintained with any subsequent Posted or Completion TLPs. If the user application
can accept all Non-Posted Transactions as they are received and does not care about
controlling the Flow Control Credit return for the Non-Posted queue, keep this signal
asserted.
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Chapter 3: Designing with the Core
Packet Data Poisoning and TLP Digest on the 64-Bit Receive AXI4-Stream Interface
To simplify logic within the user application, the core performs automatic pre-processing
based on values of TLP Digest (TD) and Data Poisoning (EP) header bit fields on the received
TLP.
All received TLPs with the Data Poisoning bit in the header set (EP = 1) are presented to the
user application. The core asserts the (rx_err_fwd) m_axis_rx_tuser[1] signal for
the duration of each poisoned TLP, as illustrated in Figure 3-24.
X-Ref Target - Figure 3-24
user_clk_out
m_axis_rx_tdata[63:0]
m_axis_rx_tready
m_axis_rx_tvalid
m_axis_rx_tlast
m_axis_rx_tkeep[7:0]
FFh
FFh
(rx_err_fwd) m_axis_rx_tuser[1]
Figure 3-24:
Receive Transaction Data Poisoning
If the TLP Digest bit field in the TLP header is set (TD = 1), the TLP contains an End-to-End
CRC (ECRC). The core performs these operations based on how you configured the core
during core generation. If the Trim TLP Digest option is:
•
On: the core removes and discards the ECRC field from the received TLP and clears the
TLP Digest bit in the TLP header.
•
Off: the core does not remove the ECRC field from the received TLP and presents the
entire TLP including TLP Digest to the user application receiver interface.
See ECRC, page 228 for more information about how to enable the Trim TLP Digest option
during core generation.
ECRC Error on the 64-Bit Receive AXI4-Stream Interface
The 7 Series FPGAs Integrated Block for PCI Express core checks the ECRC on incoming
transaction packets, when ECRC checking is enabled in the core. When it detects an ECRC
error in a transaction packet, the core signals this error by simultaneously asserting
m_axis_rx_tuser[0] (rx_ecrc_err) and m_axis_rx_tlast, as illustrated in
Figure 3-25.
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Chapter 3: Designing with the Core
X-Ref Target - Figure 3-25
user_clk_out
m_axis_rx_tdata[63:0]
m_axis_rx_tready
m_axis_rx_tvalid
m_axis_rx_tlast
m_axis_rx_tkeep[7:0]
FFh
FFh
(rx_ecrc_err) m_axis_rx_tuser[0]
Figure 3-25:
ECRC Error on 64-Bit Receive AXI4-Stream Interface
Packet Base Address Register Hit on the Receive AXI4-Stream Interface
The 7 Series FPGAs Integrated Block for PCI Express in Root Port configuration does not
perform any BAR decoding/filtering.
In Endpoint configuration, the core decodes incoming Memory and I/O TLP request
addresses to determine which Base Address Register (BAR) in the core Type0 configuration
space is being targeted, and indicates the decoded base address on
m_axis_rx_tuser[9:2](rx_bar_hit[7:0]). For each received Memory or I/O TLP, a
minimum of one bit and a maximum of two (adjacent) bits are set to 1b. If the received TLP
targets a 32-bit Memory or I/O BAR, only one bit is asserted. If the received TLP targets a
64-bit Memory BAR, two adjacent bits are asserted. If the core receives a TLP that is not
decoded by one of the BARs (that is, a misdirected TLP), then the core drops it without
notification and it automatically generates an Unsupported Request message. Even if the
core is configured for a 64-bit BAR, the system might not always allocate a 64-bit address,
in which case only onerxbar_hit[7:0] signal is asserted. Overlapping BAR apertures are
not allowed.
Table 3-1 illustrates mapping between rx_bar_hit[7:0] and the BARs, and the
corresponding byte offsets in the core Type0 configuration header.
Table 3-1:
Base Address Register Mapping
rx_bar_hit[x]
m_axis_rx_tuser[x]
BAR
Byte Offset
0
2
0
10h
1
3
1
14h
2
4
2
18h
3
5
3
1Ch
4
6
4
20h
5
7
5
24h
6
8
Expansion ROM BAR
30h
7
9
Reserved
–
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Chapter 3: Designing with the Core
For a Memory or I/O TLP Transaction on the receive interface, (rx_bar_hit[7:0])
m_axis_rx_tuser[9:2] is valid for the entire TLP, starting with the assertion of
m_axis_rx_tvalid, as shown in Figure 3-26. When receiving non-Memory and non-I/O
transactions, signal rx_bar_hit[7:0] is undefined.
X-Ref Target - Figure 3-26
user_clk_out
m_axis_rx_tdata[63:0]
TLP1
TLP2
0000010b
0001100b
m_axis_rx_tready
m_axis_rx_tvalid
m_axis_rx_tlast
(rx_bar_hit[7:0])m_axis_rx_tuser[9:2]
Figure 3-26:
BAR Target Determination Using rx_bar_hit
The (rx_bar_hit[7:0]) m_axis_rx_tuser[9:2] signal enables received Memory
and I/O transactions to be directed to the appropriate destination apertures within the user
application. By utilizing rx_bar_hit[7:0], application logic can inspect only the lower
order Memory and I/O address bits within the address aperture to simplify decoding logic.
Packet Transfer During Link-Down Event on Receive AXI4-Stream Interface
The loss of communication with the link partner is signaled by deassertion of
user_lnk_up. When user_lnk_up is deasserted, it effectively acts as a Hot Reset to the
entire core. For this reason, all TLPs stored inside the core or being presented to the receive
interface are irrecoverably lost. A TLP in progress on the Receive AXI4-Stream interface is
presented to its correct length, according to the Length field in the TLP header. However,
the TLP is corrupt and should be discarded by the user application. Figure 3-27 illustrates
the packet transfer discontinue scenario.
X-Ref Target - Figure 3-27
user_clk_out
user_lnk_up
m_axis_rx_tdata[63:0]
H1H0
D0H2
D2D1
PAD
PAD
original TLP data was lost
m_axis_rx_tready
m_axis_rx_tvalid
m_axis_rx_tlast
Figure 3-27:
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Chapter 3: Designing with the Core
Designing with the 128-Bit Transaction Layer Interface
Note: The transaction interface width and frequency never change with a lane width/speed
upconfigure or downconfigure.
TLP Format in the AXI4-Stream Interface
Data is transmitted and received in Big-Endian order as required by the PCI Express Base
Specification [Ref 2]. See Chapter 2 of the PCI Express Base Specification for detailed
information about TLP packet ordering. Figure 3-28 represents a typical 32-bit addressable
Memory Write Request TLP (as illustrated in Chapter 2 of the specification).
X-Ref Target - Figure 3-28
+0
+1
+2
+3
7 6 5 4 3 2 1 0 7 6 5 4 3 2 1 0 7 6 5 4 3 2 1 0 7 6 5 4 3 2 1 0
Byte 0 >
R
Fmt
x0
Type
R
TC
Rsvd
T E
Attr
D P
Requester ID
Byte 4 >
R
Length
Last DW 1st DW
BE
BE
Tag
Address[31:2]
Byte 8 >
Byte 12 >
Data 0
Byte 16 >
Data 1
Byte 20 >
Data 2
Byte 24 >
TLP Digest
Figure 3-28:
R
PCI Express Base Specification Byte Order
When using the transaction interface, packets are arranged on the entire 128-bit datapath.
Figure 3-29 shows the same example packet on the AXI4-Stream interface. PCIe Byte 0 of
the packet appears on s_axis_tx_tdata[31:24] (transmit) or
m_axis_rx_tdata[31:24] (receive) of the first DWORD, byte 1 on
s_axis_tx_tdata[23:16] or m_axis_rx_tdata[23:16]. The Header section of the
packet consists of either three or four DWORDs, determined by the TLP format and type as
described in section 2.2 of the PCI Express Base Specification.
X-Ref Target - Figure 3-29
[95:64]
[63:32]
AXI Bit
AXI Byte
+15
[127:96]
+14 +13
+12
+11
+10
+9
+8
+7
+6
+5
+4
+3
[31:0]
+2
+1
+0
PCIe Byte
+12
+13
+15
+8
+9
+10
+11
+4
+5
+6
+7
+0
+1
+3
Clock 0
+14
Data DW 0
Clock1
Figure 3-29:
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+2
Header DW 2
Header DW 1
Header DW 0
TLP Digest
Data DW2
Data DW 1
Endpoint Integrated Block Byte Order
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Chapter 3: Designing with the Core
IMPORTANT: Packets sent to the core for transmission must follow the formatting rules for transaction
layer packets (TLPs) as specified in Chapter 2 of the PCI Express Base Specification.
The user application is responsible for ensuring the validity of the packets. The core does
not check that a packet is correctly formed and this can result in transferring a malformed
TLP. The exact fields of a given TLP vary depending on the type of packet being transmitted.
Transmitting Outbound Packets
Basic TLP Transmit Operation
The 7 Series FPGAs Integrated Block for PCI Express core automatically transmits these
types of packets:
•
Completions to a remote device in response to Configuration Space requests.
•
Error-message responses to inbound requests that are malformed or unrecognized by
the core.
Note: Certain unrecognized requests, for example, unexpected completions, can only be
detected by the user application, which is responsible for generating the appropriate response.
The user application is responsible for constructing these types of outbound packets:
•
Memory, Atomic Ops, and I/O Requests to remote devices.
•
Completions in response to requests to the user application, for example, a Memory
Read Request.
When configured as an Endpoint, the core notifies the user application of pending
internally generated TLPs that arbitrate for the transmit datapath by asserting
tx_cfg_req (1b). The user application can choose to give priority to core-generated
TLPs by asserting tx_cfg_gnt (1b) permanently, without regard to tx_cfg_req.
Doing so prevents User-Application-generated TLPs from being transmitted when a
core-generated TLP is pending. Alternatively, the user application can reserve priority
for a user application-generated TLP over core-generated TLPs, by deasserting
tx_cfg_gnt (0b) until the transaction is complete. After the transaction is complete,
the user application can assert tx_cfg_gnt (1b) for at least one clock cycle to allow
the pending core-generated TLP to be transmitted. You must not delay asserting
tx_cfg_gnt indefinitely, because this might cause a completion timeout in the
Requester. See the PCI Express Base Specification for more information on the
Completion Timeout Mechanism.
•
The integrated block does not do any filtering on the Base/Limit registers (Root Port
only). You are responsible for determining if filtering is required. These registers can be
read out of the Type 1 Configuration Header space through the Configuration interface
(see Designing with Configuration Space Registers and Configuration Interface,
page 105).
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Chapter 3: Designing with the Core
Table 2-9, page 16 defines the transmit user application signals. To transmit a TLP, the user
application must perform this sequence of events on the transmit AXI4-Stream interface:
1. The user application logic asserts s_axis_tx_tvalid, and presents the first TLP
Double-Quad Word (DQWORD = 128 bits) on s_axis_tx_tdata[127:0]. If the core
is asserting s_axis_tx_tready, the DQWORD is accepted immediately; otherwise,
the user application must keep the DQWORD presented until the core asserts
s_axis_tx_tready.
2. The user application asserts s_axis_tx_tvalid and presents the remainder of the
TLP DQWORDs on s_axis_tx_tdata[127:0] for subsequent clock cycles (for which
the core asserts s_axis_tx_tready).
3. The user application asserts s_axis_tx_tvalid and s_axis_tx_tlast together
with the last DQWORD data. You must ensure that the strobe field is selected for the
final data cycle to create a packet of length equivalent to the length field in the packet
header. For more information on the s_axis_tx_tkeep[15:0] signaling, see
Table 3-2 and Table 3-3.
4. At the next clock cycle, the user application deasserts s_axis_tx_tvalid to signal
the end of valid transfers on s_axis_tx_tdata[127:0].
This section uses the notation Hn and Dn to denote Header QWn and Data QWn,
respectively. Table 3-2 lists the possible single-cycle packet signaling where
s_axis_tx_tlast is asserted in the same cycle.
Table 3-2:
TX: EOF Scenarios, Single Cycle
s_axis_tx_tdata[127:0]
H3 H2 H1 H0
-- H2 H1 H0
D0 H2 H1 H0
1
1
1
0xFFFF
0x0FFF
0xFFFF
s_axis_tx_tlast
s_axis_tx_tkeep[15:0]
Table 3-3 lists the possible signaling for ending a multicycle packet. If a packet ends in the
lower QW of the data bus, the next packet cannot start in the upper QW of that beat. All
packets must start in the lowest DW of the data bus in a new beat. The
s_axis_tx_tkeep[15:0] signal indicates which DWORD of the data bus contains
end-of-frame (EOF).
Table 3-3:
TX: EOF Scenarios, Multicycle
s_axis_tx_tdata[127:0]
D3 D2 D1 D0
-- D2 D1 D0
-- -- D1 D0
-- -- -- D0
1
1
1
1
0xFFFF
0x0FFF
0x00FF
0x000F
s_axis_tx_tlast
s_axis_tx_tkeep[15:0]
Figure 3-30 illustrates a 3-DW TLP header without a data payload; an example is a 32-bit
addressable Memory Read request. When the user application asserts s_axis_tx_tlast,
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Chapter 3: Designing with the Core
it also places a value of 0x0FFF on s_axis_tx_tkeep[15:0], notifying the core that
only s_axis_tx_tdata[95:0] contains valid data.
X-Ref Target - Figure 3-30
user_clock_out
s_axis_tx_tdata[127:0]
--H2H1H0
s_axis_tx_tready
s_axis_tx_tvalid
s_axis_tx_tlast
s_axis_tx_tkeep[15:0]
0FFFh
(tx_err_fwd) s_axis_tx_tuser[1]
(tx_str) s_axis_tx_tuser[2]
(tx_src_dsc) s_axis_tx_tuser[3]
tx_terr_drop
Figure 3-30:
TLP 3-DW Header without Payload
Figure 3-31 illustrates a 4-DW TLP header without a data payload; an example is a 64-bit
addressable Memory Read request. When the user application asserts s_axis_tx_tlast,
it also places a value of 0xFFFF on s_axis_tx_tkeep[15:0] notifying the core that
s_axis_tx_tdata[127:0] contains valid data and the EOF occurs in the upper-most
DW.
X-Ref Target - Figure 3-31
user_clock_out
s_axis_tx_tdata[127:0]
H3H2H1H0
s_axis_tx_tready
s_axis_tx_tvalid
s_axis_tx_tlast
s_axis_tx_tkeep[15:0]
FFFFh
(tx_err_fwd) s_axis_tx_tuser[1]
(tx_str) s_axis_tx_tuser[2]
(tx_src_dsc) s_axis_tx_tuser[3]
Figure 3-31:
TLP with 4-DW Header without Payload
Figure 3-32 illustrates a 3-DW TLP header with a data payload; an example is a 32-bit
addressable Memory Write request. When the user application asserts s_axis_tx_tlast,
it also puts a value of 0x0FFF on s_axis_tx_tkeep[15:0] notifying the core that
s_axis_tx_tdata[95:0] contains valid data and the EOF occurs in DWORD 2.
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Chapter 3: Designing with the Core
X-Ref Target - Figure 3-32
user_clk_out
s_axis_tx_tdata[127:0]
D0H2H1H0
D4D3D2D1
--D7D6D5
s_axis_tx_tready
s_axis_tx_tvalid
s_axis_tx_tlast
s_axis_tx_tkeep[15:0]
FFFFh
0FFFh
(tx_err_fwd)s_axis_tx_tuser[1]
(tx_str)s_axis_tx_tuser[2]
(tx_src_dsc)s_axis_tx_tuser[3]
tx_terr_drop
Figure 3-32:
TLP with 3-DW Header with Payload
Figure 3-33 illustrates a 4-DW TLP header with a data payload. When the user application
asserts s_axis_tx_tlast, it also places a value of 0x00FF on
s_axis_tx_tkeep[15:0], notifying the core that only s_axis_tx_tdata[63:0]
contains valid data.
X-Ref Target - Figure 3-33
user_clock_out
s_axis_tx_tdata[127:0]
H3H2H1H0
D3D2D1D0
----DnDn-1
s_axis_tx_tready
s_axis_tx_tvalid
s_axis_tx_tlast
s_axis_tx_tkeep[15:0]
FFFFh
00FFh
(terr_fwd) s_axis_tx_tuser[1]
(str) s_axis_tx_tuser[2]
(src_dsc) s_axis_tx_tuser[3]
Figure 3-33:
TLP with 4-DW Header with Payload
Presenting Back-to-Back Transactions on the Transmit Interface
The user application can present back-to-back TLPs on the transmit AXI4-Stream interface
to maximize bandwidth utilization. Figure 3-34 illustrates back-to-back TLPs presented on
the transmit interface, with the restriction that all TLPs must start in the lowest DW of the
data bus [31:0]. The user application keeps s_axis_tx_tvalid asserted and presents a
new TLP on the next clock cycle after asserting s_axis_tx_tlast for the previous TLP.
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Chapter 3: Designing with the Core
X-Ref Target - Figure 3-34
user_clk_out
s_axis_tx_tdata[127:0]
H4H2H1H0
--D2D1D0
TLP1
H3H2H1H0
------D0
TLP2
s_axis_tx_tready
s_axis_tx_tvalid
s_axis_tx_tlast
s_axis_tx_tkeep[15:0]
FFFFh
Figure 3-34:
0FFFh
FFFFh
000Fh
Back-to-Back Transaction on the Transmit Interface
Source Throttling on the Transmit Datapath
The AXI4-Stream interface lets the user application throttle back if it has no data to present
on s_axis_tx_tdata[127:0]. When this condition occurs, the user application
deasserts s_axis_tx_tvalid, which instructs the core AXI4-Stream interface to
disregard data presented on s_axis_tx_tdata[127:0]. Figure 3-35 illustrates the
source throttling mechanism, where the user application does not have data to present
every clock cycle, and therefore must deassert s_axis_tx_tvalid during these cycles.
X-Ref Target - Figure 3-35
user_clock_out
s_axis_tx_tdata[127:0]
H3H2H1H0
D3D2D1D0
D7D6D5D4
D11D10D9D8
s_axis_tx_tready
s_axis_tx_tvalid
s_axis_tx_tlast
s_axis_tx_tkeep[15:0]
FFFFh
Figure 3-35:
Source Throttling on the Transmit Datapath
Destination Throttling of the Transmit Datapath
The core AXI4-Stream interface throttles the transmit user application if there is no space
left for a new TLP in its transmit buffer pool. This can occur if the link partner is not
processing incoming packets at a rate equal to or greater than the rate at which the user
application is presenting TLPs. Figure 3-36 illustrates the deassertion of
s_axis_tx_tready to throttle the user application when the internal transmit buffers of
the core are full. If the core needs to throttle the user application, it does so after the
current packet has completed. If another packet starts immediately after the current packet,
the throttle occurs immediately after s_axis_tx_tlast.
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X-Ref Target - Figure 3-36
user_clk_out
s_axis_tx_tdata[127:0]
H3H2H1H0
D3D2D1D0
----D5D4
TLP 1
D0H2H1H0
------D1
TLP 2
s_axis_tx_tready
s_axis_tx_tvalid
s_axis_tx_tlast
s_axis_tx_tkeep[15:0]
tx_buf_av
00h
Figure 3-36:
FFFFh
00FFh
02h
00h
FFFFh
000Fh
02h
00h
Destination Throttling of the Endpoint Transmit Interface
If the core transmit AXI4-Stream interface accepts the start of a TLP by asserting
s_axis_tx_tready, it is guaranteed to accept the complete TLP with a size up to the
value contained in the Max_Payload_Size field of the PCI Express Device Capability Register
(offset 04H). To stay compliant with the PCI Express Base Specification [Ref 2], you should
not violate the Max_Payload_Size field of the PCI Express Device Control Register (offset
08H). The core transmit AXI4-Stream interface deasserts s_axis_tx_tready only under
these conditions:
•
After it has accepted the TLP completely and has no buffer space available for a new
TLP.
•
When the core is transmitting an internally generated TLP (Completion TLP because of
a Configuration Read or Write, error Message TLP or error response as requested by
the user application on the cfg_err interface), after it has been granted use of the
transmit datapath by the user application, by assertion of tx_cfg_gnt, the core
subsequently asserts s_axis_tx_tready after transmitting the internally generated
TLP.
•
When the Power State field in the Power Management Control/Status Register (offset
0x4) of the PCI Power Management Capability Structure is changed to a non-D0 state,
any ongoing TLP is accepted completely and s_axis_tx_tready is subsequently
deasserted, disallowing the user application from initiating any new transactions for
the duration that the core is in the non-D0 power state.
On deassertion of s_axis_tx_tready by the core, the user application needs to hold all
control and data signals until the core asserts s_axis_tx_tready.
Discontinuing Transmission of Transaction by Source
The core AXI4-Stream interface lets the user application terminate transmission of a TLP by
asserting (tx_src_dsc) s_axis_tx_tuser[3]. Both s_axis_tx_tvalid and
s_axis_tx_tready must be asserted together with tx_src_dsc for the TLP to be
discontinued. The signal tx_src_dsc must not be asserted at the beginning of a TLP. It can
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Chapter 3: Designing with the Core
be asserted on any cycle after the first beat of a new TLP up to and including the assertion
of s_axis_tx_tlast. Asserting tx_src_dsc has no effect if no TLP transaction is in
progress on the transmit interface. Figure 3-37 illustrates the user application
discontinuing a packet using tx_src_dsc. Asserting s_axis_tx_tlast together with
tx_src_dsc is optional.
If streaming mode is not used, s_axis_tx_tuser[2](tx_str)= 0b, and the packet is
discontinued, then the packet is discarded before being transmitted on the serial link. If
streaming mode is used (tx_str = 1b), the packet is terminated with the EDB symbol on
the serial link.
X-Ref Target - Figure 3-37
user_clock_out
s_axis_tx_tdata[63:0]
H1H0
D0H2
D2D1
D4D3
s_axis_tx_tready
s_axis_tx_tvalid
s_axis_tx_tlast
s_axis_tx_tkeep[7:0]
FFh
(tx_src_dsc) s_axis_tx_tuser[3]
Figure 3-37:
Source Driven Transaction Discontinue on the Transmit Interface
Discarding of Transaction by Destination
The core transmit AXI4-Stream interface discards a TLP for three reasons:
•
The PCI Express Link goes down.
•
Presented TLP violates the Max_Payload_Size field of the Device Capability Register
(offset 04H) for PCI Express. It is your responsibility to not violate the
Max_Payload_Size field of the Device Control Register (offset 08H).
•
s_axis_tx_tuser[2](tx_str) is asserted and data is not presented on
consecutive clock cycles, that is, s_axis_tx_tvalid is deasserted in the middle of a
TLP transfer.
When any of these occur, the transmit AXI4-Stream interface continues to accept the
remainder of the presented TLP and asserts tx_err_drop no later than the third clock
cycle following the EOF of the discarded TLP. Figure 3-38 illustrates the core signaling that
a packet was discarded using tx_err_drop.
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X-Ref Target - Figure 3-38
user_clk_out
s_axis_tx_tdata[127:0]
TLP1
TLP2
s_axis_tx_tready
s_axis_tx_tvalid
s_axis_tx_tlast
tx_terr_drop
Figure 3-38:
Discarding of Transaction by Destination on the Transmit Interface
Packet Data Poisoning on the Transmit AXI4-Stream Interface
The user application uses either of these two mechanisms to mark the data payload of a
transmitted TLP as poisoned:
•
Set EP = 1 in the TLP header. This mechanism can be used if the payload is known to be
poisoned when the first DWORD of the header is presented to the core on the
AXI4-Stream interface.
•
Assert s_axis_tx_tuser[1](tx_err_fwd) for at least one valid data transfer cycle
any time during the packet transmission, as shown in Figure 3-39. This causes the core
to set EP = 1 in the TLP header when it transmits the packet onto the PCI Express fabric.
This mechanism can be used if the user application does not know whether a packet
could be poisoned at the start of packet transmission. Use of tx_err_fwd is not
supported for packets when s_axis_tx_tuser[2] (tx_str) is asserted (streamed
transmit packets). In streaming mode, you can optionally discontinue the packet if it
becomes corrupted. See Discontinuing Transmission of Transaction by Source, page 52
for details on discontinuing packets.
X-Ref Target - Figure 3-39
user_clock_out
s_axis_tx_tdata[127:0]
H3H2H1H0
D3D2D1D0
D7D6D5D4
----D9D8
s_axis_tx_tready
s_axis_tx_tvalid
s_axis_tx_tlast
s_axis_tx_tkeep[15:0]
FFFFh
00FFh
(tx_err_fwd) s_axis_tx_tuser[1]
Figure 3-39:
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Streaming Mode for Transactions on the Transmit Interface
The 7 Series FPGAs Integrated Block for PCI Express core allows the user application to
enable Streaming (cut-through) mode for transmission of a TLP, when possible, to reduce
latency of operation. To enable this feature, the user application must assert
s_axis_tx_tuser[2](tx_str)for the entire duration of the transmitted TLP. In
addition, the user application must present valid frames on every clock cycle until the final
cycle of the TLP. In other words, the user application must not deassert
s_axis_tx_tvalid for the duration of the presented TLP. Source throttling of the
transaction while in streaming mode of operation causes the transaction to be dropped
(tx_err_drop is asserted) and a nullified TLP to be signaled on the PCI Express link.
Figure 3-40 illustrates the streaming mode of operation, where the first TLP is streamed and
the second TLP is dropped because of source throttling.
X-Ref Target - Figure 3-40
user_clk_out
s_axis_tx_tdata[127:0]
TLP1
TLP2
s_axis_tx_tready
s_axis_tx_tvalid
s_axis_tx_tlast
(tx_str) s_axis_tx_tuser[2]
tx_terr_drop
Figure 3-40:
Streaming Mode on the Transmit Interface
Using ECRC Generation (128-Bit Interface)
The integrated block supports automatic ECRC generation. To enable this feature, the user
application must assert (tx_ecrc_gen) s_axis_tx_tuser[0] at the beginning of a
TLP on the transmit AXI4-Stream interface. This signal can be asserted through the duration
of the packet, if desired. If the outgoing TLP does not already have a digest, the core
generates and appends one and sets the TD bit. There is a single-clock cycle deassertion of
s_axis_tx_tready at the end of packet to allow for insertion of the digest. Figure 3-41
illustrates ECRC generation operation.
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Chapter 3: Designing with the Core
X-Ref Target - Figure 3-41
user_clk_out
s_axis_tx_tdata[127:0]
H4H2H1H0
--D2D1D0
TLP1
H3H2H1H0
------D0
TLP2
s_axis_tx_tready
s_axis_tx_tvalid
s_axis_tx_tlast
s_axis_tx_tkeep[15:0]
FFFFh
0FFFh
FFFFh
000Fh
(tx_ecrc_gen) s_axis_tx_tuser[0]
Figure 3-41:
ECRC Generation Waveforms (128-Bit Interface)
Receiving Inbound Packets
Basic TLP Receive Operation
Table 2-10, page 19 defines the receive AXI4-Stream interface signals. This sequence of
events must occur on the receive AXI4-Stream interface for the Endpoint core to present a
TLP to the user application logic:
1. When the user application is ready to receive data, it asserts m_axis_rx_tready.
2. When the core is ready to transfer data, the core asserts (rx_is_sof[4])
m_axis_rx_tuser[14] and presents the first complete TLP DQWORD on
m_axis_rx_tdata[127:0].
3. The core then deasserts (rx_is_sof[4]) m_axis_rx_tuser[14], keeps
m_axis_rx_tvalid asserted, and presents TLP DQWORDs on
m_axis_rx_tdata[127:0] on subsequent clock cycles (provided the user
application logic asserts m_axis_rx_tready). Signal (rx_is_eof[4])
m_axis_rx_tuser[21] is asserted to signal the end of a TLP.
4. If no further TLPs are available at the next clock cycle, the core deasserts
m_axis_rx_tvalid to signal the end of valid transfers on
m_axis_rx_tdata[127:0].
Note: The user application should ignore any assertions of rx_is_sof, rx_is_eof, and
m_axis_rx_tdata unless m_axis_rx_tvalid is concurrently asserted. Signal
m_axis_rx_tvalid never deasserts mid-packet.
Signal (rx_is_sof[4:0]) m_axis_rx_tuser[14:10] indicates whether or not a new
packet has been started in the data stream, and if so, where the first byte of the new packet
is located. Because new packets are at a minimum of three DWORDs in length for PCI
Express, there is always, at most, one new packet start for a given clock cycle in the 128-bit
interface.
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Table 3-4:
rx_is_sof Signal Description
Bit
Description
rx_is_sof[3:0]
Binary encoded byte location of start-of-frame (SOF): 4'b0000 = byte
0, 4'b1111 = byte 15
rx_is_sof[4]
Assertion indicates a new packet has been started in the current RX
data.
The rx_is_sof[2:0] signal is always deasserted for the 128-bit interface; you can
decode rx_is_sof[3:2] to determine in which DWORD the EOF occurs.
•
rx_is_sof = 5'b10000 - SOF located at byte 0 (DWORD 0)
•
rx_is_sof = 5'b11000 - SOF located at byte 8 (DWORD 2)
•
rx_is_sof = 5'b0XXXX - SOF not present
The (rx_is_eof[4:0]) m_axis_rx_tuser[21:17] signal indicates whether or not a
current packet is ending in the data stream, and if so, where the last byte of the current
packet is located. Because packets are at a minimum of three DWORDs in length for PCI
Express, there is always, at most, one packet ending for a given clock cycle in the 128-bit
interface.
Table 3-5:
rx_is_eof Signal Description
Bit
rx_is_eof[3:0]
rx_is_eof[4]
Description
Binary encoded byte location of EOF: 4'b0000 = byte 0, 4'b1111 =
byte 15
Assertion indicates a packet is ending in the current RX data.
The rx_is_eof[1:0] signal is always asserted for the 128-bit interface; you can decode
rx_is_eof[3:2] to determine in which DWORD the EOF occurs. These rx_is_eof
values are valid for PCI Express:
•
rx_is_eof = 5'b10011 - EOF located at byte 3 (DWORD 0)
•
rx_is_eof = 5'b10111 - EOF located at byte 7 (DWORD 1)
•
rx_is_eof = 5'b11011 - EOF located at byte 11 (DWORD 2)
•
rx_is_eof = 5'b11111 - EOF located at byte 15 (DWORD 3)
•
rx_is_eof = 5'b0XXXX - EOF not present
Table 3-6 through Table 3-9 use the notation Hn and Dn to denote Header DWORD n and
Data DWORD n, respectively. Table 3-6 list the signaling for all the valid cases where a
packet can start and end within a single beat (single-cycle TLP).
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Chapter 3: Designing with the Core
Table 3-6:
Single-Cycle SOF and EOF Scenarios (Header and Header with Data)
m_axis_rx_tdata[127:0]
H3 H2 H1 H0
-- H2 H1 H0
D0 H2 H1 H0
1b
1b
1b
0000b
0000b
0000b
1b
1b
1b
1111b
1011b
1111b
rx_is_sof[4]
rx_is_sof[3:0]
rx_is_eof[4]
rx_is_eof[3:0]
Table 3-7 lists the signaling for all multicycle, non-straddled TLP SOF scenarios.
Table 3-7:
Multicycle, Non-Straddled SOF Scenarios
m_axis_rx_tdata[127:0]
H3 H2 H1 H0(1)
D0 H2 H1 H0(2)
H1 H0 -- --(3)
1b
1b
1b
0000b
0000b
1000b
0b
0b
0b
xxxxb
xxxxb
xxxxb
rx_is_sof[4]
rx_is_sof[3:0]
rx_is_eof[4]
rx_is_eof[3:0]
Notes:
1. Data begins on the next clock cycle.
2. Data continues on the next clock cycle.
3. Remainder of header and possible data on the next clock cycle.
Table 3-8 lists the possible signaling for ending a multicycle packet. If a packet ends in the
lower QWORD of the data bus, the next packet can start in the upper QWORD of that beat
(see Straddle cases, Table 3-9). rx_is_eof[3:2] indicates which DW the EOF occurs.
Table 3-8:
Receive - EOF Scenarios (Data)
m_axis_rx_tdata[127:0]
rx_is_sof[4]
rx_is_sof[3:0]
rx_is_eof[4]
rx_is_eof[3:0]
D3 D2 D1 D0
-- D2 D1 D0
-- -- D1 D0
-- -- -- D0
0b
0b
0b
0b
0000b
0000b
0000b
0000b
1b
1b
1b
1b
1111b
1011b
0111b
0011b
Table 3-9 lists the possible signaling for a straddled data transfer beat. A straddled data
transfer beat occurs when one packet ends in the lower QWORD and a new packet starts in
the upper QWORD of the same cycle. Straddled data transfers only occur in the receive
direction.
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Chapter 3: Designing with the Core
Table 3-9:
Receive - Straddle Cases SOF and EOF
m_axis_rx_tdata[127:0]
rx_is_sof[4]
rx_is_sof[3:0]
rx_is_eof[4]
rx_is_eof[3:0]
H1 H0 Dn Dn–1
H1 H0 -- Dn
1b
1b
1000b
1000b
1b
1b
0111b
0011b
Figure 3-42 shows a 3-DWORD TLP header without a data payload; an example is a 32-bit
addressable Memory Read request. When the core asserts rx_is_eof[4], it also places a
value of 1011b on rx_is_eof[3:0], notifying you that EOF occurs on byte 11
(DWORD 2) and only m_axis_rx_tdata[95:0] contains valid data.
X-Ref Target - Figure 3-42
user_clk_out
m_axis_rx_tdata[127:0]
--H2H1H0
m_axis_rx_tready
m_axis_rx_tvalid
(rx_err_fwd)m_axis_rx_tuser[1]
(rx_bar_hit[7:0])m_axis_rx_tuser[9:2]
(rx_is_sof[4:0])m_axis_rx_tuser[14:10]
10000b
SOF H0
(rx_is_eof[4:0])m_axis_rx_tuser[21:17]
11011b
EOF H2
rx_np_ok
Figure 3-42:
TLP 3-DWORD Header without Payload
Figure 3-43 shows a 4-DWORD TLP header without a data payload. When the core asserts
(rx_is_eof[4]) m_axis_rx_tuser[21], it also places a value of 1111b on
(rx_is_eof[3:0]) m_axis_rx_tuser[20:17], notifying you that the EOF occurs on
byte 15 (DWORD 3) and m_axis_rx_tdata[127:0] contains valid data.
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Chapter 3: Designing with the Core
X-Ref Target - Figure 3-43
user_clk_out
m_axis_rx_tdata[127:0]
H3H2H1H0
m_axis_rx_tready
m_axis_rx_tvalid
(rx_err_fwd) m_axis_rx_tuser[1]
(rx_bar_hit[7:0]) m_axis_rx_tuser[9:2]
(rx_is_sof[4:0]) m_axis_rx_tuser[14:10]
10000b
SOF H0
(rx_is_eof[4:0]) m_axis_rx_tuser[21:17]
11111b
EOF H3
Figure 3-43:
TLP 4-DWORD Header without Payload
Figure 3-44 shows a 3-DW TLP header with a data payload; an example is a 32-bit
addressable Memory Write request. When the core asserts (rx_is_eof[4])
m_axis_rx_tuser[21], it also places a value of 1111b on (rx_is_eof[3:0])
m_axis_rx_tuser[20:17], notifying you that EOF occurs on byte 15 (DWORD 3) and
m_axis_rx_tdata[127:0] contains valid data.
X-Ref Target - Figure 3-44
user_clock_out
m_axis_rx_tdata[127:0]
D0H2H1H0
D4D3D2D1
10000b
00000b
m_axis_rx_tready
m_axis_rx_tvalid
(rx_err_fwd) m_axis_rx_tuser[1]
(rx_bar_hit[7:0]) m_axis_rx_tuser[9:2]
(rx_is_sof[4:0]) m_axis_rx_tuser[14:10]
SOF H0
(rx_is_eof[4:0]) m_axis_rx_tuser[21:17]
00000b
11111b
EOF D4
Figure 3-44:
TLP 3-DWORD Header with Payload
Figure 3-45 shows a 4-DWORD TLP header with a data payload; an example is a 64-bit
addressable Memory Write request. When the core asserts (rx_is_eof[4])
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Chapter 3: Designing with the Core
m_axis_rx_tuser[21], it also places a value of 0011b on (rx_is_eof[3:0])
m_axis_rx_tuser[20:17], notifying you that EOF occurs on byte 3 (DWORD 0) and only
m_axis_rx_tdata[31:0] contains valid data.
X-Ref Target - Figure 3-45
user_clock_out
m_axis_rx_tdata[127:0]
H3H2H1H0
D3D2D1D0
------D4
m_axis_rx_tready
m_axis_rx_tvalid
(rx_err_fwd)m_axis_rx_tuser[1]
(rx_bar_hit[7:0])m_axis_rx_tuser[9:2]
00000110b
(rx_is_sof[4:0])m_axis_rx_tuser[14:10]
10000b
00000b
SOF H0
(rx_is_eof[4:0])m_axis_rx_tuser[21:17]
00000b
10011b
EOF D4
rx_np_ok
Figure 3-45:
TLP 4-DWORD Header with Payload
Throttling the Datapath on the Receive Interface
The user application can stall the transfer of data from the core at any time by deasserting
m_axis_rx_tready. If you deassert m_axis_rx_tready while no transfer is in progress
and if a TLP becomes available, the core asserts m_axis_rx_tvalid and
(rx_is_sof[4]) m_axis_rx_tuser[14] and presents the first TLP DQWORD on
m_axis_rx_tdata[127:0]. The core remains in this state until the you assert
m_axis_rx_tready to signal the acceptance of the data presented on
m_axis_rx_tdata[127:0]. At that point, the core presents subsequent TLP DQWORDs
as long as m_axis_rx_tready remains asserted. If you deassert m_axis_rx_tready
during the middle of a transfer, the core stalls the transfer of data until you assert
m_axis_rx_tready again. There is no limit to the number of cycles you can keep
m_axis_rx_tready deasserted. The core pauses until the user application is again ready
to receive TLPs.
Figure 3-46 illustrates the core asserting m_axis_rx_tvalid and (rx_is_sof[4])
m_axis_rx_tuser[14] along with presenting data on m_axis_rx_tdata[127:0]. The
user application logic inserts wait states by deasserting m_axis_rx_tready. The core
does not present the next TLP DQWORD until it detects m_axis_rx_tready assertion.
The user application logic can assert or deassert m_axis_rx_tready as required to
balance receipt of new TLP transfers with the rate of TLP data processing inside the
application logic.
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Chapter 3: Designing with the Core
X-Ref Target - Figure 3-46
user_clock_out
m_axis_rx_tdata[127:0]
H3H2H1H0
D3D2D1D0
D7D6D5D4
----D9D8
m_axis_rx_tready
m_axis_rx_tvalid
(rx_is_sof[4:0])m_axis_rx_tuser[14:10]
10000b
00000b
SOF H0
(rx_is_eof[4:0])m_axis_rx_tuser[21:17]
00000b
10111b
EOF D9
Figure 3-46:
User Application Throttling Receive TLP
Receiving Back-to-Back Transactions on the Receive Interface
The user application logic must be designed to handle presentation of back-to-back TLPs
on the receive AXI4-Stream interface by the core. The core can assert (rx_is_sof[4])
m_axis_rx_tuser[14] for a new TLP at the clock cycle after (rx_is_eof[4])
m_axis_rx_tuser[21] assertion for the previous TLP. Figure 3-47 illustrates
back-to-back TLPs presented on the receive interface.
X-Ref Target - Figure 3-47
user_clk_out
m_axis_rx_tdata[127:0]
D0H2H1H0
D4D3D2D1
--D7D6D5
D0H2H1H0
TLP1
D4D3D2D1
------D5
TLP2
m_axis_rx_tready
m_axis_rx_tvalid
(rx_is_sof[4:0])m_axis_rx_tuser[14:10]
00000b
10000b
00000b
SOF H0
(rx_is_eof[4:0])m_axis_rx_tuser[21:17]
00000b
10000b
SOF H0
11011b
00000b
EOF D7
Figure 3-47:
00000b
10011b
00000b
EOF D5
Receive Back-to-Back Transactions
If the user application cannot accept back-to-back packets, it can stall the transfer of the
TLP by deasserting m_axis_rx_tready as discussed in the Throttling the Datapath on the
Receive Interface section. Figure 3-48 shows an example of using m_axis_rx_tready to
pause the acceptance of the second TLP.
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X-Ref Target - Figure 3-48
user_clk_out
m_axis_rx_tdata[127:0]
D0H2H1H0D4D3D2D1
H3H2H1H0
TLP1
D3D2D1D0
TLP2
m_axis_rx_tready
m_axis_rx_tvalid
(rx_is_sof[4:0])m_axis_rx_tuser[14:10]
00000b
10000b 00000b
00000b
00000b 00000b
SOF H0
SOF H0
(rx_is_eof[4:0])m_axis_rx_tuser[21:17]
10000b
11111b
00000b
11111b 00000b
EOF D4
Figure 3-48:
EOF D3
User Application Throttling Back-to-Back TLPs
Receiving Straddled Packets on the Receive AXI4-Stream Interface
The user application logic must be designed to handle presentation of straddled TLPs on
the receive AXI4-Stream interface by the core. The core can assert (rx_is_sof[4])
m_axis_rx_tuser[14] for a new TLP on the same clock cycle as (rx_is_eof[4])
m_axis_rx_tuser[21] for the previous TLP, when the previous TLP ends in the lower
QWORD. Figure 3-49 illustrates straddled TLPs presented on the receive interface.
X-Ref Target - Figure 3-49
user_clk_out
m_axis_rx_tdata[127:0]
D0H2H1H0
H1H0--D1
------H2
10000b
11000b
00000b
m_axis_rx_tready
m_axis_rx_tvalid
(rx_is_sof[4:0]) m_axis_rx_tuser[14:10]
SOF H0
(rx_is_eof[4:0]) m_axis_rx_tuser[21:17]
00011b
SOF H0
10011b
EOF D1
Figure 3-49:
10011b
EOF H2
Receive Straddled Transactions
In Figure 3-49, the first packet is a 3-DWORD packet with 64 bits of data and the second
packet is a 3-DWORD packet that begins on the lower QWORD portion of the bus. In the
figure, assertion of (rx_is_eof[4]) m_axis_rx_tuser[21] and(rx_is_eof[3:0])
m_axis_rx_tuser[20:17] = 0011b indicates that the EOF of the previous TLP occurs in
bits [31:0].
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Packet Re-ordering on the Receive AXI4-Stream Interface
Transaction processing in the core receiver is fully compliant with the PCI transaction
ordering rules. The transaction ordering rules allow Posted and Completion TLPs to bypass
blocked Non-Posted TLPs.
The 7 Series FPGAs Integrated Block for PCI Express provides two mechanisms for user
applications to manage their Receiver Non-Posted Buffer space. The first of the two
mechanisms, Receive Non-Posted Throttling, is the use of rx_np_ok to prevent the core
from presenting more than two Non-Posted requests after deassertion of the rx_np_ok
signal. The second mechanism, Receive Request for Non-Posted, allows user-controlled Flow
Control of the Non-Posted queue, using the rx_np_req signal.
The Receive Non-Posted Throttling mechanism assumes that the user application normally
has space in its receiver for non-Posted TLPs and the user application would throttle the
core specifically for Non-Posted requests. The Receive Request for Non-Posted mechanism
assumes that the user application requests the core to present a Non-Posted TLP as and
when it has space in its receiver. The two mechanisms are mutually exclusive, and only one
can be active for a design. This option must be selected while generating and customizing
the core. When the Receive Non-Posted Request option is selected in the Advanced
Settings, the Receive Request for Non-Posted mechanism is enabled and any assertion/
deassertion of rx_np_ok is ignored and vice-versa. The two mechanisms are described in
further detail in the next subsections.
•
Receive Non-Posted Throttling (Receive Non-Posted Request Disabled)
If the user application can receive Posted and Completion Transactions from the core,
but is not ready to accept Non-Posted Transactions, the user application can deassert
rx_np_ok, as shown in Figure 3-50. The user application must deassert rx_np_ok at
least one clock cycle before (rx_is_eof[4]) m_axis_rx_tuser[21] of the
second-to-last Non-Posted TLP the user application can accept. When rx_np_ok is
deasserted, received Posted and Completion Transactions pass Non-Posted
Transactions. After the user application is ready to accept Non-Posted Transactions, it
must reassert rx_np_ok. Previously bypassed Non-Posted Transactions are presented
to the user application before other received TLPs.
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X-Ref Target - Figure 3-50
user_clk_out
m_axis_rx_tdata[127:0]
H3H2H1H0
H3H2H1H0
Non-Posted TLP1
Non-Posted TLP2
D0H2H1H0
Posted/Cpl TLP3
m_axis_rx_tready
m_axis_rx_tvalid
(rx_is_sof[4:0])
m_axis_rx_tuser[14:0]
10000b
10000b
SOF H0
SOF H0
(rx_is_eof[4:0])
m_axis_rx_tuser[21:17]
11111b
11111b
EOF H3
EOF H3
10000b
SOF H0
11111b
EOF D0
rx_np_ok
Figure 3-50:
Receive Interface Non-Posted Throttling
Packet re-ordering allows the user application to optimize the rate at which Non-Posted
TLPs are processed, while continuing to receive and process Posted and Completion
TLPs in a non-blocking fashion. The rx_np_ok signaling restrictions require that the
user application be able to receive and buffer at least three Non-Posted TLPs. This
algorithm describes the process of managing the Non-Posted TLP buffers:
Consider that Non-Posted_Buffers_Available denotes the size of Non-Posted buffer
space available to user application. The size of the Non-Posted buffer space is greater
than three Non-Posted TLPs. Non-Posted_Buffers_Available is decremented when a
Non-Posted TLP is accepted for processing from the core, and is incremented when the
Non-Posted TLP is drained for processing by the user application.
For every clock cycle do {
if (Non-Posted_Buffers_Available <= 3) {
if (Valid transaction Start-of-Frame accepted by user application) {
Extract TLP Format and Type from the 1st TLP DW
if (TLP type == Non-Posted) {
Deassert rx_np_ok on the following clock cycle
- or Other optional user policies to stall NP transactions
} else {
}
}
} else { // Non-Posted_Buffers_Available > 3
Assert rx_np_ok on the following clock cycle.
}
}
•
Receive Request for Non-Posted (Receive Non-Posted Request Enabled)
The 7 Series FPGAs Integrated Block for PCI Express allows the user application to
control Flow Control Credit return for the Non-Posted queue using the rx_np_req
signal. When the user application has space in its receiver to receive a Non-Posted
Transaction, it must assert rx_np_req for one clock cycle for every Non-Posted
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Chapter 3: Designing with the Core
Transaction that the user application can accept. This enables the integrated block to
present one Non-Posted transaction from its receiver queues to the core transaction
interface, as shown in Figure 3-51 and return one Non-Posted Credit to the connected
Link partner.
X-Ref Target - Figure 3-51
user_clk_out
m_axis_rx_tdata[127:0]
D0H2H1H0D4D3D2D1 --H2H1H0 D0H2H1H0 ----D2D1
Posted TLP1
Posted/Cpl TLP3
Non-Posted TLP2
H3H2H1H0 --H2H1H0
Non-Posted TLP5
Non-Posted TLP4
m_axis_rx_tready
m_axis_rx_tvalid
(rx_is_sof[4:0]) m_axis_rx_tuser[14:10]
10000b 00000b 10000b 10000b 00000b 00000b 10000b 10000b
SOF H0
(rx_is_eof[4:0]) m_axis_rx_tuser[21:17]
SOF H0 SOF H0
SOF H0 SOF H0
00011b 11111b 11011b 00011b 10111b 00011b 11111b 11011b
EOF D4 EOF H2
EOF D2
EOF H3 EOF H2
rx_np_req
Figure 3-51:
Receive Interface Request for Non-Posted Transaction
The 7 Series Integrated Block for PCIe maintains a count of up to 12 Non-Posted
Requests from the user application. In other words, the core remembers assertions of
rx_np_req even if no Non-Posted TLPs are present in the receive buffer and presents
received Non-Posted TLPs to the user application, if requests have been previously
made by the user application. If the core has no outstanding requests from the user
application and received Non-Posted TLPs are waiting in the receive buffer, received
Posted and Completion Transactions pass the waiting Non-Posted Transactions. After
the user application is ready to accept a Non-Posted TLP, asserting rx_np_req for one
or more cycles causes that number of waiting Non-Posted TLPs to be delivered at the
next available TLP boundary. In other words, any Posted or Completion TLP currently on
the user application interface finishes before waiting Non-Posted TLPs are presented to
the user application. If there are no Posted or Completion TLPs being presented and a
Non-Posted TLP is waiting, assertion of rx_np_req causes the Non-Posted TLP to be
presented to the user application. TLPs are delivered to the user application in order
except when you are throttling Non-Posted TLPs, allowing Posted and Completion TLPs
to pass. When you start accepting Non-Posted TLPs again, ordering is still maintained
with any subsequent Posted or Completion TLPs. If the user application can accept all
Non-Posted Transactions as they are received and does not care about controlling the
Flow Control Credit return for the Non-Posted queue, keep this signal asserted.
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Chapter 3: Designing with the Core
Packet Data Poisoning and TLP Digest on the 128-Bit Receive AXI4-Stream Interface
To simplify logic within the user application, the core performs automatic pre-processing
based on values of TLP Digest (TD) and Data Poisoning (EP) header bit fields on the received
TLP.
All received TLPs with the Data Poisoning bit in the header set (EP = 1) are presented. The
core asserts the (rx_err_fwd) m_axis_rx_tuser[1] signal for the duration of each
poisoned TLP, as illustrated in Figure 3-52.
X-Ref Target - Figure 3-52
user_clk_out
m_axis_rx_tdata[127:0]
D0H2H1H0
D4D3D2D1
--D7D6D5
m_axis_rx_tready
m_axis_rx_tvalid
(rx_err_fwd)m_axis_rx_tuser[1]
(rx_is_sof[4:0])m_axis_rx_tuser[14:10]
00000b
10000b
00000b
SOF H0
(rx_is_eof[4:0])m_axis_rx_tuser[21:17]
00000b
11011b
00000b
EOF D7
Figure 3-52:
Receive Transaction Data Poisoning
If the TLP Digest bit field in the TLP header is set (TD = 1), the TLP contains an End-to-End
CRC (ECRC). The core performs these operations based on how you configured the core
during core generation. If the Trim TLP Digest option is:
•
On: The core removes and discards the ECRC field from the received TLP and clears the
TLP Digest bit in the TLP header.
•
Off: The core does not remove the ECRC field from the received TLP and presents the
entire TLP including TLP Digest to the user application receiver interface.
See ECRC, page 228 for more information about how to enable the Trim TLP Digest option
during core generation.
ECRC Error on the 128-Bit Receive AXI4-Stream Interface
The 7 Series FPGAs Integrated Block for PCI Express core checks the ECRC on incoming
transaction packets, when ECRC checking is enabled in the core. When it detects an ECRC
error in a transaction packet, the core signals this error by simultaneously asserting
m_axis_rx_tuser[0] (rx_ecrc_err) and m_axis_rx_tuser[21:17]
(rx_is_eof[4:0]), as illustrated in Figure 3-53.
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Chapter 3: Designing with the Core
X-Ref Target - Figure 3-53
user_clk_out
m_axis_rx_tdata[127:0]
D0H2H1H0
D4D3D2D1
--D7D6D5
m_axis_rx_tready
m_axis_rx_tvalid
(rx_ecrc_err)m_axis_rx_tuser[0]
(rx_is_sof)m_axis_rx_tuser[14:10]
00000b
10000b
00000b
SOF H0
(rx_is_eof)m_axis_rx_tuser[21:17]
00000b
11011b
00000b
EOF D7
Figure 3-53:
ECRC Error on 128-Bit Receive AXI4-Stream Interface
Packet Base Address Register Hit on the Receive AXI4-Stream Interface
The core decodes incoming Memory and I/O TLP request addresses to determine which
Base Address Register (BAR) in the core Type0 configuration space is being targeted, and
indicates the decoded base address on (rx_bar_hit[7:0]) m_axis_rx_tuser[9:2].
For each received Memory or I/O TLP, a minimum of one and a maximum of two (adjacent)
bits are set to 1. If the received TLP targets a 32-bit Memory or I/O BAR, only one bit is
asserted. If the received TLP targets a 64-bit Memory BAR, two adjacent bits are asserted. If
the core receives a TLP that is not decoded by one of the BARs, then the core drops it
without presenting it, and it automatically generates an Unsupported Request message.
Even if the core is configured for a 64-bit BAR, the system might not always allocate a 64-bit
address, in which case only one rx_bar_hit[7:0] signal is asserted.
Table 3-10 illustrates mapping between rx_bar_hit[7:0] and the BARs, and the
corresponding byte offsets in the core Type0 configuration header.
Table 3-10:
rx_bar_hit to Base Address Register Mapping
rx_bar_hit[x]
m_axis_rx_tuser[x]
BAR
Byte Offset
0
2
0
10h
1
3
1
14h
2
4
2
18h
3
5
3
1Ch
4
6
4
20h
5
7
5
24h
6
8
Expansion ROM BAR
30h
7
9
Reserved
–
For a Memory or I/O TLP Transaction on the receive interface, rx_bar_hit[7:0] is valid
for the entire TLP, starting with the assertion of (rx_is_sof[4])
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Chapter 3: Designing with the Core
m_axis_rx_tuser[14], as shown in Figure 3-54. For straddled data transfer beats,
rx_bar_hit[7:0] corresponds to the new packet (the packet corresponding to
rx_is_sof[4). When receiving non-Memory and non-I/O transactions,
rx_bar_hit[7:0] is undefined.
X-Ref Target - Figure 3-54
user_clk_out
m_axis_rx_tdata[127:0]
H3H2H1H0
D3D2D1D0
D7D6D5D4
D0H2H1H0
TLP1
D4D3D2D1
D8D7D6D5
TLP2
m_axis_rx_tready
m_axis_rx_tvalid
(rx_is_sof[4:0])
m_axis_rx_tuser[14:10]
10000b
00000b
SOF H0
(rx_is_eof[4:0])
m_axis_rx_tuser[21:17]
10000b
00000b
SOF H0
00011b
11111b
00011b
EOF D7
(rx_bar_hit[7:0])
m_axis_rx_tuser[9:2]
0000010b
Figure 3-54:
11111b
EOF D8
0001100b
BAR Target Determination Using rx_bar_hit
The (rx_bar_hit[7:0]) m_axis_rx_tuser[9:2] signal enables received Memory and
I/O transactions to be directed to the appropriate destination apertures within the user
application. By utilizing rx_bar_hit[7:0], application logic can inspect only the lower
order Memory and I/O address bits within the address aperture to simplify decoding logic.
Packet Transfer Discontinue on the Receive AXI4-Stream Interface
The loss of communication with the link partner is signaled by deassertion of
user_lnk_up. When user_lnk_up is deasserted, it effectively acts as a Hot Reset to the
entire core and all TLPs stored inside the core or being presented to the receive interface
are irrecoverably lost. A TLP in progress on the Receive AXI4-Stream interface is presented
to its correct length, according to the Length field in the TLP header. However, the TLP is
corrupt and should be discarded by the user application. Figure 3-55 illustrates packet
transfer discontinue scenario.
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Chapter 3: Designing with the Core
X-Ref Target - Figure 3-55
user_clk_out
user_lnk_up
m_axis_rx_tdata[127:0]
D0H2H1H0
D4D3D2D1
D8D7D6D5
PAD
PAD
original TLP data was lost
m_axis_rx_tready
m_axis_rx_tvalid
(rx_is_sof[4:0])m_axis_rx_tuser[14:10]
10000b
(rx_is_eof[4:0])m_axis_rx_tuser[21:17]
00000b
00000b
Figure 3-55:
11111b
Receive Transaction Discontinue
Transaction Processing on the Receive AXI4-Stream Interface
Transaction processing in the 7 Series FPGAs Integrated Block for PCI Express is fully
compliant with the PCI Express Received TLP handling rules, as specified in the PCI Express
Base Specification, rev. 2.1 [Ref 2].
The core performs checks on received transaction layer packets (TLPs) and passes valid TLPs
to the user application. It handles erroneous TLPs in the manner indicated in Table 3-11 and
Table 3-12. Any errors associated with a TLP that are presented to the user application for
which the core does not check must be signaled by the user application logic using the
cfg_err_* interface.
Table 3-11 and Table 3-12 describe the packet disposition implemented in the core based
on received TLP type and condition of core/TLP error for the Endpoint and Root Port
configurations.
Table 3-11:
TLP Disposition on the Receive AXI4-Stream Interface: Endpoint
TLP Type
Memory Read
Memory Write
Atomic Ops
I/O Read
I/O Write
Condition of Core or TLP Error
BAR Miss
Unsupported Request
Received when in Non-D0 PM
State
Unsupported Request
Neither of the above conditions TLP presented to user application
Received by a non-Legacy
PCI Express Endpoint
BAR Miss
Memory Read Locked
Core Response to TLP
Legacy
Endpoint
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Unsupported Request
Received when in
Unsupported Request
Non-D0 PM State
Neither of the
above conditions
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Table 3-11:
TLP Disposition on the Receive AXI4-Stream Interface: Endpoint (Cont’d)
TLP Type
Configuration Read/Write Type 0
Configuration Read/Write Type 1
Completion
Completion Locked
Condition of Core or TLP Error
Core Response to TLP
Internal Config Space
TLP consumed by the core, to read/write
internal Configuration Space and a CplD/
Cpl is generated
User-Defined Config Space
TLP presented to user application
Received by an Endpoint
Unsupported Request
Requester ID Miss
Unexpected Completion
Received when in Non-D0 PM
State
Unexpected Completion
Neither of the above conditions TLP presented to user application
Set Slot Power Limit
Received by an Endpoint
TLP consumed by the core and used to
program the Captured Slot Power Limit
Scale/Value fields of the Device
Capabilities Register
PM_PME
PME_TO_Ack
Received by an Endpoint
Unsupported Request
PM_Active_State_NAK
PME_Turn_Off
Received by an Endpoint
TLP consumed by the core and used to
control Power Management
Received by a non-Legacy
Endpoint
Ignored
Received by a Legacy Endpoint
TLP presented to user application (1)
INTX
Received by an Endpoint
Fatal Error
Error_Fatal
Error Non-Fatal
Error Correctable
Received by an Endpoint
Unsupported Request
Messages Unlock
Vendor Defined Type 0
Received by an Endpoint
Vendor Defined Type 1
TLP presented to user application(1)
Hot Plug Messages
TLP dropped by the core
Received by an Endpoint
Notes:
1. The TLP is indicated on the cfg_msg* interface and also appears on the m_axis_rx_* interface.
Table 3-12:
TLP Disposition on the Receive AXI4-Stream Interface: Root Port
TLP Type
Condition of Core or TLP
Error
Core Response to TLP
Memory Read
Memory Write
Atomic Ops
I/O Read
I/O Write
BAR Miss
No BAR Filtering in Root Port configuration:
TLP presented to user application
Received when in Non-D0 PM
State
Unsupported Request
Neither of the above
conditions
TLP presented to user application
Memory Read Locked
Received by a Root Port
TLP presented to user application
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Table 3-12:
TLP Disposition on the Receive AXI4-Stream Interface: Root Port (Cont’d)
TLP Type
Condition of Core or TLP
Error
Core Response to TLP
Configuration Read / Write Type 0 Received by a Root Port
Unsupported Request
Configuration Read / Write Type 1 Received by a Root Port
Unsupported Request
Completion
Completion Locked
Received by a Root Port
TLP presented to user application
Set Slot Power Limit
Received by a Root Port
Unsupported Request
PM_PME
PME_TO_Ack
Received by a Root Port
TLP presented to user application (1)
PM_Active_State_NAK
Received by a Root Port
Unsupported Request
PME_Turn_Off
Received by a Root Port
Fatal Error
Received by a Root Port
Fatal Error
Received by a Root Port
TLP presented to user application (1)
Received by a Root Port
TLP presented to user application (1)
Vendor Defined Type 0
Received by a Root Port
Vendor Defined Type 1
TLP presented to user application (1)
Hot Plug Messages
TLP dropped by the core
Unlock
Messages INTX
Error_Fatal
Error Non-Fatal
Error Correctable
Received by a Root Port
Notes:
1. The TLP is indicated on the cfg_msg* interface and also appears on the m_axis_rx* interface only if enabled in the Vivado
Integrated Design Environment (IDE).
Atomic Operations
The 7 Series FPGAs Integrated Block for PCI Express supports both sending and receiving
Atomic operations (Atomic Ops) as defined in the PCI Express Base Specification v2.1. The
specification defines three TLP types that allow advanced synchronization mechanisms
amongst multiple producers and/or consumers. The integrated block treats Atomic Ops
TLPs as Non-Posted Memory Transactions. The three TLP types are:
•
FetchAdd
•
Swap
•
CAS (Compare And Set)
Applications that request Atomic Ops must create the TLP in the user application and send
through the transmit AXI4-Stream interface. Applications that respond (complete) to
Atomic Ops must receive the TLP from the receive AXI4-Stream interface, create the
appropriate completion TLP in the user application, and send the resulting completion
through the transmit AXI4-Stream interface.
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Chapter 3: Designing with the Core
Core Buffering and Flow Control
Maximum Payload Size
TLP size is restricted by the capabilities of both link partners. After the link is trained, the
root complex sets the MAX_PAYLOAD_SIZE value in the Device Control register. This value is
equal to or less than the value advertised by the Device Capability register of the core. The
advertised value in the Device Capability register of the integrated block core is either 128,
256, 512, or 1024 bytes, depending on the setting in the Vivado IDE (1024 is not supported
for the 8-lane, 5.0 Gb/s 128-bit core). For more information about these registers, see
section 7.8 of the PCI Express Base Specification [Ref 2]. The value of the Device Control
register of the core is provided to the user application on the cfg_dcommand[15:0]
output. See Designing with Configuration Space Registers and Configuration Interface,
page 105 for information about this output.
Transmit Buffers
The Integrated Block for PCI Express transmit AXI4-Stream interface provides tx_buf_av, an
instantaneous indication of the number of Max_Payload_Size buffers available for use in the
transmit buffer pool. Table 3-13 defines the number of transmit buffers available and
maximum supported payload size for a specific core.
Table 3-13:
Transmit Buffers Available
Performance Level(1)
Capability Max
Payload Size
(Bytes)
Good (Minimize Block RAM Usage)
High (Maximize Performance)
128
26
32
256
14
29
512
15
30
15
31
1024
(2)
Notes:
1. Performance level is set through a Vivado IDE selection.
2. 1024 is not supported for the 8-lane, 5.0 Gb/s, 128-bit core.
Each buffer can hold one maximum sized TLP. A maximum sized TLP is a TLP with a
4-DWORD header plus a data payload equal to the Max_Payload_Size of the core (as
defined in the Device Capability register) plus a TLP Digest. After the link is trained, the root
complex sets the Max_Payload_Size value in the Device Control register. This value is equal
to or less than the value advertised by the Device Capability register of the core. For more
information about these registers, see section 7.8 of the PCI Express Base Specification. A
TLP is held in the transmit buffer of the core until the link partner acknowledges receipt of
the packet, at which time the buffer is released and a new TLP can be loaded into it by the
user application.
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For example, if the Capability Max Payload Size selected for the Endpoint core is 256 bytes,
and the performance level selected is high, there are 29 total transmit buffers. Each of these
buffers can hold at a maximum one 64-bit Memory Write Request (4-DWORD header) plus
256 bytes of data (64 DWORDs) plus TLP Digest (one DWORD) for a total of 69 DWORDs.
This example assumes the root complex sets the MAX_PAYLOAD_SIZE register of the Device
Control register to 256 bytes, which is the maximum capability advertised by this core. For
this reason, at any given time, this core could have 29 of these 69 DWORD TLPs waiting for
transmittal. There is no sharing of buffers among multiple TLPs, so even if user is sending
smaller TLPs such as 32-bit Memory Read request with no TLP Digest totaling three
DWORDs only per TLP, each transmit buffer still holds only one TLP at any time.
The internal transmit buffers are shared between the user application and the configuration
management module (CMM) of the core. Because of this, the tx_buf_av bus can fluctuate
even if the user application is not transmitting packets. The CMM generates completion
TLPs in response to configuration reads or writes, interrupt TLPs at the request of the user
application, and message TLPs when needed.
The Transmit Buffers Available indication enables the user application to completely utilize
the PCI transaction ordering feature of the core transmitter. The transaction ordering rules
allow for Posted and Completion TLPs to bypass Non-Posted TLPs. See section 2.4 of the
PCI Express Base Specification [Ref 2] for more information about ordering rules.
The core supports the transaction ordering rules and promotes Posted and Completion
packets ahead of blocked Non-Posted TLPs. Non-Posted TLPs can become blocked if the
link partner is in a state where it momentarily has no Non-Posted receive buffers available,
which it advertises through Flow Control updates. In this case, the core promotes
Completion and Posted TLPs ahead of these blocked Non-Posted TLPs. However, this can
only occur if the Completion or Posted TLP has been loaded into the core by the user
application. By monitoring the tx_buf_av bus, the user application can ensure there is at
least one free buffer available for any Completion or Posted TLP. Promotion of Completion
and Posted TLPs only occurs when Non-Posted TLPs are blocked; otherwise packets are sent
on the link in the order they are received from the user application.
Receiver Flow Control Credits Available
The core provides the user application information about the state of the receiver buffer
pool queues. This information represents the current space available for the Posted,
Non-Posted, and Completion queues.
One Header Credit is equal to either a 3- or 4-DWORD TLP Header and one Data Credit is
equal to 16 bytes of payload data. Table 3-14 provides values on credits available
immediately after user_lnk_up assertion but before the reception of any TLP. If space
available for any of the above categories is exhausted, the corresponding credit available
signals indicate a value of zero. Credits available return to initial values after the receiver has
drained all TLPs.
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Table 3-14:
Transaction Receiver Credits Available Initial Values
Credit Category
Performance
Level
Non-Posted Header
Capability Maximum Payload Size
128 Byte
256 Byte
Good
Good
12
High
Posted Header
Good
32
High
Posted Data
Completion Header
Good
77
77
154
308
High
154
154
308
616
Good
36
High
Completion Data
1024 Byte
12
High
Non-Posted Data
512 Byte
Good
77
77
154
308
High
154
154
308
616
The user application can use the fc_ph[7:0], fc_pd[11:0], fc_nph[7:0],
fc_npd[11:0], fc_cplh[7:0], fc_cpld[11:0], and fc_sel[2:0] signals to
efficiently utilize and manage receiver buffer space available in the core and the core
application. For additional information, see Flow Control Credit Information.
Endpoint cores have a unique requirement where the user application must use advanced
methods to prevent buffer overflows when requesting Non-Posted Read Requests from an
upstream component. According to the specification, a PCI Express Endpoint is required to
advertise infinite storage credits for Completion Transactions in its receivers. This means
that Endpoints must internally manage Memory Read Requests transmitted upstream and
not overflow the receiver when the corresponding Completions are received. The user
application transmit logic must use Completion credit information presented to modulate
the rate and size of Memory Read requests, to stay within the instantaneous Completion
space available in the core receiver. For additional information, see Appendix C, Managing
Receive-Buffer Space for Inbound Completions.
Flow Control Credit Information
The integrated block provides the user application with information about the state of the
Transaction Layer transmit and receive buffer credit pools. This information represents the
current space available, as well as the credit “limit” and “consumed” information for the
Posted, Non-Posted, and Completion pools.
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Chapter 3: Designing with the Core
Table 2-7, page 15 defines the Flow Control Credit signals. Credit status information is
presented on these signals:
•
fc_ph[7:0]
•
fc_pd[11:0]
•
fc_nph[7:0]
•
fc_npd[11:0]
•
fc_cplh[7:0]
•
fc_cpld[11:0]
Collectively, these signals are referred to as fc_*.
The fc_* signals provide information about each of the six credit pools defined in the
PCI Express Base Specification: Header and Data Credits for Each of Posted, Non-Posted, and
Completion.
Six different types of flow control information can be read by the user application. The
fc_sel[2:0] input selects the type of flow control information represented by the fc_*
outputs. The Flow Control Information Types are shown in Table 3-15.
Table 3-15:
Flow Control Information Types
fc_sel[2:0]
Flow Control Information Type
000
Receive Credits Available Space
001
Receive Credits Limit
010
Receive Credits Consumed
011
Reserved
100
Transmit Credits Available Space
101
Transmit Credit Limit
110
Transmit Credits Consumed
111
Reserved
The fc_sel[2:0] input can be changed on every clock cycle to indicate a different Flow
Control Information Type. There is a two clock-cycle delay between the value of
fc_sel[2:0] changing and the corresponding Flow Control Information Type being
presented on the fc_* outputs for both 64-bit and 128-bit interface. Figure 3-56 illustrates
the timing of the Flow Control Credits signals.
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Chapter 3: Designing with the Core
X-Ref Target - Figure 3-56
user_clk_out
fc_sel[2:0]
000b
001b
fc_*
Figure 3-56:
110b
RX Avail
RX Limit
TX Consumed
Flow Control Credits for the 64-Bit and 128-Bit Interfaces
The output values of the fc_* signals represent credit values as defined in the PCI Express
Base Specification [Ref 2]. One Header Credit is equal to either a 3- or 4-DWORD TLP Header
and one Data Credit is equal to 16 bytes of payload data. Initial credit information is
available immediately after user_lnk_up assertion, but before the reception of any TLP.
Table 3-16 defines the possible values presented on the fc_* signals. Initial credit
information varies depending on the size of the receive buffers within the integrated block
and the Link Partner.
Table 3-16:
fc_* Value Definition
Header Credit Value
Data Credit Value
00 – 7F
000 – 7FF
FF-80
FFF-800
7F
7FF
Meaning
User credits
Negative credits available(1)
Infinite credits available (1)
Notes:
1. Only Transmit Credits Available Space indicate Negative or Infinite credits available.
Receive Credit Flow Control Information
Receive Credit Flow Control Information can be obtained by setting fc_sel[2:0] to
000b, 001b, or 010b. The Receive Credit Flow Control information indicates the current
status of the receive buffers within the integrated block.
•
Receive Credits Available Space: fc_sel[2:0] = 000b
Receive Credits Available Space shows the credit space available in the integrated block
Transaction Layer local receive buffers for each credit pool. If space available for any of
the credit pools is exhausted, the corresponding fc_* signal indicates a value of zero.
Receive Credits Available Space returns to its initial values after the user application has
drained all TLPs from the integrated block.
In the case where infinite credits is advertised to the Link Partner for a specific Credit
pool, such as Completion Credits for Endpoints, the user application should use this
value along with the methods described in Appendix C, Managing Receive-Buffer Space
for Inbound Completions to avoid completion buffer overflow.
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•
Receive Credits Limit: fc_sel[2:0] = 001b
Receive Credits Limit shows the credits granted to the link partner. The fc_* values are
initialized with the values advertised by the integrated block during Flow Control
initialization and are updated as a cumulative count as TLPs are read out of the
Transaction Layer receive buffers through the AXI4-Stream interface. This value is
referred to as CREDITS_ALLOCATED within the PCI Express Base Specification.
In the case where infinite credits have been advertised for a specific credit pool, the
Receive Buffer Credits Limit for that pool always indicates zero credits.
•
Receive Credits Consumed: fc_sel[2:0] = 010b
Receive Buffer Credits Consumed shows the credits consumed by the link partner (and
received by the integrated block). The initial fc_* values are always zero and are
updated as a cumulative count, as packets are received by the Transaction Layers receive
buffers. This value is referred to as CREDITS_RECEIVED in the PCI Express Base
Specification.
Transmit Credit Flow Control Information
Transmit Credit Flow Control Information can be obtained by setting fc_sel[2:0] to
100b, 101b, or 110b. The Transmit Credit Flow Control information indicates the current
status of the receive buffers within the Link Partner.
•
Transmit Credits Available Space: fc_sel[2:0] = 100b
Transmit Credits Available Space indicates the available credit space within the receive
buffers of the Link Partner for each credit pool. If space available for any of the credit
pools is exhausted, the corresponding fc_* signal indicates a value of zero or negative.
Transmit Credits Available Space returns to its initial values after the integrated block
has successfully sent all TLPs to the Link Partner.
If the value is negative, more header or data has been written into the local transmit
buffers of the integrated block than the Link Partner can currently consume. Because the
block does not allow posted packets to pass completions, a posted packet that is written
is not transmitted if there is a completion ahead of it waiting for credits (as indicated by
a zero or negative value). Similarly, a completion that is written is not transmitted if a
posted packet is ahead of it waiting for credits. The user application can monitor the
Transmit Credits Available Space to ensure that these temporary blocking conditions do
not occur, and that the bandwidth of the PCI Express Link is fully utilized by only writing
packets to the integrated block that have sufficient space within the Receive buffer of
the Link Partner. Non-Posted packets can always be bypassed within the integrated
block; so, any Posted or Completion packet written passes Non-Posted packets waiting
for credits.
The Link Partner can advertise infinite credits for one or more of the three traffic types.
Set the Header and Data credit outputs to their maximum value, as indicated in
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Chapter 3: Designing with the Core
Table 3-16, to indicate infinite credits.
•
Transmit Credits Limit: fc_sel[2:0] = 101b
Transmit Credits Limit shows the receive buffer limits of the Link Partner for each credit
pool. The fc_* values are initialized with the values advertised by the Link Partner
during Flow Control initialization and are updated as a cumulative count as Flow Control
updates are received from the Link Partner. This value is referred to as CREDITS_LIMIT in
the PCI Express Base Specification [Ref 2].
In the case where infinite credits have been advertised for a specific Credit pool, the
Transmit Buffer Credits Limit always indicates zero credits for that pool.
•
Transmit Credits Consumed: fc_sel[2:0] = 110b
Transmit Credits Consumed show the credits consumed of the Receive Buffer of the Link
Partner by the integrated block. The initial value is always zero and is updated as a
cumulative count, as packets are transmitted to the Link Partner. This value is referred to
as CREDITS_CONSUMED in the PCI Express Base Specification.
Designing with the Physical Layer Control and Status Interface
Physical Layer Control and Status enables the user application to change link width and
speed in response to data throughput and power requirements.
Design Considerations for a Directed Link Change
These points should be considered during a Directed Link Change:
•
Link change operation must be initiated only when user_lnk_up is asserted and the
core is in the L0 state, as indicated by the pl_ltssm_state[5:0] signal.
•
Link Width Change should not be used when Lane Reversal is enabled.
•
Target Link Width of a Link Width Change operation must be equal to or less than the
width indicated by pl_initial_link_width output.
•
When pl_link_upcfg_cap is set to 1b, the PCI Express link is Upconfigure capable.
This allows the link width to be varied between the Initial Negotiated Link Width and
any smaller link width supported by both the Port and link partner (this is for link
reliability or application reasons).
•
If a link is not Upconfigure capable, the Negotiated link width can only be varied to a
width less than the Negotiated Link Width that is supported by both the link partner
and device.
•
Before initiating a link speed change from 2.5 Gb/s to 5.0 Gb/s, the user application
must ensure that the link is 5.0 Gb/s (Gen2) capable (that is, pl_link_gen2_cap is
1b) and the Link Partner is also Gen2 capable (pl_link_partner_gen2_capable is
1b).
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Chapter 3: Designing with the Core
•
A link width change that benefits the application must be initiated only when
cfg_lcommand[9] (the Hardware Autonomous Width Disable bit) is 0b. In addition,
for both link speed and/or width change driven by application need,
pl_directed_link_auton must be driven (1b). To restore the link width and speed
to the original (higher) width and speed, set pl_link_upcfg_cap to 1b.
•
If the user application directs the link to a width not supported by the link partner, the
resulting link width is the next narrower mutually supported link width. For example, an
8-lane link is directed to a 4-lane operation, but the link partner supports only 1-lane
train down operations. So, this would result in a 1-lane operation.
•
The Endpoint should initiate directed link change only when the device is in D0 power
state (cfg_pmcsr_powerstate[1:0] = 00b).
•
A retrain should not be initiated using directed link change pins (Root or Endpoint) or
by setting the retrain bit (Root only), if the cfg_pcie_link_state = 101b
(transitioning to/from PPM L1) or 110b (transitioning to PPM L2/L3 Ready).
•
To ease timing closure, it is permitted to check for the conditions specified above to be
all simultaneously TRUE up to 16 user clock cycles before initiating a Directed Link
Change. These conditions are:
°
user_lnk_up == 1'b1
°
pl_ltssm_state[5:0] == 6'h16
°
cfg_lcommand[9] == 1'b0
°
cfg_pmcsr_powerstate[1:0] == 2'b00
°
cfg_pcie_link_state[2:0] != either 3'b101 or 3'b110
Directed Link Width Change
Figure 3-57 shows the directed link width change process that must be implemented by the
user application. Here target_link_width[1:0] is the application-driven new link
width request.
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Chapter 3: Designing with the Core
X-Ref Target - Figure 3-57
No
usr_lnk_up = 1b
and
pl_ltssm_state[5:0] = L0
Yes
Assign target _link_width[1:0]
No
target _link_width[1:0] != pl_sel_lnk_width[1:0]
Yes
Yes
Yes
No
pl_link_upcfg_cap == 1b
target _link_width[1:0] <=
(pl_initial_link_width[2:0] -1)
No
No
target _link_width[1:0] <
pl_sel_lnk_width[1:0]
Yes
Unsupported
Operation
pl_directed _lnk_width[1:0] = target_link_width[1:0]
pl_directed _link_change[1:0] = 01b
((pl_directed_change_done == 1b) ||
(user_lnk_up == 0b))
No
Yes
pl_directed _link_change[1:0] = 00b
Change Complete
Figure 3-57:
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Chapter 3: Designing with the Core
Directed Link Speed Change
Figure 3-58 shows the directed link speed change process that must be implemented by the
user application. Here target_link_speed is the application-driven new link speed
request.
Note: A link speed change should not be initiated on a Root Port by driving the
pl_directed_link_change pin to 10 or 11 unless the attribute RP_AUTO_SPD = 11.
X-Ref Target - Figure 3-58
No
user_lnk_up = 1b
and
pl_ltssm_state[5:0] = L0
Yes
Assign target _link_speed
No
target _link_speed != pl_sel_link_rate
Yes
pl_directed_lnk_speed = target_link_speed
pl_directed_link_change [1:0] = 10b
((pl_directed_change_done == 1b) ||
(user_lnk_up == 0b))
No
Yes
pl_directed_link_change [1:0] = 00b
Change Complete
Figure 3-58:
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Chapter 3: Designing with the Core
Directed Link Width and Speed Change
Figure 3-59 shows the directed link width and speed change process that must be
implemented by the user application. Here target_link_width[1:0] is the application-driven
new link width request, and target_link_speed is the application-driven new link speed
request.
Note: A link speed change should not be initiated on a Root Port by driving the
pl_directed_link_change pin to 10 or 11 unless the attribute RP_AUTO_SPD = 11.
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Chapter 3: Designing with the Core
X-Ref Target - Figure 3-59
No
user_lnk_up = 1b
and
pl_ltssm_state[5:0] = L0
Yes
Assign target _link_width[1:0]
Assign target _link_speed
No
(target_link_width[1:0] != pl_sel_lnk_width[1:0])
&&
(target _link_speed != pl_sel_lnk_rate)
Yes
Yes
Yes
No
pl_link_upcfg_capable == 1b
target _link_width[1:0] <=
(pl_initial_link_width[2:0] -1)
No
No
target _link_width[1:0] <
pl_sel_lnk_width[1:0]
Yes
Unsupported
Operation
pl_directed _lnk_width[1:0] = target_link_width[1:0]
pl_directed _lnk_speed = target_link_speed
pl_directed _link_change[1:0] = 11b
((pl_directed_change_done == 1b) ||
(user_lnk_up == 0b))
No
Yes
pl_directed _link_change[1:0] = 00b
Change Complete
Figure 3-59:
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Chapter 3: Designing with the Core
Designing with Configuration Space Registers and Configuration
Interface
This section describes the use of the Configuration interface for accessing the PCI Express
Configuration Space Type 0 or Type 1 registers that are part of the Integrated Block core.
The Configuration interface includes a read/write Configuration Port for accessing the
registers. In addition, some commonly used registers are mapped directly on the
Configuration interface for convenience.
Registers Mapped Directly onto the Configuration Interface
The Integrated Block core provides direct access to select command and status registers in
its Configuration Space. For Endpoints, the values in these registers are typically modified
by Configuration Writes received from the Root Complex; however, the user application can
also modify these values using the Configuration Port. In the Root Port configuration, the
Configuration Port must always be used to modify these values. Table 3-17 defines the
command and status registers mapped to the configuration port.
Table 3-17:
Command and Status Registers Mapped to the Configuration Port
Port Name
Direction
Description
cfg_bus_number[7:0]
Output
Bus Number: Default value after reset is 00h. Refreshed
whenever a Type 0 Configuration Write packet is
received.
cfg_device_number[4:0]
Output
Device Number: Default value after reset is 00000b.
Refreshed whenever a Type 0 Configuration Write packet
is received.
cfg_function_number[2:0]
Output
Function Number: Function number of the core,
hardwired to 000b.
cfg_status[15:0]
Output
Status Register: Status register from the Configuration
Space Header. Not supported.
cfg_command[15:0]
Output
Command Register: Command register from the
Configuration Space Header.
cfg_dstatus[15:0]
Output
Device Status Register: Device status register from the
PCI Express Capability Structure.
cfg_dcommand[15:0]
Output
Device Command Register: Device control register from
the PCI Express Capability Structure.
cfg_dcommand2[15:0]
Output
Device Command 2 Register: Device control 2 register
from the PCI Express Capability Structure.
cfg_lstatus[15:0]
Output
Link Status Register: Link status register from the PCI
Express Capability Structure.
cfg_lcommand[15:0]
Output
Link Command Register: Link control register from the
PCI Express Capability Structure.
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Chapter 3: Designing with the Core
Device Control and Status Register Definitions
cfg_bus_number[7:0], cfg_device_number[4:0], cfg_function_number[2:0]
Together, these three values comprise the core ID, which the core captures from the
corresponding fields of inbound Type 0 Configuration Write accesses. The user application
is responsible for using this core ID as the Requestor ID on any requests it originates, and
using it as the Completer ID on any Completion response it sends. This core supports only
one function; for this reason, the function number is hardwired to 000b.
cfg_status[15:0]
This output bus is not supported. This information can be retrieved by Read access of the
Configuration Space in the 7 Series FPGAs Integrated Block for PCI Express using the
Configuration Port.
cfg_command[15:0]
This bus reflects the value stored in the Command register in the PCI Configuration Space
Header. Table 3-18 provides the definitions for each bit in this bus. See the PCI Express Base
Specification [Ref 2] for detailed information.
Table 3-18:
Bit Mapping on Header Command Register
Bit
Name
cfg_command[15:11]
Reserved
cfg_command[10]
Interrupt Disable
cfg_command[9]
Fast Back-to-Back Transactions Enable (hardwired to 0)
cfg_command[8]
SERR Enable
cfg_command[7]
IDSEL Stepping/Wait Cycle Control (hardwired to 0)
cfg_command[6]
Parity Error Enable - Not Supported
cfg_command[5]
VGA Palette Snoop (hardwired to 0)
cfg_command[4]
Memory Write and Invalidate (hardwired to 0)
cfg_command[3]
Special Cycle Enable (hardwired to 0)
cfg_command[2]
Bus Master Enable
cfg_command[1]
Memory Address Space Decoder Enable
cfg_command[0]
I/O Address Space Decoder Enable
The user application must monitor the Bus Master Enable bit (cfg_command[2]) and refrain
from transmitting requests while this bit is not set. This requirement applies only to
requests; completions can be transmitted regardless of this bit.
The Memory Address Space Decoder Enable bit (cfg_command[1]) or the I/O Address Space
Decoder Enable bit (cfg_command[0]) must be set to receive Memory or I/O requests. These
bits are set by an incoming Configuration Write request from the system host.
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Chapter 3: Designing with the Core
cfg_dstatus[15:0]
This bus reflects the value stored in the Device Status register of the PCI Express Capabilities
Structure. Table 3-19 defines each bit in the cfg_dstatus bus. See the PCI Express Base
Specification [Ref 2] for detailed information.
Table 3-19:
Bit Mapping on PCI Express Device Status Register
Bit
Name
cfg_dstatus[15:6]
Reserved
cfg_dstatus[5]
Transaction Pending
cfg_dstatus[4]
AUX Power Detected (hardwired to 0)
cfg_dstatus[3]
Unsupported Request Detected
cfg_dstatus[2]
Fatal Error Detected
cfg_dstatus[1]
Non-Fatal Error Detected
cfg_dstatus[0]
Correctable Error Detected
cfg_dcommand[15:0]
This bus reflects the value stored in the Device Control register of the PCI Express
Capabilities Structure. Table 3-20 defines each bit in the cfg_dcommand bus. See the
PCI Express Base Specification for detailed information.
Table 3-20:
Bit Mapping of PCI Express Device Control Register
Bit
Name
cfg_dcommand[15]
Reserved
cfg_dcommand[14:12]
Max_Read_Request_Size
cfg_dcommand[11]
Enable No Snoop
cfg_dcommand[10]
Auxiliary Power PM Enable
cfg_dcommand[9]
Phantom Functions Enable
cfg_dcommand[8]
Extended Tag Field Enable
cfg_dcommand[7:5]
Max_Payload_Size
cfg_dcommand[4]
Enable Relaxed Ordering
cfg_dcommand[3]
Unsupported Request Reporting Enable
cfg_dcommand[2]
Fatal Error Reporting Enable
cfg_dcommand[1]
Non-Fatal Error Reporting Enable
cfg_dcommand[0]
Correctable Error Reporting Enable
cfg_lstatus[15:0]
This bus reflects the value stored in the Link Status register in the PCI Express Capabilities
Structure. Table 3-21 defines each bit in the cfg_lstatus bus. See the PCI Express Base
Specification for details.
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Chapter 3: Designing with the Core
Table 3-21:
Bit Mapping of PCI Express Link Status Register
Bit
Name
cfg_lstatus[15]
Link Autonomous Bandwidth Status
cfg_lstatus[14]
Link Bandwidth Management Status
cfg_lstatus[13]
Data Link Layer Link Active
cfg_lstatus[12]
Slot Clock Configuration
cfg_lstatus[11]
Link Training
cfg_lstatus[10]
Reserved
cfg_lstatus[9:4]
Negotiated Link Width
cfg_lstatus[3:0]
Current Link Speed
cfg_lcommand[15:0]
This bus reflects the value stored in the Link Control register of the PCI Express Capabilities
Structure. Table 3-22 provides the definition of each bit in cfg_lcommand bus. See the PCI
Express Base Specification, rev. 2.1 for more details.
Table 3-22:
Bit Mapping of PCI Express Link Control Register
Bit
Name
cfg_lcommand[15:12]
Reserved
cfg_lcommand[11]
Link Autonomous Bandwidth Interrupt Enable
cfg_lcommand[10]
Link Bandwidth Management Interrupt Enable
cfg_lcommand[9]
Hardware Autonomous Width Disable
cfg_lcommand[8]
Enable Clock Power Management
cfg_lcommand[7]
Extended Synch
cfg_lcommand[6]
Common Clock Configuration
cfg_lcommand[5](1)
Retrain Link (Reserved for an Endpoint device)
cfg_lcommand[4]
Link Disable
cfg_lcommand[3]
Read Completion Boundary
cfg_lcommand[2]
Reserved
cfg_lcommand[1:0]
Active State Link PM Control
Notes:
1. During L1 negotiation, do not trigger a link retrain by writing a 1 to cfg_lcommand[5]. L1 negotiation can be
observed by monitoring the cfg_pcie_link_state port.
cfg_dcommand2[15:0]
This bus reflects the value stored in the Device Control 2 register of the PCI Express
Capabilities Structure. Table 3-23 defines each bit in the cfg_dcommand bus. See the
PCI Express Base Specification [Ref 2] for detailed information.
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Chapter 3: Designing with the Core
Table 3-23:
Bit Mapping of PCI Express Device Control 2 Register
Bit
Name
cfg_dcommand2[15:5]
Reserved
cfg_dcommand2[4]
Completion Timeout Disable
cfg_dcommand2[3:0]
Completion Timeout Value
Core Response to Command Register Settings
Table 3-24 and Table 3-25 illustrate the behavior of the core based on the Command
Register settings when configured as either an Endpoint or a Root Port.
Table 3-24:
Command Register (0x004): Endpoint
Bit
Name
Attr
Endpoint Core Behavior
0
I/O Space Enable
RW
The Endpoint does not permit a BAR hit on I/O space unless
this is enabled.
1
Memory Space Enable
RW
The Endpoint does not permit a BAR hit on Memory space
unless this is enabled.
2
Bus Master Enable
RW
The Endpoint does not enforce this; user could send a TLP
through the AXI4-Stream interface.
Reserved
RO
Wired to 0. Not applicable to PCI Express.
6
Parity Error Response
RW
Enables Master Data Parity Error (Status[8]) to be set.
7
Reserved
RO
Wired to 0. Not applicable to PCI Express.
8
SERR# Enable
RW
Can enable Error NonFatal / Error Fatal Message generation,
and enables Status[14] (“Signaled System Error”).
9
Reserved
RO
Wired to 0. Not applicable to PCI Express.
10
Interrupt Disable
RW
If set to 1, the cfg_interrupt* interface is unable to cause INTx
messages to be sent.
Reserved
RO
Wired to 0. Not applicable to PCI Express.
5:3
15:11
Table 3-25:
Bit
Command Register (0x004): Root Port
Name
Attr
Root Port Core behavior
0
I/O Space Enable
RW
The Root Port ignores this setting. If disabled, it still accepts
I/O TLP from the user side and passes downstream. The user
application logic must enforce not sending I/O TLPs
downstream if this is unset.
1
Memory Space Enable
RW
The Root Port ignores this setting. If disabled, it still accepts
Mem TLPs from the user side and passes downstream. The
user application logic must enforce not sending Mem TLPs
downstream if this is unset.
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Table 3-25:
Command Register (0x004): Root Port (Cont’d)
Bit
Attr
Root Port Core behavior
Bus Master Enable
RW
When set to 0, the Root Port responds to target transactions
such as an Upstream Mem or I/O TLPs as a UR (that is, the UR
bit is set if enabled or a Cpl w/ UR packet is sent if the TLP
was Non-Posted).
When set to 1, all target transactions are passed to the user.
Reserved
RO
Wired to 0. Not applicable to PCI Express.
6
Parity Error Response
RW
Enables Master Data Parity Error (Status[8]) to be set.
7
Reserved
RO
Wired to 0. Not applicable to PCI Express.
8
SERR# Enable
RW
If enabled, Error Fatal/Error Non-Fatal Messages can be
forwarded from the AXI4-Stream interface or cfg_err*, or
internally generated. The Root Port does not enforce the
requirement that Error Fatal/Error Non-Fatal Messages
received on the link not be forwarded if this bit is unset;
instead, the user logic must do that.
Note: Error conditions detected internal to the Root Port are
indicated on cfg_msg* interface.
9
Reserved
RO
Wired to 0. Not applicable to PCI Express.
10
Interrupt Disable
RW
Not applicable to Root Port.
Reserved
RO
Wired to 0. Not applicable to PCI Express.
2
5:3
15:11
Name
Status Register Response to Error Conditions
Table 3-26 throughTable 3-28 illustrate the conditions that cause the Status Register bits to
be set in the core when configured as either an Endpoint or a Root Port.
Table 3-26:
Status Register (0x006): Endpoint
Bit
Name
Attr
Cause in an Endpoint
Reserved
RO
Wired to 0. Not applicable to PCI Express.
3
Interrupt Status
RO
• Set when interrupt signaled by user.
• Clears when interrupt is cleared by the Interrupt
handler.
4
Capabilities List
RO
Wired to 1.
Reserved
RO
Wired to 0. Not applicable to PCI Express.
2:0
7:5
8
10:9
Master Data Parity Error
Reserved
RW1C
RO
Set if Parity Error Response is set and a Poisoned Cpl TLP
is received on the link, or a Poisoned Write TLP is sent.
Wired to 0. Not applicable to PCI Express.
11
Signaled Target Abort
RW1C
Set if a Completion with status Completer Abort is sent
upstream by the user application through the
cfg_err* interface.
12
Received Target Abort
RW1C
Set if a Completion with status Completer Abort is
received.
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Table 3-26:
Status Register (0x006): Endpoint (Cont’d)
Bit
Name
Attr
Cause in an Endpoint
13
Received Master Abort
RW1C
Set if a Completion with status Unsupported Request is
received.
14
Signaled System Error
RW1C
Set if an Error Non-Fatal / Error Fatal Message is sent,
and SERR# Enable (Command[8]) is set.
15
Detected Parity Error
RW1C
Set if a Poisoned TLP is received on the link.
Table 3-27:
Status Register (0x006): Root Port
Bit
Name
Attr
Cause in a Root Port
Reserved
RO
Wired to 0. Not applicable to PCI Express.
3
Interrupt Status
RO
Has no function in the Root Port.
4
Capabilities List
RO
Wired to 1.
Reserved
RO
Wired to 0. Not applicable to PCI Express.
2:0
7:5
8
10:9
Master Data Parity Error
Reserved
RW1C
RO
Set if Parity Error Response is set and a Poisoned
Completion TLP is received on the link.
Wired to 0. Not applicable to PCI Express.
11
Signaled Target Abort
RW1C
Never set by the Root Port
12
Received Target Abort
RW1C
Never set by the Root Port
13
Received Master Abort
RW1C
Never set by the Root Port
14
Signaled System Error
RW1C
Set if the Root Port:
• Receives an Error Non-Fatal / Error Fatal Message and
both SERR# Enable and Secondary SERR# enable are
set.
• Indicates on the cfg_msg* interface that a Error Fatal
/ Error Non-Fatal Message should be generated
upstream and SERR# enable is set.
15
Detected Parity Error
RW1C
Set if a Poisoned TLP is transmitted downstream.
Table 3-28:
Secondary Status Register (0x01E): Root Port
Bit
7:0
8
10:9
Name
Attr
Reserved
Secondary Master Data Parity Error
Reserved
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Cause in a Root Port
RO
Wired to 0. Not applicable to PCI Express.
RW1C
Set when the Root Port:
Receives a Poisoned Completion TLP, and
Secondary Parity Error Response==1
Transmits a Poisoned Write TLP, and
Secondary Parity Error Response==1
RO
Wired to 0. Not applicable to PCI Express.
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Table 3-28:
Bit
Secondary Status Register (0x01E): Root Port
Name
Attr
Cause in a Root Port
11
Secondary Signaled Target Abort
RW1C
Set when user applicable indicates a
Completer-Abort through
cfg_err_cpl_abort.
12
Secondary Received Target Abort
RW1C
Set when the Root Port receives a Completion
TLP with status Completer-Abort.
13
Secondary Received Master Abort
RW1C
Set when the Root Port receives a Completion
TLP with status Unsupported Request
14
Secondary Received System Error
RW1C
Set when the Root Port receives an Error Fatal/
Error Non-Fatal Message.
15
Secondary Detected Parity Error
RW1C
Set when the Root Port receives a Poisoned
TLP.
Accessing Registers through the Configuration Port
Configuration registers that are not directly mapped to the user interface can be accessed
by configuration-space address using the ports shown in Table 2-14, page 26. Root Ports
must use the Configuration Port to set up the Configuration Space. Endpoints can also use
the Configuration Port to read and write; however, care must be taken to avoid adverse
system side effects.
The user application must supply the address as a DWORD address, not a byte address. To
calculate the DWORD address for a register, divide the byte address by four. For example:
•
The DWORD address of the Command/Status Register in the PCI Configuration Space
Header is 01h. (The byte address is 04h.)
•
The DWORD address for BAR0 is 04h. (The byte address is 10h.)
To read any register in configuration space, shown in Table 2-21, page 41, the user
application drives the register DWORD address onto cfg_dwaddr[9:0]. The core drives
the content of the addressed register onto cfg_do[31:0]. The value on cfg_do[31:0] is
qualified by signal assertion on cfg_rd_wr_done. Figure 3-60 illustrates an example with
two consecutive reads from the Configuration Space.
X-Ref Target - Figure 3-60
user_clk_out
cfg_mgmt_dwaddr[9:0]
cfg_mgmt_do[31:0]
A0
A1
D0
D1
cfg_mgmt_wr_en
cfg_mgmt_rd_en
cfg_mgmt_rd_wr_done
Figure 3-60:
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Configuration Space registers which are defined as RW by the PCI Local Bus Specification
and PCI Express Base Specification are writable through the Configuration Management
interface. To write a register in this address space, the user application drives the register
DWORD address onto cfg_dwaddr[9:0] and the data onto cfg_di[31:0]. This data is
further qualified by cfg_byte_en[3:0], which validates the bytes of data presented on
cfg_di[31:0]. These signals should be held asserted until cfg_rd_wr_done is asserted.
Figure 3-61 illustrates an example with two consecutive writes to the Configuration Space,
the first write with the user application writing to all 32 bits of data, and the second write
with the user application selectively writing to only bits [23:16].
Note: Writing to the Configuration Space could have adverse system side effects. Ensure these
writes do not negatively impact the overall system functionality.
X-Ref Target - Figure 3-61
user_clk_out
cfg_mgmt_dwaddr[9:0]
A0
A1
D
D
1111b
0100b
cfg_mgmt_di[31:0]
cfg_mgmt_byte_en[3:0]
cfg_mgmt_wr_en
cfg_mgmt_rd_en
cfg_mgmt_rd_wr_done
Figure 3-61:
Example Configuration Space Write Access
Optional PCI Express Extended Capabilities
The core optionally implements up to five PCI Express Extended Capabilities in the
following order:
1. Device Serial Number (DSN) Capability
2. Virtual Channel (VC) Capability
3. Vendor Specific (VSEC) Capability
4. Advanced Error Reporting (AER) Capability
5. Resizable BAR (RBAR) Capability
You can select which capabilities to enable in the Vivado IDE.
The Start addresses (Base Pointer address) of the five capability structures vary depending
on the combination of capabilities enabled.
Table 3-29 through Table 3-33 define the start addresses of the five Extended Capability
Structures, depending on the combination of PCI Express Extended Capabilities selected.
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Table 3-29:
DSN Base Pointer
DSN Base Pointer
No Capabilities Selected
-
DSN Enabled
Table 3-30:
100h
VC Capability Base Pointer
VC Capability Base Pointer
No Capabilities Selected
-
Only VC Capability Enabled
100h
DSN and VC Capability Enabled
10Ch
Table 3-31:
VSEC Capability Base Pointer
VSEC Capability Base Pointer
No Capabilities Selected
-
Only VSEC Capability Enabled
100h
DSN and VSEC Capability Enabled
10Ch
DSN, VC Capability, and VSEC Capability Enabled
128h
Table 3-32:
AER Capability Base Pointer
AER Capability Base Pointer
No Capabilities Selected
-
Only AER Capability Enabled
100h
DSN and AER Capability Enabled
10Ch
VC Capability and AER Capability Enabled
11Ch
VSEC Capability and AER Capability Enabled
118h
DSN, VC Capability, and AER Capability Enabled
128h
DSN, VSEC Capability, and AER Capability Enabled
124h
VC Capability, VSEC Capability, and AER Capability Enabled
134h
DSN, VC Capability, VSEC Capability, and AER Capability Enabled
140h
Table 3-33:
RBAR Capability Base Pointer
RBAR Capability Base Pointer
No Capabilities Selected
-
Only RBAR Capability Enabled
100h
DSN and RBAR Capability Enabled
10Ch
VC Capability and RBAR Capability Enabled
11Ch
VSEC Capability and RBAR Capability Enabled
118h
AER Capability and RBAR Capability Enabled
138h
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Table 3-33:
RBAR Capability Base Pointer (Cont’d)
RBAR Capability Base Pointer
DSN, VC Capability, and RBAR Capability Enabled
128h
DSN, VSEC Capability, and RBAR Capability Enabled
124h
DSN, AER Capability, and RBAR Capability Enabled
144h
VC Capability, VSEC Capability, and RBAR Capability Enabled
134h
VC Capability, AER Capability, and RBAR Capability Enabled
154h
VSEC Capability, AER Capability, and RBAR Capability Enabled
150h
DSN, VC Capability, VSEC Capability, and RBAR Capability Enabled
140h
DSN, VC Capability, AER Capability, and RBAR Capability Enabled
160h
DSN, VSEC Capability, AER Capability and RBAR Capability Enabled
15Ch
VC Capability, VSEC Capability, AER Capability, and RBAR Capability
Enabled
16Ch
DSN, VC Capability, VSEC Capability, AER Capability, and RBAR
Capability Enabled
178h
The rest of the PCI Express Extended Configuration Space is optionally available for you to
implement.
Xilinx Defined Vendor Specific Capability
The core supports Xilinx defined Vendor Specific Capability that provides Control and
Status for Loopback Master function for both the Root Port and Endpoint configurations.
RECOMMENDED: Use Loopback Master functionality to perform in-system test of the physical link only,
that is, when the application is not active.
User logic is required to control the Loopback Master functionality by assessing the VSEC
structure through the Configuration interface.
Figure 3-62 shows the VSEC structure in the PCIe Extended Configuration Space
implemented in the integrated block.
X-Ref Target - Figure 3-62
31
0 Byte Offset
Next Capability Offset
Capability Version = 1h
PCI Express extended capability = 000Bh
00h
VSEC Length = 24 bytes
VSEC Rev = 0h
VSEC ID = 0h
04h
Loopback Control Register
08h
Loopback Status Register
0Ch
Loopback Error Count Register 1
10h
Loopback Error Count Register 2
14h
Figure 3-62:
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Loopback Control Register (Offset 08h)
The Loopback Control Register controls Xilinx Defined Loopback specific parameters.
Table 3-34 shows the bit locations and definitions.
Table 3-34:
Loopback Control Register
Bit Location
Register Description
Attributes
0
Start Loopback: When set to 1b and pl_ltssm_state[5:0] is indicating L0
(16H), the block transitions to Loopback Master state and starts the
loopback test. When set to 0b, the block exits the loopback master mode.
RW
Note: The Start Loopback bit should not be set to 1b during a link
speed change.
1
Force Loopback: The loopback master can force the slave which fails to
achieve symbol lock at specified link speed and de-emphasis level to enter
the loopback.active state by setting this bit to 1b. The start bit must be set
to 1b when force is set to 1b.
RW
3:2
Loopback Link Speed: Advertised link speed in the TS1s sent by master with
loopback bit set to 1b. The master can control the loopback link speed by
properly controlling these bits.
RW
4
Loopback De-emphasis: Advertised de-emphasis level in the TS1s sent by
master. This also sets the De-emphasis level for the loopback slave.
RW
5
Loopback Modified Compliance: The loopback master generates modified
compliance pattern when in loopback mode else compliance pattern is
generated. Only one SKP OS is generated instead of two while in modified
compliance.
RW
6
Loopback Suppress SKP OS: When this bit is set to 1b then SKP OS are not
transmitted by Loopback Master. This bit is ignored when
send_modified_compliance pattern is set to 0b.
RW
15:7
Reserved
RO
23:16
Reserved
RO
31:24
Reserved
RO
Loopback Status Register (Offset 0Ch)
The Loopback Status Register provides information about Xilinx Defined Loopback specific
parameters. Table 3-35 shows the bit locations and definitions.
Table 3-35:
Loopback Status Register
Bit Location
Register Description
Attributes
0
Loopback Slave: This bit is set by hardware, if the device is currently in
loopback slave mode. When this bit is set to 1b, the Start Loopback bit must
not be set to 1b.
RO
1
Loopback Slave Failed: This bit is set by Loopback Master hardware, when
the master receives no TS1s while Loopback bit set to 1b, within 100 ms of
“Loopback.Active”. This bit is never set to 1b, when the Force Loopback bit
is set to 1b. Setting the Start Loopback bit to 1b clears this bit to 0b.
RO
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Table 3-35:
Loopback Status Register (Cont’d)
Bit Location
Register Description
Attributes
7:2
Reserved
RO
15:8
Loopback Tested: These bits are set to 0b, when the Start Loopback bit is
set to 1b. These bits are set to 1b when loopback test has been performed
on a given lane and the Loopback_Err_count_n for the corresponding lane
is valid.
Bit Positions
Lane
8
Lane 0 Tested
9
Lane 1 Tested
10
Lane 2 Tested
11
Lane 3 Tested
12
Lane 4 Tested
13
Lane 5 Tested
14
Lane 6 Tested
15
Lane 7 Tested
RO
31:16
Reserved
RO
Loopback Error Count Register 1 (Offset 10h)
The Loopback Error Count Register 1 provides information about the Error Count on the
Physical Lanes 0 - 3, as tested by Xilinx Defined Loopback Control Test. A lane has an error
count reported as zero if that lane was not tested in loopback. This could be if the lane is
either not part of a configured port or has not detected a receiver at the other end.
Table 3-36 shows the bit locations and definitions.
Table 3-36:
Loopback Error Count Register 1
Bit Location
Register Description
Attributes
7:0
Loopback Error Count 0: This specifies the Error Count on Lane 0. An error
is said to have occurred if there is an 8B/10B error or disparity error signaled
on the Lane. Setting Loopback Start bit to 1b clears the error count to 0h.
This is only valid when Loopback Tested: Lane 0 Tested is set to 1b.
RO
15:8
Loopback Error Count 1: This specifies the Error Count on Lane 1. An error
is said to have occurred if there is an 8B/10B error or disparity error signaled
on the Lane. Setting Loopback Start bit to 1b clears the error count to 0h.
This is only valid when Loopback Tested: Lane 1 Tested is set to 1b.
RO
23:16
Loopback Error Count 2: This specifies the Error Count on Lane 2. An error
is said to have occurred if there is an 8B/10B error or disparity error signaled
on the Lane. Setting Loopback Start bit to 1b clears the error count to 0h.
This is only valid when Loopback Tested: Lane 2 Tested is set to 1b.
RO
31:24
Loopback Error Count 3: This specifies the Error Count on Lane 3. An error
is said to have occurred if there is an 8B/10B error or disparity error signaled
on the Lane. Setting Loopback Start bit to 1b clears the error count to 0h.
This is only valid when Loopback Tested: Lane 3 Tested is set to 1b.
RO
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Loopback Error Count Register 2 (Offset 14h)
The Loopback Error Count Register 2 provides information about the Error Count on the
Physical Lanes 7 - 4, as tested by Xilinx Defined Loopback Control Test. A lane has an error
count reported as zero if that lane was not tested in loopback. This could be the case the
lane is either not part of configured port or has not detected a receiver at the other end.
Table 3-37 shows the bit locations and definitions.
Table 3-37:
Loopback Error Count Register 2
Bit Location
Register Description
Attributes
7:0
Loopback Error Count 4: This specifies the Error Count on Lane 4. An error
is said to have occurred if there is an 8B/10B error or disparity error signaled
on the Lane. Setting Loopback Start bit to 1b clears the error count to 0h.
This is only valid when Loopback Tested: Lane 4 Tested is set to 1b.
RO
15:8
Loopback Error Count 5: This specifies the Error Count on Lane 5. An error
is said to have occurred if there is an 8B/10B error or disparity error signaled
on the Lane. Setting Loopback Start bit to 1b clears the error count to 0h.
This is only valid when Loopback Tested: Lane 5 Tested is set to 1b.
RO
23:16
Loopback Error Count 6: This specifies the Error Count on Lane 6. An error
is said to have occurred if there is an 8B/10B error or disparity error signaled
on the Lane. Setting Loopback Start bit to 1b clears the error count to 0h.
This is only valid when Loopback Tested: Lane 6 Tested is set to 1b.
RO
31:24
Loopback Error Count 7: This specifies the Error Count on Lane 7. An error
is said to have occurred if there is an 8B/10B error or disparity error signaled
on the lane. Setting Loopback Start bit to 1b clears the error count to 0h.
This is only valid when Loopback Tested: Lane 7 Tested is set to 1b.
RO
Advanced Error Reporting Capability
The core implements the Advanced Error Reporting (AER) Capability structure as defined in
PCI Express Base Specification, rev. 2.1 [Ref 2]. All optional bits defined in the specification
are supported. Multiple Header Logging is not supported.
When AER is enabled, the core responds to error conditions by setting the appropriate
Configuration Space bit(s) and sending the appropriate error messages in the manner
described in PCI Express Base Specification, rev. 2.1.
For additional signaling requirements when AER is enabled, see AER Requirements,
page 128.
Resizable BAR Capability
The core implements the Resizable BAR Capability structure as defined in PCI Express Base
Specification, rev. 2.1. For more information on the Resizable BAR feature of the integrated
block, see Resizable BAR Implementation-Specific Information (Endpoint Only), page 129.
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User-Implemented Configuration Space
The core enables you to optionally implement registers in the PCI Configuration Space, the
PCI Express Extended Configuration Space, or both, in the user application. The user
application must return Config Completions for all address within this space. For more
information about enabling and customizing this feature, see Chapter 4, Customizing and
Generating the Core.
PCI Configuration Space
If you choose to implement registers within 0xA8 to 0xFF in the PCI Configuration Space,
the start address of the address region you wish to implement can be defined during the
core generation process.
The user application is responsible for generating all Completions to Configuration Reads
and Writes from the user-defined start address to the end of PCI Configuration Space
(0xFF). Configuration Reads to unimplemented registers within this range should be
responded to with a Completion with 0x00000000 as the data, and configuration writes
should be responded to with a successful Completion.
For example, to implement address range 0xC0 to 0xCF, there are several address ranges
defined that should be treated differently depending on the access. See Table 3-38 for
more details on this example.
Table 3-38:
Example: User-Implemented Space 0xC0 to 0xCF
Address Range
Configuration Writes
Configuration Reads
0x00 to 0xBF
The core responds automatically
The core responds automatically
0xC0 to 0xCF
The user application responds with
Successful Completion
The user application responds with
register contents
0xD0 to 0xFF
The user application responds with
Successful Completion
The user application responds with
0x00000000
PCI Express Extended Configuration Space
The starting address of the region in the PCI Express Extended Configuration Space that is
optionally available for you to implement depends on the PCI Express Extended Capabilities
that you enabled in the core.
The core allows you to select the start address of the user-implemented PCI Express
Extended Configuration Space, while generating and customizing the core. This space must
be implemented in the user application. The user application is required to generate a Cpld
with 0x00000000 for Configuration Read and successful Cpl for Configuration Write to
addresses in this selected range not implemented in the user application.
You can choose to implement a User Configuration Space with a start address not adjacent
to the last capability structure implemented by the core. In such a case, the core returns a
completion with 0x00000000 for configuration accesses to the region that you have
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chosen to not implement. Table 3-39 further illustrates this scenario.
Table 3-39:
Example: User-Defined Start Address for Configuration Space
Configuration Space
Byte Address
DSN Capability
100h - 108h
VSEC Capability
10Ch - 120h
Reserved Extended Configuration Space
(The core returns successful completion with 0x00000000)
124h - 164h
User-Implemented PCI Express Extended Configuration Space
168h - 47Ch
User-Implemented Reserved PCI Express Extended Configuration Space
(The user application returns successful completion with 0x00000000)
480h - FFFh
Table 3-39 illustrates an example Configuration of the PCI Express Extended Configuration
Space, with these settings:
•
DSN Capability Enabled
•
VSEC Capability Enabled
•
User Implemented PCI Express Extended Configuration Space Enabled
•
User Implemented PCI Express Extended Configuration Space Start Address 168h
In this configuration, the DSN Capability occupies the registers at 100h-108h, and the
VSEC Capability occupies registers at addresses 10Ch to 120h.
The remaining PCI Express Extended Configuration Space, starting at address 124h is
available to implement. For this example, registers in the address region starting 168h were
chosen for implement. The core returns successful completions with 0x00000000 for
Configuration accesses to registers 124h-164h. Table 3-39 also illustrates a case where
only registers from 168h to 47Ch are implemented. In this case, you are responsible for
returning successful Completions with 0x00000000 for configuration accesses to
480h-FFFh.
Additional Packet Handling Requirements
The user application must manage the mechanisms described in this section to ensure
protocol compliance, because the core does not manage them automatically.
Generation of Completions
The core does not generate Completions for Memory Reads or I/O requests made by a
remote device. You must service these completions according to the rules specified in the
PCI Express Base Specification [Ref 2].
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Tracking Non-Posted Requests and Inbound Completions
The integrated block does not track transmitted I/O requests or Memory Reads that have
yet to be serviced with inbound Completions. The user application is required to keep track
of such requests using the Tag ID or other information.
One Memory Read request can be answered by several Completion packets. The user
application must accept all inbound Completions associated with the original Memory Read
until all requested data has been received.
The PCI Express Base Specification requires that an Endpoint advertise infinite Completion
Flow Control credits as a receiver; the Endpoint can only transmit Memory Reads and I/O
requests if it has enough space to receive subsequent Completions.
The integrated block does not keep track of receive-buffer space for Completion. Rather, it
sets aside a fixed amount of buffer space for inbound Completions. The user application
must keep track of this buffer space to know if it can transmit requests requiring a
Completion response. See Appendix C, Managing Receive-Buffer Space for Inbound
Completions for Inbound Completions for more information.
Handling Message TLPs
By default, the 7 Series FPGAs Integrated Block for PCI Express does not route any received
messages to the AXI4-Stream interface. It signals the receipt of messages on the cfg_msg_*
interface. However, to receive these messages in addition to signaling on this interface,
enable this feature during customization of the core through the Vivado IDE.
Root Port Configuration
The Root Port of a PCI Express Root Complex does not send any internally generated
messages on the PCI Express link, although messages can still be sent through the
AXI4-Stream interface, such as a Set Slot Power Limit message. Any errors detected by the
Integrated Block in Root Port configuration that could cause an error message to be sent
are therefore signaled to the user application on the cfg_msg_* interface.
In Root Port configuration, the core also decodes received messages and signals these to
the user application on this interface. When configured as a Root Port, the integrated block
distinguishes between these received messages and error conditions detected internally by
the asserting the cfg_msg_received signal.
Reporting User Error Conditions
The user application must report errors that occur during Completion handling using
dedicated error signals on the core interface, and must observe the Device Power State
before signaling an error to the core. If the user application detects an error (for example,
a Completion Timeout) while the device has been programmed to a non-D0 state, the user
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application is responsible to signal the error after the device is programmed back to the D0
state.
After the user application signals an error, the core reports the error on the PCI Express Link
and also sets the appropriate status bit(s) in the Configuration Space. Because status bits
must be set in the appropriate Configuration Space register, the user application cannot
generate error reporting packets on the transmit interface. The type of error-reporting
packets transmitted depends on whether or not the error resulted from a Posted or
Non-Posted Request, and if AER is enabled or disabled. User-reported Posted errors cause
Message packets to be sent to the Root Complex if enabled to do so through the Device
Control Error Reporting bits and/or the Status SERR Enable bit, and the AER Mask bits (if
AER enabled). User-reported non-Posted errors cause Completion packets with
non-successful status to be sent to the Root Complex, unless the error is regarded as an
Advisory Non-Fatal Error. If AER is enabled, user-reported non-Posted errors can also cause
Message packets to be sent, if enabled by the AER Mask bits. For more information about
Advisory Non-Fatal Errors, see Chapter 6 of the PCI Express Base Specification. Errors on
Non-Posted Requests can result in either Messages to the Root Complex or Completion
packets with non-Successful status sent to the original Requester.
Error Types
The user application triggers different types of errors using the signals defined in
Table 2-18, page 34.
•
End-to-end CRC ECRC Error
•
Unsupported Request Error
•
Completion Timeout Error
•
Unexpected Completion Error
•
Completer Abort Error
•
Correctable Error
•
Atomic Egress Blocked Error
•
Multicast Blocked Error
•
Correctable Internal Error
•
Malformed Error
•
Poisoned Error
•
Uncorrectable Internal Error
Multiple errors can be detected in the same received packet; for example, the same packet
can be an Unsupported Request and have an ECRC error. If this happens, only one error
should be reported. Because all user-reported errors have the same severity, the user
application design can determine which error to report. The cfg_err_posted signal,
combined with the appropriate error reporting signal, indicates what type of
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Chapter 3: Designing with the Core
error-reporting packets are transmitted. The user application can signal only one error per
clock cycle. See Figure 3-63, Figure 3-64, and Figure 3-65, and Table 3-40 and Table 3-41.
The user application must ensure that the device is in a D0 Power state prior to reporting
any errors through the cfg_err_ interface. The user application can ensure this by
checking that the PMCSR PowerState (cfg_pmcsr_pme_powerstate[1:0]) is set to
2'b00. If the PowerState is not set to 2'b00 (the core is in a non-D0 power state) and
PME_EN cfg_pmcsr_pme_en is asserted (1'b1), you can assert (pulse) cfg_pm_wake and
wait for the Root to set the PMCSR PowerState bits to 2'b00. If the PowerState
(cfg_pmcsr_pme_powerstate) is not equal to 2'b00 and PME_EN cfg_pmcsr_pme_en
is deasserted (1'b0), you must wait for the Root to set the PowerState to 2'b00.
Table 3-40:
User-Indicated Error Signaling
User Reported Error
Internal Cause
AER Enabled
None
None
Don’t care
cfg_err_ur
&&
cfg_err_posted = 0
RX:
• Bar Miss (NP TLP)
• Locked TLP
• Type1 Cfg
• Non-Cpl TLP during
PM mode
• Poisoned TLP
cfg_err_ur
&&
cfg_err_posted = 1
RX:
• Bar Miss (Posted)
TLP
• Locked (Posted) TLP
• Posted TLP during
PM mode
cfg_err_cpl_abort
&&
cfg_err_posted = 0
cfg_err_cpl_abort
&&
cfg_err_posted = 1
cfg_err_cpl_timeout
&&
cfg_err_no_recovery = 0
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No action is taken.
No
A completion with an
Unsupported Request status is
sent.
Yes
A completion with an
Unsupported Request status is
sent. If enabled, a Correctable
Error Message is sent.
No
If enabled, a Non-Fatal Error
Message is sent.
Yes
Depending on the AER Severity
register, either a Non-Fatal or
Fatal Error Message is sent.
No
A completion with a Completer
Abort status is sent. If enabled,
a Non-Fatal Error Message is
sent.
Yes
A completion with a Completer
Abort status is sent. If enabled,
a Correctable Error Message is
sent.
No
A completion with a Completer
Abort status is sent. If enabled,
a Non-Fatal Error Message is
sent.
Yes
Depending on the AER Severity
register, either a Non-Fatal or
Fatal Error Message is sent.
No
None (considered an Advisory
Non-Fatal Error).
Yes
If enabled, a Correctable Error
Message is sent.
Poisoned TLP
ECRC Error
Poisoned TLP
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Table 3-40:
User-Indicated Error Signaling (Cont’d)
User Reported Error
Internal Cause
cfg_err_cpl_timeout
&&
cfg_err_no_recovery = 1
cfg_err_internal_cor
cfg_err_cpl_unexpect
Yes
Depending on the AER Severity
register, a Non-Fatal or Fatal
Error Message is sent.
No
If enabled, a Non-Fatal Error
Message is sent.
Yes
Depending on the AER Severity
register, either a Non-Fatal or
Fatal Error Message is sent.
Don't care
Yes
None (considered an Advisory
Non-Fatal Error).
Yes
If enabled, a Correctable Error
Message is sent.
No
None (considered an Advisory
Non-Fatal Error).
Yes
If enabled, a Correctable Error
Message is sent.
No
If enabled, a Fatal Error
Message is sent.
Yes
Depending on the AER Severity
register, either a Non-Fatal or
Fatal Error Message is sent.
No
If enabled, a Non-Fatal Error
Message is sent.
Yes
Depending on the AER Severity
register, either a Non-Fatal or
Fatal Error Message is sent.
No
None (considered an Advisory
Non-Fatal Error).
Yes
If enabled, a Correctable Error
Message is sent.
Poisoned TLP
RX:
• Out-of-range ACK/
NAK
• Malformed TLP
• Buffer Overflow
• FC error
cfg_err_mc_blocked
cfg_err_poisoned
&&
cfg_err_no_recovery = 0
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Poisoned TLP
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If enabled, a Correctable Error
Message is sent.
No
Poisoned TLP
cfg_err_atomic_egress_blo
cked
cfg_err_malformed
If enabled, a Non-Fatal Error
Message is sent.
ECRC Error
RX:
• PLM MGT Err
• Replay TO
• Replay Rollover
• Bad DLLP
• Bad TLP (crc/seq#)
• Header Log
Overflow (1)
Action
No
ECRC Error
cfg_err_ecrc
cfg_err_cor
AER Enabled
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Table 3-40:
User-Indicated Error Signaling (Cont’d)
User Reported Error
Internal Cause
cfg_err_poisoned
&&
cfg_err_no_recovery = 1
AER Enabled
Action
No
If enabled, a Non-Fatal Error
Message is sent.
Yes
Depending on the AER Severity
register, either a Non-Fatal or
Fatal Error Message is sent.
ECRC Error
Notes:
1. Only when AER is enabled.
Table 3-41:
Possible Error Conditions for TLPs Received by the User Application
Error Qualifying Signal
Status
Possible Error Condition
Completion
Abort
(cfg_err_cpl_
abort)
Correctable
Error
(cfg_err_
cor)
ECRC Error
(cfg_err_
ecrc)
Memory
Write
3
X
N/A
3
X
1
No
Memory
Read
3
3
N/A
3
X
0
Yes
I/O
3
3
N/A
3
X
0
Yes
Completion
X
X
N/A
3
3
1
No
Received TLP Type
Unsupported
Request
(cfg_err_ur)
Unexpected Value to Drive
Drive Data
Completion
(cfg_err_ on (cfg_err_tlp_
(cfg_err_cpl_ onposted)
cpl header[47:0])
unexpect)
Notes:
1. A checkmark indicates a possible error condition for a given TLP type. For example, you can signal Unsupported Request or ECRC
Error for a Memory Write TLP, if these errors are detected. An X indicates not a valid error condition for a given TLP type. For
example, you should never signal Completion Abort in response to a Memory Write TLP.
Whenever an error is detected in a Non-Posted Request, the user application deasserts
cfg_err_posted and provides header information on
cfg_err_tlp_cpl_header[47:0] during the same clock cycle the error is reported, as
illustrated in Figure 3-63. The additional header information is necessary to construct the
required Completion with non-Successful status. Additional information about when to
assert or deassert cfg_err_posted is provided in the remainder of this section.
If an error is detected on a Posted Request, the user application instead asserts
cfg_err_posted, but otherwise follows the same signaling protocol. This results in a
Non-Fatal Message to be sent, if enabled (see Figure 3-64).
If several non-Posted errors are signaled on cfg_err_ur or cfg_err_cpl_abort in a
short amount of time, it is possible for the core to be unable to buffer them all. If that
occurs, cfg_err_cpl_rdy is deasserted and you must cease signaling those types of
errors on the same cycle. You must not resume signaling those types of errors until
cfg_err_cpl_rdy is reasserted.
The ability of the core to generate error messages can be disabled by the Root Complex
issuing a configuration write to the Endpoint core Device Control register and the PCI
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Command register setting the appropriate bits to 0. For more information about these
registers, see Chapter 7 of the PCI Express Base Specification [Ref 2]. However,
error-reporting status bits are always set in the Configuration Space whether or not their
Messages are disabled.
If AER is enabled, the root complex has fine-grained control over the ability and types of
error messages generated by the Endpoint core by setting the Severity and Mask Registers
in the AER Capability Structure. For more information about these registers, see Chapter 7
of the PCI Express Base Specification, rev. 2.1.
X-Ref Target - Figure 3-63
user_clk_out
cfg_err_cpl_rdy
cfg_err_tlp_cpl_header[47:0]
cfg_err_ur
cfg_err_posted
cfg_err_locked
cfg_dcommand[3]
tx_data[63:0]*
Cpl UR
Completion with Status Unsupported Request sent on link
* Internal signal not appearing on User Interface
Figure 3-63:
Signaling Unsupported Request for Non-Posted TLP
X-Ref Target - Figure 3-64
user_clk_out
cfg_err_cpl_rdy
cfg_err_ur
cfg_err_posted
cfg_dcommand[1]
tx_data[63:0]*
Message
Non-Fatal Error Message sent on link
* Internal signal not appearing on User Interface
Figure 3-64:
Signaling Unsupported Request for Posted TLP
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X-Ref Target - Figure 3-65
user_clk_out
cfg_err_cpl_rdy
cfg_err_tlp_cpl_header[47:0]
cfg_err_ur
cfg_err_posted
cfg_err_locked
cfg_dcommand[3]
tx_data[63:0]*
Cpl UR
Completion with Status Unsupported Request sent on link
* Internal signal not appearing on User Interface
Figure 3-65:
Signaling Locked Unsupported Request for Locked Non-Posted TLP
Completion Timeouts
The core does not implement Completion timers; for this reason, the user application must
track how long its pending Non-Posted Requests have each been waiting for a Completion
and trigger timeouts on them accordingly. The core has no method of knowing when such
a timeout has occurred, and for this reason does not filter out inbound Completions for
expired requests.
If a request times out, the user application must assert cfg_err_cpl_timeout, which
causes an error message to be sent to the Root Complex. If a Completion is later received
after a request times out, the user application must treat it as an Unexpected Completion.
Unexpected Completions
The core automatically reports Unexpected Completions in response to inbound
Completions whose Requestor ID is different than the Endpoint ID programmed in the
Configuration Space. These completions are not passed to the user application. The current
version of the core regards an Unexpected Completion to be an Advisory Non-Fatal Error
(ANFE), and no message is sent.
Completer Abort
If the user application is unable to transmit a normal Completion in response to a
Non-Posted Request it receives, it must signal cfg_err_cpl_abort. The
cfg_err_posted signal can also be set to 1 simultaneously to indicate Non-Posted and
the appropriate request information placed on cfg_err_tlp_cpl_header[47:0]. This
sends a Completion with non-Successful status to the original Requester, but does not send
an Error Message. When in Legacy mode if the cfg_err_locked signal is set to 0 (to
indicate the transaction causing the error was a locked transaction), a Completion Locked
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with Non-Successful status is sent. If the cfg_err_posted signal is set to 1 (to indicate a
Posted transaction), no Completion is sent, but a Non-Fatal Error Message is sent (if
enabled).
Unsupported Request
If the user application receives an inbound Request it does not support or recognize, it
must assert cfg_err_ur to signal an Unsupported Request. The cfg_err_posted signal
must also be asserted or deasserted depending on whether the packet in question is a
Posted or Non-Posted Request. If the packet is Posted, a Non-Fatal Error Message is sent
out (if enabled); if the packet is Non-Posted, a Completion with a non-Successful status is
sent to the original Requester. When in Legacy mode if the cfg_err_locked signal is set
to 1 (to indicate the transaction causing the error was a locked transaction), a Completion
Locked with Unsupported Request status is sent.
The Unsupported Request condition can occur for several reasons, including:
•
An inbound Memory Write packet violates the programming model of the user
application, for example, if the user application is allotted a 4 KB address space but
only uses 3 KB, and the inbound packet addresses the unused portion.
Note: If this occurs on a Non-Posted Request, the user application should use
cfg_err_cpl_abort to flag the error.
•
An inbound packet uses a packet Type not supported by the user application, for
example, an I/O request to a memory-only device.
ECRC Error
When enabled, the core automatically checks the ECRC field for validity. If an ECRC error is
detected, the core responds by setting the appropriate status bits and an appropriate error
message is sent, if enabled to do so in the configuration space.
If automatic ECRC checking is disabled, the user application can still signal an ECRC error by
asserting cfg_err_ecrc. The user application should only assert cfg_err_ecrc if AER is
disabled.
AER Requirements
Whenever the user application signals an error using one of the cfg_err_* inputs (for
example, cfg_err_ecrc_n), it must also log the header of the TLP that caused the error.
The user application provides header information on cfg_err_aer_headerlog[127:0]
during the same clock cycle the error is reported. The user application must hold the header
information until cfg_err_aer_headerlog_set is asserted.
cfg_err_aer_headerlog_set remains asserted until the Uncorrectable Error Status
Register bit corresponding to the first error pointer is cleared (typically, through system
software – see the PCI Express Base Specification, v2.1 [Ref 2]). If
cfg_err_aer_headerlog_set is already asserted, there is already a header logged.
Figure 3-66 illustrates the operation for AER header logging.
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X-Ref Target - Figure 3-66
user_clk
cfg_err_<condition>
cfg_err_aer_headerlog[127:0]
H0H1H2[H3]
Header of TLP with Error
cfg_err_aer_headerlog_set
Cleared by Software
Figure 3-66:
AER Header Logging
Resizable BAR Implementation-Specific Information (Endpoint Only)
The integrated block can support up to six resizable BARs; however, the BAR Index field of
the Resizable BAR Capability Registers (0 through 5) must be in ascending order. For
example, if Bar Index (0) is set to 4 (indicating it points to the BAR[4]), Bar Index (1) can be
set to 5 and Bar Index (2 - 5) cannot be used and is disabled. In this example, if BAR[4]
represents a 64-bit BAR (using BAR5 for the upper 32 bits), Bar Index(1) cannot be used.
When the Bar Size field of a Resizable BAR Capability is programmed, any value previously
programmed in the corresponding BAR is cleared and the number of writable bits in that
BAR is immediately changed to reflect the new size.
Error Detection
The PCI Express Base Specification identifies a number of errors a PCIe port should check for,
and a number of additional optional checks.
Most of the required checks (including several of the optional checks) are carried out by the
integrated block. Some, however, need to be implemented. The integrated block performs
checks on received TLPs only. You must perform all checks on transmit TLPs. Details of
checks made by the integrated block or you are shown in Table 3-42. This table is organized
broadly in line with the sections of the PCI Express Base Specification describing how these
checks should be made.
Table 3-42:
Error Checking Summary
PCI Express Check is Where Check
Specification Required
is
Section
or Optional Implemented
Checks Made Regarding TLPs with Data Payloads
That the data payload of a TLP does not exceed Max_Payload_Size.
Any TLP that violates this rule is a Malformed TLP.
2.2.2
Required
Integrated
Block
That where a TLP includes data, the actual amount of data matches
the value in the length field. Any TLP that violates this rule is a
Malformed TLP.
2.2.2
Required
Integrated
Block
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Table 3-42:
Error Checking Summary (Cont’d)
PCI Express Check is Where Check
Specification Required
is
Section
or Optional Implemented
Checks Made Regarding TLP Digests
That the presence (or absence) of a digest correctly reflects the
setting of the TD field. Any TLP that violates this rule is a Malformed
TLP.
2.2.3
Required
Integrated
Block
2.2.5
Optional
User
That the tag field is the correct length for the current configuration.
You must check the tag field for received and transmitted memory
and I/O requests.
2.2.6.2
Optional
Integrated
Block
That MWr requests do not specify an Address/Length combination
that causes a Memory Space access to cross a 4 KB boundary. Any
MWr request that violates this rule is treated as a Malformed TLP. For
MRd requests, this optional check should be implemented in the
FPGA logic, if desired.
2.2.7
Optional
Integrated
Block
That I/O requests obey these restrictions:
• TC[2:0] must be 000b
• Attr[1:0] must be 00b
• AT[1:0] must be 00b
• Length[9:0] must be 00 0000 0001b
• The last DW BE[3:0] must be 0000b
Any I/O request that violates this rule is treated as a Malformed TLP.
2.2.7
Optional
Integrated
Block
That configuration requests obey these restrictions:
• TC[2:0] must be 000b
• Attr[1:0] must be 00b
• AT[1:0] must be 00b
• Length[9:0] must be 00 0000 0001b
• The last DW BE[3:0] must be 0000b
Any configuration request that violates this rule is treated as a
Malformed TLP.
2.2.7
Optional
Integrated
Block
That configuration requests address a valid function number field.
7.3.2
Required
Integrated
Block
2.2.8.1
Optional
Integrated
Block
Checks Made Regarding First/Last DWORD Byte Enable (1 DWORD = 32 bits)
•
•
•
•
That if length > 1 DWORD, then the first DWORD BE is not 0000
That if length = 1 DWORD, then the last DWORD BE is 0000
That if length > 1 DWORD, then the last DWORD BE is not 0000
That the BEs are not non-contiguous for packets ≥ 3DW in length
or 2 DWORD packets that are not QWORD aligned
Any TLP that violates these rules is a Malformed TLP.
Checks Made Regarding Memory, I/O, and Configuration Requests
Checks Made Regarding Message Requests
That Assert_INTx/Deassert_INTx Messages are only issued by
upstream Ports. Any Assert_INTx/Deassert_INTx Message that
violates this rule is treated as a Malformed TLP.
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Table 3-42:
Error Checking Summary (Cont’d)
PCI Express Check is Where Check
Specification Required
is
Section
or Optional Implemented
That Assert_INTx/Deassert_INTx Messages use TC0. Any Assert_INTx/
Deassert_INTx Message that violates this rule is treated as a
Malformed TLP.
2.2.8.1
Required
Integrated
Block
That Power Management Messages use TC0. Any PM Message that
violates this rule is treated as a Malformed TLP.
2.2.8.2
Required
Integrated
Block
That Error Signaling Messages use TC0. Any Error Signaling Message
that violates this rule is treated as a Malformed TLP.
2.2.8.3
Required
Integrated
Block
That Unlock Messages use TC0. Any Unlock Message that violates
this rule is treated as a Malformed TLP.
2.2.8.4
Required
Integrated
Block
That Set_Slot_Power_Limit Messages use TC0. Any
Set_Slot_Power_Limit message that violates this rule is treated as a
Malformed TLP.
2.2.8.5
Required
Integrated
Block
Unsupported Type 0 Vendor-Defined Messages. Reported as
unsupported requests.
Note: Type 1 Vendor-Defined Messages should be ignored.
2.2.8.6
Required
User
2.2.8.6, 2.2.8.7
Required
User
That Latency Tolerance Reporting Messages use TC0. Any Latency
Tolerance Reporting message that violates this rule is treated as a
Malformed TLP.
2.2.8.8
Optional
User
The TLPs containing a TLP Prefix must have an underlying TLP
Header. A TLP that violates this rule is treated as a Malformed TLP.
2.2.10
Optional
User
That in a TLPs containing a combinations of Local and End-End TLP
Prefixes, all Local TLP Prefixes precede any End-End TLP Prefixes. Any
TLP that violates this rule is treated as a Malformed TLP.
2.2.10
Optional
User
It is an error to receive a TLP with a Local TLP Prefix type not
supported by the Receiver. If the Extended Fmt Field Supported bit is
set, any TLP that violates this rule is treated as a Malformed TLP.
2.2.10.1
Optional
User
That the maximum number of End-End TLP Prefixes permitted in a
TLP is 4. Any TLP that violates this rule is treated as a Malformed TLP.
2.2.10.2
Optional
User
It is an error to receive a TLP with End-End TLP Prefix by a Receiver
that does not support End-End Prefixes. Any TLP that violates this
rule is treated as a Malformed TLP.
2.2.10.2
Optional
User
2.3
Optional
User
Unsupported messages, that is, all messages other than:
• Supported Type 0 Vendor-Defined Messages (message code
01111110)
• Type 1 Vendor-Defined Messages (message code 01111111)
• Ignored Messages (messages codes 01000000, 01000001,
01000011, 01000100, 01000101, 01000111, 01001000)
Reported as unsupported requests.
Checks Made Regarding Handling of TLPs
If the Extended Fmt Field Supported bit is set, Received TLPs that use
encodings of Fmt and Type that are Reserved are treated as
Malformed TLPs.
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Table 3-42:
Error Checking Summary (Cont’d)
PCI Express Check is Where Check
Specification Required
is
Section
or Optional Implemented
That TLPs with Fmt[2] clear and that use undefined Type field values
are treated as Malformed TLPs.
2.3
Optional
User
That any received TLP passes the required and implemented optional
checks on TLP formation. Any TLP that violates this rule is a
malformed TLP. You must generate the appropriate completion TLP.
2.3
Required
Integrated
Block
That Memory Read Request-Locked (MRdLk) requests do not include
a payload. You must discard any MRdLk requests with payload and
signal a malformed TLP.
2.3
Required
User
That a Completion with Data (CplD) has a 3DW header. Any CplD with
a 4DW header must be discarded and a malformed TLP must be
signaled.
2.3
Required
User
That an I/O request has a 3DW header. Any I/O request with a 4DW
header must be discarded and a malformed TLP must be signaled.
2.2.7
Required
User
That the byte enable rules for received memory reads are followed.
If not, TLP must be discarded and a malformed TLP must be signaled.
2.2.5
Required
User
Unsupported request types. Reported as an unsupported request.
You must generate the appropriate completion TLP.
2.3.1
Required
Integrated
Block
Requests that violate the programming model of the device.
Reported as a completer abort. You must generate the appropriate
completion TLP.
2.3.1
Optional
User
Requests that cannot be processed due to a device-specific error
condition. Reported as a completer abort. You must generate the
appropriate completion TLP.
2.3.1
Required
User
That completions do not include more data than permitted by the
Max_Payload_Size. Any completion that violates this rule is treated as
a Malformed TLP.
2.3.1.1
Required
Integrated
Block
Violations of RCB. Any completion that violates the RCB rules is
treated as a Malformed TLP.
2.3.1.1
Optional
User
Unexpected completions.
2.3.2
Required
User
Completions with a status of request retry for requests other than
configuration requests. Treated as a malformed TLP.
2.3.2
Optional
User
Completions with a completion status of unsupported request or
completer abort. Reported through conventional PCI reporting
mechanisms.
2.3.2
Required
User
2.5
Optional
User
Checks Made Regarding Request Handling
Checks Made Regarding Completion Handling
Checks Made Regarding Virtual Channel Mechanism
That requesters that do not support the VC capability structure only
operate on TC0. Received requests on TC1-TC7 must be handled
normally (without error) and completions must be returned on the
same TC in which the request was received.
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Table 3-42:
Error Checking Summary (Cont’d)
PCI Express Check is Where Check
Specification Required
is
Section
or Optional Implemented
That the TC associated with each TLP is mapped to an enabled VC at
an Ingress Port. Any TLP that violates this rule is treated as a
Malformed TLP.
2.5.3
Required
Integrated
Block
That the initial FC value is greater than or equal to the minimum
advertisement. Reported as a flow control protocol error. Requires
knowledge of the device and the Max Payload Size setting at the far
end of the link.
2.6.1
Optional
User
That no receiver ever cumulatively issues more than 2047
outstanding unused data credits or 127 outstanding unused header
credits. Reported as a flow control protocol error.
2.6.1
Optional
Integrated
Block
That if infinite credits are advertised during initialization, all updates
must also be infinite. Reported as a flow control protocol error. This
also applies where just a header or just the data has been advertised
as infinite.
2.6.1
Optional
Integrated
Block
That the VC used by a TLP has been enabled. Any TLP that violates
this rule is treated as a Malformed TLP.
2.6.1
Required
Integrated
Block
Receiver Overflow. The PCI Express Base Specification defines this as
happening where the number of TLPs exceeds CREDITS_ALLOCATED.
2.6.1.2
Optional
Integrated
Block
That Update FCPs are scheduled for transmission at the specified
interval.
2.6.1.2
Optional
Integrated
Block
2.7.1
Required
Integrated
Block(1)
2.7.2.2
Required
User
2.8
Required
User
Checks Made Regarding Flow Control
Checks Made Regarding Data Integrity
Integrity of TD bit in messages received and forwarded by switches.
Any failed ECRC checks are reported.
Receipt of a Poisoned TLP.
Checks Made Regarding Completion Timeout
That the completion timeout timer does not expire in less than 50 µs
but must expire if a request is not completed in 50 ms.
Checks Made Regarding LCRC and Sequence Number (TLP Transmitter)
REPLAY_NUM rolling over from 11b to 00b. Causes the Transmitter
to: (a) report an error; (b) signal the Physical Layer to retrain the Link.
3.5.2.1
Required
Integrated
Block
Retry buffer containing TLPs for which no Ack or Nak DLLP has been
received for a period exceeding specified maximum time. Causes the
Transmitter to: (a) report an error; (b) initiate a replay.
3.5.2.1
Required
Integrated
Block
Value in the CRC field of all received DLLPs compared with calculated
result. If not equal: (a) the DLLP is discarded as corrupt; (b) an error
is reported.
3.5.2.1
Required
Integrated
Block
Sequence Number specified by the AckNak_Seq_Num compared
with that of unacknowledged TLPs and value in ACKD_SEQ. If no
match found: (a) the DLLP is discarded; (b) a DLLP error is reported.
3.5.2.1
Required
Integrated
Block
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Table 3-42:
Error Checking Summary (Cont’d)
PCI Express Check is Where Check
Specification Required
is
Section
or Optional Implemented
Checks Made Regarding LCRC and Sequence Number (TLP Receiver)
LCRC field of the received TLP compared with calculated result. If not
equal: (a) the TLP is discarded as corrupt; (b) an error is reported.
3.5.3.1
Required
Integrated
Block
LCRC field of the received TLP compared with logical NOT of
calculated result if TLP end framing symbol is EDB. LCRC does not
match logical NOT of the calculated value: (a) the TLP is discarded as
corrupt; (b) an error is reported.
3.5.3.1
Required
Integrated
Block
TLP Sequence Number compared with expected value stored in
NEXT_RCV_SEQ. If not equal, an error is reported.
3.5.3.1
Required
Integrated
Block
Validity of received 8B/10B symbols bearing in mind the running
disparity. Errors reported as Receiver Errors.
4.2.1.3
Required
Integrated
Block
Framing Errors, Loss of Symbol Lock, Lane Deskew Errors, and
Elasticity Buffer Overflow/Underflow. Errors reported as Receiver
Errors.
4.2.2.1
Optional
User
Checks Resulting in Receiver Errors
Notes:
1. The integrated block checks the ECRC depending on the customizable ECRC check setting.
Power Management
The core supports these power management modes:
•
Active State Power Management (ASPM)
•
Programmed Power Management (PPM)
Implementing these power management functions as part of the PCI Express design
enables the PCI Express hierarchy to seamlessly exchange power-management messages to
save system power. All power management message identification functions are
implemented. The subsections in this section describe the user logic definition to support
the above modes of power management.
For additional information on ASPM and PPM implementation, see the PCI Express Base
Specification [Ref 2].
Active State Power Management
The Active State Power Management (ASPM) functionality is autonomous and transparent
from a user-logic function perspective. The core supports the conditions required for ASPM.
The integrated block supports ASPM L0s.
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Programmed Power Management
To achieve considerable power savings on the PCI Express hierarchy tree, the core supports
these link states of Programmed Power Management (PPM):
•
L0: Active State (data exchange state)
•
L1: Higher Latency, lower power standby state
•
L3: Link Off State
The Programmed Power Management Protocol is initiated by the Downstream Component/
Upstream Port.
PPM L0 State
The L0 state represents normal operation and is transparent to the user logic. The core
reaches the L0 (active state) after a successful initialization and training of the PCI Express
Link(s) as per the protocol.
PPM L1 State
These steps outline the transition of the core to the PPM L1 state:
1. The transition to a lower power PPM L1 state is always initiated by an upstream device,
by programming the PCI Express device power state to D3-hot (or to D1 or D2 if they are
supported).
2. The device power state is communicated to the user logic through the
cfg_pmcsr_powerstate[1:0] output.
3. The core then throttles/stalls the user logic from initiating any new transactions on the
user interface by deasserting s_axis_tx_tready. Any pending transactions on the
user interface are, however, accepted fully and can be completed later.
There are two exceptions to this rule:
°
°
The core is configured as an Endpoint and the User Configuration Space is enabled.
In this situation, you must refrain from sending new Request TLPs if
cfg_pmcsr_powerstate[1:0] indicates non-D0, but youcan return Completions
to Configuration transactions targeting User Configuration space.
The core is configured as a Root Port. To be compliant in this situation, refrain from
sending new Requests if cfg_pmcsr_powerstate[1:0] indicates non-D0.
4. The core exchanges appropriate power management DLLPs with its link partner to
successfully transition the link to a lower power PPM L1 state. This action is transparent
to the user logic.
5. All user transactions are stalled for the duration of time when the device power state is
non-D0, with the exceptions indicated in step 3.
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Note: The user logic, after identifying the device power state as non-D0, can initiate a request
through the cfg_pm_wake to the upstream link partner to configure the device back to the D0
power state. If the upstream link partner has not configured the device to allow the generation of
PM_PME messages (cfg_pmcsr_pme_en = 0), the assertion of cfg_pm_wake is ignored by the
core.
PPM L3 State
These steps outline the transition of the Endpoint for PCI Express to the PPM L3 state:
1. The core negotiates a transition to the L23 Ready Link State upon receiving a
PME_Turn_Off message from the upstream link partner.
2. Upon receiving a PME_Turn_Off message, the core initiates a handshake with the user
logic through cfg_to_turnoff (see Table 3-43) and expects a cfg_turnoff_ok
back from the user logic.
3. A successful handshake results in a transmission of the Power Management Turn-off
Acknowledge (PME-turnoff_ack) Message by the core to its upstream link partner.
4. The core closes all its interfaces, disables the Physical/Data-Link/Transaction layers and
is ready for removal of power to the core.
There are two exceptions to this rule:
°
°
The core is configured as an Endpoint and the User Configuration Space is enabled.
In this situation, refrain from sending new Request TLPs if
cfg_pmcsr_powerstate[1:0] indicates non-D0, but you can return
Completions to Configuration transactions targeting User Configuration space.
The core is configured as a Root Port. To be compliant in this situation, refrain from
sending new Requests if cfg_pmcsr_powerstate[1:0] indicates non-D0.
Table 3-43:
Power Management Handshaking Signals
Port Name
Direction
Description
cfg_to_turnoff
Output
Asserted if a power-down request TLP is received from the
upstream device. After assertion, cfg_to_turnoff remains
asserted until the user application asserts cfg_turnoff_ok.
cfg_turnoff_ok
Input
Asserted by the user application when it is safe to power down.
Power-down negotiation follows these steps:
1. Before power and clock are turned off, the Root Complex or the Hot-Plug controller in a
downstream switch issues a PME_Turn_Off broadcast message.
2. When the core receives this TLP, it asserts cfg_to_turnoff to the user application and
starts polling the cfg_turnoff_ok input.
3. When the user application detects the assertion of cfg_to_turnoff, it must complete
any packet in progress and stop generating any new packets. After the user application
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is ready to be turned off, it asserts cfg_turnoff_ok to the core. After assertion of
cfg_turnoff_ok, the user application has committed to being turned off.
4. The core sends a PME_TO_Ack when it detects assertion of cfg_turnoff_ok, as
displayed in Figure 3-67 (64-bit).
X-Ref Target - Figure 3-67
user_clk_out
rx_data[63:0]*
PME_Turn_Off
cfg_to_turnoff
cfg_turnoff_ok
tx_data[63:0]*
PME_TO_ACK
* Internal signal not appearing on User Interface
Figure 3-67:
Power Management Handshaking: 64-Bit
Generating Interrupt Requests
Note: This section is only applicable to the Endpoint Configuration of the 7 Series FPGAs Integrated
Block for PCI Express core.
The core supports sending interrupt requests as either legacy, Message MSI, or MSI-X
interrupts. The mode is programmed using the MSI Enable bit in the Message Control
Register of the MSI Capability Structure and the MSI-X Enable bit in the MSI-X Message
Control Register of the MSI-X Capability Structure. For more information on the MSI and
MSI-X capability structures, see section 6.8 of the PCI Local Base Specification v3.0 [Ref 2].
The state of the MSI Enable and MSI-X Enabled bits are reflected by the
cfg_interrupt_msienable and cfg_interrupt_msixeable outputs, respectively.
Table 3-44 describes the Interrupt Mode the device has been programmed to, based on the
cfg_interrupt_msienable and cfg_interrupt_msixenable outputs of the core.
Table 3-44:
Interrupt Modes
cfg_interrupt_
msienable=0
cfg_interrupt_
msienable=1
cfg_interrupt_msixenable=0
cfg_interrupt_msixenable=1
Legacy Interrupt (INTx) mode.
The cfg_interrupt interface only sends
INTx messages.
MSI-X mode. You must generate MSI-X
interrupts by composing MWr TLPs on the
transmit AXI4-Stream interface; Do not use
the cfg_interrupt interface.
The cfg_interrupt interface is active and
sends INTx messages, but refrain from
doing so.
MSI mode. The cfg_interrupt interface
only sends MSI interrupts (MWr TLPs).
Undefined. System software is not
supposed to permit this.
However, the cfg_interrupt interface is
active and sends MSI interrupts (MWr TLPs)
if you choose to do so.
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The MSI Enable bit in the MSI control register, the MSI-X Enable bit in the MSI-X Control
Register, and the Interrupt Disable bit in the PCI Command register are programmed by the
Root Complex. The user application has no direct control over these bits.
The Internal Interrupt Controller in the core only generates Legacy Interrupts and MSI
Interrupts. MSI-X Interrupts need to be generated by the user application and presented on
the transmit AXI4-Stream interface. The status of cfg_interrupt_msienable
determines the type of interrupt generated by the internal Interrupt Controller:
If the MSI Enable bit is set to a 1, then the core generates MSI requests by sending Memory
Write TLPs. If the MSI Enable bit is set to 0, the core generates legacy interrupt messages as
long as the Interrupt Disable bit in the PCI Command Register is set to 0:
•
cfg_command[10] = 0: INTx interrupts enabled
•
cfg_command[10] = 1: INTx interrupts disabled (request are blocked by the core)
•
cfg_interrupt_msienable = 0: Legacy Interrupt
•
cfg_interrupt_msienable = 1: MSI
Regardless of the interrupt type used (Legacy or MSI), initiate interrupt requests through
cfg_interrupt and cfg_interrupt_rdy as shown in Table 3-45.
Table 3-45:
Interrupt Signalling
Port Name
cfg_interrupt
cfg_interrupt_rdy
Direction
Input
Output
Description
Assert to request an interrupt. Leave asserted until the interrupt is
serviced.
Asserted when the core accepts the signaled interrupt request.
The user application requests interrupt service in one of two ways, each of which are
described next.
Legacy Interrupt Mode
•
As shown in Figure 3-68, the user application first asserts cfg_interrupt and
cfg_interrupt_assert to assert the interrupt. The user application should select a
specific interrupt (INTA) using cfg_interrupt_di[7:0] as shown in Table 3-46.
•
The core then asserts cfg_interrupt_rdy to indicate the interrupt has been
accepted. On the following clock cycle, the user application deasserts cfg_interrupt
and, if the Interrupt Disable bit in the PCI Command register is set to 0, the core sends
an assert interrupt message (Assert_INTA).
•
After the user application has determined that the interrupt has been serviced, it
asserts cfg_interrupt while deasserting cfg_interrupt_assert to deassert the
interrupt. The appropriate interrupt must be indicated by cfg_interrupt_di[7:0].
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•
The core then asserts cfg_interrupt_rdy to indicate the interrupt deassertion has
been accepted. On the following clock cycle, the user application deasserts
cfg_interrupt and the core sends a deassert interrupt message (Deassert_INTA).
X-Ref Target - Figure 3-68
user_clk_out
cfg_interrupt_msienable
cfg_interrupt
cfg_interrupt_di
INTA
cfg_interrupt_assert
cfg_interrupt_rdy
cfg_interrupt_msienable
cfg_interrupt
cfg_interrupt_di
01h
cfg_interrupt_rdy
Figure 3-68:
Table 3-46:
Requesting Interrupt Service: MSI and Legacy Mode
Legacy Interrupt Mapping
cfg_interrupt_di[7:0] value
Legacy Interrupt
00h
INTA
01h - FFh
Not Supported
MSI Mode
•
As shown in Figure 3-68, the user application first asserts cfg_interrupt.
Additionally the user application supplies a value on cfg_interrupt_di[7:0] if
Multi-Vector MSI is enabled.
•
The core asserts cfg_interrupt_rdy to signal that the interrupt has been accepted
and the core sends a MSI Memory Write TLP. On the following clock cycle, the user
application deasserts cfg_interrupt if no further interrupts are to be sent.
The MSI request is either a 32-bit addressable Memory Write TLP or a 64-bit addressable
Memory Write TLP. The address is taken from the Message Address and Message Upper
Address fields of the MSI Capability Structure, while the payload is taken from the Message
Data field. These values are programmed by the system software through configuration
writes to the MSI Capability structure. When the core is configured for Multi-Vector MSI,
system software can permit Multi-Vector MSI messages by programming a non-zero value
to the Multiple Message Enable field.
The type of MSI TLP sent (32-bit addressable or 64-bit addressable) depends on the value
of the Upper Address field in the MSI capability structure. By default, MSI messages are sent
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as 32-bit addressable Memory Write TLPs. MSI messages use 64-bit addressable Memory
Write TLPs only if the system software programs a non-zero value into the Upper Address
register.
When Multi-Vector MSI messages are enabled, the user application can override one or
more of the lower-order bits in the Message Data field of each transmitted MSI TLP to
differentiate between the various MSI messages sent upstream. The number of lower-order
bits in the Message Data field available to the user application is determined by the lesser
of the value of the Multiple Message Capable field, as set in the Vivado IDE, and the
Multiple Message Enable field, as set by system software and available as the
cfg_interrupt_mmenable[2:0] core output. The core masks any bits in
cfg_interrupt_di[7:0] which are not configured by the system software through
Multiple Message Enable.
This pseudo code shows the processing required:
// Value MSI_Vector_Num must be in range: 0 ≤ MSI_Vector_Num ≤
(2^cfg_interrupt_mmenable)-1
if (cfg_interrupt_msienable) {
// MSI Enabled
if (cfg_interrupt_mmenable > 0) { // Multi-Vector MSI Enabled
cfg_interrupt_di[7:0] = {Padding_0s, MSI_Vector_Num};
} else {
// Single-Vector MSI Enabled
cfg_interrupt_di[7:0] = Padding_0s;
}
} else {
// Legacy Interrupts Enabled
}
For example:
1. If cfg_interrupt_mmenable[2:0] == 000b, that is, 1 MSI Vector Enabled,
then cfg_interrupt_di[7:0] = 00h;
2. if cfg_interrupt_mmenable[2:0] == 101b, that is, 32 MSI Vectors Enabled,
then cfg_interrupt_di[7:0] = {{000b}, {MSI_Vector#}};
where MSI_Vector# is a 5-bit value and is allowed to be 00000b ≤ MSI_Vector# ≤ 11111b.
If Per-Vector Masking is enabled, you must first verify that the vector being signaled is not
masked in the Mask register. This is done by reading this register on the Configuration
interface (the core does not look at the Mask register).
MSI-X Mode
The core optionally supports the MSI-X Capability Structure. The MSI-X vector table and the
MSI-X Pending Bit Array need to be implemented as part of your logic, by claiming a BAR
aperture.
If the cfg_interrupt_msixenable output of the core is asserted, the user application should
compose and present the MSI-X interrupts on the transmit AXI4-Stream interface.
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Link Training: 2-Lane, 4-Lane, and 8-Lane Components
The 2-lane, 4-lane, and 8-lane core can operate at less than the maximum lane width as
required by the PCI Express Base Specification [Ref 2]. Two cases cause core to operate at
less than its specified maximum lane width, as defined in these subsections.
Link Partner Supports Fewer Lanes
When the 2-lane core is connected to a device that implements only 1 lane, the 2-lane core
trains and operates as a 1-lane device using lane 0.
When the 4-lane core is connected to a device that implements 1 lane, the 4-lane core
trains and operates as a 1-lane device using lane 0, as shown in Figure 3-69. Similarly, if the
4-lane core is connected to a 2-lane device, the core trains and operates as a 2-lane device
using lanes 0 and 1.
When the 8-lane core is connected to a device that only implements 4 lanes, it trains and
operates as a 4-lane device using lanes 0-3. Additionally, if the connected device only
implements 1 or 2 lanes, the 8-lane core trains and operates as a 1- or 2-lane device.
X-Ref Target - Figure 3-69
Upstream Device
Upstream Device
4-lane Downstream Port
Lane 0 Lane 1 Lane 2 Lane 3
1-lane Downstream Port
Lane 0 Lane 1 Lane 2 Lane 3
Note: Shaded blocks indicate
disabled lanes.
Lane 0 Lane 1 Lane 2 Lane 3
Lane 0 Lane 1 Lane 2 Lane 3
4-lane Integrated Block
4-lane Integrated Block
Figure 3-69:
Scaling of 4-Lane Endpoint Block from 4-Lane to 1-Lane Operation
Lane Becomes Faulty
If a link becomes faulty after training to the maximum lane width supported by the core and
the link partner device, the core attempts to recover and train to a lower lane width, if
available. If lane 0 becomes faulty, the link is irrecoverably lost. If any or all of lanes 1–7
become faulty, the link goes into recovery and attempts to recover the largest viable link
with whichever lanes are still operational.
For example, when using the 8-lane core, loss of lane 1 yields a recovery to 1-lane operation
on lane 0, whereas the loss of lane 6 yields a recovery to 4-lane operation on lanes 0-3.
After recovery occurs, if the failed lane(s) becomes alive again, the core does not attempt to
recover to a wider link width. The only way a wider link width can occur is if the link actually
goes down and it attempts to retrain from scratch.
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The user_clk_out clock output is a fixed frequency configured in the Vivado IDE.
user_clk_out does not shift frequencies in case of link recovery or training down.
Lane Reversal
The integrated Endpoint block supports limited lane reversal capabilities and therefore
provides flexibility in the design of the board for the link partner. The link partner can
choose to lay out the board with reversed lane numbers and the integrated Endpoint block
continues to link train successfully and operate normally. The configurations that have lane
reversal support are x8, x4 (excluding downshift modes), and x2. Downshift refers to the link
width negotiation process that occurs when link partners have different lane width
capabilities advertised. As a result of lane width negotiation, the link partners negotiate
down to the smaller of the two advertised lane widths. Table 3-47 describes the several
possible combinations including downshift modes and availability of lane reversal support.
Table 3-47:
Lane Reversal Support
Lane Number Mapping
(Endpoint Link Partner)
Endpoint Block
Advertised
Lane Width
Negotiated
Lane
Width
Endpoint
Link Partner
Lane
Reversal
Supported
x8
x8
Lane 0 ... Lane 7
Lane 7 ... Lane 0
Yes
x8
x4
Lane 0 ... Lane 3
Lane 7 ... Lane 4
No(1)
x8
x2
Lane 0 ... Lane 3
Lane 7 ... Lane 6
No(1)
x4
x4
Lane 0 ... Lane 3
Lane 3 ... Lane 0
Yes
x4
x2
Lane 0 ... Lane 1
Lane 3 ... Lane 2
No(1)
x2
x2
Lane 0 ... Lane 1
Lane 1... Lane 0
Yes
x2
x1
Lane 0 ... Lane 1
Lane 1
No(1)
Notes:
1. When the lanes are reversed in the board layout and a downshift adapter card is inserted between the Endpoint
and link partner, Lane 0 of the link partner remains unconnected (as shown by the lane mapping in Table 3-47) and
therefore does not link train.
Using the Dynamic Reconfiguration Port Interface
The Dynamic Reconfiguration Port (DRP) interface allows read and write access to the FPGA
configuration memory bits of the integrated block instantiated as part of the core. These
configuration memory bits are represented as attributes of the PCIE_2_1 library element.
The DRP interface is a standard interface found on many integrated IP blocks in Xilinx
devices. For detailed information about how the DRP interface works with the FPGA
configuration memory, see the 7 Series FPGAs Configuration User Guide (UG470) [Ref 7].
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Writing and Reading the DRP Interface
The interface is a processor-friendly synchronous interface with an address bus (drp_addr)
and separated data buses for reading (drp_do) and writing (drp_di) configuration data to
the PCIE_2_1 block. An enable signal (drp_en), a read/write signal (drp_we), and a ready/
valid signal (drp_rdy) are the control signals that implement read and write operations,
indicate operation completion, or indicate the availability of data. Figure 3-70 shows a write
cycle, and Figure 3-71 shows a read cycle.
X-Ref Target - Figure 3-70
pcie_drp_clk
pcie_drp_en
pcie_drp_we
pcie_drp_addr[8:0]
addr
pcie_drp_di[15:0]
data
pcie_drp_rdy
pcie_drp_do[15:0]
data
Figure 3-70:
DRP Interface Write Cycle
X-Ref Target - Figure 3-71
pcie_drp_clk
pcie_drp_en
pcie_drp_we
pcie_drp_addr[8:0]
addr
pcie_drp_di[15:0]
pcie_drp_rdy
pcie_drp_do[15:0]
data
Figure 3-71:
DRP Interface Read Cycle
Other Considerations for the DRP Interface
Updating attribute values through the DRP port is only supported while the core is in reset
with sys_rst_n asserted. Behavior of the core is undefined if attributes are updated
on-the-fly with sys_rst_n deasserted. Reading attributes through the DRP port is
independent of sys_rst_n.
Attributes larger than 16 bits span two drp_daddr addresses, for example BAR0[31:0]
requires two accesses to read or write the attribute. Additionally, some attributes share a
single drp_daddr address. Use a read-modify-write approach so that shared-address
attributes are not modified unintentionally.
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There are many attributes that should not be modified through DRP, because these
attributes need to be set in an aligned manner with the rest of the design. For example,
changing the memory latency attributes on the PCIE_2_1 block without changing the actual
number of pipeline registers attached to the block RAM causes a functional failure. These
attributes are included in this category:
•
DEV_CAP_MAX_PAYLOAD_SUPPORTED
•
VC0_TX_LASTPACKET
•
TL_TX_RAM_RADDR_LATENCY
•
TL_TX_RAM_RDATA_LATENCY
•
TL_TX_RAM_WRITE_LATENCY
•
VC0_RX_LIMIT
•
TL_RX_RAM_RADDR_LATENCY
•
TL_RX_RAM_RDATA_LATENCY
•
TL_RX_RAM_WRITE_LATENCY
DRP Address Map
Table 3-48 defines the DRP address map for the PCIE_2_1 library element attributes. Some
attributes span two addresses, for example, BAR0. In addition, some addresses contain
multiple attributes; for example, address 0x004 contains both AER_CAP_NEXTPTR[11:0]
and AER_CAP_ON.
Table 3-48:
DRP Address Map for PCIE_2_1 Library Element Attributes
Address
drp_daddr[8:0]
Data Bits
drp_di[15:0] or
drp_do[15:0]
AER_CAP_ECRC_CHECK_CAPABLE
0x000
[0]
AER_CAP_ECRC_GEN_CAPABLE
0x000
[1]
AER_CAP_ID[15:0]
0x001
[15:0]
AER_CAP_PERMIT_ROOTERR_UPDATE
0x002
[0]
AER_CAP_VERSION[3:0]
0x001
[4:1]
AER_BASE_PTR[11:0]
0x003
[11:0]
AER_CAP_NEXTPTR[11:0]
0x004
[11:0]
AER_CAP_ON
0x004
[12]
AER_CAP_OPTIONAL_ERR_SUPPORT[15:0]
0x005
[15:0]
AER_CAP_OPTIONAL_ERR_SUPPORT[23:16]
0x006
[7:0]
AER_CAP_MULTIHEADER
0x006
[8]
BAR0[15:0]
0x007
[15:0]
Attribute Name
7 Series Integrated Block for PCIe v3.1
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Chapter 3: Designing with the Core
Table 3-48:
DRP Address Map for PCIE_2_1 Library Element Attributes (Cont’d)
Address
drp_daddr[8:0]
Data Bits
drp_di[15:0] or
drp_do[15:0]
BAR0[31:16]
0x008
[15:0]
BAR1[15:0]
0x009
[15:0]
BAR1[31:16]
0x00a
[15:0]
BAR2[15:0]
0x00b
[15:0]
BAR2[31:16]
0x00c
[15:0]
BAR3[15:0]
0x00d
[15:0]
BAR3[31:16]
0x00e
[15:0]
BAR4[15:0]
0x00f
[15:0]
BAR4[31:16]
0x010
[15:0]
BAR5[15:0]
0x011
[15:0]
BAR5[31:16]
0x012
[15:0]
EXPANSION_ROM[15:0]
0x013
[15:0]
EXPANSION_ROM[31:16]
0x014
[15:0]
CAPABILITIES_PTR[7:0]
0x015
[7:0]
CARDBUS_CIS_POINTER[15:0]
0x016
[15:0]
CARDBUS_CIS_POINTER[31:16]
0x017
[15:0]
CLASS_CODE[15:0]
0x018
[15:0]
CLASS_CODE[23:16]
0x019
[7:0]
CMD_INTX_IMPLEMENTED
0x019
[8]
CPL_TIMEOUT_DISABLE_SUPPORTED
0x019
[9]
CPL_TIMEOUT_RANGES_SUPPORTED[3:0]
0x019
[13:10]
DEV_CAP2_ARI_FORWARDING_SUPPORTED
0x019
[14]
DEV_CAP2_ATOMICOP_ROUTING_SUPPORTED
0x019
[15]
DEV_CAP2_ATOMICOP32_COMPLETER_SUPPORTED
0x01a
[0]
DEV_CAP2_ATOMICOP64_COMPLETER_SUPPORTED
0x01a
[1]
DEV_CAP2_CAS128_COMPLETER_SUPPORTED
0x01a
[2]
DEV_CAP2_NO_RO_ENABLED_PRPR_PASSING
0x01a
[3]
DEV_CAP2_LTR_MECHANISM_SUPPORTED
0x01a
[4]
DEV_CAP2_TPH_COMPLETER_SUPPORTED[1:0]
0x01a
[6:5]
DEV_CAP2_EXTENDED_FMT_FIELD_SUPPORTED
0x01a
[7]
DEV_CAP2_ENDEND_TLP_PREFIX_SUPPORTED
0x01a
[8]
DEV_CAP2_MAX_ENDEND_TLP_PREFIXES[1:0]
0x01a
[10:9]
ENDEND_TLP_PREFIX_FORWARDING_SUPPORTED
0x01a
[11]
Attribute Name
7 Series Integrated Block for PCIe v3.1
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Chapter 3: Designing with the Core
Table 3-48:
DRP Address Map for PCIE_2_1 Library Element Attributes (Cont’d)
Address
drp_daddr[8:0]
Data Bits
drp_di[15:0] or
drp_do[15:0]
DEV_CAP_ENABLE_SLOT_PWR_LIMIT_SCALE
0x01a
[12]
DEV_CAP_ENABLE_SLOT_PWR_LIMIT_VALUE
0x01a
[13]
DEV_CAP_ENDPOINT_L0S_LATENCY[2:0]
0x01b
[2:0]
DEV_CAP_ENDPOINT_L1_LATENCY[2:0]
0x01b
[5:3]
DEV_CAP_EXT_TAG_SUPPORTED
0x01b
[6]
DEV_CAP_FUNCTION_LEVEL_RESET_CAPABLE
0x01b
[7]
DEV_CAP_MAX_PAYLOAD_SUPPORTED[2:0]
0x01b
[10:8]
DEV_CAP_PHANTOM_FUNCTIONS_SUPPORT[1:0]
0x01b
[12:11]
DEV_CAP_ROLE_BASED_ERROR
0x01b
[13]
DEV_CAP_RSVD_14_12[2:0]
0x01c
[2:0]
DEV_CAP_RSVD_17_16[1:0]
0x01c
[4:3]
DEV_CAP_RSVD_31_29[2:0]
0x01c
[7:5]
DEV_CONTROL_AUX_POWER_SUPPORTED
0x01c
[8]
DEV_CONTROL_EXT_TAG_DEFAULT
0x01c
[9]
DSN_BASE_PTR[11:0]
0x01d
[11:0]
DSN_CAP_ID[15:0]
0x01e
[15:0]
DSN_CAP_NEXTPTR[11:0]
0x01f
[11:0]
DSN_CAP_ON
0x01f
[12]
DSN_CAP_VERSION[3:0]
0x020
[3:0]
EXT_CFG_CAP_PTR[5:0]
0x020
[9:4]
EXT_CFG_XP_CAP_PTR[9:0]
0x021
[9:0]
HEADER_TYPE[7:0]
0x022
[7:0]
INTERRUPT_PIN[7:0]
0x022
[15:8]
INTERRUPT_STAT_AUTO
0x023
[0]
IS_SWITCH
0x023
[1]
LAST_CONFIG_DWORD[9:0]
0x023
[11:2]
LINK_CAP_ASPM_SUPPORT[1:0]
0x023
[13:12]
LINK_CAP_CLOCK_POWER_MANAGEMENT
0x023
[14]
LINK_CAP_DLL_LINK_ACTIVE_REPORTING_CAP
0x023
[15]
LINK_CAP_L0S_EXIT_LATENCY_COMCLK_GEN1[2:0]
0x024
[2:0]
LINK_CAP_L0S_EXIT_LATENCY_COMCLK_GEN2[2:0]
0x024
[5:3]
LINK_CAP_L0S_EXIT_LATENCY_GEN1[2:0]
0x024
[8:6]
LINK_CAP_L0S_EXIT_LATENCY_GEN2[2:0]
0x024
[11:9]
Attribute Name
7 Series Integrated Block for PCIe v3.1
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Chapter 3: Designing with the Core
Table 3-48:
DRP Address Map for PCIE_2_1 Library Element Attributes (Cont’d)
Address
drp_daddr[8:0]
Data Bits
drp_di[15:0] or
drp_do[15:0]
LINK_CAP_L1_EXIT_LATENCY_COMCLK_GEN1[2:0]
0x024
[14:12]
LINK_CAP_L1_EXIT_LATENCY_COMCLK_GEN2[2:0]
0x025
[2:0]
LINK_CAP_L1_EXIT_LATENCY_GEN1[2:0]
0x025
[5:3]
LINK_CAP_L1_EXIT_LATENCY_GEN2[2:0]
0x025
[8:6]
LINK_CAP_LINK_BANDWIDTH_NOTIFICATION_CAP
0x025
[9]
LINK_CAP_MAX_LINK_SPEED[3:0]
0x025
[13:10]
LINK_CAP_ASPM_OPTIONALITY
0x025
[14]
LINK_CAP_RSVD_23
0x025
[15]
LINK_CAP_SURPRISE_DOWN_ERROR_CAPABLE
0x026
[0]
LINK_CONTROL_RCB
0x026
[1]
LINK_CTRL2_DEEMPHASIS
0x026
[2]
LINK_CTRL2_HW_AUTONOMOUS_SPEED_DISABLE
0x026
[3]
LINK_CTRL2_TARGET_LINK_SPEED[3:0]
0x026
[7:4]
LINK_STATUS_SLOT_CLOCK_CONFIG
0x026
[8]
MPS_FORCE
0x026
[9]
MSI_BASE_PTR[7:0]
0x027
[7:0]
MSI_CAP_64_BIT_ADDR_CAPABLE
0x027
[8]
MSI_CAP_ID[7:0]
0x028
[7:0]
MSI_CAP_MULTIMSG_EXTENSION
0x028
[8]
MSI_CAP_MULTIMSGCAP[2:0]
0x028
[11:9]
MSI_CAP_NEXTPTR[7:0]
0x029
[7:0]
MSI_CAP_ON
0x029
[8]
MSI_CAP_PER_VECTOR_MASKING_CAPABLE
0x029
[9]
MSIX_BASE_PTR[7:0]
0x02a
[7:0]
MSIX_CAP_ID[7:0]
0x02a
[15:8]
MSIX_CAP_NEXTPTR[7:0]
0x02b
[7:0]
MSIX_CAP_ON
0x02b
[8]
MSIX_CAP_PBA_BIR[2:0]
0x02b
[11:9]
MSIX_CAP_PBA_OFFSET[15:0]
0x02c
[15:0]
MSIX_CAP_PBA_OFFSET[28:16]
0x02d
[12:0]
MSIX_CAP_TABLE_BIR[2:0]
0x02d
[15:13]
MSIX_CAP_TABLE_OFFSET[15:0]
0x02e
[15:0]
MSIX_CAP_TABLE_OFFSET[28:16]
0x02f
[12:0]
Attribute Name
7 Series Integrated Block for PCIe v3.1
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147
Chapter 3: Designing with the Core
Table 3-48:
DRP Address Map for PCIE_2_1 Library Element Attributes (Cont’d)
Address
drp_daddr[8:0]
Data Bits
drp_di[15:0] or
drp_do[15:0]
MSIX_CAP_TABLE_SIZE[10:0]
0x030
[10:0]
PCIE_BASE_PTR[7:0]
0x031
[7:0]
PCIE_CAP_CAPABILITY_ID[7:0]
0x031
[15:8]
PCIE_CAP_CAPABILITY_VERSION[3:0]
0x032
[3:0]
PCIE_CAP_DEVICE_PORT_TYPE[3:0]
0x032
[7:4]
PCIE_CAP_NEXTPTR[7:0]
0x032
[15:8]
PCIE_CAP_ON
0x033
[0]
PCIE_CAP_RSVD_15_14[1:0]
0x033
[2:1]
PCIE_CAP_SLOT_IMPLEMENTED
0x033
[3]
PCIE_REVISION[3:0]
0x033
[7:4]
PM_BASE_PTR[7:0]
0x033
[15:8]
PM_CAP_AUXCURRENT[2:0]
0x034
[2:0]
PM_CAP_D1SUPPORT
0x034
[3]
PM_CAP_D2SUPPORT
0x034
[4]
PM_CAP_DSI
0x034
[5]
PM_CAP_ID[7:0]
0x034
[13:6]
PM_CAP_NEXTPTR[7:0]
0x035
[7:0]
PM_CAP_ON
0x035
[8]
PM_CAP_PME_CLOCK
0x035
[9]
PM_CAP_PMESUPPORT[4:0]
0x035
[14:10]
PM_CAP_RSVD_04
0x035
[15]
PM_CAP_VERSION[2:0]
0x036
[2:0]
PM_CSR_B2B3
0x036
[3]
PM_CSR_BPCCEN
0x036
[4]
PM_CSR_NOSOFTRST
0x036
[5]
PM_DATA_SCALE0[1:0]
0x036
[7:6]
PM_DATA_SCALE1[1:0]
0x036
[9:8]
PM_DATA_SCALE2[1:0]
0x036
[11:10]
PM_DATA_SCALE3[1:0]
0x036
[13:12]
PM_DATA_SCALE4[1:0]
0x036
[15:14]
PM_DATA_SCALE5[1:0]
0x037
[1:0]
PM_DATA_SCALE6[1:0]
0x037
[3:2]
PM_DATA_SCALE7[1:0]
0x037
[5:4]
Attribute Name
7 Series Integrated Block for PCIe v3.1
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Chapter 3: Designing with the Core
Table 3-48:
DRP Address Map for PCIE_2_1 Library Element Attributes (Cont’d)
Address
drp_daddr[8:0]
Data Bits
drp_di[15:0] or
drp_do[15:0]
PM_DATA0[7:0]
0x037
[13:6]
PM_DATA1[7:0]
0x038
[7:0]
PM_DATA2[7:0]
0x038
[15:8]
PM_DATA3[7:0]
0x039
[7:0]
PM_DATA4[7:0]
0x039
[15:8]
PM_DATA5[7:0]
0x03a
[7:0]
PM_DATA6[7:0]
0x03a
[15:8]
PM_DATA7[7:0]
0x03b
[7:0]
RBAR_BASE_PTR[11:0]
0x03c
[11:0]
RBAR_CAP_NEXTPTR[11:0]
0x03d
[11:0]
RBAR_CAP_ON
0x03d
[12]
RBAR_CAP_ID[15:0]
0x03e
[15:0]
RBAR_CAP_VERSION[3:0]
0x03f
[3:0]
RBAR_NUM[2:0]
0x03f
[6:4]
RBAR_CAP_SUP0[15:0]
0x040
[15:0]
RBAR_CAP_SUP0[31:16]
0x041
[15:0]
RBAR_CAP_SUP1[15:0]
0x042
[15:0]
RBAR_CAP_SUP1[31:16]
0x043
[15:0]
RBAR_CAP_SUP2[15:0]
0x044
[15:0]
RBAR_CAP_SUP2[31:16]
0x045
[15:0]
RBAR_CAP_SUP3[15:0]
0x046
[15:0]
RBAR_CAP_SUP3[31:16]
0x047
[15:0]
RBAR_CAP_SUP4[15:0]
0x048
[15:0]
RBAR_CAP_SUP4[31:16]
0x049
[15:0]
RBAR_CAP_SUP5[15:0]
0x04a
[15:0]
RBAR_CAP_SUP5[31:16]
0x04b
[15:0]
RBAR_CAP_INDEX0[2:0]
0x04c
[2:0]
RBAR_CAP_INDEX1[2:0]
0x04c
[5:3]
RBAR_CAP_INDEX2[2:0]
0x04c
[8:6]
RBAR_CAP_INDEX3[2:0]
0x04c
[11:9]
RBAR_CAP_INDEX4[2:0]
0x04c
[14:12]
RBAR_CAP_INDEX5[2:0]
0x04d
[2:0]
RBAR_CAP_CONTROL_ENCODEDBAR0[4:0]
0x04d
[7:3]
Attribute Name
7 Series Integrated Block for PCIe v3.1
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149
Chapter 3: Designing with the Core
Table 3-48:
DRP Address Map for PCIE_2_1 Library Element Attributes (Cont’d)
Address
drp_daddr[8:0]
Data Bits
drp_di[15:0] or
drp_do[15:0]
RBAR_CAP_CONTROL_ENCODEDBAR1[4:0]
0x04d
[12:8]
RBAR_CAP_CONTROL_ENCODEDBAR2[4:0]
0x04e
[4:0]
RBAR_CAP_CONTROL_ENCODEDBAR3[4:0]
0x04e
[9:5]
RBAR_CAP_CONTROL_ENCODEDBAR4[4:0]
0x04e
[14:10]
RBAR_CAP_CONTROL_ENCODEDBAR5[4:0]
0x04f
[4:0]
ROOT_CAP_CRS_SW_VISIBILITY
0x04f
[5]
SELECT_DLL_IF
0x04f
[6]
SLOT_CAP_ATT_BUTTON_PRESENT
0x04f
[7]
SLOT_CAP_ATT_INDICATOR_PRESENT
0x04f
[8]
SLOT_CAP_ELEC_INTERLOCK_PRESENT
0x04f
[9]
SLOT_CAP_HOTPLUG_CAPABLE
0x04f
[10]
SLOT_CAP_HOTPLUG_SURPRISE
0x04f
[11]
SLOT_CAP_MRL_SENSOR_PRESENT
0x04f
[12]
SLOT_CAP_NO_CMD_COMPLETED_SUPPORT
0x04f
[13]
SLOT_CAP_PHYSICAL_SLOT_NUM[12:0]
0x050
[12:0]
SLOT_CAP_POWER_CONTROLLER_PRESENT
0x050
[13]
SLOT_CAP_POWER_INDICATOR_PRESENT
0x050
[14]
SLOT_CAP_SLOT_POWER_LIMIT_SCALE[1:0]
0x051
[1:0]
SLOT_CAP_SLOT_POWER_LIMIT_VALUE[7:0]
0x051
[9:2]
SSL_MESSAGE_AUTO
0x051
[10]
VC_BASE_PTR[11:0]
0x052
[11:0]
VC_CAP_NEXTPTR[11:0]
0x053
[11:0]
VC_CAP_ON
0x053
[12]
VC_CAP_ID[15:0]
0x054
[15:0]
VC_CAP_REJECT_SNOOP_TRANSACTIONS
0x055
[0]
VSEC_BASE_PTR[11:0]
0x055
[12:1]
VSEC_CAP_HDR_ID[15:0]
0x056
[15:0]
VSEC_CAP_HDR_LENGTH[11:0]
0x057
[11:0]
VSEC_CAP_HDR_REVISION[3:0]
0x057
[15:12]
VSEC_CAP_ID[15:0]
0x058
[15:0]
VSEC_CAP_IS_LINK_VISIBLE
0x059
[0]
VSEC_CAP_NEXTPTR[11:0]
0x059
[12:1]
VSEC_CAP_ON
0x059
[13]
Attribute Name
7 Series Integrated Block for PCIe v3.1
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150
Chapter 3: Designing with the Core
Table 3-48:
DRP Address Map for PCIE_2_1 Library Element Attributes (Cont’d)
Address
drp_daddr[8:0]
Data Bits
drp_di[15:0] or
drp_do[15:0]
VSEC_CAP_VERSION[3:0]
0x05a
[3:0]
USER_CLK_FREQ[2:0]
0x05a
[6:4]
CRM_MODULE_RSTS[6:0]
0x05a
[13:7]
LL_ACK_TIMEOUT[14:0]
0x05b
[14:0]
LL_ACK_TIMEOUT_EN
0x05b
[15]
LL_ACK_TIMEOUT_FUNC[1:0]
0x05c
[1:0]
LL_REPLAY_TIMEOUT[14:0]
0x05d
[14:0]
LL_REPLAY_TIMEOUT_EN
0x05d
[15]
LL_REPLAY_TIMEOUT_FUNC[1:0]
0x05e
[1:0]
PM_ASPML0S_TIMEOUT[14:0]
0x05f
[14:0]
PM_ASPML0S_TIMEOUT_EN
0x05f
[15]
PM_ASPML0S_TIMEOUT_FUNC[1:0]
0x060
[1:0]
PM_ASPM_FASTEXIT
0x060
[2]
DISABLE_LANE_REVERSAL
0x060
[3]
DISABLE_SCRAMBLING
0x060
[4]
ENTER_RVRY_EI_L0
0x060
[5]
INFER_EI[4:0]
0x060
[10:6]
LINK_CAP_MAX_LINK_WIDTH[5:0]
0x061
[5:0]
LTSSM_MAX_LINK_WIDTH[5:0]
0x061
[11:6]
N_FTS_COMCLK_GEN1[7:0]
0x062
[7:0]
N_FTS_COMCLK_GEN2[7:0]
0x062
[15:8]
N_FTS_GEN1[7:0]
0x063
[7:0]
N_FTS_GEN2[7:0]
0x063
[15:8]
ALLOW_X8_GEN2
0x064
[0]
PL_AUTO_CONFIG[2:0]
0x064
[3:1]
PL_FAST_TRAIN
0x064
[4]
UPCONFIG_CAPABLE
0x064
[5]
UPSTREAM_FACING
0x064
[6]
EXIT_LOOPBACK_ON_EI
0x064
[7]
DNSTREAM_LINK_NUM[7:0]
0x064
[15:8]
DISABLE_ASPM_L1_TIMER
0x065
[0]
DISABLE_BAR_FILTERING
0x065
[1]
DISABLE_ID_CHECK
0x065
[2]
Attribute Name
7 Series Integrated Block for PCIe v3.1
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151
Chapter 3: Designing with the Core
Table 3-48:
DRP Address Map for PCIE_2_1 Library Element Attributes (Cont’d)
Address
drp_daddr[8:0]
Data Bits
drp_di[15:0] or
drp_do[15:0]
DISABLE_RX_TC_FILTER
0x065
[3]
DISABLE_RX_POISONED_RESP
0x065
[4]
ENABLE_MSG_ROUTE[10:0]
0x065
[15:5]
ENABLE_RX_TD_ECRC_TRIM
0x066
[0]
TL_RX_RAM_RADDR_LATENCY
0x066
[1]
TL_RX_RAM_RDATA_LATENCY[1:0]
0x066
[3:2]
TL_RX_RAM_WRITE_LATENCY
0x066
[4]
TL_TFC_DISABLE
0x066
[5]
TL_TX_CHECKS_DISABLE
0x066
[6]
TL_RBYPASS
0x066
[7]
DISABLE_PPM_FILTER
0x066
[8]
DISABLE_LOCKED_FILTER
0x066
[9]
USE_RID_PINS
0x066
[10]
DISABLE_ERR_MSG
0x066
[11]
PM_MF
0x066
[12]
TL_TX_RAM_RADDR_LATENCY
0x066
[13]
TL_TX_RAM_RDATA_LATENCY[1:0]
0x066
[15:14]
TL_TX_RAM_WRITE_LATENCY
0x067
[0]
VC_CAP_VERSION[3:0]
0x067
[4:1]
VC0_CPL_INFINITE
0x067
[5]
VC0_RX_RAM_LIMIT[12:0]
0x068
[12:0]
VC0_TOTAL_CREDITS_CD[10:0]
0x069
[10:0]
VC0_TOTAL_CREDITS_CH[6:0]
0x06a
[6:0]
VC0_TOTAL_CREDITS_NPH[6:0]
0x06a
[13:7]
VC0_TOTAL_CREDITS_NPD[10:0]
0x06b
[10:0]
VC0_TOTAL_CREDITS_PD[10:0]
0x06c
[10:0]
VC0_TOTAL_CREDITS_PH[6:0]
0x06d
[6:0]
VC0_TX_LASTPACKET[4:0]
0x06d
[11:7]
RECRC_CHK[1:0]
0x06d
[13:12]
RECRC_CHK_TRIM
0x06d
[14]
TECRC_EP_INV
0x06d
[15]
CFG_ECRC_ERR_CPLSTAT[1:0]
0x06e
[1:0]
UR_INV_REQ
0x06e
[2]
Attribute Name
7 Series Integrated Block for PCIe v3.1
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152
Chapter 3: Designing with the Core
Table 3-48:
DRP Address Map for PCIE_2_1 Library Element Attributes (Cont’d)
Address
drp_daddr[8:0]
Data Bits
drp_di[15:0] or
drp_do[15:0]
UR_PRS_RESPONSE
0x06e
[3]
UR_ATOMIC
0x06e
[4]
UR_CFG1
0x06e
[5]
TRN_DW
0x06e
[6]
TRN_NP_FC
0x06e
[7]
USER_CLK2_DIV2
0x06e
[8]
RP_AUTO_SPD[1:0]
0x06e
[10:9]
RP_AUTO_SPD_LOOPCNT[4:0]
0x06e
[15:11]
TEST_MODE_PIN_CHAR
0x06f
[0]
SPARE_BIT0
0x06f
[1]
SPARE_BIT1
0x06f
[2]
SPARE_BIT2
0x06f
[3]
SPARE_BIT3
0x06f
[4]
SPARE_BIT4
0x06f
[5]
SPARE_BIT5
0x06f
[6]
SPARE_BIT6
0x06f
[7]
SPARE_BIT7
0x06f
[8]
SPARE_BIT8
0x06f
[9]
SPARE_BYTE0[7:0]
0x070
[7:0]
SPARE_BYTE1[7:0]
0x070
[15:8]
SPARE_BYTE2[7:0]
0x071
[7:0]
SPARE_BYTE3[7:0]
0x071
[15:8]
SPARE_WORD0[15:0]
0x072
[15:0]
SPARE_WORD0[31:16]
0x073
[15:0]
SPARE_WORD1[15:0]
0x074
[15:0]
SPARE_WORD1[31:16]
0x075
[15:0]
SPARE_WORD2[15:0]
0x076
[15:0]
SPARE_WORD2[31:16]
0x077
[15:0]
SPARE_WORD3[15:0]
0x078
[15:0]
SPARE_WORD3[31:16]
0x079
[15:0]
Attribute Name
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Tandem Configuration
The 7 Series Gen2 Integrated Block for PCIe solution provides two alternative configuration
methods to meet the time requirements indicated within the PCI Express Specification. The
PCI Express Specification states that PERST# must deassert 100 ms after the power good of
the systems has occurred, and a PCI Express port must be ready to link train no more than
20ms after PERST# has deasserted. This is commonly referred to as the 100 ms boot time
requirement. The two alternative methods for configuration are referred to as Tandem
PROM and Tandem PCI Express (PCIe). These solutions have been explicitly designed for this
specific goal. If other configuration flexibility is needed, such as dynamic field updates of
the user application, general Partial Reconfiguration should be used instead of Tandem
Configuration.
Both Tandem PROM and Tandem PCIe implement a two stage configuration methodology.
In Tandem PROM and Tandem PCIe, the first stage configuration memory cells that are
critical to PCI Express operation are loaded through a local PROM. When these cells have
been loaded, an FPGA start-up command is sent at the end of the first stage bitstream to
the FPGA configuration controller. The partially configured FPGA then becomes active with
the first-stage bitstream contents. The first stage containing a fully functional PCI Express
port responds to traffic received during PCI Express enumeration while the second stage is
loaded into the FPGA. Included inside the first stage bitstream are the PCI Express
integrated block, Gigabit Transceivers, block RAM, clocking resources, FPGA logic, and
routing resources required to make the entire PCI Express port functional. The second stage
consists of the user-specific application and the remaining clocking and I/O resources,
which is basically the rest of the FPGA design. The mechanism for loading the second stage
bitstream differs between Tandem PROM and Tandem PCIe.
Supported Devices
The 7 Series Gen2 Integrated Block for PCIe core and Vivado tool flow support
implementations targeting Xilinx reference boards and specific part/package combinations.
For the Vivado Design Suite 2015.2 release, Tandem Configuration is production for specific
devices and packages only. Tandem Configuration supports the configurations found in
Table 3-49.
Table 3-49:
Tandem PROM/PCIe Supported Configurations
HDL
Verilog Only
PCIe Configuration
All configurations (max: X8Gen2)
KC705 Evaluation Board for Kintex®-7 FPGA
Xilinx Reference Board Support VC707 Evaluation Board for Virtex®-7 FPGA
ZC706 Evaluation Board for Zynq® SOC
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Table 3-49:
Tandem PROM/PCIe Supported Configurations (Cont’d)
HDL
Verilog Only
Supported Part/Package Combinations:
Device Support
Part
Package
PCIe Location
Status
XC7K160T
All
All
Production
XC7K325T
All
All
Production
XC7K410T
All
All
Production
XC7K420T
All
All
Production
XC7VX485T
All
All (X1Y0
recommended)
Production
XC7Z030
All
All
Production
XC7Z045
All
All
Production
XC7Z100
All
All
Production
Note: Support for Zynq® SoC devices is limited to the Tandem PROM variant. The Tandem PCIe
variant is not offered; similar benefits can be achieved by splitting the two stage bitstreams and
delivering both over the PS to the PCAP. This solution avoids the additional complexity of including
the ICAP in the PL design.
Overview of Tandem Tool Flow
Tandem PROM and Tandem PCIe solutions are only supported in the Vivado Design Suite.
The tool flow for both solutions is as follows:
1. Customize the core: select a supported device from Table 3-49 and select Tandem
PROM or Tandem PCIe for the Tandem Configuration option.
2. Generate the core.
3. Open the example project, and implement the example design.
4. Use the IP and XDC from the example project in your project, and instantiate the core.
5. Synthesize and implement your design.
6. Generate bit and then prom files.
As part of the Tandem flows, certain elements located outside of the PCIe core logic must
also be brought up as part of the first stage bitstream. This is implemented using a Tcl file
which is generated during core generation. When running through the project based flow,
the Tcl is invoked automatically prior to design optimization (opt_design). This file is
called build_stage1.tcl and can be found under the IP sources tree in the example
design:
<project_name>.srcs\sources_1\ip\<core_name>\source
It is important that the clocking and reset structure remain the same even if the hierarchy
level in the design changes. The Tcl script searches for and finds the appropriate clock and
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reset nets, and adds them to the first stage boot logic if the structure is not modified from
what is delivered in the example design.
Prior to bitstream generation, a Tcl file named create_bitstreams.tcl is invoked to set
specific bitstream options required for the Tandem flow. The create_bitstreams.tcl
should not be modified as it is overwritten if the PCIe core is regenerated.
IMPORTANT: Starting with 2013.3, the create_bitstreams.tcl and build_stage1.tcl should
not be modified. The create_bitstreams.tcl file contains examples of how to configure both SPI
and BPI configuration options, but these examples should be placed in a script or design constraint file,
and run before bitstream creation.
When the example design is created, an example XDC file is generated with certain
constraints that need to be copied over into your XDC file for your specific project. The
specific constraints are documented in the example design XDC file. In addition, this
example design XDC file contains examples of how to set options for flash devices, such as
BPI and SPI.
Tandem Configuration is supported only for the AXI4-Stream version of the core, and must
be generated through the IP Catalog.
Tandem PROM
The Tandem PROM solution splits a bitstream into two parts and both of those parts are
loaded from an onboard local configuration memory (typically, any PROM or flash device).
The first part of the bitstream configures the PCI Express portion of the design and the
second part configures the rest of the FPGA. Although the design is viewed to have two
unique stages, shown in Figure 3-72, the resulting BIT file is monolithic and contains both
the first and second stages.
4ANDEM02/-
3TAGE0#)E
&IRST3TAGE
&IRST3TAGE
3TAGE5SER
3ECOND3TAGE !PPLICATION
)NTEGRATED"LOCK
FOR0#)E
X-Ref Target - Figure 3-72
5SER
!PPLICATION 8
Figure 3-72:
Tandem PROM Bitstream Load Steps
Tandem PROM KC705 Example Tool Flow
This section demonstrates the Vivado tool flow from start to finish when targeting the
KC705 reference board. Paths and pointers within this flow description assume the default
component name “pcie_7x_0” is used.
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1. Create a new Vivado project, and select a supported part/package shown in Table 3-49.
2. In the Vivado IP catalog, expand Standard Bus Interfaces > PCI Express, and
double-click 7 Series Integrated Block for PCI Express to open the Customize IP
dialog box.
X-Ref Target - Figure 3-73
Figure 3-73:
Vivado IP Catalog
3. In the Customize IP dialog box Basic tab, ensure the following options are selected:
°
Silicon Revision: GES and Production
Note: Tandem Configuration is only supported on General Engineering Sample and
Production silicon.
°
Tandem Configuration: Tandem PROM
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X-Ref Target - Figure 3-74
Figure 3-74:
Tandem PROM
4. Perform additional PCIe customizations, and click OK to generate the core.
5. Click Generate when asked about which Output Products to create.
6. In the Sources tab, right-click the core, and select Open IP Example Design.
A new instance of Vivado is created and the example design is automatically loaded into
the Vivado IDE.
7. Run Synthesis and Implementation.
Click Run Implementation in the Flow Navigator. Select OK to run through synthesis
first. The design runs through the complete tool flow and the result is a fully routed
design that supports Tandem PROM.
8. Setup PROM or Flash settings.
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Set the appropriate settings to correctly generate a bitstream for a PROM or Flash
device. For more information, see Programming the Device, page 171.
9. Generate the bitstream.
After Synthesis and Implementation is complete, click Generate Bitstream in the Flow
Navigator. A bitstream supporting Tandem configuration is generated in the runs
directory, for example: ./pcie_7x_0_example.runs/impl/
xilinx_pcie_2_2_ep_7x.bit.
Note: You have the option of creating the first and second stage bitstreams independently. This
flow allows you to control the loading of each stage through the JTAG interface for testing
purposes. Here are the commands required to generate the bitstreams. This command can be
seen in the create_bitstreams.tcl file, and can be added to a Tcl script file and included as
a tcl.pre file for the Write Bitstream step. This can be done through the Bitstream Settings
dialog box under the “tcl.pre” setting.
set_property bitstream.config.tandem_writebitstream separate [current_design]
The resulting bit files created are named xilinx_pcie_2_2_ep_7x_tandem1.bit
and xilinx_pcie_2_2_ep_7x_tandem2.bit.
10. Generate the PROM file.
Run the following command in the Vivado Tcl Console to create a PROM file supported
on the KC705 development board.
promgen -w -p mcs -spi -u 0x0 xilinx_pcie_2_2_ep_7x.bit
Tandem PROM Summary
By using Tandem PROM, you can significantly reduce the amount of time required to
configure the PCIe portion of a 7 series FPGA design. The 7 Series Gen2 Integrated Block for
PCIe core manages many design details, allowing you to focus your attention on the user
application.
Tandem PCIe
Tandem PCIe is similar to Tandem PROM. In the f irst stage bitstream, only the conf iguration
memory cells that are necessary for PCI Express operation are loaded from the PROM. After
the first stage bitstream is loaded, the PCI Express port is capable of responding to
enumeration traffic. Subsequently, the second stage of the bitstream is transmitted through
the PCI Express link . Figure 3-75 illustrates the bitstream loading flow.
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X-Ref Target - Figure 3-75
0#)ELINK
5SER!PPLICATION
#&'0/24
)NITIAL0#)E
)NTERFACE
&0'!3TARTUP
02/-
SERIES&0'!
Figure 3-75:
8
Tandem PCIe Bitstream Load Steps
Tandem PCIe is similar to the standard model used today in terms of tool flow and bitstream
generation. Two bitstreams are produced when running bitstream generation. One BIT file
representing the first stage is downloaded into the PROM while the other BIT file
representing the user application (the second stage) configures the remainder of the FPGA
using the Internal Configuration Access Port (ICAP).
Note: Field updates of the second stage bitstream, that is, multiple user application images for an
unchanging first stage bitstream, require partial reconfiguration, which is not a supported flow for 7
series and Zynq devices. If this capability is required, a standard partial reconfiguration flow, utilizing
a black box configuration and compression, should be used.
Tandem PCIe KC705 Example Tool Flow
This section demonstrates the Vivado tool flow from start to finish when targeting the
KC705 reference board. Paths and pointers within this flow description assume the default
component name pcie_7x_0 is used.
1. When creating a new Vivado project, select a supported part/package shown in
Table 3-49.
2. In the Vivado IP catalog, expand Standard Bus Interfaces > PCI Express, and
double-click 7 Series Integrated Block for PCI Express to open the Customize IP
dialog box.
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X-Ref Target - Figure 3-76
Figure 3-76:
Vivado IP Catalog
3. In the Customize IP dialog box Basic tab, ensure the following options are selected:
°
Silicon Revision: GES and Production
Note: Tandem Configuration is only supported on General Engineering Sample and
Production silicon.
°
Tandem Configuration: Tandem PCIe
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X-Ref Target - Figure 3-77
Figure 3-77:
Tandem PCIe
4. Select the correct Tandem PCIe memory aperture in the BAR tab:
°
Select BAR0
Note: The Fast PCIe Configuration (FPC) module assumes the second stage bitstream is
received on BAR0.
°
Size Unit: 128 Megabytes Memory
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X-Ref Target - Figure 3-78
Figure 3-78:
BARs
5. The example design software attaches to the device through the Vendor ID and Device
ID. The Vendor ID must be 16'h10EE and the Device ID must be 16'h7024.
In the ID tab, set:
°
Vendor ID: 10EE
°
Device ID: 7024
Note: An alternative solution is the Vendor ID and Device ID can be changed, and the driver and
host PC software updated to match the new values.
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X-Ref Target - Figure 3-79
Figure 3-79:
IDs
6. Perform additional PCIe customizations, and select OK to generate the core.
After core generation, the core hierarchy is available in the Sources tab in the Vivado
IDE.
7. In the Sources tab, right-click the core, and select Open IP Example Design.
A new instance of Vivado is created and the example design project automatically loads
in the Vivado IDE.
8. Run Synthesis and Implementation.
Click Run Implementation in the Flow Navigator. Select OK to run through synthesis
first. The design runs through the complete tool flow, and the end result is a fully routed
design supporting Tandem PCIe.
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9. Setup PROM or Flash settings.
Set the appropriate settings to correctly generate a bitstream for a PROM or Flash
device. For more information, see Programming the Device, page 171.
10. Generate the bitstream.
After Synthesis and Implementation are complete, click Generate Bitstream in the Flow
Navigator. The following four files are created and placed in the runs directory:
xilinx_pcie_2_2_ep_7x_tandem1.bit|
xilinx_pcie_2_2_ep_7x_tandem2.bit|
xilinx_pcie_2_2_ep_7x_tandem1.bin|
xilinx_pcie_2_2_ep_7x_tandem2.bin
The .bit files allow you to control the loading of each stage through the JTAG
interface. The second stage .bin file is 32-bit word aligned and should be used to load
the second stage configuration through the PCIe interface.
11. Generate the PROM file for the first stage.
Run the following command in the Vivado Tcl Console to create a PROM file supported
on the KC705 development board.
promgen -w -p mcs -spi -u 0x0 xilinx_pcie_2_2_ep_7x_tandem1.bit
Loading The Second Stage Through PCI Express
An example kernel mode driver and user space application is provided with the IP. For
information on retrieving the software and documentation, see AR 51950.
Tandem PCIe Summary
By using Tandem PCIe, you can significantly reduce the amount of time required for
configuration of the PCIe portion of a 7 series design, and can reduce the bitstream flash
storage requirements. The 7 Series Gen2 Integrated Block for PCIe core manages many
design details, allowing you to focus your attention on the user application.
Using Tandem With a User Hardware Design
There are two methods available to apply the Tandem flow to a user design. The first
method is to use the example design that comes with the core. The second method is to
import the PCIe IP into an existing design and change the hierarchy of the design if
required.
Regardless of which method you use, the PCIe example design should be created to get the
example clocking structure, timing constraints, and physical block (Pblock) constraints
needed for the Tandem solution.
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Method 1 – Using the Existing PCI Express Example Design
This is the simplest method in terms of what must be done with the PCI Express core, but
might not be feasible for all users. If this approach meets your design structure needs,
follow these steps.
1. Create the example design.
Generate the example design as described in the Tandem PROM KC705 Example Tool
Flow and Tandem PCIe KC705 Example Tool Flow.
2. Insert the user application.
Replace the PIO example design with the user design. It is recommended that the global
and top-level elements, such as I/O and global clocking, be inserted in the top-level
design.
3. Copy the appropriate SPI or BPI settings from the create_bitstream.tcl file and
paste them in a new Tcl file.
Update the Vivado settings to run this Tcl file before the bitstream is generated.
4. Implement the design as normal.
Method 2 – Migrating the PCIe Design into a New Vivado Project
In cases where it is not possible to use method one above, the following steps should be
followed to use the PCIe core and the desired Tandem flow (PROM or PCIe) in a new project.
The example project has many of the required RTL and scripts that must be migrated into
the user design.
1. Create the example design.
Generate the example design as described in the Tandem PROM KC705 Example Tool
Flow and Tandem PCIe KC705 Example Tool Flow.
2. Migrate the clock module.
If the Include Shared Logic (Clocking) in the example design option is set in the
Shared Logic tab during core generation, then the pipe_clock_i clock module is
instantiated in the top level of the example design. This clock module should be
migrated to the user design to provide the necessary PCIe clocks.
Note: These clocks can be used in other parts of the user design if desired.
3. Migrate the top-level constraint.
The example Xilinx design constraints (XDC) file contains timing constraints, location
constraints and Pblock constraints for the PCIe core. All of these constraints (other than
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the I/O location and I/O standard constraints) need to be migrated to the user design.
Several of the constraints contain hierarchical references that require updating if the
hierarchy of the design is different than the example design.
4. Migrate the top-level Pblock constraint.
The following constraint is easy to miss so it is called out specifically in this step. The
Pblock constraint should point to the top level of the PCIe core.
add_cells_to_pblock [get_pblocks main_pblock_boot] [get_cells -quiet [<path>]]
IMPORTANT: Do not make any changes to the physical constraints defined in the XDC file because the
constraints are device dependent.
5. Add the Tandem PCIe IP to the Vivado project.
Click Add Sources in the Flow Navigator. In the Add Source wizard, select Add Existing
IP and then browse to the XCI file that was used to create the Tandem PCIe example
design.
6. Copy the appropriate SPI or BPI settings from the example design XDC file and paste
them in your design XDC file.
Update the Vivado settings to run this Tcl file before the bitstream is generated.
7. Implement the design as normal.
Tandem Configuration RTL Design
Tandem Configuration requires slight modifications from the non-tandem PCI Express
product. This section indicates the additional logic integrated within the core and the
additional responsibilities of the user application to implement a Tandem PROM solution.
MUXing Critical Inputs
Certain input ports to the core are multiplexed so that they are disabled during the second
stage configuration process. These MUXes are located in the top-level core file and are
controlled by the user_app_rdy signal.
These inputs are held in a deasserted state while the second stage bitstream is loaded. This
masks off any unwanted glitching due to the absence of second stage drivers and keeps the
PCIe core in a valid state. When user_app_rdy is asserted, the MUXes are switched, and
all interface signals behave as described in this document.
Tandem Completer
In addition to receiving configuration request packets, the PCI Express endpoint might
receive TLP requests that are not processed within the PCI Express hard block. Typical TLP
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requests received are Vendor Defined Messages and Read Requests. To avoid a lockup
scenario within the PCI Express IP, TLP requests must be drained from the core to allow
Configuration requests to be completed successfully.
A completer module is implemented when a Tandem mode is selected to process these
packets. A Tandem Fast PCIe Configuration (FPC) module is implemented to process these
packets. All read requests are expected to be 1DW and a CPLD is returned with a payload of
32’h0. All Vendor Defined Message requests are purged from the cores receive buffer and
no further processing is performed. Each Memory Write request targeting BAR0 is
processed by the FPC and assumed to be second stage bitstream data. The payload is
forwarded to the ICAP. After the second stage bitstream is loaded and user_app_rdy
asserted, the Tandem FPC module becomes inactive.
Tandem Configuration Logic
The core and example design contain ports (signals) specific to Tandem Configuration.
These signals provide handshaking between the first stage (the core) and the second stage
(user logic). Handshaking is necessary for interaction between the core and the user logic.
Table 3-50 defines the handshaking ports on the core.
Table 3-50:
Handshaking Ports
Name
Direction
Polarity
Description
user_app_rdy
Output
Active-High
Identifies when the switch to stage two user logic is complete.
0: Stage two is not yet loaded.
1: Stage two is loaded.
user_reset
Output
Active-High
Can be used to reset PCIe interfacing logic when the PCIe core is
reset. Synchronized with user_clock.
user_clk
Output
N/A
Clock to be used by PCIe interfacing logic.
user_lnk_up
Output
Active-High
Identifies that the PCI Express core is linked up with a host device.
These signals can coordinate events in the user application, such as the release of output
3-state buffers described in Tandem Configuration Details. Here is some additional
information about these signals:
•
user_app_rdy is asserted 2 to 12 clock cycles after stage two is loaded. The delay
ensures that user_app_rdy is not asserted in the middle of a PCIe transaction.
•
user_reset can likewise be used to reset any logic that communicates with the core
when the core itself is reset.
•
user_clk is simply the main internal clock for the PCIe IP core. Use this clock to
synchronize any user logic that communicates directly with the core.
•
user_lnk_up, as the name implies, indicates that the PCIe core is currently running
with an established link.
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In addition to these interface signals, the PCIe IP module interface replicates the ports for
the ICAP (Tandem PCIe only) and STARTUP blocks, as these blocks are instantiated within
the IP core. Look for the icap_* and startup_* ports to connect any user application to
these blocks. The only requirement is that the user application must not access these ports
until user_app_rdy has been asserted, meaning the design is fully operational.
User Application Handshake
An internal completion event must exist within the FPGA for Tandem solutions to perform
the hand-off between core control of the PCI Express Block and the user application.
MUXing Critical Inputs explains why this handoff mechanism is required. The Tandem
solution uses the STARTUP block and the dedicated EOS (End Of Startup) signal to detect
the completion of stage two programming and then switch control of the PCI Express Block
to the user application. When this switch occurs, user_app_rdy is asserted.
If the STARTUP block is required for other functionality within your design, connect to this
primitive through the PCIe IP instantiation. The 13 ports of the STARTUPE2 primitive are
available through the startup_* ports on the IP (Tandem PROM and Tandem PCIe). The
same is true for the five ports of the ICAPE2 primitive, whose ports are named icap_*
(Tandem PCIe only).
Tandem Configuration Details
I/O Behavior
For each I/O that is required for the first stage of a Tandem Configuration design
transceiver, the entire bank in which that I/O resides must be configured in the first stage
bitstream. In addition to this bank, the two configuration banks (14 and 15) are enabled
also, so the following details apply to these three banks (or two, if the reset pin is in a
configuration bank). For PCI Express, the only signal needed in the first stage design is the
sys_rst_n input port. Therefore, any second stage I/O in the same I/O bank as
sys_rst_n port is also configured with the first stage. Any pins in the same I/O bank as
sys_rst_n are unconnected internally, so output pins demonstrate unknown behavior
until their internal connections are completed by second stage configuration. Also,
components requiring initialization for second stage functionality should not be placed in
these I/O banks unless these components are reset by the user_reset signal from PCI
Express.
If output pins must reside in the same bank as the sys_rst_n pin and their value cannot
float prior to stage two completion, the following approach can be taken. Use an OBUFT
that is held in 3-state between stage one completion (when the output becomes active) and
stage two completion (when the driver logic becomes active). The user_app_rdy signal
can be used to control the enable pin, releasing that output when the handshake events
complete.
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TIP: In your top-level design, infer or instantiate an OBUFT. Control the enable (port named T) with
user_app_rdy – watch the polarity!
OBUFT
test_out_obuf (.O(test_out), .I(test_internal), .T(!user_app_rdy));
Using the syntax below as an example, create a Pblock to contain the reset pin location. This
Pblock must have the same BOOT_BLOCK property as the rest of the PCIe IP. In
build_stage1.tcl, these I/O components must be added to Pblocks identified as being
part of the first stage, as they reside in first stage banks. This ensures that the
user_app_rdy connection from the PCIe IP block is active after stage one, actively
holding the enable while stage two loads. It is recommended that they be grouped together
in their own Pblock. The following is an example for an output port named
test_out_obuf.
# Create a new Pblock
create_pblock IO_pblock
# Range the Pblock to just the I/O to be targeted.
# These XY coordinates can be found by calling get_sites on the requested I/O.
resize_pblock -add {IOB_X0Y49:IOB_X0Y49} [get_pblocks IO_pblock]
# Add components and routes to first stage external Pblock
add_cells_to_pblock [get_pblocks IO_pblock] [get_cells test_out_obuf]
# Add this Pblock to the set of Pblocks to be included in the first stage bitstream.
# This ensures the route for user_app_rdy is included in stage one.
set_property BOOT_BLOCK 1 [get_pblocks IO_pblock]
The remaining user I/O in the design are pulled High, by default, during the second stage of
configuration. The use of the PUDC_B pin will, when held High, force all I/O in banks beyond
the three noted above to be tristated. Between stage one and stage two, which for Tandem
PCIe could be a considerable amount of time, these pins are pulled Low by the internal
weak pull-down for each I/O as these pins are unconfigured at that time.
Configuration Pin Behavior
The DONE pin indicates completion of configuration with standard approaches. DONE is
also used for Tandem Configuration, but in a slightly different manner. DONE pulses High at
the end of the first stage, when the start-up sequences are run. It returns Low when stage
two loading begins. For Tandem PROM, this happens immediately because stage two is in
the same bit file. For Tandem PCIe, this happens when the second bitstream is delivered to
the ICAP interface. It pulls High and stays High at the end of the second stage of
configuration.
Configuration Persist (Tandem PROM Only)
Configuration Persist is required in Tandem PROM configuration for 7 series devices. Dual
purpose I/O used for first and second stage configuration cannot be re-purposed as user I/
O after second stage configuration is complete.
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IMPORTANT: Examples for PERSIST settings are shown in the create_bitstreams.tcl script,
generated with the Tandem IP. You must copy the PERSIST, CONFIGRATE and (optionally)
SPI_BUSWIDTH properties to your design XDC file, and modify the values as needed. This action
ensures the PERSIST settings required for the design are not overwritten when the IP core is updated.
If the PERSIST option is set correctly for the needed configuration mode, but necessary
dual-mode I/O pins are still occupied by user I/O, the following error is issued for each
instance during write_bitstream:
ERROR: [Designutils 12-1767] Cannot add persist programming for site IOB_X0Y151.
ERROR: [Designutils 12-1767] Cannot add persist programming for site IOB_X0Y152.
The user I/O occupying these sites must be relocated to use Tandem PROM.
PROM Selection
Configuration PROMs have no specific requirements unique to Tandem Configuration.
However, to meet the 100 ms specification, you must select a PROM that meets the
following three criteria:
1. Supported by Xilinx configuration.
2. Sized appropriately for both first and second stages; that is, the PROM must be able to
contain the entire bitstream.
°
°
For Tandem PROM, both first and second stages are stored here; this bitstream is
slightly larger (4-5%) than a standard bitstream.
For Tandem PCIe, the bitstream size is typically about 1 MB, but this can vary
slightly due to design implementation results, device selection, and effectiveness of
compression.
3. Meets the configuration time requirement for PCI Express based on the f irst-stage
bitstream size and the calculations for the bitstream loading time. See Calculating
Bitstream Load Time for Tandem.
See the 7 Series FPGAs Configuration User Guide (UG470) for a list of supported PROMs and
device bitstream sizes.
Programming the Device
There are no special considerations for programming Tandem bitstreams versus standard
bitstreams into a PROM. You can program a Tandem bitstream using all standard
programming methods, such as JTAG, Slave and Master SelectMAP, SPI, and BPI. Regardless
of the programming method used, the DONE pin is asserted after the f irst stage is loaded
and operation begins.
To prepare for SPI or BPI flash programming, the appropriate settings must be enabled prior
to bitstream generation. This is done by adding the specific flash device settings in the
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design XDC file, as shown here. Examples can be seen in the create_bitstreams.tcl
script. Copy the existing (commented) options to meet your board and flash programming
requirements.
Here are examples for Tandem PROM:
set_property
# This can
set_property
# Set this
BITSTREAM.CONFIG.CONFIGRATE 3 [current_design]
vary up to 66MHz
BITSTREAM.CONFIG.PERSIST BPI16 [current_design]
option to match your flash device requirements
Both internally generated CCLK and externally provided EMCCLK are supported for SPI and
BPI programming. EMCCLK can be used to provide faster conf iguration rates due to tighter
tolerances on the conf iguration clock . See the 7 Series FPGAs Configuration User Guide
(UG470) for details on the use of EMCCLK with the Design Suite.
For more information on configuration in the Vivado Design Suite, see the Vivado Design
Suite User Guide: Programming and Debugging (UG908).
Encrypted Bitstreams
Bitstream encryption is supported for both Tandem PROM and Tandem PCIe for all 7 series
and Zynq devices that support Tandem Configuration.
Increasing the Loading Clock Frequency for Zynq-7000 Devices
Zynq-7000 devices have multiple phases in the boot-up sequence. Two of these phases are
relevant to Tandem Configuration: the loading of the FSBL and the loading of the bitstream.
To ensure that your first-stage Tandem design loads within the boot time requirement,
increase the clock frequencies for loading the bitstream and the FSBL. Verify that your board
layout and PROM selection are appropriate for your desired loading frequencies.
The following sections describe how to increase the loading clock frequencies for the
bitstream and the FSBL.
Note: Although the steps described apply to all Zynq-7000 devices, the Zynq ZC706 development
platform is used for reference where required.
Changing the Bitstream Load Frequency
The default Zynq-7000 device PS configuration uses a QSPI clock frequency of 200 MHz,
which is then divided by eight to generate the bitstream loading clock of 25 MHz. To
increase this loading frequency, decrease the QSPI clock frequency to 166 MHz, and then
divide by two to generate a bitstream loading clock of 83 MHz.
To change the QSPI clock frequency in the Vivado Design Suite:
1. Enable Dual Quad SPI configuration as shown in Figure 3-80.
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a. Select the Peripheral I/O Pins menu.
b. Expand Quad SPI Flash settings.
c. Select Dual Quad SPI (8bit).
X-Ref Target - Figure 3-80
Figure 3-80:
Enable Dual Quad SPI Configuration
2. Modify the Quad SPI clock frequency as shown in Figure 3-81.
a. Select the Clock Configuration menu.
b. Expand IO Peripheral Clocks settings.
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c. Change the QSPI Requested Frequency from 200 MHz to 166 MHz.
X-Ref Target - Figure 3-81
Figure 3-81:
Modify the Quad SPI Clock Frequency
3. After generating the Zynq PS with your required settings, launch the Xilinx Software
Development Kit (SDK).
a. Open the PS block diagram in the Vivado Design Suite.
b. Select File > Export > Export Hardware for SDK.
c. Check the Launch SDK check box and click OK.
4. Generate the Zynq FSBL from the Xilinx SDK.
a. Select File > New > Application Project.
b. In the form, type zynq_fsbl for the project name and click Next.
c. Select Zynq FSBL and click Finish.
5. Modify the QSPI clock frequency to divide by two.
a. Open zynq_fsbl/src/qspi.c in the FSBL source files.
b. Search for XQSPIPS_CLK_PRESCALE_8 and replace it with
XQSPIPS_CLK_PRESCALE_2.
c. Save and compile the file into the FSBL.
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Note: Only divide-by-8 and divide-by-2 should be used in this file.
6. Create the Zynq Boot Image
a. Select Xilinx Tools > Create Zynq Boot Image.
b. Create a new BIF file and select the desired name and location.
c. In the Boot image partitions, select the zynq_fsbl.elf file as the first file.
d. Select the tandem bitstream as the second file.
e. Set the application as the ELF as the third file.
f.
Set the output file name and path as desired.
g. Click Create Image.
7. Load the image to the Quad SPI flash on the ZC706 board.
a. Connect the ZC706 board and ensure that the SW11 DIP switches are at 00000.
b. Select Xilinx Tool > Program Flash.
8. Program the FPGA from the Quad SPI.
a. Turn the ZX706 board power off.
b. Make sure to set SW11 pins to 00010.
c. Turn the board power on.
The Tandem PROM configuration becomes active.
For more information about configuring and using the Zynq PS, see the Zynq-7000 All
Programmable SoC Technical Reference Manual (UG585).
For more information about using the Xilinx SDK for Zynq-7000 devices, see the Zynq-7000
All Programmable SoC Software Developers Guide (UG821).
Tandem PROM/PCIe Resource Restrictions
The PCIe IP must be isolated from the global chip reset (GSR) that occurs right after the
second stage bitstream has completed loading into the FPGA. As a result, first stage and
second stage logic cannot reside within the same configuration frames. Configuration
frames used by the PCIe IP consist of serial transceivers, I/O, FPGA logic, block RAM, or
Clocking, and they (vertically) span a single clock region. The resource restrictions are as
follows:
•
The PCIe IP uses a single MMCM and associated BUFGs to generate the required clocks.
Unused resources within these frames are not available to the user application (second
stage). Additional resources within the clocking frame are the PLL, Phaser, and INOUT
FIFO.
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•
A GT quad contains four serial transceivers. In a X1 or X2 designs, the entire GT quad is
consumed and the unused serial transceivers are not available to the user application.
Current implementations require that two GT quads be consumed regardless of the link
width configuration.
•
DCI Cascading between a first stage I/O bank and a second stage I/O bank is not
supported.
Moving the PCIe Reset Pin
In general, to achieve the best (smallest) first-stage bitstream size, you should consider the
location for any I/Os that are intended to be configured in the first stage. I/Os that are
physically placed a long distance from the core cause extra configuration frames to be
included in the f irst stage. This is due to extra routing resources that are required to include
these I/Os in the f irst stage.
The build_stage1.tcl file automatically traces the reset path to the input pin and adds
the logic appropriately. Ensure that the reset comes from a single pin as show in the
PCI Express example design.
Non-Project Flow
In a non-project environment, the same basic approach as the project environment is used,
but the individual steps for synthesis and implementation are executed directly through Tcl.
First, create the IP using the IP Catalog as shown in the Tandem PCIe KC705 Example Tool
Flow. One of the results of core generation is an .xci file, which is a listing of all the core
details. This file is used to regenerate all the required design sources.
The following is a sample flow in a non-project environment:
1. Read in design sources, either the example design or your design.
read_verilog <verilog_sources>
read_vhdl <vhdl_sources>
read_xdc <xdc_sources>
2. Define the target device.
set_property PART <part> [current_project]
Note: Even though this is a non-project flow, there is an implied project behind the scenes. This
must be done to establish an explicit device before the IP is read in.
3. Read in the PCIe IP.
read_ip pcie_7x_0.xci
4. Synthesize the design. This step generates the IP sources from the .xci input.
synth_design -top <top_level>
Note: The entire IP, including the build_stage1.tcl and create_bitstreams.tcl
sources, will be created each time.
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5. Ensure that any customizations to the design, such as the identification of the
configuration mode to set the persisted pins, are done in the design XDC file.
6. Implement the design. build_stage1.tcl is called automatically prior to opt_design.
opt_design
place_design
route_design
7. Generate the bit files. create_bitstreams.tcl is called automatically. For Tandem
PCIe, the bit file name receives _tandem1 and _tandem2 to differentiate the two
stages. The -bin_file option is only needed for Tandem PCIe.
write_bitstream -bin_file <file>.bit
Simulating the Tandem IP Core
Because the functionality of the Tandem PROM or Tandem PCIe core relies on the STARTUP
module, this must be taken into consideration during simulation.
The PCI Express core relies on the STARTUP block to assert the EOS output status signal in
order to know when the second stage bitstream has been loaded into the device. You must
simulate the STARTUP block behavior to release the PCIe core to work with the second stage
logic. This is done using a hierarchical reference to force the EOS signal on the STARTUP
block. The following pseudo code shows how this could be done.
// Initialize EOS at time 0
force board.EP.pcie_7x_0_support_i.pcie_7x_0_i.inst.inst.pcie_7x_0_fast_cfg_init_cntr_
i.startup_inst.EOS = 1'b1;
<delay until after PCIe reset is released>
// De-assert EOS to simulate the starting of the 2nd stage bitstream loading
force board.EP.pcie_7x_0_support_i.pcie_7x_0_i.inst.inst.pcie_7x_0_fast_cfg_init_cntr_
i.startup_inst.EOS = 1'b0;
<delay a minimum of 4 user_clk cycles>
// Re-assert EOS to simulate that 2nd stage bitstream completed loading
force board.EP.pcie_7x_0_support_i.pcie_7x_0_i.inst.inst.pcie_7x_0_fast_cfg_init_cntr_
i.startup_inst.EOS = 1'b1;
// Simulate as normal from this point on.
The hierarchy to the PCIe core in the line above must be changed to match that of the user
design. This line can also be found in the example simulation provided with the core in the
file named board.v.
Calculating Bitstream Load Time for Tandem
The configuration loading time is a function of the configuration clock frequency and
precision, data width of the configuration interface, and bitstream size. The calculation is
broken down into three steps:
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1. Calculate the minimum clock frequency based on the nominal clock frequency and
subtract any variation from the nominal.
Minimum Clock Frequency = Nominal Clock - Clock Variation
2. Calculate the minimum PROM bandwidth, which is a function of the data bus width,
clock frequency, and PROM type. The PROM bandwidth is the minimum clock frequency
multiplied by the bus width.
PROM Bandwidth = Minimum Clock Frequency * Bus Width
3. Calculate the first-stage bitstream loading time, which is the minimum PROM bandwidth
from step 2, divided by the first-stage bitstream size as reported by
write_bitstream.
First Stage Load Time = (PROM Bandwidth) / (First Stage Bitstream Size)
The first stage bitstream size, reported by write_bitstream, can be read directly
from the terminal or from the log file.
The following is a snippet from the write_bitstream log showing the bitstream size for
the first stage:
Creating bitstream...
Tandem stage1 bitstream contains 13852352 bits.
Tandem stage2 bitstream contains 77690816 bits.
Writing bitstream ./xilinx_pcie_2_1_ep_7x.bit...
These values represent the explicit values of the bitstream stages, whether in one bit file or
two. The effects of bitstream compression are reflected in these values.
Example 1
The configuration for Example 1 is:
•
Quad SPI flash (x4) operating at 66 MHz ± 200 ppm
•
First stage size = 12003648 bits
The steps to calculate the configuration loading time are:
1. Calculate the minimum clock frequency:
66 MHz * (1 - 0.0002) = 65.98 MHz
2. Calculate the minimum PROM bandwidth:
4 bits * 65.98 MHz = 263.92 Mb/s
3. Calculate the first-stage bitstream loading time:
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11.45 Mb / 263.92 Mb/s = ~0.0434 s or 43.4 ms
Example 2
The configuration for Example 2 is:
•
BPI (x16) Synchronous mode, operating at 50 MHz ± 100 ppm
•
First Stage size = 12003648 bits
The steps to calculate the configuration loading time are:
1. Calculate the minimum clock frequency:
50 MHz * (1 - 0.0001) = 49.995 MHz
2. Calculate the minimum PROM bandwidth:
16 bits * 49.995 MHz = 799.92 Mb/s
3. Calculate the first-stage bitstream loading time:
11.45 Mb / 799.92 Mb/s = ~0.0143 s or 14.3 ms
Using Bitstream Compression
Minimizing the first stage bitstream size is the ultimate goal of Tandem Configuration, and
the use of bitstream compression aids in this effort. This option uses a multi-frame write
technique to reduce the size of the bitstream and therefore the configuration time required.
The amount of compression varies from design to design. To enable bitstream compression,
this property is added by default in the create_bitstreams.tcl script:
set_property BITSTREAM.GENERAL.COMPRESS TRUE [current_design]
Other Bitstream Load Time Considerations
Bitstream configuration times can also be affected by:
•
Power supply ramp times, including any delays due to regulators
•
T POR (power on reset)
Power-supply ramp times are design-dependent. Take care to not design in large ramp
times or delays. The FPGA power supplies that must be provided to begin FPGA
configuration are listed in 7 Series FPGAs Configuration User Guide (UG470).
In many cases, the FPGA power supplies can ramp up simultaneously or even slightly before
the system power supply. In these cases, the design gains timing margin because the
100 ms does not start counting until the system supplies are stable. Again, this is
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design-dependent. Systems should be characterized to determine the relationship between
FPGA supplies and system supplies.
T POR is 50 ms for standard power ramp rates, and 35 ms for fast ramp rates for 7 series
devices. See Kintex-7 FPGAs Data Sheet: DC and AC Switching Characteristics (DS182) and
Virtex-7 FPGAs Data Sheet: DC and AC Switching Characteristics (DS183).
Consider two cases for Example 1 (Quad SPI flash [x4] operating at 66 MHz ± 200 ppm) from
Calculating Bitstream Load Time for Tandem:
•
Case 1: Without ATX Supply
•
Case 2: With ATX Supply
Assume that the FPGA power supplies ramp to a stable level (2 ms) after the 3.3V and 12V
system power supplies. This time difference is called TFPGA_PWR. In this case, because the
FPGA supplies ramp after the system supplies, the power supply ramp time takes away from
the 100 ms margin.
The equations to test are:
T POR + Bitstream Load Time + T FPGA_PWR < 100 ms for non-ATX
T POR + Bitstream Load Time + T FPGA_PWR - 100 ms < 100 ms for ATX
Case 1: Without ATX Supply
Because there is no ATX supply, the 100 ms begins counting when the 3.3V and 12 V system
supplies reach within 9% and 8% of their nominal voltages, respectively (see the PCI Express
Card Electromechanical Specification).
50 ms (TPOR) + 43.4 ms (bitstream time) + 2 ms (ramp time) = 96.4 ms
96.4 ms < 100 ms PCIe standard (okay)
In this case, the margin is 3.6 ms.
Case 2: With ATX Supply
ATX supplies provide a PWR_OK signal that indicates when system power supplies are
stable. This signal is asserted at least 100 ms after actual supplies are stable. Thus, this extra
100 ms can be added to the timing margin.
50 ms (TPOR) + 43.4 ms (bitstream time) + 2 ms (ramp time) - 100 ms = -2 ms
3.4 ms < 100 ms PCIe standard (okay)
In this case, the margin is 103.4 ms.
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Sample Bitstream Sizes
The final size of the first stage bitstream varies based on many factors, including:
•
IP: The size and shape of the first-stage Pblocks determine the number of frames
required for stage one.
•
Device: Wider devices require more routing frames to connect the IP to clocking
resources.
•
Design: Location of the reset pin is one of many factors introduced by the addition of
the user application.
•
Variant: Tandem PCIe is a bit larger than Tandem PROM due to the inclusion of the
32-bit connection to the ICAP.
•
Compression: As the device utilization increases, the effectiveness of compression
decreases.
As a baseline, here are some sample bitstream sizes and configuration times for the
example (PIO) design generated along with the PCIe IP.
Table 3-51:
Device
7K160T
7K325T
7VX485T
Example Bitstream Size and Configuration Times(1)
Variant
Full Bitstream
Full: BPI16
at 50 MHz
Tandem Stage Tandem: BPI16
One(2)
at 50 MHz
Tandem PROM
51.1 Mb
63.8 ms
13.1 Mb
16.3 ms
Tandem PCIe
51.1 Mb
63.8 ms
13.6 Mb
17.0 ms
Tandem PROM
87.3 Mb
109.1 ms
16.6 Mb
20.7 ms
Tandem PCIe
87.3 Mb
109.1 ms
20.9 Mb
26.2 ms
Tandem PROM
154.7 Mb
193.3 ms
23.6 Mb
29.5 ms
Tandem PCIe
154.7 Mb
193.3 ms
27.8 Mb
34.7 ms
Notes:
1. The configuration times shown here do not include T POR .
2. Because the PIO design is very small, compression is very effective in reducing the bitstream size. These numbers
were obtained without compression to give a more accurate estimate for what a full design might show. These
numbers were generated using a PCIe Gen2x8 configuration in Vivado Design Suite 2015.1.
The amount of time it takes to load the second-stage bitstream using the Tandem PCIe
methodology depends on three additional factors:
•
The width and speed of PCI Express link.
•
The frequency of the clock used to program the ICAP.
•
The efficiency at which the Root Port host can deliver the bitstream to the endpoint
FPGA design. For most designs this will be the limiting factor.
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The lower bandwidth of these three factors determines how fast the second-stage bitstream
is loaded.
Clocking
Figure 3-82 shows the clocking diagram for this core.
X-Ref Target - Figure 3-82
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*HQ[
3FLHB[
,%8)'6
6<6B&/.
V\VBFON
3LSHBFORFN
SLSHBGFONBLQ
&/.B'&/.
&/.B3&/.
&/.B22%&/.
&/.B5;865&/.
SLSHBSFONBLQ
SLSHBRREFONBLQ
SLSHBU[XVUFONBLQ
&/.B86(5&/.
&/.B86(5&/.
SLSHBXVHUFONBLQ
SLSHBXVHUFONBLQ
XVHUBFONBRXW
&/.B7;287&/.
&/.B3&/.B6(/
SLSHBPPFPBORFNBLQ
&/.B00&0B/2&.
SLSHBW[RXWFONBRXW
SLSHBSFONBVHOBRXW
;
Figure 3-82:
Clocking Diagram
The integrated block input system clock signal is called sys_clk. The core requires a
100 MHz, 125 MHz, or 250 MHz clock input. The clock frequency used must match the clock
frequency selection in the Vivado IDE.
In a typical PCI Express solution, the PCI Express reference clock is a Spread Spectrum Clock
(SSC), provided at 100 MHz. In most commercial PCI Express systems, SSC cannot be
disabled. For more information regarding SSC and PCI Express, see section 4.3.1.1.1 of the
PCI Express Base Specification [Ref 2].
Synchronous and Non-Synchronous Clocking
There are two ways to clock the PCI Express system:
•
Using synchronous clocking, where a shared clock source is used for all devices.
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•
Using non-synchronous clocking, where each device has its own clock source. ASPM
must not be used in systems with non-synchronous clocking. When this mode is used,
set the PCIE_ASYNC_EN to TRUE. For more details, AR 52400.
RECOMMENDED: Use synchronous clocking when using the core. All add-in card designs must use
synchronous clocking due to the characteristics of the provided reference clock. For devices using the
Slot clock, the Slot Clock Conf iguration setting in the Link Status Register must be enabled in the
Vivado IDE. See the 7 Series FPGAs GTX Transceivers User Guide (UG476) and device data sheet for
additional information regarding reference clock requirements.
For synchronous clocked systems, each link partner device shares the same clock source.
Figure 3-83 and Figure 3-85 show a system using a 100 MHz reference clock. When
using the 125 MHz or the 250 MHz reference clock option, an external PLL must be used
to do a multiply of 5/4 and 5/2 to convert the 100 MHz clock to 125 MHz and 250 MHz,
respectively, as illustrated in Figure 3-84 and Figure 3-86.
Further, even if the device is part of an embedded system, if the system uses commercial
PCI Express root complexes or switches along with typical motherboard clocking
schemes, synchronous clocking should still be used as shown in Figure 3-83 and
Figure 3-84.
Figure 3-83 through Figure 3-86 illustrate high-level representations of the board
layouts. You must ensure that proper coupling, and termination are used when laying
out the board.
X-Ref Target - Figure 3-83
Embedded System Board
PCI Express
Switch or Root
Complex
Device
PCIe Link
PCIe Link
G
T
X
7 Series FPGA
Endpoint
100 MHz
PCI Express
Clock Oscillator
100 MHz
UG477_c5_67_092110
Figure 3-83:
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X-Ref Target - Figure 3-84
Embedded System Board
PCI Express
Switch or Root
Complex
Device
PCIe Link
G
T
X
PCIe Link
7 Series FPGA
Endpoint
100 MHz
125/250 MHz
100 MHz
PCI Express
Clock Oscillator
External PLL
UG477_c5_68_092110
Figure 3-84:
Embedded System Using 125/250 MHz Reference Clock
X-Ref Target - Figure 3-85
PCI Express Add-In Card
7 Series FPGA
Endpoint
100 MHz with SSC
PCI Express Clock
PCIe Link
PCIe Link
GTX
Transceivers
PCI Express Connector
PCIe Link
_
PCIe Link
+
UG477_c5_69_092110
Figure 3-85:
Open System Add-In Card Using 100 MHz Reference Clock
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X-Ref Target - Figure 3-86
PCI Express Add-In Card
+
External PLL
125/250 MHz
7 Series FPGA
Endpoint
GTX
Transceivers
-
PCIe Link
100 MHz with SSC
PCI Express Clock
PCIe Link
+
PCIe Link
PCIe Link
PCI Express Connector
UG477_c5_70_092110
Figure 3-86:
Open System Add-In Card Using 125/250 MHz Reference Clock
Resets
The 7 Series FPGAs Integrated Block for PCI Express core uses sys_rst_n to reset the
system, an asynchronous, active-Low reset signal asserted during the PCI Express
Fundamental Reset. Asserting this signal causes a hard reset of the entire core, including
the GTX transceivers. After the reset is released, the core attempts to link train and resume
normal operation. In a typical Endpoint application, for example, an add-in card, a sideband
reset signal is normally present and should be connected to sys_rst_n. For Endpoint
applications that do not have a sideband system reset signal, the initial hardware reset
should be generated locally. Three reset events can occur in PCI Express:
•
Cold Reset. A Fundamental Reset that occurs at the application of power. The signal
sys_rst_n is asserted to cause the cold reset of the core.
•
Warm Reset. A Fundamental Reset triggered by hardware without the removal and
re-application of power. The sys_rst_n signal is asserted to cause the warm reset to
the core.
•
Hot Reset: In-band propagation of a reset across the PCI Express Link through the
protocol. In this case, sys_rst_n is not used. In the case of Hot Reset, the
received_hot_reset signal is asserted to indicate the source of the reset.
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The user application interface of the core has an output signal called
user_reset_out. This signal is deasserted synchronously with respect to
user_clk_out. Signal user_reset_out is asserted as a result of any of these
conditions:
•
Fundamental Reset: Occurs (cold or warm) due to assertion of sys_rst_n.
•
PLL within the Core Wrapper: Loses lock, indicating an issue with the stability of the
clock input.
•
Loss of Transceiver PLL Lock: Any transceiver loses lock, indicating an issue with the
PCI Express Link.
The user_reset_out signal deasserts synchronously with user_clk_out after all of the
above conditions are resolved, allowing the core to attempt to train and resume normal
operation.
IMPORTANT: Systems designed to the PCI Express electro-mechanical specification provide a sideband
reset signal, which uses 3.3V signaling levels—see the FPGA device data sheet to understand the
requirements for interfacing to such signals.
Protocol Layers
The functions of the protocol layers, as defined by the PCI Express Base Specification [Ref 2],
include generation and processing of transaction layer packets (TLPs), flow control
management, initialization, power management, data protection, error checking and retry,
physical link interface initialization, maintenance and status tracking, serialization,
deserialization, and other circuitry for interface operation. Each layer is defined in the next
subsections.
Transaction Layer
The Transaction Layer is the upper layer of the PCI Express architecture, and its primary
function is to accept, buffer, and disseminate Transaction Layer packets or TLPs. TLPs
communicate information through the use of memory, I/O, configuration, and message
transactions. To maximize the efficiency of communication between devices, the
Transaction Layer enforces PCI compliant Transaction ordering rules and manages TLP
buffer space through credit-based flow control.
Data Link Layer
The Data Link Layer acts as an intermediate stage between the Transaction Layer and the
Physical Layer. Its primary responsibility is to provide a reliable mechanism for the exchange
of TLPs between two components on a link.
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Services provided by the Data Link Layer include data exchange (TLPs), error detection and
recovery, initialization services and the generation and consumption of Data Link Layer
Packets (DLLPs). DLLPs are used to transfer information between Data Link Layers of two
directly connected components on the link. DLLPs convey information such as Power
Management, Flow Control, and TLP acknowledgments.
Physical Layer
The Physical Layer interfaces the Data Link Layer with signaling technology for link data
interchange, and is subdivided into the Logical sub-block and the Electrical sub-block.
•
The Logical sub-block frames and deframes TLPs and DLLPs. It also implements the Link
Training and Status State machine (LTSSM), which handles link initialization, training,
and maintenance. Scrambling, descrambling, and 8B/10B encoding and decoding of
data is also performed in this sub-block.
•
The Electrical sub-block defines the input and output buffer characteristics that
interfaces the device to the PCIe® link.
The Physical Layer also supports Lane Reversal (for multi-lane designs) and Lane Polarity
Inversion, as indicated in the PCI Express Base Specification, rev. 2.1 [Ref 2] requirement.
Configuration Management
The Configuration Management layer maintains the PCI™ Type 0 Endpoint configuration
space and supports these features:
•
Implements the PCI Configuration Space
•
Supports Configuration Space accesses
•
Power Management functions
•
Implements error reporting and status functionality
•
Implements packet processing functions
°
Receive
-
°
•
Configuration Reads and Writes
Transmit
-
Completions with or without data
-
Transaction Layer Module (TLM) Error Messaging
-
User Error Messaging
-
Power Management Messaging/Handshake
Implements MSI and INTx interrupt emulation
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•
Optionally implements MSIx Capability Structure in the PCI Configuration Space
•
Optionally implements the Device Serial Number Capability in the PCI Express Extended
Capability Space
•
Optionally implements Virtual Channel Capability (support only for VC0) in the
PCI Express Extended Capability Space
•
Optionally implements Xilinx defined Vendor Specific Capability Structure in the
PCI Express Extended Capability space to provide Loopback Control and Status
•
Optionally implements Advanced Error Reporting (AER) Capability Structure in the PCI
Express Extended Configuration Space
•
Optionally implements Resizable BAR (RBAR) Capability Structure in the PCI Express
Extended Configuration Space
Shared Logic
This new feature allows you to share common logic across multiple instances of PCIe Blocks
or with other cores with certain limitations. The Shared Logic feature minimizes the HDL
modifications needed by bringing the logic to be shared to the top module of the design;
it also enables additional ports on the top module to enable sharing. This feature is
applicable for both Endpoint mode and Root Port mode.
In the Vivado Design Suite, the shared logic options are available in the Shared Logic page
when customizing the core.
There are four types of logic sharing:
•
Shared Clocking
•
Shared GT_COMMON
•
Shared GT_COMMON and Clocking
•
Internal Shared GT_COMMON and Clocking
IMPORTANT: For Shared Clocking option Include Shared Logic (Clocking) in example design (default
mode), Shared GT_COMMON option Include Shared Logic (Transceiver GT_COMMON) in example
design, and Shared GT_COMMON and Clocking, to generate the corresponding modules in the support
directory, you must run the Open IP Example Design command after the output products are generated.
For the option Include Shared Logic in Core, these modules are generated in the source directory.
Shared Clocking
To use the share clocking feature, select Include Shared Logic (Clocking) in example
design option in the in the Shared Logic tab (Figure 3-87).
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When this feature is selected, the mixed-mode clock manager (MMCM) instance is removed
from the pipe wrappers and is moved into the support wrapper of the example design. It
also brings out additional ports to the top level to enable sharing of the clocks.
You also have the option to modify and use the unused outputs of the MMCM.
X-Ref Target - Figure 3-87
Figure 3-87:
Shared Clocking
The MMCM generates the following clocks for PCIe solution wrapper:
•
clk_125mhz - 125 MHz clock.
•
clk_250mhz - 250 MHz clock.
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•
userclk - 62.5 MHz / 125 MHz / 250 MHz clock, depending on selected PCIe core lane
width, link speed, and AXI interface width.
•
userclk2 – 250 MHz / 500 MHz clock, depending on selected PCIe core link speed.
•
oobclk
The other cores/logic present in the user design can use any of the MMCM outputs listed
above.
The MMCM instantiated in the PCIe example design has two unconnected outputs:
CLKOUT5, and CLKOUT6. These outputs can be used to generate other desired clock
frequencies by selecting the appropriate CLKOUT5_DIVIDE and CLKOUT6_DIVIDE
parameters for MMCM.
TIP: Sharing the MMCM between PCIe and other cores in your design saves FPGA resources and eases
output clock path routing.
Limitations
•
Reference clock input to MMCM is restricted to 100 MHz in most use cases.
°
There is an option for selecting a reference clock of 125MHz or 250MHz, which is
not a common use case.
•
The MMCM reset is tied to a static value in the top module. The MMCM can be reset as
required by the system design. The MMCM reset can be asserted only after reference
clock is recovered and is stable. Also, MMCM reset is indirectly tied to the PCIe core
reset and asserting MMCM reset resets the PCIe core.
•
Userclk1 and Userclk2 outputs are selected based on the PCIe Lane Width, Link
Speed, and AXI width selections (for details, see Chapter 4, Customizing and
Generating the Core). Sharing cores must comply with these requirements.
Shared GT_COMMON
A quad phase-locked loop (QPLL) in GT_COMMON can serve a quad of GT_CHANNEL
instances. If the PCIe core is configured as X1 or X2 and is using a QPLL, the remaining
GT_CHANNEL instances can be used by other cores by sharing the same QPLL and
GT_COMMON.
To use the shared GT_COMMON instances, select the Include Shared Logic (Transceiver
GT_COMMON) in example design option in the Shared Logic tab (Figure 3-88).
When this feature is selected, the GT_COMMON instance is removed from the pipe
wrappers and is moved into the support wrapper of the example design. It also brings out
additional ports to the top level to enable sharing of the GT_COMMON.
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Shared logic feature for GT_COMMON helps save FPGA resources and also eases dedicated
clock routing within the single GT quad.
Shared GT_COMMON Use Cases with GTX and GTP
Table 3-52:
Shared GT_COMMON Use Cases
GT – PCIe max Link
Speed
Device – PCIe Max Link Speed
Shared GT_COMMON
GTX
Kintex-7, Virtex-7 (485T) – PCIe
Gen2
PCIe design instantiates and uses the
GT_COMMON instance. Shared IP can use
the GT_COMMON as long as it can use the
same QPLL clock frequencies.
GTP
Artix-7 – PCIe Gen2
GTP_COMMON has 2 QPLLs. PCIe design
only uses one QPLL. The remaining one can
be used by shared IP core.
Limitations
•
The reset logic in the pipe wrapper resets the QPLL when the PCIe Block performs a
rate change. When sharing is enabled, the core/logic which is sharing the QPLL must be
able to handle and recover from this reset.
•
The settings of the GT_COMMON should not be changed as they are optimized for the
PCIe core.
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X-Ref Target - Figure 3-88
Figure 3-88:
Shared GT_COMMON
Shared GT_COMMON and Clocking
Both the GT_COMMON and Clocks can be shared when you select Include Shared Logic
(Clocking) in example design and Include Shared Logic (Transceiver GT_COMMON) in
example design in the Shared Logic tab (see Figure 3-89).
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X-Ref Target - Figure 3-89
Figure 3-89:
Shared GT_COMMON and Clocking
Internal Shared GT_COMMON and Clocking
This feature allows sharing of GT_COMMON and Clocks while these modules are still
internal to the core (not brought up to the support wrapper). It can be enabled when you
select Include Shared Logic in Core in the Shared Logic tab (see Figure 3-90).
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X-Ref Target - Figure 3-90
Figure 3-90:
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Clocking Interface
Table 3-53 defines the clocking interface signals.
Table 3-53:
Clocking Interface Signals
Name
Direction
Description
pipe_pclk_in
Input
Parallel clock used to synchronize data transfers across the parallel
interface of the GTX transceiver.
pipe_rxusrclk_in
Input
Provides a clock for the internal RX PCS datapath.
pipe_rxoutclk_in
Input
Recommended clock output to the FPGA logic.
pipe_dclk_in
Input
Dynamic reconfiguration clock.
pipe_userclk1_in
Input
Optional user clock.
pipe_userclk2_in
Input
Optional user clock.
pipe_mmcm_lock_in
Input
Indicates if the MMCM is locked onto the source CLK.
pipe_txoutclk_out
Output
Recommended clock output to the FPGA logic.
pipe_rxoutclk_out
Output
Recommended clock output to the FPGA logic.
pipe_pclk_sel_out
Output
Parallel clock select.
pipe_gen3_out
Output
Indicates the PCI Express operating speed.
pipe_mmcm_rst_n
MMCM reset port. This port could be used by the upper layer to
reset MMCM if error recovery is required. If the system detects the
deassertion of MMCM lock, Xilinx recommends that you reset the
MMCM. The recommended approach is to reset the MMCM after
the MMCM input clock recovers (if MMCM reset occurs before the
input reference clock recovers, the MMCM might never relock).
After MMCM is reset, wait for MMCM to lock and then reset the
PIPE Wrapper as normally done. Currently this port is tied High.
The Clocking architecture is described in detail in the Use Model chapter of the 7 Series
FPGAs GTX/GTH Transceivers User Guide (UG476) [Ref 12].
FPGA Configuration
This section discusses how to configure the 7 series FPGA so that the device can link up and
be recognized by the system. This information is provided for you to choose the correct
FPGA configuration method for the system and verify that it works as expected.
This section discusses how specific requirements of the PCI Express Base Specification and
PCI Express Card Electromechanical Specification [Ref 2] apply to FPGA configuration.
RECOMMENDED: Where appropriate, Xilinx recommends that you read the actual specifications for
detailed information.
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See Tandem PROM, page 156 for more information on meeting configuration requirements
after reading this section.
This section contains these subsections:
•
Configuration Terminology. Defines terms used in this section.
•
Configuration Access Time. Several specification items govern when an Endpoint
device needs to be ready to receive configuration accesses from the host (Root
Complex).
•
Board Power in Real-World Systems. Understanding real-world system constraints
related to board power and how they affect the specification requirements.
•
Recommendations. Describes methods for FPGA configuration and includes sample
issue analysis for FPGA configuration timing issues.
Configuration Terminology
In this section, these terms are used to differentiate between FPGA configuration and
configuration of the PCI Express® device:
•
Configuration of the FPGA. FPGA configuration is used.
•
Configuration of the PCI Express device. After the link is active, configuration is used.
Configuration Access Time
In standard systems for PCI Express, when the system is powered up, configuration software
running on the processor starts scanning the PCI Express bus to discover the machine
topology.
The process of scanning the PCI Express hierarchy to determine its topology is referred to as
the enumeration process. The root complex accomplishes this by initiating configuration
transactions to devices as it traverses and determines the topology.
All PCI Express devices are expected to have established the link with their link partner and
be ready to accept configuration requests during the enumeration process. As a result,
there are requirements as to when a device needs to be ready to accept configuration
requests after powerup; if the requirements are not met, this occurs:
•
If a device is not ready and does not respond to configuration requests, the root
complex does not discover it and treats it as non-existent.
•
The operating system does not report the existence of the device, and the user
application is not able to communicate with the device.
Choosing the appropriate FPGA configuration method is key to ensuring the device is able
to communicate with the system in time to achieve link up and respond to the
configuration accesses.
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Configuration Access Specification Requirements
Two PCI Express specification items are relevant to configuration access:
1. Section 6.6 of PCI Express Base Specification, rev 1.1 states “A system must guarantee
that all components intended to be software visible at boot time are ready to receive
Configuration Requests within 100 ms of the end of Fundamental Reset at the Root
Complex.” For detailed information about how this is accomplished, see the
specification [Ref 2].
Xilinx compliance to this specification is validated by the PCI Express-CV tests. The PCI
Special Interest Group (PCI-SIG) provides the PCI Express Configuration Test Software to
verify the device meets the requirement of being able to receive configuration accesses
within 100 ms of the end of the fundamental reset. The software, available to any
member of the PCI-SIG, generates several resets using the in-band reset mechanism and
PERST# toggling to validate robustness and compliance to the specification.
2. Section 6.6 of PCI Express Base Specification v1.1 [Ref 2] defines three parameters
necessary “where power and PERST# are supplied.” The parameter TPVPERL applies to
FPGA configuration timing and is defined as:
T PVPERL - PERST# must remain active at least this long after power becomes valid.
The PCI Express Base Specification does not give a specific value for TPVPERL – only its
meaning is defined. The most common form factor used with the core is an ATX-based
form factor. The PCI Express Card Electromechanical Specification [Ref 2] focuses on
requirements for ATX-based form factors. This applies to most designs targeted to
standard desktop or server type motherboards. Figure 3-91 shows the relationship
between Power Stable and PERST#.
X-Ref Target - Figure 3-91
Power Stable
3.3 VAUX
3.3V/12V
PERST#
PCI Express Link
Inactive
Active
100 ms
T
PVPERL
Figure 3-91:
Power Up
Section 2.6.2 of the PCI Express Card Electromechanical Specification, v1.1 [Ref 2] defines
T PVPREL as a minimum of 100 ms, indicating that from the time power is stable the system
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reset is asserted for at least 100 ms (as shown in Table 3-54).
Table 3-54:
TPVPERL Specification
Symbol
Parameter
T PVPERL
Min
Power stable to PERST#
inactive
100
Max
Units
ms
From Figure 3-91 and Table 3-54, it is possible to obtain a simple equation to define the
FPGA configuration time as follows:
FPGA Configuration Time ≤ T PWRVLD + T PVPERL
Equation 3-1
Given that TPVPERL is defined as 100 ms minimum, this becomes:
FPGA Configuration Time ≤ T PWRVLD + 100 ms
Equation 3-2
Note: Although TPWRVLD is included in Equation 3-2, it has yet to be defined in this discussion
because it depends on the type of system in use. The Board Power in Real-World Systems section
defines T PWRVLD for both ATX-based and non ATX-based systems.
FPGA configuration time is only relevant at cold boot; subsequent warm or hot resets do
not cause reconfiguration of the FPGA. If the design appears to be having issues due to
FPGA configuration, you should issue a warm reset as a simple test, which resets the system,
including the PCI Express link, but keeps the board powered. If the issue does not appear,
the issue could be FPGA configuration time related.
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Board Power in Real-World Systems
Several boards are used in PCI Express systems. The ATX Power Supply Design specification,
endorsed by Intel, is used as a guideline and for this reason followed in the majority of
mother boards and 100% of the time if it is an Intel-based motherboard. The relationship
between power rails and power valid signaling is described in the ATX 12V Power Supply
Design Guide [Ref 22]. Figure 3-92, redrawn here and simplified to show the information
relevant to FPGA configuration, is based on the information and diagram found in section
3.3 of the ATX 12V Power Supply Design Guide. For the entire diagram and definition of all
parameters, see the ATX 12V Power Supply Design Guide.
Figure 3-92 shows that power stable indication from Figure 3-91 for the PCI Express system
is indicated by the assertion of PWR_OK. PWR_OK is asserted High after some delay when
the power supply has reached 95% of nominal.
X-Ref Target - Figure 3-92
T1
VAC
PS_ON#
+12 VDC
+5 VDC
+3.3 VDC
95%
O/Ps
10%
T2
T3
PWR_OK
T4
T1 = Power On Time (T1 < 500 ms)
T2 = Rise Time (0.1 ms <= T2 <= 20 ms)
T3 = PWR_OK Delay (100 ms < T3 < 500 ms)
T4 = PWR_OK Rise Time (T4 <= 10 ms)
Figure 3-92:
ATX Power Supply
Figure 3-92 shows that power is valid before PWR_OK is asserted High. This is represented
by T3 and is the PWR_OK delay. The ATX 12V Power Supply Design Guide defines PWR_OK
as 100 ms < T3 < 500 ms, indicating that from the point at which the power level reaches
95% of nominal, there is a minimum of at least 100 ms but no more than 500 ms of delay
before PWR_OK is asserted. Remember, according to the PCI Express Card Electromechanical
Specification [Ref 2], the PERST# is guaranteed to be asserted a minimum of 100 ms from
when power is stable indicated in an ATX system by the assertion of PWR_OK.
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Again, the FPGA configuration time equation is:
FPGA Configuration Time ≤ T PWRVLD + 100 ms
Equation 3-3
T PWRVLD is defined as PWR_OK delay period; that is, TPWRVLD represents the amount of time
that power is valid in the system before PWR_OK is asserted. This time can be added to the
amount of time the FPGA has to configure. The minimum values of T2 and T4 are negligible
and considered zero for purposes of these calculations. For ATX-based motherboards,
which represent the majority of real-world motherboards in use, T PWRVLD can be defined as:
100 ms ≤ T PWRVLD ≤ 500 ms
Equation 3-4
This provides these requirements for FPGA configuration time in both ATX and
non-ATX-based motherboards:
•
FPGA Configuration Time ≤ 200 ms (for ATX based motherboard)
•
FPGA Configuration Time ≤ 100 ms (for non-ATX based motherboard)
The second equation for the non-ATX based motherboards assumes a TPWRVLD value of
0 ms because it is not defined in this context. Designers with non-ATX based motherboards
should evaluate their own power supply design to obtain a value for TPWRVLD.
This section assumes that the FPGA power (VCCINT) is stable before or at the same time that
PWR_OK is asserted. If this is not the case, then additional time must be subtracted from the
available time for FPGA configuration.
IMPORTANT: Avoid designing add-in cards with staggered voltage regulators with long delays.
Hot Plug Systems
Hot Plug systems generally employ the use of a Hot-Plug Power Controller located on the
system motherboard. Many discrete Hot-Plug Power Controllers extend TPVPERL beyond the
minimum 100 ms. Add-in card designers should consult the Hot-Plug Power Controller data
sheet to determine the value of TPVPERL. If the Hot-Plug Power Controller is unknown, then
a TPVPERL value of 100 ms should be assumed.
Recommendations
RECOMMENDED: For minimum FPGA configuration time, Xilinx recommends the BPI configuration
mode with a parallel NOR flash, which supports high-speed synchronous read operation.
In addition, an external clock source can be supplied to the external master configuration
clock (EMCCLK) pin to ensure a consistent configuration clock frequency for all conditions.
See 7 Series FPGAs Configuration User Guide (UG470) [Ref 7] for descriptions of the BPI
configuration mode and EMCCLK pin. This section discusses these recommendations and
includes sample analysis of potential issues that might arise during FPGA configuration.
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FPGA Configuration Times for 7 Series Devices
During powerup, the FPGA configuration sequence is performed in four steps:
1. Wait for power on reset (POR) for all voltages (VCCINT, VCCAUX , and VCCO_0) in the FPGA
to trip, referred to as POR Trip Time.
2. Wait for completion (deassertion) of INIT_B to allow the FPGA to initialize before
accepting a bitstream transfer.
Note: As a general rule, steps 1 and 2 require ≤ 50 ms
3. Wait for assertion of DONE, the actual time required for a bitstream to transfer depends
on:
°
Bitstream size
°
Clock (CCLK) frequency
°
Transfer mode (and data bus width) from the flash device
-
SPI = Serial Peripheral Interface (x1, x2, or x4)
-
BPI = Byte Peripheral Interface (x8 or x16)
Bitstream transfer time can be estimated using this equation.
Bitstream transfer time = (bitstream size in bits)/(CCLK frequency)/ (data bus width in bits)
Equation 3-5
For detailed information about the configuration process, see the 7 Series FPGAs
Configuration User Guide (UG470) [Ref 7].
Sample Issue Analysis
This section presents data from an ASUS PL5 system to demonstrate the relationships
between Power Valid, FPGA Configuration, and PERST#. Figure 3-93 shows a case where the
Endpoint failed to be recognized due to a FPGA configuration time issue. Figure 3-94 shows
a successful FPGA configuration with the Endpoint being recognized by the system.
Failed FPGA Recognition
Figure 3-93 illustrates an example of a cold boot where the host failed to recognize the
Xilinx FPGA. Although a second PERST# pulse assists in allowing more time for the FPGA to
configure, the slowness of the FPGA configuration clock (2 MHz) causes configuration to
complete well after this second deassertion. During this time, the system enumerated the
bus and did not recognize the FPGA.
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X-Ref Target - Figure 3-93
Figure 3-93:
Host Fails to Recognize FPGA Due to Slow Configuration Time
Successful FPGA Recognition
Figure 3-94 illustrates a successful cold boot test on the same system. In this test, the CCLK
was running at 50 MHz, allowing the FPGA to configure in time to be enumerated and
recognized. The figure shows that the FPGA began initialization approximately 250 ms
before PWR_OK. DONE going High shows that the FPGA was configured even before
PWR_OK was asserted.
X-Ref Target - Figure 3-94
Figure 3-94:
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Workarounds for Closed Systems
For failing FPGA configuration combinations, designers might be able to work around the
issue in closed systems or systems where they can guarantee behavior. These options are
not recommended for products where the targeted end system is unknown.
1. Check if the motherboard and BIOS generate multiple PERST# pulses at start-up. This
can be determined by capturing the signal on the board using an oscilloscope. This is
similar to what is shown in Figure 3-93. If multiple PERST# pulses are generated, this
typically adds extra time for FPGA configuration.
Define TPERSTPERIOD as the total sum of the pulse width of PERST# and deassertion
period before the next PERST# pulse arrives. Because the FPGA is not power cycled or
reconfigured with additional PERST# assertions, the TPERSTPERIOD number can be added
to the FPGA configuration equation.
FPGA Configuration Time ≤ T PWRVLD + T PERSTPERIOD + 100 ms
Equation 3-6
2. In closed systems, it might be possible to create scripts to force the system to perform
a warm reset after the FPGA is configured, after the initial powerup sequence. This
resets the system along with the PCI Express subsystem allowing the device to be
recognized by the system.
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Chapter 4
Design Flow Steps
This chapter describes customizing and generating the core, constraining the core, and the
simulation, synthesis and implementation steps that are specific to this IP core. More
detailed information about the standard Vivado® design flows and the Vivado IP integrator
can be found in the following Vivado Design Suite user guides:
•
Vivado Design Suite User Guide: Designing IP Subsystems using IP Integrator (UG994)
[Ref 19]
•
Vivado Design Suite User Guide: Designing with IP (UG896) [Ref 15]
•
Vivado Design Suite User Guide: Getting Started (UG910) [Ref 14]
•
Vivado Design Suite User Guide: Logic Simulation (UG900) [Ref 16]
Customizing and Generating the Core
This section includes information on using the Vivado Design Suite to customize and
generate the core.
Note: If you are customizing and generating the core in the IP integrator, see the Vivado Design
Suite User Guide: Designing IP Subsystems using IP Integrator (UG994) [Ref 19] for detailed
information. IP integrator might auto-compute certain configuration values when validating or
generating the design. To check whether the values do change, see the description of the parameter
in this section. To view the parameter value you can run the validate_bd_design command in the
Tcl Console.
The 7 Series FPGAs Integrated Block for PCI Express® core is a fully configurable and highly
customizable solution. In the Vivado Integrated Design Environment (IDE), you can
customize the IP for use in your design by specifying values for the various parameters
associated with the IP core using the following steps:
1. Select the IP from the IP catalog.
2. Double-click the selected IP, or select the Customize IP command from the toolbar or
right-click menu.
The Customize IP dialog box for the 7 Series FPGAs Integrated Block for PCI Express consists
of two modes: Base Mode and Advanced Mode. To select a mode, use the Mode drop-down
list on the first page of the Customize IP dialog box.
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For details, see the Vivado Design Suite User Guide: Designing with IP (UG896) [Ref 15], and
the Vivado Design Suite User Guide: Getting Started (UG910) [Ref 14].
Note: Figures in this chapter are illustrations of the Vivado IDE. This layout might vary from the
current version.
Base Mode
The Base mode parameters are explained in this section.
Basic
The initial customization page shown in Figure 4-1 is used to define the basic parameters
for the core, including the component name, lane width, and link speed.
X-Ref Target - Figure 4-1
Figure 4-1:
Basic Parameters
Component Name
Base name of the output files generated for the core. The name must begin with a letter and
can be composed of these characters: a to z, 0 to 9, and “_.”
Mode
Allows to select the Basic or Advanced mode of the configuration of the core.
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Device / Port Type
Indicates the PCI Express logical device type.
PCIe Block Location
Selects from the Integrated Blocks available to enable generation of location specific
constraint files and pinouts.
This option is not available if a Xilinx Development Board is selected.
Xilinx Development Board
Selects the Xilinx Development Board to enable the generation of Xilinx Development
Board specific constraints files.
Silicon Revision
Selects the Silicon Revision. The possible options are Initial_ES or GES_and_Production.
Number of Lanes
The 7 Series FPGAs Integrated Block for PCI Express requires the selection of the initial lane
width. Table 4-1 defines the available widths and associated generated core. Wider lane
width cores are capable of training down to smaller lane widths if attached to a smaller
lane-width device. See Link Training: 2-Lane, 4-Lane, and 8-Lane Components, page 141 for
more information.
Table 4-1:
Lane Width and Product Generated
Lane Width
Product Generated
x1
1-Lane 7 Series FPGAs Integrated Block for PCI Express
x2
2-Lane 7 Series FPGAs Integrated Block for PCI Express
x4
4-Lane 7 Series FPGAs Integrated Block for PCI Express
x8
8-Lane 7 Series FPGAs Integrated Block for PCI Express
Maximum Link Speed
The 7 Series FPGAs Integrated Block for PCI Express allows the selection of maximum link
speed supported by the device. Table 4-2 defines the lane widths and link speeds
supported by the device. Higher link speed cores are capable of training to a lower link
speed if connected to a lower link speed capable device.
Table 4-2:
Lane Width and Link Speed
Lane Width
Link Speed
x1
2.5 Gb/s, 5 Gb/s
x2
2.5 Gb/s, 5 Gb/s
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Table 4-2:
Lane Width and Link Speed
Lane Width
Link Speed
x4
2.5 Gb/s, 5 Gb/s
x8
2.5 Gb/s, 5 Gb/s
AXI Interface Frequency
It is possible to select the clock frequency of the core user interface. Each lane width
provides multiple frequency choices: a default frequency, and alternative frequencies, as
defined in Table 4-3.
RECOMMENDED: Where possible, use the default frequency.
Selecting the alternate frequencies does not result in a difference in throughput in the core,
but does allow the user application to run at an alternate speed.
Table 4-3:
Recommended and Optional Transaction Clock (user_clk_out) Frequencies
Product
Link Speed
(Gb/s)
Interface Width(1)
(Bits)
1-lane
2.5
64
62.5
125, 250
1-lane
5
64
62.5
125, 250
2-lane
2.5
64
62.5
125, 250
2-lane
5
64
125
250
4-lane
2.5
64
125
250
4-lane
5
64
250
-
4-lane
5
128
125
-
8-lane
2.5
64
250
-
8-lane
2.5
128
125
-
8-lane
5
128
250
-
Recommended Optional Frequency
Frequency (MHz)
(MHz)(2)
Notes:
1. Interface width is a static selection and does not change with dynamic link speed changes.
2. For all Artix-7 devices when speed grade -1, -1i, -1l, -1m or -1q is selected, a 250 MHz optional frequency is not
supported. The only supported frequencies are 62.5 MHz and 125 MHz.
AXI Interface Width
The 7 Series FPGAs Integrated Block for PCI Express allows the selection of interface width,
as defined in Table 4-4. The default interface width is the lowest possible interface width.
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Table 4-4:
Lane Width, Link Speed, and Interface Width
Lane Width
Link Speed
(Gb/s)
Interface Width (Bits)
X1
2.5, 5.0
64
X2
2.5, 5.0
64
X4
2.5
64
X4
5.0
64, 128
X8
2.5
64, 128
X8
5.0
128
Reference Clock Frequency
Selects the frequency of the reference clock provided on sys_clk. For information about
clocking the core, see Clocking and Resets in Chapter 3.
Tandem Configuration
The radio buttons, None, Tandem PROM and Tandem PCIe, allow you to choose the Tandem
Configuration. The devices supported are K325T, K410T, K420T, V485T, and K160T. For Zynq
7Z030, 7Z045 and 7Z100 devices, only the Tandem PROM option is available. They do not
support Tandem PCIe mode.
PIPE Mode Simulations
This group box provides two radio buttons to select either of two PIPE mode simulation
mechanisms. This option is enabled for both Endpoint and Root Port configurations only
when the Shared Logic (clocking) in example design option is selected (see Shared
Logic, page 232).
•
None: No PIPE mode simulation is available. This is the default value.
•
Enable Pipe Simulation: When selected, this option generates the core that can be
simulated with PIPE interfaces connected.
•
Enable External PIPE Interface: When selected, this option enables an external
third-party bus functional model (BFM) to connect to the PIPE interface of the
Integrated Block for PCIe. This feature has been tested only with BFM from Avery
Design Systems (XAPP1184 [Ref 21]). For more information, see PIPE Mode Simulations,
page 260.
Enable External GT Channel DRP
The external GT channel DRP ports are pulled out to the core top.
•
ext_ch_gt_drpdo[15:0]
•
ext_ch_gt_drpdi[15:0]
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•
ext_ch_gt_drpen[0:0]
•
ext_ch_gt_drwe[0:0]
•
ext_ch_gt_drprdy[:0]
•
ext_ch_gt_drpaddr[8:0]
gt_ch_drp_rdy indicates that external GT channel DRP is ready to use and not in use by
internal logic.
Enable External Startup Primitive
This option enables the STARTUP primitive. By default, this parameter is currently disabled.
Additional Transceiver Control and Status Ports
Ports are described in Additional Transceiver Control and Status Ports in Appendix B.
Identifiers (IDs)
The IDs page shown in Figure 4-2 is used to customize the IP initial values, class code, and
Cardbus CIS pointer information.
X-Ref Target - Figure 4-2
Figure 4-2:
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ID Initial Values
•
Vendor ID: Identifies the manufacturer of the device or application. Valid identifiers
are assigned by the PCI Special Interest Group to guarantee that each identifier is
unique. The default value, 10EEh, is the Vendor ID for Xilinx. Enter a vendor
identification number here. FFFFh is reserved.
•
Device ID: A unique identifier for the application; the default value, which depends on
the configuration selected, is 70<link speed><link width>h. This field can be any value;
change this value for the application.
•
Revision ID: Indicates the revision of the device or application; an extension of the
Device ID. The default value is 00h; enter values appropriate for the application.
•
Subsystem Vendor ID: Further qualifies the manufacturer of the device or application.
Enter a Subsystem Vendor ID here; the default value is 10EE. Typically, this value is the
same as Vendor ID. Setting the value to 0000h can cause compliance testing issues.
•
Subsystem ID: Further qualifies the manufacturer of the device or application. This
value is typically the same as the Device ID; the default value depends on the lane
width and link speed selected. Setting the value to 0000h can cause compliance testing
issues.
Class Code
The Class Code identifies the general function of a device, and is divided into three
byte-size fields:
•
Base Class: Broadly identifies the type of function performed by the device.
•
Sub-Class: More specifically identifies the device function.
•
Interface: Defines a specific register-level programming interface, if any, allowing
device-independent software to interface with the device.
Class code encoding can be found at www.pcisig.com.
Class Code Look-up Assistant
The Class Code Look-up Assistant provides the Base Class, Sub-Class and Interface values
for a selected general function of a device. This Look-up Assistant tool only displays the
three values for a selected function. You must enter the values in Class Code for these
values to be translated into device settings.
Cardbus CIS Pointer
Used in cardbus systems and points to the Card Information Structure for the cardbus card.
If this field is non-zero, an appropriate Card Information Structure must exist in the correct
location. The default value is 0000_0000h; the value range is 0000_0000h-FFFF_FFFFh.
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Chapter 4: Design Flow Steps
Base Address Registers (BARs)
The Base Address Register (BAR) page shown in Figure 4-3 sets the base address register
space for the Endpoint configuration. Each BAR (0 through 5) represents a 32-bit parameter.
X-Ref Target - Figure 4-3
Figure 4-3:
BAR Parameters
Base Address Register Overview
The 7 Series FPGAs Integrated Block for PCI Express in Endpoint configuration supports up
to six 32-bit BARs or three 64-bit BARs, and the Expansion ROM BAR. The 7 Series FPGAs
Integrated Block for PCI Express in Root Port configuration supports up to two 32-bit BARs
or one 64-bit BAR, and the Expansion ROM BAR.
BARs can be one of two sizes:
•
32-bit BARs: The address space can be as small as 128 bytes or as large as 2 gigabytes.
Used for Memory to I/O.
•
64-bit BARs: The address space can be as small as 128 bytes or as large as 8 exabytes.
Used for Memory only.
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All BAR registers share these options:
•
Checkbox: Click the checkbox to enable the BAR; deselect the checkbox to disable the
BAR.
•
Type: BARs can either be I/O or Memory.
°
°
•
I/O: I/O BARs can only be 32-bit; the Prefetchable option does not apply to I/O
BARs. I/O BARs are only enabled for the Legacy PCI Express Endpoint core.
Memory: Memory BARs can be either 64-bit or 32-bit and can be prefetchable.
When a BAR is set as 64 bits, it uses the next BAR for the extended address space
and makes the next BAR inaccessible to you.
Size: The available Size range depends on the PCIe® Device/Port Type and the Type of
BAR selected. Table 4-5 lists the available BAR size ranges.
Table 4-5:
BAR Size Ranges for Device Configuration
PCIe Device / Port Type
PCI Express Endpoint
Legacy PCI Express Endpoint
BAR Type
BAR Size Range
32-bit Memory
128 Bytes – 2 Gigabytes
64-bit Memory
128 Bytes – 8 Exabytes
32-bit Memory
16 Bytes – 2 Gigabytes
64-bit Memory
16 Bytes – 8 Exabytes
I/O
16 Bytes – 2 Gigabytes
•
Prefetchable: Identifies the ability of the memory space to be prefetched.
•
Value: The value assigned to the BAR based on the current selections.
For more information about managing the Base Address Register settings, see Managing
Base Address Register Settings.
Expansion ROM Base Address Register
If selected, the Expansion ROM is activated and can be a value from 2 KB to 4 GB. According
to the PCI 3.0 Local Bus Specification [Ref 2], the maximum size for the Expansion ROM BAR
should be no larger than 16 MB. Selecting an address space larger than 16 MB might result
in a non-compliant core.
Managing Base Address Register Settings
Memory, I/O, Type, and Prefetchable settings are handled by setting the appropriate
settings for the desired base address register.
Memory or I/O settings indicate whether the address space is defined as memory or I/O.
The base address register only responds to commands that access the specified address
space. Generally, memory spaces less than 4 KB in size should be avoided. The minimum I/
O space allowed is 16 bytes; use of I/O space should be avoided in all new designs.
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Prefetchability is the ability of memory space to be prefetched. A memory space is
prefetchable if there are no side effects on reads (that is, data is not destroyed by reading,
as from a RAM). Byte write operations can be merged into a single double word write, when
applicable.
When configuring the core as an Endpoint for PCIe (non-Legacy), 64-bit addressing must be
supported for all BARs (except BAR5) that have the prefetchable bit set. 32-bit addressing
is permitted for all BARs that do not have the prefetchable bit set. The prefetchable bit
related requirement does not apply to a Legacy Endpoint. The minimum memory address
range supported by a BAR is 128 bytes for a PCI Express Endpoint and 16 bytes for a Legacy
PCI Express Endpoint.
Disabling Unused Resources
For best results, disable unused base address registers to conserve system resources. A base
address register is disabled when unused BARs are deselected.
Core Capabilities
The Core Capabilities parameters shown in Figure 4-4 is used to customize the IP initial
values, class code, and Cardbus CIS pointer information.
X-Ref Target - Figure 4-4
Figure 4-4:
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Capabilities Register
•
Capability Version: Indicates the PCI-SIG® defined PCI Express capability structure
version number; this value cannot be changed.
•
Device Port Type: Indicates the PCI Express logical device type.
•
Slot Implemented: Indicates the PCI Express Link associated with this port is
connected to a slot. Only valid for a Root Port of a PCI Express Root Complex or a
Downstream Port of a PCI Express Switch.
•
Capabilities Register: Displays the value of the Capabilities register presented by the
integrated block, and is not editable.
Device Capabilities Register
•
Max Payload Size: Indicates the maximum payload size that the device/function can
support for transaction layer packets (TLPs).
•
Device Capabilities Register: Displays the value of the Device Capabilities register
presented by the integrated block and is not editable.
Block RAM Configuration Options
•
Buffering Optimized for Bus Mastering Applications: Causes the device to advertise
to its Link Partner credit settings that are optimized for Bus Mastering applications.
•
Performance Level: Selects the Performance Level settings, which determines the
Receiver and Transmitter Sizes. The table displayed specifies the Receiver and
Transmitter settings - number of TLPs buffered in the Transmitter, the Receiver Size, the
Credits advertised by the Core to the Link Partner and the Number of Block RAMs
required for the configuration, corresponding to the Max Payload Size selected, for
each of the Performance Level options.
•
Finite Completions: If selected, causes the device to advertise to the Link Partner the
actual amount of space available for Completions in the Receiver. For an Endpoint, this
is not compliant to the PCI Express Base Specification, rev. 2.1, as Endpoints are required
to advertise an infinite amount of completion space.
Device Capabilities 2 Register
This section sets the Device Capabilities 2 register.
•
Completion Timeout Disable Supported: Indicates support for Completion Timeout
Disable mechanism
•
Completion Timeout Ranges Supported: Indicates Device Function support for the
optional Completion Timeout mechanism.
RECOMMENDED: Do not let the Completion Timeout mechanism expire in less than 10 ms.
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Chapter 4: Design Flow Steps
•
Device Capabilities2 Register: Displays the value of the Device Capabilities2 Register
sent to the Core and is not editable.
Interrupts
The Interrupt parameters in Figure 4-5 sets the Legacy Interrupt Settings, and MSI
Capabilities.
X-Ref Target - Figure 4-5
Figure 4-5:
Interrupts Capabilities
Legacy Interrupt Settings
•
Enable INTX: Enables the ability of the PCI Express function to generate INTx
interrupts.
•
Interrupt PIN: Indicates the mapping for Legacy Interrupt messages. A setting of
“None” indicates no Legacy Interrupts are used.
Note: Only INT A is supported.
MSI Capabilities
•
Enable MSI Capability Structure: Indicates that the MSI Capability structure exists.
•
64 bit Address Capable: Indicates that the function is capable of sending a 64-bit
Message Address.
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Chapter 4: Design Flow Steps
•
Multiple Message Capable: Selects the number of MSI vectors to request from the
Root Complex.
•
Per Vector Masking Capable: Indicates that the function supports MSI per-vector
Masking.
Advanced Mode
The Advanced mode parameters are explained in this section.
Basic
The Basic parameters for Advanced mode, shown in Figure 4-6, is same as those for Base
mode with the addition of the PCIe DRP Ports parameter. For a description of the Base mode
parameters, see Basic, page 205.
•
PCIe DRP Ports: Checking this box enables the generation of DRP ports for the PCIe
Hard Block, giving you dynamic control over the PCIe Hard Block attributes. This
setting can be used to perform advanced debugging. Any modifications to the PCIe
default attributes must be made only if directed by Xilinx Technical Support (see
Contacting Xilinx Technical Support, page 330).
X-Ref Target - Figure 4-6
Figure 4-6:
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Basic Parameters (Advanced mode)
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Identifiers (IDs)
The parameters for Advanced mode are the same as those for Basic mode. See Identifiers
(IDs), page 209.
Base Address Registers (BARs)
The parameters for Advanced mode are the same as those for Basic mode. See Base Address
Registers (BARs), page 211.
Core Capabilities
The Core Capabilities parameters in Advanced mode, shown in Figure 4-7, are same as
those in Basic mode, with the addition of the following parameters. For a description of the
Basic mode parameters, see Core Capabilities, page 217.
X-Ref Target - Figure 4-7
Figure 4-7:
Core Capabilities (Advanced Mode)
Device Capabilities Register
•
Extended Tag Field: Indicates the maximum supported size of the Tag field as a
Requester. When selected, indicates 8-bit Tag field support. When deselected, indicates
5-bit Tag field support.
•
Extended Tag Default: When this field is checked, indicates the default value of bit 8
of the Device Control register is set to 1 to support the Extended Tag Enable Default
ECN.
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•
Phantom Functions: Indicates the support for use of unclaimed function numbers to
extend the number of outstanding transactions allowed by logically combining
unclaimed function numbers (called Phantom Functions) with the Tag identifier. See
Section 2.2.6.2 of the PCI Express Base Specification, rev. 2.1 [Ref 2] for a description of
Tag Extensions. This field indicates the number of most significant bits of the function
number portion of Requester ID that are logically combined with the Tag identifier.
•
Acceptable L0s Latency: Indicates the acceptable total latency that an Endpoint can
withstand due to the transition from L0s state to the L0 state.
•
Acceptable L1 Latency: Indicates the acceptable latency that an Endpoint can
withstand due to the transition from L1 state to the L0 state.
Device Capabilities Register
•
UR Atomic: If checked, the core automatically responds to Atomic Operation requests
with an Unsupported Request. If unchecked, the core passes Atomic Operations TLPs to
the user.
•
32-bit AtomicOp Completer Support: Indicates 32-bit AtomicOp Completer support.
•
64-bit AtomicOp Completer Support: Indicates 64-bit AtomicOp Completer support.
•
128-bit CAS Completer Support: Indicates 128-bit Compare And Swap completer
support.
•
TPH Completer Supported: Indicates the level of support for TPH completer.
Link Registers
The Link Registers page is available only when in Advanced mode.
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Chapter 4: Design Flow Steps
X-Ref Target - Figure 4-8
Figure 4-8:
Link Registers (Advanced Mode)
Link Capabilities Register
This section sets the Link Capabilities register.
•
Supported Link Speed: Indicates the supported link speed of the given PCI Express
Link. This value is set to the Link Speed specified in the Basic tab and is not editable.
•
Maximum Link Width: This value is set to the initial lane width specified in the Basic
tab and is not editable.
•
ASPM Optionality: When checked, this field enables ASPM optionally.
•
DLL Link Active Reporting Capability: Indicates the optional Capability of reporting
the DL_Active state of the Data Link Control and Management State Machine.
•
Link Capabilities Register: Displays the value of the Link Capabilities register sent to
the core and is not editable.
Link Control Register
•
Hardware Autonomous Speed Disable: When checked, this field disables the
hardware from changing the link speed for device specific reasons other than
attempting to correct unreliable link operation by reducing link speed.
•
Read Completion Boundary: Indicates the Read Completion Boundary for the Root
Port.
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•
Target Link Speed: Sets an upper limit on the link operational speed. This is used to
set the target Compliance Mode speed. The value is set to the supported link speed
and can be edited only if the link speed is set to 5.0 Gb/s.
•
Compliance De-emphasis: Sets the level of de-emphasis for an Upstream component,
when the Link is operating at 5.0 Gb/s. This feature is not editable.
•
Link Control Register 1: Displays the value of the Link Control Register sent to the
core and is not editable.
•
Link Control Register 2: Displays the value of the Link Control 2 Register sent to the
core and is not editable.
Link Status Register
•
Enable Slot Clock Configuration: Indicates that the Endpoint uses the
platform-provided physical reference clock available on the connector. Must be cleared
if the Endpoint uses an independent reference clock.
Configuration Register (Only in Root Port Configuration)
The Configuration Register pages isavailable only when Root Port configuration is selected,
and when in Advanced mode.
X-Ref Target - Figure 4-9
Figure 4-9:
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IMPORTANT: These settings are valid for Root Port configurations only.
Root Capabilities Register
•
CRS Software Visibility: Indicates the Root Port capability of returning the CRs to
software. When set, indicates that the Root Port can return the Configuration Request
Retry Status (CRS) completion status to software.
•
Root Capabilities Register: Specifies the Root Capabilities Register of the device.
Slot Control Capabilities Register
•
Attention Button Present: Indicates the Attention Button is implemented. When set,
indicates that an Attention Button for this slot is implemented on the chassis. This
option is disabled when “Device_Port_Type” is not “Root Port of PCI Express Root
Complex.” This is enabled only when the Slot Implemented parameter in the Core
Capabilities tab is selected (see Figure 4-4).
•
Attention Indicator Present: Indicates the Attention Indicator is implemented. When
set, indicates that an Attention Indicator for this slot is implemented on the chassis.
This option is disabled when “Device_Port_Type” is not “Root Port of PCI Express Root
Complex.” This is enabled only when the Slot Implemented parameter in the Core
Capabilities tab is selected (see Figure 4-4).
•
Power Controller Present: Indicates the Power Controller is implemented. When set,
indicates that a software programmable Power Controller is implemented for this slot.
This option is disabled when “Device_Port_Type” is not “Root Port of PCI Express Root
Complex.” This is enabled only when the Slot Implemented parameter in the Core
Capabilities tab is selected (see Figure 4-4).
•
Power Indicator Present: Indicates the Power Indicator is implemented. When set,
indicates that a Power Indicator is implemented on the chassis for this slot. This option
is disabled when “Device_Port_Type” is not “Root Port of PCI Express Root Complex.”
This is enabled only when the Slot Implemented parameter in the Core Capabilities tab
is selected (see Figure 4-4).
•
Hot-Plug Surprise: When set, indicates that an adapter in this slot might be removed
from the system without any prior notification. This option is disabled when
“Device_Port_Type” is not “Root Port of PCI Express Root Complex.” This is enabled only
when the Slot Implemented parameter in the Core Capabilities tab is selected (see
Figure 4-4).
•
Hot-Plug Capable: When set, indicates that this slot is capable of supporting hot-plug
operations. This option is disabled when "Device_Port_Type" is not “ Root Port of PCI
Express Root Complex.” This is enabled only when the Slot Implemented parameter in
the Core Capabilities tab is selected (see Figure 4-4).
•
MRL Sensor Present: Indicates MRL Sensor implemented. When Set, indicates that an
MRL (Manually operated Retention Latch) sensor is implemented for this slot, on the
chassis. This option is disabled when “Device_Port_Type” is not “Root Port of PCI
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Chapter 4: Design Flow Steps
Express Root Complex.” This is enabled only when the Slot Implemented parameter in
the Core Capabilities tab is selected (see Figure 4-4).
•
Electromechanical Interlock Present: When set, indicates that an Electromechanical
Interlock is implemented on the chassis for this slot. This option is disabled when
"Device_Port_Type" is not “Root Port of PCI Express Root Complex.” This is enabled only
when the Slot Implemented parameter in the Core Capabilities tab is selected (see
Figure 4-4).
•
No Command Completed Support: When set, indicates that the slot does not
generate software notification when an issue command is completed by the Hot-Plug
Controller. This option is disabled when "Device_Port_Type" is not “Root Port of PCI
Express Root Complex.” This is enabled only when the Slot Implemented parameter in
the Core Capabilities tab is selected (see Figure 4-4).
•
Slot Power Limit Value: Specifies the Upper Limit on power supplied to the slot, in
combination with Slot Power Limit Scale value. This option is disabled when
"Device_Port_Type" is not “Root Port of PCI Express Root Complex.” This is enabled only
when the Slot Implemented parameter in the Core Capabilities tab is selected (see
Figure 4-4).
•
Slot Power Limit Scale: Specifies the scale used for the Slot Power Limit value. This
option is disabled when "Device_Port_Type" is not “Root Port of PCI Express Root
Complex.” This is enabled only when the Slot Implemented parameter in the Core
Capabilities tab is selected (see Figure 4-4).
•
Physical Slot Number: Specifies the Physical Slot Number attached to this port. This
field must be hardware initialized to a value that assigns a slot number that is unique
within the chassis, regardless of form factor associated with the slot. This option is
disabled when "Device_Port_Type" is not “Root Port of PCI Express Root Complex.” This
is enabled only when the Slot Implemented parameter in the Core Capabilities tab is
selected (see Figure 4-4).
•
Slot Capabilities Register. Specifies the Slot Capabilities Register of the device.
Interrupts
The Interrupts parameters in Advanced mode are the same as those in Basic mode, with the
addition of MSIx Capabilities. For a description of the Basic mode parameters, see
Interrupts, page 215.
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X-Ref Target - Figure 4-10
Figure 4-10:
Interrupts Parameters (Advanced Mode)
MSI-X Capabilities
•
Enable MSIx Capability Structure: Indicates that the MSI-X Capability structure exists.
Note: This Capability Structure needs at least one Memory BAR to be configured.
•
MSIx Table Settings: Defines the MSI-X Table Structure.
°
Table Size: Specifies the MSI-X Table Size.
°
Table Offset: Specifies the Offset from the Base Address Register that points to the
Base of the MSI-X Table.
°
•
BAR Indicator: Indicates the Base Address Register in the Configuration Space that
is used to map the functions MSI-X Table, onto Memory Space. For a 64-bit Base
Address Register, this indicates the lower DWORD.
MSIx Pending Bit Array (PBA) Settings: Defines the MSI-X Pending Bit Array (PBA)
Structure.
°
PBA Offset: Specifies the Offset from the Base Address Register that points to the
Base of the MSI-X PBA.
°
PBA BAR Indicator: Indicates the Base Address Register in the Configuration Space
that is used to map the function MSI-X PBA onto Memory Space.
Power Management
The Power Management Registers page shown in Figure 4-11 includes settings for the
Power Management Registers, power consumption and power dissipation options.
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X-Ref Target - Figure 4-11
Figure 4-11:
Power Management Registers
•
Device Specific Initialization: This bit indicates whether special initialization of this
function is required (beyond the standard PCI configuration header) before the generic
class device driver is able to use it. When selected, this option indicates that the
function requires a device specific initialization sequence following transition to the D0
uninitialized state. See section 3.2.3 of the PCI Bus Power Management Interface
Specification Revision 1.2 [Ref 2].
•
D1 Support: When selected, this option indicates that the function supports the D1
Power Management State. See section 3.2.3 of the PCI Bus Power Management Interface
Specification Revision 1.2.
•
D2 Support: When selected, this option indicates that the function supports the D2
Power Management State. See section 3.2.3 of the PCI Bus Power Management Interface
Specification Revision 1.2.
•
PME Support From: When this option is selected, it indicates the power states in which
the function can assert cfg_pm_wake. See section 3.2.3 of the PCI Bus Power
Management Interface Specification Revision 1.2.
•
No Soft Reset: Checking this box indicates that if the device transitions from D3hot to
D0 because of a Power State Command, it does not perform an internal reset and
Configuration context is preserved. Disabling this option is not supported.
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Power Consumption
The 7 Series FPGAs Integrated Block for PCI Express always reports a power budget of 0W.
For information about power consumption, see section 3.2.6 of the PCI Bus Power
Management Interface Specification Revision 1.2.
Power Dissipated
The 7 Series FPGAs Integrated Block for PCI Express always reports a power dissipation of
0W. For information about power dissipation, see section 3.2.6 of the PCI Bus Power
Management Interface Specification Revision 1.2.
Extended Capabilities
The PCIe Extended Capabilities page shown in Figure 4-12 is available in Advanced mode
only, and includes settings for Device Serial Number Capability, Virtual Channel Capability,
Vendor Specific Capability, and optional user-defined Configuration capabilities.
X-Ref Target - Figure 4-12
Figure 4-12:
PCIe Extended Capabilities
Device Serial Number Capability
•
Device Serial Number Capability: An optional PCIe Extended Capability containing a
unique Device Serial Number. When this Capability is enabled, the DSN identifier must
be presented on the Device Serial Number input pin of the port. This Capability must
be turned on to enable the Virtual Channel and Vendor Specific Capabilities.
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Virtual Channel Capability
•
Virtual Channel Capability: An optional PCIe Extended Capability which allows the
user application to be operated in TCn/VC0 mode. Checking this allows Traffic Class
filtering to be supported.
•
Reject Snoop Transactions (Root Port Configuration Only): When enabled, any
transactions for which the No Snoop attribute is applicable, but is not set in the TLP
header, can be rejected as an Unsupported Request.
Vendor Specific Capability
•
Vendor Specific Capability: An optional PCIe Extended Capability that allows PCI
Express component vendors to expose Vendor Specific Registers. When checked,
enables Xilinx specific Loopback Control.
User-Defined Configuration Capabilities: Endpoint Configuration Only
•
PCI Configuration Space Enable: Allows the user application to add/implement PCI
Legacy capability registers. This option should be selected if the user application
implements a legacy capability configuration space. This option enables the routing of
Configuration Requests to addresses outside the built-in PCI-Compatible Configuration
Space address range to the AXI4-Stream interface.
•
PCI Configuration Space Pointer: Sets the starting Dword aligned address of the
user-definable PCI Compatible Configuration Space. The available DWORD address
range is 2Ah - 3Fh.
•
PCI Express Extended Configuration Space Enable: Allows the user application to
add/implement PCI Express Extended capability registers. This option should be
selected if the user application implements such an extended capability configuration
space. This enables the routing of Configuration Requests to addresses outside the
built-in PCI Express Extended Configuration Space address range to the user
application.
•
PCI Configuration Space Pointer: Sets the starting DWORD aligned address of the PCI
Express Extended Configuration Space implemented by the user application. This
action enables routing of Configuration Requests with DWORD addresses greater than
or equal to the value set in the user application. The available address range depends
on the PCIe Extended Capabilities selected. For more information, see Chapter 3,
Designing with the Core.
Extended Capabilities 2
The Extended Capabilities 2 page is available only when in Advanced mode.
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X-Ref Target - Figure 4-13
Figure 4-13:
PCIe Extended Capabilities: AER Capability
AER Capability
•
Enable AER Capability: An optional PCIe Extended Capability that allows Advanced
Error Reporting.
•
Multiheader: Indicates support for multiple-header buffering for the AER header log
field. (Not supported for the 7 Series FPGAs Integrated Block for PCI Express.)
•
Permit Root Error Update: If TRUE, permits the AER Root Status and Error Source ID
registers to be updated. If FALSE, these registers are forced to 0.
•
ECRC Check Capable: Indicates the core can check ECRC.
•
Optional Error Support: Indicates which option error conditions in the Uncorrectable
and Correctable Error Mask/Severity registers are supported. If an error box is
unchecked, the corresponding bit in the Mask/Severity register is hardwired to 0.
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Chapter 4: Design Flow Steps
X-Ref Target - Figure 4-14
Figure 4-14:
PCIe Extended Capabilities: RBAR Capabilities
RBAR Capabilities
•
Enable RBAR Capability: An optional PCIe Extended Capability that allows Resizable
BARs.
•
Number of RBARs: Number of resizeable BARs in the Cap Structure, which depends on
the number of BARs enabled.
•
BARn Size Supported: RBAR Size Supported vector for RBAR Capability Register (0
through 5)
•
BARn Index Value: Sets the index of the resizeable BAR from among the enabled BARs
•
RBARn Init Value: RBAR Initial Value for the RBAR Control BAR Size field.
X-Ref Target - Figure 4-15
Figure 4-15:
PCIe Extended Capabilities: ECRC
ECRC
•
Receive ECRC Check: Enables ECRC checking of received TLPs.
°
0 = Do not check
°
1 = Always check
°
3 = Check if enabled by the ECRC check enable bit of the AER Capability Structure
•
Trim TLP Digest: Enables TD bit clear and ECRC trim on received TLPs.
•
Disable RX Poisoned Resp: Disables the core from sending a message and setting
status bits due to receiving a Poisoned TLP. The behavior of the core when the Disable
RX poisoned Resp is checked is as follows.
°
When Advisory Non-Fatal Error Mask: 1 (default). When the core Receives a
poisoned CfgWr, it sets Parity Error and sends completion with UR. When it receives
poisoned MemWr, it sets the Parity error and no TLP is sent.
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°
Advisory Non-Fatal Error Mask: 0. When DISABLE_RX_POISONED_RESP is set to
FALSE and a poisoned MemWr is received, the core sends an error message
automatically. When DISABLE_RX_POISONED_RESP is set to TRUE and a poisoned
MemWr is received, an error message is not transmitted. When you assert
cfg_err_poisoned, the core sends the error message.
TL Settings
The Transaction Layer (TL) Settings page is available only when in Advanced mode.
X-Ref Target - Figure 4-16
Figure 4-16:
TL Settings
Transaction Layer Module
•
Enable Message Routing: Controls if message TLPs are also received on the
AXI4-Stream interface.
•
Endpoint:
°
•
Unlock and PME_Turn_Off Messages
Root Port:
°
Error Messages - Error Correctable, Error Non-Fatal, Error Fatal
°
Assert/Deassert INT Messages - INTA, INTB, INTC, INTD
°
Power Management Messages - PM_PME, PME_TO_ACK
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Chapter 4: Design Flow Steps
•
Receive Non-Posted Request (Non-Posted Flow Control)
°
The rx_np_req signal prevents the user application from buffering Non-Posted
TLPs. When rx_np_req is asserted, one Non-Posted TLP is requested from the
integrated block. This signal cannot be used in conjunction with rx_np_ok. Every
time that rx_np_req is asserted, one TLP is presented on the receive interface;
whereas, every time that rx_np_ok is deasserted, the user application needs to
buffer up to two additional Non-Posted TLPs.
•
Pipeline Registers for Transaction Block RAM Buffers: Selects the Pipeline registers
enabled for the Transaction Buffers. Pipeline registers can be enabled on either the
Write path or both the Read and Write paths of the Transaction Block RAM buffers.
•
ATS
°
°
UR_INV_REQ: When this box is checked, the core handles received ATS Invalidate
request messages as unsupported requests. When this box is unchecked, the core
passes received ATS Invalidate request messages.
UR_PRS_RESPONSE: When this box is checked, the core handles received ATS Page
Request Group Response messages as unsupported requests. When this box is
unchecked, the core passes received ATS PRG Response messages.
DL and PL Settings
The DL and PL Settings page is available only when in Advanced mode.
X-Ref Target - Figure 4-17
Figure 4-17:
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Chapter 4: Design Flow Steps
Link Layer Module
•
Override ACK/NAK Latency Timer: Checking this box enables you to override the
ACK/NAK latency timer values set in the device. Using this feature can cause the ACK
timeout values to be non-compliant to the PCI Express Base Specification, rev. 2.1
[Ref 2]. This setting can be used to perform advanced debugging operations.
CAUTION! Modify the default attributes only if directed by Xilinx Technical Support.
•
ACK Latency Timer Override Function: This setting determines how the override
value is used by the device with respect to the ACK/NAK Latency Timer Value in the
device. Options are “Absolute”, “Add”, and “Subtract”. The first two settings can cause
the ACK timeout values to be non-compliant with the PCI Express Base Specification, rev.
2.1.
•
ACK Latency Timer Override Value: This setting determines the ACK/NAK latency
timer value used by the device depending on if the ACK Latency Timer Override
Function enabled. The built-in table value depends on the Negotiated Link Width and
Programmed MPS of the device.
•
Override Replay Timer: Checking this box enables you to override the replay timer
values set in the device. Use of this feature could cause the replay timeout values to be
non-compliant to the PCI Express Base Specification, rev. 2.1. This setting can be used to
perform advanced debugging operations.
CAUTION! Modify the default attributes only if directed by Xilinx Technical Support.
•
Replay Timer Override Function: This setting determines how the override value is
used by the device with respect to the replay timer value in the device. Options are
“Absolute”, “Add”, and “Subtract”. The first two settings can cause the replay timeout
values to be non-compliant with the PCI Express Base Specification, rev. 2.1.
•
Replay Timer Override Value: This setting determines the replay timer value used by
the device depending on if the Replay Timer Override Function enabled. The built-in
table value depends on the Negotiated Link Width and Programmed MPS of the device.
IMPORTANT: You must ensure that the final timeout value does not overflow the 15-bit timeout value.
Advanced Physical Layer
•
Enable Lane Reversal: When checked, enables the Lane Reversal feature.
•
Force No Scrambling: Used for diagnostic purposes only and should never be enabled
in a working design. Setting this bit results in the data scramblers being turned off so
that the serial data stream can be analyzed.
•
Upconfigure Capable: When unchecked, the port is advertised as “Not Upconfigure
Capable” during Link Training.
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Chapter 4: Design Flow Steps
•
Disable TX ASPM L0s: When checked, prevents the device transmitter from entering
the L0s state.
RECOMMENDED: Disable TX ASPM L0s for a link that interconnects a 7 series FPGA to any Xilinx
component.
•
Link Number: Specifies the link number advertised by the device in TS1 and TS2
ordered sets during Link training. Used in downstream facing mode only.
Shared Logic
Enables you to share common blocks across multiple instantiations by selecting one or
more of the options on this page. For a details description of the shared logic feature, see
Shared Logic in Chapter 3.
Core Interface Parameters
You can select the core interface parameters to use. By default all ports are brought out. For
cases you might choose to disable some of the interfaces if they are not used. When
disabled, the interfaces (ports) are removed from the core top.
RECOMMENDED: For a typical use case, do not disable the interfaces. Disable the ports only in special
cases.
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X-Ref Target - Figure 4-18
Figure 4-18:
Core Interface Parameters
PL Interface
When you disable the physical layer (PL) Interface option, the following ports are removed
from the core. This option enables you to inspect the status of the link and link partner and
control the link state
•
pl_sel_lnk_rate
•
pl_sel_lnk_width
•
pl_ltssm_state
•
pl_lane_reversal_mode
•
pl_phy_lnk_up
•
pl_directed_link_change
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•
pl_directed_link_width
•
pl_directed_link_speed
•
pl_directed_link_auton
•
pl_tx_pm_state
•
pl_rx_pm_state
•
pl_link_upcfg_cap
•
pl_link_gen2_cap
•
pl_link_partner_gen2_supported
•
pl_initial_link_width
•
pl_upstream_prefer_deemph
•
pl_downstream_deemph_source
•
pl_directed_change_done
•
pl_transmit_hot_rst
•
pl_received_hot_rst
Error Reporting
When you disable the Error Reporting option, the following ports are removed from the
core. These signals are associated with the user application error reporting interface for the
PCIe Gen2 core.
•
cfg_err_malformed
•
cfg_err_cor
•
cfg_err_ur
•
cfg_err_ecrc
•
cfg_err_cpl_timeout
•
cfg_err_cpl_abort
•
cfg_err_cpl_unexpect
•
cfg_err_poisoned
•
cfg_err_acs
•
cfg_err_atomic_egress_blocked
•
cfg_err_mc_blocked
•
cfg_err_internal_uncor
•
cfg_err_internal_cor
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Chapter 4: Design Flow Steps
•
cfg_err_posted
•
cfg_err_locked
•
cfg_err_norecovery
•
cfg_err_cpl_rdy
•
cfg_err_tlp_cpl_header
•
cfg_err_aer_headerlog
•
cfg_aer_interrupt_msgnum
•
cfg_err_aer_headerlog_set
•
cfg_aer_ecrc_check_en
•
cfg_aer_ecrc_gen_en
Config Management Interface
When you disable the Config Management Interface option, the following ports are
removed from the port. These signals are used to read and write to the Configuration Space
registers.
•
cfg_mgmt_do
•
cfg_mgmt_di
•
cfg_mgmt_byte_en
•
cfg_mgmt_dwaddr
•
cfg_mgmt_wr_rw1c_as_rw
•
cfg_mgmt_wr_readonly
•
cfg_mgmt_wr_en
•
cfg_mgmt_rd_en
•
cfg_mgmt_rd_wr_done
Config CTRL Interface
When you disable the Config Control (CTRL) Interface option, the following ports are
removed from the core. These signals allow a broad range of information exchange
between the user application and the core.
•
cfg_trn_pending
•
cfg_pm_halt_aspm_l0s
•
cfg_pm_halt_aspm_l1
•
cfg_pm_force_state_en
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Chapter 4: Design Flow Steps
•
cfg_pm_force_state
•
cfg_dsn
•
tx_cfg_gnt
•
rx_np_ok
•
rx_np_req
•
cfg_turnoff_ok
•
cfg_pm_wake
•
cfg_pm_send_pme_to
•
cfg_ds_bus_number
•
cfg_ds_device_number
•
cfg_ds_function_number
Config Status Interface
When you disable the Config Status Interface, the following ports are removed from the
core. These signals provide information on how the PCIe Gen2 core is configured.
•
cfg_status
•
cfg_command
•
cfg_dstatus
•
cfg_dcommand
•
cfg_lstatus
•
cfg_lcommand
•
cfg_dcommand2
•
cfg_pcie_link_state
•
cfg_pmcsr_powerstate
•
cfg_pmcsr_pme_en
•
cfg_pmcsr_pme_status
•
cfg_received_func_lvl_rst
•
cfg_to_turnoff
•
cfg_bus_number
•
cfg_device_number
•
cfg_function_number
•
cfg_bridge_serr_en
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Chapter 4: Design Flow Steps
•
•
cfg_slot_control_electromech_il_ctl_pulse
cfg_root_control_syserr_corr_err_en
•
cfg_root_control_syserr_non_fatal_err_en
•
cfg_root_control_syserr_fatal_err_en
•
cfg_root_control_pme_int_en
•
cfg_aer_rooterr_corr_err_reporting_en
•
cfg_aer_rooterr_non_fatal_err_reporting_en
•
cfg_aer_rooterr_fatal_err_reporting_en
•
cfg_aer_rooterr_corr_err_received
•
cfg_aer_rooterr_non_fatal_err_received
•
cfg_aer_rooterr_fatal_err_received
•
cfg_vc_tcvc_map
•
tx_buf_av
•
tx_err_drop
•
tx_cfg_req
Receive Msg Interface
When you disable the Receive Message Interface option, the following ports are removed
from the core. These signals indicate decodable messages from the link, parameters
associated with the data, and type of message received.
•
cfg_msg_received
•
cfg_msg_data
•
cfg_msg_received_err_cor
•
cfg_msg_received_err_non_fatal
•
cfg_msg_received_err_fatal
•
cfg_msg_received_assert_int_a
•
cfg_msg_received_deassert_int_a
•
cfg_msg_received_assert_int_b
•
cfg_msg_received_deassert_int_b
•
cfg_msg_received_assert_int_c
•
cfg_msg_received_deassert_int_c
•
cfg_msg_received_assert_int_d
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Chapter 4: Design Flow Steps
•
cfg_msg_received_deassert_int_d
•
cfg_msg_received_pm_pme
•
cfg_msg_received_pme_to_ack
•
cfg_msg_received_unlock
•
cfg_msg_received_pm_as_nak
Config FC Interface
When you disable the Config flow control (FC) Interface option, the following ports are
removed from the core. These signals are associated with the configuration flow control for the
PCIe Gen2 Core.
•
cfg_fc_ph
•
cfg_fc_pd
•
cfg_fc_nph
•
cfg_fc_npd
•
cfg_fc_cplh
•
cfg_fc_cpld
•
cfg_fc_sel
Output Generation
For details, see the Vivado Design Suite User Guide: Designing with IP (UG896) [Ref 15].
Endpoint Configuration
This section shows the directory structure for the Endpoint configuration of the generated
core. See Chapter 5, Detailed Example Designs for descriptions of the contents of each
directory.
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Chapter 4: Design Flow Steps
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Root Port Configuration
This section shows the directory structure for the Root Port configuration of the generated
core. See Chapter 5, Detailed Example Designs for descriptions of the contents of each
directory.
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Chapter 4: Design Flow Steps
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Constraining the Core
The 7 Series FPGAs Integrated Block for PCI Express solution requires the specification of
timing and other physical implementation constraints to meet specified performance
requirements for PCI Express. These constraints are provided with the Endpoint and Root
Port solutions in a Xilinx Design Constraints (XDC) file. Pinouts and hierarchy names in the
generated XDC correspond to the provided example design.
TIP: To achieve consistent implementation results, use an XDC file containing these original,
unmodified constraints when a design is run through the Xilinx tools. For additional details on the
definition and use of an XDC file or specific constraints, see the Vivado Design Suite Tcl Command
Reference Guide (UG835) [Ref 20].
Constraints provided with the integrated block solution have been tested in hardware and
provide consistent results. Constraints can be modified, but modifications should only be
made with a thorough understanding of the effect of each constraint. Additionally, support
is not provided for designs that deviate from the provided constraints.
Although the XDC file delivered with each core shares the same overall structure and
sequence of information, the content of the XDC for each core varies. The sections that
follow define the structure and sequence of information in a generic XDC.
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Chapter 4: Design Flow Steps
Device, Package, and Speed Grade Selections
The first section of the XDC specifies the exact device for the implementation tools to
target, including the specific part, package, and speed grade. In some cases, device-specific
options can be included. The device in the XDC reflects the device chosen in the Vivado
Design Suite project.
User Timing Constraints
The user timing constraints section is not populated. It is a placeholder for you to provide
timing constraints on user-implemented logic.
User Physical Constraints
The user physical constraints section is not populated. It is a placeholder for you to provide
physical constraints on user-implemented logic.
Core Pinout and I/O Constraints
The core pinout and I/O constraints section contains constraints for I/Os belonging to the
core System (SYS) and PCI Express (PCI_EXP) interfaces. It includes location constraints for
pins, I/O logic and I/O standard constraints.
Core Physical Constraints
The core physical constraints are used to limit the core to a specific area of the device and
to specify locations for clock buffering and other logic instantiated by the core.
Core Timing Constraints
This core timing constraints section defines clock frequency requirements for the core and
specifies which nets the timing analysis tool should ignore.
Device Selection
The device selection portion of the XDC informs the implementation tools which part,
package, and speed grade to target for the design.
IMPORTANT: Because the core is designed for specific part and package combinations, do not modify
this section.
The device selection section always contains a part selection line, but can also contain part
or package-specific options. An example part selection line:
CONFIG PART = XC7V585T-FFG1761-1
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Core I/O Assignments
This section controls the placement and options for I/Os belonging to the core System (SYS)
interface and PCI Express (PCI_EXP) interface. set_property constraints in this section
control the pin location and I/O options for signals in the SYS group. Locations and options
vary depending on which derivative of the core is used and should not be changed without
fully understanding the system requirements.
For example:
set_property IOSTANDARD LVCMOS18 [get_ports sys_rst_n]
set_property LOC IBUFDS_GTE2_X0Y3 [get_cells refclk_ibuf]
See Clocking and Resets in Chapter 3 for detailed information about reset and clock
requirements.
For GTX transceiver pinout information, see the “Placement Information by Package”
appendix in the 7 Series FPGAs GTX/GTH Transceivers User Guide (UG476) [Ref 12].
INST constraints are used to control placement of signals that belong to the PCI_EXP group.
These constraints control the location of the transceiver(s) used, which implicitly controls
pin locations for the transmit and receive differential pair.
For example:
set_property LOC GTXE2_CHANNEL_X0Y7 [get_cells {pcie_7x_v2_1_0_i/inst/inst/gt_top_i/
pipe_wrapper_i/pipe_lane[0].gt_wrapper_i/gtx_channel.gtxe2_channel_i}]
Core Physical Constraints
Core physical constraints are included in the constraints file to control the location of
clocking and other elements and to limit the core to a specific area of the FPGA logic.
IMPORTANT: Specific physical constraints are chosen to match each supported device and package
combination. Do not modify these constraints.
Note: In certain situations where a design cannot close timing, the following AREA_GROUP
constraints can be added to XDC.
INST "core/*" AREA_GROUP = "AG_core" ;
AREA_GROUP "AG_core"
RANGE = SLICE_X136Y147:SLICE_X155Y120 ;
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Chapter 4: Design Flow Steps
Core Timing Constraints
Timing constraints are provided for all integrated block solutions, although they differ
based on core configuration. In all cases, they are crucial and must not be modified, except
to specify the top-level hierarchical name. Timing constraints are divided into two
categories:
•
set_false_path constraints. Used on paths where specific delays are unimportant, to
instruct the timing analysis tools to refrain from issuing Unconstrained Path warnings.
•
Frequency constraints. Group clock nets into time groups and assign properties and
requirements to those groups.
Here is an example of a set_false_path constraint:
set_false_path -from [get_ports sys_rst_n]
Clock constraints example:
First, the input reference clock period is specified, which can be 100 MHz, 125 MHz, or
250 MHz (selected in the Vivado IDE).
create_clock -name sys_clk -period 10 [get_pins refclk_ibuf/O]
Next, the internally generated clock net and period are specified, which can be 100 MHz,
125 MHz, or 250 MHz.
Note: Both clock constraints must be specified as 100 MHz, 125 MHz, or 250 MHz.
create_generated_clock -name clk_125mhz -source [get_pins refclk_ibuf/O] -edges {1 2
3} -edge_shift {0 -1 -2} [get_pins ext_clk.pipe_clock_i/mmcm_i/CLKOUT0]
create_generated_clock -name clk_userclk -source [get_pins refclk_ibuf/O] -edges {1
2 3} -edge_shift {0 3 6} [get_pins ext_clk.pipe_clock_i/mmcm_i/CLKOUT2]
Relocating the Integrated Block Core
While Xilinx does not provide technical support for designs whose system clock input, GTXE
transceivers, or block RAM locations are different from the provided examples, it is possible
to relocate the core within the FPGA. The locations selected in the IP core and the examples
provided are the recommended pinouts. These locations have been chosen based on the
proximity to the PCIe® block, which enables meeting 250 MHz timing, and because they
are conducive to layout requirements for add-in card design. If the core is moved, the
relative location of all transceivers and clocking resources should be maintained to ensure
timing closure.
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Chapter 4: Design Flow Steps
By default, the IP core-level constraints lock block RAMs, transceivers, and the PCIe block to
the recommended location. To relocate these blocks, you must override the constraints for
these blocks in the XDC constraint file. To do so:
1. Copy the constraints for the block that needs to be overwritten from the core-level XDC
constraint file.
2. Place the constraints in the user XDC constraint file.
3. Update the constraints with the new location.
The user XDC constraints are usually scoped to the top-level of the design; therefore, you
must ensure that the cells referred by the constraints are still valid after copying and
pasting them. Typically, you need to update the module path with the full hierarchy name.
Note: If there are locations that need to be swapped (i.e., the new location is currently being
occupied by another module), there are two ways to do this.
•
If there is a temporary location available, move the first module out of the way to a
new temporary location first. Then, move the second module to the location that was
occupied by the first module. Then, move the first module to the location of the
second module. These steps can be done in XDC constraint file.
•
If there is no other location available to be used as a temporary location, use the
reset_property command from Tcl command window on the first module before
relocating the second module to this location. The reset_property command
cannot be done in XDC constraint file and must be called from the Tcl command file or
typed directly into the Tcl Console.
Available Integrated Blocks for PCIe
Virtex®-7 FPGAs contain multiple blocks. Table 4-6 lists which blocks are available for use
in these FPGAs. Kintex®-7 and Artix®-7 devices only contain one block. In some Virtex-7
family cases, not all blocks can be targeted due to the lack of bonded transceivers sites
adjacent to the Integrated Block. The Integrated Blocks in FPGAs listed in Table 4-6 only
support operations up to Gen2 (5.0 GT/s) speeds. For Gen 3 (8.0 GT/s) operation, see
Virtex-7 FPGA Gen3 Integrated Block for PCI Express Product Guide (PG023) [Ref 4].
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Chapter 4: Design Flow Steps
Table 4-6:
Available Integrated Blocks for PCIe
Device Selection
Device
aZynq-7000
Package
X0Y0
XC7Z015
CLG485
✔
XC7Z030
FBG484
FBG676
FFG676
SBG485
FBV484
FBV676
FFV676
✔
XC7Z035
FBG676
FFG676
FFG900
FBV676
FFV676
FFV900
✔
XC7Z045
FBG676
FFG676
FFG900
FBV676
FFV676
FFV900
✔
XC7Z100
FFG900
FFG1156
FFV676
FFV1156
✔
XQ7Z030
RB484
RF676
✔
XQ7Z045
RF676
RF900
RFG676
✔
XQ7Z100
RF1156
✔
XA7Z030
FBG484
✔
Zynq®-7000
qZynq-7000
Integrated Block for PCIe Location
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Chapter 4: Design Flow Steps
Table 4-6:
Available Integrated Blocks for PCIe (Cont’d)
Device Selection
Device
XC7VX485T
Virtex-7
XC7V585T
XC7V2000T
XQ7VX485T
qVirtex-7
XQ7VX585T
Integrated Block for PCIe Location
Package
X0Y0
X0Y1
X0Y2
X1Y0
X1Y1
FFG1157
✔
✔
FFG1761
✔
✔
FFG1930
✔
✔
FFG1158
✔
✔
✔
✔
FFG1927
✔
✔
✔
✔
RF1761
✔
✔
RF1930
✔
✔
FFG1157
✔
✔
FFG1761
✔
✔
✔
FHG1761
✔
✔
✔
FLG1925
✔
✔
RF1157
RF1761
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✔
✔
✔
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Chapter 4: Design Flow Steps
Table 4-6:
Available Integrated Blocks for PCIe (Cont’d)
Device Selection
Device
Integrated Block for PCIe Location
Package
X0Y0
XC7K480T
FFG901
FFG1156
FFV901
FFV1156
✔
XC7K420T
FFG901
FFG1156
FFV901
FFV1156
✔
XC7K410T
FBG676
FBG900
FFG676
FFG900
FBV676
FBV900
FFV676
FFV900
✔
XC7K355T
FFG901
FFV901
✔
XC7K325T
FBG676
FBG900
FFG676
FFG900
FBV676
FBV900
FFV676
FFV900
✔
XCK7160T
FBG484
FBG676
FFG676
FBV484
FBV676
FFV676
✔
XC7K70T
FBG484
FBG676
FBV484
FBV676
✔
XQ7K325T
RF676
RF900
✔
XQ7K410T
RF676
RF900
✔
Kintex-7
qKintex-7
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Chapter 4: Design Flow Steps
Table 4-6:
Available Integrated Blocks for PCIe (Cont’d)
Device Selection
Device
Integrated Block for PCIe Location
Package
X0Y0
XC7K480T
FFG901
FFG1156
FFV901
FFV1156
✔
XC7K420T
FFG901
FFG1156
FFV901
FFV1156
✔
XC7K410T
FBG676
FBG900
FFG676
FFG900
FBV676
FBV900
FFV676
FFV900
✔
XC7K355T
FFG901
FFV901
✔
XC7K325T
FBG676
FBG900
FFG676
FFG900
FBV676
FBV900
FFV676
FFV900
✔
XCK7160T
FBG484
FBG676
FFG676
FBV484
FBV676
FFV676
✔
XC7K70T
FBG484
FBG676
FBV484
FBV676
✔
XQ7K325T
RF676
RF900
✔
XQ7K410T
RF676
RF900
✔
Kintex-7l
qKintex-7l
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Chapter 4: Design Flow Steps
Table 4-6:
Available Integrated Blocks for PCIe (Cont’d)
Device Selection
Device
Artix-7
qArtix-7
aArtix-7
Integrated Block for PCIe Location
Package
X0Y0
XC7A15T
CPG236
CSG325
FGG484
✔
XC7A35T
CPG236
CSG325
FGG484
✔
XC7A50T
CPG236
CSG325
FGG484
✔
XC7A75T
FGG484
✔
XC7A100T
FGG484
FGG676
✔
XC7A200T
FBG484
FBG676
FFG1156
SBG484
FFV1156
FBV676
FBV484
✔
XQ7A100T
FG484
✔
XQ7A200T
RB484
RS484
RB676
✔
XQ7A50T
CS325
✔
XA7A15T
CSG325
✔
XA7A35T
CPG236
CSG325
FGG484
✔
XA7A50T
CPG236
CSG325
FGG484
✔
XA7A75T
FGG676
FGG484
✔
XA7A100T
FGG484
✔
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Chapter 4: Design Flow Steps
Table 4-6:
Available Integrated Blocks for PCIe (Cont’d)
Device Selection
Integrated Block for PCIe Location
Device
Artix-7l
Package
X0Y0
XC7A15T
CPG236
CSG325
FGG484
✔
XC7A35T
CPG236
CSG325
FGG484
✔
XC7A50T
CPG236
CSG325
FGG484
✔
XC7A75T
FGG484
✔
XC7A100T
FGG484
FGG676
✔
XC7A200T
FBG484
FBG676
FFG1156
SBG484
FFV1156
FBV676
FBV484
✔
X0Y1
X0Y2
X1Y0
X1Y1
Recommended Core Pinouts
Zynq-7000 Devices
Table 4-7 defines the recommended core pinouts for the available Zynq-7000 device part
and package combinations. The Vivado Design Suite provides an XDC for the selected part
and package that matches the table contents.
Note: You can select other core pinouts than those listed in the table if the timing is met in the
design. To select other core pinouts, manually modify the generated constraints in the XDC file.
Table 4-7:
Device
Zynq-7000 Recommended Core Pinouts
Package
Integrated
Block
Location
Lane
Lane 0
XC7Z015
CLG485
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X0Y0
Lane 1
X1
X0Y3
X2
X4
X0Y3
X0Y3
X0Y2
X0Y2
Lane 2
X0Y1
Lane 3
X0Y0
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Chapter 4: Design Flow Steps
Table 4-7:
Zynq-7000 Recommended Core Pinouts (Cont’d)
Device
Package
XC7Z030
FBG484, FBG676,
FFG676, SBG485,
FBV484, FBV676,
FFV676
XC7Z035
XC7Z045
XC7Z100
Integrated
Block
Location
Lane 0
X0Y0
FFG900, FFG1156,
FFV900, FFV1156
X0Y3
X2
X4
X0Y3
X0Y3
X0Y2
X0Y2
Lane 2
X0Y1
Lane 3
X0Y0
X0Y15
X8
Not
Supported
X0Y15
X0Y15
X0Y15
X0Y14
X0Y14
X0Y14
Lane 2
X0Y13
X0Y13
Lane 3
X0Y12
X0Y12
Lane 1
X0Y0
X1
Lane 1
Lane 0
FBG676, FFG676,
FFG900, FBV676,
FFV676, FFV900
FBG676, FFG676,
FFG900, FBV676,
FFV676, FFV900
Lane
Lane 4
X0Y11
Lane 5
X0Y10
Lane 6
X0Y9
Lane 7
X0Y8
Virtex-7 Devices
Table 4-8, Table 4-9, and Table 4-10 define the recommended core pinouts for the available
Virtex-7 device part and package combinations. The Vivado Design Suite provides an XDC
for the selected part and package that matches the table contents.
Note: You can select other core pinouts than those listed in the table if the timing is met in the
design. To select other core pinouts, manually modify the generated constraints in the XDC file.
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Chapter 4: Design Flow Steps
Table 4-8:
Virtex-7 XC7VX485T Recommended Core Pinouts
Package
Integrated
Block Location
Lane
X1
X2
X4
X0Y11
X0Y11
X0Y11
X0Y11
X0Y10
X0Y10
X0Y10
Lane 2
X0Y9
X0Y9
Lane 3
X0Y8
X0Y8
Lane 0
Lane 1
X0Y0
FFG1158, FFG1927
Lane 4
X0Y7
Lane 5
X0Y6
Lane 6
X0Y5
Lane 7
X0Y4
Lane 0
X0Y23
X0Y23
X0Y23
X0Y23
X0Y22
X0Y22
X0Y22
Lane 2
X0Y21
X0Y21
Lane 3
X0Y20
X0Y20
Lane 1
X0Y1
Lane 4
X0Y19
Lane 5
X0Y18
Lane 6
X0Y17
Lane 7
X0Y16
Lane 0
X1Y11
X1Y11
X1Y11
X1Y11
X1Y10
X1Y10
X1Y10
Lane 2
X1Y9
X1Y9
Lane 3
X1Y8
X1Y8
Lane 1
X1Y0
FFG1157, FFG1761,
FFG1930
Lane 4
X1Y7
Lane 5
X1Y6
Lane 6
X1Y5
Lane 7
X1Y4
Lane 0
X1Y23
X1Y23
X1Y23
X1Y23
X1Y22
X1Y22
X1Y22
Lane 2
X1Y21
X1Y21
Lane 3
X1Y20
X1Y20
Lane 1
X1Y1
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Lane 4
X1Y19
Lane 5
X1Y18
Lane 6
X1Y17
Lane 7
X1Y16
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Chapter 4: Design Flow Steps
Table 4-9:
Virtex-7 XC7V585T Recommended Core Pinouts
Package
Integrated
Block Location
Lane
X1
X2
X4
X0Y19
X0Y19
X0Y19
X0Y19
X0Y18
X0Y18
X0Y18
Lane 2
X0Y17
X0Y17
Lane 3
X0Y16
X0Y16
Lane 0
Lane 1
X0Y1
FFG1157
Lane 4
X0Y15
Lane 5
X0Y14
Lane 6
X0Y13
Lane 7
X0Y12
Lane 0
X0Y31
X0Y31
X0Y31
X0Y31
X0Y30
X0Y30
X0Y30
Lane 2
X0Y29
X0Y29
Lane 3
X0Y28
X0Y28
Lane 1
X0Y2
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Lane 4
X0Y27
Lane 5
X0Y26
Lane 6
X0Y25
Lane 7
X0Y24
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Chapter 4: Design Flow Steps
Table 4-9:
Virtex-7 XC7V585T Recommended Core Pinouts (Cont’d)
Package
Integrated
Block Location
Lane
Lane 0
X1
X0Y7
X0Y7
X0Y6
X0Y6
X0Y6
Lane 2
X0Y5
X0Y5
Lane 3
X0Y4
X0Y4
Lane 4
X0Y3
Lane 5
X0Y2
Lane 6
X0Y1
Lane 7
X0Y0
X0Y19
X0Y19
X0Y19
X0Y19
X0Y18
X0Y18
X0Y18
Lane 2
X0Y17
X0Y17
Lane 3
X0Y16
X0Y16
Lane 1
X0Y1
Lane 4
X0Y15
Lane 5
X0Y14
Lane 6
X0Y13
Lane 7
X0Y12
Lane 0
X0Y31
X0Y31
X0Y31
X0Y31
X0Y30
X0Y30
X0Y30
Lane 2
X0Y29
X0Y29
Lane 3
X0Y28
X0Y28
Lane 1
X0Y2
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X0Y7
Lane 0
FFG1761
X4
X0Y7
Lane 1
X0Y0
X2
Lane 4
X0Y27
Lane 5
X0Y26
Lane 6
X0Y25
Lane 7
X0Y24
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Chapter 4: Design Flow Steps
Table 4-10:
Virtex-7 XC7V2000T Recommended Core Pinouts
Package
Integrated
Block Location
Lane
Lane 0
X1
X0Y7
X0Y7
X0Y6
X0Y6
X0Y6
Lane 2
X0Y5
X0Y5
Lane 3
X0Y4
X0Y4
Lane 4
X0Y3
Lane 5
X0Y2
Lane 6
X0Y1
Lane 7
X0Y0
X0Y19
X0Y19
X0Y19
X0Y19
X0Y18
X0Y18
X0Y18
Lane 2
X0Y17
X0Y17
Lane 3
X0Y16
X0Y16
Lane 1
X0Y1
Lane 4
X0Y15
Lane 5
X0Y14
Lane 6
X0Y13
Lane 7
X0Y12
Lane 0
X0Y31
X0Y31
X0Y31
X0Y31
X0Y30
X0Y30
X0Y30
Lane 2
X0Y29
X0Y29
Lane 3
X0Y28
X0Y28
Lane 1
X0Y2
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X0Y7
Lane 0
FHG1761
X4
X0Y7
Lane 1
X0Y0
X2
Lane 4
X0Y27
Lane 5
X0Y26
Lane 6
X0Y25
Lane 7
X0Y24
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Chapter 4: Design Flow Steps
Table 4-10:
Virtex-7 XC7V2000T Recommended Core Pinouts (Cont’d)
Package
Integrated
Block Location
Lane
X1
X2
X4
X0Y11
X0Y11
X0Y11
X0Y11
X0Y10
X0Y10
X0Y10
Lane 2
X0Y9
X0Y9
Lane 3
X0Y8
X0Y8
Lane 0
Lane 1
X0Y0
FLG1925
Lane 4
X0Y7
Lane 5
X0Y6
Lane 6
X0Y5
Lane 7
X0Y4
Lane 0
X0Y19
X0Y19
X0Y19
X0Y19
X0Y18
X0Y18
X0Y18
Lane 2
X0Y17
X0Y17
Lane 3
X0Y16
X0Y16
Lane 1
X0Y1
X8
Lane 4
X0Y15
Lane 5
X0Y14
Lane 6
X0Y13
Lane 7
X0Y12
Kintex-7 Devices
Table 4-11 defines the recommended core pinouts for the available Kintex-7 device part
and package combinations. The Vivado Design Suite provides an XDC for the selected part
and package that matches the table contents.
Note: You can select other core pinouts than those listed in the table if the timing is met in the
design. To select other core pinouts, manually modify the generated constraints in the XDC file.
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Chapter 4: Design Flow Steps
Table 4-11:
Device
Kintex-7 Recommended Core Pinouts
Package
Integrated
Block
Location
Lane
Lane 0
FBG484, FBV484
X0Y0
X0Y3
Lane 1
FBG676, FBV676
X0Y0
X0Y0
X0Y7
X0Y0
7 Series Integrated Block for PCIe v3.1
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Not
Supported
X0Y7
X0Y6
X0Y6
X0Y6
Lane 2
X0Y5
X0Y5
Lane 3
X0Y4
X0Y4
Lane 4
X0Y3
Lane 5
X0Y2
Lane 6
X0Y1
Lane 7
X0Y0
X0Y3
Lane 1
X0Y3
X0Y3
X0Y2
X0Y2
Lane 2
X0Y1
Lane 3
X0Y0
X0Y7
Not
Supported
X0Y7
X0Y7
X0Y7
X0Y6
X0Y6
X0Y6
Lane 2
X0Y5
X0Y5
Lane 3
X0Y4
X0Y4
Lane 4
X0Y3
Lane 5
X0Y2
Lane 6
X0Y1
Lane 7
X0Y0
X0Y7
X0Y7
X0Y7
X0Y6
X0Y6
X0Y6
Lane 2
X0Y5
X0Y5
Lane 3
X0Y4
X0Y4
Lane 1
X0Y0
X0Y2
X0Y7
Lane 0
FBG676, FBG900,
FFG676, FFG900,
FBV676, FBV900,
FFV676, FFV900
X0Y2
X8
X0Y7
Lane 1
FBG676, FFG676,
FBV676, FFV676
X0Y3
X0Y0
Lane 0
XC7K160T
X0Y3
Lane 3
Lane 0
FBG484, FBV484
X4
X0Y1
Lane 1
XC7K70T
X2
Lane 2
Lane 0
XC7K325T
X1
X0Y7
Lane 4
X0Y3
Lane 5
X0Y2
Lane 6
X0Y1
Lane 7
X0Y0
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Table 4-11:
Device
Kintex-7 Recommended Core Pinouts (Cont’d)
Package
Integrated
Block
Location
Lane
X1
X2
X4
Lane 0
X0Y15
X0Y15
X0Y15
X0Y15
X0Y14
X0Y14
X0Y14
Lane 2
X0Y13
X0Y13
Lane 3
X0Y12
X0Y12
Lane 1
XC7K355T
FFG901, FFV901
X0Y0
Lane 4
X0Y11
Lane 5
X0Y10
Lane 6
X0Y9
Lane 7
X0Y8
Lane 0
X0Y7
X0Y7
X0Y7
X0Y7
X0Y6
X0Y6
X0Y6
Lane 2
X0Y5
X0Y5
Lane 3
X0Y4
X0Y4
Lane 1
XC7K410T
FBG676, FBG900,
FFG676, FFG900,
FBV676, FBV900,
FFV676, FFV900
X0Y0
Lane 4
X0Y3
Lane 5
X0Y2
Lane 6
X0Y1
Lane 7
X0Y0
Lane 0
X0Y19
X0Y19
X0Y19
X0Y18
X0Y18
X0Y18
Lane 2
X0Y17
X0Y17
Lane 3
X0Y16
X0Y16
Lane 1
XC7K420T
XC7K480T
FFG901, FFG1156,
FFV901, FFV1156
X0Y0
X8
X0Y19
Lane 4
X0Y15
Lane 5
X0Y14
Lane 6
X0Y13
Lane 7
X0Y12
Artix-7 Devices
Table 4-12 defines the recommended core pinouts for the available Artix-7 device part and
package combinations. The Vivado Design Suite provides an XDC for the selected part and
package that matches the table contents.
Note: You can select other core pinouts than those listed in the table if the timing is met in the
design. To select other core pinouts, manually modify the generated constraints in the XDC file.
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Table 4-12:
Device
XC7A200T
Artix-7 Recommended Core Pinouts
Package
FBG484, FBG676, FFG1156,
SBG484, FBV484, FBV676,
FFV1156
XC7A100T
FGG484, FGG676
XC7A75T
FGG484, FGG676
Integrated
Block
Location
X0Y0
Lane
X1
X2
X4
Lane 0
X0Y7
X0Y7
X0Y7
X0Y6
X0Y6
Lane 1
Lane 2
X0Y5
Lane 3
X0Y4
Lane 0
XC7A35T
XC7A50T
FGG484, CPG236, CSG325
X0Y0
FGG484, CPG236, CSG325
Lane 1
CPG236, CSG325, FGG484
X0Y0
X0Y3
X0Y3
X0Y2
X0Y2
Lane 2
X0Y1
Lane 3
X0Y0
Lane 0
XC7A15T
X0Y3
X0Y3
Lane 1
X0Y3
X0Y3
X0Y2
X0Y2
Lane 2
X0Y1
Lane 3
X0Y0
X8
Not
Supported
Not
Supported
Not
Supported
Simulation
This section contains information about simulating IP in the Vivado Design Suite.
•
For comprehensive information about Vivado simulation components, as well as
information about using supported third party tools, see the Vivado Design Suite User
Guide: Logic Simulation (UG900) [Ref 16].
•
For information about simulating the example design, see Simulating the Example
Design in Chapter 5.
IMPORTANT: For cores targeting 7 series or Zynq-7000 devices, UNIFAST libraries are not supported.
Xilinx IP is tested and qualified with UNISIM libraries only.
Simulating with Tandem Configurations
For specific requirements for simulating with Tandem Configurations, see Simulating the
Tandem IP Core in Chapter 3.
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PIPE Mode Simulations
This section describes PIPE Mode simulations with the example design. For third-party bus
functional model support, see the PIPE Mode Simulation Using Integrated Endpoint PCI
Express Block in Gen2 x8 Configurations Application Note (XAPP1184) [Ref 21].
The PIPE Simulation mode allows you to run the simulations without serial transceiver block
to speed up simulations.
To run the simulations using the PIPE interface to speed up the simulation, generate the
core after selecting the Enable PIPE Simulation radio button under the PIPE Mode
Simulations group box on in the Basic tab of the Customize IP dialog box. For details, see
PIPE Mode Simulations, page 208. In this mode the PIPE interface of the core top module,
the PCIe® example design is connected to PIPE interface of the model. This feature is
available only for a Verilog version of the core.
IMPORTANT: A new <component_name>_gt_top_pipe.v file is created in the source directory
and replaces serial transceiver block for PIPE mode simulation.
Third-party simulation support pulls out the following ports when Enable External PIPE
interface ports is selected.
For PIPE ports to and from the pcie_top, each lane has independent input and output bus
signals, as shown in Table 4-13.
Table 4-13:
PIPE_PORTS Bus Signals
Direction (Input/Output)
to/from pcie_top
Size
Input
[3:0]
common_commands_in
Input
[24:0]
pipe_rx_0_sigs
Input
[24:0]
pipe_rx_1_sigs
Input
[24:0]
pipe_rx_2_sigs
Input
[24:0]
pipe_rx_3_sigs
Input
[24:0]
pipe_rx_4_sigs
Input
[24:0]
pipe_rx_5_sigs
Input
[24:0]
pipe_rx_6_sigs
Input
[24:0]
pipe_rx_7_sigs
Output
[11:0]
common_commands_out
Output
[22:0]
pipe_tx_0_sigs
Output
[22:0]
pipe_tx_1_sigs
Output
[22:0]
pipe_tx_2_sigs
Output
[22:0]
pipe_tx_3_sigs
Output
[22:0]
pipe_tx_4_sigs
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Table 4-13:
PIPE_PORTS Bus Signals
Direction (Input/Output)
to/from pcie_top
Size
Output
[22:0]
pipe_tx_5_sigs
Output
[22:0]
pipe_tx_6_sigs
Output
[22:0]
pipe_tx_7_sigs
I/O Bus Signals
Table 4-14, Table 4-15, and Table 4-16 provide PIPE ports and their mapping to input and
output bus signals.
Table 4-14:
Control and Status Port Mappings
Input and Output Bus Signal
Port
common_commands_in[0]
pipe_clk
common_commands_in[1]
user_clk
common_commands_in[2]
user_clk2
common_commands_in[3]
phy_rdy_n
common_commands_out[5:0]
pl_ltssm_state
common_commands_out[6]
pipe_tx_rcvr_det_gt
common_commands_out[7]
pipe_tx_rate_gt
common_commands_out[8]
pipe_tx_deemph_gt
common_commands_out[11:9]
pipe_tx_margin_gt
Table 4-15:
TX Signal Mappings
Input and Outpus Bus Signal
Port
pipe_tx_0_sigs[15:0]
pipe_tx0_data_gt
pipe_tx_0_sigs[17:16]
pipe_tx0_char_is_k_gt
pipe_tx_0_sigs[18]
pipe_tx0_polarity_gt
pipe_tx_0_sigs[19]
pipe_tx0_compliance_gt
pipe_tx_0_sigs[20]
pipe_tx0_elec_idle_gt
pipe_tx_0_sigs[22:21]
pipe_tx0_powerdown_gt
Note: Lanes 1 to 7 use similar signal definitions.
Table 4-16:
RX Signal Mappings
Input and Outpus Bus Signal
Port
pipe_rx_0_sigs[15:0]
pipe_rx0_data_gt
pipe_rx_0_sigs[17:16]
pipe_rx0_char_is_k_gt
pipe_rx_0_sigs[18]
pipe_rx0_valid_gt
pipe_rx_0_sigs[19]
pipe_rx0_chanisaligned_gt
pipe_rx_0_sigs[22:20]
pipe_rx0_status_gt
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Table 4-16:
RX Signal Mappings
Input and Outpus Bus Signal
Port
pipe_rx_0_sigs[23]
pipe_rx0_phy_status_gt
pipe_rx_0_sigs[24]
pipe_rx0_elec_idle_gt
Note: Lanes 1 to 7 use similar signal definitions.
Synthesis and Implementation
•
For further details about synthesis and implementation, see the Vivado Design Suite
User Guide: Designing with IP (UG896) [Ref 15].
•
For information regarding synthesizing and implementing the example design, see
Synthesizing and Implementing the Example Design in Chapter 5.
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Chapter 5
Detailed Example Designs
This section provides an overview of the 7 Series FPGAs Integrated Block for PCI Express®
example designs, and instructions for generating the core.
Integrated Block Endpoint Configuration Overview
The example simulation design for the Endpoint configuration of the integrated block
consists of two discrete parts:
•
The Root Port Model: A test bench that generates, consumes, and checks PCI Express
bus traffic.
•
The Programmed Input/Output (PIO) example design: A completer application for
PCI Express. The PIO example design responds to Read and Write requests to its
memory space and can be synthesized for testing in hardware.
Simulation Design Overview
For the simulation design, transactions are sent from the Root Port Model to the core
(configured as an Endpoint) and processed by the PIO example design. Figure 5-1
illustrates the simulation design provided with the Integrated Block core. For more
information about the Root Port Model, see Root Port Model Test Bench for Endpoint in
Chapter 6.
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Chapter 5: Detailed Example Designs
X-Ref Target - Figure 5-1
Output
Logs
Root Port
Model TPI for
PCI Express
usrapp_com
usrapp_rx
Test
Program
usrapp_tx
dsport
PCI Express Fabric
Endpoint Core
for PCI Express
PIO
Design
Endpoint DUT for PCI Express
Figure 5-1:
Simulation Example Design Block Diagram
Implementation Design Overview
The implementation design consists of a simple PIO example that can accept read and write
transactions and respond to requests, as illustrated in Figure 5-2. Source code for the
example is provided with the core. For more information about the PIO example design, see
Chapter 6, Test Benches.
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X-Ref Target - Figure 5-2
7 Series FPGAs Integrated Block for PCI Express (Configured as Endpoint)
ep_mem0
PIO_TO_CTRL
ep_mem1
EP_TX
EP_RX
ep_mem2
ep_mem3
EP_MEM
PIO_EP
PIO
Figure 5-2:
Implementation Example Design Block Diagram
Example Design Elements
The PIO example design elements include:
•
Core wrapper
•
An example Verilog HDL or VHDL wrapper (instantiates the cores and example design)
•
A customizable demonstration test bench to simulate the example design
The example design has been tested and verified with Vivado® Design Suite with these
simulators:
•
Vivado simulator
•
Mentor Graphics QuestaSim
Note: ModelSim PE 10.2a is not supported.
•
Cadence Incisive Enterprise Simulator (IES)
•
Synopsys Verilog Compiler Simulator (VCS)
For the supported versions of these tools, see the Xilinx Design Tools: Release Notes
Guide (3).
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Chapter 5: Detailed Example Designs
Programmed Input/Output: Endpoint Example
Design
Programmed Input/Output (PIO) transactions are generally used by a PCI Express® system
host CPU to access Memory Mapped Input/Output (MMIO) and Configuration Mapped
Input/Output (CMIO) locations in the PCI Express logic. Endpoints for PCI Express accept
Memory and I/O Write transactions and respond to Memory and I/O Read transactions with
Completion with Data transactions.
The PIO example design (PIO design) is included with the core in an Endpoint configuration
generated by the Vivado Integrated Design Environment (IDE).
TIP: You can bring up the system board and verify the link and functionality of the board using the PIO
design, which is an established working design.
Note: The PIO design Port Model is shared by the 7 Series FPGAs Integrated Block for PCI Express,
Endpoint Block Plus for PCI Express, and Endpoint PIPE for PCI Express solutions. This chapter
represents all the solutions generically using the name Endpoint for PCI Express (or Endpoint for
PCIe®).
System Overview
The PIO design is a simple target-only application that interfaces with the Endpoint for PCIe
core Transaction (AXI4-Stream) interface and is provided as a starting point for building
your own designs. These features are included:
•
Four transaction-specific 2 KB target regions using the internal Xilinx FPGA block
RAMs, providing a total target space of 8192 bytes
•
Supports single DWORD payload Read and Write PCI Express transactions to 32-/64-bit
address memory spaces and I/O space with support for completion transaction layer
packets (TLPs)
•
Utilizes the (rx_bar_hit[7:0]) m_axis_rx_tuser[9:2] signals of the core to differentiate
between TLP destination Base Address Registers
•
Provides separate implementations optimized for 32-bit, 64-bit, and 128-bit
AXI4-Stream interfaces
Figure 5-3 illustrates the PCI Express system architecture components, consisting of a Root
Complex, a PCI Express switch device, and an Endpoint for PCIe. PIO operations move data
downstream from the Root Complex (CPU register) to the Endpoint, and/or upstream from
the Endpoint to the Root Complex (CPU register). In either case, the PCI Express protocol
request to move the data is initiated by the host CPU.
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X-Ref Target - Figure 5-3
PCIe
Root Complex
CPU
Main
Memory
Memory
Controller
Device
PCI_BUS_0
PCIe
Port
PCI_BUS_1
PCIe
Switch
PCI_BUS_X
PCIe
Endpoint
Figure 5-3:
PCI Express System Overview
Data is moved downstream when the CPU issues a store register to a MMIO address
command. The Root Complex typically generates a Memory Write TLP with the appropriate
MMIO location address, byte enables, and the register contents. The transaction terminates
when the Endpoint receives the Memory Write TLP and updates the corresponding local
register.
Data is moved upstream when the CPU issues a load register from a MMIO address
command. The Root Complex typically generates a Memory Read TLP with the appropriate
MMIO location address and byte enables. The Endpoint generates a Completion with Data
TLP after it receives the Memory Read TLP. The Completion is steered to the Root Complex
and payload is loaded into the target register, completing the transaction.
PIO Hardware
The PIO design implements a 8192 byte target space in FPGA block RAM, behind the
Endpoint for PCIe. This 32-bit target space is accessible through single DWORD I/O Read,
I/O Write, Memory Read 64, Memory Write 64, Memory Read 32, and Memory Write 32
TLPs.
The PIO design generates a completion with one DWORD of payload in response to a valid
Memory Read 32 TLP, Memory Read 64 TLP, or I/O Read TLP request presented to it by the
core. In addition, the PIO design returns a completion without data with successful status
for I/O Write TLP request.
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The PIO design processes a Memory or I/O Write TLP with one DWORD payload by
updating the payload into the target address in the FPGA block RAM space.
Base Address Register Support
The PIO design supports four discrete target spaces, each consisting of a 2 KB block of
memory represented by a separate Base Address Register (BAR). Using the default
parameters, the Vivado IDE produces a core configured to work with the PIO design that
consists of:
•
One 64-bit addressable Memory Space BAR
•
One 32-bit Addressable Memory Space BAR
You can change the default parameters used by the PIO design; however, in some cases you
might need to change the user application depending on your system. See Changing the
Default BAR Settings for information about changing the default parameters and the effect
on the PIO design.
Each of the four 2 KB address spaces represented by the BARs corresponds to one of four
2 KB address regions in the PIO design. Each 2 KB region is implemented using a 2 KB
dual-port block RAM. As transactions are received by the core, the core decodes the
address and determines which of the four regions is being targeted. The core presents the
TLP to the PIO design and asserts the appropriate bits of (rx_bar_hit[7:0])
m_axis_rx_tuser[9:2], as defined in Table 5-1.
Table 5-1:
TLP Traffic Types
Block RAM
TLP Transaction Type
Default BAR
rx_bar_hit[7:0]
Disabled
Disabled
ep_mem0
I/O TLP transactions
ep_mem1
32-bit address Memory TLP transactions
0
0000_0001b
ep_mem2
64-bit address Memory TLP transactions
Disabled
Disabled
ep_mem3
32-bit address Memory TLP transactions
destined for EROM
Expansion ROM
0100_0000b
Changing the Default BAR Settings
You can change the parameters and continue to use the PIO design to create customized
Verilog or VHDL source to match the selected BAR settings. However, because the PIO
design parameters are more limited than the core parameters, consider these example
design limitations when changing the default parameters:
•
The example design supports one I/O space BAR, one 32-bit Memory space (that
cannot be the Expansion ROM space), and one 64-bit Memory space. If these limits are
exceeded, only the first space of a given type is active—accesses to the other spaces do
not result in completions.
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Chapter 5: Detailed Example Designs
•
Each space is implemented with a 2 KB memory. If the corresponding BAR is configured
to a wider aperture, accesses beyond the 2 KB limit wrap around and overlap the 2 KB
memory space.
•
The PIO design supports one I/O space BAR, which by default is disabled, but can be
changed if desired.
TIP: Although there are limitations to the PIO design, Verilog or VHDL source code is provided so you
can tailor the example design to your specific needs.
TLP Data Flow
This section defines the data flow of a TLP successfully processed by the PIO design. For
detailed information about the interface signals within the sub-blocks of the PIO design,
see Receive Path, page 273 and Transmit Path, page 274.
The PIO design successfully processes single DWORD payload Memory Read and Write TLPs
and I/O Read and Write TLPs. Memory Read or Memory Write TLPs of lengths larger than
one DWORD are not processed correctly by the PIO design; however, the core does accept
these TLPs and passes them along to the PIO design. If the PIO design receives a TLP with
a length of greater than one DWORD, the TLP is received completely from the core and
discarded. No corresponding completion is generated.
Memory and I/O Write TLP Processing
When the Endpoint for PCIe receives a Memory or I/O Write TLP, the TLP destination
address and transaction type are compared with the values in the core BARs. If the TLP
passes this comparison check, the core passes the TLP to the Receive AXI4-Stream interface
of the PIO design. The PIO design handles Memory writes and I/O TLP writes in different
ways: the PIO design responds to I/O writes by generating a Completion Without Data (cpl),
a requirement of the PCI Express specification.
Along with the start of packet, end of packet, and ready handshaking signals, the Receive
AXI4-Stream interface also asserts the appropriate (rx_bar_hit[7:0]) m_axis_rx_tuser[9:2]
signal to indicate to the PIO design the specific destination BAR that matched the incoming
TLP. On reception, the RX State Machine of the PIO design processes the incoming Write TLP
and extracts the TLPs data and relevant address fields so that it can pass this along to the
internal block RAM write request controller of the PIO design.
Based on the specific rx_bar_hit[7:0] signal asserted, the RX State Machine indicates to the
internal write controller the appropriate 2 KB block RAM to use prior to asserting the write
enable request. For example, if an Memory Write 32 Request is received by the core
targeting BAR0, the core passes the TLP to the PIO design and asserts rx_bar_hit[0]. The RX
State machine extracts the lower address bits and the data field from the Memory Write 32
Request TLP and instructs the internal Memory Write controller to begin a write to the block
RAM.
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In this example, the assertion of rx_bar_hit[0] instructed the PIO memory write controller to
access ep_mem1 (which by default represents 2 KB of Mem32 space). While the write is
being carried out to the FPGA block RAM, the PIO design RX state machine deasserts the
m_axis_rx_tready, causing the Receive AXI4-Stream interface to stall receiving any further
TLPs until the internal Memory Write controller completes the write to the block RAM.
Deasserting m_axis_rx_tready in this way is not required for all designs using the core—the
PIO design uses this method to simplify the control logic of the RX state machine.
Memory and I/O Read TLP Processing
When the Endpoint for PCIe receives a Memory or I/O Read TLP, the TLP destination address
and transaction type are compared with the values programmed in the core BARs. If the TLP
passes this comparison check, the core passes the TLP to the Receive AXI4-Stream interface
of the PIO design.
Along with the start of packet, end of packet, and ready handshaking signals, the Receive
AXI4-Stream interface also asserts the appropriate rx_bar_hit[7:0] signal to indicate to the
PIO design the specific destination BAR that matched the incoming TLP. On reception, the
state machine of the PIO design processes the incoming Read TLP and extracts the relevant
TLP information and passes it along to the internal block RAM read request controller of the
PIO design.
Based on the specific rx_bar_hit[7:0] signal asserted, the RX state machine indicates to the
internal read request controller the appropriate 2 KB block RAM to use before asserting the
read enable request. For example, if a Memory Read 32 Request TLP is received by the core
targeting the default MEM32 BAR2, the core passes the TLP to the PIO design and asserts
rx_bar_hit[0]. The RX State machine extracts the lower address bits from the Memory 32
Read TLP and instructs the internal Memory Read Request controller to start a read
operation.
In this example, the assertion of rx_bar_hit[0] instructs the PIO memory read controller to
access the Mem32 space, which by default represents 2 KB of memory space. A notable
difference in handling of memory write and read TLPs is the requirement of the receiving
device to return a Completion with Data TLP in the case of memory or I/O read request.
While the read is being processed, the PIO design RX state machine deasserts
m_axis_rx_tready, causing the Receive AXI4-Stream interface to stall receiving any further
TLPs until the internal Memory Read controller completes the read access from the block
RAM and generates the completion. Deasserting m_axis_rx_tready in this way is not
required for all designs using the core. The PIO design uses this method to simplify the
control logic of the RX state machine.
PIO File Structure
Table 5-2 defines the PIO design file structure. Based on the specific core targeted, not all
files delivered by the Vivado IDE are necessary, and some files might not be delivered. The
major difference is that some of the Endpoint for PCIe solutions use a 64-bit user datapath,
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while others use a 128-bit datapath, and the PIO design works with both. The width of the
datapath depends on the specific core being targeted.
Table 5-2:
PIO Design File Structure
File
Description
pcie_app_7vx.v
Top-level design wrapper
PIO.v
PIO design wrapper
PIO_EP.v
PIO application module
PIO_TO_CTRL.v
PIO turn-off controller module
PIO_RX_ENGINE.v
64-bit/128-bit Receive engine
PIO_TX_ENGINE.v
64-bit/128-bit Transmit engine
PIO_EP_MEM_ACCESS.v
Endpoint memory access module
PIO_EP_MEM.v
Endpoint memory
Three configurations of the PIO design are provided: PIO_64, and PIO_128 with 64-, and
128-bit AXI4-Stream interfaces, respectively. The PIO configuration generated depends on
the selected Endpoint type (that is, 7 series FPGAs Integrated Block) as well as the number
of PCI Express lanes and the interface width you selected. Table 5-3 identifies the PIO
configuration generated based on your selection.
Table 5-3:
PIO Configuration
Core
7 Series FPGAs Integrated Block
x1
x2
x4
x8
PIO_64
PIO_64
PIO_64,
PIO_128
PIO_64,
PIO_128
Figure 5-4 shows the various components of the PIO design, which is separated into four
main parts: the TX Engine, RX Engine, Memory Access Controller, and Power Management
Turn-Off Controller.
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X-Ref Target - Figure 5-4
7 Series FPGAs Integrated Block for PCI Express Core (Configured as an Endpoint)
PIO_TO_CTRL
ep_mem0
ep_mem1
EP_TX
EP_RX
ep_mem2
ep_mem3
EP_MEM
PIO_EP
PIO
Figure 5-4:
PIO Design Components
PIO Application
Figure 5-5, and Figure 5-6 depict 128-bit, and 64-bit PIO application top-level connectivity,
respectively. The datapath width (32, 64, or 128 bits) depends on which Endpoint for PCIe
core is used. The PIO_EP module contains the PIO FPGA block RAM modules and the
transmit and receive engines. The PIO_TO_CTRL module is the Endpoint Turn-Off controller
unit, which responds to power turn-off message from the host CPU with an
acknowledgment.
The PIO_EP module connects to the Endpoint AXI4-Stream and Configuration (cfg)
interfaces.
X-Ref Target - Figure 5-5
S?AXIS?TX?TREADY
USER?CLK
M?AXIS?RX?TUSER;=
RX?IS?SOF;=
S?AXIS?TX?TUSER;=
S?AXIS?TX?TVALID
S?AXIS?TX?TLAST
0)/?%0
CLK
RST?N
USER?RESET
USER?LNK?UP
S?AXIS?TX?TREADY
PIO?RESET?N
M?AXIS?RX?TUSER;=
RX?IS?EOF;=
M?AXIS?RX?TVALID
CFG?BUS?MSTR?ENABLE
M?AXIS?RX?TUSER;=
RX?IS?EOF;=
M?AXIS?RX?TVALID
CFG?BUS?MSTR?ENABLE
;=
M?AXIS?RX?TDATA;=
M?AXIS?RX?TSTRB;=
CFG?COMPLETER?ID;=
S?AXIS?TX?TLAST
S?AXIS?TX?TUSER;=
S?AXIS?TX?TVALID
M?AXIS?RX?TREADY
REQ?COMPL?O
COMPL?DONE?O
M?AXIS?RX?TUSER;=
RX?IS?SOF;=
;=
;=
;=
;=
;=
M?AXIS?RX?TDATA;= S?AXIS?TX?TDATA;=
M?AXIS?RX?TSTRB;=
S?AXIS?TX?TSTRB;=
0)/?4/?#42,
CLK
RST?N
REQ?COMPL?I
COMPL?DONE?I
CFG?TO?TURNOFF
CFG?TURNOFF?OK
CFG?TURNOFF?OK
;=
;=
CFG?COMPLETER?ID;=
0)/?4/
;=
;=
0)/?%0
S?AXIS?TX?TSTRB;=
S?AXIS?TX?TDATA;=
M?AXIS?RX?TREADY
CFG?TO?TURNOFF
Figure 5-5:
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X-Ref Target - Figure 5-6
S?AXIS?TX?TREADY
USER?CLK
S?AXIS?TX?TUSER;=
S?AXIS?TX?TVALID
S?AXIS?TX?TLAST
0)/?%0
CLK
RST?N
USER?RESET
USER?LNK?UP
PIO?RESET?N
M?AXIS?RX?TLAST
M?AXIS?RX?TVALID
CFG?BUS?MSTR?ENABLE
CFG?BUS?MSTR?ENABLE
;=
M?AXIS?RX?TDATA;=
M?AXIS?RX?TSTRB;;=
CFG?COMPLETER?ID;=
S?AXIS?TX?TLAST
S?AXIS?TX?TUSER;=
S?AXIS?TX?TVALID
M?AXIS?RX?TREADY
REQ?COMPL?O
COMPL?DONE?O
S?AXIS?TX?TREADY
M?AXIS?RX?TLAST
M?AXIS?RX?TVALID
;=
;=
;=
;=
;=
M?AXIS?RX?TDATA;=
0)/?4/?#42,
CLK
RST?N
REQ?COMPL?I
COMPL?DONE?I
CFG?TO?TURNOFF
S?AXIS?TX?TDATA;=
;=
S?AXIS?TX?TSTRB;=
M?AXIS?RX?TSTRB;;=
CFG?TURNOFF?OK
CFG?TURNOFF?OK
0)/?4/
;=
CFG?COMPLETER?ID;=
;=
;=
0)/?%0
S?AXIS?TX?TSTRB;=
S?AXIS?TX?TDATA;=
M?AXIS?RX?TREADY
CFG?TO?TURNOFF
Figure 5-6:
PIO 64-Bit Application
Receive Path
Figure 5-7 illustrates the PIO_RX_ENGINE module. The datapath of the module must match
the datapath of the core being used. These modules connect with Endpoint for PCIe Receive
interface.
X-Ref Target - Figure 5-7
PIO_RX_ENGINE
m_axis_rx_tready
req_compl
req_td
requ_ep
clk
wr_en
rst_n
m_axis_rx_tdata
req_tc[2:0]
m_axis_rx_tstrb
req_attr[1:0]
m_axis_rx_tlast
req_len[9:0]
m_axis_rx_tvalid
req_rid[15:0]
m_axis_rx_tuser
req_tag[7:0]
compl_done
req_be[7:0]
req_addr[12:0]
wr_busy
wr_addr[10:0]
wr_be[7:0]
wr_data[31:0]
EP_RX
UG477_aA_05_020311
Figure 5-7:
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RX Engine
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The PIO_RX_ENGINE module receives and parses incoming read and write TLPs.
The RX engine parses one DWORD 32- and 64-bit addressable memory and I/O read
requests. The RX state machine extracts needed information from the TLP and passes it to
the memory controller, as defined in Table 5-4.
Table 5-4:
RX Engine: Read Outputs
Port
Description
req_compl
Completion Request
req_compl_wd
Completion Request with Data
req_td
Request TLP Digest bit
req_ep
Request Error Poisoning bit
req_tc[2:0]
Request Traffic Class
req_attr[1:0]
Request Attributes
req_len[9:0]
Request Length
req_rid[15:0]
Request Requester Identifier
req_tag[7:0]
Request Tag
req_be[7:0]
Request Byte Enable
req_addr[12:0]
Request Address
The RX Engine parses one DWORD 32- and 64-bit addressable memory and I/O write
requests. The RX state machine extracts needed information from the TLP and passes it to
the memory controller, as defined in Table 5-5.
Table 5-5:
RX Engine: Write Outputs
Port
Description
wr_en
Write received
wr_addr[10:0]
Write address
wr_be[7:0]
Write byte enable
wr_data[31:0]
Write data
The read datapath stops accepting new transactions from the core while the application is
processing the current TLP. This is accomplished by m_axis_rx_tready deassertion. For an
ongoing Memory or I/O Read transaction, the module waits for compl_done_i input to be
asserted before it accepts the next TLP, while an ongoing Memory or I/O Write transaction
is deemed complete after wr_busy_i is deasserted.
Transmit Path
Figure 5-8 shows the PIO_TX_ENGINE module. The datapath of the module must match the
datapath of the core being used. These modules connect with the core Transmit interface.
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X-Ref Target - Figure 5-8
PIO_TX_ENGINE
clk
rst_n
s_axis_rx_tready
requ_compl
req_td
req_ep
cfg_bus_mstr_enable
s_axis_tx_tdata
req_tc[2:0]
s_axis_tx_tstrb
req_attr[1:0]
s_axis_tx_tlast
req_len[9:0]
s_axis_tx_tvalid
req_rid[15:0]
tx_src_dsc
req_tag[7:0]
compl_done
req_be[7:0]
rd_addr[10:0]
rd_be[3:0]
req_addr[12:0]
rd_data[31:0]
completer_id[15:0]
EP_TX
Figure 5-8:
TX Engine
The PIO_TX_ENGINE module generates completions for received memory and I/O read
TLPs. The PIO design does not generate outbound read or write requests. However, you can
add this functionality to further customize the design.
The PIO_TX_ENGINE module generates completions in response to one DWORD 32- and
64-bit addressable memory and I/O read requests. Information necessary to generate the
completion is passed to the TX Engine, as defined in Table 5-6.
Table 5-6:
TX Engine Inputs
Port
Description
req_compl
Completion request (active-High)
req_td
Request TLP Digest bit
req_ep
Request Error Poisoning bit
req_tc[2:0]
Request Traffic Class
req_attr[1:0]
Request Attributes
req_len[9:0]
Request Length
req_rid[15:0]
Request Requester Identifier
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Table 5-6:
TX Engine Inputs (Cont’d)
Port
Description
req_tag[7:0]
Request Tag
req_be[7:0]
Request Byte Enable
req_addr[12:0]
Request Address
After the completion is sent, the TX engine asserts the compl_done_i output indicating to
the RX engine that it can assert m_axis_rx_tready and continue receiving TLPs.
Endpoint Memory
Figure 5-9 displays the PIO_EP_MEM_ACCESS module. This module contains the Endpoint
memory space.
X-Ref Target - Figure 5-9
PIO_EP_MEM_ACCESS
clk
rst_n
wr_en_i
rd_addr_i[10:0]
wr_busy_o
rd_be_i[3:0]
rd_data_o[31:0]
wr_addr_i[10:0]
wr_be_i[7:0]
wr_data_i[31:0]
EP_MEM
Figure 5-9:
EP Memory Access
The PIO_EP_MEM_ACCESS module processes data written to the memory from incoming
Memory and I/O Write TLPs and provides data read from the memory in response to
Memory and I/O Read TLPs.
The EP_MEM module processes one DWORD 32- and 64-bit addressable Memory and I/O
Write requests based on the information received from the RX Engine, as defined in
Table 5-7. While the memory controller is processing the write, it asserts the wr_busy_o
output indicating it is busy.
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Table 5-7:
EP Memory: Write Inputs
Port
Description
wr_en_i
Write received
wr_addr_i[10:0]
Write address
wr_be_i[7:0]
Write byte enable
wr_data_i[31:0]
Write data
Both 32- and 64-bit Memory and I/O Read requests of one DWORD are processed based on
the inputs defined in Table 5-8. After the read request is processed, the data is returned on
rd_data_o[31:0].
Table 5-8:
EP Memory: Read Inputs
Port
Description
req_be_i[7:0]
Request Byte Enable
req_addr_i[31:0]
Request Address
PIO Operation
PIO Read Transaction
Figure 5-10 depicts a Back-to-Back Memory Read request to the PIO design. The receive
engine deasserts m_axis_rx_tready as soon as the first TLP is completely received. The next
Read transaction is accepted only after compl_done_o is asserted by the transmit engine,
indicating that Completion for the first request was successfully transmitted.
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X-Ref Target - Figure 5-10
user_clk_out
m_axis_rx_tdata[63:0]
H1H0
m_axis_rx_tkeep[7:0]
FFh
--H2
H1H0
0Fh
--H3
FFh
0Fh
FFh
m_axis_rx_tlast
m_axis_rx_tvalid
m_axis_rx_tready
(rx_bar_hit[7:0])m_axis_rx_tuser[9:2]
00h
01h
00h
01h
00h
TLP2
TLP1
compl_done_o
s_axis_tx_tdata[63:0]
s_axis_tx_tkeep[7:0]
H1H0
D0H2
FF
s_axis_tx_tlast
s_axis_tx_tvalid
(src_dsc)s_axis_tx_tuser[3]
s_axis_tx_tready
Figure 5-10:
Back-to-Back Read Transactions
PIO Write Transaction
Figure 5-11 depicts a back-to-back Memory Write to the PIO design. The next Write
transaction is accepted only after wr_busy_o is deasserted by the memory access unit,
indicating that data associated with the first request was successfully written to the
memory aperture.
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X-Ref Target - Figure 5-11
user_clk_out
m_axis_rx_tdata[63:0]
H1H0
m_axis_rx_tkeep[7:0]
FFh
D0H2
FFh
H1H0
D0H3
FFh
FFh
FFh
m_axis_rx_tlast
m_axis_rx_tvalid
m_axis_rx_tready
(rx_bar_hit[7:0])m_axis_rx_tuser[9:2]
00h
01h
00h
01h
00h
TLP1
TLP2
wr_busy_o
compl_done_o
s_axis_tx_tdata[63:0]
s_axis_tx_tkeep[7:0]
s_axis_tx_tlast
s_axis_tx_tvalid
(src_dsc)s_axis_tx_tuser[3]
s_axis_tx_tready
Figure 5-11:
Back-to-Back Write Transactions
Device Utilization
Table 5-9 shows the PIO design FPGA resource utilization.
Table 5-9:
PIO Design FPGA Resources
Resources
Utilization
LUTs
300
Flip-Flops
500
Block RAMs
4
Summary
The PIO design demonstrates the Endpoint for PCIe and its interface capabilities. In
addition, it enables rapid bring-up and basic validation of end user Endpoint add-in card
FPGA hardware on PCI Express platforms. You can leverage standard operating system
utilities that enable generation of read and write transactions to the target space in the
reference design.
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Configurator Example Design
The Configurator example design, included with the 7 Series FPGAs Integrated Block for PCI
Express® in Root Port configuration generated by the Vivado IDE, is a synthesizable,
lightweight design that demonstrates the minimum setup required for the integrated block
in Root Port configuration to begin application-level transactions with an Endpoint.
System Overview
PCI Express devices require setup after power-on, before devices in the system can begin
application specific communication with each other. At least two devices connected
through a PCI Express Link must have their Configuration spaces initialized and be
enumerated to communicate.
Root Ports facilitate PCI Express enumeration and configuration by sending Configuration
Read (CfgRd) and Write (CfgWr) TLPs to the downstream devices such as Endpoints and
Switches to set up the configuration spaces of those devices. When this process is
complete, higher-level interactions, such as Memory Reads (MemRd TLPs) and Writes
(MemWr TLPs), can occur within the PCI Express System.
The Configurator example design described here performs the configuration transactions
required to enumerate and configure the Configuration space of a single connected PCI
Express Endpoint and allow application-specific interactions to occur.
Configurator Example Design Hardware
The Configurator example design consists of four high-level blocks:
•
Root Port: The 7 series FPGAs integrated block in Root Port configuration.
•
Configurator Block: Logical block which interacts with the configuration space of a
PCI Express Endpoint device connected to the Root Port.
•
Configurator ROM: Read-only memory that sources configuration transactions to the
Configurator Block.
•
PIO Master: Logical block which interacts with the user logic connected to the
Endpoint by exchanging data packets and checking the validity of the received data.
The data packets are limited to a single DWORD and represent the type of traffic that
would be generated by a CPU.
Note: The Configurator Block, Configurator ROM, and Root Port are logically grouped in the RTL
code within a wrapper file called the Configurator Wrapper.
The Configurator example design, as delivered, is designed to be used with the PIO Slave
example included with Xilinx Endpoint cores and described in Chapter 6, Test Benches. The
PIO Master is useful for simple bring-up and debugging, and is an example of how to
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interact with the Configurator Wrapper. The Configurator example design can be modified
to be used with other Endpoints.
Figure 5-12 shows the various components of the Configurator example design.
X-Ref Target - Figure 5-12
Configurator
PIO Master
Data
Checker
Controller
Completion
Decoder
5.0 Gb/s
(Gen2)
Enabler
7 Series FPGAs
Integrated Block
for PCI Express
(Configured as
Root Port)
Controller
Packet
Generator
Packet
Generator
TX Mux
Figure 5-12:
Configurator Example Design Components
Figure 5-13 shows how the blocks are connected in an overall system view.
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X-Ref Target - Figure 5-13
Configurator Example Design
PIO Master
AXI4-Stream Interface Pass-Through
Configurator
Wrapper
Configurator
Block
Configurator
ROM
AXI4-Stream Interface
Integrated Root Port
Root Port
DUT for
PCI Express
PCI Express Fabric
Integrated
Endpoint
Model
PIO Slave
Endpoint
Design
Figure 5-13:
Configurator Example Design
Configurator Block
The Configurator Block generates CfgRd and CfgWr TLPs and presents them to the
AXI4-Stream interface of the integrated block in Root Port configuration. The TLPs that the
Configurator Block generates are determined by the contents of the Configurator ROM.
The generated configuration traffic is predetermined by you to address your particular
system requirements. The configuration traffic is encoded in a memory-initialization file
(the Configurator ROM) which is synthesized as part of the Configurator. The Configurator
Block and the attached Configurator ROM is intended to be usable a part of a real-world
embedded design.
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The Configurator Block steps through the Configuration ROM file and sends the TLPs
specified therein. Supported TLP types are Message, Message w/Data, Configuration Write
(Type 0), and Configuration Read (Type 0). For the Configuration packets, the Configurator
Block waits for a Completion to be returned before transmitting the next TLP. If the
Completion TLP fields do not match the expected values, PCI Express configuration fails.
However, the Data field of Completion TLPs is ignored and not checked
Note: There is no completion timeout mechanism in the Configurator Block, so if no Completion is
returned, the Configurator Block waits forever.
The Configurator Block has these parameters, which you can modify:
•
TCQ: Clock-to-out delay modeled by all registers in design.
•
EXTRA_PIPELINE: Controls insertion of an extra pipeline stage on the Receive
AXI4-Stream interface for timing.
•
ROM_FILE: File name containing conf iguration steps to perform.
•
ROM_SIZE: Number of lines in ROM_FILE containing data (equals number of TLPs to
send/2).
•
REQUESTER_ID: Value for the Requester ID field in outgoing TLPs.
When the Configurator Block design is used, all TLP traffic must pass through the
Configurator Block. The user design is responsible for asserting the start_config input (for
one clock cycle) to initiate the configuration process when user_lnk_up has been asserted
by the core. Following start_config, the Configurator Block performs whatever
configuration steps have been specified in the Configuration ROM. During configuration,
the Configurator Block controls the core AXI4-Stream interface. Following configuration, all
AXI4-Stream traffic is routed to/from the user application, which in the case of this example
design is the PIO Master. The end of configuration is signaled by the assertion of
finished_config. If configuration is unsuccessful for some reason, failed_config is also
asserted.
If used in a system that supports PCIe® v2.2 5.0 Gb/s links, the Configurator Block begins
its process by attempting to up-train the link from 2.5 Gb/s to 5.0 Gb/s. This feature is
enabled depending on the LINK_CAP_MAX_LINK_SPEED parameter on the Configurator
Wrapper.
The Configurator does not support the user throttling received data on the Receive
AXI4-Stream interface. Because of this, the Root Port inputs which control throttling are not
included on the Configurator Wrapper. These signals are m_axis_rx_tready and
rx_np_ok. This is a limitation of the Configurator example design and not of the core in
Root Port configuration. This means that the user design interfacing with the Configurator
example design must be able to accept received data at line rate.
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Configurator ROM
The Configurator ROM stores the necessary configuration transactions to configure a PCI
Express Endpoint. This ROM interfaces with the Configurator Block to send these
transactions over the PCI Express link.
The example ROM file included with this design shows the operations needed to configure
a 7 Series FPGAs Integrated Endpoint Block for PCI Express and PIO Example Design.
The Configurator ROM can be customized for other Endpoints and PCI Express system
topologies. The unique set of configuration transactions required depends on the Endpoint
that interacts with the Root Port. This information can be obtained from the documentation
provided with the Endpoint.
The ROM file follows the format specified in the Verilog specification (IEEE 1364-2001)
section 17.2.8, which describes using the $readmemb function to pre-load data into a RAM
or ROM. Verilog-style comments are allowed.
The file is read by the simulator or synthesis tool and each memory value encountered is
used as a single location in memory. Digits can be separated by an underscore character (_)
for clarity without constituting a new location.
Each configuration transaction specified uses two adjacent memory locations:
•
The first location specifies the header fields. Header fields are on even addresses.
•
The second location specifies the 32-bit data payload. (For CfgRd TLPs and Messages
without data, the data location is unused but still present.) Data payloads are on odd
addresses.
For headers, Messages and CfgRd/CfgWr TLPs use different fields. For all TLPs, two bits
specify the TLP type. For Messages, Message Routing and Message Code are specified. For
CfgRd/CfgWr TLPs, Function Number, Register Number, and 1st DWORD Byte-Enable are
specified. The specific bit layout is shown in the example ROM file.
PIO Master
The PIO Master demonstrates how a user application design might interact with the
Configurator Block. It directs the Configurator Block to bring up the link partner at the
appropriate time, and then (after successful bring-up) generates and consumes bus traffic.
The PIO Master performs writes and reads across the PCI Express Link to the PIO Slave
Example Design (from the Endpoint core) to confirm basic operation of the link and the
Endpoint.
The PIO Master waits until user_lnk_up is asserted by the Root Port. It then asserts
start_config to the Configurator Block. When the Configurator Block asserts
finished_config, the PIO Master writes and reads to/from each BAR in the PIO Slave design.
If the readback data matches what was written, the PIO Master asserts its
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pio_test_finished output. If there is a data mismatch or the Configurator Block fails to
configure the Endpoint, the PIO Master asserts its pio_test_failed output. The PIO
Master operation can be restarted by asserting its pio_test_restart input for one clock
cycle.
Configurator File Structure
Table 5-10 defines the Configurator example design file structure.
Table 5-10:
Example Design File Structure
File
Description
xilinx_pcie_2_1_rport_7x.v
Top-level wrapper file for Configurator example design
cgator_wrapper.v
Wrapper for Configurator and Root Port
cgator.v
Wrapper for Configurator sub-blocks
cgator_cpl_decoder.v
Completion decoder
cgator_pkt_generator.v
Configuration TLP generator
cgator_tx_mux.v
Transmit AXI4-Stream muxing logic
cgator_controller.v
Configurator transmit engine
cgator_cfg_rom.data
Configurator ROM file
pio_master.v
Wrapper for PIO Master
pio_master_controller.v
TX and RX Engine for PIO Master
pio_master_checker.v
Checks incoming User-Application Completion TLPs
pio_master_pkt_generator.v
Generates User-Application TLPs
The hierarchy of the Configurator example design is:
xilinx_pcie_2_1_rport_7x
•
topdirectory
cgator_wrapper
°
°
pcie_2_1_rport_7x (in the source directory)
This directory contains all the source files for the core in Root Port Configuration.
cgator
-
cgator_cpl_decoder
-
cgator_pkt_generator
-
cgator_tx_mux
•
cgator_controller
This directory contains <cgator_cfg_rom.data> (specified by ROM_FILE)*
pio_master
°
pio_master_controller
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°
pio_master_checker
°
pio_master_pkt_generator
Note: cgator_cfg_rom.data is the default name of the ROM data file. You can override this by
changing the value of the ROM_FILE parameter.
Summary
The Configurator example design is a synthesizable design that demonstrates the
capabilities of the 7 Series FPGAs Integrated Block for PCI Express when configured as a
Root Port. The example is provided through the Vivado IDE and uses the Endpoint PIO
example as a target for PCI Express enumeration and configuration. The design can be
modified to target other Endpoints by changing the contents of a ROM file.
Generating the Core
To generate a core using the default values in the Vivado IDE, follow these steps:
1. Start the Vivado IP catalog.
2. Select File > New Project.
3. Enter a project name and location, then click Next. This example uses
project_name.cpg and project_dir.
4. In the New Project wizard pages, do not add sources, existing IP, or constraints.
5. From the Part tab (Figure 5-14), select these options:
°
Family: Virtex7
°
Device: xc7v485t
°
Package: ffg1157
°
Speed Grade: -3
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Note: If an unsupported silicon device is selected, the core is grayed out (unavailable) in the list
of cores.
X-Ref Target - Figure 5-14
Figure 5-14:
Default Part
6. In the final project summary page, click OK.
7. In the Vivado IP catalog, expand Standard Bus Interfaces > PCI Express, and
double-click the 7 Series Integrated Block for PCI Express core to display the
Customize IP dialog box.
8. In the Component Name field, enter a name for the core.
Note: <component_name> is used in this example.
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X-Ref Target - Figure 5-15
Figure 5-15:
Integrated Block Core Configuration Parameters
9. From the Device/Port Type drop-down menu, select the appropriate device/port type of
the core (Endpoint or Root Port).
10. Click OK to generate the core using the default parameters.
11. In the Design sources tab, right-click the XCI file, and select Generate.
12. Select All to generate the core with the default parameters.
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Simulating the Example Design
The example design provides a quick way to simulate and observe the behavior of the core
for PCI Express Endpoint and Root Port Example design projects generated using the Vivado
Design Suite.
The currently supported simulators are:
•
Vivado simulator (default)
•
ModelSim QuestaSim
Note: ModelSim PE 10.2a is not supported.
•
Cadence IES
•
Synopsys VCS
The simulator uses the example design test bench and test cases provided along with the
example design for both of the design configurations.
For any project (PCI Express core) generated out of the box, the simulation using the default
Vivado simulator can be run as follows:
1. In the Sources Window, right-click the example project file (.xci), and select Open IP
Example Design.
The example project is created.
2. In the Flow Navigator (left-hand pane), under Simulation, right-click Run Simulation
and select Run Behavioral Simulation.
IMPORTANT: The post-synthesis and post-implementation simulation options are not supported for the
PCI Express block.
After the Run Behavioral Simulation Option is running, you can observe the compilation
and elaboration phase through the activity in the Tcl Console, and in the Simulation tab
of the Log Window.
3. In Tcl Console, type the run all command and press Enter. This runs the complete
simulation as per the test case provided in example design test bench.
After the simulation is complete, the result can be viewed in the Tcl Console.
In Vivado IDE, change the simulation settings as follows:
1. In the Flow Navigator, under Simulation, select Simulation Settings.
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2. Set the Target simulator to QuestaSim/ModelSim Simulator, Incisive Enterprise
Simulator (IES) or Verilog Compiler Simulator.
3. In the simulator tab, select Run Simulation > Run behavioral simulation.
4. When prompted, click Yes to change and then run the simulator.
IMPORTANT: Simulation is not supported for configurations with the Silicon Revision option set to
Initial_ES. Only implementation is supported. If simulation is performed, it results in DRP monitor
errors.
Endpoint Configuration
The simulation environment provided with the 7 Series FPGAs Integrated Block for
PCI Express core in Endpoint configuration performs simple memory access tests on the
PIO example design. Transactions are generated by the Root Port Model and responded to
by the PIO example design.
•
PCI Express transaction layer packets (TLPs) are generated by the test bench transmit
user application (pci_exp_usrapp_tx). As it transmits TLPs, it also generates a log
file, tx.dat.
•
PCI Express TLPs are received by the test bench receive user application
(pci_exp_usrapp_rx). As the user application receives the TLPs, it generates a log
file, rx.dat.
For more information about the test bench, see Root Port Model Test Bench for Endpoint in
Chapter 6.
Synthesizing and Implementing the Example Design
To run synthesis and implementation on the example design:
1. Right-click the XCI file, and select Open IP example design.
A new Vivado IDE window opens with the project name example_project within the project
directory.
2. In the Flow Navigator, click Run Synthesis and Run Implementation.
TIP: Click Run Implementation to run both synthesis and implementation.
Click Generate Bitstream to run synthesis, implementation, and then generate the bitstream.
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Directory and File Contents
The 7 Series FPGAs Integrated Block for PCI Express example design directories and
associated files are defined in the sections that follow. When core is generated in Vivado
IDE, the directory structure generated differs for Endpoint design and Root port design, as
explained below.
The project name and the component name can be customized; however, the default
project name is project_1 and the default component name is pcie_7x_0.
IMPORTANT: The default project and component names are used in this explanation of the example
design.
Endpoint Solution
The Endpoint Solution directory structure is shown Figure 5-16.
Note: The files indicated by [vhd] are also generated with the VHDL version of the core, with a .vhd
extension.
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project_1/project_1.src/sources_1/ip/pcie_7x_0
This is the main directory for all directories. The name of the directory is project_1, by
default.
pcie_7x_0
This is the directory created based on the component name specified. By default this
directory is pcie_7x_0. This directory consists of three subdirectories: source,
simulation and example_design. These are described in detail in the following
sections.
source
This directory contains the core top-level module definition. This module is instantiated in
the Vivado Design Suite-generated top-level wrapper file, which exists in the sim and
synth directories, in parallel to this directory.
File name (Verilog format): pcie_7x_<version_number>_top.v.
For example: pcie_7x_v2_1_top.v.
File name (VHDL format): pcie_7x_<version_number>_top.vhd.
For example: pcie_7x_v2_1_top.vhd.
IMPORTANT: The parameters listed in the top-level file are being driven directly by the Vivado Design
Suite generated top-level synthesis wrapper using the customization in the Vivado IDE parameters.
However, the parameters from the top-level file are not passed to the core_top.v/core_top.vhd
module. Instead, the core top module is automatically assigned the parameters from the Vivado IDE.
To check that the proper parameter values are being driven, refer to the core_top module.
sim
This directory contains the Vivado Design Suite-generated top-level wrapper file used for
simulation. The file name is based on the component name you have specified. The default
name is pcie_7x_0.v. This file contains the core top-level module definition which
instantiates the module pcie_7x_<version_number>_top.v or
pcie_7x_<version_number>_top.vhd.
synth
This directory contains the Vivado Design Suite-generated top-level wrapper file used for
synthesis. The file name is based the component name you have specified. The default
name is pcie_7x_0.v. This file contains the core top-level module definition which
instantiates the module pcie_7x_<version_number>_top.v or
pcie_7x_<version_number>_top.vhd.
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pcie_7x_0/source
This directory contains all source files for the PCI Express core.
Table 5-11:
pcie_7x_0/source Directory
Name
pcie_7x_0_core_top.v [vhd]
Description
PCIe core top file. Contains the instances of pcie_top and
gt_top.
pcie_7x_0_axi_basic_rx_null_gen.v [vhd]
pcie_7x_0_axi_basic_rx_pipeline.v [vhd]
pcie_7x_0_axi_basic_rx.v [vhd]
pcie_7x_0_axi_basic_top.v [vhd]
pcie_7x_0_axi_basic_tx_pipeline.v [vhd]
AXI4-Stream interface modules for the 7 series FPGA
Integrated Block for PCI Express.
pcie_7x_0_axi_basic_tx_thrtl_ctl.v [vhd]
pcie_7x_0_axi_basic_tx.v [vhd]
pcie_7x_0_gt_top.v [vhd]
pcie_7x_0_gtp_pipe_drp.v
pcie_7x_0_gtp_pipe_rate.v
pcie_7x_0_gtp_pipe_reset.v
pcie_7x_0_gt_rx_valid_filter_7x.v
pcie_7x_0_gt_wrapper.v
pcie_7x_0_pipe_clock.v
pcie_7x_0_pipe_drp.v
pcie_7x_0_pipe_eq.v
pcie_7x_0_pipe_rate.v
GTX and GTP Wrapper files for the 7 series FPGA Integrated
Block for PCI Express.
pcie_7x_0_pipe_reset.v
pcie_7x_0_pipe_sync.v
pcie_7x_0_pipe_user.v
pcie_7x_0_pipe_wrapper.v
pcie_7x_0_qpll_drp.v
pcie_7x_0_qpll_reset.v
pcie_7x_0_qpll_wrapper.v
pcie_7x_0_rxeq_scan.v
pcie_7x_0_pcie_bram_7x.v [vhd]
pcie_7x_0_pcie_brams_7x.v [vhd]
pcie_7x_0_pcie_bram_top_7x.v [vhd]
pcie_7x_0_pcie_top.v [vhd]
pcie_7x_0_pcie_7x.v [vhd]
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Table 5-11:
pcie_7x_0/source Directory (Cont’d)
Name
Description
pcie_7x_0_pcie_pipe_lane.v [vhd]
pcie_7x_0_pcie_pipe_misc.v [vhd]
PIPE module for the 7 series FPGA integrated Block for PCIe.
pcie_7x_0_pcie_pipe_pipeline.v [vhd]
pcie_7x_0_clocks.xdc
Contains all clock constraints required for the Out Of Context
(OOC) flow
pcie_7x_0_ooc.xdc
Out-of-context XDC file.
pcie_7x_0-PCIE_X0Y0.xdc
PCIe core-level XDC file.
pcie_7x_0/example_design
This directory contains all the example design files required for the example_design.
Table 5-12:
pcie_7x_0/example_design Directory
Name
EP_MEM.v [vhd]
Description
PIO Example design files
pcie_app_7x.v [vhd]
PIO_EP_MEM_ACCESS.v [vhd]
PIO_EP.v [vhd]
PIO_RX_ENGINE.v [vhd]
PIO_TO_CTRL.v [vhd]
PIO_TX_ENGINE.v [vhd]
PIO.v [vhd]
xilinx_pcie_2_1_ep_7x.v [vhd]
Xilinx example design top-level file. It contains the
instances of the pipe_clock block PIO design top module
and core top module (wrapper generated by Vivado
Design Suite).
xilinx_pcie_7x_ep_x8g2.xdc
XDC file for example design. The file name reflects the
link width and speed configured in the Vivado IDE.
pcie_7x_0/simulation
This directory contains all the simulation related files. This directory consists of three
subdirectories: dsport, functional and tests.
pcie_7x_0/hierarchy.txt
This text file explains the hierarchy of the entire example design with the names of the files
down the hierarchy.
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pcie_7x_0/simulation/dsport
This directory contains the dsport model files.
Table 5-13:
pcie_7x_0/simulation/dsport Directory
Name
Description
pcie_2_1_rport_7x.v [vhd]
pcie_axi_trn_bridge.v [vhd]
pci_exp_expect_tasks.vh
pci_exp_usrapp_cfg.v [vhd]
pci_exp_usrapp_com.v [vhd]
Root port models files
pci_exp_usrapp_pl.v [vhd]
pci_exp_usrapp_rx.v [vhd]
pci_exp_usrapp_tx.v [vhd]
xilinx_pcie_2_1_rport_7x.v [vhd]
pcie_7x_0/simulation/functional
This directory consists of the top-level test bench and clock generation modules.
Table 5-14:
pcie_7x_0/simulation/functional Directory
Name
Description
board_common.vh
Contains test bench definitions.
board.v [vhd]
Top-level test bench file.
sys_clk_gen_ds.v [vhd]
System differential clock source.
sys_clk_gen.v [vhd]
System clock source.
pcie_7x_0/simulation/tests
This directory consists of the test cases.
Table 5-15:
pcie_7x_0/simulation/tests Directory
Name
sample_tests.vh
tests.vh
Description
Test definition for example test bench.
Root Port Solution
The Root Port Solution directory structure is shown in Figure 5-17. The file directory
structure is same as Endpoint solution except the simulation directory.
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Note: The files indicated by [vhd] are also generated with the VHDL version of the core, with a .vhd
extension.
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project_1/project_1.src/sources_1/ip/pcie_7x_0
This is the main directory for all directories. The name of the directory is project_1, by
default.
pcie_7x_0
This directory is created based on the component name specified. By default this directory
is pcie_7x_0. It consists of three subdirectories: source, simulation and
example_design. These are described in detail in the following sections.
source
This directory contains the core top-level module definition. This module is instantiated in
the Vivado Design Suite-generated top-level wrapper file, which exists in the sim and
synth directories, in parallel to this directory.
File name (Verilog format): pcie_7x_<version_number>_top.v.
For example: pcie_7x_v2_1_top.v.
File name (VHDL format): pcie_7x_<version_number>_top.vhd.
For example: pcie_7x_v2_1_top.vhd.
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IMPORTANT: The parameters listed in the top-level file are being driven directly by the Vivado Design
Suite generated top-level synthesis wrapper as per the customization in the Vivado IDE parameters.
However, the parameters from the top-level file are not passed to the core_top.v/core_top.vhd
module. Instead, the core top module is automatically assigned the parameters as per the Vivado IDE
parameters. To check that the proper parameter values are being driven, refer to the core_top
module.
sim
This directory contains the Vivado Design Suite-generated top-level wrapper file used for
simulation. The file name is based on the component name you have specified. The default
name is pcie_7x_0.v. This file contains the core top-level module definition which
instantiates the module pcie_7x_<version_number>_top.v or
pcie_7x_<version_number>_top.vhd.
synth
This directory contains the Vivado Design Suite-generated top-level wrapper file used for
synthesis. The file name is based the component name you have specified. The default
name is pcie_7x_0.v. This file contains the core top-level module definition which
instantiates the module pcie_7x_<version_number>_top.v or
pcie_7x_<version_number>_top.vhd.
pcie_7x_0/source
This directory contains all source files for the PCI Express core.
Table 5-16:
pcie_7x_0/source Directory
Name
pcie_7x_0_core_top.v [vhd]
Description
PCIe core top file. Contains the instances of pcie_top and
gt_top.
pcie_7x_0_axi_basic_rx_null_gen.v [vhd]
pcie_7x_0_axi_basic_rx_pipeline.v [vhd]
pcie_7x_0_axi_basic_rx.v [vhd]
pcie_7x_0_axi_basic_top.v [vhd]
pcie_7x_0_axi_basic_tx_pipeline.v [vhd]
AXI4-Stream interface modules for the 7 series FPGA
Integrated Block for PCI Express.
pcie_7x_0_axi_basic_tx_thrtl_ctl.v [vhd]
pcie_7x_0_axi_basic_tx.v [vhd]
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Table 5-16:
pcie_7x_0/source Directory (Cont’d)
Name
Description
pcie_7x_0_gt_top.v [vhd]
pcie_7x_0_gtp_pipe_drp.v
pcie_7x_0_gtp_pipe_rate.v
pcie_7x_0_gtp_pipe_reset.v
pcie_7x_0_gt_rx_valid_filter_7x.v
pcie_7x_0_gt_wrapper.v
pcie_7x_0_pipe_clock.v
pcie_7x_0_pipe_drp.v
pcie_7x_0_pipe_eq.v
pcie_7x_0_pipe_rate.v
GTX and GTP Wrapper files for the 7 series FPGA Integrated
Block for PCI Express.
pcie_7x_0_pipe_reset.v
pcie_7x_0_pipe_sync.v
pcie_7x_0_pipe_user.v
pcie_7x_0_pipe_wrapper.v
pcie_7x_0_qpll_drp.v
pcie_7x_0_qpll_reset.v
pcie_7x_0_qpll_wrapper.v
pcie_7x_0_rxeq_scan.v
pcie_7x_0_pcie_bram_7x.v [vhd]
pcie_7x_0_pcie_brams_7x.v [vhd]
pcie_7x_0_pcie_bram_top_7x.v [vhd]
pcie_7x_0_pcie_top.v [vhd]
pcie_7x_0_pcie_7x.v [vhd]
pcie_7x_0_pcie_pipe_lane.v [vhd]
pcie_7x_0_pcie_pipe_misc.v [vhd]
pcie_7x_0_pcie_pipe_pipeline.v [vhd]
Block RAM modules for the 7 series FPGA Integrated Block
for PCI Express.
PCIe core wrapper files.
PIPE module for the 7 series FPGA integrated Block for PCI
Express.
pcie_7x_0_clocks.xdc
Contains all clock constraints required for the out-of-context
(OOC) flow.
pcie_7x_0_ooc.xdc
OOC XDC file.
pcie_7x_0-PCIE_X0Y0.xdc
PCIe core-level XDC file.
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pcie3_7x_0/example_design
This directory contains all the example design files required for the example_design.
Table 5-17:
pcie_7x_0/example_design Directory
Name
Description
cgator_cfg_rom.data
cgator_controller.v [vhd]
cgator_cpl_decoder.v [vhd]
cgator_gen2_enabler.v [vhd]
cgator_pkt_generator.v [vhd]
Configurator block files.
cgator_tx_mux.v [vhd]
cgator.v [vhd]
cgator_wrapper.v [vhd]
pio_master_checker.v [vhd]
pio_master_controller.v [vhd]
pio_master_pkt_generator.v [vhd]
PIO example design files.
pio_master.v [vhd]
xilinx_pcie_2_1_rport_7x.v [vhd]
Example design top-level file. This consists of the
instances of PIO master and the core top file.
xilinx_pcie_7x_rp_x8g2.xdc
XDC file for example design. The file name reflects the
link width and speed configured in the Vivado IDE.
pcie_7x_0/simulation/ep
This directory contains the Endpoint (EP) model files.
Table 5-18:
pcie_7x_0/simulation/ep Directory
Name
Description
EP_MEM.v [vhd]
pcie_2_1_ep_7x.v [vhd]
pcie_app_7vx.v[vhd]
PIO_EP_MEM_ACCESS.v[vhd]
PIO_EP.v[vhd]
EP model files.
PIO_RX_ENGINE.v[vhd]
PIO_TO_CTRL.v[vhd]
PIO_TX_ENGINE.v[vhd]
PIO.v[vhd]
xilinx_pcie_2_1_ep_7x.v[vhd]
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pcie_7x_0/simulation/functional
This directory consists of the top-level test bench and clock generation modules.
Table 5-19:
pcie_7x_0/simulation/functional Directory
Name
Description
board.v[vhd]
Top-level test bench file.
sys_clk_gen.v[vhd]
System clock generator file.
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Chapter 6
Test Benches
This chapter contains information about the test benches provided in the Vivado® Design
Suite environment.
Root Port Model Test Bench for Endpoint
The PCI Express® Root Port Model is a robust test bench environment that provides a test
program interface that can be used with the provided PIO design or with a user design. The
purpose of the Root Port Model is to provide a source mechanism for generating
downstream PCI Express TLP traffic to stimulate your design, and a destination mechanism
for receiving upstream PCI Express TLP traffic from your design in a simulation
environment.
Source code for the Root Port Model is included to provide the model for a starting point
for your test bench. All the significant work for initializing configuration space, creating TLP
transactions, generating TLP logs, and providing an interface for creating and verifying
tests are complete, allowing you to dedicate efforts to verifying the correct functionality of
the design rather than spending time developing an Endpoint core test bench
infrastructure.
The Root Port Model consists of:
•
Test Programming Interface (TPI), which allows you to stimulate the Endpoint device for
the model
•
Example tests that illustrate how to use the test program TPI.
•
Verilog or VHDL source code for all Root Port Model components, which allow you to
customize the test bench.
Figure 6-1 illustrates the Root Port Model coupled with the PIO design.
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X-Ref Target - Figure 6-1
Output
Logs
Root Port
Model TPI for
PCI Express
usrapp_com
Test
Program
usrapp_tx
usrapp_rx
dsport
PCI Express Fabric
Endpoint Core for
PCI Express
PIO
Design
Endpoint DUT for PCI Express
Figure 6-1:
Root Port Model and Top-Level Endpoint
Architecture
The Root Port Model consists of these blocks, illustrated in Figure 6-1:
•
dsport (Root Port)
•
usrapp_tx
•
usrapp_rx
•
usrapp_com (Verilog only)
The usrapp_tx and usrapp_rx blocks interface with the dsport block for transmission and
reception of TLPs to/from the Endpoint Design Under Test (DUT). The Endpoint DUT
consists of the Endpoint for PCIe and the PIO design (displayed) or customer design.
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The usrapp_tx block sends TLPs to the dsport block for transmission across the PCI Express
Link to the Endpoint DUT. In turn, the Endpoint DUT device transmits TLPs across the PCI
Express Link to the dsport block, which are subsequently passed to the usrapp_rx block. The
dsport and core are responsible for the data link layer and physical link layer processing
when communicating across the PCI Express logic. Both usrapp_tx and usrapp_rx utilize the
usrapp_com block for shared functions, for example, TLP processing and log file outputting.
Transaction sequences or test programs are initiated by the usrapp_tx block to stimulate the
logic interface of the Endpoint device. TLP responses from the Endpoint device are received
by the usrapp_rx block. Communication between the usrapp_tx and usrapp_rx blocks allow
the usrapp_tx block to verify correct behavior and act accordingly when the usrapp_rx block
has received TLPs from the Endpoint device.
Simulating the Example Design
To simulate the design, see Simulating the Example Design, page 289.
Scaled Simulation Timeouts
The simulation model of the 7 Series FPGAs Integrated Block for PCI Express uses scaled
down times during link training to allow for the link to train in a reasonable amount of time
during simulation. According to the PCI Express Specification, rev. 2.1 [Ref 2], there are
various timeouts associated with the link training and status state machine (LTSSM) states.
The 7 series FPGAs integrated block scales these timeouts by a factor of 256 in simulation,
except in the Recovery Speed_1 LTSSM state, where the timeouts are not scaled.
Test Selection
Table 6-1 describes the tests provided with the Root Port Model, followed by specific
sections for VHDL and Verilog test selection.
Table 6-1:
Root Port Model Provided Tests
Test Name
sample_smoke_test0
Test in
VHDL/Verilog
Description
Verilog and
VHDL
Issues a PCI Type 0 Configuration Read TLP and waits for the
completion TLP; then compares the value returned with the expected
Device/Vendor ID value.
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Table 6-1:
Root Port Model Provided Tests (Cont’d)
Test Name
sample_smoke_test1
pio_writeReadBack_test0
Test in
VHDL/Verilog
Description
Verilog
Performs the same operation as sample_smoke_test0 but makes use of
expectation tasks. This test uses two separate test program threads:
• the first thread issues the PCI Type 0 Configuration Read TLP, and
• the second thread issues the Completion with Data TLP expectation
task.
This test illustrates the form for a parallel test that uses expectation
tasks. This test form enables for you to confirm the receipt of any TLPs
from your design. Additionally, this method can be used to confirm
reception of TLPs when ordering is unimportant.
Verilog and
VHDL
Performs a check for the expected Device/Vendor ID, Link Speed, and
Link Width value. Performs Endpoint enumeration (scan and program
BARs, and set PCIe configuration registers. Issues Memory/IO Write
and Read packets depending on the BAR type enabled (IO, Memory
32-bit, or Memory 64-bit) and checks that the written value can be
read back successfully.
Output Logging
When a test fails on the example or customer design, the test programmer debugs the
offending test case. Typically, the test programmer inspects the wave file for the simulation
and cross-reference this to the messages displayed on the standard output. Because this
approach can be very time consuming, the Root Port Model offers an output logging
mechanism to assist the tester with debugging failing test cases to speed the process.
The Root Port Model creates three output log files during each simulation run.
•
rx.dat and tx.dat. These log files each contain a detailed record of every TLP that was
received and transmitted, respectively, by the Root Port Model. When you understand
the expected TLP transmission during a specific test case, you can more easily isolate
the failure.
•
error.dat. This log file is used in conjunction with the expectation tasks. Test programs
that use the expectation tasks generate a general error message to standard output.
Detailed information about the specific comparison failures that have occurred due to
the expectation error is located within error.dat.
Parallel Test Programs
There are two classes of tests supported by the Root Port Model:
•
Sequential tests. Tests that exist within one process and behave similarly to sequential
programs. The test depicted in Test Program: pio_writeReadBack_test0, page 306 is an
example of a sequential test. Sequential tests are very useful when verifying behavior
that have events with a known order.
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•
Parallel tests. Tests involving more than one process thread. The test
sample_smoke_test1 is an example of a parallel test with two process threads.
Parallel tests are very useful when verifying that a specific set of events have occurred,
however the order of these events are not known.
A typical parallel test uses the form of one command thread and one or more expectation
threads. These threads work together to verify the device functionality. The role of the
command thread is to create the necessary TLP transactions that cause the device to receive
and generate TLPs. The role of the expectation threads is to verify the reception of an
expected TLP. The Root Port Model TPI has a complete set of expectation tasks to be used
in conjunction with parallel tests.
Because the example design is a target-only device, only Completion TLPs can be expected
by parallel test programs while using the PIO design. However, the full library of expectation
tasks can be used for expecting any TLP type when used in conjunction with the user design
(which can include bus-mastering functionality). Currently, the VHDL version of the Root
Port Model Test Bench does not support Parallel tests.
Test Description
The Root Port Model provides a Test Program Interface (TPI). The TPI provides the means to
create tests by invoking a series of Verilog tasks. All Root Port Model tests should follow the
same six steps:
1. Perform conditional comparison of a unique test name.
2. Set up master timeout in case simulation hangs.
3. Wait for Reset and link-up.
4. Initialize the configuration space of the Endpoint.
5. Transmit and receive TLPs between the Root Port Model and the Endpoint DUT.
6. Verify that the test succeeded.
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Test Program: pio_writeReadBack_test0
1.
2.
3.
4.
5.
6.
7.
8.
9.
10.
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12.
13.
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15.
16.
17.
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else if(testname == "pio_writeReadBack_test1"
begin
// This test performs a 32 bit write to a 32 bit Memory space and performs a read back
TSK_SIMULATION_TIMEOUT(10050);
TSK_SYSTEM_INITIALIZATION;
TSK_BAR_INIT;
for (ii = 0; ii <= 6; ii = ii + 1) begin
if (BAR_INIT_P_BAR_ENABLED[ii] > 2'b00) // bar is enabled
case(BAR_INIT_P_BAR_ENABLED[ii])
2'b01 : // IO SPACE
begin
$display("[%t] : NOTHING: to IO 32 Space BAR %x", $realtime, ii);
end
2'b10 : // MEM 32 SPACE
begin
$display("[%t] : Transmitting TLPs to Memory 32 Space BAR %x",
$realtime, ii);
//-----------------------------------------------------------------------// Event : Memory Write 32 bit TLP
//-----------------------------------------------------------------------DATA_STORE[0] = 8'h04;
DATA_STORE[1] = 8'h03;
DATA_STORE[2] = 8'h02;
DATA_STORE[3] = 8'h01;
P_READ_DATA = 32'hffff_ffff; // make sure P_READ_DATA has known initial value
TSK_TX_MEMORY_WRITE_32(DEFAULT_TAG, DEFAULT_TC, 10'd1, BAR_INIT_P_BAR[ii][31:0] , 4'hF,
4'hF, 1'b0);
TSK_TX_CLK_EAT(10);
DEFAULT_TAG = DEFAULT_TAG + 1;
//-----------------------------------------------------------------------// Event : Memory Read 32 bit TLP
//-----------------------------------------------------------------------TSK_TX_MEMORY_READ_32(DEFAULT_TAG, DEFAULT_TC, 10'd1, BAR_INIT_P_BAR[ii][31:0], 4'hF,
4'hF);
TSK_WAIT_FOR_READ_DATA;
if (P_READ_DATA != {DATA_STORE[3], DATA_STORE[2], DATA_STORE[1], DATA_STORE[0] })
begin
$display("[%t] : Test FAILED --- Data Error Mismatch, Write Data %x != Read Data %x",
$realtime,{DATA_STORE[3], DATA_STORE[2], DATA_STORE[1], DATA_STORE[0]}, P_READ_DATA);
end
else
begin
$display("[%t] : Test PASSED --- Write Data: %x successfully received", $realtime,
P_READ_DATA);
end
Expanding the Root Port Model
The Root Port Model was created to work with the PIO design, and for this reason is tailored
to make specific checks and warnings based on the limitations of the PIO design. These
checks and warnings are enabled by default when the Root Port Model is generated in the
Vivado IDE. However, you can disable these limitations so that they do not affect the design.
Because the PIO design was created to support at most one I/O BAR, one Mem64 BAR, and
two Mem32 BARs (one of which must be the EROM space), the Root Port Model by default
makes a check during device configuration that verifies that the core has been configured
to meet this requirement. A violation of this check causes a warning message to be
displayed as well as for the offending BAR to be gracefully disabled in the test bench. This
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check can be disabled by setting the pio_check_design variable to zero in the
pci_exp_usrapp_tx.v file.
Root Port Model TPI Task List
The Root Port Model TPI tasks include these tasks, which are further defined in these tables.
•
Table 6-2: Test Setup Tasks
•
Table 6-3: TLP Tasks
•
Table 6-4: BAR Initialization Tasks
•
Table 6-5: Example PIO Design Tasks
•
Table 6-6: Expectation Tasks
Table 6-2:
Test Setup Tasks
Name
Input
Description
TSK_SYSTEM_INITIALIZATION
None
Waits for transaction interface reset and link-up
between the Root Port Model and the Endpoint DUT.
This task must be invoked prior to the Endpoint core
initialization.
TSK_USR_DATA_SETUP_SEQ
None
Initializes global 4096 byte DATA_STORE array
entries to sequential values from zero to 4095.
TSK_TX_CLK_EAT
clock count
31:30
Waits clock_count transaction interface clocks.
TSK_SIMULATION_TIMEOUT
timeout
31:0
Sets master simulation timeout value in units of
transaction interface clocks. This task should be used
to ensure that all DUT tests complete.
Table 6-3:
TLP Tasks
Name
Input
Description
7:0
11:0
3:0
Waits for transaction interface reset and link-up
between the Root Port Model and the Endpoint
DUT.
This task must be invoked prior to Endpoint core
initialization.
tag_
reg_addr_
first_dw_be_
7:0
11:0
3:0
Sends a Type 1 PCI Express Config Read TLP from
Root Port Model to reg_addr_ of Endpoint DUT
with tag_ and first_dw_be_ inputs.
CplD returned from the Endpoint DUT uses the
contents of global COMPLETE_ID_CFG as the
completion ID.
tag_
reg_addr_
TSK_TX_TYPE0_CONFIGURATION_WRITE
reg_data_
first_dw_be_
7:0
11:0
31:0
3:0
Sends a Type 0 PCI Express Config Write TLP
from Root Port Model to reg_addr_ of Endpoint
DUT with tag_ and first_dw_be_ inputs.
Cpl returned from the Endpoint DUT uses the
contents of global COMPLETE_ID_CFG as the
completion ID.
TSK_TX_TYPE0_CONFIGURATION_READ
TSK_TX_TYPE1_CONFIGURATION_READ
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tag_
reg_addr_
first_dw_be_
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Table 6-3:
TLP Tasks (Cont’d)
Name
Input
Description
tag_
reg_addr_
TSK_TX_TYPE1_CONFIGURATION_WRITE
reg_data_
first_dw_be_
7:0
11:0
31:0
3:0
Sends a Type 1 PCI Express Config Write TLP
from Root Port Model to reg_addr_ of Endpoint
DUT with tag_ and first_dw_be_ inputs.
Cpl returned from the Endpoint DUT uses the
contents of global COMPLETE_ID_CFG as the
completion ID.
TSK_TX_MEMORY_READ_32
tag_
tc_
len_
addr_
last_dw_be_
first_dw_be_
7:0
2:0
9:0
31:0
3:0
3:0
Sends a PCI Express Memory Read TLP from Root
Port to 32-bit memory address addr_ of
Endpoint DUT.
CplD returned from the Endpoint DUT uses the
contents of global COMPLETE_ID_CFG as the
completion ID.
TSK_TX_MEMORY_READ_64
tag_
tc_
len_
addr_
last_dw_be_
first_dw_be_
7:0
2:0
9:0
63:0
3:0
3:0
Sends a PCI Express Memory Read TLP from Root
Port Model to 64-bit memory address addr_ of
Endpoint DUT.
CplD returned from the Endpoint DUT uses the
contents of global COMPLETE_ID_CFG as the
completion ID.
TSK_TX_MEMORY_WRITE_32
tag_
tc_
len_
addr_
last_dw_be_
first_dw_be_
ep_
7:0
2:0
9:0
31:0
3:0
3:0
–
Sends a PCI Express Memory Write TLP from
Root Port Model to 32-bit memory address
addr_ of Endpoint DUT.
CplD returned from the Endpoint DUT uses the
contents of global COMPLETE_ID_CFG as the
completion ID.
The global DATA_STORE byte array is used to
pass write data to task.
TSK_TX_MEMORY_WRITE_64
tag_
tc_
len_
addr_
last_dw_be_
first_dw_be_
ep_
7:0
2:0
9:0
63:0
3:0
3:0
–
Sends a PCI Express Memory Write TLP from
Root Port Model to 64-bit memory address
addr_ of Endpoint DUT.
CplD returned from the Endpoint DUT uses the
contents of global COMPLETE_ID_CFG as the
completion ID.
The global DATA_STORE byte array is used to
pass write data to task.
TSK_TX_COMPLETION
tag_
tc_
len_
comp_status_
7:0
2:0
9:0
2:0
Sends a PCI Express Completion TLP from Root
Port Model to the Endpoint DUT using global
COMPLETE_ID_CFG as the completion ID.
TSK_TX_COMPLETION_DATA
tag_
tc_
len_
byte_count
lower_addr
comp_status
ep_
7:0
2:0
9:0
11:0
6:0
2:0
–
Sends a PCI Express Completion with Data TLP
from Root Port Model to the Endpoint DUT using
global COMPLETE_ID_CFG as the completion ID.
The global DATA_STORE byte array is used to
pass completion data to task.
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Table 6-3:
TLP Tasks (Cont’d)
Name
Input
Description
TSK_TX_MESSAGE
tag_
tc_
len_
data
message_rtg
message_code
7:0
2:0
9:0
63:0
2:0
7:0
Sends a PCI Express Message TLP from Root Port
Model to Endpoint DUT.
Completion returned from the Endpoint DUT
uses the contents of global COMPLETE_ID_CFG
as the completion ID.
TSK_TX_MESSAGE_DATA
tag_
tc_
len_
data
message_rtg
message_code
7:0
2:0
9:0
63:0
2:0
7:0
Sends a PCI Express Message with Data TLP from
Root Port Model to Endpoint DUT.
The global DATA_STORE byte array is used to
pass message data to task.
Completion returned from the Endpoint DUT
uses the contents of global COMPLETE_ID_CFG
as the completion ID.
TSK_TX_IO_READ
tag_
addr_
first_dw_be_
7:0
31:0
3:0
Sends a PCI Express I/O Read TLP from Root Port
Model to I/O address addr_[31:2] of the
Endpoint DUT.
CplD returned from the Endpoint DUT uses the
contents of global COMPLETE_ID_CFG as the
completion ID.
TSK_TX_IO_WRITE
tag_
addr_
first_dw_be_
data
7:0
31:0
3:0
31:0
Sends a PCI Express I/O Write TLP from Root Port
Model to I/O address addr_[31:2] of the
Endpoint DUT.
CplD returned from the Endpoint DUT uses the
contents of global COMPLETE_ID_CFG as the
completion ID.
2:0
31:0
7:0
2:0
Sends a PCI Express one DWORD Memory 32,
Memory 64, or I/O Read TLP from the Root Port
Model to the target address corresponding to
offset byte_offset from BAR bar_index of the
Endpoint DUT. This task sends the appropriate
Read TLP based on how BAR bar_index has been
configured during initialization. This task can
only be called after TSK_BAR_INIT has
successfully completed.
CplD returned from the Endpoint DUT use the
contents of global COMPLETE_ID_CFG as the
completion ID.
TSK_TX_BAR_READ
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bar_index
byte_offset
tag_
tc_
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Table 6-3:
TLP Tasks (Cont’d)
Name
Input
bar_index
byte_offset
tag_
tc_
data_
TSK_TX_BAR_WRITE
TSK_WAIT_FOR_READ_DATA
Table 6-4:
Description
2:0
31:0
7:0
2:0
31:0
None
Sends a PCI Express one DWORD Memory 32,
Memory 64, or I/O Write TLP from the Root Port
to the target address corresponding to offset
byte_offset from BAR bar_index of the Endpoint
DUT.
This task sends the appropriate Write TLP based
on how BAR bar_index has been configured
during initialization. This task can only be called
after TSK_BAR_INIT has successfully completed.
Waits for the next completion with data TLP that
was sent by the Endpoint DUT. On successful
completion, the first DWORD of data from the
CplD is stored in the global P_READ_DATA. This
task should be called immediately following any
of the read tasks in the TPI that request
Completion with Data TLPs to avoid any race
conditions.
By default this task locally times out and
terminates the simulation after 1,000 transaction
interface clocks. The global cpld_to_finish can
be set to zero so that local timeout returns
execution to the calling test and does not result
in simulation timeout. For this case test
programs should check the global cpld_to,
which when set to one indicates that this task
has timed out and that the contents of
P_READ_DATA are invalid.
BAR Initialization Tasks
Name
TSK_BAR_INIT
TSK_BAR_SCAN
Input
Description
None
Performs a standard sequence of Base Address Register initialization
tasks to the Endpoint device using the PCI Express logic. Performs a scan
of the Endpoint PCI BAR range requirements, performs the necessary
memory and I/O space mapping calculations, and finally programs the
Endpoint so that it is ready to be accessed.
On completion, your test program can begin memory and I/O
transactions to the device. This function displays to standard output a
memory and I/O table that details how the Endpoint has been
initialized. This task also initializes global variables within the Root Port
Model that are available for test program usage. This task should only
be called after TSK_SYSTEM_INITIALIZATION.
None
Performs a sequence of PCI Type 0 Configuration Writes and
Configuration Reads using the PCI Express logic to determine the
memory and I/O requirements for the Endpoint.
The task stores this information in the global array
BAR_INIT_P_BAR_RANGE[]. This task should only be called after
TSK_SYSTEM_INITIALIZATION.
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Table 6-4:
BAR Initialization Tasks (Cont’d)
Name
TSK_BUILD_PCIE_MAP
TSK_DISPLAY_PCIE_MAP
Table 6-5:
Input
Description
None
Performs memory and I/O mapping algorithm and allocates Memory
32, Memory 64, and I/O space based on the Endpoint requirements.
This task has been customized to work in conjunction with the
limitations of the PIO design and should only be called after completion
of TSK_BAR_SCAN.
None
Displays the memory mapping information of the Endpoint core PCI
Base Address Registers. For each BAR, the BAR value, the BAR range, and
BAR type is given. This task should only be called after completion of
TSK_BUILD_PCIE_MAP.
Example PIO Design Tasks
Name
TSK_TX_READBACK_CONFIG
TSK_MEM_TEST_DATA_BUS
TSK_MEM_TEST_ADDR_BUS
TSK_MEM_TEST_DEVICE
Input
Description
None
Performs a sequence of PCI Type 0 Configuration Reads
to the Endpoint device Base Address Registers, PCI
Command Register, and PCIe Device Control Register
using the PCI Express logic.
This task should only be called after
TSK_SYSTEM_INITIALIZATION.
bar_index
bar_index
nBytes
bar_index
nBytes
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2:0
Tests whether the PIO design FPGA block RAM data bus
interface is correctly connected by performing a 32-bit
walking ones data test to the I/O or memory address
pointed to by the input bar_index.
For an exhaustive test, this task should be called four
times, once for each block RAM used in the PIO design.
2:0
31:0
Tests whether the PIO design FPGA block RAM address
bus interface is accurately connected by performing a
walking ones address test starting at the I/O or memory
address pointed to by the input bar_index.
For an exhaustive test, this task should be called four
times, once for each block RAM used in the PIO design.
Also, the nBytes input should specify the entire size of
the individual block RAM.
2:0
31:0
Tests the integrity of each bit of the PIO design FPGA
block RAM by performing an increment/decrement test
on all bits starting at the block RAM pointed to by the
input bar_index with the range specified by input
nBytes.
For an exhaustive test, this task should be called four
times, once for each block RAM used in the PIO design.
Also, the nBytes input should specify the entire size of
the individual block RAM.
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Table 6-6:
Expectation Tasks
Name
Input
Output
TSK_EXPECT_CPLD
traffic_class
td
ep
attr
length
completer_id
completer_status
bcm
byte_count
requester_id
tag
address_low
2:0
1:0
9:0
15:0
2:0
11:0
15:0
7:0
6:0
TSK_EXPECT_CPL
traffic_class
td
ep
attr
completer_id
completer_status
bcm
byte_count
requester_id
tag
address_low
2:0
1:0
15:0
2:0
11:0
15:0
7:0
6:0
TSK_EXPECT_MEMRD
traffic_class
td
ep
attr
length
requester_id
tag
last_dw_be
first_dw_be
address
2:0
1:0
9:0
15:0
7:0
3:0
3:0
29:0
TSK_EXPECT_MEMRD64
traffic_class
td
ep
attr
length
requester_id
tag
last_dw_be
first_dw_be
address
2:0
1:0
9:0
15:0
7:0
3:0
3:0
61:0
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Description
Expect
status
Waits for a Completion with
Data TLP that matches
traffic_class, td, ep, attr, length,
and payload.
Returns a 1 on successful
completion; 0 otherwise.
Expect
status
Waits for a Completion without
Data TLP that matches
traffic_class, td, ep, attr, and
length.
Returns a 1 on successful
completion; 0 otherwise.
Expect
status
Waits for a 32-bit Address
Memory Read TLP with
matching header fields.
Returns a 1 on successful
completion; 0 otherwise. This
task can only be used in
conjunction with Bus Master
designs.
Expect
status
Waits for a 64-bit Address
Memory Read TLP with
matching header fields. Returns
a 1 on successful completion; 0
otherwise.
This task can only be used in
conjunction with Bus Master
designs.
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Table 6-6:
Expectation Tasks (Cont’d)
Name
Input
Output
TSK_EXPECT_MEMWR
traffic_class
td
ep
attr
length
requester_id
tag
last_dw_be
first_dw_be
address
2:0
1:0
9:0
15:0
7:0
3:0
3:0
29:0
TSK_EXPECT_MEMWR64
traffic_class
td
ep
attr
length
requester_id
tag
last_dw_be
first_dw_be
address
2:0
1:0
9:0
15:0
7:0
3:0
3:0
61:0
TSK_EXPECT_IOWR
td
ep
requester_id
tag
first_dw_be
address
data
15:0
7:0
3:0
31:0
31:0
Description
Expect
status
Waits for a 32-bit Address
Memory Write TLP with
matching header fields. Returns
a 1 on successful completion; 0
otherwise.
This task can only be used in
conjunction with Bus Master
designs.
Expect
status
Waits for a 64-bit Address
Memory Write TLP with
matching header fields. Returns
a 1 on successful completion; 0
otherwise.
This task can only be used in
conjunction with Bus Master
designs.
Expect
status
Waits for an I/O Write TLP with
matching header fields. Returns
a 1 on successful completion; 0
otherwise.
This task can only be used in
conjunction with Bus Master
designs.
Endpoint Model Test Bench for Root Port
The Endpoint model test bench for the 7 Series FPGAs Integrated Block for PCI Express core
in Root Port configuration is a simple example test bench that connects the Configurator
example design and the PCI Express Endpoint model allowing the two to operate like two
devices in a physical system. Because the Configurator example design consists of logic that
initializes itself and generates and consumes bus traffic, the example test bench only
implements logic to monitor the operation of the system and terminate the simulation.
The Endpoint model test bench consists of:
•
Verilog or VHDL source code for all Endpoint model components
•
PIO slave design
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Figure 5-13, page 282 illustrates the Endpoint model coupled with the Configurator
example design.
Architecture
The Endpoint model consists of these blocks:
•
PCI Express Endpoint (7 Series FPGAs Integrated Block for PCI Express in Endpoint
configuration) model.
•
PIO slave design, consisting of:
°
PIO_RX_ENGINE
°
PIO_TX_ENGINE
°
PIO_EP_MEM
°
PIO_TO_CTRL
The PIO_RX_ENGINE and PIO_TX_ENGINE blocks interface with the ep block for reception
and transmission of TLPs from/to the Root Port Design Under Test (DUT). The Root Port DUT
consists of the core configured as a Root Port and the Configurator Example Design, which
consists of a Configurator block and a PIO Master design, or customer design.
The PIO slave design is described in detail in Programmed Input/Output: Endpoint Example
Design, page 266.
Simulating the Example Design
To simulate the design, see Simulating the Example Design, page 289.
Note: For Cadence IES, the work construct DEFINE WORK WORK must be inserted manually into the
cds.lib file.
Scaled Simulation Timeouts
The simulation model of the core uses scaled down times during link training to allow for
the link to train in a reasonable amount of time during simulation. According to the PCI
Express Specification, rev. 2.1 [Ref 2], there are various timeouts associated with the link
training and status state machine (LTSSM) states. The core scales these timeouts by a factor
of 256 in simulation, except in the Recovery Speed_1 LTSSM state, where the timeouts are
not scaled.
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Chapter 6: Test Benches
Output Logging
The test bench outputs messages, captured in the simulation log, indicating the time at
which these occur:
•
user_reset is deasserted
•
user_lnk_up is asserted
•
cfg_done is asserted by the Configurator
•
pio_test_finished is asserted by the PIO Master
•
Simulation Timeout (if pio_test_finished or pio_test_failed is never asserted)
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Appendix A
Migrating and Upgrading
This appendix contains information about migrating a design from ISE ® Design Suite to the
Vivado® Design Suite, and for upgrading to a more recent version of the IP core. For
customers upgrading in the Vivado Design Suite, important details (where applicable)
about any port changes and other impact to user logic are included.
Migrating to the Vivado Design Suite
This section covers:
•
Migration to 7 Series Devices
•
TRN to AXI Migration Considerations
For information on migrating to the Vivado Design Suite, see ISE to Vivado Design Suite
Migration Methodology Guide (UG911)[Ref 18].
Migration to 7 Series Devices
For migrating to the 7 Series FPGAs Integrated Block for PCI Express® from the Virtex®-6
FPGA Integrated Block for PCI Express, the list in this section describes the differences in
behaviors and options between the 7 Series FPGAs Integrated Block for PCI Express core
and the Virtex-6 FPGA Integrated Block for PCI Express core, version v2.x with the
AXI4-Stream interface.
Core Capability Differences
•
8-Lane, 5.0 Gb/s (Gen2) Speed Operation for Root Port Configuration: The 7 Series
FPGAs Integrated Block for PCI Express also supports the 5.0 Gb/s speed operation for
the 8-lane Root Port Configuration.
•
128-bit Interface: The 7 Series Integrated Block for PCIe supports the 128-bit interface
for the 8-lane, 2.5 Gb/s configuration and 4-lane, 5.0 Gb/s configuration.
Configuration Interface
Table A-1 lists the Configuration interface signals whose names were changed.
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Appendix A: Migrating and Upgrading
Table A-1:
Configuration Interface Changes
Signal Name in
Virtex-6 FPGA Integrated
Block for PCI Express
Signal Name in
7 Series FPGAs Integrated
Block for PCI Express
cfg_do
cfg_mgmt_do
cfg_rd_wr_done
cfg_mgmt_rd_wr_done
cfg_di
cfg_mgmt_di
Configuration DWORD Address
cfg_dwaddr
cfg_mgmt_dwaddr
Configuration Byte Enable
cfg_byte_en
cfg_mgmt_byte_en
Configuration Write Enable
cfg_wr_en
cfg_mgmt_wr_en
Configuration Read Enable
cfg_rd_en
cfg_mgmt_rd_en
Name
Configuration Data Out
Configuration Read Write Done
Configuration Data In
Table A-2 lists the new Configuration interface signals. See Designing with Configuration
Space Registers and Configuration Interface in Chapter 3 for detailed information.
Table A-2:
New Configuration Interface Signals
Signal
cfg_mgmt_wr_rw1c_as_rw
cfg_mgmt_wr_readonly
Description
New Configuration Write signals in the core.
cfg_pm_halt_aspm_l0s
cfg_pm_halt_aspm_l1 (1)
cfg_pm_force_state[1:0]
New Power Management signals in the core.
cfg_pm_force_state_en
cfg_err_aer_headerlog[127:0]
cfg_err_aer_headerlog_set
cfg_aer_interrupt_msgnum[4:0]
New AER Interface signals.
cfg_aer_ecrc_gen_en
cfg_aer_ecrc_check_en
cfg_pciecap_interrupt_msgnum[4:0]
cfg_interrupt_stat
cfg_vc_tcvc_map[6:0]
New Interrupt interface signals
New TC/VC Map signal
Notes:
1. ASPM L1 is unsupported in the 7 Series Integrated Block for PCIe.
Error Reporting Signals
The 7 Series FPGAs Integrated Block for PCI Express core supports the additional error
reporting signals listed below. See Designing with Configuration Space Registers and
Configuration Interface in Chapter 3 for detailed information.
•
cfg_err_poisoned
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•
cfg_err_malformed
•
cfg_err_acs
•
cfg_err_atomic_egress_blocked
•
cfg_err_mc_blocked
•
cfg_err_internal_uncor
•
cfg_err_internal_cor
•
cfg_err_norecovery
ID Initial Values
The ID initial values (Vendor ID, Device ID, Revision ID, Subsystem Vendor ID, and Subsystem
ID) have changed from attributes on Virtex-6 FPGA Integrated Block for PCI Express to input
ports on the 7 Series FPGAs Integrated Block for PCI Express. These values are set in the
Vivado® Integrated Design Environment (IDE), and are used to drive these ports in the
7 Series FPGAs Integrated Block for PCI Express. These ports are not available at the core
boundary of the wrapper, but are available within the top-level wrapper of the 7 Series
FPGAs Integrated Block for PCI Express. Table A-3 lists the ID values and the corresponding
ports.
Table A-3:
ID Values and Corresponding Ports
ID Value
Input Port
Vendor ID
cfg_vend_id[15:0]
Device ID
cfg_dev_id[15:0]
Revision ID
cfg_rev_id[7:0]
Subsystem Vendor ID
cfg_subsys_vend_id[15:0]
Subsystem ID
cfg_subsys_id[15:0]
Physical Layer Interface
Table A-4 and Table A-5 list the changes in the Physical Layer interface in the 7 Series FPGAs
Integrated Block for PCI Express.
Table A-4:
Physical Layer Signal Name Changes
Signal Name in
Virtex-6 FPGA Integrated Block for PCI Express
Signal Name in
7 Series FPGAs Integrated Block for PCI Express
pl_link_gen2_capable
pl_link_gen2_cap
pl_link_upcfg_capable
pl_link_upcfg_cap
pl_sel_link_rate
pl_sel_lnk_rate
pl_sel_link_width
pl_sel_lnk_width
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Table A-5:
New Physical Layer Signals
Signal
Description
pl_directed_change_done
Indicates the Directed change is done.
pl_phy_lnk_up
Indicates Physical Layer Link Up Status
pl_rx_pm_state
Indicates RX Power Management State
pl_tx_pm_state
Indicates TX Power Management State
Dynamic Reconfiguration Port Interface
Some signals names on the Dynamic Reconfiguration Port Interface have changed in the
7 Series FPGAs Integrated Block for PCI Express. Table A-6 shows the signals that have
changed on this interface.
Table A-6:
Dynamic Reconfiguration Port Name Changes
Port Name in
Virtex-6 FPGA Integrated Block for PCI Express
Port Name in
7 Series FPGAs Integrated Block for PCI Express
pcie_drp_den
pcie_drp_en
pcie_drp_dwe
pcie_drp_we
pcie_drp_daddr
pcie_drp_addr
pcie_drp_drdy
pcie_drp_rdy
TRN to AXI Migration Considerations
This section describes the differences in signal naming and behavior when migrating to the
7 Series FPGAs Integrated Block for PCI Express core from the Virtex-6 FPGA Integrated
Block for PCI Express core, v1.x, with TRN interface.
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High-Level Summary
The 7 Series FPGAs Integrated Block for PCI Express updates the main user interface from
TRN to the standard AXI4-Stream signal naming and behavior. In addition, all control signals
that were active-Low have been changed to active-High. This list summarizes the main
changes to the core:
•
Signal name changes
•
Datapath DWORD ordering
•
All control signals are active-High
•
Start-of-frame (SOF) signaling is implied
•
Remainder signals are replaced with Strobe signals
Step-by-Step Migration Guide
This section describes the steps that a user should take to migrate an existing user
application based on TRN to the AXI4-Stream interface.
1. For each signal in Table A-7 labeled “Name change only”, connect the appropriate user
application signal to the newly named core signal.
2. For each signal in Table A-7 labeled “Name change; Polarity”, add an inverter and
connect the appropriate user application signal to the newly named core signal.
3. Swap the DWORD ordering on the datapath signals as described in Datapath DWORD
Ordering.
4. Leave disconnected the user application signal originally connected to trn_tsof_n.
5. Recreate trn_rsof_n as described in the Start-Of-Frame Signaling section and connect
to the user application as was originally connected.
6. Make the necessary changes as described in the Remainder/Strobe Signaling section.
7. If using the trn_rsrc_dsc_n signal in the original design, make the changes as
described in Packet Transfer Discontinue on Receive section, otherwise leave
disconnected.
8. Make the changes as described in the Packet Re-ordering on Receive section.
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Signal Changes
Table A-7 details the main differences in signaling between TRN local-link to AXI4-Stream.
Table A-7:
Interface Changes
TRN Name
AXI4-Stream Name
Difference
sys_reset_n
sys_rst_n
No change
trn_clk
user_clk_out
Name change
trn_reset_n
user_reset_out
Name change; Polarity
trn_lnk_up_n
user_lnk_up
Name change; Polarity
trn_fc_ph[7:0]
fc_ph[7:0]
Name change only
trn_fc_pd[11:0]
fc_pd[11:0]
Name change only
trn_fc_nph[7:0]
fc_nph[7:0]
Name change only
trn_fc_npd[11:0]
fc_npd[11:0]
Name change only
trn_fc_cplh[7:0]
fc_cplh[7:0]
Name change only
trn_fc_cpld[11:0]
fc_cpld[11:0]
Name change only
trn_fc_sel[2:0]
fc_sel[2:0]
Name change only
Common Interface
Transmit Interface
trn_tsof_n
No equivalent for 32- and 64-bit version (see text)
trn_teof_n
s_axis_tx_tlast
Name change; Polarity
trn_td[W-1:0]
(W = 32, 64, or 128)
s_axis_tx_tdata[W-1:0]
Name change; DWORD Ordering (see text)
trn_trem_n
(64-bit interface)
s_axis_tx_tkeep[7:0]
Name change; Functional differences (see text)
trn_trem_n[1:0]
(128-bit interface)
s_axis_tx_tkeep[15:0]
Name change; Functional differences (see text)
trn_tsrc_rdy_n
s_axis_tx_tvalid
Name change; Polarity
trn_tdst_rdy_n
s_axis_tx_tready
Name change; Polarity
trn_tsrc_dsc_n
s_axis_tx_tuser[3]
Name change; Polarity
trn_tbuf_av[5:0]
tx_buf_av[5:0]
Name Change
trn_terr_drop_n
tx_err_drop
Name change; Polarity
trn_tstr_n
s_axis_tx_tuser[2]
Name change; Polarity
trn_tcfg_req_n
tx_cfg_req
Name change; Polarity
trn_tcfg_gnt_n
tx_cfg_gnt
Name change; Polarity
trn_terrfwd_n
s_axis_tx_tuser[1]
Name change; Polarity
Receive Interface
trn_rsof_n
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Table A-7:
Interface Changes (Cont’d)
TRN Name
AXI4-Stream Name
Difference
trn_reof_n
m_axis_rx_tlast (64b)
is_eof[4] (128b)
Name change; Polarity
trn_rd[W-1:0]
(W = 32, 64, or 128)
m_axis_rx_tdata[W-1:0]
Name change; DWORD Ordering
trn_rrem_n
(64-bit interface)
m_axis_rx_tkeep
Name change; Functional differences (see text)
trn_rrem_n[1:0]
(128-bit interface)
m_axis_rx_tuser[14:10],
m_axis_rx_tuser[21:17]
Name change; Functional differences (see text)
trn_rerrfwd_n
m_axis_rx_tuser[1]
Name change; Polarity
trn_rsrc_rdy_n
m_axis_rx_tvalid
Name change; Polarity
trn_rdst_rdy_n
m_axis_rx_tready
Name change; Polarity
trn_rsrc_dsc_n
No equivalent
trn_rnp_ok_n
rx_np_ok
Name change; Polarity; Extra delay (see text)
trn_rbar_hit_n[7:0]
m_axis_rx_tuser[9:2]
Name change; Polarity
cfg_rd_wr_done_n
cfg_mgmt_rd_wr_done
Name change; Polarity
cfg_byte_en_n[3:0]
cfg_mgmt_byte_en[3:0]
Name change; Polarity
cfg_wr_en_n
cfg_mgmt_wr_en
Name change; Polarity
cfg_rd_en_n
cfg_mgmt_rd_en
Name change; Polarity
cfg_pcie_link_state_n[2:0]
cfg_pcie_link_state[2:0]
Name change only
cfg_trn_pending_n
cfg_trn_pending
Name change; Polarity
cfg_to_turnoff_n
cfg_to_turnoff
Name change; Polarity
cfg_turnoff_ok_n
cfg_turnoff_ok
Name change; Polarity
cfg_pm_wake_n
cfg_pm_wake
Name change; Polarity
cfg_wr_rw1c_as_rw_n
cfg_mgmt_wr_rw1c_as_rw
Name change; Polarity
cfg_interrupt_n
cfg_interrupt
Name change; Polarity
cfg_interrupt_rdy_n
cfg_interrupt_rdy
Name change; Polarity
cfg_interrupt_assert_n
cfg_interrupt_assert
Name change; Polarity
cfg_err_ecrc_n
cfg_err_ecrc
Name change; Polarity
cfg_err_ur_n
cfg_err_ur
Name change; Polarity
cfg_err_cpl_timeout_n
cfg_err_cpl_timeout
Name change; Polarity
cfg_err_cpl_unexpect_n
cfg_err_cpl_unexpect
Name change; Polarity
cfg_err_cpl_abort_n
cfg_err_cpl_abort
Name change; Polarity
cfg_err_posted_n
cfg_err_posted
Name change; Polarity
cfg_err_cor_n
cfg_err_cor
Name change; Polarity
Configuration Interface
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Table A-7:
Interface Changes (Cont’d)
TRN Name
AXI4-Stream Name
Difference
cfg_err_cpl_rdy_n
cfg_err_cpl_rdy
Name change; Polarity
cfg_err_locked_n
cfg_err_locked
Name change; Polarity
Datapath DWORD Ordering
The AXI4-Stream interface swaps the DWORD locations but preserves byte ordering within
an individual DWORD as compared to the TRN interface. This change only affects the 64-bit
and 128-bit versions of the core. Figure A-1 and Figure A-2 illustrate the DWORD swap
ordering from TRN to AXI4-Stream for both 64-bit and 128-bit versions.
X-Ref Target - Figure A-1
trn_td[63:0]
trn_rd[63:0]
DW0
DW1
s_axis_tx_tdata[63:0]
m_axis_rx_rdata[63:0]
DW1
DW0
Figure A-1:
TRN vs. AXI DWORD Ordering on Data Bus (64-Bit)
X-Ref Target - Figure A-2
trn_td[127:0]
trn_rd[127:0]
DW0
DW1
DW2
DW3
s_axis_tx_tdata[127:0]
m_axis_rx_rdata[127:0]
DW3
DW2
DW1
DW0
Figure A-2:
TRN vs. AXI DWORD Ordering on Data Bus (128-Bit)
For migrating existing 64-bit and 128-bit TRN-based designs, you should swap DWORD
locations for the s_axis_tx_tdata[W-1:0] and s_axis_rx_rdata[W-1:0] buses as
they enter and exit the core.
For example, existing user application pseudo code:
usr_trn_rd[127:0] = trn_rd[127:0];
should be modified to:
usr_trn_rd[127:96] = s_axis_rx_rdata[31:0]
usr_trn_rd[95:64] = s_axis_rx_rdata[63:32]
usr_trn_rd[63:32] = s_axis_rx_rdata[95:64]
usr_trn_rd[31:0] = s_axis_rx_rdata[127:96]
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Start-Of-Frame Signaling
AXI4-Stream does not have equivalent signals for start-of-frame (trn_tsof_n and
trn_rsof_n) in the 32-bit and 64-bit versions. On the transmit side, existing TRN designs
can just leave the trn_tsof_n connection unconnected. On the receive side, existing TRN
designs can recreate trn_rsof_n using simple logic, if necessary.
32- and 64-Bit Interfaces
First, create a sequential (clocked) signal called in_packet_reg. A combinatorial logic
function using existing signals from the core can then be used to recreate trn_rsof_n as
illustrated in this pseudo code:
For every clock cycle (user_clk_out) do {
if(reset)
in_packet_reg = 0
else if (m_axis_rx_tvalid and m_axis_rx_tready)
in_packet_reg = !m_axis_rx_tlast
}
trn_rsof_n = !(m_axis_rx_tvalid & !in_packet_reg)
128-Bit Interface
The 128-bit interface provides an SOF signal. You can invert (rx_is_sof[4])
m_axis_rx_tuser[14] to recreate trn_rsof_n.
Remainder/Strobe Signaling
This section covers the changes to the remainder signals trn_trem_n[1:0] and
trn_rrem_n[1:0].
The AXI4-Stream interface uses strobe signaling (byte enables) in place of remainder
signaling. There are three key differences between the strobe signals and the remainder
signals as detailed in Table A-8. There are also some differences between the 64-bit version
and 128-bit version of the core. The 128-bit RX version replaces trn_rrem[1:0] with
(rx_is_sof[4:0]) m_axis_rx_tuser[14:10] and (rx_is_eof[4:0])
m_axis_rx_tuser[21:17], instead of a strobe signal. For simplicity, this section treats
64-bit and 128-bit transmit and receive operations separately.
Table A-8:
Remainder Signal Differences
TRN Remainders
64-bit: trn_trem_n, trn_rrem_n
128-bit: trn_trem_n[1:0], trn_rrem_n[1:0]
AXI4-Stream Strobes
64-bit: s_axis_tx_tkeep[7:0], m_axis_rx_tkeep[7:0]
128-bit: s_axis_tx_tkeep[15:0], rx_is_sof[4:0],
rx_is_eof[4:0]
Active-Low
Active-High
Acts on DWORDs
Acts on Bytes
Only valid on end-of-frame (EOF) cycles
Valid for every clock cycle that tvalid and tready are asserted
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64-Bit Transmit
Existing TRN designs can do a simple conversion from the single trn_trem signal to
s_axis_tx_tkeep[7:0]. Assuming you currently named the signal user_trn_trem
that drives the trn_trem input, the listed pseudo code illustrates the conversion to
s_axis_tx_tkeep[7:0]. You must drive s_axis_tx_tkeep[7:0] every clock cycle
that tvalid is asserted.
if s_axis_tx_tlast == 1
//in a packet at EOF
s_axis_tx_tkeep[7:0] = user_trn_trem_n ? 0Fh : FFh
else
//in a packet but not EOF, or not in a packet
s_axis_tx_tkeep = FFh
64-Bit Receive
Existing TRN designs can do a simple conversion on m_axis_rx_tkeep[7:0] to recreate
the trn_rrem signal using combinatorial logic. The listed pseudo code illustrates the
conversion.
if (C_DATA_WIDTH == 64)
begin
assign trn_rrem = m_axis_rx_tlast ? (m_axis_rx_tkeep == 8'hFF) ? 1'b1 : 1'b0: 1'b1;
end
128-Bit Transmit
Existing TRN designs can do a simple conversion from the single trn_trem[1:0] signal to
s_axis_tx_tkeep[15:0]. Assuming you currently named the signal
user_trn_trem[1:0] that drives the trn_trem[1:0] input, the listed pseudo code
illustrates the conversion to s_axis_tx_tkeep[15:0]. You must drive
s_axis_tx_tkeep[15:0] every clock cycle.
if s_axis_tx_tlast == 1
//in a packet at EOF
if
user_trn_trem_n[1:0]==00b
s_axis_tx_tkeep[15:0] = FFFFh
else if user_trn_trem_n[1:0] = 01b
s_axis_tx_tkeep[15:0] = 0FFFh
else if user_trn_trem_n[1:0] = 10b
s_axis_tx_tkeep[15:0] = 00FFh
else if user_trn_trem_n[1:0] = 11b
s_axis_tx_tkeep[15:0] = 000Fh
else
//in a packet but not EOF, or not in a packet
s_axis_tx_tkeep =FF FFh
128-Bit Receive
The 128-bit receive remainder signal trn_rrem[1:0] does not have an equivalent strobe
signal for AXI4-Stream. Instead, (is_sof[4:0]) m_axis_rx_tuser[14:10] and
(is_eof[4:0]) m_axis_rx_tuser[21:17] are used. Existing TRN designs can do a
conversion on the rx_is_sof and rx_is_eof signals to recreate the trn_rrem[1:0]
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signal using combinatorial logic. The listed pseudo code illustrates the conversion. This
pseudo code assumes that you swapped the DWORD locations from the AXI4-Stream
interface (see the usr_trn_rd[127:0] signal pseudo code).
trn_rrem[1] = ( (rx_is_sof[4] && rx_is_eof[4] && rx_is_eof[3]) || (!rx_is_sof[4] &&
rx_is_eof[4] && rx_is_eof[3]) || (rx_is_sof[4] && !rx_is_eof[4] && !rx_is_sof[3]) )
trn_rrem_n[0] = !rx_is_eof[2]
Note: 128-bit interface does NOT use m_axis_rx_tlast signal at all (tied Low), but rather it uses
m_axis_rx_tuser signals.
Packet Transfer Discontinue on Receive
When the trn_rsrc_dsc_n signal in the TRN interface is asserted, it indicates that a
received packet has been discontinued. The AXI4-Stream interface has no equivalent signal.
On both the TRN and AXI4-Stream cores, however, a packet is only discontinued on the
receive interface if link connectivity is lost. Therefore, you can monitor the user_lnk_up
signal to determine a receive packet discontinue condition.
On the TRN interface, the packet transmission on the data interface (trn_rd) stops
immediately following assertion of trn_rsrc_dsc_n, and trn_reof_n might never be
asserted. On the AXI4-Stream interface, the packet is padded out to the proper length of the
transaction layer packet (TLP), and m_axis_rx_tlast is asserted even though the data is
corrupted. Figure A-3 and Figure A-4 show the TRN and AXI4-Stream signaling for packet
discontinue. To recreate the trn_rsrc_dsc_n signal, you can invert and add one clock
cycle delay to user_lnk_up.
X-Ref Target - Figure A-3
trn_clk
trn_lnk_up_n
trn_rd[127:0]
trn_sof_n
trn_eof_n
trn_rsrc_rdy_n
trn_rdst_rdy_n
trn_rrem_n[1]
trn_rrem_n[0]
trn_rsrc_dsc_n
Figure A-3:
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X-Ref Target - Figure A-4
user_clk_out
user_lnk_up
m_axis_rx_tdata[127:0]
D0H2H1H0
D4D3D2D1
D8D7D6D5
PAD
PAD
original TLP data was lost
m_axis_rx_tready
m_axis_rx_tvalid
(rx_is_sof[4:0])m_axis_rx_tuser[14:10]
10000b
00000b
(rx_is_eof[4:0])m_axis_rx_tuser[21:17]
Figure A-4:
00000b
11111b
Receive Discontinue on the AXI4-Stream Interface
Packet Re-ordering on Receive
The TRN interface uses the trn_rnp_ok_n signal to reorder TLP traffic on the receive
interface. The AXI4-Stream interface has an equivalent signal, rx_np_ok. You need to
account for two differences in the AXI4-Stream interface as shown in Table A-9. You must
account for these differences in your custom logic. If the user application does not use
packet re-ordering, you can tie rx_np_ok to 1b.
Table A-9:
AXI4-Stream Interface Differences
TRN
trn_rnp_ok_n
AXI4-Stream
rx_np_ok
Active-Low
Active-High
Deassert at least one clock cycle before
trn_reof_n of the next-to-last Non-Posted TLP
that the user can accept
Deassert at least one clock cycle before
is_eof[4] of the second-to-last Non-Posted TLP
that the user can accept
System Reset
The system reset is usually provided by PERST#, which is an active-Low signal.
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Upgrading in the Vivado Design Suite
This section provides information about any changes to the user logic or port designations
that take place when you upgrade to a more current version of this IP core in the Vivado
Design Suite.
Parameter Changes
There are no parameter changes in the current version of the core.
Port Changes
The port listed in Table A-10 is available when the Additional Transceiver Control and
Status Ports option is selected.
Table A-10:
Additional Transceiver Control and Status Port
Name
Direction
Width
pipe_txinhibit
I
[(LINK_CAP_MAX_LINK_WIDTH -1) : 0]
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Appendix B
Debugging
This appendix provides information on resources available on the Xilinx® Support website,
and debugging tools.
Finding Help on Xilinx.com
To help in the design and debug process when using the 7 series FPGA, the Xilinx Support
webpage (www.xilinx.com/support) contains key resources such as product documentation,
release notes, answer records, information about known issues, and links for obtaining
further product support.
Documentation
This Product Guide is the main document associated with the 7 Series Integrated Block for
PCIe. This guide along with documentation related to all products that aid in the design
process can be found on the Xilinx Support webpage (www.xilinx.com/support) or by using
the Xilinx Documentation Navigator.
You can download the Xilinx Documentation Navigator from the Design Tools tab on the
Downloads page (www.xilinx.com/download). For more information about this tool and the
features available, see the online help after installation.
Solution Centers
See the Xilinx Solution Centers for support on devices, software tools, and intellectual
property at all stages of the design cycle. Topics include design assistance, advisories, and
troubleshooting tips.
The PCI Express Solution Center is located at Xilinx Solution Center for PCI Express.
Extensive debugging collateral is available in AR: 56802.
Answer Records
Answer Records include information about commonly encountered problems, helpful
information on how to resolve these problems, and any known issues with a Xilinx product.
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Answer Records are created and maintained daily ensuring that you have access to the most
accurate information available.
Answer Records for this core can be located by using the Search Support box on the main
Xilinx support web page. To maximize your search results, use proper keywords such as
•
Product name
•
Tool messages
•
Summary of the issue encountered
A filter search is available after results are returned to further target the results.
Master Answer Record for the 7 Series Integrated Block for PCIe
AR: 54643
Contacting Xilinx Technical Support
Xilinx provides technical support at www.xilinx.com/support for this LogiCORE™ IP product
when used as described in the product documentation. Xilinx cannot guarantee timing,
functionality, or support of product if implemented in devices that are not defined in the
documentation, if customized beyond that allowed in the product documentation, or if
changes are made to any section of the design labeled DO NOT MODIFY.
To contact Technical Support:
1. Navigate to www.xilinx.com/support.
2. Open a WebCase by selecting the WebCase link located under Support Quick Links.
When opening a WebCase, include:
•
Target FPGA including package and speed grade
•
All applicable Xilinx Design Tools, and simulator software versions
•
Additional files might be required based on the specific issue. See the relevant sections
in this debug guide for further information on specific files to include with the
WebCase.
Note: Access to WebCase is not available in all cases. Log in to the WebCase tool to see your specific
support options.
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Appendix B: Debugging
Debug Tools
There are many tools available to debug PCI Express design issues. This section indicates
which tools are useful for debugging the various situations encountered.
Vivado Design Suite Debug Feature
The Vivado® Design Suite debug feature inserts logic analyzer and virtual I/O cores directly
into your design. The debug feature also allows you to set trigger conditions to capture
application and integrated block port signals in hardware. Captured signals can then be
analyzed. This feature in the Vivado IDE is used for logic debugging and validation of a
design running in Xilinx devices.
The Vivado logic analyzer is used to interact with the logic debug LogiCORE IP cores,
including:
•
ILA 2.0 (and later versions)
•
VIO 2.0 (and later versions)
See Vivado Design Suite User Guide: Programming and Debugging (UG908) [Ref 17].
Reference Boards
Various Xilinx development boards support the 7 Series Integrated Block for PCIe. These
boards can be used to prototype designs and establish that the core can communicate with
the system.
•
7 series evaluation boards
°
KC705
°
KC724
°
VC707
°
AC701
Link Analyzers
Third-party link analyzers show link traffic in a graphical or text format. Lecroy, Agilent, and
Vmetro are companies that make common analyzers available today. These tools greatly
assist in debugging link issues and allow you to capture data which Xilinx support
representatives can view to assist in interpreting link behavior.
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Appendix B: Debugging
Third-Party Tools
This section describes third-party software tools that can be useful in debugging.
LSPCI (Linux)
LSPCI is available on Linux platforms and allows you to view the PCI Express device
configuration space. LSPCI is usually found in the /sbin directory. LSPCI displays a list of
devices on the PCI buses in the system. See the LSPCI manual for all command options.
Some useful commands for debugging include:
•
lspci -x -d [<vendor>]:[<device>]
This displays the first 64 bytes of configuration space in hexadecimal form for the device
with vendor and device ID specified (omit the -d option to display information for all
devices). The default Vendor ID for Xilinx cores is 10EE. Here is a sample of a read of the
configuration space of a Xilinx device:
> lspci -x -d 10EE:7028
81:00.0 Memory controller: Xilinx
00: ee 10 28 70 07 00 10 00 00 00
10: 00 00 80 fa 00 00 00 00 00 00
20: 00 00 00 00 00 00 00 00 00 00
30: 00 00 00 00 40 00 00 00 00 00
Corporation: Unknown device 7028
80 05 10 00 00 00
00 00 00 00 00 00
00 00 ee 10 6f 50
00 00 05 01 00 00
Included in this section of the configuration space are the Device ID, Vendor ID, Class
Code, Status and Command, and Base Address Registers.
•
lspci -xxxx -d [<vendor>]:[<device>]
This displays the extended configuration space of the device. It can be useful to read the
extended configuration space on the root and look for the Advanced Error Reporting
(AER) registers. These registers provide more information on why the device has flagged
an error (for example, it might show that a correctable error was issued because of a
replay timer timeout).
•
lspci -k
Shows kernel drivers handling each device and kernel modules capable of handling it
(works with kernel 2.6 or later).
PCItree (Windows)
PCItree can be downloaded at www.pcitree.de and allows the user to view the PCI Express
device configuration space and perform one DWORD memory writes and reads to the
aperture.
The configuration space is displayed by default in the lower right corner when the device is
selected, as shown in Figure B-1.
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Appendix B: Debugging
X-Ref Target - Figure B-1
Figure B-1:
PCItree with Read of Configuration Space
PCI-SIG Software Suites
PCI-SIG® software suites such as PCIE-CV can be used to test compliance with the
specification. This software can be downloaded at www.pcisig.com.
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Appendix B: Debugging
Simulation Debug
The simulation debug flow for QuestaSim is illustrated in Figure B-2.
Note: Endpoints that are shaded gray in Figure B-2 indicate that further explanation is provided in
this section.
X-Ref Target - Figure B-2
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Figure B-2:
7 Series Integrated Block for PCIe v3.1
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;
QuestaSim Debug Flow Diagram
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Appendix B: Debugging
PIO Simulator Expected Output
The PIO design simulation should give the output as follows:
#
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#
Running test {pio_writeReadBack_test0}......
[
0] : System Reset Asserted...
[
4995000] : System Reset De-asserted...
[
48743324] : Transaction Reset Is De-asserted...
[
50471408] : Transaction Link Is Up...
[
50535337] : TSK_PARSE_FRAME on Transmit
[
53799296] : TSK_PARSE_FRAME on Receive
[
58535316] :
Check Max Link Speed = 2.5GT/s - PASSED
[
58535316] : Check Negotiated Link Width = 01x - PASSED
[
58583267] : TSK_PARSE_FRAME on Transmit
[
60967220] : TSK_PARSE_FRAME on Receive
[
66583220] :
Check Device/Vendor ID - PASSED
[
66631220] : TSK_PARSE_FRAME on Transmit
[
69031328] : TSK_PARSE_FRAME on Receive
[
74631328] :
Check CMPS ID - PASSED
[
74631328] : SYSTEM CHECK PASSED
[
74631328] : Inspecting Core Configuration Space...
[
74679316] : TSK_PARSE_FRAME on Transmit
[
76327322] : TSK_PARSE_FRAME on Transmit
[
77031308] : TSK_PARSE_FRAME on Receive
[
78727272] : TSK_PARSE_FRAME on Receive
[
84375277] : TSK_PARSE_FRAME on Transmit
[
86023267] : TSK_PARSE_FRAME on Transmit
[
86727220] : TSK_PARSE_FRAME on Receive
[
88423220] : TSK_PARSE_FRAME on Receive
[
94071220] : TSK_PARSE_FRAME on Transmit
[
95719220] : TSK_PARSE_FRAME on Transmit
[
96423288] : TSK_PARSE_FRAME on Receive
[
98119322] : TSK_PARSE_FRAME on Receive
[
103767322] : TSK_PARSE_FRAME on Transmit
[
105415337] : TSK_PARSE_FRAME on Transmit
[
106119316] : TSK_PARSE_FRAME on Receive
[
107815316] : TSK_PARSE_FRAME on Receive
[
113463267] : TSK_PARSE_FRAME on Transmit
[
115111308] : TSK_PARSE_FRAME on Transmit
[
115815207] : TSK_PARSE_FRAME on Receive
[
117511220] : TSK_PARSE_FRAME on Receive
[
123159220] : TSK_PARSE_FRAME on Transmit
[
124807220] : TSK_PARSE_FRAME on Transmit
[
125511308] : TSK_PARSE_FRAME on Receive
[
127207296] : TSK_PARSE_FRAME on Receive
[
132855337] : TSK_PARSE_FRAME on Transmit
[
134503288] : TSK_PARSE_FRAME on Transmit
[
135207316] : TSK_PARSE_FRAME on Receive
[
136903316] : TSK_PARSE_FRAME on Receive
[
142503316] PCI EXPRESS BAR MEMORY/IO MAPPING PROCESS BEGUN...
BAR 0: VALUE = 00000000 RANGE = fff00000 TYPE = MEM32 MAPPED
BAR 1: VALUE = 00000000 RANGE = 00000000 TYPE =
DISABLED
BAR 2: VALUE = 00000000 RANGE = 00000000 TYPE =
DISABLED
BAR 3: VALUE = 00000000 RANGE = 00000000 TYPE =
DISABLED
BAR 4: VALUE = 00000000 RANGE = 00000000 TYPE =
DISABLED
BAR 5: VALUE = 00000000 RANGE = 00000000 TYPE =
DISABLED
EROM : VALUE = 00000000 RANGE = 00000000 TYPE =
DISABLED
[
142503316] : Setting Core Configuration Space...
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Appendix B: Debugging
#
#
#
#
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#
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[
142551308] : TSK_PARSE_FRAME on Transmit
[
144199316] : TSK_PARSE_FRAME on Transmit
[
144903193] : TSK_PARSE_FRAME on Receive
[
145847316] : TSK_PARSE_FRAME on Transmit
[
146567204] : TSK_PARSE_FRAME on Receive
[
147495316] : TSK_PARSE_FRAME on Transmit
[
148199270] : TSK_PARSE_FRAME on Receive
[
149143316] : TSK_PARSE_FRAME on Transmit
[
149863267] : TSK_PARSE_FRAME on Receive
[
150791328] : TSK_PARSE_FRAME on Transmit
[
151495316] : TSK_PARSE_FRAME on Receive
[
152439322] : TSK_PARSE_FRAME on Transmit
[
153159316] : TSK_PARSE_FRAME on Receive
[
154087296] : TSK_PARSE_FRAME on Transmit
[
154791316] : TSK_PARSE_FRAME on Receive
[
155735315] : TSK_PARSE_FRAME on Transmit
[
156455316] : TSK_PARSE_FRAME on Receive
[
158087322] : TSK_PARSE_FRAME on Receive
[
171735277] : Transmitting TLPs to Memory 32 Space BAR 0
[
171783193] : TSK_PARSE_FRAME on Transmit
[
171991308] : TSK_PARSE_FRAME on Transmit
[
174247296] : TSK_PARSE_FRAME on Receive
[
179943316] : Test PASSED --- Write Data: 01020304 successfully received
[
180103267] : Finished transmission of PCI-Express TLPs
** Note: $finish
: ../tests/sample_tests1.v(317)
Time: 180103267 ps Iteration: 6 Instance: /board/RP/tx_usrapp
Compiling Simulation Libraries
Use the compile_simlib command to compile simulation libraries. This tool is delivered
as part of the Xilinx software. For more information, see Vivado Design Suite User Guide:
Logic Simulation (UG900) [Ref 16] and Vivado Design Suite Tcl Command Reference Guide
(UG835) [Ref 20].
compile_simlib produces a modelsim.ini file containing the library mappings. In
QuestaSim, type vmap at the prompt to see the current library mappings. The mappings can
be updated in the ini file, or to map a library at the QuestaSim prompt, type:
vmap [<logical_name>] [<path>]
For example:
Vmap unisims_ver C:\my_unisim_lib
Next Step
If the debug suggestions listed previously do not resolve the issue, open a support case or
visit the Xilinx User Community forums to have the appropriate Xilinx expert assist with the
issue.
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Appendix B: Debugging
To create a technical support case in WebCase, see the Xilinx website at:
www.xilinx.com/support/clearexpress/websupport.htm
Items to include when opening a case:
°
Detailed description of the issue and results of the steps listed above.
°
Attach a VCD or WLF dump of the simulation.
To discuss possible solutions, use the Xilinx User Community:
forums.xilinx.com/xlnx/
Hardware Debug
Hardware issues can range from device recognition issues to problems seen after hours of
testing. This section provides debug flow diagrams for some of the most common issues.
Endpoints that are shaded gray indicate that more information can be found in sections
after Figure B-3.
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Appendix B: Debugging
X-Ref Target - Figure B-3
Design Fails in Hardware
Using probes, an LED, Vivado ILA
or some other method, determine if
user_lnk_up is asserted. When
user_lnk_up is High, it indicates
the core has achieved link up
meaning the LTSSM is in L0 state
and the data link layer is in the
DL_Active state.
Yes
Is user_lnk_up asserted?
(user_lnk_up = 1)
See “Link is Training Debug” section.
No
To eliminate FPGA configuration
as a root cause, perform a soft
restart of the system. Performing a
soft reset on the system will keep
power applied and forces
re-enumeration of the device.
Yes
Does a soft reset fix the problem?
(user_lnk_up = 1)
See "FPGA Configuration Time
Debug" section.
No
One reason user_reset stays
asserted other than the system
reset being asserted is due to a
faulty clock. This might keep the
PLL from locking which holds
user_reset asserted.
No
Is user_reset deasserted?
(user_reset = 0)
Multi-lane links are susceptible to
crosstalk and noise when all lanes
are switching during training.
A quick test for this is forcing one
lane operation. This can be done
by using an interposer or adapter
to isolate the upper lanes or use
a tape such as Scotch tape and
tape off the upper lanes on the
connector. If it is an embedded
board, remove the AC capacitors if
possible to isolate the lanes.
See "Clock Debug" section.
Yes
Yes
Is it a multi-lane link?
Force x1 Operation
Does user_lnk_up = 1 when using
as x1 only?
No
Yes
Do you have a link analyzer?
Yes
No
Use the link analyzer to monitor the training
sequence and to determine the point of failure.
Have the analyzer trigger on the first TS1 that it
recognizes and then compare the output to the
LTSSM state machine sequences outlined in
Chapter 4 of the PCI Express Base Specification.
Use Vivado Design Suite debug
feature to determine the
point of failure.
Figure B-3:
There are potentially issues
with the board layout causing
interference when all lanes are
switching. See board debug
suggestions.
Design Fails in Hardware Debug Flow Diagram
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Appendix B: Debugging
FPGA Configuration Time Debug
Device initialization and configuration issues can be caused by not having the FPGA
configured fast enough to enter link training and be recognized by the system. Section 6.6
of PCI Express Base Specification, rev. 2.1 [Ref 2] states two rules that might be impacted by
FPGA Configuration Time:
•
A component must enter the LTSSM Detect state within 20 ms of the end of the
Fundamental reset.
•
A system must guarantee that all components intended to be software visible at boot
time are ready to receive Configuration Requests within 100 ms of the end of
Conventional Reset at the Root Complex.
These statements basically mean the FPGA must be configured within a certain finite time,
and not meeting these requirements could cause problems with link training and device
recognition.
Configuration can be accomplished using an onboard PROM or dynamically using JTAG.
When using JTAG to configure the device, configuration typically occurs after the Chipset
has enumerated each peripheral. After configuring the FPGA, a soft reset is required to
restart enumeration and configuration of the device. A soft reset on a Windows based PC is
performed by going to Start > Shut Down and then selecting Restart.
To eliminate FPGA configuration as a root cause, you should perform a soft restart of the
system. Performing a soft reset on the system keeps power applied and forces
re-enumeration of the device. If the device links up and is recognized after a soft reset is
performed, then FPGA configuration is most likely the issue. Most typical systems use ATX
power supplies which provide some margin on this 100 ms window as the power supply is
normally valid before the 100 ms window starts. For more information on FPGA
configuration, see FPGA Configuration in Chapter 3.
Link is Training Debug
Figure B-4 shows the flowchart for link trained debug.
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Appendix B: Debugging
X-Ref Target - Figure B-4
Link is Training
(user_lnk_up = 1)
PCITREE and lspci scan the
the system and display devices
recognized during startup. These
tools show the PCI configuration
space and its settings within
the device.
Is the device recognized by the system?
Can it be seen by PCITREE (Windows) or
lspci (Linux)?
Yes
See “Data Transfer Failing Debug”
section.
No
To eliminate FPGA configuration
as a root cause, perform a soft
restart of the system. Performing a
soft reset on the system keeps
power applied and forces
re-enumeration of the device.
If this fixes the problem, then it is
likely the FPGA is not configured in
time for the host to access the card.
Does a soft reset fix the problem?
(user_lnk_up = 1)
Yes
See "FPGA Configuration Time
Debug" section.
No
The PIO design is known to work.
Often, the PIO design works when
a user design does not. This usually
indicates some parameter or resource
conflict due to settings used for the
user design configuration.
Recommended: Mirror the PIO
Vivado IP catalog settings into
the user design. Even though the
design might not function, it should
still be recognized by the system.
Does using the PIO example
design fix the problem?
Does mirroring the PIO
Vivado IP catalog settings for
the user design fix the problem?
Yes
No
Yes
Do you have a link analyzer?
No
Check for configuration settings
conflict. See the "Debugging
PCI Configuration Space Parameters"
section.
No
Yes
With no link analyzer, use the Vivado Design Suite
debug feature to gather the same information.
If the PIO design works, but mirroring the
configuration parameters does not fix the
problem, then attention should be focused on
the user application design. See the "Application
Requirements" section.
It is likely the problem is due to the device
not responding properly to some type of access. A
link analyzer allows the user to view the link traffic
and determine if something is incorrect. See
the "Using a Link Analyzer to Debug
Device Recognition Issues” section.
Figure B-4:
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Link Trained Debug Flow Diagram
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Appendix B: Debugging
FPGA Configuration Time Debug
Device initialization and configuration issues can be caused by not having the FPGA
configured fast enough to enter link training and be recognized by the system. Section 6.6
of PCI Express Base Specification, rev. 2.1 [Ref 2] states two rules that might be impacted by
FPGA Configuration Time:
•
A component must enter the LTSSM Detect state within 20 ms of the end of the
Fundamental reset.
•
A system must guarantee that all components intended to be software visible at boot
time are ready to receive Configuration Requests within 100 ms of the end of
Conventional Reset at the Root Complex.
These statements basically mean the FPGA must be configured within a certain finite time,
and not meeting these requirements could cause problems with link training and device
recognition.
Configuration can be accomplished using an onboard PROM or dynamically using JTAG.
When using JTAG to configure the device, configuration typically occurs after the Chipset
has enumerated each peripheral. After configuring the FPGA, a soft reset is required to
restart enumeration and configuration of the device. A soft reset on a Windows based PC is
performed by going to Start > Shut Down and then selecting Restart.
To eliminate FPGA configuration as a root cause, you should perform a soft restart of the
system. Performing a soft reset on the system keeps power applied and forces
re-enumeration of the device. If the device links up and is recognized after a soft reset is
performed, then FPGA configuration is most likely the issue. Most typical systems use ATX
power supplies which provides some margin on this 100 ms window as the power supply is
normally valid before the 100 ms window starts. For more information on FPGA
configuration, see FPGA Configuration in Chapter 3.
Clock Debug
One reason to not deassert the user_reset_out signal is that the fabric PLL (MMCM) and
Transceiver PLL have not locked to the incoming clock. To verify lock, monitor the
transceiver CPLLLOCK or QPLLLOCK output and the MMCM LOCK output. If the PLLs do not
lock as expected, it is necessary to ensure the incoming reference clock meets the
requirements in 7 Series FPGAs GTX/GTH Transceivers User Guide [Ref 12]. The REFCLK signal
should be routed to the dedicated reference clock input pins on the serial transceiver, and
the user design should instantiate the IBUFDS_GTE2 primitive in the user design. See the
7 Series FPGAs GTX/GTH Transceivers User Guide for more information on PCB layout
requirements, including reference clock requirements.
Reference clock jitter can potentially close both the TX and RX eyes, depending on the
frequency content of the phase jitter. Therefore, as clean a reference clock as possible must
be maintained. Reduce crosstalk on REFCLK by isolating the clock signal from nearby
high-speed traces. Maintain a separation of at least 25 mils from the nearest aggressor
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Appendix B: Debugging
signals. The PCI Special Interest Group website provides other tools for ensuring the
reference clocks are compliant to the requirements of the PCI Express Specification:
www.pcisig.com/specifications/pciexpress/compliance/compliance_library
Debugging PCI Configuration Space Parameters
Often, a user application fails to be recognized by the system, but the Xilinx PIO Example
design works. In these cases, the user application is often using a PCI configuration space
setting that is interfering with the system systems ability to recognize and allocate
resources to the card.
Xilinx solutions for PCI Express handle all configuration transactions internally and generate
the correct responses to incoming configuration requests. Chipsets have limits as to the
amount of system resources it can allocate and the core must be configured to adhere to
these limitations.
The resources requested by the Endpoint are identified by the BAR settings within the
Endpoint configuration space. You should verify that the resources requested in each BAR
can be allocated by the chipset. I/O BARs are especially limited so configuring a large I/O
BAR typically prevents the chipset from configuring the device. Generate a core that
implements a small amount of memory (approximately 2 KB) to identify if this is the root
cause.
The Class Code setting selected in the Vivado IDE can also affect configuration. The Class
Code informs the Chipset as to what type of device the Endpoint is. Chipsets might expect
a certain type of device to be plugged into the PCI Express slot and configuration might fail
if it reads an unexpected Class Code. The BIOS could be configurable to work around this
issue.
Use the PIO design with default settings to rule out any device allocation issues. The PIO
design default settings have proven to work in all systems encountered when debugging
problems. If the default settings allow the device to be recognized, then change the PIO
design settings to match the intended user application by changing the PIO configuration in
the Vivado IDE. Trial and error might be required to pinpoint the issue if a link analyzer is not
available.
Using a link analyzer, it is possible to monitor the link traffic and possibly determine when
during the enumeration and configuration process problems occur.
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Appendix B: Debugging
Application Requirements
During enumeration, it is possible for the chipset to issue transaction layer packet (TLP)
traffic that is passed from the core to the backend application. A common oversight when
designing custom backend applications is to not have logic which handles every type
incoming request. As a result, no response is created and problems arise. The PIO design has
the necessary backend functions to respond correctly to any incoming request. It is the
responsibility of the application to generate the correct response. These packet types are
presented to the application:
•
Requests targeting the Expansion ROM (if enabled)
•
Message TLPs
•
Memory or I/O requests targeting a BAR
•
All completion packets
The PIO design, can be used to rule out any of these types of concerns, as the PIO design
responds to all incoming transactions to the user application in some way to ensure the host
receives the proper response allowing the system to progress. If the PIO design works, but
the custom application does not, some transaction is not being handled properly.
The Vivado Lab Edition should be implemented on the wrapper Receive AXI4-Stream
interface to identify if requests targeting the backend application are drained and
completed successfully. The AXI4-Stream interface signals that should be probed in the
Vivado Lab Edition are defined in Table B-1, page 346.
Using a Link Analyzer to Debug Device Recognition Issues
In cases where the link is up (user_lnk_up = 1), but the device is not recognized by the
system, a link analyzer can help solve the issue. It is likely the FPGA is not responding
properly to some type of access. The link view can be used to analyze the traffic and see if
anything looks out of place.
To focus on the issue, it might be necessary to try different triggers. Here are some trigger
examples:
•
Trigger on the first INIT_FC1 and/or UPDATE_FC in either direction. This allows the
analyzer to begin capture after link up.
•
The first TLP normally transmitted to an Endpoint is the Set Slot Power Limit Message.
This usually occurs before Configuration traffic begins. This might be a good trigger
point.
•
Trigger on Configuration TLPs.
•
Trigger on Memory Read or Memory Write TLPs.
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Appendix B: Debugging
Data Transfer Failing Debug
Figure B-5 shows the flowchart for data transfer debug.
X-Ref Target - Figure B-5
Link is Up (user_lnk_up = 1)
Device is recognized by system.
Data Transfers failing.
The most often cause of a system
freeze or hang is due to a
completion timeout occurring
on the host. This happens when
the host issues a non-posted
transaction (usually a memory
read) to the Endpoint and the
Endpoint's user application does
not properly respond.
Is the system freezing or hanging?
Yes
Ensure that completions are returned
for all incoming Non-Posted traffic.
No
If user_lnk_up is toggling, it usually
means the physical link is marginal.
In these cases, the link can be
established but might then fail once
traffic begins to flow. Use Vivado ILA
or probe user_lnk_up to a logic
analyzer and determine if it is toggling.
Is use_lnk_up toggling?
Yes
Link could be marginal and packets
are failing to pass LCRC check.
No
Errors are reported to the user
interface on the output cfg_dstatus[3:0].
This is a copy of the device status
register. Use Vivado ILA to monitor
this bus for errors.
Fatal Error? Blue screen?
Other errors?
Yes
Errors flagged by the core are due
to problems on the receive datapath.
Use a link analyzer if possible to
check incoming packets. See the
"Identifying Errors" section.
No
Receive
Is the problem with receiving
or transmitting TLPs?
Do incoming packets appear
on the AXI receive interface?
Transmit
Do outgoing packets arrive
at destination?
No
No
If read or write transactions do not
appear on the AXI interface, it means
that most likely the incoming packet
did not hit a BAR. Verify incoming
TLP addresses against BAR
allocation.
If completion packets fail to reach their
destination, ensure the packet
contained the correct requester ID as
captured from the original
Non-Posted TLP.
A memory write that misses a BAR
results in a Non-Fatal error message.
A non-posted transaction that misses a
BAR results in a Completion with
UR status.
Figure B-5:
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If other packets fail, ensure the address
targeted is valid.
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Appendix B: Debugging
Identifying Errors
Hardware symptoms of system lock up issues are indicated when the system hangs or a blue
screen appears (PC systems). The PCI Express Base Specification, rev. 2.1 [Ref 2] requires that
error detection be implemented at the receiver. A system lock up or hang is commonly the
result of a Fatal Error and is reported in bit 2 of the receiver Device Status register. Using the
Vivado Lab Edition, monitor the core device status register to see if a fatal error is being
reported.
A fatal error reported at the Root complex implies an issue on the transmit side of the EP.
The Root Complex Device Status register can often times be seen using PCITree (Windows)
or LSPCI (Linux). If a fatal error is detected, see the Transmit section. A Root Complex can
often implement Advanced Error Reporting, which further distinguishes the type of error
reported. AER provides valuable information as to why a certain error was flagged and is
provided as an extended capability within a devices configuration space. Section 7.10 of the
PCI Express Base Specification, rev. 2.1 provides more information on AER registers.
Transmit
Fatal Error Detected on Root or Link Partner
Check to make sure the TLP is correctly formed and that the payload (if one is attached)
matches what is stated in the header length field. The Endpoints device status register does
not report errors created by traffic on the transmit channel.
These signals should be monitored on the Transmit interface to verify all traffic being
initiated is correct. See Table 2-9, page 16 for signal descriptions.
•
user_lnk_up
•
s_axis_tx_tlast
•
s_axis_tx_tdata
•
s_axis_tx_trb
•
s_axis_tx_tvalid
•
s_axis_tx_tready
Fatal Error Not Detected
Ensure that the address provided in the TLP header is valid. The kernel mode driver attached
to the device is responsible for obtaining the system resources allocated to the device. In a
Bus Mastering design, the driver is also responsible for providing the application with a
valid address range. System hangs or blue screens might occur if a TLP contains an address
that does not target the designated address range for that device.
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Appendix B: Debugging
Receive
Xilinx solutions for PCI Express provide the Device Status register to the application on
CFG_DSTATUS[3:0].
Table B-1:
Description of CFG_DSTATUS[3:0]
CFG_DSTATUS[3:0]
Description
CFG_DSTATUS[0]
Correctable Error Detected
CFG_DSTATUS[1]
Non-Fatal Error Detected
CFG_DSTATUS[2]
Fatal Error Detected
CFG_DSTATUS[3]
UR Detected
System lock up conditions due to issues on the receive channel of the PCI Express core are
often result of an error message being sent upstream to the root. Error messages are only
sent when error reporting is enabled in the Device Control register.
A fatal condition is reported if any of these events occur:
•
Training Error
•
DLL Protocol Error
•
Flow Control Protocol Error
•
Malformed TLP
•
Receiver Overflow
The first four bullets are not common in hardware because both Xilinx solutions for PCI
Express and connected components have been thoroughly tested in simulation and
hardware. However, a receiver overflow is a possibility. You must follow the requirements
discussed in Receiver Flow Control Credits Available in Chapter 3 when issuing memory
reads.
Non-Fatal Errors
This subsection lists conditions reported as Non-Fatal errors. See the PCI Express Base
Specification, rev. 2.1 for more details.
If the error is being reported by the root, the AER registers can be read to determine the
condition that led to the error. Use a tool such as HWDIRECT, discussed in Third-Party Tools,
page 332, to read the AER registers of the root. Chapter 7 of the PCI Express Base
Specification defines the AER registers. If the error is signaled by the Endpoint, debug ports
are available to help determine the specific cause of the error.
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Appendix B: Debugging
Correctable Non-Fatal Errors
Correctable Non-Fatal errors are:
•
Receiver Error
•
Bad TLP
•
Bad DLLP
•
Replay Timeout
•
Replay NUM Rollover
The first three errors listed above are detected by the receiver and are not common in
hardware systems. The replay error conditions are signaled by the transmitter. If an ACK is
not received for a packet within the allowed time, it is replayed by the transmitter.
Throughput can be reduced if many packets are being replayed, and the source can usually
be determined by examining the link analyzer or Vivado Lab Edition captures.
Uncorrectable Non-Fatal Errors
Uncorrectable Non-Fatal errors are:
•
Poisoned TLP
•
Received ECRC Check Failed
•
Unsupported Request (UR)
•
Completion Timeout
•
Completer Abort
•
Unexpected Completion
•
ACS Violation
An unsupported request usually indicates that the address in the TLP did not fall within the
address space allocated to the BAR. This often points to an issue with the address
translation performed by the driver. Ensure also that the BAR has been assigned correctly by
the root at start-up. LSPCI or PCItree discussed in Third-Party Tools, page 332 can be used
to read the BAR values for each device.
A completion timeout indicates that no completion was returned for a transmitted TLP and
is reported by the requester. This can cause the system to hang (could include a blue screen
on Windows) and is usually caused when one of the devices locks up and stops responding
to incoming TLPs. If the root is reporting the completion timeout, the Vivado Lab Edition
can be used to investigate why the user application did not respond to a TLP (for example,
the user application is busy, there are no transmit buffers available, or s_axis_tx_tready is
deasserted). If the Endpoint is reporting the Completion timeout, a link analyzer would show
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Appendix B: Debugging
the traffic patterns during the time of failure and would be useful in determining the root
cause.
Next Steps
If the debug suggestions listed previously do not resolve the issue, open a support case or
visit the Xilinx User Community forums to have the appropriate Xilinx expert assist with the
issue.
To create a technical support case in WebCase, see the Xilinx website at:
www.xilinx.com/support/clearexpress/websupport.htm
Items to include when opening a case:
°
Detailed description of the issue and results of the steps listed above.
°
Vivado Lab Edition captures taken in the steps above.
To discuss possible solutions, use the Xilinx User Community:
forums.xilinx.com/xlnx/
Additional Transceiver Control and Status Ports
Table B-2 describes the ports used to debug transceiver-related issues.
RECOMMENDED: Debugging transceiver-related issues is recommended for advanced users only.
For more information about these GT debug signals, see the 7 Series FPGAs GTX/GTH
Transceivers User Guide (UG476) [Ref 12], and the 7 Series FPGAs GTP Transceivers User
Guide (UG482) [Ref 13].
Table B-2:
Additional Transceiver Control and Status Ports
Port
Direction Width
(I/O)
Description
pipe_txprbssel
I
3
PRBS input
pipe_rxprbssel
I
3
PRBS input
pipe_rxprbsforceerr
I
1
PRBS input
pipe_rxprbscntrreset
I
1
PRBS input
pipe_loopback
I
1
PIPE loopback.
pipe_rxprbserr
O
1
PRBS output.
pipe_rst_fsm
O
Should be examined if PIPE_RST_IDLE is stuck at 0.
pipe_qrst_fsm
O
Should be examined if PIPE_RST_IDLE is stuck at 0.
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Appendix B: Debugging
Table B-2:
Additional Transceiver Control and Status Ports (Cont’d)
Port
Direction Width
(I/O)
Description
pipe_sync_fsm_tx
O
Should be examined if PIPE_RST_FSM stuck at
11'b10000000000, or PIPE_RATE_FSM stuck at
24'b000100000000000000000000.
pipe_sync_fsm_rx
O
Deprecated.
pipe_drp_fsm
O
Should be examined if PIPE_RATE_FSM is stuck at
100000000.
pipe_rst_idle
O
Wrapper is in IDLE state if PIPE_RST_IDLE is High.
pipe_qrst_idle
O
Wrapper is in IDLE state if PIPE_QRST_IDLE is High.
pipe_rate_idle
O
Wrapper is in IDLE state if PIPE_RATE_IDLE is High.
O
Generic debug ports to assist debug. These are generic
debug ports to bring out internal PIPE Wrapper signals,
such as raw GT signals. DEBUG_0 to DEBUGT_9 are
intended for per lane signals. The bus width of these
generic debug ports depends on the number of lanes
configured in the wrapper.
O
Generic debug ports to assist debug. These are generic
debug ports to bring out internal PIPE Wrapper signals,
such as raw GT signals. DEBUG_0 to DEBUGT_9 are
intended for per lane signals.The bus width of these
generic debug ports depends on the number of lanes
configured in the wrapper.
O
Generic debug ports to assist debug. These are generic
debug ports to bring out internal PIPE Wrapper signals,
such as raw GT signals. DEBUG_0 to DEBUGT_9 are
intended for per lane signals. The bus width of these
generic debug ports depends on the number of lanes
configured in the wrapper.
O
Generic debug ports to assist debug. These are generic
debug ports to bring out internal PIPE Wrapper signals,
such as raw GT signals. DEBUG_0 to DEBUGT_9 are
intended for per lane signals. The bus width of these
generic debug ports depends on the number of lanes
configured in the wrapper.
O
Generic debug ports to assist debug. These generic debug
ports bring out internal PIPE Wrapper signals, such as raw
GT signals. DEBUG_0 to DEBUGT_9 are intended for per
lane signals. The bus width of these generic debug ports
depends on the number of lanes configured in the
wrapper.
O
Generic debug ports to assist debug. These generic debug
ports bring out internal PIPE Wrapper signals, such as raw
GT signals. DEBUG_0 to DEBUGT_9 are intended for per
lane signals. The bus width of these generic debug ports
depends on the number of lanes configured in the
wrapper.
PIPE_DEBUG_0/gt_txresetdone
PIPE_DEBUG_1/gt_rxresetdone
PIPE_DEBUG_2/gt_phystatus
PIPE_DEBUG_3/gt_rxvalid
PIPE_DEBUG_4/gt_txphaligndone
PIPE_DEBUG_5/gt_rxphaligndone
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Appendix B: Debugging
Table B-2:
Additional Transceiver Control and Status Ports (Cont’d)
Port
Direction Width
(I/O)
Description
O
Generic debug ports to assist debug. These generic debug
ports bring out internal PIPE Wrapper signals, such as raw
GT signals. DEBUG_0 to DEBUGT_9 are intended for per
lane signals. The bus width of these generic debug ports
depends on the number of lanes configured in the
wrapper.
O
Generic debug ports to assist debug. These generic debug
ports bring out internal PIPE Wrapper signals, such as raw
GT signals. DEBUG_0 to DEBUGT_9 are intended for per
lane signals. The bus width of these generic debug ports
depends on the number of lanes configured in the
wrapper.
O
Generic debug ports to assist debug. These generic debug
ports bring out internal PIPE Wrapper signals, such as raw
GT signals. DEBUG_0 to DEBUGT_9 are intended for per
lane signals. The bus width of these generic debug ports
depends on the number of lanes configured in the
wrapper.
PIPE_DEBUG_9/PIPE_TXELECIDLE
O
Generic debug ports to assist debug. These generic debug
ports bring out internal PIPE Wrapper signals, such as raw
GT signals. DEBUG_0 to DEBUGT_9 are intended for per
lane signals. The bus width of these generic debug ports
depends on the number of lanes configured in the
wrapper.
pipe_txinhibit
I
PIPE_DEBUG_6/gt_rxcommadet
PIPE_DEBUG_7/gt_rdy
PIPE_DEBUG_8/user_rx_converge
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Appendix C
Managing Receive-Buffer Space for
Inbound Completions
The PCI Express® Base Specification [Ref 2] requires all Endpoints to advertise infinite Flow
Control credits for received Completions to their link partners. This means that an Endpoint
must only transmit Non-Posted Requests for which it has space to accept Completion
responses. This appendix describes how a user application can manage the receive-buffer
space in the 7 Series Integrated Block for PCIe core to fulfill this requirement.
General Considerations and Concepts
Completion Space
Table C-1 defines the completion space reserved in the receive buffer by the core. The
values differ depending on the different Capability Max Payload Size settings of the core
and the performance level that you selected. If you chooses to not have TLP Digests (ECRC)
removed from the incoming packet stream, the TLP Digests (ECRC) must be accounted for
as part of the data payload. Values are credits, expressed in decimal.
Table C-1:
Receiver-Buffer Completion Space
Capability Max Payload Size
(bytes)
Performance Level: Good
Performance Level: High
Cpl. Hdr.
(Total_CplH)
Cpl. Data
(Total_CplD)
Cpl. Hdr.
(Total_CplH)
Cpl. Data
(Total_CplD)
128
36
77
36
154
256
36
77
36
154
512
36
154
36
308
1024
36
308
36
616
Maximum Request Size
A Memory Read cannot request more than the value stated in Max_Request_Size, which is
given by Configuration bits cfg_dcommand[14:12] as defined in Table C-2. If the user
application does not read the Max_Request_Size value, it must use the default value of 128
bytes.
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Appendix C: Managing Receive-Buffer Space for Inbound Completions
Table C-2:
Max_Request_Size Settings
cfg_dcommand[14:12]
Max_Request_Size
Bytes
DW
QW
Credits
000b
128
32
16
8
001b
256
64
32
16
010b
512
128
64
32
011b
1024
256
128
64
100b
2048
512
256
128
101b
4096
1024
512
256
Reserved
110b–111b
Read Completion Boundary
A Memory Read can be answered with multiple Completions, which when put together
return all requested data. To make room for packet-header overhead, the user application
must allocate enough space for the maximum number of Completions that might be
returned.
To make this process easier, the PCI Express Base Specification quantizes the length of all
Completion packets such that each must start and end on a naturally aligned Read
Completion Boundary (RCB), unless it services the starting or ending address of the original
request. The value of RCB is determined by Configuration bit cfg_lcommand[3] as defined in
Table C-3. If the user application does not read the RCB value, it must use the default value
of 64 bytes.
Table C-3:
Read Completion Boundary Settings
cfg_lcommand[3]
Read Completion Boundary
Bytes
DW
QW
Credits
0
64
16
8
4
1
128
32
16
8
When calculating the number of Completion credits a Non-Posted Request requires, you
must determine how many RCB-bounded blocks the Completion response might be
required, which is the same as the number of Completion Header credits required.
Methods of Managing Completion Space
A user application can choose one of five methods to manage receive-buffer Completion
space, as listed in Table C-4. For convenience, this discussion refers to these methods as
LIMIT_FC, PACKET_FC, RCB_FC, DATA_FC, and STREAM_FC. Each has advantages and
disadvantages that you need to consider when developing the user application.
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Appendix C: Managing Receive-Buffer Space for Inbound Completions
Table C-4:
Managing Receive Completion Space Methods
Method
Description
Advantage
Disadvantage
LIMIT_FC
Limit the total number of
outstanding NP Requests
Simplest method to
implement in user logic
Much Completion
capacity goes unused
PACKET_FC
Track the number of
outstanding CplH and CplD
credits; allocate and deallocate
on a per-packet basis
Relatively simple user
logic; finer allocation
granularity means less
wasted capacity than
LIMIT_FC
As with LIMIT_FC,
credits for an NP are
still tied up until the
Request is completely
satisfied
RCB_FC
Track the number of
outstanding CplH and CplD
credits; allocate and deallocate
on a per-RCB basis
Ties up credits for less
time than PACKET_FC
More complex user
logic than LIMIT_FC or
PACKET_FC
DATA_FC
Track the number of
outstanding CplH and CplD
credits; allocate and deallocate
on a per-RCB basis
Lowest amount of
wasted capacity
More complex user
logic than LIMIT_FC,
PACKET_FC, and RCB_FC
Very high performance
The user application
must accept and
process Downstream
Completion and Posted
Transactions at line rate;
Most complex user
logic
STREAM_FC
Stream packets out of the core
at line rate
LIMIT_FC Method
The LIMIT_FC method is the simplest to implement. The user application assesses the
maximum number of outstanding Non-Posted Requests allowed at one time, MAX_NP. To
calculate this value, perform these steps:
1. Determine the number of CplH credits required by a Max_Request_Size packet:
Max_Header_Count = ceiling(Max_Request_Size / RCB)
2. Determine the greatest number of maximum-sized Completions supported by the CplD
credit pool:
Max_Packet_Count_CplD = floor(CplD / Max_Request_Size)
3. Determine the greatest number of maximum-sized Completions supported by the CplH
credit pool:
Max_Packet_Count_CplH = floor(CplH / Max_Header_Count)
4. Use the smaller of the two quantities from steps 2 and 3 to obtain the maximum number
of outstanding Non-Posted requests:
MAX_NP = min(Max_Packet_Count_CplH, Max_Packet_Count_CplD)
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Appendix C: Managing Receive-Buffer Space for Inbound Completions
With knowledge of MAX_NP, the user application can load a register NP_PENDING with zero
at reset and make sure it always stays with the range 0 to MAX_NP. When a Non-Posted
Request is transmitted, NP_PENDING decrements by one. When all Completions for an
outstanding NP Request are received, NP_PENDING increments by one.
Although this method is the simplest to implement, it can waste the greatest receiver space
because an entire Max_Request_Size block of Completion credit is allocated for each
Non-Posted Request, regardless of actual request size. The amount of waste becomes
greater when the user application issues a larger proportion of short Memory Reads (on the
order of a single DWORD), I/O Reads and I/O Writes.
PACKET_FC Method
The PACKET_FC method allocates blocks of credit in finer granularities than LIMIT_FC, using
the receive Completion space more efficiently with a small increase in user logic.
Start with two registers, CPLH_PENDING and CPLD_PENDING, (loaded with zero at reset),
and then perform these steps:
1. When the user application needs to send an NP request, determine the potential number
of CplH and CplD credits it might require:
NP_CplH = ceiling[((Start_Address mod RCB) + Request_Size) / RCB]
NP_CplD = ceiling[((Start_Address mod 16 bytes) + Request_Size) /16 bytes]
(except I/O Write, which returns zero data)
The modulo and ceiling functions ensure that any fractional RCB or credit blocks are
rounded up. For example, if a Memory Read requests 8 bytes of data from address 7Ch,
the returned data can potentially be returned over two Completion packets (7Ch-7Fh,
followed by 80h-83h). This would require two RCB blocks and two data credits.
2. Check these:
CPLH_PENDING + NP_CplH < Total_CplH (from Table C-1)
CPLD_PENDING + NP_CplD < Total_CplD (from Table C-1)
3. If both inequalities are true, transmit the Non-Posted Request, and increase
CPLH_PENDING by NP_CplH and CPLD_PENDING by NP_CplD. For each NP Request
transmitted, keep NP_CplH and NP_CplD for later use.
4. When all Completion data is returned for an NP Request, decrease CPLH_PENDING and
CPLD_PENDING accordingly.
This method is less wasteful than LIMIT_FC but still ties up all of an NP Request Completion
space until the entire request is satisfied. RCB_FC and DATA_FC provide finer deallocation
granularity at the expense of more logic.
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Appendix C: Managing Receive-Buffer Space for Inbound Completions
RCB_FC Method
The RCB_FC method allocates and de-allocates blocks of credit in RCB granularity. Credit is
freed on a per-RCB basis.
As with PACKET_FC, start with two registers, CPLH_PENDING and CPLD_PENDING (loaded
with zero at reset).
1. Calculate the number of data credits per RCB:
CplD_PER_RCB = RCB / 16 bytes
2. When the user application needs to send an NP request, determine the potential number
of CplH credits it might require. Use this to allocate CplD credits with RCB granularity:
NP_CplH = ceiling[((Start_Address mod RCB) + Request_Size) / RCB]
NP_CplD = NP_CplH × CplD_PER_RCB
3. Check these:
CPLH_PENDING + NP_CplH < Total_CplH
CPLD_PENDING + NP_CplD < Total_CplD
4. If both inequalities are true, transmit the Non-Posted Request, increase CPLH_PENDING
by NP_CplH and CPLD_PENDING by NP_CplD.
5. At the start of each incoming Completion, or when that Completion begins at or crosses
an RCB without ending at that RCB, decrease CPLH_PENDING by 1 and CPLD_PENDING
by CplD_PER_RCB. Any Completion could cross more than one RCB. The number of RCB
crossings can be calculated by:
RCB_CROSSED = ceiling[((Lower_Address mod RCB) + Length) / RCB]
Lower_Address and Length are fields that can be parsed from the Completion header.
Alternatively, you can load a register CUR_ADDR with Lower_Address at the start of each
incoming Completion, increment per DW or QW as appropriate, then count an RCB
whenever CUR_ADDR rolls over.
This method is less wasteful than PACKET_FC but still provides an RCB granularity. If a user
application transmits I/O requests, the user application could adopt a policy of only
allocating one CplD credit for each I/O Read and zero CplD credits for each I/O Write. The
user application would have to match each incoming Completion’s Tag with the Type
(Memory Write, I/O Read, I/O Write) of the original NP Request.
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Appendix C: Managing Receive-Buffer Space for Inbound Completions
DATA_FC Method
The DATA_FC method provides the finest allocation granularity at the expense of logic.
As with PACKET_FC and RCB_FC, start with two registers, CPLH_PENDING and
CPLD_PENDING (loaded with zero at reset).
1. When the user application needs to send an NP request, determine the potential number
of CplH and CplD credits it might require:
NP_CplH = ceiling[((Start_Address mod RCB) + Request_Size) / RCB]
NP_CplD = ceiling[((Start_Address mod 16 bytes) + Request_Size) / 16 bytes]
(except I/O Write, which returns zero data)
2. Check these:
CPLH_PENDING + NP_CplH < Total_CplH
CPLD_PENDING + NP_CplD < Total_CplD
3. If both inequalities are true, transmit the Non-Posted Request, increase CPLH_PENDING
by NP_CplH and CPLD_PENDING by NP_CplD.
4. At the start of each incoming Completion, or when that Completion begins at or crosses
an RCB without ending at that RCB, decrease CPLH_PENDING by 1. The number of RCB
crossings can be calculated by:
RCB_CROSSED = ceiling[((Lower_Address mod RCB) + Length) / RCB]
Lower_Address and Length are fields that can be parsed from the Completion header.
Alternatively, you can load a register CUR_ADDR with Lower_Address at the start of each
incoming Completion, increment per DW or QW as appropriate, then count an RCB
whenever CUR_ADDR rolls over.
5. At the start of each incoming Completion, or when that Completion begins at or crosses
at a naturally aligned credit boundary, decrease CPLD_PENDING by 1. The number of
credit-boundary crossings is given by:
DATA_CROSSED = ceiling[((Lower_Address mod 16 B) + Length) / 16 B]
Alternatively, you can load a register CUR_ADDR with Lower_Address at the start of each
incoming Completion, increment per DW or QW as appropriate, then count an RCB
whenever CUR_ADDR rolls over each 16-byte address boundary.
This method is the least wasteful but requires the greatest amount of user logic. If even finer
granularity is desired, you can scale the Total_CplD value by 2 or 4 to get the number of
Completion QWORDs or DWORDs, respectively, and adjust the data calculations
accordingly.
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Appendix C: Managing Receive-Buffer Space for Inbound Completions
STREAM_FC Method
When configured as an Endpoint, user applications can maximize Downstream (away from
Root Complex) data throughput by streaming Memory Read Transactions Upstream
(towards the Root Complex) at the highest rate allowed on the Integrated Block Transaction
transmit interface. Streaming Memory Reads are allowed only if m_axis_rx_tready can
be held asserted; so that Downstream Completion Transactions, along with Posted
Transactions, can be presented on the integrated block receive transaction interface and
processed at line rate. Asserting m_axis_rx_tready in this manner guarantees that the
Completion space within the receive buffer is not oversubscribed (that is, Receiver Overflow
does not occur).
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Appendix D
PCIE_2_1 Port Descriptions
This appendix describes the physical interfaces visible on the 7 Series FPGAs Integrated
Block software primitive, PCIE_2_1.
This appendix contains these sections:
•
Clock and Reset Interface
•
Transaction Layer Interface
•
Block RAM Interface
•
GTX Transceiver Interface
•
Configuration Management Interface
•
Dynamic Reconfiguration Port Interface
•
TL2 Interface Ports
Clock and Reset Interface
Table D-1 defines the ports in the Clock and Reset interface.
Table D-1:
Clock and Reset Interface Port Descriptions
Port
Direction Clock Domain
Description
CMRSTN
Input
USERCLK
Configuration Management reset (active-Low). This
input resets the PCI™ Configuration Space of the
integrated block.
CMSTICKYRSTN
Input
USERCLK
Sticky configuration reset (active-Low). This input resets
the sticky registers in the PCI Configuration Space of the
integrated block.
DLRSTN
Input
USERCLK
Data Link Layer reset (active-Low). This input resets the
Data Link Layer (DLL) of the integrated block.
FUNCLVLRSTN
Input
USERCLK
Not supported. This input must be tied High.
PIPECLK
Input
PIPECLK
PIPE interface clock.
Output
PIPECLK
Received hot reset. When asserted, this output indicates
an in-band hot reset has been received.
PLRECEIVEDHOTRST
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Appendix D: PCIE_2_1 Port Descriptions
Table D-1:
Clock and Reset Interface Port Descriptions (Cont’d)
Port
Direction Clock Domain
Description
PLRSTN
Input
PIPECLK
Physical Layer reset (active-Low). This input resets the
Physical Layer of the integrated block.
PLTRANSMITHOTRST
Input
PIPECLK
Transmit hot reset. When asserted, this input directs the
integrated block to transmit an in-band hot reset.
Output
USERCLK
Not supported.
SYSRSTN
Input
NONE
Asynchronous system reset (active-Low). When this input
is asserted the integrated block is reset.
TLRSTN
Input
USERCLK
Transaction Layer reset (active-Low). This input resets the
Transaction Layer of the integrated block.
USERCLK
Input
USERCLK
User interface clock.
USERCLK2
Input
USERCLK
User interface clock 2.
USERRSTN
Output
USERCLK
User interface reset (active-Low). This output should be
used to reset the user design logic (it is asserted when
the integrated block is reset).
RECEIVEDFUNCLVLRSTN
Transaction Layer Interface
Packets are presented to and received from the integrated block Transaction Layer through
the Transaction Layer interface. Table D-2 defines the ports in the Transaction Layer
interface.
Table D-2:
Transaction Layer Interface Port Descriptions
Port
Direction Clock Domain
Description
TRNFCCPLD[11:0]
Output
USERCLK
Completion Data Flow Control Credits. This output contains the
number of Completion Data FC credits for the selected flow control
type.
TRNFCCPLH[7:0]
Output
USERCLK
Completion Header Flow Control Credits. This output contains the
number of Completion Header FC credits for the selected flow
control type.
TRNFCNPD[11:0]
Output
USERCLK
Non-Posted Data Flow Control Credits. This output contains the
number of Non-Posted Data FC credits for the selected flow
control type.
TRNFCNPH[7:0]
Output
USERCLK
Non-Posted Header Flow Control Credits. This output contains the
number of Non-Posted Header FC credits for the selected flow
control type.
TRNFCPD[11:0]
Output
USERCLK
Posted Data Flow Control Credits. This output contains the number
of Posted Data FC credits for the selected flow control type.
TRNFCPH[7:0]
Output
USERCLK
Posted Header Flow Control Credits. This output contains the
number of Posted Header FC credits for the selected flow control
type.
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Appendix D: PCIE_2_1 Port Descriptions
Table D-2:
Transaction Layer Interface Port Descriptions (Cont’d)
Port
TRNFCSEL[2:0]
Direction Clock Domain
Description
Input
USERCLK
Flow Control Informational Select. This input selects the type of
flow control information presented on the TRNFC* signals. Valid
values are:
• 000b: Receive buffer available space
• 001b: Receive credits granted to the link partner
• 010b: Receive credits consumed
• 100b: Transmit user credits available
• 101b: Transmit credit limit
• 110b: Transmit credits consumed
TRNLNKUP
Output
USERCLK
Link status output (active-High). When this output is asserted, the
Data Link Control and Management State Machine (DLCMSM) is in
the DLACTIVE state.
TRNRBARHIT[6:0]
Output
USERCLK
Receive BAR Hit (active-High). This output indicates the BAR(s)
targeted by the current receive transaction:
• TRNRBARHIT[0]: BAR0
• TRNRBARHIT[1]: BAR1
• TRNRBARHIT[2]: BAR2
• TRNRBARHIT[3]: BAR3
• TRNRBARHIT[4]: BAR4
• TRNRBARHIT[5]: BAR5
• TRNRBARHIT[6]: Expansion ROM Address
• TRNRBARHIT[7]: Reserved for future use
If two BARs are configured into a single 64-bit address, both
corresponding TRNRBARHITN bits are asserted.
TRNRD[127:0]
Output
USERCLK
Receive Data. This bus contains the packet data being received.
TRNRDSTRDY
Input
USERCLK
Receive Destination Ready (active-High). This input is asserted to
indicate that the user application is ready to accept data on
TRNRD. Simultaneous assertion of TRNRSRCRDY and
TRNRDSTRDY marks the successful transfer of data on TRNRD.
TRNRECRCERR
Output
USERCLK
Receive ECRC Error (active-High). When asserted, this output
indicates the current packet in progress has an ECRC error. It is
asserted by the integrated block at the packet EOF.
TRNREOF
Output
USERCLK
Receive End-of-Frame (active-High). When asserted, this output
indicates the end of a packet.
TRNRERRFWD
Output
USERCLK
Receive Error Forward (active-High). This output marks the current
packet in progress as error-poisoned. It is asserted by the
integrated block for the entire length of the packet.
TRNRFCPRET
Input
USERCLK2
Receive Posted Flow Control Credit Return. When asserted for one
cycle, this input sets a condition that allows the posted credits to
be transmitted to the link partner. The condition is cleared when
the posted flow control credits are transmitted.
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Appendix D: PCIE_2_1 Port Descriptions
Table D-2:
Transaction Layer Interface Port Descriptions (Cont’d)
Port
Direction Clock Domain
Description
TRNRNPOK
Input
USERCLK
Receive Non-Posted OK (active-High). The user application asserts
this input whenever it is ready to accept a Non-Posted Request
packet. This allows Posted and Completion packets to bypass
Non-Posted packets in the inbound queue if necessitated by the
user application. When the user application approaches a state
where it is unable to service Non-Posted Requests, it must deassert
TRNRNPOK one clock cycle before the integrated block presents
TRNREOF of the last Non-Posted TLP the user application can
accept.
TRNRNPREQ
Input
USERCLK2
Receive Non-Posted Request. When asserted, this input requests
one non-posted TLP from the integrated block.
TRNRREM[1:0]
Output
USERCLK2
Receive Data Word Enable. This output is valid only if both
TRNREOF and TRNRDSTRDY are asserted. Bit 1 is valid only when
the datapath is 128 bits.
When combined with TRNREOF and TRNRSOF, this output
indicates which words of the TRNRD are valid.
• 64-bit interface:
TRNRREM[0] = 1, packet data on all of TRNRD[63:0]
TRNRREM[0] = 0, packet data only on TRNRD[63:32]
• 128-bit interface:
TRNRREM[1]: Valid only if TRNRSRCRDY and TRNRDSTRDY are
asserted. When asserted along with TRNRSOF or TRNREOF,
indicates the location of start-of-frame (SOF) and/or
end-of-frame (EOF) within the beat.
° TRNRREM[1] = 1: Indicates TRNRD[127:64] has SOF and/or
TRNRD[63:0] has EOF
° TRNRREM[1] = 0: Indicates TRNRD[127:64] has EOF and/or
TRNRD[63:0] has SOF
TRNRREM[0]: Valid only if TRNREOF, TRNRSRCRDY, and
TRNRDSTRDY are all asserted
If TRNRREM[1] = 1:
° TRNRREM[0] = 1, packet data is on all of TRNRD[127:0]
° TRNRREM[0] = 0, packet data is only on TRNRD[127:32]
If TRNRREM[1] = 0:
° TRNRREM[0] = 1, packet data on all of TRNRD[127:64]
° TRNRREM[0] = 0, packet data only on TRNRD[127:96]
TRNRSOF
Output
USERCLK
Receive Start-of-Frame (active-High). When asserted, this output
indicates the start of a packet.
TRNRSRCDSC
Output
USERCLK
Receive Source Discontinue (active-High). When asserted, this
output indicates that the integrated block is aborting the current
packet transfer. It is asserted when the physical link is going into
reset.
TRNRSRCRDY
Output
USERCLK
Receive Source Ready (active-High). When asserted, this output
indicates that the integrated block is presenting valid data on
TRNRD.
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Appendix D: PCIE_2_1 Port Descriptions
Table D-2:
Transaction Layer Interface Port Descriptions (Cont’d)
Port
TRNTBUFAV[5:0]
Direction Clock Domain
Description
Output
USERCLK
Transmit Buffers Available. This output provides the number of
transmit buffers available in the integrated block. The maximum
number is 32. Each transmit buffer can accommodate one TLP up
to the supported maximum payload size.
TRNTCFGGNT
Input
USERCLK
Transmit Configuration Grant (active-High). The user application
asserts this input in response to TRNTCFGREQ, to allow the
integrated block to transmit an internally generated TLP. If the user
does not need to postpone internally generated TLPs, this signal
can be continuously asserted.
TRNTCFGREQ
Output
USERCLK
Transmit Configuration Request (active-High). This output is
asserted when the integrated block is ready to transmit a
Configuration Completion or other internally generated TLP.
TRNTD[127:0]
Input
USERCLK
Transmit Data. This bus contains the packet data to be transmitted.
Output
USERCLK
Transmit Destination Ready (active-High). When asserted, this
output indicates that the integrated block is ready to accept data
on TRNTD. Simultaneous assertion of TRNTSRCRDY and
TRNTDSTRDY marks a successful transfer of data on TRNTD.
TRNTECRCGEN
Input
USERCLK
Transmit ECRC Generate (active-High). When asserted, this input
causes the TLP Digest to be recalculated (if present) or appended
(if not present). This input must be asserted along with packet SOF.
TRNTEOF
Input
USERCLK
Transmit End-of-Frame (active-High). This input signals the end of
a packet.
TRNTERRDROP
Output
USERCLK
Transmit Error Drop (active-High). When asserted, this output
indicates that the integrated block discarded a packet because of
a length violation or, when streaming, data was not presented on
consecutive clock cycles. Length violations include packets longer
than supported or packets whose payload does not match the
payload advertised in the TLP header length field.
TRNTERRFWD
Input
USERCLK
Transmit Error Forward (active-High). This input marks the current
packet in progress as error-poisoned. It can be asserted any time
between SOF and EOF, inclusive.
TRNTREM[1:0]
Input
USERCLK2
Transmit Data Remainder. Valid only if TRNTEOF, TRNTSRCRDY, and
TRNTDSTRDY are all asserted.
• 64-bit interface
Valid values are:
° TRNTREM = 1, packet data on TRNTD[63:0]
° TRNTREM = 0, packet data on TRNTD[63:32]
• 128-bit interface
TRNTREM[1:0] is used for the 128-bit interface. Valid values are:
° TRNTREM[1:0] = 11, packet data on TRNTD[127:0]
° TRNTREM[1:0] = 10, packet data on TRNTD[127:32]
° TRNTREM[1:0] = 01, packet data on TRNTD[127:64]
° TRNTREM[1:0] = 00, packet data on TRNTD[127:96]
TRNTSOF
Input
USERCLK
Transmit Start-of-Frame (active-High). When asserted, this input
indicates the start of a packet.
TRNTDSTRDY[3:0]
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Appendix D: PCIE_2_1 Port Descriptions
Table D-2:
Transaction Layer Interface Port Descriptions (Cont’d)
Port
Direction Clock Domain
Description
TRNTSRCDSC
Input
USERCLK
Transmit Source Discontinue (active-High). When asserted, this
input indicates that the user application is aborting the current
packet.
TRNTSRCRDY
Input
USERCLK
Transmit Source Ready (active-High). When asserted, this input
indicates that the user application is presenting valid data on
TRNTD.
TRNTSTR
Input
USERCLK
Transmit Streamed (active-High). When asserted, this input
indicates a packet is presented on consecutive clock cycles and
transmission on the link can begin before the entire packet has
been written to the integrated block.
Block RAM Interface
The Transmit (TX) and Receive (RX) buffers are implemented with block RAM. Table D-3
defines the TX buffer and RX buffer ports for the Block RAM interface.
Table D-3:
Block RAM Interface Port Descriptions
Port
Direction
Clock Domain
MIMRXRADDR[12:0]
Output
USERCLK
RX buffer read address
MIMRXRDATA[67:0]
Input
USERCLK
RX buffer read data
MIMRXREN
Output
USERCLK
RX buffer read enable
MIMRXWADDR[12:0]
Output
USERCLK
RX buffer write address
MIMRXWDATA[67:0]
Output
USERCLK
RX buffer write data
MIMRXWEN
Output
USERCLK
RX buffer write enable
MIMTXRADDR[12:0]
Output
USERCLK
TX buffer read address
MIMTXRDATA[68:0]
Input
USERCLK
TX buffer read data
MIMTXREN
Output
USERCLK
TX buffer read enable
MIMTXWADDR[12:0]
Output
USERCLK
TX buffer write address
MIMTXWDATA[68:0]
Output
USERCLK
TX buffer write data
MIMTXWEN
Output
USERCLK
TX buffer write enable
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Appendix D: PCIE_2_1 Port Descriptions
GTX Transceiver Interface
The GTX Transceiver interface consists of these signal groupings:
•
GTX Transceiver Ports
•
PIPE per Lane Ports
GTX Transceiver Ports
Table D-4 defines the transceiver ports within the GTX Transceiver interface.
Table D-4:
GTX Transceiver Port Descriptions
Direction
Clock
Domain
PLSELLNKRATE
Output
PIPECLK
This output reports the current link rate (driven by
a separate flip-flop to control the PIPECLK
BUFGMUX):
• 0b: 2.5 GB/s
• 1b: 5.0 GB/s
PLSELLNKWIDTH[1:0]
Output
PIPECLK
This output reports the current link width:
• 00b: x1
• 01b: x2
• 10b: x4
• 11b: x8
Port
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Appendix D: PCIE_2_1 Port Descriptions
Table D-4:
GTX Transceiver Port Descriptions (Cont’d)
Port
PLLTSSMSTATE[5:0]
Direction
Clock
Domain
Output
PIPECLK
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This output
• 000000b:
• 000001b:
• 000010b:
• 000011b:
• 000100b:
• 000101b:
• 000110b:
• 000111b:
• 001000b:
• 001001b:
• 001010b:
• 001011b:
• 001100b:
• 001101b:
• 001110b:
• 001111b:
• 010000b:
• 010001b:
• 010010b:
• 010011b:
• 010100b:
• 010101b:
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shows the current LTSSM state:
Det Quiet
Det Quiet Gen2
Det Active
Det Active Second
Pol Active
Pol config
Pol Comp Pre Send Eios
Pol Comp Pre Timeout
Pol Comp Send Pattern
Pol Comp Post Send Eios
Pol Comp Post Timeout
Cfg Lwidth St0
Cfg Lwidth St1
Cfg Lwidth Ac0
Cfg Lwidth Ac1
Cfg Lnum Wait
Cfg Lnum Acpt
Cfg Complete1
Cfg Complete2
Cfg Complete4
Cfg Complete8
Cfg Idle
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Appendix D: PCIE_2_1 Port Descriptions
Table D-4:
GTX Transceiver Port Descriptions (Cont’d)
Direction
Clock
Domain
PLLTSSMSTATE[5:0] (Cont’d)
Output
PIPECLK
This output shows the current LTSSM state:
• 010110b: L0
• 010111b: L1 Entry0
• 011000b: L1 Entry1
• 011001b: L1 Entry2
• 011010b: L1 Idle
• 011011b: L1 Exit
• 011100b: Rec Rcvrlock
• 011101b: Rec Rcvrcfg
• 011110b: Rec Speed 0
• 011111b: Rec Speed 1
• 100000b: Rec Idle
• 100001b: Hot Rst
• 100010b: Disabled Entry0
• 100011b: Disabled Entry1
• 100100b: Disabled Entry2
• 100101b: Disabled Idle
• 100110b: Dp Cfg Lwidth St0
• 100111b: Dp Cfg Lwidth St1
• 101000b: Dp Cfg Lwidth St2
• 101001b: Dp Cfg Lwidth Ac0
• 101010b: Dp Cfg Lwidth Ac1
• 101011b: Dp Cfg Lnum Wait
• 101100b: Dp Cfg Lnum Acpt
• 101101b: To 2 Detect
• 101110b: Lpbk Entry0
• 101111b: Lpbk Entry1
• 110000b: Lpbk Active0
• 110001b: Lpbk Exit0
• 110010b: Lpbk Exit1
• 110011b: Lpbkm Entry0
• 110100b - 111111b: Reserved
PLLANEREVERSALMODE[1:0]
Output
PIPECLK
This output shows the current Lane Reversal
mode:
• 00b: No reversal
• 01b: Lanes 1:0 reversed
• 10b: Lanes 3:0 reversed
• 11b: Lanes 7:0 reversed
PLPHYLNKUPN
Output
PIPECLK
This active-Low output indicates the Physical
Layer link up status.
Port
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Appendix D: PCIE_2_1 Port Descriptions
Table D-4:
GTX Transceiver Port Descriptions (Cont’d)
Direction
Clock
Domain
PLDIRECTEDLINKCHANGE[1:0]
Input
PIPECLK
This input directs the LTSSM to initiate a link width
and/or speed change:
• 00b: No change
• 01b: Force link width
• 10b: Force link speed
• 11b: Force link width and speed
(level-triggered)
PLDIRECTEDLINKWIDTH[1:0]
Input
PIPECLK
This input specifies the target link width for a
directed link change operation (it is only acted on
when DIRECTEDLINKCHANGE[0] is 1b):
• 00b: x1
• 01b: x2
• 10b: x4
• 11b: x8
PLDIRECTEDLINKSPEED
Input
PIPECLK
This input specifies the target link speed for a
directed link change operation (only acted on
when DIRECTEDLINKCHANGE[1] is 1b):
• 0b: 2.5 GB/s
• 1b: 5.0 GB/s
PLDIRECTEDLTSSMNEW[5:0]
Input
PIPECLK
Tie-off to 000000.
PLDIRECTEDLTSSMNEWVLD
Input
PIPECLK
Tie-off to 0.
PLDIRECTEDLTSSMSTALL
Input
PIPECLK
Tie-off to 0.
Output
PIPECLK
This output indicates that the directed link speed
change or directed link width change is done.
Input
PIPECLK
This input specifies link reliability or autonomous
for directed link change operation:
• 0b: Link reliability
• 1b: Autonomous
PLTXPMSTATE[2:0]
Output
PIPECLK
This output indicates the TX power management
state:
• 000b: TXNOTINL0S
• 001b: TXL0SENTRY
• 010b: TXL0SIDLE
• 011b: TXL0SFTS
• 100b - 111b: Reserved
PLRXPMSTATE[1:0]
Output
PIPECLK
This output indicates the RX power management
state:
• 00b: RXNOTINL0S
• 01b: RXL0SENTRY
• 10b: RXL0SIDLE
• 11b: RXL0SFTS
Port
PLDIRECTEDCHANGEDONE
PLDIRECTEDLINKAUTON
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Appendix D: PCIE_2_1 Port Descriptions
Table D-4:
GTX Transceiver Port Descriptions (Cont’d)
Direction
Clock
Domain
PLLINKUPCFGCAP
Output
PIPECLK
When this output is High, the link is upconfigure
capable (the link partner advertised upconfigure
capability [symbol 4, bit 6] in the TS2s while in the
Config.Complete state, and the device is
upconfigure capable).
PLLINKGEN2CAP
Output
PIPECLK
A High on this output indicates that the link is
5.0 GB/s capable (the link partner advertised a
5.0 GB/s data rate during the last transition from
Recovery.RcvrCfg or Config.Complete to the L0
state and the device is 5.0 GB/s capable).
PLLINKPARTNERGEN2SUPPORTED
Output
PIPECLK
This output is driven High if the link partner
supports a 5.0 GB/s data rate (advertised at least
after the 5.0 GB/s data rate was detected upon
exiting, while transitioning from Recovery.RcvrCfg
or Config.Complete to the L0 state).
PLINITIALLINKWIDTH[2:0]
Output
PIPECLK
This output specifies the initial negotiated link
width (when the first entry to Config.Idle from
detect was successfully completed).
• 000b: Link not trained yet
• 001b: x1
• 010b: x2
• 011b: x4
• 100b: x8
PLUPSTREAMPREFERDEEMPH
Input
PIPECLK
This input indicates the preferred de-emphasis of
an Endpoint. This input is used only when the
UPSTREAM_FACING attribute is set to TRUE.
• 0b: –6 dB
• 1b: –3.5 dB
PLDOWNSTREAMDEEMPHSOURCE
Input
PIPECLK
The downstream Root Port selects the
de-emphasis used on the link at 5.0 GB/s.
• 0b: Use Upstream Link Partner preferred
de-emphasis
• 1b: Use the Selectable De-Emphasis value from
the Link Control 2 Register (only used when the
UPSTREAM_FACING attribute is set to FALSE)
PIPETXRCVRDET
Output
PIPECLK
When asserted, this output either initiates a
receiver detection operation (in power state P1) or
begins loopback (in power state P0).
PIPETXRESET
Output
PIPECLK
When asserted, this output resets the PCS portion
of the GTX transceiver.
PIPETXRATE
Output
PIPECLK
This output controls the link signaling rate
(connects to the GTX transceiver):
• 0b: Use a 2.5 GB/s signaling rate
• 1b: Use a 5.0 GB/s signaling rate
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Table D-4:
GTX Transceiver Port Descriptions (Cont’d)
Direction
Clock
Domain
PIPETXDEEMPH
Output
PIPECLK
This output selects the transmitter de-emphasis:
• 0b: –6 dB de-emphasis
• 1b: –3.5 dB de-emphasis
PIPETXMARGIN[2:0]
Output
PIPECLK
This output selects the transmitter voltage levels:
• 000b: Normal operating range
• 001b: 1200 mV for full swing OR 400 - 700 mV
for half swing
• 010b: Required and vendor defined
• 011b: Required and vendor defined
• 100b: Required and 200 - 400 mV for full swing
OR 100 - 200 mV for half swing if the last value
or vendor defined
• 101b: Optional and 200 - 400 mV for full swing
OR 100 - 200 mV for half swing if the last value
OR vendor defined OR Reserved if no other
values supported
• 110b: Optional and 200 - 400 mV for full swing
OR 100 - 200 mV for half swing
• 111b: Optional and 200 - 400 mV for full swing
OR 100 - 200 mV for half swing if the last value
OR Reserved if no other values supported
Port
Description
PIPE per Lane Ports
Table D-5 defines the PIPE per Lane ports within the GTX Transceiver interface. There are
eight copies of the PIPE per lane ports, one for each lane (n = 0 to 7).
Table D-5:
PIPE per Lane Port Descriptions
Direction
Clock
Domain
PIPERXnCHANISALIGNED
Input
PIPECLK
When this input is asserted, the channel is properly
aligned with the master transceiver according to the
observed channel bonding sequences in the data stream.
PIPERXnCHARISK[1:0]
Input
PIPECLK
This input determines the control bit(s) for received data:
• 0b: Data byte
• 1b: Control byte
The lower bit corresponds to the lower byte of
PIPERXnDATA[15:0] while the upper bit describes the
upper byte.
PIPERXnDATA[15:0]
Input
PIPECLK
This input provides the received data.
PIPERXnELECIDLE
Input
PIPECLK
This asynchronous input indicates electrical idle on the
RX.
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Table D-5:
PIPE per Lane Port Descriptions (Cont’d)
Direction
Clock
Domain
Input
PIPECLK
This input indicates completion of GTX transceiver
functions, such as Power Management state transitions
and receiver detection on lane n. The completion is
indicated by a single cycle assertion of
PIPERXnPHYSTATUS.
Output
PIPECLK
When High, this output instructs the GTX transceiver to
invert polarity (on the RX differential pair).
PIPERXnSTATUS[2:0]
Input
PIPECLK
This input encodes the receiver status and error codes for
the received data stream and receiver detection on lane
n:
• 000b: Data received OK
• 001b: 1 SKP added
• 010b: 1 SKP removed
• 011b: Receiver Detected
• 100b: 8B/10B decode error
• 101b: Elastic Buffer overflow
• 110b: Elastic Buffer underflow
• 111b: Receive disparity error
PIPERXnVALID
Input
PIPECLK
This input indicates the presence of symbol lock and valid
data on PIPERX0DATA and PIPERX0CHARISK.
PIPETXnCHARISK[1:0]
Output
PIPECLK
This output defines the control bit(s) for transmit data:
• 0b: Data byte
• 1b: Control byte
The lower bit corresponds to the lower byte of
PIPETXnDATA[15:0] while the upper bit describes the
upper byte.
PIPETXnCOMPLIANCE
Output
PIPECLK
When asserted, this output forces the running disparity
to negative. It is used only when the compliance pattern
is transmitted.
PIPETXnDATA[15:0]
Output
PIPECLK
This output contains the transmit data.
PIPETXnELECIDLE
Output
PIPECLK
This output forces the transmit output to electrical idle in
all power states.
PIPETXnPOWERDOWN[1:0]
Output
PIPECLK
This output is the Power Management signal for the
transmitter for lane n:
• 00b: P0 (Normal operation)
• 01b: P0s (Low recovery time power-saving state)
• 10b: P1 (Longer recovery time power state)
• 11b: Reserved
Port
PIPERXnPHYSTATUS
PIPERXnPOLARITY
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Appendix D: PCIE_2_1 Port Descriptions
Configuration Management Interface
The Configuration Management Interface contains these signal groupings:
•
Management Interface Ports
•
Error Reporting Ports
•
Interrupt Generation and Status Ports
•
Root Port Specific Ports
•
Received Message TLP Status Ports
•
Power Management Ports
•
Received Configuration TLP Status Ports
•
Configuration-Specific Register Ports
•
Miscellaneous Configuration Management Ports
Management Interface Ports
Table D-6 defines the Management Interface ports within the Configuration Management
interface. These ports are used when reading and writing the Configuration Space Registers.
Table D-6:
Management Interface Port Descriptions
Direction
Clock
Domain
CFGMGMTBYTEENN[3:0]
Input
USERCLK
Management Access Byte Enable (active-Low). This
4-bit input provides the byte enables for the
configuration register access signal.
CFGMGMTDI[31:0]
Input
USERCLK
Management Data In. This 32-bit data input provides
write data to the configuration space inside the
integrated block.
CFGMGMTDO[31:0]
Output
USERCLK
Management Data Out. This 32-bit data output obtains
read data from the configuration space inside the
integrated block.
CFGMGMTDWADDR[9:0]
Input
USERCLK
Management DWORD Address. This 10-bit address
input provides a configuration register DWORD address
during configuration register accesses.
CFGMGMTRDENN
Input
USERCLK
Management Read Enable (active-Low). This input is the
read-enable for configuration register accesses.
Output
USERCLK
Management Read or Write Done (active-Low). The
read-write done signal indicates successful completion
of the user configuration register access operation. For
a user configuration register read operation, this signal
validates the value of the CFGMGMTDO[31:0] data bus.
Port
CFGMGMTRDWRDONEN
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Table D-6:
Management Interface Port Descriptions (Cont’d)
Direction
Clock
Domain
CFGMGMTWRENN
Input
USERCLK
Management Write Enable (active-Low). This input is
the write-enable for configuration register accesses.
CFGMGMTWRREADONLYN
Input
USERCLK
Management Write Read-only Bits (active-Low). When
asserted, this input indicates the current write should
treat a read-only (RO) bit as a read/write (RW) bit, not
including bits set by attributes, reserved bits, and bits
that reflect status. This permits you to change RO bits
(the bit remains RO for link-side accesses).
CFGMGMTWRRW1CASRWN
Input
USERCLK
Management Write RW1C Bit As RW (active-Low). When
asserted, this input indicates the current write should
treat any RW1C bit as a RW bit. An RW1C bit is cleared
by writing a 1 to it and can normally only be set by
internal integrated block conditions. The user uses this
signal to set the bit to 1.
Port
Description
Error Reporting Ports
Table D-7 defines the Error Reporting ports within the Configuration Management
interface.
Table D-7:
Error Reporting Port Descriptions
Direction
Clock
Domain
CFGERRACSN
Input
USERCLK
Configuration Error Access Control Services (ACS)
Violation (active-Low). The user application assert
this signal to report an ACS Violation.
CFGERRAERHEADERLOG[127:0]
Input
USERCLK
Configuration Error AER Header Log. This 128-bit
input accepts the header information for the AER
Header Log when an error is signaled.
Tie-off to 0.
Output
USERCLK
Not used.
CFGERRATOMICEGRESSBLOCKEDN
Input
USERCLK2
Configuration Error AtomicOp Egress Blocked
(active-Low). The user application asserts this
signal to report that an Atomic TLP was blocked.
CFGERRCORN
Input
USERCLK
Configuration Error Correctable Error (active-Low).
The user application asserts this signal to report a
Correctable Error.
CFGERRCPLABORTN
Input
USERCLK
Configuration Error Completion Aborted
(active-Low). The user application asserts this
signal to report a completion was aborted. This
signal is ignored if CFGERRCPLRDYN is deasserted.
Port
CFGERRAERHEADERLOGSETN
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Table D-7:
Error Reporting Port Descriptions (Cont’d)
Direction
Clock
Domain
Output
USERCLK
Configuration Error TLP Completion Header FIFO
Ready (active-Low). When this output is asserted,
the internal FIFO that buffers headers from
CFGERRTLPCPLHEADER[47:0] can accept entries.
When this output is deasserted, CFGERRURN and
CFGERRCPLABORTN are ignored by the integrated
block.
CFGERRCPLTIMEOUTN
Input
USERCLK
Configuration Error Completion Timeout
(active-Low). The user application asserts this
signal to report a completion timed out.
CFGERRCPLUNEXPECTN
Input
USERCLK
Configuration Error Completion Unexpected
(active-Low). The user application asserts this
signal to report that an unexpected completion
was received.
CFGERRECRCN
Input
USERCLK
ECRC Error Report (active-Low). The user
application asserts this signal to report an
end-to-end CRC (ECRC) error.
CFGERRINTERNALCORN
Input
USERCLK2
Configuration Error Corrected Internal
(active-Low). The user application asserts this
signal to report that an Internal error occurred and
was corrected.
CFGERRINTERNALUNCORN
Input
USERCLK2
Configuration Error Uncorrectable Internal
(active-Low). The user application asserts this
signal to report that an Uncorrectable Internal
error occurred.
CFGERRLOCKEDN
Input
USERCLK
Configuration Error Locked (active-Low). This
input is used to further qualify the CFGERRURN or
CFGERRCPLABORTN input signal. When this input
is asserted concurrently with one of those two
signals, it indicates that the transaction that
caused the error was an MRdLk transaction and
not an MRd. The integrated block generates a
CplLk instead of a Cpl if the appropriate response
is to send a Completion.
CFGERRMALFORMEDN
Input
USERCLK2
Configuration Error Malformed Error (active-Low).
The user application asserts this signal to report a
Malformed Error.
CFGERRMCBLOCKEDN
Input
USERCLK2
Configuration Error Multicast Blocked
(active-Low). The user application asserts this
signal to report that a Multicast TLP was blocked.
Port
CFGERRCPLRDYN
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Table D-7:
Error Reporting Port Descriptions (Cont’d)
Direction
Clock
Domain
CFGERRNORECOVERYN
Input
USERCLK2
Configuration Error Cannot Recover (active-Low).
This input further qualifies the
CFGERRPOISONEDN and CFGERRCPLTIMEOUTN
inputs. When this input is asserted concurrently
with one of these inputs, it indicates that the
transaction that caused these errors is not
recoverable. Thus, for a Completion Timeout, you
can elect not to re-attempt the Request. For a
received Poisoned TLP, you cannot continue
operation.
CFGERRPOISONEDN
Input
USERCLK2
Configuration Error Poisoned TLP (active-Low).
The user application asserts this signal to report
that a Poisoned TLP was received. This input is
only used if the DISABLE_RX_POISONED_RESP
attribute is 1.
CFGERRPOSTEDN
Input
USERCLK
Configuration Error Posted (active-Low). This
input is used to further qualify any of the CFGERR*
input signals. When this input is asserted
concurrently with one of the other signals, it
indicates that the transaction that caused the error
was a posted transaction.
CFGERRTLPCPLHEADER[47:0]
Input
USERCLK
Configuration Error TLP Completion Header. This
48-bit input accepts the header information when
an error is signaled. This information is required so
that the integrated block can issue a correct
completion, if required.
This information should be extracted from the
received error TLP and presented in the listed
format:
[47:41] Lower Address
[40:29] Byte Count
[28:26] TC
[25:24] Attr
[23:8] Requester ID
[7:0] Tag
CFGERRURN
Input
USERCLK
Configuration Error Unsupported Request
(active-Low). The user application asserts this
signal to report that an Unsupported Request (UR)
was received. This signal is ignored if
CFGERRCPLRDYN is deasserted.
Port
Description
Interrupt Generation and Status Ports
Table D-8 defines the Interrupt Generation and Status ports within the Configuration
Management interface.
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Table D-8:
Interrupt Generation and Status Port Descriptions
Direction
Clock
Domain
CFGINTERRUPTASSERTN
Input
USERCLK
Configuration Legacy Interrupt Assert/
Deassert Select. This input selects between
Assert and Deassert messages for Legacy
interrupts when CFGINTERRUPTN is
asserted. It is not used for MSI interrupts.
Value Message Type:
• 0b: Assert
• 1b: Deassert
CFGINTERRUPTDI[7:0]
Input
USERCLK
Configuration Interrupt Data In. For Message
Signaling Interrupts (MSI), this input
provides the portion of the Message Data
that the Endpoint must drive to indicate MSI
vector number, if Multi-Vector Interrupts are
enabled. The value indicated by
CFGINTERRUPTMMENABLE[2:0] determines
the number of lower-order bits of Message
Data that the Endpoint provides; the
remaining upper bits of
CFGINTERRUPTDI[7:0] are not used.
For Single-Vector Interrupts,
CFGINTERRUPTDI[7:0] is not used.
For Legacy Interrupt Messages (ASSERTINTX,
DEASSERTINTX), this input indicates which
message type is sent, where Value Legacy
Interrupt is:
• 00h: INTA
• 01h: INTB
• 02h: INTC
• 03h: INTD
CFGINTERRUPTDO[7:0]
Output
USERCLK
Configuration Interrupt Data Out. This
output is the value of the lowest eight bits of
the Message Data field in the Endpoint MSI
capability structure. This value is used in
conjunction with
CFGINTERRUPTMMENABLE[2:0] to drive
CFGINTERRUPTDI[7:0].
CFGINTERRUPTMMENABLE[2:0]
Output
USERCLK
Configuration Interrupt Multiple Message
Enabled. This output has the value of the
Multiple Message Enable field, where values
range from 000b to 101b. A value of 000b
indicates that single vector MSI is enabled.
Other values indicate the number of bits that
can be used for multi-vector MSI.
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Table D-8:
Interrupt Generation and Status Port Descriptions (Cont’d)
Direction
Clock
Domain
CFGINTERRUPTMSIENABLE
Output
USERCLK
Configuration Interrupt MSI Enabled.
• 0: Only Legacy (INTx) interrupts can be
sent
• 1: The Message Signaling Interrupt (MSI)
messaging is enabled
CFGINTERRUPTMSIXENABLE
Output
USERCLK
Configuration Interrupt MSIX Enabled. When
asserted, this output indicates that the
Message Signaling Interrupt (MSI-X)
messaging is enabled.
CFGINTERRUPTMSIXFM
Output
USERCLK
Configuration Interrupt MSIX Function Mask.
This output indicates the state of the
Function Mask bit in the MSI-X Message
Control field.
Input
USERCLK
Configuration Interrupt Request
(active-Low). When asserted, this input
causes the selected interrupt message type
to be transmitted by the integrated block.
The signal should be asserted until
CFGINTERRUPTRDYN is asserted.
CFGINTERRUPTRDYN
Output
USERCLK
Configuration Interrupt Ready (active-Low).
This output is the interrupt grant signal. The
simultaneous assertion of
CFGINTERRUPTRDYN and CFGINTERRUPTN
indicates that the integrated block has
successfully transmitted the requested
interrupt message.
CFGINTERRUPTSTATN
Input
USERCLK2
Configuration Interrupt Status. If the
INTERRUPT_STAT_AUTO attribute is set to 0:
• When this input is asserted, the Interrupt
Status bit (bit 3) in the Status register is
set.
• When this input is deasserted, the
Interrupt Status bit (bit 3) in the Status
register is unset.
Port
CFGINTERRUPTN
Description
Root Port Specific Ports
Table D-9 defines the Root Port Specific ports within the Configuration Management
interface.
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Appendix D: PCIE_2_1 Port Descriptions
Table D-9:
Root Port Specific Port Descriptions
Direction
Clock
Domain
CFGDSBUSNUMBER[7:0]
Input
USERCLK
Configuration Downstream Bus Number. This 8-bit
input provides the bus number portion of the
Requester ID (RID) of the Root Port, which is used in
TLPs generated inside the integrated block, such as
UR Completions and Power-Management messages.
It does not affect TLPs presented on the TRN
interface.
Tie-off to 0 for Endpoints.
CFGDSDEVICENUMBER[4:0]
Input
USERCLK
Configuration Downstream Device Number. This
5-bit input provides the device number portion of
the RID of the Root Port, which is used in TLPs
generated inside the integrated block, such as UR
Completions and Power-Management messages. It
does not affect TLPs presented on the TRN interface.
Tie-off to 0 for Endpoints.
CFGDSFUNCTIONNUMBER[2:0]
Input
USERCLK
Configuration Downstream Function Number. This
3-bit input provides the function number portion of
the RID of the Root Port. This is used in TLPs
generated inside the integrated block, such as UR
Completions and Power-Management messages. It
does not affect TLPs presented on the TRN interface.
Tie-off to 0 for Endpoints.
CFGPORTNUMBER[7:0]
Input
USERCLK
Configuration Root Port Number. This 8-bit input
provides the port number field in the Link
Capabilities Register.
Tie-off to 0 for Endpoints.
Port
Description
Received Message TLP Status Ports
Table D-10 defines the Received Message TLP Status ports within the Configuration
Management interface.
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Appendix D: PCIE_2_1 Port Descriptions
Table D-10:
Received Message TLP Status Port Descriptions
Direction
Clock
Domain
CFGMSGDATA[15:0]
Output
USERCLK
Message RID/Set Slot Data/Bus, Device,
Function Number.
Endpoint:
• If CFGMSGRECEIVED = 0, this output has the
captured Bus/Device/Function Number of an
Endpoint.
• If CFGMSGRECEIVED = 1 &
CFGMSGRECEIVEDSETSLOT
POWERLIMIT = 1, this output has the Power
Value and Scale fields.
• If CFGMSGRECEIVED = 1 &
CFGMSGRECEIVEDSETSLOT
POWERLIMIT = 0, this output has the RID of
the message.
Root Port:
• If any CFGMSGRECEIVED* signal pulses, this
output has the RID of the message.
• Otherwise, this output is undefined.
CFGMSGRECEIVED
Output
USERCLK
Configuration Received a Decodable Message.
This output is only asserted if a message was
received on the link. It is not asserted if an
upstream-moving message was generated
internally by a Root Port (although the
appropriate CFGMSGRECEIVEDERR* signal is
asserted).
CFGMSGRECEIVEDASSERTINTA
Output
USERCLK
This output pulses once for every Assert INTA
Message received on the link. The Requester ID
of the message appears on cfg_msg_data.
Not used for Endpoints.
CFGMSGRECEIVEDASSERTINTB
Output
USERCLK
This output pulses once for every Assert INTB
Message received on the link. The Requester ID
of the message appears on cfg_msg_data.
Not used for Endpoints.
CFGMSGRECEIVEDASSERTINTC
Output
USERCLK
This output pulses once for every Assert INTC
Message received on the link. The Requester ID
of the message appears on cfg_msg_data.
Not used for Endpoints.
CFGMSGRECEIVEDASSERTINTD
Output
USERCLK
This output pulses once for every Assert INTD
Message received on the link. The Requester ID
of the message appears on cfg_msg_data.
Not used for Endpoints.
CFGMSGRECEIVEDDEASSERTINTA
Output
USERCLK
This output pulses once for every Deassert
INTA Message received on the link. The
Requester ID of the message appears on
cfg_msg_data.
Not used for Endpoints.
Port
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Table D-10:
Received Message TLP Status Port Descriptions (Cont’d)
Direction
Clock
Domain
CFGMSGRECEIVEDDEASSERTINTB
Output
USERCLK
This output pulses once for every Deassert
INTB Message received on the link. The
Requester ID of the message appears on
cfg_msg_data.
Not used for Endpoints.
CFGMSGRECEIVEDDEASSERTINTC
Output
USERCLK
This output pulses once for every Deassert
INTC Message received on the link. The
Requester ID of the message appears on
cfg_msg_data.
Not used for Endpoints.
CFGMSGRECEIVEDDEASSERTINTD
Output
USERCLK
This output pulses once for every Deassert
INTD Message received on the link. The
Requester ID of the message appears on
cfg_msg_data.
Not used for Endpoints.
CFGMSGRECEIVEDERRCOR
Output
USERCLK
This output pulses once for every Correctable
Error Message received on the link or
generated internally by the Root Port (with the
intent of having the backend logic compose a
message upstream). The RID of the message
appears on cfg_msg_data.
Not used for Endpoints.
CFGMSGRECEIVEDERRFATAL
Output
USERCLK
This output pulses once for every Fatal Error
Message received on the link or generated
internally by a Downstream core (with the
intent of having the backend logic compose a
message upstream). The RID of the message
appears on cfg_msg_data.
Not used for Endpoints.
CFGMSGRECEIVEDERRNONFATAL
Output
USERCLK
This output pulses once for every Non-Fatal
Error Message received on the link or
generated internally by a Downstream core
(with the intent of having the backend logic
compose a message upstream). The RID of the
message appears on cfg_msg_data.
Not used for Endpoints.
CFGMSGRECEIVEDPMASNAK
Output
USERCLK
Received Power Management Active-State NAK
Message. This output pulses once for every PM
AS NAK Message received on the link. The RID
of the message appears on CFGMSGDATA.
CFGMSGRECEIVEDPMETO
Output
USERCLK
Received PM Turn Off Message. This output
pulses once for every PM Turn Off Message
received on the link. The RID of the message
appears on CFGMSGDATA.
Port
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Table D-10:
Received Message TLP Status Port Descriptions (Cont’d)
Direction
Clock
Domain
CFGMSGRECEIVEDPMETOACK
Output
USERCLK
This output pulses once for every PM Turn Off
Ack Message received on the link. The RID of
the message appears on cfg_msg_data.
Not used for Endpoints.
CFGMSGRECEIVEDPMPME
Output
USERCLK
This output pulses once for every Power
Management Event Message received on the
link. The RID of the message appears on
cfg_msg_data.
Not used for Endpoint.
CFGMSGRECEIVEDSETSLOTPOWERLIMIT
Output
USERCLK
Received Set Slot Power Limit Message. This
output pulses once for every Set Slot Power
Limit Message received on the link. The data of
this message (Value, Scale) appears on
CFGMSGDATA.
CFGMSGRECEIVEDUNLOCK
Output
USERCLK
Received Unlock Message. This output pulses
once for every Unlock Message received on the
link. The RID of the message appears on
CFGMSGDATA.
Port
Description
Power Management Ports
Table D-11 defines the Power Management ports within the Configuration Management
interface.
Table D-11:
Power Management Port Descriptions
Direction
Clock
Domain
CFGPMCSRPMEEN
Output
USERCLK2
PMCSR PME_En. This output sets the PME_En bit (bit 08) in
the PMCSR register.
CFGPMCSRPMESTATUS
Output
USERCLK2
PMCSR PME_Status. This output sets the PME_Status bit
(bit 15) in the PMCSR register.
CFGPMCSRPOWERSTATE
Output
USERCLK2
PMCSR PowerState[1:0]. This two-bit output determines
the current power state of the port function. The encoding
of this output is:
• 00b: D0
• 01b: D1
• 10b: D2
• 11b: D3hot
This output corresponds to the PowerState bits [01:00] of
the PMCSR register.
Port
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Table D-11:
Power Management Port Descriptions (Cont’d)
Direction
Clock
Domain
CFGPMFORCESTATE
Input
USERCLK2
Force PM State. When used in conjunction with
CFGPMFORCEENN, this input compels the Power
Management State Machine (PMSM) to attempt to stay in
or move toward the desired state. Drive the following value
on this bus to indicate the state:
• 00b: Move to or stay in L0 (or L0s/ASPM L1 if enabled)
• 01b: Move to or stay in PPM L1
• 10b: Move to or stay in ASPM L0s (only sampled if in
ASPM or L0)
• 11b: Move to or stay in ASPM L1 (only sampled if in
ASPM or L0)
CFGPMFORCESTATEENN
Input
USERCLK2
Force PM State Transition Enable (active-Low). When used
conjunction with CFGPMFORCESTATE, this input forces the
PM SM to attempt to stay in or move toward the desired
state. If the core attempts to move to a desired state, this
input must be held asserted until CFGPCIELINKSTATE
indicates the core is moving to that state.
CFGPMHALTASPML0SN
Input
USERCLK2
Halt ASPM L0s (active-Low). When asserted, this input
forces the core to avoid the ASPM L0s state. If the core is
already in the L0s state when this input is asserted, the
core returns to the L0 state. If CFGPMFORCESTATE
indicates the core should go to the L0s state, it overrides
this signal.
CFGPMHALTASPML1N
Input
USERCLK2
Halt ASPM L1 (active-Low).
• Endpoint
When asserted, this input forces the Endpoint core to
avoid the ASPM L1 state. If the core is already in the
ASPM L1 state when this input is asserted, the core
returns to the L0 state. If CFGPMFORCESTATE indicates
the core should go to the ASPM L1 state, it overrides this
signal.
• Root Port
When asserted, this input compels the Root Port core to
NAK an ASPM L1 Request, if the link partner requests to
go to the ASPM L1 state. (1)
CFGPMRCVASREQL1N
Output
USERCLK
Not used.
CFGPMRCVENTERL1N
Output
USERCLK
Not used.
CFGPMRCVENTERL23N
Output
USERCLK
This output pulses for every PM_Enter_L23 DLLP received.
PM_Enter_L23 DLLPs are received by a Root Port after it
sends a PME_Turn_Off Message. The Root Port
automatically responds; no action is required of the user.
Not used for Endpoint.
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Table D-11:
Power Management Port Descriptions (Cont’d)
Direction
Clock
Domain
CFGPMRCVREQACKN
Output
USERCLK
Received PMREQUESTACK DLLP (active-Low). When
asserted, this output indicates that a PMREQUESTACK
DLLP has been received by an Endpoint after it sends a
PMENTERL1, a PMENTERL23, or a PM AS Req L1. The
integrated block automatically responds; no action is
required of the user.
CFGPMSENDPMETON
Input
USERCLK
Asserting this active-Low input causes the Root Port to
send Turn Off Message. When the link partner responds
with a Turn Off Ack, this is reported on
CFGMSGRECEIVEDPMETOACK, and the final transition to
L3 Ready is reported on cfg_pcie_link_state.
Tie-off to 1 for Endpoint.
CFGPMTURNOFFOKN
Input
USERCLK
Configuration Turn off OK, PPM L3 (active-Low). The user
application can assert the active-Low power turn-off ready
signal to notify the Endpoint that it is safe for power to be
turned off. This input is sampled during or after the cycle
in which CFGMSGRECEIVEDPMETO pulses.
CFGPMWAKEN
Input
USERCLK
Send PMPME Message (active-Low). A one-clock cycle
assertion of this input signals the integrated block to send
a Power Management Wake Event (PMPME) Message TLP
to the upstream link partner.
Port
Description
Notes:
1. ASPM L1 is unsupported in the 7 Series Integrated Block for PCIe.
Received Configuration TLP Status Ports
Table D-12 defines the Received Configuration TLP Status ports within the Configuration
Management interface.
Table D-12:
Received Configuration TLP Status Port Descriptions (Configuration Management Interface)
Direction
Clock
Domain
CFGTRANSACTION
Output
USERCLK
Configuration Transaction Received. This output
pulses when a valid Config read or write is received in
the range of 0 - 7Fh (DWORD# 0 to 127).
CFGTRANSACTIONADDR[6:0]
Output
USERCLK
Configuration Transaction Address. This 7-bit output
contains the DWORD offset that was addressed
(0 - 7Fh). This output is valid only when
CFGTRANSACTION pulses.
CFGTRANSACTIONTYPE
Output
USERCLK
Configuration Transaction Type. This output indicates
the type of Configuration transaction when
CFGTRANSACTION pulses:
• 0: Read
• 1: Write
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Appendix D: PCIE_2_1 Port Descriptions
Configuration-Specific Register Ports
Table D-13 defines the Configuration-Specific Register ports within the Configuration
Management interface. These ports directly mirror the contents of commonly used registers
located within the PCI Express Configuration Space.
Table D-13:
Configuration-Specific Register Port Descriptions
Port
Clock
Direction Domain
Description
CFGAERROOTERRFATALRERRRECEIVED
Output
USERCLK2
Configuration AER, Fatal Error Messages
Received. This output indicates that an
ERR_FATAL Message was received.
CFGAERROOTERRFATALERRREPORTINGEN
Output
USERCLK2
Configuration AER, Fatal Error Reporting
Enable. This register bit enables the user
logic to generate interrupts for reported
Fatal Errors.
CFGAERROOTERRNONFATALRERRRECEIVED
Output
USERCLK2
Configuration AER, Non-Fatal Error
Messages Received.
AER_Root_Error_Status[5]. This register
bit indicates that an ERR_NFE Message
was received.
CFGAERROOTERRNONFATALERRREPORTINGEN
Output
USERCLK2
Configuration AER, Non-Fatal Error
Reporting Enable. This register bit
enables the user logic to generate
interrupts for reported Non-Fatal Errors.
Input
USERCLK2
Configuration AER, Interrupt Message
Number. This input drives the value on
AER Root Error Status Register[31:27]
(Interrupt Message Number).
Output
USERCLK2
Configuration Bridge Control, SERR
Enable. Bridge Ctrl[1]. When asserted,
this bit enables the forwarding of
Correctable, Non-fatal, and Fatal errors.
CFGAERINTERRUPTMSGNUM[4:0]
CFGBRIDGESERREN
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Table D-13:
Configuration-Specific Register Port Descriptions (Cont’d)
Direction
Clock
Domain
CFGCOMMANDBUSMASTERENABLE
Output
USERCLK
Configuration Command, Bus Master
Enable, Command[2]. The integrated
block takes no action based on this
setting; instead, you must.
• Endpoints:
When this output is asserted, the user
logic is allowed to issue Memory or I/
O Requests (including MSI/X
interrupts); otherwise, the user logic
must not issue those requests.
• Root Ports:
When this output is asserted, received
Memory or I/O Requests can be
forwarded upstream; otherwise these
requests must be handled as URs. For
Non-Posted Requests, a Completion
with UR completion status must be
returned.
CFGCOMMANDINTERRUPTDISABLE
Output
USERCLK
Configuration Command, Interrupt
Disable, Command[10]. When this
output is asserted, the integrated block
is prevented from asserting INTx
interrupts.
CFGCOMMANDIOENABLE
Output
USERCLK
Configuration Command, I/O Space
Enable, Command[0].
• Endpoints:
0: The integrated block filters these
accesses and responds with a UR.
1: Allows the device to receive I/O
Space accesses.
• Root Ports:
0: The user logic must not generate
TLPs downstream.
1: The integrated block takes no
action based on this setting.
CFGCOMMANDMEMENABLE
Output
USERCLK
Configuration Command, Memory
Space Enable, Command[1].
• Endpoints:
0: The integrated block filters these
accesses and responds with a UR.
1: Allows the device to receive
Memory Space accesses.
• Root Ports:
0: The user logic must not generate
TLPs downstream.
1: The integrated block takes no
action based on this setting.
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Table D-13:
Configuration-Specific Register Port Descriptions (Cont’d)
Direction
Clock
Domain
CFGCOMMANDSERREN
Output
USERCLK
Configuration Command, SERR Enable
(active-Low), Command[8].
When this output is asserted, reporting
of Non-fatal and Fatal errors is enabled.
If enabled, errors are reported either
through this bit or through the PCI
Express specific bits in the Device
Control Register. In addition, for a Root
Port application, this bit controls
transmission by the primary interface of
ERRNONFATAL and ERRFATAL Error
messages forwarded from the
secondary interface.
CFGDEVCONTROL2ARIFORWARDEN
Output
USERCLK2
Configuration Device Control 2, ARI
Forwarding Enable. When this register
bit is set, the Downstream Port disables
its traditional Device Number field
being zero enforcement when turning a
Type 1 Configuration Request into a
Type 0 Configuration Request. This
permits access to Extended Functions in
an ARI Device immediately below the
Port. The default for this bit is 0b. It
must be hardwired to 0b if the ARI
Forwarding Supported bit is 0b.
CFGDEVCONTROL2ATOMICEGRESSBLOCK
Output
USERCLK2
Configuration Device Control 2, Atomic
Egress Blocking. When this register bit is
set, AtomicOp Requests that target
going out this Egress Port must be
blocked. The default value of this bit is
0b.
CFGDEVCONTROL2ATOMICREQUESTEREN
Output
USERCLK2
Configuration Device Control 2, Atomic
Requester Enable. The Function is
allowed to initiate AtomicOp Requests
only if this bit and the Bus Master Enable
bit in the Command register are both
set. This bit is required to be RW if the
Endpoint or Root Port can initiate
AtomicOp Requests; otherwise it can be
hardwired to 0b. This bit does not serve
as a capability bit. This bit is permitted
to be RW even if no AtomicOp
Requester capabilities are supported by
the Endpoint or Root Port. The default
value of this bit is 0b.
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Table D-13:
Configuration-Specific Register Port Descriptions (Cont’d)
Direction
Clock
Domain
CFGDEVCONTROL2CPLTIMEOUTDIS
Output
USERCLK
Configuration Device Control 2,
Completion Timeout Disable,
DEVICECTRL2[4]. When asserted, this
output should cause the user
application to disable the Completion
Timeout counters.
CFGDEVCONTROL2CPLTIMEOUTVAL[3:0]
Output
USERCLK
Configuration Device Control 2,
Completion Timeout Value,
DEVICECTRL2[3:0]. This 4-bit output is
the time range that the user logic
should consider a Request's pending
Completion as a Completion Timeout.
The integrated block takes no action
based on this setting.
• 0000b: 50 µs to 50 ms (default)
• 0001b: 50 µs to 100 µs
• 0010b: 1 ms to 10 ms
• 0101b: 16 ms to 55 ms
• 0110b: 65 ms to 210 ms
• 1001b: 260 ms to 900 ms
• 1010b: 1 s to 3.5 s
• 1101b: 4 s to 13 s
• 1110b: 17 s to 64 s
CFGDEVCONTROL2IDOCPLEN
Output
USERCLK2
Configuration Device Control 2, IDO
Completion Enable. If this register bit is
set, the Function is permitted to set the
ID-Based Ordering (IDO) bit. A Function
can hardwire this bit to 0b if it never sets
the IDO attribute in Requests. The
default value of this bit is 0b.
CFGDEVCONTROL2IDOREQEN
Output
USERCLK2
Configuration Device Control 2, IDO
Request Enable. If this register bit is set,
the Function can set the IDO bit of
Requests it initiates. A Function can
hardwire this bit to 0b if it never sets the
IDO attribute in Requests. The default
value of this bit is 0b.
CFGDEVCONTROL2LTREN
Output
USERCLK2
Configuration Device Control 2, LTR
Mechanism Enable. If this register bit is
set, the Function can set the IDO bit. A
Function can hardwire this bit to 0b if it
never sets the IDO attribute in Requests.
The default value of this bit is 0b.
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Table D-13:
Configuration-Specific Register Port Descriptions (Cont’d)
Direction
Clock
Domain
CFGDEVCONTROL2TLPPREFIXBLOCK
Output
USERCLK2
Configuration Device Control 2,
End-to-End TLP Prefix Blocking.
Controls whether the routing function is
permitted to forward TLPs containing an
End-to-End TLP Prefix. Values are:
• 0b: Forwarding Enabled. The Function
can send TLPs with End-to-End TLP
Prefixes.
• 1b: Forwarding Blocked. The Function
is not permitted to send TLPs with
End-to-End TLP Prefixes.
Blocked TLPs are reported by the TLP
Prefix Blocked Error. The default value
for this bit is 0b.
CFGDEVCONTROLAUXPOWEREN
Output
USERCLK
Not used.
CFGDEVCONTROLCORRERRREPORTINGEN
Output
USERCLK
Configuration Device Control,
Correctable Error Reporting Enable,
DEVICECTRL[0]. This bit, in conjunction
with other bits, controls sending
ERRCOR messages. For a Root Port, the
reporting of correctable errors is
internal to the root; no external ERRCOR
message is generated.
CFGDEVCONTROLENABLERO
Output
USERCLK
Configuration Device Control, Enable
Relaxed Ordering, DEVICECTRL[4].
When this output is asserted, the user
logic is permitted to set the Relaxed
Ordering bit in the Attributes field of
transactions it initiates that do not
require strong write ordering.
CFGDEVCONTROLEXTTAGEN
Output
USERCLK
Configuration Device Control, Tag Field
Enable, DEVICECTRL[8]. When this
output is asserted, the user logic can
use an 8-bit Tag field as a Requester.
When this output is deasserted, the user
logic is restricted to a 5-bit Tag field.
The integrated block does not enforce
the number of Tag bits used, either in
outgoing request TLPs or incoming
Completions.
CFGDEVCONTROLFATALERRREPORTINGEN
Output
USERCLK
Configuration Device Control, Fatal
Error Reporting Enable, DEVICECTRL[2].
This bit, in conjunction with other bits,
controls sending ERRFATAL messages.
For a Root Port, the reporting of
correctable errors is internal to the root;
no external ERRFATAL message is
generated.
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Table D-13:
Configuration-Specific Register Port Descriptions (Cont’d)
Direction
Clock
Domain
CFGDEVCONTROLMAXPAYLOAD[2:0]
Output
USERCLK
Configuration Device Control,
MAXPAYLOADSIZE, DEVICECTRL[7:5].
This field sets the maximum TLP payload
size. As a Receiver, the user logic must
handle TLPs as large as the set value. As
a Transmitter, the user logic must not
generate TLPs exceeding the set value.
• 000b: 128-byte maximum payload
size
• 001b: 256-byte maximum payload
size
• 010b: 512-byte maximum payload
size
• 011b: 1024-byte maximum payload
size
CFGDEVCONTROLMAXREADREQ[2:0]
Output
USERCLK
Configuration Device Control,
MAXREADREQUESTSIZE,
DEVICECTRL[14:12]. This field sets the
maximum Read Request size for the user
logic as a Requester. The user logic must
not generate Read Requests with size
exceeding the set value.
• 000b: 128-byte maximum Read
Request size
• 001b: 256-byte maximum Read
Request size
• 010b: 512-byte maximum Read
Request size
• 011b: 1024-byte maximum Read
Request size
• 100b: 2048-byte maximum Read
Request size
• 101b: 4096-byte maximum Read
Request size
CFGDEVCONTROLNONFATALREPORTINGEN
Output
USERCLK
Configuration Device Control, Non-Fatal
Error Reporting Enable, DEVICECTRL[1].
This bit, in conjunction with other bits,
controls sending ERRNONFATAL
messages. For a Root Port, the reporting
of correctable errors is internal to the
root; no external ERRNONFATAL
message is generated.
CFGDEVCONTROLNOSNOOPEN
Output
USERCLK
Configuration Device Control, Enable
No Snoop, DEVICECTRL[11]. When this
output is asserted, the user logic is
permitted to set the No Snoop bit in
TLPs it initiates that do not require
hardware-enforced cache coherency.
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Table D-13:
Configuration-Specific Register Port Descriptions (Cont’d)
Direction
Clock
Domain
CFGDEVCONTROLPHANTOMEN
Output
USERCLK
Configuration Device Control, Phantom
Functions Enable, DEVICECTRL[9]. When
this output is asserted, the user logic
can use unclaimed Functions as
Phantom Functions to extend the
number of outstanding transaction
identifiers. If this output is deasserted,
the user logic is not allowed to use
Phantom Functions.
CFGDEVCONTROLURERRREPORTINGEN
Output
USERCLK
Configuration Device Control, UR
Reporting Enable, DEVICECTRL[3]. This
bit, in conjunction with other bits,
controls the signaling of URs by sending
Error messages.
CFGDEVSTATUSCORRERRDETECTED
Output
USERCLK
Configuration Device Status,
Correctable Error Detected,
DEVICESTATUS[0]. This output indicates
the status of correctable errors
detected. Errors are logged in this
register regardless of whether error
reporting is enabled or not in the Device
Control Register.
CFGDEVSTATUSFATALERRDETECTED
Output
USERCLK
Configuration Device Status, Fatal Error
Detected, DEVICESTATUS[2]. This output
indicates the status of Fatal errors
detected. Errors are logged in this
register regardless of whether error
reporting is enabled or not in the Device
Control Register.
CFGDEVSTATUSNONFATALERRDETECTED
Output
USERCLK
Configuration Device Status, Non-Fatal
Error Detected, DEVICESTATUS[1]. This
output indicates the status of Non-fatal
errors detected. Errors are logged in this
register regardless of whether error
reporting is enabled or not in the Device
Control Register.
CFGDEVSTATUSURDETECTED
Output
USERCLK
Configuration Device Status,
Unsupported Request Detected,
DEVICESTATUS[3]. This output indicates
that the integrated block received a UR.
Errors are logged in this register
regardless of whether error reporting is
enabled or not in the Device Control
Register.
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Table D-13:
Configuration-Specific Register Port Descriptions (Cont’d)
Direction
Clock
Domain
CFGLINKCONTROLASPMCONTROL[1:0]
Output
USERCLK
Configuration Link Control, ASPM
Control, LINKCTRL[1:0]. This 2-bit
output indicates the level of ASPM
supported, where:
• 00b: Disabled
• 01b: L0s Entry Enabled
• 10b: Not used
• 11b: Not used
CFGLINKCONTROLAUTOBANDWIDTHINTEN
Output
USERCLK
Configuration Link Control, Link
Autonomous Bandwidth Interrupt
Enable, LINKCTRL[11]. When asserted
active-Low, this bit enables the
generation of an interrupt to indicate
that the Link Autonomous Bandwidth
Status bit has been set. The core takes
no action based on the setting of this
bit; user logic must create the interrupt.
Not used for Endpoint.
CFGLINKCONTROLBANDWIDTHINTEN
Output
USERCLK
Configuration Link Control, Link
Bandwidth Management Interrupt
Enable, LINKCTRL[10]. When asserted,
active-Low, enables the generation of an
interrupt to indicate that the Link
Bandwidth Management Status bit has
been set. The core takes no action based
on the setting of this bit; user logic must
create the interrupt.
Not used for Endpoint.
CFGLINKCONTROLCLOCKPMEN
Output
USERCLK
Configuration Link Control, Enable
Clock Power Management, LINKCTRL[8].
For Endpoints that support a CLKREQ#
mechanism:
• 0b: Clock power management
disabled
• 1b: The device is permitted to use
CLKREQ#
The integrated block takes no action
based on the setting of this bit; this
function must be implemented in
external logic.
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Table D-13:
Configuration-Specific Register Port Descriptions (Cont’d)
Direction
Clock
Domain
CFGLINKCONTROLCOMMONCLOCK
Output
USERCLK
Configuration Link Control, Common
Clock Configuration, LINKCTRL[6].
When this output is asserted, this
component and the component at the
opposite end of this Link are operating
with a distributed common reference
clock. When this output is deasserted,
the components are operating with an
asynchronous reference clock.
CFGLINKCONTROLEXTENDEDSYNC
Output
USERCLK
Configuration Link Control, Extended
Synch, LINKCTRL[7]. When this output is
asserted, the transmission of additional
ordered sets is forced when exiting the
L0s state and when in the Recovery
state.
CFGLINKCONTROLHWAUTOWIDTHDIS
Output
USERCLK
Configuration Link Control, Hardware
Autonomous Width Disable,
LINKCTRL[9]. When this output is
asserted, the integrated block is
disabled from changing the Link width
for reasons other than attempting to
correct an unreliable Link operation by
reducing the Link width.
CFGLINKCONTROLLINKDISABLE
Output
USERCLK
Configuration Link Control, Link Disable,
LINKCTRL[4]. When this output is
asserted, indicates the Link is disabled
and directs the LTSSM to the Disabled
state.
Not used for Endpoint.
CFGLINKCONTROLRCB
Output
USERCLK
Configuration Link Control, RCB,
LINKCTRL[3]. This output indicates the
Read Completion Boundary value,
where:
• 0: 64B
• 1: 128B
CFGLINKCONTROLRETRAINLINK
Output
USERCLK
Configuration Link Control, Retrain Link,
LINKCTRL[5]. A write of 1b to this bit to
the Root Port Type 1 configuration
space initiates Link retraining by
directing the Physical Layer LTSSM to
the Recovery state. Configuration Reads
of this bit are always 0, but this signal
pulses for one cycle when a 1 is written
to it.
Not used for Endpoint.
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Table D-13:
Configuration-Specific Register Port Descriptions (Cont’d)
Direction
Clock
Domain
CFGLINKSTATUSAUTOBANDWIDTHSTATUS
Output
USERCLK
Configuration Link Status, Link
Autonomous Bandwidth Status,
LINKSTATUS[15]. Indicates the core has
autonomously changed Link speed or
width, without the Port transitioning
through DL_Down status, for reasons
other than to attempt to correct
unreliable Link operation. This bit must
be set if the Physical Layer reports a
speed or width change was initiated by
the Downstream component that was
indicated as an autonomous change.
Not used for Endpoint.
CFGLINKSTATUSBANDWIDTHSTATUS
Output
USERCLK
Configuration Link Status, Link
Bandwidth Management Status,
LINKSTATUS[14]. This output indicates
that either of the following has occurred
without the Port transitioning through
DL_Down status:
• A Link retraining has completed
following a write of 1b to the Retrain
Link bit. Note: This bit is Set following
any write of 1b to the Retrain Link bit,
including when the Link is in the
process of retraining for some other
reason.
• Hardware has changed Link speed or
width to attempt to correct unreliable
Link operation, either through an
LTSSM timeout or a higher level
process. This bit is set if the Physical
Layer reports a speed or width change
was initiated by the Downstream
component that was not indicated as
an autonomous change.
Not used for Endpoint.
CFGLINKSTATUSCURRENTSPEED[1:0]
Output
USERCLK
Configuration Link Status, Current Link
Speed, LINKSTATUS[1:0]. This field
indicates the negotiated Link speed of
the given PCI Express Link:
• 01b: 2.5 GB/s PCI Express Link
• 10b: 5.0 GB/s PCI Express Link
CFGLINKSTATUSDLLACTIVE
Output
USERCLK
Not used.
CFGLINKSTATUSLINKTRAINING
Output
USERCLK
Not used.
Port
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Table D-13:
Configuration-Specific Register Port Descriptions (Cont’d)
Direction
Clock
Domain
CFGLINKSTATUSNEGOTIATEDWIDTH[3:0]
Output
USERCLK
Configuration Link Status, Negotiated
Link Width, LINKSTATUS[7:4]. This
output indicates the negotiated width of
the given PCI Express Link (only widths
up to x8 are displayed).
• 0001b: x1
• 0010b: x2
• 0100b: x4
• 1000b: x8
CFGROOTCONTROLPMEINTEN
Output
USERCLK2
Configuration Root Control, PME
Interrupt Enable. This register bit
enables the user logic to generate an
Interrupt for received PME Messages.
CFGROOTCONTROLSYSERRCORRERREN
Output
USERCLK2
Configuration Root Control, System
Error on Correctable Error Enable. This
register bit enables the user logic to
generate a System Error for reported
Correctable Errors.
CFGROOTCONTROLSYSERRFATALERREN
Output
USERCLK2
Configuration Root Control, System
Error on Fatal Error Enable. This register
bit enables the user logic to generate a
System Error for reported Fatal Errors.
CFGROOTCONTROLSYSERRNONFATALERREN
Output
USERCLK2
Configuration Root Control, System
Error on Non-Fatal Error Enable. This
register bit enables the user logic to
generate a System Error for reported
Non-Fatal Errors.
CFGSLOTCONTROLELECTROMECHILCTLPULSE
Output
USERCLK
Not used.
Input
USERCLK
User Transaction Pending (active-Low).
When asserted, this input sets the
Transactions Pending bit in the Device
Status Register (DEVICESTATUS[5]).
Note: You must assert this input if the
user application has not received a
completion to a request.
Port
CFGTRNPENDINGN
Description
Miscellaneous Configuration Management Ports
Table D-14 defines the Miscellaneous Configuration Management ports within the
Configuration Management interface.
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Table D-14:
Miscellaneous Configuration Management Port Descriptions
Direction
Clock
Domain
CFGAERECRCCHECKEN
Output
USERCLK
Not used.
CFGAERECRCGENEN
Output
USERCLK
Not used.
CFGDEVID[15:0]
Input
USERCLK2
Configuration Device ID. This input indicates
the value to transfer to the PCI Capability
Structure Device ID field.
CFGDSN[63:0]
Input
USERCLK
Configuration Device Serial Number. This
64-bit input indicates the value that should
be transferred to the Device Serial Number
Capability. Bits [31:0] are transferred to the
first (Lower) DWORD (byte offset 0x4 of the
Capability), and bits [63:32] are transferred to
the second (Upper) DWORD (byte offset 0x8
of the Capability).
CFGFORCECOMMONCLOCKOFF
Input
USERCLK2
Force Common Clock Off. When asserted,
this input forces the core to behave as if
Common Clock was on (but does not set Link
Ctrl[7]).
CFGFORCEEXTENDEDSYNCON
Input
USERCLK2
Force Extended Synch On. When asserted,
this input forces the core to behave as if
Extended Synch was on (but does not set Link
Ctrl[7]).
CFGFORCEMPS[2:0]
Input
USERCLK2
Force Maximum Payload Size. When
ATTR_MPS_FORCE = 1, the core uses this
MPS value to check the payload size of
received TLPs and for replay/ACKNAK
time-outs, instead of using Device Ctrl[7:5]. It
does not change Device Ctrl[7:5].
CFGPCIECAPINTERRUPTMSGNUM[4:0]
Input
USERCLK2
Configuration PCIE Capabilities, Interrupt
Message Number. This input drives the value
on PCIe Capabilities Register[29:25]
(Interrupt Message Number).
Output
USERCLK
PCI Express Link State. This encoded bus
reports the PCIe Link State Information to the
user:
• 000b: L0 state
• 001b: PPM L1 state
• 010b: PPM L2/L3Ready state
• 011b: PMPME state
• 100b: In or transitioning to/from the ASPM
L0s state
• 101b: Transitioning to/from the PPM L1
state
• 110b: Transitioning to the PPM L2/L3Ready
state
• 111b: In or transitioning to/from the ASPM
L1 state
Port
CFGPCIELINKSTATE[2:0]
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Appendix D: PCIE_2_1 Port Descriptions
Table D-14:
Miscellaneous Configuration Management Port Descriptions (Cont’d)
Direction
Clock
Domain
CFGREVID[7:0]
Input
USERCLK2
Configuration Revision ID. This input
indicates the value to transfer to the PCI
Capability Structure Revision ID field.
CFGSUBSYSID[15:0]
Input
USERCLK2
Configuration Subsystem ID. This input
indicates the value to transfer to the Type 0
PCI Capability Structure Subsystem ID field.
CFGSUBSYSVENDID[15:0]
Input
USERCLK2
Configuration Subsystem Vendor ID. This
input indicates the value to transfer to the
Type 0 PCI Capability Structure Subsystem
Vendor ID field.
CFGCFGVCTCVCMAP[6:0]
Output
USERCLK2
Configuration VC Resource Control, TC/VC
Map. VC_Resource_Ctrl[7:1]. This output
indicates whether TCs 1–7 are valid for VC0.
The signal’s index is shifted by one with
respect to the register index (for example,
cfg_vc_tcvc_map[0] = VC_Resource_Ctrl[1]).
Input
USERCLK2
Configuration Device ID. This input indicates
the value to transfer to the PCI Capability
Structure Vendor ID field.
Port
CFGVENDID[15:0]
Description
Dynamic Reconfiguration Port Interface
Table D-15 describes the Dynamic Reconfiguration Port (DRP) ports.
Table D-15:
DRP Port Descriptions
Port
Direction
Clock Domain
Description
DRPCLK
Input
DRPADDR[8:0]
Input
DRPCLK
DRP address bus
DRPDI[15:0]
Input
DRPCLK
DRP input data bus
DRPDO[15:0]
Output
DRPCLK
DRP data out
Input
DRPCLK
DRP transaction enable
DRPRDY
Output
DRPCLK
DRP transaction done
DRPWE
Input
DRPCLK
DRP write enable
DRPEN
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Appendix D: PCIE_2_1 Port Descriptions
TL2 Interface Ports
The TL2 interface is unused but documented for completeness (see Table D-16).
Table D-16:
TL2 Interface Port Descriptions
Port
Direction
Clock Domain
LL2BADDLLPERR
Output
USERCLK
Not used.
LL2BADTLPERR
Output
USERCLK
Not used.
LL2LINKSTATUS
Output
USERCLK2
Not used.
LL2PROTOCOLERR
Output
USERCLK
Not used.
LL2RECEIVERERR
Output
USERCLK2
Not used.
LL2REPLAYROERR
Output
USERCLK
Not used.
LL2REPLAYTOERR
Output
USERCLK
Not used.
LL2SENDASREQL1
Input
USERCLK
Tie-off to 0.
LL2SENDENTERL1
Input
USERCLK
Tie-off to 0.
LL2SENDENTERL23
Input
USERCLK
Tie-off to 0.
LL2SENDPMACK
Input
USERCLK2
Tie-off to 0.
LL2SUSPENDNOW
Input
USERCLK
Tie-off to 0.
LL2SUSPENDOK
Output
USERCLK
Not used.
LL2TFCINIT1SEQ
Output
USERCLK
Not used.
LL2TFCINIT2SEQ
Output
USERCLK
Not used.
LL2TLPRCV
Input
USERCLK
Tie-off to 0.
LL2TXIDLE
Output
USERCLK2
Not used.
Input
USERCLK
Tie-off to 0.
PL2L0REQ
Output
USERCLK2
Not used.
PL2LINKUP
Output
USERCLK
Not used.
PL2RECEIVERERR
Output
USERCLK
Not used.
PL2RECOVERY
Output
USERCLK
Not used.
PL2RXELECIDLE
Output
USERCLK
Not used.
PL2RXPMSTATE[1:0]
Output
USERCLK2
Not used.
PL2SUSPENDOK
Output
USERCLK
Not used.
Input
USERCLK
Tie-off to 0.
TL2ASPMSUSPENDCREDITCHECKOK
Output
USERCLK
Not used.
TL2ASPMSUSPENDREQ
Output
USERCLK
Not used.
TL2ERRFCPE
Output
USERCLK2
Not used.
TL2ERRHDR[63:0]
Output
USERCLK2
Not used.
PL2DIRECTEDLSTATE[4:0]
TL2ASPMSUSPENDCREDITCHECK
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Appendix D: PCIE_2_1 Port Descriptions
Table D-16:
TL2 Interface Port Descriptions (Cont’d)
Port
Direction
Clock Domain
TL2ERRMALFORMED
Output
USERCLK2
Not used.
TL2ERRRXOVERFLOW
Output
USERCLK2
Not used.
TL2PPMSUSPENDOK
Output
USERCLK
Not used.
TL2PPMSUSPENDREQ
Input
USERCLK
Tie-off to 0.
TRNRDLLPDATA[31:0]
Output
USERCLK
Not used.
TRNRDLLPSRCRDY[1:0]
Output
USERCLK
Not used.
Input
USERCLK
Tie-off to 0.
TRNTDLLPDSTRDY
Output
USERCLK
Not used.
TRNTDLLPSRCRDY
Input
USERCLK
Tie-off to 0.
TRNTDLLPDATA[63:0]
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Appendix E
Additional Resources and Legal Notices
Xilinx Resources
For support resources such as Answers, Documentation, Downloads, and Forums, see Xilinx
Support.
References
This section provides supplemental material useful with this product guide.
1. AMBA AXI4-Stream Protocol Specification
2. PCI-SIG® Specifications
3. Intel Developer Forum For PCI Express Architecture
4. Virtex-7 FPGA Gen3 Integrated Block for PCI Express Product Guide (PG023)
5. Kintex-7 FPGAs Data Sheet: DC and AC Switching Characteristics (DS182)
6. Virtex-7 FPGAs Data Sheet: DC and Switching Characteristics (DS183)
7. 7 Series FPGAs Configuration User Guide (UG470)
8. Zynq-7000 All Programmable SoC Technical Reference Manual (UG585)
9. Zynq-7000 All Programmable SoC Software Developers Guide (UG821)
10. 7 Series FPGAs SelectIO Resources User Guide (UG471)
11. 7 Series FPGAs Clocking Resources User Guide (UG472)
12. 7 Series FPGAs GTX/GTH Transceivers User Guide (UG476)
13. 7 Series FPGAs GTP Transceivers User Guide (UG482)
14. Vivado Design Suite User Guide: Getting Started (UG910)
15. Vivado Design Suite User Guide: Design with IP (UG896)
16. Vivado Design Suite User Guide: Logic Simulation (UG900)
17. Vivado Design Suite User Guide: Programming and Debugging (UG908)
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Appendix E: Additional Resources and Legal Notices
18. ISE to Vivado Design Suite Migration Methodology Guide (UG911)
19. Vivado Design Suite User Guide: Designing IP Subsystems using IP Integrator (UG994)
20. Vivado Design Suite Tcl Command Reference Guide (UG835)
21. PIPE Mode Simulation Using Integrated Endpoint PCI Express Block in Gen2 x8
Configurations Application Note (XAPP1184)
22. ATX 12V Power Supply Design Guide
Revision History
The following table shows the revision history for this document.
Date
Version
Revision
07/02/2015
3.1
• Corrected the resource utilization data.
06/24/2015
3.1
• Added encrypted bitstream support details to the Tandem Configuration
section.
• Added qZyng-7000 device and package support in the Recommended
Integrated Block for PCIe table.
• Added significant detail to the Relocating the Integrated Block Core
section.
• Clarified that the Enable External PIPE Interface option (PIPE Mode
Simulations) is tested only with the BFM from Avery Design Systems.
• Added a new test to the Root Port Model Provided Tests table (Test Benches
chapter).
• Changed Vivado Lab Edition to Vivado Design Suite Debug Feature.
04/01/2015
3.1
• Updated BUFG usage values of the standalone PCIe core.
• Updated speed grade and link width support for the supported
Zynq®-7000 devices in the Core Configurations table in the Minimum
Device Requirements section.
• Added a note regarding supported optional frequency clock frequencies
for Artix-7 devices and certain speed grades.
• Added clarifying note regarding the core parameters in the top-level file
and core top module in the example designs.
• Added the pipe_txinhibit port.
• Changed Vivado lab tools to Vivado Lab Edition.
11/19/2014
3.0
•
•
•
•
•
10/01/2014
3.0
• Correction to valid values for m_axis_rx_tuser[21:17] receiver interface
signal.
• Updated the tandem configuration information.
Added new Artix and Zynq device support.
Updated the tandem configuration information.
Correction made to the AER_CAP_VERSION[3:0] value.
Clarification made to the PIPE Mode Simulations parameter description.
Added support for Cadence Incisive Enterprise Simulator (IES) and
Synopsys Verilog Compiler Simulator (VCS).
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Appendix E: Additional Resources and Legal Notices
Date
Version
Revision
06/04/2014
3.0
• Added new device support.
• Updated tandem configuration information.
04/02/2014
3.0
• Updated device and package information.
12/18/2013
3.0
•
•
•
•
•
Updated for core v3.0.
Updated integrated blocks table for Artix-7 in Product Specification.
Updated logic sharing information in Designing with the Core.
Updated supported core pinouts in Constraining the Core.
Updated parameter and port information in Migrating and Updating
appendix.
10/02/2013
2.2
•
•
•
•
Updated for core v2.2.
Added Vivado IP integrator support.
Added BUFG resource utilization numbers.
Added information about the Shared Logic feature, and the new Share
Logic and Core Interface Parameters options in the Vivado IDE.
Updated the Tandem Configuration section.
Added Simulation, Synthesis and Implementation, and Test Bench chapters.
Reorganized content: moved test bench information from Example Design
chapter to Test Bench chapter, and moved core simulation content into
Simulation chapter.
Updated the example design content.
Added the Transceiver Control and Status Port section to Debugging
appendix.
Added core parameter and port changes to Migrating and Upgrading
appendix.
•
•
•
•
•
•
06/19/2013
2.1
•
•
•
•
Updated for core v2.1.
Major updates to the Tandem Configuration section in Chapter 3.
Updated the Directory and File Contents section in Chapter 5.
Added simulation instructions in Chapter 5.
03/20/2013
2.0
• Updated for core v2.0 and for Vivado Design Suite-only support.
• Added the PIPE_MMCM_RST_N clocking interface signal.
• Updated Clocking in Chapter 3.
12/18/2012
1.2
• Updated for core v1.8, ISE Design Suite 14.4, and Vivado Design Suite
2012.4.
• Updated the available integrated block for PCIe: Table 2-5 and Table 5-1.
• Major revisions made to Clocking in Chapter 3.
• Updated Chapter 4, Customizing and Generating the Core.
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Appendix E: Additional Resources and Legal Notices
Date
Version
Revision
10/16/2012
1.1
• Updated core to v1.7, ISE Design Suite to 14.3, and Vivado Design Suite to
2012.3.
• Added Zynq®-7000 device family support.
• Removed XC7V1500T, and XC7A350T.
• Added new sections to Chapter 3.
• New screenshots and descriptions in Chapter 4.
• Added Chapter 6 and Chapter 15.
07/25/2012
1.0
Initial Xilinx release. This document includes support for Vivado Design Suite
v2012.2 and ISE Design Suite v14.2 for core version 1.6. This document
replaces UG477, 7 Series FPGAs Integrated Block for PCI Express User Guide
and DS821, LogiCORE IP 7 Series FPGAs Integrated Block for PCI Express Data
Sheet.
Please Read: Important Legal Notices
The information disclosed to you hereunder (the "Materials") is provided solely for the selection and use of Xilinx products. To the
maximum extent permitted by applicable law: (1) Materials are made available "AS IS" and with all faults, Xilinx hereby DISCLAIMS
ALL WARRANTIES AND CONDITIONS, EXPRESS, IMPLIED, OR STATUTORY, INCLUDING BUT NOT LIMITED TO WARRANTIES OF
MERCHANTABILITY, NON-INFRINGEMENT, OR FITNESS FOR ANY PARTICULAR PURPOSE; and (2) Xilinx shall not be liable (whether
in contract or tort, including negligence, or under any other theory of liability) for any loss or damage of any kind or nature related
to, arising under, or in connection with, the Materials (including your use of the Materials), including for any direct, indirect, special,
incidental, or consequential loss or damage (including loss of data, profits, goodwill, or any type of loss or damage suffered as a
result of any action brought by a third party) even if such damage or loss was reasonably foreseeable or Xilinx had been advised
of the possibility of the same. Xilinx assumes no obligation to correct any errors contained in the Materials or to notify you of
updates to the Materials or to product specifications. You may not reproduce, modify, distribute, or publicly display the Materials
without prior written consent. Certain products are subject to the terms and conditions of Xilinx's limited warranty, please refer to
Xilinx's Terms of Sale which can be viewed at http://www.xilinx.com/legal.htm#tos; IP cores may be subject to warranty and support
terms contained in a license issued to you by Xilinx. Xilinx products are not designed or intended to be fail-safe or for use in any
application requiring fail-safe performance; you assume sole risk and liability for use of Xilinx products in such critical applications,
please refer to Xilinx's Terms of Sale which can be viewed at http://www.xilinx.com/legal.htm#tos.
© Copyright 2012–2015 Xilinx, Inc. Xilinx, the Xilinx logo, Artix, ISE, Kintex, Spartan, Virtex, Vivado, Zynq, and other designated
brands included herein are trademarks of Xilinx in the United States and other countries. PCI, PCIe and PCI Express are trademarks
of PCI-SIG and used under license. All other trademarks are the property of their respective owners.
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