GTS AXI Streaming Intel® FPGA IP for PCI Express* User Guide

ID 813754
Date 11/04/2024
Public
Document Table of Contents

6.5.1. Configuration Extension Bus Request Interface

The GTS AXI Streaming IP sends configuration read and configuration write requests using this interface. The interface follows the AXI4-Stream interface protocol with the ready valid handshake. The interface supports a maximum of one outstanding read request.

Table 65.  Configuration Extension Bus Request Interfacen = 0 or 1, p0 = port 0, and p1 = port 1
Note: Port 1 is only available in D-Series FPGAs
EP = Endpoint, RP = Root Port, BP = TLP Bypass
Signal Name Direction Port Mode Clock Domain Description
p<n>_ss_app_st_cebreq_tvalid Output EP p<n>_axi_lite_clk

When asserted, indicates a valid Configuration Extension access cycle. It is deasserted when p<n>_app_ss_st_cebreq_tready is asserted.

p<n>_app_ss_st_cebreq_tready Input EP p<n>_axi_lite_clk

Application asserts this signal for one clock to acknowledge p<n>_ss_app_st_cebreq_tvalid is seen by responder.

p<n>_ss_app_st_cebreq_tdata[67:0]

Output EP p<n>_axi_lite_clk
  • Bit[9:0]: DWORD address of register being accessed.
  • Bit[14:10]: Reserved.
  • Bit[17:15]: The PF number of register access (PF[2:0]).
  • Bit[28:18]: Indicates child VF number of parent PF indicated by p<n>_ss_app_st_cebreq_tdata[17:15].
  • Bit[29]: Indicates access is for virtual function implemented in slot's physical function.
  • Bit[61:30]: Write data for write access.
  • Bit[65:62]: Indicates the configuration register access type, read or write. For writes, indicates the byte enables: The following encodings are defined:
    • 4'b0000: Read
    • 4'b0001: Write byte 0
    • 4'b0010: Write byte 1
    • 4'b0100: Write byte 2
    • 4'b1000: Write byte 3
    • 4'b1111: Write all bytes
    Combinations of byte enables, for example, 4'b0101 are also valid.
  • Bit[67:66]: Reserved.
The following below shows timing diagram for write command; the first command sends write for all four bytes of register located at address 4. The p<n>_ss_app_st_cebreq_tdata[29] signal is low which indicates that the access is for a physical function. The second command sends write for byte 3 and byte 2 for register located at address 8. The p<n>_ss_app_st_cebreq_tdata[29] signal is high which indicates that the access is for a virtual function.
Figure 52. Timing Diagram for Configuration Extension Bus Request Interface