TPH Requester Capability Register @0x278

This is a read-only register that specifies the capabilities associated with the implementation of the TPH in the device. All the fields in this register, except the reserved ones, can be modified from the local management bus.

Table 1. i_TPH_req_cap_reg
Bits SW Name Description Reset
0 R No ST Mode Supported [NSM] When set to 1, indicates that this Function supports the 'No ST Mode' for the generation of TPH Steering Tags. In the No ST Mode, the device must use a Steering Tag value of 0 for all requests. This bit is hardwired to 1 as all TPH Requesters are required to support the No ST Mode of operation. 0x1
1 R Interrupt Vector Mode Supported [IVMS] A setting of 1 indicates that the Function supports the Interrupt Vector Mode for TPH Steering Tag generation. In the Interrupt Vector Mode, Steering Tags are attached to MSI/MSI-X interrupt requests. The Steering Tag for each interrupt request is selected by the MSI/MSI-X interrupt vector number. This bit is set to 1 by default, but can be modified from the local management bus. 0x1
2 R Device- Specific Mode Supported [DSMS] A setting of 1 indicates that the Function supports the Device- Specific Mode for TPH Steering Tag generation. In this mode, the Steering Tags are supplied by the client for each request through the HAL master interface. The client typically chooses the Steering Tag values from the ST Table, but is not required to do so. This bit is set to 1 by default, but can be modified from the local management bus. 0x1
7:3 R Reserved [R0] Reserved 0x0
8 R Extended TPH Requester Supported [ERS] When set to 1, indicates that the Function is capable of generating requests with a TPH TLP Prefix. 0x0
10:9 R ST Table Location [STL] The setting of this field indicates if a Steering Tag Table is implemented for this Function and its location if present.
  • 00 = ST Table not present
  • 01 = ST Table in the TPH Requester Capability Structure
  • 10 = ST values stored in the MSI-X Table in client RAM
  • 11 = Reserved
This field can be modified from the local management bus.		 0x1
15:11 R Reserved [R1] Reserved 0x0
26:16 R ST Table Size [STS] Specifies the number of entries in the Steering Tag Table (0 = 1 entry, 1 = 2 entries, and so on). Max limit is 64 entries when the ST Table is located in the TPH Requester Capability Structure, and 2048 entries when located in the MSI-X table. Each entry is 16 bits long. This field can be modified from the local management bus. 11'd7
31:27 R Reserved [R2] Reserved 0x0