XIO2000A_08 Datasheet, PDF (126/159 Pages) TEXAS ADVANCED OPTOELECTRONIC SOLUTIONS – PCI Express to PCI Bus Translation Bridge

PCI Express Extended Configuration Space
5.26 VC Resource Status Register (VC1)
The VC resource status register allows software to monitor the status of the port arbitration table for this VC.
See Table 5−22 for a complete description of the register contents.
PCI Express extended register offset:
Register type:
Default value:
176h
Read-only
0000h
BIT NUMBER 15 14 13 12 11 10 9
8
7
6
5
4
3
2
1
0
RESET STATE 0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
Table 5−22. VC Resource Status Register (VC1) Description
BIT
FIELD NAME ACCESS
DESCRIPTION
15:2
RSVD
R
Reserved. Returns 00 0000 0000 0000b when read.
1
VC_PENDING
RU
VC negotiation pending. This bit is asserted when VC negotiation is in progress following a
request by software to enable the second VC.
Port arbitration table status. This bit is automatically set by hardware when any modification is
0
PORT_TABLE
_STATUS
RU
made to the port arbitration table entries for this VC within the extended configuration space.
This bit is cleared by hardware after software has requested a port arbitration table refresh and
the refresh has been completed.
5.27 VC Arbitration Table
The VC arbitration table is provided to allow software to define round-robin weighting for traffic targeting the
PCI Express port. The table is divided into 32 phases. See Table 5−24 for a complete description of the register
contents.
PCI Express extended register offset:
Register type:
Default value:
180h – 18Ch
Read-only, Read/Write
0000 0000h
Phase 7
Phase 15
Phase 23
Phase 31
Phase 6
Phase 14
Phase 22
Phase 30
Phase 5
Phase 13
Phase 21
Phase 29
Table 5−23. VC Arbitration Table
REGISTER FORMAT
Phase 4
Phase 3
Phase 2
Phase 12
Phase 11
Phase 10
Phase 20
Phase 19
Phase 18
Phase 28
Phase 27
Phase 26
Phase 1
Phase 9
Phase 17
Phase 25
Phase 0
Phase 8
Phase 16
Phase 24
OFFSET
180h
184h
188h
18Ch
Each phase consists of a four-bit field as indicated below.
BIT NUMBER
3
2
1
0
RESET STATE 0
0
0
0
Table 5−24. VC Arbitration Table Entry Description
BIT FIELD NAME ACCESS
DESCRIPTION
3
RSVD
R
Reserved. Returns 0b when read.
2:0
VC_ARB_ID
Virtual channel ID. This 3-bit field is used by software to identify the VC ID that must be allocated
RW this slot of arbitration bandwidth depending upon the VC arbitration scheme enabled. The default
value for this field is 000b.
116 SCPS155C
April 2007 Revised October 2008