XIO2000AI TAOS [TEXAS ADVANCED OPTOELECTRONIC SOLUTIONS], XIO2000AI Datasheet - Page 119

• Manufacturer Part Number: XIO2000AI
• Description: PCI Express to PCI Bus Translation Bridge
• Manufacturer: TAOS [TEXAS ADVANCED OPTOELECTRONIC SOLUTIONS]

5.16 Next Capability Offset/Capability Version Register
5.17 Port VC Capability Register 1
April 2007 Revised October 2008
31:12
11:10
BIT
9:8
6:4
2:0
7
3
This read-only register returns the value 000h to indicate that this extended capability block represents the
end of the linked list of extended capability structures. The four least significant bits identify the revision of the
current capability block as 1h.
The first port VC capability register provides information to software regarding the VC capabilities support by
the bridge. See Table 5−13 for a complete description of the register contents.
RESET STATE
RESET STATE
RESET STATE
LOW_PRIORITY_COUNT
BIT NUMBER
BIT NUMBER
BIT NUMBER
PCI Express extended register offset:
Register type:
Default value:
PCI Express extended register offset:
Register type:
Default value:
PORT_TABLE_SIZE
EXT_VC_COUNT
FIELD NAME
REF_CLK
RSVD
RSVD
RSVD
15
31
15
0
0
0
Table 5−13. Port VC Capability Register 1 Description
14
30
14
0
0
0
ACCESS
RU
R
R
R
R
R
R
13
29
13
0
0
0
12
28
12
Reserved. Returns 00000h when read.
Port arbitration table entry size. This read-only field returns a value of 10b to indicate
that the field size within the port arbitration table is four bits. This is necessary to allow
as many as six secondary PCI bus masters.
Reference clock. This read-only field returns a value of 00b to indicate than an internal
100-ns timer is used for time-based, WRR port arbitration.
Reserved. Returns 0b when read.
Low priority extended VC count. When bit 25 (STRICT_PRIORITY_EN) in the general
control register (offset D4h, see Section 4.65) is 0b, the default
LOW_PRIORITY_COUNT is 001b. When STRICT_PRIORITY_EN is 1b, the default
LOW_PRIORITY_COUNT is 000b. When STRICT_PRIORITY_EN is set, strict priority
VC arbitration is used and the extended VC always receives priority over VC0 at the
PCI Express port.
Reserved. Returns 0b when read.
Extended VC count. This read-only field returns a value of 001b to indicate support for
one extended VC.
0
0
0
27
11
11
0
0
1
10
26
10
0
0
0
152h
Read-only
154h
Read-only
0000 08X1h
0001h
25
9
0
0
9
0
24
8
0
0
8
0
23
7
0
0
7
0
DESCRIPTION
PCI Express Extended Configuration Space
22
6
0
0
6
0
21
5
0
0
5
0
20
4
0
0
4
x
19
3
0
0
3
0
SCPS155C
18
2
0
0
2
0
17
1
0
0
1
0
16
0
1
0
0
1
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