XIO3130
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SLLS693F–MAY 2007–REVISED JANUARY 2010
4.3.15 I/O Base Register
This read/write register specifies the lower limit of the I/O addresses that the XIO3130 downstream port
forwards downstream.
PCI register offset:
Register type:
1Ch
Read/Write; Read Only
01h
Default value:
BIT NUMBER
RESET STATE
7
6
5
4
3
2
1
0
0
0
0
0
0
0
0
1
Table 4-55. Bit Descriptions – I/O Base Register
BIT
FIELD NAME
IOBASE
ACCESS
DESCRIPTION
I/O base. This field defines the bottom address of the I/O address range that is used to
determine when to forward I/O transactions from one interface to the other. These bits
correspond to address bits [15:12] in the I/O address. The lower 12 bits are assumed to be 0.
The 16 bits that correspond to address bits [31:16] of the I/O address are defined in the I/O
Base Upper 16 Bits register.
7:4
3:0
rw
r
IOTYPE
I/O type. This field is read-only 01h, which indicates 32 bit I/O addressing support.
4.3.16 I/O Limit Register
This read/write register specifies the upper limit of the I/O addresses that the XIO3130 downstream port
forwards downstream.
PCI register offset:
Register type:
1Dh
Read/Write; Read Only
01h
Default value:
BIT NUMBER
RESET STATE
7
6
5
4
3
2
1
0
0
0
0
0
0
0
0
1
Table 4-56. Bit Descriptions – I/O Limit Register
BIT
FIELD NAME
IOLIMIT
ACCESS
DESCRIPTION
I/O limit. This field defines the top address of the I/O address range that is used to determine
when to forward I/O transactions from one interface to the other. These bits correspond to
address bits [15:12] in the I/O address. The lower 12 bits are assumed to be FFFh. The 16
bits that correspond to address bits [31:16] of the I/O address are defined in the I/O Limit
Upper 16 Bits register.
7:4
3:0
rw
r
IOTYPE
I/O type. This field is read-only 01h, which indicates 32-bit I/O addressing support.
4.3.17 Secondary Status Register
The Secondary Status register provides information about the downstream port PCI Express interface.
PCI register offset:
Register type:
1Eh
Read Only; Clear by a Write of One; Hardware Update
0000h
Default value:
BIT NUMBER
RESET STATE
15
14
13
12
11
10
9
8
7
6
5
4
3
2
1
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
Copyright © 2007–2010, Texas Instruments Incorporated
XIO3130 Configuration Register Space
93
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