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132 21555 Non-Transparent PCI-to-PCI Bridge User Manual
List of Registers
3 Prefetchable R
Indicates if this space is prefetchable.
• When a 0, do not use prefetching when reading the 21555 registers.
11:4 — R Returns zero.
31:12
Base
Address
R/W
Indicate to configuration software the size of the requested memory address
range and set the base address of the range. The bits are mappable, and
indicates that the 21555 is requesting a 4Kb memory space.
a. The Secondary CSR Memory BARs map the 21555 registers into secondary bus memory space.
Table 36. Primary and Secondary CSR I/O Bars
a
a. The Primary and Secondary CSR I/O BARs map the 21555 registers into primary and secondary
I/O space, respectively.
Bit Name R/W Description
0 Space Indicator R
Indicates the type of address space that is requested.
When a one (1), I/O space is requested.
7:1 Reserved R Returns 0.
31:8 Base Address R/W
Indicates to configuration software the size of the requested I/O
address range and set the base address of the range. The bits are
mappable, and indicates that the 21555 is requesting a 256 byte I/O
space.
Table 35. Secondary CSR Memory BARs
a
(Sheet 2 of 2)
• Primary byte offset: 53:50h
• Secondary byte offset: 13:10h
Bit Name R/W Description
Offsets Primary CSR I/O BAR Secondary CSR I/O BAR
Primary byte 17:14h 57:54h
Secondary byte 57:54h 17:14h