Intel
®
81341 and 81342 I/O Processors
December 2007
Developer’s Manual
Order Number: 315037-002US
557
System Controller (SC) and Internal Bus Bridge—Intel
®
81341 and 81342
6.5.6
Bridge Window Base Address Register — BWBAR
The Bridge Base Address Register (BWBAR) defines the block of memory addresses
where the Bridge Memory Window begins. The BWBAR is used in conjunction with the
BWLR to form a memory window that is used by the Bridge to claim transactions on the
South Internal Bus. The BWBAR defines the base address and describes the required
memory block size; see
Section 6.5.5, “Determining Block Sizes for Memory Windows”
. The selected base address needs to be naturally aligned to the granularity
of the memory block size. For instance, when a 64 Kbyte memory window size is
selected, the base address needs to be 64 Kbyte address aligned (i.e., bits 15:12 of the
base address are required to be 000b).
Table 338. Bridge Window Base Address Register — BWBAR
Bit
Default
Description
31:12
FFE0 0H
Bridge Memory Window Base Address:
These bits define the actual location the Bridge responds to
for accesses to the Bridge Memory Window on the South Internal Bus.
11:00
000H
Reserved.
PCI
IOP
Attributes
Attributes
28
24
20
16
12
8
4
0
31
rw
na
rw
na
rw
na
rw
na
rw
na
rw
na
rw
na
rw
na
rw
na
rw
na
rw
na
rw
na
rw
na
rw
na
rw
na
rw
na
rw
na
rw
na
rw
na
rw
na
rv
na
rv
na
rv
na
rv
na
rv
na
rw
na
rv
na
rv
na
rv
na
rv
na
rv
na
rv
na
Attribute Legend:
RV = Reserved
PR = Preserved
RS = Read/Set
RW = Read/Write
RC = Read Clear
RO = Read Only
NA = Not Accessible
Intel XScale
®
processor Local Bus Address
Offset
+1780H
South XBG