BCM1250/BCM1125/BCM1125H
User Manual
10/21/02
B r o a d c o m C o r p o r a t i o n
Page
236
Section 8: PCI Bus and HyperTransport Fabric
Document
1250_1125-UM100CB-R
HyperTransport Target Done Counter
Since the MIPS architecture does not support non-posted writes it is hard for software to tell when
HyperTransport configuration writes have completed. To help with this a counter has been implemented in the
HyperTransport Additional Status Register. This counter can be cleared by software writing a zero and will
increment every time a TgtDone message is returned from the fabric. Thus software can clear the counter, do
all the writes to configure a HyperTransport device and then poll the counter until it reaches the number of
writes performed. This will ensure the final write has been acknowledged by the device.
S
YSTEMS
T
HAT
D
O
N
OT
U
SE
H
YPER
T
RANSPORT
If a BCM1250 or BCM1125H system does not use the HyperTransport interface the mem_base, mem_limit,
io_base and io_limit registers of the HT bridge must still be programmed. This configures a shadow copy of
these registers that is by default UNPREDICTABLE. The mem_limit should be set to be lower in address than
the mem_base. The io_base upper 16 bits (bits [15:0] of offset h30 in the HyperTransport configuration header)
should be set above the 24 bit range used by the I/O space, for example the register can be written with
32’h0000F200 (note that subsequent reads will show bits [15:12] as zero). For configuration accesses to buses
other than bus 0 to work the HyperTransport secondary and subordinate bus numbers should be written with
zero. Until these registers are programmed accesses to the PCI memory or I/O space will have UNDEFINED
results.
C
ONFIGURATION
H
EADER
D
ESCRIPTIONS
The following sections describe the configuration headers used by the PCI and HyperTransport interfaces. The
PCI interface is bus=0, device=0, function=0 so the header can be accessed from within the part starting at the
base address is
00_FE00_0000
(match bits) or
00_DE00_0000
(match bytes). The HyperTransport interface
is bus=0, device=1, function=0, with base address
00_FE00_0800
(match bits) or
00_DE00_0800
(match
bytes).
The following terms are used in the register descriptions:
•
R/O. Read Only. The field contains a static value and should not be written.
•
R/W. Read/Write. The field can be modified by software.
•
R/C. Read/Clear. The field can be read to give status information. Bits may be cleared by writing a 1 to
them, writes of 0 are ignored.
PCI C
ONFIGURATION
H
EADER
The PCI configuration header is a standard Type 0 header with extensions to support the address map table.
The following table shows the fields of the header, along with the values they contain after a system reset.
Table 127: PCI Interface Configuration Header (Type 0)
Offset
Register Bits
Description
31
24
23
16
15
8
7
0
00
Device Id R/O 0001
Vendor Id R/O 166D
Identifies the device as a Broadcom SiByte
family PCI interface.
04
Status (see
R/W 02A0
Command (See
) R/W 0002
As defined by PCI standard.
Содержание BCM1125
Страница 18: ...BCM1250 BCM1125 BCM1125H User Manual 10 21 02 Broadcom Corporation Page xviii Document 1250_1125 UM100CB R ...
Страница 28: ...BCM1250 BCM1125 BCM1125H User Manual 10 21 02 Broadcom Corporation Page xxviii Document 1250_1125 UM100CB R ...
Страница 515: ...BCM1250 BCM1125 BCM1125H User Manual 10 21 02 Broadcom Corporation Page vii Index Document 1250_1125 UM100CB R ...