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IPMI Controller: IPMI Message Protocol
Katana
®
752i User’s Manual 10006024-04
11-14
Master Write-Read I
2
C (Application)
The Master Write-Read I
2
C command allows for direct accesses to I
2
C devices. This com-
mand can read from or write to any of the Zircon PM’s private I
2
C devices, such as SROMs or
temperature sensors. Typically, you would use it to update the Zircon PM’s firmware from
the management controller.
Table 11-10 shows the request/response data parameters for
this command.
Table 11-10: Master Write-Read I
2
C Parameters
Type: Byte: Data Field:
Request
Data
1Bus ID
Bits[7:4], Channel Number. Write as 0000 (binary).
Bits[3:1], Bus ID, zero-based
000=Public IPMB
001=Private IIC Bus #1, Private IPMB
111=Private IIC Bus #2
Bit[0], Bus Type
0=Public (IPMB)
1=Private Bus
2 Bits[7:1], Slave Address of Recipient
Bit[0], Reserved. Write as zero.
3 Read Count. Number of bytes to read, one-based.
0=No bytes to read.
4:M Data to Write
Response
Data
1Completion Code
A management controller shall return an error Completion Code
if an attempt is made to access an unsupported bus.
Generic, plus following command-specific codes (hex):
81=Lost Arbitration
82=Bus Error
83=NAK on Write
84=Truncated Read
2:N Bytes read from specified slave address. This field will be absent if
the read count is 0. The controller terminates the I
2
C transaction
with a STOP condition after reading the requested number of
bytes.