Datasheet

Intel
®
Xeon
®
Processor C5500/C3500 Series
February 2010 Datasheet, Volume 1
Order Number: 323103-001 95
Interfaces
The SMBus interface uses an internal register stack that is filled by the SMBus master
before a request to the config master block is made. Table 50 provides a list of the
bytes in the stack and their descriptions.
2.3.5 Addressing
The slave address that each component claims is dependent on the DMI_PE_CFG# pin
strap (sampled on the assertion of PWRGOOD). The IIO claims SMBus accesses with
address[7:1] = 1110_1X0. The X’s represent inversion of the DMI_PE_CFG# strap pin
on the IIO. See Table 51 for the mapping of strap pins to the bit positions of the slave
address.
Note: The slave address is dependent on the DMI_PE_CFG# strap pin only and cannot be
reprogrammed.
Table 50. Internal SMBus Protocol Stack
SMBus Stack usage
for bus/dev/func
commands
(cmd[5] = 0)
SMBus Stack usage
for memory region
commands
(cmd[5] = 1)
Description
Command Command Command byte
Byte Count Byte Count
The number of bytes for this transaction when Block
command is used.
Bus Number Memory region
Bus number for bus/dev config space command
type.
Memory region for memory config space command
type.
Device/Function Address [23:16]
Device[4:0] and Function[2:0] for cmd[5] = 0 type
of config transaction.
Address[23:16] for cmd[5] = 1 type of memory
config transaction.
Register Offset Address [15:8]
The following fields are further defined for
cmd[5]=0:
Address High[7:4] = Reserved[3:0]
Address High [3:0] = Register Offset[11:8]: This is
the high order PCIe address field.
The following fields are further defined for
cmd[5]=1:
Address[15:8]
Register Offset Address [7:0]
The following fields are further defined for
cmd[5]=0:
Lower order 8-bit register offset (Address[7:0])
The following fields are further defined for
cmd[5]=1:
Address [7:0]
Data3 Data3 Data byte 3
Data2 Data2 Data byte 2
Data1 Data1 Data byte 1
Data0 Data0 Data byte 0
Table 51. SMBus Slave Address Format
Slave Address Field Bit Position Slave Address Source
[7] 1
[6] 1
[5] 1