Specifications

BMC Messaging Interfaces QSSC-S4R Technical Product Specification
290
x An even t is in t he even t message bu ff er
x
Wa t chdog pre- t imeou t in t errup t f lag has been se t
All condi t ions mus t be cleared and all BMC t o SMS messages mus t be f lushed f or t he SMS_ATN bi t t o be cleared .
The hos t I/ O address o f t he SMS in t er f ace is 0CA2h – 0CA3h .
The opera t ion o f t he SMS in t er f ace is described in t he I n t elligen t Pla tf orm Managemen t I n t er f ace Speci f ica t ion . See
t he chap t er t i t led , “ Keyboard Con t roller S t yle (KCS) I n t er f ace . ”
25.6.4.1 Canceling In-progress Commands
So ft ware can cancel an in-progress t ransac t ion by issuing a new WR I TE_START command t o t he in t er f ace .
However , t here are cases where t he BMC has accep t ed t he command and queued i t f or execu t ion . I n t hese cases ,
t he commands are execu t ed even i f t he t ransac t ion has been canceled .
Since t he SMS in t er f ace is single- t hreaded , t he BMC does no t accep t a new command un t il t he curren t, canceled-in-
progress
command has comple t ed execu t ion . Un t il t hen , any new command sen t via t he SMS in t er f ace is responded
t o wi t h a NODE_BUSY comple t ion code . When t he curren t, canceled-in-progress command is comple t e , t he BMC
discards t he response and t he SMS in t er f ace accep t s commands f or execu t ion .
25.6.5 SMM Interface
The SMM in t er f ace is a KCS in t er f ace t ha t is used by t he B I OS when in t er f ace response t ime is a concern , f or
example wi t h t he B I OS SM I handler . The BMC gives t his in t er f ace priori t y over o t her communica t ion in t er f aces . The
BMC has limi t s on how many back- t o-back t ransac t ions i t can handle wi t hou t loss in responsiveness . It mus t be able
t o handle up t o 30 back- t o-back commands f rom t he B I OS .
The BMC implemen t s t he op t ional Ge t S t a t us / Abor t t ransac t ion on t his in t er f ace . Only LUN 1 is suppor t ed on t his
in t er f ace .
The even t message bu ff er is shared across SMS and SMM in t er f aces . The hos t I/ O address o f t he SMM in t er f ace is
0CA4h – 0CA5h .
25.7 IPMB Communication Interface
The I PMB communica t ion in t er f ace uses t he 100 KB / s version o f an I
2
C bus as i t s physical medium . For more
in f orma t ion on I
2
C speci f ica t ions , see The I
2
C
Bus and How t o Use It. The I PMB implemen t a t ion in t he BMC is
complian t wi t h t he I PMB v1 . 0 , revision 1 . 0 .
The BMC I PMB slave address is 20h .
The BMC bo t h sends and receives I PMB messages over t he I PMB in t er f ace . Non- I PMB messages received via t he
I PMB in t er f ace are discarded .
Messages sen t by t he BMC can ei t her be origina t ed by t he BMC , such as ini t ializa t ion agen t opera t ion , or by ano t her
source . One example is KCS- I PMB bridging .
For I PMB reques t messages origina t ed by t he BMC , t he BMC implemen t s a response t imeou t in t erval o f 60 ms and a
re t ry coun t o f 3 .
25.7.1 BMC as I
2
C Master Controller on IPMB
The BMC allows access t o devices on t he I PMB as an I
2
C mas t er . The f ollowing commands are suppor t ed :
x
Send Message : This command wri t es da t a t o an I
2
C device as mas t er .
x
Mas t er Wri t e-Read : This command allows t he f ollowing ac t ions :
x
Wri t ing da t a t o an I
2
C device as a mas t er .
x
Reading da t a f rom an I
2
C device as a mas t er .
x Writing data to I
2
C device as a master, issue an I
2
C Repeated Start, and reading a specified number of bytes
from I
2
C device as a master. Errors in I
2
C transmission or reception are communicated via completion codes in
the command response.
These f unc t ions suppor t t he mos t common opera t ions f or an I
2
C mas t er con t roller . This includes access t o common
non-in t elligen t I
2
C devices like SEEPROMs . The Send Message command is used t o send I PMB messages t o
in t elligen t devices t ha t use t he I PMB pro t ocol .