Using the SMBus to access the BMC

[RedLion]

Hi,

What I would like to do is to read all kind of sensor data out of the
BMC (Baseboard Management Controller), lets take for example the
processor temperature.As far as I've heard and read this can be done
though the BMC?

I'm developing with C on a FreeBSD kernel. It's an Intel SE7210TP1-E
TPS motherboard. It supports IPMI 2.0. And the mBMC chip on the
motherboard is from National Semiconductor PC87431 interated
management controller.

As far as I've found in the documentation the BMC can be accessed
through two interfaces on this motherboard:
- SMBus
- LOM (Lan On Motherboard)

I would like to accomplish this using the SMBus, and can be found on
/dev/smb0. This is working, but then find the BMC. So I scan through
the addresses 0x20 till 0x4f and send the command 0x03 (Get UDID = get
Unique Device Identifier) for this I take an SMB frame as in the
machine/smb.h is defined. Looking in the documentation it explains
that the Device capabilitities field within the UDID frame which is
returned in the smb frame should have the value 38(dec). When trying
this with the folowing code I don't get an result that makes any
sense????

[CODE]
#include <unistd.h>
#include <stdio.h>
#include <string.h>
#include <fcntl.h>
#include <machine/smb.h>
#include <stdlib.h>
#include <err.h>

/* scan */
int fd;
struct smbcmd s;
int i;
short n;
char data[32];

if ((fd = open("/dev/smb0", O_RDWR)) < 0)
warn("unable to open smb");

for (n = 0x20; n < 0x4f; n++) {
s.slave = n;
s.cmd = 3;
s.count = 17;
s.data.byte_ptr = data;
memset(s.data.byte_ptr, 0, s.count);
if (ioctl(fd, SMB_BREAD, &s) < 0)
continue;

printf("slave = 0x%02X data = ", n);
for (i = 0; i < s.count; i++) {
printf("%02X ",
((unsigned int)s.data.byte_ptr[i] & 0x00ff));
}
putchar('\n');
}
close(fd);
[/CODE]

I just got 4 responses from devices, and from the data returned I
can't make up what devices they are?
It looks more if the data returned is incorrect, and have nothing to
do with the request.

Am I following the right way to achieve this?

Has anyone done this before? Is there any example code around to find?

I have already posted to some other groups, but never had any
responses, or a response telling me to post in an other group...

And now I got really stuck, any help or ideas even responses will be
appreciated!!!

Thanks,

Charl