sbtsi: Add support to reporting SBTSI maximum HBM temperature

[bges]

Add a new channel to support SBTSIx50 and SBTSIx54 for reporting maximum HBM temperature.

Test result on MI300C platform
CPU temperature:
$ cat /sys/bus/i3c/drivers/sbtsi_i3c/0-22400000001/hwmon/hwmon16/temp1_input
41750

Max HBM Temperature:
$ cat /sys/bus/i3c/drivers/sbtsi_i3c/0-22400000001/hwmon/hwmon16/temp2_input
32000

[akky16]

Thank you for raising the PR, can you please help to address few review comments?

[bges]

Add the Label, Max and Min:

# cat temp1_label 
CpuTemp
# cat temp1_input 
42750
# cat temp1_max   
98000
# cat temp1_min 
0

# cat temp2_label 
MaxMemTemp
# cat temp2_input 
33000
# cat temp2_max   
98000
# cat temp2_min 
1000

[nchatrad]

Akshay, TSI registers 0x50 and 0x54 do not report any value on EPYC processors, SB-TSI driver has no way to know the platform to conditionally support the hwmon entries.

HBM temp information is available via APML, DIMM temp info is also available for EPYC processors, as SBRMI driver is aware of the platform via CPUID or simliar. can we expose hwmon entries for HBM/DIMM temp from SBRMI instead.

[akky16]

SBRMI through mailbox provides way to get the max HBM temp (highest of all stacks) using mailbox command 0xA1,
will implement the required changes in SBRMI to support this.

[akky16]

Hi @bges

HBM is only applicable for MI and not for EPYC platforms.
As, the modules are generic for MI and EPYC, the HBM reporting will not be correct to report as its not applicable.
Currently there is no option to Identify platform in TSI.

We can approve this PR for a branch, but upstreaming is difficult.