SDM Mailbox access in intel agilex 5

Yes, that is correct. ATF is the middleman for all the mailbox communication to SDM.

The HPS HWMON software driver sends the SMC Call to ATF when then sends the HWMON READVOLT to SDM.

Make sure your Linux OS build has CONFIG_SENSORS_SOC64=y.

On Linux check if the HWMON driver is probed successful

root@agilex:/# dmesg | grep "soc64"

[ 1.268886] soc64_hwmon_probe

[ 1.271949] soc64_hwmon_probe Initialized 1 temperature and 6 voltage channels

[ 1.271957] soc64-hwmon soc:firmware:hwmon: Initialized 1 temperature and 6 voltage channels

Read the temperature or voltages like this

~# cat /sys/devices/platform/soc:firmware:svc/soc:firmware:svc:hwmon/hwmon/hwmon1/temp1_input

78125

~# cat /sys/devices/platform/soc:firmware:svc/soc:firmware:svc:hwmon/hwmon/hwmon1/temp2_input

82125

~# cat /sys/devices/platform/soc:firmware:svc/soc:firmware:svc:hwmon/hwmon/hwmon1/temp3_input

80875

:~# cat /sys/devices/platform/soc:firmware:svc/soc:firmware:svc:hwmon/hwmon/hwmon1/temp4_input

76375