Default implementation of under/over speed checks

[spilkey-cisco]

Description

Provide default implementation of fan under and over speed threshold checks, providing backwards compatibility for vendors that only implement get_speed_tolerance

Motivation and Context

Fan under/over speed checks should be vendor customizable, since a tolerance based off the pwm/percentage fan speed can easily give false failures, especially for low fan speeds.

How Has This Been Tested?

root@sonic:/home/cisco# echo 10000 > /opt/cisco/etc/fantray0.fan0.rpm
root@sonic:/home/cisco# grep thermalctld /var/log/syslog
<snip>
May 19 05:09:47.763970 sonic WARNING pmon#thermalctld: Fan high speed warning: fantray0.fan0 current speed=91, target speed=20
May 19 05:09:51.129298 sonic INFO pmon#supervisord 2023-05-19 05:09:51,128 INFO success: thermalctld entered RUNNING state, process has stayed up for > than 10 seconds (startsecs)
May 19 05:10:01.347935 sonic INFO pmon#supervisord: thermalctld WARNING:cisco.pacific.thermal.thermal_zone:level minor: fantray0.fan0: pwm 20; motor out of tolerance @ rpm 10000; maximum rpm 2950
root@sonic:/home/cisco# echo 2400 > /opt/cisco/etc/fantray0.fan0.rpm
root@sonic:/home/cisco# grep thermalctld /var/log/syslog
<snip>
May 19 05:09:47.763970 sonic WARNING pmon#thermalctld: Fan high speed warning: fantray0.fan0 current speed=91, target speed=20
May 19 05:09:51.129298 sonic INFO pmon#supervisord 2023-05-19 05:09:51,128 INFO success: thermalctld entered RUNNING state, process has stayed up for > than 10 seconds (startsecs)
May 19 05:10:01.347935 sonic INFO pmon#supervisord: thermalctld WARNING:cisco.pacific.thermal.thermal_zone:level minor: fantray0.fan0: pwm 20; motor out of tolerance @ rpm 10000; maximum rpm 2950
May 19 05:10:47.023156 sonic NOTICE pmon#thermalctld: Fan high speed warning cleared: fantray0.fan0 speed is back to normal

[amulyan7]

LGTM

[bmridul]

This file seems to have stub implementations. Do we need to provide a reference implementation (which may not work for some vendor..)

[spilkey-cisco]

This default implementation is provided for backwards compatibility. Any vendors who were happy with the way tolerance calculations worked do not need to change their code; they continue to just have get_speed_tolerance implemented, and these default implementations of is_under/over_speed do the previously expected tolerance calculation.

[spilkey-cisco]

Closing to open new PR to merge into sonic-net/sonic-platform-common

[spilkey-cisco]

sonic-net#382