to add fan speed display in rpm, as of now it display only in percent

[meetshamsher]

Signed-off-by: Sardar Shamsher Singh meetshamsher@gmail.com

Description

Add get_speed_rpm() to common FanBase interface
Adds method stub with docstring and NotImplementedError in base class
Enables platform implementations to expose fan speed in RPM
Keeps backward-compatible base behavior for platforms not implementing it yet.

Motivation and Context

Why is this change required? What problem does it solve?
 If this pull request closes/resolves an open Issue, make sure you
 include the text "fixes #xxxx", "closes #xxxx" or "resolves #xxxx" here
 Currently fan speed is getting populated as percentage value but also needed values in rpm as well. 
 To update RPM values in redis DB to use it further for display.
 So this change will keep backward compatible for platform which has not yet implemented.

How Has This Been Tested?

Loaded image in local target and checked for rdis-db data population as show below:
Note: the setup contains two PSU and 4 Fan tray with each two fans.
root@sonic:/home/admin# sonic-db-cli STATE_DB KEYS 'FAN_INFO|' | sort | while read -r k; do printf '%-28s %s\n' "$k" "$(sonic-db-cli STATE_DB HGET "$k" speed_rpm)"; done
FAN_INFO|fantray1.fan1 12134
FAN_INFO|fantray1.fan2 10325
FAN_INFO|fantray2.fan1 12026
FAN_INFO|fantray2.fan2 10305
FAN_INFO|fantray3.fan1 12162
FAN_INFO|fantray3.fan2 10285
FAN_INFO|fantray4.fan1 12053
FAN_INFO|fantray4.fan2 10246
FAN_INFO|PSU1.fan1 10080
FAN_INFO|PSU2.fan1 9952
root@sonic:/home/admin#
root@sonic:/home/admin# for k in $(sonic-db-cli STATE_DB KEYS "FAN_INFO|"); do echo "=== $k ==="; sonic-db-cli STATE_DB HGETALL "$k"; echo; done
=== FAN_INFO|PSU1.fan1 ===
{'presence': 'True', 'status': 'True', 'direction': 'N/A', 'speed': '50', 'speed_rpm': '10080', 'timestamp': '20260602 11:06:27', 'led_status': 'N/A', 'drawer_name': 'N/A', 'model': 'NXA-PAC-500W-PE', 'serial': 'LIT2709A9HY', 'speed_target': '50', 'is_under_speed': 'False', 'is_over_speed': 'False', 'is_replaceable': 'False'}

=== FAN_INFO|fantray1.fan1 ===
{'presence': 'True', 'drawer_name': 'fantray1', 'model': 'NXA-SFAN-35CFM-PE', 'serial': 'DCH2936TJEW25372537A0', 'status': 'True', 'direction': 'exhaust', 'speed': '49', 'speed_rpm': '12134', 'speed_target': '53', 'is_under_speed': 'False', 'is_over_speed': 'False', 'is_replaceable': 'False', 'timestamp': '20260602 11:06:27', 'led_status': 'green'}

=== FAN_INFO|fantray2.fan2 ===
{'presence': 'True', 'drawer_name': 'fantray2', 'model': 'NXA-SFAN-35CFM-PE', 'serial': 'DCH2936TJ9625372537A0', 'status': 'True', 'direction': 'exhaust', 'speed': '49', 'speed_rpm': '10305', 'speed_target': '53', 'is_under_speed': 'False', 'is_over_speed': 'False', 'is_replaceable': 'False', 'timestamp': '20260602 11:06:27', 'led_status': 'green'}

=== FAN_INFO|PSU2.fan1 ===
{'presence': 'True', 'status': 'True', 'direction': 'N/A', 'speed': '50', 'speed_rpm': '9952', 'timestamp': '20260602 11:06:27', 'led_status': 'N/A', 'drawer_name': 'N/A', 'model': 'NXA-PAC-500W-PE', 'serial': 'LIT2709A9DV', 'speed_target': '50', 'is_under_speed': 'False', 'is_over_speed': 'False', 'is_replaceable': 'False'}

=== FAN_INFO|fantray2.fan1 ===
{'presence': 'True', 'drawer_name': 'fantray2', 'model': 'NXA-SFAN-35CFM-PE', 'serial': 'DCH2936TJ9625372537A0', 'status': 'True', 'direction': 'exhaust', 'speed': '49', 'speed_rpm': '12026', 'speed_target': '53', 'is_under_speed': 'False', 'is_over_speed': 'False', 'is_replaceable': 'False', 'timestamp': '20260602 11:06:27', 'led_status': 'green'}

=== FAN_INFO|fantray3.fan1 ===
{'presence': 'True', 'drawer_name': 'fantray3', 'model': 'NXA-SFAN-35CFM-PE', 'serial': 'DCH2936TJZK25372537A0', 'status': 'True', 'direction': 'exhaust', 'speed': '49', 'speed_rpm': '12162', 'speed_target': '53', 'is_under_speed': 'False', 'is_over_speed': 'False', 'is_replaceable': 'False', 'timestamp': '20260602 11:06:27', 'led_status': 'green'}

=== FAN_INFO|fantray4.fan2 ===
{'presence': 'True', 'drawer_name': 'fantray4', 'model': 'NXA-SFAN-35CFM-PE', 'serial': 'DCH2936TJZT25372537A0', 'status': 'True', 'direction': 'exhaust', 'speed': '48', 'speed_rpm': '10246', 'speed_target': '53', 'is_under_speed': 'False', 'is_over_speed': 'False', 'is_replaceable': 'False', 'timestamp': '20260602 11:06:27', 'led_status': 'green'}

=== FAN_INFO|fantray4.fan1 ===
{'presence': 'True', 'drawer_name': 'fantray4', 'model': 'NXA-SFAN-35CFM-PE', 'serial': 'DCH2936TJZT25372537A0', 'status': 'True', 'direction': 'exhaust', 'speed': '49', 'speed_rpm': '12053', 'speed_target': '53', 'is_under_speed': 'False', 'is_over_speed': 'False', 'is_replaceable': 'False', 'timestamp': '20260602 11:06:27', 'led_status': 'green'}

=== FAN_INFO|fantray1.fan2 ===
{'presence': 'True', 'drawer_name': 'fantray1', 'model': 'NXA-SFAN-35CFM-PE', 'serial': 'DCH2936TJEW25372537A0', 'status': 'True', 'direction': 'exhaust', 'speed': '49', 'speed_rpm': '10325', 'speed_target': '53', 'is_under_speed': 'False', 'is_over_speed': 'False', 'is_replaceable': 'False', 'timestamp': '20260602 11:06:27', 'led_status': 'green'}

=== FAN_INFO|fantray3.fan2 ===
{'presence': 'True', 'drawer_name': 'fantray3', 'model': 'NXA-SFAN-35CFM-PE', 'serial': 'DCH2936TJZK25372537A0', 'status': 'True', 'direction': 'exhaust', 'speed': '49', 'speed_rpm': '10285', 'speed_target': '53', 'is_under_speed': 'False', 'is_over_speed': 'False', 'is_replaceable': 'False', 'timestamp': '20260602 11:06:27', 'led_status': 'green'}

root@sonic:/home/admin#

Additional Information (Optional)

Related sonic-platform-daemons change PR: sonic-net/sonic-platform-daemons#888

[linux-foundation-easycla]

The committers listed above are authorized under a signed CLA.

• ✅ login: meetshamsher / name: Sardar Shamsher Singh (f1b2d77)

[azure-pipelines]

Azure Pipelines:
There may be pipelines that require an authorized user to comment /azp run to run.

[mssonicbld]

/azp run

[azure-pipelines]

Azure Pipelines:
Successfully started running 1 pipeline(s).

[mssonicbld]

/azp run

[azure-pipelines]

Azure Pipelines:
Successfully started running 1 pipeline(s).

[mssonicbld]

Hi, there are workflow run(s) waiting for approval, you may be first-time contributor. I will notify maintainers to help approve once PR is approved. Thanks!

_{---Powered by SONiC BuildBot}

[meetshamsher]

@maintainer Please add reviewer for this PR. It seems I don't have permission to add any reviewer.
Any platform side reviewer should be fine like keboliu, Junchao-Mellanox, lguohan, judyjoseph,...