[AS4625-54P/T] sync log to SSD before OTP shutdown

[roger530-ho]

Why I did it

The shutdown message will be lost during OTP shutdown.

How I did it

sync log to SSD before OTP shutdown

How to verify it

Setup Test Environment

1. Modify /usr/local/lib/python3.9/dist-packages/sonic_platform/thermal.py:{}init{}(...)
   self.hwmon_path = "/home/admin/"
2. Add following to /etc/rc.local

   echo 31000 > /home/admin/temp1_input
   exit 0 
   

3. Reboot

Before Modification

1. Produce fake temperature data

   admin@as4625-54t-1:~$ sudo su
   root@as4625-54t-1:/home/admin# cat /dev/null > /var/log/syslog
   root@as4625-54t-1:/home/admin#
   root@as4625-54t-1:/home/admin# echo 85000 > temp1_input
   root@as4625-54t-1:/home/admin#
   

2. Power Cycling
   Log :
   AS4625-54T_Before_Modification.log
   AS4625-54P_Before_Modification.log

After Modification

1. Add the following code to /usr/local/bin/accton_as4625_54t_monitor.py:manage_fans()

......
    import subprocess
    import sonic_platform.platform
            ......
        if self.shutdown is True:
            # critical case*/
            logging.critical(
                'Alarm-Critical for temperature critical is detected, trigger thermal shutdown')
            ## Sync log buffer to disk
            cmd_str="sync"
            status, output = subprocess.getstatusoutput(cmd_str)
            cmd_str="/sbin/fstrim -av"
            status, output = subprocess.getstatusoutput(cmd_str)
            time.sleep(3)
 
            path = I2C_PATH.format('0', '64') + 'thermal_shutdown'
            time.sleep(2)
            self._api_helper.write_txt_file(path, 1)
 
            logging.critical(
                'Alarm-Critical for temperature critical is detected, shutdown DUT')
            ## Sync log buffer to disk
            cmd_str="sync"
            status, output = subprocess.getstatusoutput(cmd_str)
            cmd_str="/sbin/fstrim -av"
            status, output = subprocess.getstatusoutput(cmd_str)
            time.sleep(3)
 
            path = I2C_PATH.format('0', '64') + 'pwr_enable_mb'
            time.sleep(2)
            self._api_helper.write_txt_file(path, 0)

2. Produce fake temperature data

   root@as4625-54t-1:/home/admin# systemctl restart as4625-54t-platform-monitor.service
   root@as4625-54t-1:/home/admin# cat /dev/null > /var/log/syslog
   root@as4625-54t-1:/home/admin# echo 85000 > temp1_input
   root@as4625-54t-1:/home/admin# 
   root@as4625-54t-1:/home/admin# 
   

3. Power Cycling
   Log :
   AS4625-54T_After_Modification.log
   AS4625-54P_After_Modification.log

Which release branch to backport (provide reason below if selected)

Description for the changelog

Ensure to add label/tag for the feature raised. example - PR#2174 under sonic-utilities repo. where, Generic Config and Update feature has been labelled as GCU.

Link to config_db schema for YANG module changes

A picture of a cute animal (not mandatory but encouraged)