Fix issue: watchdogutil command does not work

Conflicts:
	platform/mellanox/mlnx-platform-api/sonic_platform/watchdog.py
	platform/mellanox/mlnx-platform-api/tests/test_watchdog.py

Conflicts:
	platform/mellanox/mlnx-platform-api/sonic_platform/watchdog.py
	src/dhcpmon

platform/mellanox/mlnx-platform-api/sonic_platform/watchdog.py

@@ -27,6 +27,7 @@
 import time
 
 from sonic_platform_base.watchdog_base import WatchdogBase
+from . import utils
 
 """ ioctl constants """
 IO_WRITE = 0x40000000
@@ -80,15 +81,17 @@ def __init__(self, wd_device_path):
         super(WatchdogImplBase, self).__init__()
 
         self.watchdog_path = wd_device_path
-        self.watchdog = self.open_handle()
+        self._watchdog = None
+        self.timeout = self._gettimeout()
 
-        # Opening a watchdog descriptor starts
-        # watchdog timer;
-        # by default it should be stopped
-        self._disablecard()
-        self.armed = False
+    @property
+    def watchdog(self):
+        if self._watchdog is None:
+            self._watchdog = self.open_handle()
+        return self._watchdog
 
-        self.timeout = self._gettimeout()
+    def open_handle(self):
+        return os.open(self.watchdog_path, os.O_WRONLY)
 
     def open_handle(self):
         return os.open(self.watchdog_path, os.O_WRONLY)
@@ -134,21 +137,15 @@ def _gettimeout(self):
         @return watchdog timeout
         """
 
-        req = array.array('I', [0])
-        fcntl.ioctl(self.watchdog, WDIOC_GETTIMEOUT, req, True)
-
-        return int(req[0])
+        return utils.read_int_from_file('/run/hw-management/watchdog/main/timeout')
 
     def _gettimeleft(self):
         """
         Get time left before watchdog timer expires
         @return time left in seconds
         """
 
-        req = array.array('I', [0])
-        fcntl.ioctl(self.watchdog, WDIOC_GETTIMELEFT, req, True)
-
-        return int(req[0])
+        return utils.read_int_from_file('/run/hw-management/watchdog/main/timeleft')
 
     def arm(self, seconds):
         """
@@ -162,11 +159,10 @@ def arm(self, seconds):
         try:
             if self.timeout != seconds:
                 self.timeout = self._settimeout(seconds)
-            if self.armed:
+            if self.is_armed():
                 self._keepalive()
             else:
                 self._enablecard()
-                self.armed = True
             ret = self.timeout
         except IOError:
             pass
@@ -179,10 +175,9 @@ def disarm(self):
         """
 
         disarmed = False
-        if self.armed:
+        if self.is_armed():
             try:
                 self._disablecard()
-                self.armed = False
                 disarmed = True
             except IOError:
                 pass
@@ -194,7 +189,7 @@ def is_armed(self):
         Implements is_armed WatchdogBase API
         """
 
-        return self.armed
+        return utils.read_str_from_file('/run/hw-management/watchdog/main/state') == 'active'
 
     def get_remaining_time(self):
         """
@@ -203,7 +198,7 @@ def get_remaining_time(self):
 
         timeleft = WD_COMMON_ERROR
 
-        if self.armed:
+        if self.is_armed():
             try:
                 timeleft = self._gettimeleft()
             except IOError:
@@ -216,13 +211,15 @@ def __del__(self):
         Close watchdog
         """
 
-        os.close(self.watchdog)
+        if self._watchdog is not None:
+            os.close(self._watchdog)
 
 
 class WatchdogType1(WatchdogImplBase):
     """
     Watchdog type 1
     """
+    TIMESTAMP_FILE = '/tmp/nvidia/watchdog_timestamp'
 
     def arm(self, seconds):
         """
@@ -233,7 +230,8 @@ def arm(self, seconds):
         ret = WatchdogImplBase.arm(self, seconds)
         # Save the watchdog arm timestamp
         # requiered for get_remaining_time()
-        self.arm_timestamp = time.time()
+        os.makedirs('/tmp/nvidia', exist_ok=True)
+        utils.write_file(self.TIMESTAMP_FILE, str(time.time()))
 
         return ret
 
@@ -246,8 +244,9 @@ def get_remaining_time(self):
 
         timeleft = WD_COMMON_ERROR
 
-        if self.armed:
-            timeleft = int(self.timeout - (time.time() - self.arm_timestamp))
+        if self.is_armed():
+            arm_timestamp = utils.read_float_from_file(self.TIMESTAMP_FILE)
+            timeleft = int(self.timeout - (time.time() - arm_timestamp))
 
         return timeleft