support to retrieve HW watchdog in 12.8T falcon

Signed-off-by: lkunjumon <lkunjumon@marvell.com>

platform/marvell-arm64/sonic-platform-db98cx8580-32cd/db98cx8580/sonic_platform/chassis.py

@@ -305,6 +305,24 @@ def get_reboot_cause(self):
         #
         return (ChassisBase.REBOOT_CAUSE_NON_HARDWARE, None)
 
+    def get_watchdog(self):
+        """
+        Retrieves hardware watchdog device on this chassis
+
+        Returns:
+            An object derived from WatchdogBase representing the hardware
+            watchdog device
+        """
+        try:
+            if self._watchdog is None:
+                from sonic_platform.watchdog import WatchdogImplBase
+                watchdog_device_path = "/dev/watchdog0"
+                self._watchdog = WatchdogImplBase(watchdog_device_path)
+        except Exception as e:
+            sonic_logger.log_warning(" Fail to load watchdog {}".format(repr(e)))
+
+        return self._watchdog
+
     def get_change_event(self, timeout=0):
         """
         Returns a nested dictionary containing all devices which have

platform/marvell-arm64/sonic-platform-db98cx8580-32cd/db98cx8580/sonic_platform/watchdog.py

@@ -0,0 +1,133 @@
+"""
+Module contains an implementation of SONiC Platform Base API and
+provides access to hardware watchdog
+"""
+
+import os
+import fcntl
+import array
+
+from sonic_platform_base.watchdog_base import WatchdogBase
+from sonic_py_common import logger
+
+""" ioctl constants """
+IO_READ = 0x80000000
+IO_SIZE_INT = 0x00040000
+IO_TYPE_WATCHDOG = ord('W') << 8
+
+WDR_INT = IO_READ | IO_SIZE_INT | IO_TYPE_WATCHDOG
+
+""" Watchdog ioctl commands """
+WDIOC_SETOPTIONS = 4 | WDR_INT
+WDIOC_KEEPALIVE = 5 | WDR_INT
+WDIOC_GETTIMEOUT = 7 | WDR_INT
+
+""" Watchdog status constants """
+WDIOS_DISABLECARD = 0x0001
+WDIOS_ENABLECARD = 0x0002
+
+""" watchdog sysfs """
+WD_SYSFS_PATH = "/sys/class/watchdog/"
+
+WD_COMMON_ERROR = -1
+
+sonic_logger = logger.Logger()
+
+
+class WatchdogImplBase(WatchdogBase):
+    """
+    Base class that implements common logic for interacting
+    with watchdog using ioctl commands
+    """
+
+    def __init__(self, wd_device_path):
+        """
+        Open a watchdog handle
+        @param wd_device_path Path to watchdog device
+        """
+
+        self.watchdog_path = wd_device_path
+        self.watchdog = os.open(self.watchdog_path, os.O_WRONLY)
+
+        # Opening a watchdog descriptor starts
+        # watchdog timer; by default it should be stopped
+        self._disablewatchdog()
+        self.armed = False
+        self.timeout = self._gettimeout()
+
+    def disarm(self):
+        """
+        Disarm the hardware watchdog
+
+        Returns:
+            A boolean, True if watchdog is disarmed successfully, False
+            if not
+        """
+        sonic_logger.log_info(" Debug disarm watchdog ")
+
+        try:
+            self._disablewatchdog()
+            self.armed = False
+            self.timeout = 0
+        except IOError:
+            return False
+
+        return True
+
+    def _disablewatchdog(self):
+        """
+        Turn off the watchdog timer
+        """
+
+        req = array.array('h', [WDIOS_DISABLECARD])
+        fcntl.ioctl(self.watchdog, WDIOC_SETOPTIONS, req, False)
+
+    def _gettimeout(self):
+        """
+        Get watchdog timeout
+        @return watchdog timeout
+        """
+
+        req = array.array('I', [0])
+        fcntl.ioctl(self.watchdog, WDIOC_GETTIMEOUT, req, True)
+
+        return int(req[0])
+
+    def arm(self, seconds):
+        """
+        Implements arm WatchdogBase API
+        """
+        sonic_logger.log_info(" Debug arm watchdog4 ")
+        ret = WD_COMMON_ERROR
+        if seconds < 0:
+            return ret
+
+        try:
+            if self.timeout != seconds:
+                self.timeout = self._settimeout(seconds)
+            if self.armed:
+                self._keepalive()
+            else:
+                sonic_logger.log_info(" Debug arm watchdog5 ")
+                self._enablewatchdog()
+                self.armed = True
+            ret = self.timeout
+        except IOError:
+            pass
+
+        return ret
+
+    def _enablewatchdog(self):
+        """
+        Turn on the watchdog timer
+        """
+
+        req = array.array('h', [WDIOS_ENABLECARD])
+        fcntl.ioctl(self.watchdog, WDIOC_SETOPTIONS, req, False)
+
+    def _keepalive(self):
+        """
+        Keep alive watchdog timer
+        """
+
+        fcntl.ioctl(self.watchdog, WDIOC_KEEPALIVE)