[Mellanox] Adopt single way to get fan direction for all ASIC types (#…

…7386)

#### Why I did it
Adopt a single way to get fan direction for all ASIC types.
It depends on hw-mgmt V.7.0010.2000.2303. Depends on #7419

#### How I did it
Originally, the get_direction was implemented by fetching and parsing `/var/run/hw-management/system/fan_dir` on the Spectrum-2 and the Spectrum-3 systems. It isn't supported on the Spectrum system.
Now, it is implemented by fetching `/var/run/hw-management/thermal/fanX_dir` for all the platforms.

Signed-off-by: Stephen Sun <stephens@nvidia.com>

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

@@ -10,7 +10,7 @@
             'drawer_num': 4,
             'drawer_type': 'real',
             'fan_num_per_drawer': 2,
-            'support_fan_direction': False,
+            'support_fan_direction': True,
             'hot_swappable': True
         },
         'psus': {
@@ -31,7 +31,7 @@
             'drawer_num': 4,
             'drawer_type': 'real',
             'fan_num_per_drawer': 1,
-            'support_fan_direction': False,
+            'support_fan_direction': True,
             'hot_swappable': True
         },
         'psus': {
@@ -52,7 +52,7 @@
             'drawer_num': 1,
             'drawer_type': 'virtual',
             'fan_num_per_drawer': 4,
-            'support_fan_direction': False,
+            'support_fan_direction': True,
             'hot_swappable': False
         },
         'psus': {
@@ -73,7 +73,7 @@
             'drawer_num': 4,
             'drawer_type': 'real',
             'fan_num_per_drawer': 2,
-            'support_fan_direction': False,
+            'support_fan_direction': True,
             'hot_swappable': True
         },
         'psus': {
@@ -94,7 +94,7 @@
             'drawer_num': 1,
             'drawer_type': 'virtual',
             'fan_num_per_drawer': 4,
-            'support_fan_direction': False,
+            'support_fan_direction': True,
             'hot_swappable': False
         },
         'psus': {

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

@@ -22,8 +22,10 @@
 
 FAN_PATH = "/var/run/hw-management/thermal/"
 CONFIG_PATH = "/var/run/hw-management/config"
-# fan_dir isn't supported on Spectrum 1. It is supported on Spectrum 2 and later switches
-FAN_DIR = "/var/run/hw-management/system/fan_dir"
+
+FAN_DIR = "/var/run/hw-management/thermal/fan{}_dir"
+FAN_DIR_VALUE_EXHAUST = 0
+FAN_DIR_VALUE_INTAKE = 1
 COOLING_STATE_PATH = "/var/run/hw-management/thermal/cooling_cur_state"
 
 class Fan(FanBase):

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

@@ -14,6 +14,7 @@
     from sonic_platform_base.fan_drawer_base import FanDrawerBase
     from sonic_platform_base.fan_base import FanBase
     from .led import FanLed, SharedLed
+    from .utils import read_int_from_file
 except ImportError as e:
     raise ImportError (str(e) + "- required module not found")
 
@@ -51,14 +52,14 @@ def get_direction(self):
             return FanBase.FAN_DIRECTION_NOT_APPLICABLE
 
         try:
-            from .fan import FAN_DIR
-            with open(FAN_DIR, 'r') as fan_dir:
-                fan_dir_bits = int(fan_dir.read())
-                fan_mask = 1 << self._index - 1
-                if fan_dir_bits & fan_mask:
-                    return FanBase.FAN_DIRECTION_INTAKE
-                else:
-                    return FanBase.FAN_DIRECTION_EXHAUST
+            from .fan import FAN_DIR, FAN_DIR_VALUE_INTAKE, FAN_DIR_VALUE_EXHAUST
+            fan_dir = read_int_from_file(FAN_DIR.format(self._index), raise_exception=True)
+            if fan_dir == FAN_DIR_VALUE_INTAKE:
+                return FanBase.FAN_DIRECTION_INTAKE
+            elif fan_dir == FAN_DIR_VALUE_EXHAUST:
+                return FanBase.FAN_DIRECTION_EXHAUST
+            else:
+                raise RuntimeError("Got wrong value {} for fan direction {}".format(fan_dir, self._index))
         except (ValueError, IOError) as e:
             raise RuntimeError("Failed to read fan direction status to {}".format(repr(e)))