From b2286a24dc969e031f3226d57b95ec809d35c99e Mon Sep 17 00:00:00 2001
From: Stephen Sun <5379172+stephenxs@users.noreply.github.com>
Date: Tue, 4 May 2021 08:10:18 +0800
Subject: [PATCH] [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 https://github.com/Azure/sonic-buildimage/pull/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>
---
 .../sonic_platform/device_data.py               | 10 +++++-----
 .../mlnx-platform-api/sonic_platform/fan.py     |  6 ++++--
 .../sonic_platform/fan_drawer.py                | 17 +++++++++--------
 3 files changed, 18 insertions(+), 15 deletions(-)

diff --git a/platform/mellanox/mlnx-platform-api/sonic_platform/device_data.py b/platform/mellanox/mlnx-platform-api/sonic_platform/device_data.py
index a52886a9de..e1124d0d55 100644
--- a/platform/mellanox/mlnx-platform-api/sonic_platform/device_data.py
+++ b/platform/mellanox/mlnx-platform-api/sonic_platform/device_data.py
@@ -10,7 +10,7 @@ DEVICE_DATA = {
             '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 @@ DEVICE_DATA = {
             '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 @@ DEVICE_DATA = {
             '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 @@ DEVICE_DATA = {
             '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 @@ DEVICE_DATA = {
             'drawer_num': 1,
             'drawer_type': 'virtual',
             'fan_num_per_drawer': 4,
-            'support_fan_direction': False,
+            'support_fan_direction': True,
             'hot_swappable': False
         },
         'psus': {
diff --git a/platform/mellanox/mlnx-platform-api/sonic_platform/fan.py b/platform/mellanox/mlnx-platform-api/sonic_platform/fan.py
index 98e5c40fc3..3ae5c4847c 100644
--- a/platform/mellanox/mlnx-platform-api/sonic_platform/fan.py
+++ b/platform/mellanox/mlnx-platform-api/sonic_platform/fan.py
@@ -22,8 +22,10 @@ PWM_MAX = 255
 
 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):
diff --git a/platform/mellanox/mlnx-platform-api/sonic_platform/fan_drawer.py b/platform/mellanox/mlnx-platform-api/sonic_platform/fan_drawer.py
index 66ee394917..fcf9b80263 100644
--- a/platform/mellanox/mlnx-platform-api/sonic_platform/fan_drawer.py
+++ b/platform/mellanox/mlnx-platform-api/sonic_platform/fan_drawer.py
@@ -14,6 +14,7 @@ try:
     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 @@ class MellanoxFanDrawer(FanDrawerBase):
             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)))