[Mellanox] add PSU input voltage and current (#11510)

- Why I did it
Add PSU input voltage and input current to mlnx platform api.

- How I did it
Implement 2 function of getting the psu voltage and psu current input:
Get the values from "power/psu{}_curr_in" , "power/psu{}_volt_in"

- How to verify it
Manual test.
Run sonic-mgmt regression

Signed-off-by: orfar1994 <orfar1994@gmail.com>

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

@@ -190,12 +190,32 @@ class FixedPsu(PsuBase):
         """
         return None
 
+    def get_input_voltage(self):
+        """
+        Retrieves current PSU voltage input
+
+        Returns:
+            A float number, the input voltage in volts, 
+            e.g. 12.1 
+        """
+        return None
+
+    def get_input_current(self):
+        """
+        Retrieves the input current draw of the power supply
+
+        Returns:
+            A float number, the electric current in amperes, e.g 15.4
+        """
+        return None
 
 class Psu(FixedPsu):
     """Platform-specific Psu class"""
     PSU_CURRENT = "power/psu{}_curr"
     PSU_POWER = "power/psu{}_power"
     PSU_VPD = "eeprom/psu{}_vpd"
+    PSU_CURRENT_IN = "power/psu{}_curr_in"
+    PSU_VOLT_IN = "power/psu{}_volt_in"
 
     shared_led = None
 
@@ -207,7 +227,10 @@ class Psu(FixedPsu):
         self._psu_voltage_max = None
         self._psu_voltage_capability = None
 
+        self.psu_voltage_in = os.path.join(PSU_PATH, self.PSU_VOLT_IN.format(self.index))
+
         self.psu_current = os.path.join(PSU_PATH, self.PSU_CURRENT.format(self.index))
+        self.psu_current_in = os.path.join(PSU_PATH, self.PSU_CURRENT_IN.format(self.index))
         self.psu_power = os.path.join(PSU_PATH, self.PSU_POWER.format(self.index))
         self.psu_power_max = self.psu_power + "_max"
         self.psu_presence = os.path.join(PSU_PATH, "thermal/psu{}_status".format(self.index))
@@ -457,6 +480,30 @@ class Psu(FixedPsu):
         else:
             return None
 
+    def get_input_voltage(self):
+        """
+        Retrieves current PSU voltage input
+
+        Returns:
+            A float number, the input voltage in volts, 
+            e.g. 12.1 
+        """
+        if self.get_powergood_status():
+            voltage = utils.read_int_from_file(self.psu_voltage_in, log_func=logger.log_info)
+            return float(voltage) / 1000
+        return None
+
+    def get_input_current(self):
+        """
+        Retrieves the input current draw of the power supply
+
+        Returns:
+            A float number, the electric current in amperes, e.g 15.4
+        """
+        if self.get_powergood_status():
+            amperes = utils.read_int_from_file(self.psu_current_in, log_func=logger.log_info)
+            return float(amperes) / 1000
+        return None
 
 class InvalidPsuVolWA:
     """This class is created as a workaround for a known hardware issue that the PSU voltage threshold could be a 

platform/mellanox/mlnx-platform-api/tests/test_psu.py

@@ -49,6 +49,8 @@ class TestPsu:
         assert psu.is_replaceable() is False
         assert psu.get_temperature() is None
         assert psu.get_temperature_high_threshold() is None
+        assert psu.get_input_voltage() is None
+        assert psu.get_input_current() is None
 
     @mock.patch('os.path.exists', mock.MagicMock(return_value=True))
     def test_psu(self):
@@ -64,7 +66,9 @@ class TestPsu:
             psu.psu_current: 20345,
             psu.psu_power: 30456,
             psu.psu_temp: 40567,
-            psu.psu_temp_threshold: 50678
+            psu.psu_temp_threshold: 50678,
+            psu.psu_voltage_in: 102345,
+            psu.psu_current_in: 676,
         }
 
         def mock_read_int_from_file(file_path, **kwargs):
@@ -85,6 +89,8 @@ class TestPsu:
         assert psu.get_power() is None
         assert psu.get_temperature() is None
         assert psu.get_temperature_high_threshold() is None
+        assert psu.get_input_voltage() is None
+        assert psu.get_input_current() is None
 
         mock_sysfs_content[psu.psu_oper_status] = 1
         assert psu.get_voltage() == 10.234
@@ -94,6 +100,8 @@ class TestPsu:
         assert psu.get_power() == 0.030456
         assert psu.get_temperature() == 40.567
         assert psu.get_temperature_high_threshold() == 50.678
+        assert psu.get_input_voltage() == 102.345
+        assert psu.get_input_current() == 0.676
 
         assert psu.get_position_in_parent() == 1
         assert psu.is_replaceable() is True