[BFN]: Implement getting psu related sensors in sonic_platform directly from BMC (#12786)

Why I did it
Platform interface doesn't provide all sensors and using it isn't effective

How I did it
Request sensors via http from BMC server and parse the result

How to verify it
Related daemon in pmon populates redis db, run this command to view the contents

dockers/docker-platform-monitor/Dockerfile.j2

@@ -39,8 +39,8 @@ RUN apt-get update &&   \
 RUN pip3 install grpcio==1.39.0 \
         grpcio-tools==1.39.0
 
-# Barefoot platform vendors' sonic_platform packages import the Python 'thrift' library
-RUN pip3 install thrift==0.13.0
+# Barefoot platform vendors' sonic_platform packages import these Python libraries
+RUN pip3 install thrift==0.13.0 netifaces
 
 # We install the libpci module in order to be able to do PCI transactions
 RUN pip3 install libpci

platform/barefoot/sonic-platform-modules-bfn-montara/sonic_platform/bfn_extensions/psu_sensors.py

@@ -0,0 +1,127 @@
+from netifaces import ifaddresses, AF_INET6
+from subprocess import Popen, PIPE, DEVNULL
+import json
+import os
+
+class Metric(object):
+
+    def __init__(self, sensor_id, sensor_key, value, label):
+        self._value = self.parse_value(value)
+        self._sensor_id = sensor_id
+        self._sensor_key = sensor_key
+        self._label = label
+
+    @classmethod
+    def parse_value(cls, value):
+        parse = getattr(cls, "parse")
+        return parse(value)
+
+    # For debug purposes
+    def __repr__(self):
+        return "%s, %s: %s %s [%s]" % (
+            self._sensor_id,
+            self._sensor_key,
+            self._value,
+            getattr(self, "unit", "?"),
+            self._label)
+
+class Temperature(Metric):
+    parse = float
+    unit = "°C"
+
+class FanRpm(Metric):
+    parse = float
+    unit = "RPM"
+
+class FanFault(Metric):
+    parse = float
+
+class Voltage(Metric):
+    parse = float
+    unit = "V"
+
+class Power(Metric):
+    parse = float
+    unit = "W"
+
+class Current(Metric):
+    parse = float
+    unit = "A"
+
+def get_metric_value(metrics, name):
+    label, sensor_id, sensor_key = name.split("_")
+    for metric in metrics:
+        if metric._label == label and metric._sensor_id == sensor_id and metric._sensor_key == sensor_key:
+            return metric._value
+    return None
+
+def get_link_local_interface():
+    cdc_ether_path = "/sys/bus/usb/drivers/cdc_ether"
+    for ether in os.listdir(cdc_ether_path):
+        concrete_ether = os.path.join(cdc_ether_path, ether)
+        if os.path.isdir(concrete_ether):
+            concrete_ether_net = os.path.join(concrete_ether, 'net')
+            if os.path.exists(concrete_ether_net):
+                return os.listdir(concrete_ether_net)[0]
+
+def get_link_local_address(link_local_interface):
+    for addr in ifaddresses(link_local_interface)[AF_INET6]:
+        address = addr['addr'].split('%')[0]
+        # according to rfc4291 this ipv6 address is used for link local connection
+        if address.startswith('fe80:'):
+            # first address is taken for BMC and second for this host
+            return address[:-1] + '1'
+    return None
+
+def get_psu_metrics():
+    link_local_interface = get_link_local_interface()
+    link_local_address = get_link_local_address(link_local_interface)
+
+    http_address = "http://[%s%%%s]:8080" % (link_local_address, link_local_interface)
+    args = "/api/sys/bmc/sensors/%20-A%20-u%20"
+    cmd = "curl " + http_address + args
+    output = Popen(cmd.split(), stdout=PIPE, stderr=DEVNULL).stdout.read()
+    output = json.loads(output.decode())["Information"]["Description"][0].strip()
+    sections = output.split("\n\n")
+
+    metrics = []
+    # iterating through drivers and their sensors
+    for section in sections:
+        fields = section.split("\n")
+
+        label = None
+        # iterating through sensors and their inputs
+        for field in fields[1:]: # skipping driver name
+            # parsing input sensor
+            if field.startswith("  "):
+                field = field.replace("  ", "")
+                # split sensor into name and value
+                field_key, field_value = field.split(": ")
+                if "_" in field_key:
+                    sensor_id, sensor_key = field_key.split("_", 1)
+                    if sensor_key == "input":
+                        if sensor_id.startswith("temp"):
+                            metrics.append(
+                                Temperature(sensor_id, sensor_key, field_value, label=label))
+                        elif sensor_id.startswith("in"):
+                            metrics.append(
+                                Voltage(sensor_id, sensor_key, field_value, label=label))
+                        elif sensor_id.startswith("power"):
+                            metrics.append(
+                                Power(sensor_id, sensor_key, field_value, label=label))
+                        elif sensor_id.startswith("curr"):
+                            metrics.append(
+                                Current(sensor_id, sensor_key, field_value, label=label))
+                        elif sensor_id.startswith("fan"):
+                            metrics.append(
+                                FanRpm(sensor_id, sensor_key, field_value, label=label))
+                    elif sensor_key == "fault":
+                        if sensor_id.startswith("fan"):
+                            metrics.append(
+                                FanFault(sensor_id, sensor_key, field_value, label=label))
+            elif field.startswith("ERROR"):
+                syslog.syslog(syslog.LOG_INFO, field)
+            else:
+                label = field[:-1]  # strip off trailing ":" character
+
+    return metrics

platform/barefoot/sonic-platform-modules-bfn-montara/sonic_platform/psu.py

@@ -6,6 +6,8 @@ try:
     import time
     import signal
     import syslog
+    import logging
+    import threading
 
     sys.path.append(os.path.dirname(__file__))
 
@@ -14,12 +16,18 @@ try:
     from sonic_platform_base.psu_base import PsuBase
     from sonic_platform.thermal import psu_thermals_list_get
     from platform_utils import cancel_on_sigterm
+    from sonic_platform.bfn_extensions.psu_sensors import get_psu_metrics
+    from sonic_platform.bfn_extensions.psu_sensors import get_metric_value
 except ImportError as e:
     raise ImportError (str(e) + "- required module not found")
 
 class Psu(PsuBase):
     """Platform-specific PSU class"""
 
+    __lock = threading.Lock()
+    __sensors_info = None
+    __timestamp = 0
+
     sigterm = False
     sigterm_default_handler = None
     cls_inited = False
@@ -48,6 +56,20 @@ class Psu(PsuBase):
         syslog.syslog(syslog.LOG_INFO, "Canceling PSU platform API calls...")
         cls.sigterm = True
 
+    @classmethod
+    def __sensors_get(cls, cached=True):
+        cls.__lock.acquire()
+        if time.time() > cls.__timestamp + 15:
+            # Update cache once per 15 seconds
+            try:
+                cls.__sensors_info = get_psu_metrics()
+                cls.__timestamp = time.time()
+            except Exception as e:
+                logging.warning("Failed to update sensors cache: " + str(e))
+        info = cls.__sensors_info
+        cls.__lock.release()
+        return info
+
     '''
     Units of returned info object values:
         vin - V
@@ -105,8 +127,7 @@ class Psu(PsuBase):
             A float number, the output voltage in volts,
             e.g. 12.1
         """
-        info = self.__info_get()
-        return float(info.vout) if info else 0
+        return get_metric_value(Psu.__sensors_get(), "PSU%d 12V Output Voltage_in1_input" % self.__index)
 
     def get_current(self):
         """
@@ -115,8 +136,24 @@ class Psu(PsuBase):
         Returns:
             A float number, the electric current in amperes, e.g 15.4
         """
-        info = self.__info_get()
-        return info.iout / 1000 if info else 0
+        return get_metric_value(Psu.__sensors_get(), "PSU%d 12V Output Current_curr2_input" % self.__index)
+
+    def get_input_voltage(self):
+        """
+        Retrieves current PSU voltage input
+        Returns:
+            A float number, the input voltage in volts,
+            e.g. 220
+        """
+        return get_metric_value(Psu.__sensors_get(), "PSU%d Input Voltage_in0_input" % self.__index)
+
+    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 0.8
+        """
+        return get_metric_value(Psu.__sensors_get(), "PSU%d Input Current_curr1_input" % self.__index)
 
     def get_power(self):
         """