instrument/battery_monitor: Add initial draft for battery monitor

Attempt to estimate energy usage from the builtin voltage and current
reported values.
Note that the device must not be charging while in use.

devlib/instrument/battery_monitor.py

@@ -0,0 +1,202 @@
+#    Copyright 2021 ARM Limited
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#     http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+#
+from __future__ import division
+
+import logging
+import re
+import sys
+import tempfile
+import threading
+import time
+
+from devlib.instrument import Instrument, MeasurementsCsv, CONTINUOUS
+from devlib.exception import TargetStableError, TargetNotRespondingError, WorkerThreadError
+from devlib.utils.csvutil import csvreader, csvwriter
+
+
+logger = logging.getLogger('BattryMonitor')
+
+
+BATTERY_STATS_REGEX = re.compile(r'level: (?P<level>\d+).*scale: (?P<scale>\d+).*voltage: (?P<voltage>\d+)', flags=re.DOTALL)
+
+
+# List of SysFS node for current taken from Ampere Application
+# https://forum.xda-developers.com/t/app-4-0-3-ampere-current-meter.3040329/post-59086006
+CURRENT_SYSFS_NODES = [
+    '/sys/class/power_supply/ab8500_fg/current_now',
+    '/sys/class/power_supply/android-battery/current_now',
+    '/sys/class/power_supply/battery/batt_attr_text',
+    '/sys/class/power_supply/battery/batt_chg_current',
+    '/sys/class/power_supply/battery/batt_current',
+    '/sys/class/power_supply/battery/batt_current_adc',
+    '/sys/class/power_supply/battery/batt_current_now',
+    '/sys/class/power_supply/battery/BatteryAverageCurrent',
+    '/sys/class/power_supply/battery/charger_current',
+    '/sys/class/power_supply/battery/current_avg',
+    '/sys/class/power_supply/battery/current_max',
+    '/sys/class/power_supply/battery/current_now',
+    '/sys/class/power_supply/Battery/current_now',
+    '/sys/class/power_supply/battery/smem_text',
+    '/sys/class/power_supply/bq27520/current_now',
+    '/sys/class/power_supply/da9052-bat/current_avg',
+    '/sys/class/power_supply/ds2784-fuelgauge/current_now',
+    '/sys/class/power_supply/max17042-0/current_now',
+    '/sys/class/power_supply/max170xx_battery/current_now',
+    '/sys/devices/platform/battery/power_supply/battery/BatteryAverageCurrent',
+    '/sys/devices/platform/cpcap_battery/power_supply/usb/current_now',
+    '/sys/devices/platform/ds2784-battery/getcurrent',
+    '/sys/devices/platform/i2c-adapter/i2c-0/0-0036/power_supply/battery/current_now',
+    '/sys/devices/platform/i2c-adapter/i2c-0/0-0036/power_supply/ds2746-battery/current_now',
+    '/sys/devices/platform/msm-charger/power_supply/battery_gauge/current_now',
+    '/sys/devices/platform/mt6320-battery/power_supply/battery/BatteryAverageCurrent',
+    '/sys/devices/platform/mt6329-battery/FG_Battery_CurrentConsumption',
+    '/sys/EcControl/BatCurrent',
+]
+
+
+class BatteryMonitorInstrument(Instrument):
+
+    name = 'battey_monitor'
+    mode = CONTINUOUS
+
+    def __init__(self, target, period=2, current_scale=1e6,
+                 voltage_scale=1e3, current_node=None,):
+
+        if not target.is_rooted:
+            self.logger.warn('Target is not rooted, current readings are likely to fail.')
+        super(BatteryMonitorInstrument, self).__init__(target)
+
+        self.period = period
+        self.target = target
+
+        self.logger.debug('Discovering available current sysfs node..')
+        self.current_node, inverse = self._discover_current_node(current_node)
+
+        # sensor kind --> unit conversion
+        self.value_convert = {
+            'voltage': lambda x: int(x) / voltage_scale,
+            'current': lambda x: (-int(x) if inverse else int(x)) / current_scale,
+            'power': lambda x: -int(x) / (voltage_scale * current_scale),
+            'percent': lambda x: float(x),
+            'time': lambda x: x,
+        }
+
+        self.add_channel('battery', 'voltage')
+        self.add_channel('battery', 'current')
+        self.add_channel('battery', 'power')
+        self.add_channel('battery', 'percent')
+        self.add_channel('timestamp', 'time')
+
+    def reset(self, sites=None, kinds=None, channels=None):
+        super(BatteryMonitorInstrument, self).reset(sites, kinds, channels)
+        self.raw_data_file = tempfile.mkstemp('.csv')[1]
+        self.collector = BatteryStatsCollector(self.target,
+                                               self.period,
+                                               self.current_node,
+                                               self.raw_data_file)
+
+    def start(self):
+        if not self.collector:
+            raise RuntimeError('Must call "reset" before "start"')
+        self.collector.start()
+
+    def stop(self):
+        self.collector.stop()
+
+    def _discover_current_node(self, current_node):
+        paths = [current_node] if current_node else CURRENT_SYSFS_NODES
+        for path in paths:
+            try:
+                reading = self.target.read_int(path)
+            except TargetStableError:
+                continue
+            if reading:
+                self.logger.debug('Found current sysfs node at: {}'.format(path))
+                # Return if the value reported is negative or positive, assuming
+                # device is currently discharging
+                return path, reading < 0
+
+        raise RuntimeError('Failed to detect valid reading from known current nodes.')
+
+
+    def get_data(self, outfile):
+        all_channels = self.list_channels()
+        channels_labels = [c.label for c in all_channels]
+        active_channels = [c.label for c in self.active_channels]
+        active_indexes = [channels_labels.index(ac) for ac in active_channels]
+
+        with csvreader(self.raw_data_file, skipinitialspace=True) as reader:
+            with csvwriter(outfile) as writer:
+                writer.writerow(active_channels)
+                for row in reader:
+                    output_row = [self.value_convert[all_channels[i].kind](row[i]) for i in active_indexes]
+                    writer.writerow(output_row)
+
+        return MeasurementsCsv(outfile, self.active_channels, 1/self.period)
+
+
+class BatteryStatsCollector(threading.Thread):
+
+    def __init__(self, target, period, current_node, raw_data_file):
+        super(BatteryStatsCollector, self).__init__()
+        self.target = target
+        self.period = period
+        self.current_node = current_node
+        self.raw_data_file = raw_data_file
+        self.stop_signal = threading.Event()
+        self.measurements = []
+        self.exc = None
+
+    def run(self):
+        logger.debug('Battery stats collection started.')
+        try:
+            self.stop_signal.clear()
+            logger.debug('Using temp file: {}'.format(self.raw_data_file))
+            wfh = open(self.raw_data_file, 'wb')
+            try:
+                while not self.stop_signal.is_set():
+                    self.collect_stats(wfh)
+                    time.sleep(self.period)
+            finally:
+                wfh.close()
+        except (TargetNotRespondingError, TimeoutError):
+            raise
+        except Exception as e:
+            logger.warning('Exception on collector thread: {}({})'.format(e.__class__.__name__, e))
+            self.exc = WorkerThreadError(self.name, sys.exc_info())
+        logger.debug('Battery stats collection stopped.')
+
+    def collect_stats(self, wfh):
+        voltage, batt_pct = self._get_battery_stats()
+        current = self._measure_current()
+        power = voltage * current
+        results = ','.join(map(str, [voltage, current, power, batt_pct, time.time()]))
+        wfh.write('{}\n'.format(results).encode('utf-8'))
+
+    def _get_battery_stats(self):
+        output = self.target.execute('dumpsys battery')
+        match = BATTERY_STATS_REGEX.search(output)
+        voltage = int(match.group('voltage'))
+        batt_pct = (int(match.group('level'))*100)/int(match.group('scale'))
+        return voltage, batt_pct
+
+    def _measure_current(self):
+        return self.target.read_int(self.current_node)
+
+    def stop(self):
+        self.stop_signal.set()
+        self.join()
+        if self.exc:
+            raise self.exc  # pylint: disable=E0702