This repo is an implementation of the android.hardware.health HAL, based on the official guide and existing device-specific implementations.
It was written for Sony devices from 2016 onward, but it should work on other
devices with a few small modifications as well.
Most notably, the sysfs paths might be different and the persist partition might
be mounted at /persist instead of /mnt/vendor/persist.
Apache License version 2, see LICENSE.txt.
To start using this HAL, you need to do the following:
Add the HAL to the vendor device manifest.
For SODP, that file is in device-sony-common/vintf/manifest.xml.
<hal format="hidl">
<name>android.hardware.health</name>
<transport>hwbinder</transport>
<version>2.0</version>
<interface>
<name>IHealth</name>
<instance>default</instance>
</interface>
</hal>
Add android.hardware.health@2.0-service-.sony to PRODUCT_PACKAGES and remove
the obsolete backup healthd instance that is shipped by default.
For SODP, that is done in common-treble.mk:
# Health (in addition to own board libhealth)
PRODUCT_PACKAGES += \
android.hardware.health@2.0-service.sony
# Remove deprecated backup healthd
DEVICE_FRAMEWORK_MANIFEST_FILE += \
system/libhidl/vintfdata/manifest_healthd_exclude.xml
Add the binary to sepolicy file_contexts:
/(system/vendor|vendor)/bin/hw/android\.hardware\.health@2\.0-service\.sony u:object_r:hal_health_default_exec:s0
And allow vendor_init to create the /mnt/vendor/persist/battery/ folder.
# vendor_init.te:
allow vendor_init persist_battery_file:dir create_dir_perms;
Many features of this HAL were taken from the Pixel family of devices. Marlin(Pixel 1), Wahoo(Pixel 2) and Crosshatch(Pixel 3) all have more or less the same implementation. We don't need to do quite as much logging as they do, so Pixelstats-related functions have been stripped out.
Another difference are the battery cycles: The pixel battery driver is able to
report cycles for 8 individual "bins" for what are presumably groups/blocks of
battery cells instead of one single cycle count. If your device supports those
"bins" as well, take a look at the pixel CycleCountBackupRestore
implementation.
Relevant files and folders:
- system/core/healthd/
- hardware/interfaces/health/2.0/
- frameworks/native/services/batteryservice/include/batteryservice/BatteryService.h
- frameworks/native/services/sensorservice/BatteryService.h
- For the wakeup timers:
- frameworks/base/services/core/java/com/android/server/am/ActivityManagerService.java
- frameworks/base/services/core/jni/com_android_server_AlarmManagerService.cpp
- kernel: fs/timerfd.c for timerfd_create() from healthd_common.cpp, included through the android.hardware.health@2.0-impl shared_lib
- SoC = State of Charge, e.g. from 0-100% (n.b. "SoC" is normally understood to mean "System-on-chip")
- FG = Fuel Gauge, similar to SoC
- BMS = Battery Management System
USB terms
- SDP = Standard downstream port(2.5-500mA)
- CDP = Charging downstream port(up to 1500mA)
- DCP = Dedicated charging port(up to 1500mA)
Type-C terms:
- UFP = "Upstream-facing port", i.e. the port that flows towards the computer
- DFP = "Downstream-facing port", i.e. the port that flows from the device towards another device, perhaps USB audio output
Internals:
- CC/CV = Constant current / constant voltage (CC/CV) For lithium batteries: When nearly depleted, use constant current for charging. When approaching max voltage, use contant voltage.
- OCV = Open circuit voltage
- CC = Coulomb counter
- PMIC = Power Management Integrated Circuit
- SPMI = System Power Management Interface
- FCC = Full charge capacity