power/supply: Add ltc4162-l-charger

Add support for the LTC4162-L Li-Ion battery charger. The driver allows
reading back telemetry and to set some charging options like the input
current limit.
Signed-off-by: Mike Looijmans <mike.looijmans@topic.nl>
Signed-off-by: Sebastian Reichel <sebastian.reichel@collabora.com>

Documentation/ABI/testing/sysfs-class-power-ltc4162l

+What:		/sys/class/power_supply/ltc4162-l/charge_status
+Date:		Januari 2021
+KernelVersion:	5.11
+Description:
+		Detailed charge status information as reported by the chip.
+
+		Access: Read
+
+		Valid values:
+			ilim_reg_active
+			thermal_reg_active
+			vin_uvcl_active
+			iin_limit_active
+			constant_current
+			constant_voltage
+			charger_off
+
+What:		/sys/class/power_supply/ltc4162-l/ibat
+Date:		Januari 2021
+KernelVersion:	5.11
+Description:
+		Battery input current as measured by the charger. Negative value
+		means that the battery is discharging.
+
+		Access: Read
+
+		Valid values: Signed value in microamps
+
+What:		/sys/class/power_supply/ltc4162-l/vbat
+Date:		Januari 2021
+KernelVersion:	5.11
+Description:
+		Battery voltage as measured by the charger.
+
+		Access: Read
+
+		Valid values: In microvolts
+
+What:		/sys/class/power_supply/ltc4162-l/vbat_avg
+Date:		Januari 2021
+KernelVersion:	5.11
+Description:
+		Battery voltage, averaged over time, as measured by the charger.
+
+		Access: Read
+
+		Valid values: In microvolts
+
+What:		/sys/class/power_supply/ltc4162-l/force_telemetry
+Date:		Januari 2021
+KernelVersion:	5.11
+Description:
+		To save battery current, the measurement system is disabled if
+		the battery is the only source of power. This affects all
+		voltage, current and temperature measurements.
+		Write a "1" to this to keep performing telemetry once every few
+		seconds, even when running on battery (as reported by the online
+		property, which is "1" when external power is available and "0"
+		when the system runs on battery).
+
+		Access: Read, Write
+
+		Valid values: 0 (disabled) or 1 (enabled)
+
+What:		/sys/class/power_supply/ltc4162-l/arm_ship_mode
+Date:		Januari 2021
+KernelVersion:	5.11
+Description:
+		The charger will normally drain the battery while inactive,
+		typically drawing about 54 microamps. Write a "1" to this
+		property to arm a special "ship" mode that extends shelf life
+		by reducing the leakage to about 2.8 microamps. The chip will
+		remain in this mode (and no longer respond to I2C commands)
+		until some external power-supply is attached raising the input
+		voltage above 1V. It will then automatically revert to "0".
+		Writing a "0" to the property cancels the "ship" mode request.
+		The ship mode, when armed, activates once the input voltage
+		drops below 1V.
+
+		Access: Read, Write
+
+		Valid values: 0 (disable) or 1 (enable)

drivers/power/supply/Kconfig

@@ -513,6 +513,14 @@ config CHARGER_LT3651
 	  Say Y to include support for the Analog Devices (Linear Technology)
 	  LT3651 battery charger which reports its status via GPIO lines.
 
+config CHARGER_LTC4162L
+	tristate "LTC4162-L charger"
+	depends on I2C
+	select REGMAP_I2C
+	help
+	  Say Y to include support for the Analog Devices (Linear Technology)
+	  LTC4162-L battery charger connected to I2C.
+
 config CHARGER_MAX14577
 	tristate "Maxim MAX14577/77836 battery charger driver"
 	depends on MFD_MAX14577

drivers/power/supply/Makefile

@@ -70,6 +70,7 @@ obj-$(CONFIG_CHARGER_LP8788)	+= lp8788-charger.o
 obj-$(CONFIG_CHARGER_GPIO)	+= gpio-charger.o
 obj-$(CONFIG_CHARGER_MANAGER)	+= charger-manager.o
 obj-$(CONFIG_CHARGER_LT3651)	+= lt3651-charger.o
+obj-$(CONFIG_CHARGER_LTC4162L)	+= ltc4162-l-charger.o
 obj-$(CONFIG_CHARGER_MAX14577)	+= max14577_charger.o
 obj-$(CONFIG_CHARGER_DETECTOR_MAX14656)	+= max14656_charger_detector.o
 obj-$(CONFIG_CHARGER_MAX77650)	+= max77650-charger.o