Add LTC2941/LTC2943 Battery Gauge Driver

Both the LTC2941 and LTC2943 measure battery capacity.
The LTC2943 is compatible with the LTC2941, it adds voltage and
temperature monitoring, and uses a slightly different conversion
formula for the charge counter.

To avoid confusion with e.g. the LTC2945, the driver is called
LTC2941 instead of LTC294X.

v2: Fix units of measurement: uV, uA and centidegrees.
v3: Correctly set configuration register. Allow negative values
    for the sense resistor.
v4: Run checkpatch.pl and fix all errors and warnings.
v5: Prefix "lltc," to devicetree properties.
Signed-off-by: Mike Looijmans <mike.looijmans@topic.nl>
[ removed .owner field ]
Signed-off-by: Sebastian Reichel <sre@kernel.org>

drivers/power/Kconfig

@@ -388,6 +388,14 @@ config CHARGER_TPS65090
 	 Say Y here to enable support for battery charging with TPS65090
 	 PMIC chips.
 
+config BATTERY_GAUGE_LTC2941
+	tristate "LTC2941/LTC2943 Battery Gauge Driver"
+	depends on I2C
+	help
+	  Say Y here to include support for LTC2941 and LTC2943 Battery
+	  Gauge IC. The driver reports the charge count continuously, and
+	  measures the voltage and temperature every 10 seconds.
+
 config AB8500_BM
 	bool "AB8500 Battery Management Driver"
 	depends on AB8500_CORE && AB8500_GPADC

drivers/power/Makefile

@@ -20,6 +20,7 @@ obj-$(CONFIG_BATTERY_DS2760)	+= ds2760_battery.o
 obj-$(CONFIG_BATTERY_DS2780)	+= ds2780_battery.o
 obj-$(CONFIG_BATTERY_DS2781)	+= ds2781_battery.o
 obj-$(CONFIG_BATTERY_DS2782)	+= ds2782_battery.o
+obj-$(CONFIG_BATTERY_GAUGE_LTC2941)	+= ltc2941-battery-gauge.o
 obj-$(CONFIG_BATTERY_GOLDFISH)	+= goldfish_battery.o
 obj-$(CONFIG_BATTERY_PMU)	+= pmu_battery.o
 obj-$(CONFIG_BATTERY_OLPC)	+= olpc_battery.o