power: supply: Add Spreadtrum SC27XX fuel gauge unit driver

This patch adds the Spreadtrum SC27XX serial PMICs fuel gauge support,
which is used to calculate the battery capacity.
Original-by: Yuanjiang Yu <yuanjiang.yu@unisoc.com>
Signed-off-by: Baolin Wang <baolin.wang@linaro.org>
Acked-by: Linus Walleij <linus.walleij@linaro.org>
Signed-off-by: Sebastian Reichel <sebastian.reichel@collabora.com>

drivers/power/supply/Kconfig

@@ -652,4 +652,11 @@ config CHARGER_SC2731
 	 Say Y here to enable support for battery charging with SC2731
 	 PMIC chips.
 
+config FUEL_GAUGE_SC27XX
+	tristate "Spreadtrum SC27XX fuel gauge driver"
+	depends on MFD_SC27XX_PMIC || COMPILE_TEST
+	help
+	 Say Y here to enable support for fuel gauge with SC27XX
+	 PMIC chips.
+
 endif # POWER_SUPPLY

drivers/power/supply/Makefile

@@ -86,3 +86,4 @@ obj-$(CONFIG_AXP288_FUEL_GAUGE) += axp288_fuel_gauge.o
 obj-$(CONFIG_AXP288_CHARGER)	+= axp288_charger.o
 obj-$(CONFIG_CHARGER_CROS_USBPD)	+= cros_usbpd-charger.o
 obj-$(CONFIG_CHARGER_SC2731)	+= sc2731_charger.o
+obj-$(CONFIG_FUEL_GAUGE_SC27XX)	+= sc27xx_fuel_gauge.o