leds: rgb: mt6370: Add MediaTek MT6370 current sink type LED Indicator support

The MediaTek MT6370 is a highly-integrated smart power management IC,
which includes a single cell Li-Ion/Li-Polymer switching battery
charger, a USB Type-C & Power Delivery (PD) controller, dual
Flash LED current sources, a RGB LED driver, a backlight WLED driver,
a display bias driver and a general LDO for portable devices.

Add support for the MediaTek MT6370 Current Sink Type LED Indicator
driver. It can control four channels current-sink RGB LEDs with 3 modes:
constant current, PWM, and breath mode.

Co-developed-by: Alice Chen <alice_chen@richtek.com>
Signed-off-by: Alice Chen <alice_chen@richtek.com>
Signed-off-by: ChiYuan Huang <cy_huang@richtek.com>
Signed-off-by: ChiaEn Wu <chiaen_wu@richtek.com>
Acked-by: Jacek Anaszewski <jacek.anaszewski@gmail.com>
Signed-off-by: Lee Jones <lee@kernel.org>
Link: https://lore.kernel.org/r/1df93a583c3f508a7158b83b95857e9bce235e1b.1678430444.git.chiaen_wu@richtek.com

drivers/leds/rgb/Kconfig

@@ -26,4 +26,17 @@ config LEDS_QCOM_LPG
 
 	  If compiled as a module, the module will be named leds-qcom-lpg.
 
+config LEDS_MT6370_RGB
+	tristate "LED Support for MediaTek MT6370 PMIC"
+	depends on MFD_MT6370
+	select LINEAR_RANGE
+	help
+	  Say Y here to enable support for MT6370_RGB LED device.
+	  In MT6370, there are four channel current-sink LED drivers that
+	  support hardware pattern for constant current, PWM, and breath mode.
+	  Isink4 channel can also be used as a CHG_VIN power good indicator.
+
+	  This driver can also be built as a module. If so, the module
+	  will be called "leds-mt6370-rgb".
+
 endif # LEDS_CLASS_MULTICOLOR

drivers/leds/rgb/Makefile

@@ -2,3 +2,4 @@
 
 obj-$(CONFIG_LEDS_PWM_MULTICOLOR)	+= leds-pwm-multicolor.o
 obj-$(CONFIG_LEDS_QCOM_LPG)		+= leds-qcom-lpg.o
+obj-$(CONFIG_LEDS_MT6370_RGB)		+= leds-mt6370-rgb.o