platform: arm64: add Huawei Matebook E Go EC driver

There are three variants of which Huawei released the first two
simultaneously.

Huawei Matebook E Go LTE(sc8180x), codename seems to be gaokun2.
Huawei Matebook E Go([email protected]), codename must be gaokun3. (see [1])
Huawei Matebook E Go 2023([email protected]), codename should be also gaokun3.

Adding support for the latter two variants for now, this driver should
also work for the sc8180x variant according to acpi table files, but I
don't have the device to test yet.

Different from other Qualcomm Snapdragon sc8280xp based machines, the
Huawei Matebook E Go uses an embedded controller while others use
a system called PMIC GLink. This embedded controller can be used to
perform a set of various functions, including, but not limited to:

- Battery and charger monitoring;
- Charge control and smart charge;
- Fn_lock settings;
- Tablet lid status;
- Temperature sensors;
- USB Type-C notifications (ports orientation,  DP alt mode HPD);
- USB Type-C PD (according to observation, up to 48w).

Add a driver for the EC which creates devices for UCSI and power supply
devices.

This driver is inspired by the following drivers:
        drivers/platform/arm64/acer-aspire1-ec.c
        drivers/platform/arm64/lenovo-yoga-c630.c
        drivers/platform/x86/huawei-wmi.c

Also thanks for reviewers' working. They have made this patch improve
a lot.

[1] https://bugzilla.kernel.org/show_bug.cgi?id=219645

Signed-off-by: Pengyu Luo <[email protected]>
Reviewed-by: Ilpo Järvinen <[email protected]>
Link: https://lore.kernel.org/r/[email protected]
Signed-off-by: Ilpo Järvinen <[email protected]>

Author: right-0903

MAINTAINERS

@@ -10698,6 +10698,13 @@ S:	Maintained
 F:	Documentation/networking/device_drivers/ethernet/huawei/hinic.rst
 F:	drivers/net/ethernet/huawei/hinic/
 
+HUAWEI MATEBOOK E GO EMBEDDED CONTROLLER DRIVER
+M:	Pengyu Luo <[email protected]>
+S:	Maintained
+F:	Documentation/devicetree/bindings/platform/huawei,gaokun-ec.yaml
+F:	drivers/platform/arm64/huawei-gaokun-ec.c
+F:	include/linux/platform_data/huawei-gaokun-ec.h
+
 HUGETLB SUBSYSTEM
 M:	Muchun Song <[email protected]>
 L:	[email protected]

drivers/platform/arm64/Kconfig

@@ -33,6 +33,27 @@ config EC_ACER_ASPIRE1
 	  laptop where this information is not properly exposed via the
 	  standard ACPI devices.
 
+config EC_HUAWEI_GAOKUN
+	tristate "Huawei Matebook E Go Embedded Controller driver"
+	depends on ARCH_QCOM || COMPILE_TEST
+	depends on I2C
+	depends on INPUT
+	depends on HWMON
+	select AUXILIARY_BUS
+
+	help
+	  Say Y here to enable the EC driver for the Huawei Matebook E Go
+	  which is a sc8280xp-based 2-in-1 tablet. The driver handles battery
+	  (information, charge control) and USB Type-C DP HPD events as well
+	  as some misc functions like the lid sensor and temperature sensors,
+	  etc.
+
+	  This driver provides battery and AC status support for the mentioned
+	  laptop where this information is not properly exposed via the
+	  standard ACPI devices.
+
+	  Say M or Y here to include this support.
+
 config EC_LENOVO_YOGA_C630
 	tristate "Lenovo Yoga C630 Embedded Controller driver"
 	depends on ARCH_QCOM || COMPILE_TEST

drivers/platform/arm64/Makefile

@@ -6,4 +6,5 @@
 #
 
 obj-$(CONFIG_EC_ACER_ASPIRE1)	+= acer-aspire1-ec.o
+obj-$(CONFIG_EC_HUAWEI_GAOKUN)	+= huawei-gaokun-ec.o
 obj-$(CONFIG_EC_LENOVO_YOGA_C630) += lenovo-yoga-c630.o