platform/x86: Support for EC-connected GPIOs for identify LED/button on Barco P50 board

Add a driver providing access to the GPIOs for the identify button and led
present on Barco P50 board, based on the pcengines-apuv2.c driver.

There is unfortunately no suitable ACPI entry for the EC communication
interface, so instead bind to boards with "P50" as their DMI product family
and hard code the I/O port number (0x299).

The driver also hooks up the leds-gpio and gpio-keys-polled drivers to the
GPIOs, so they are finally exposed as:

LED:
/sys/class/leds/identify

Button: (/proc/bus/input/devices)
I: Bus=0019 Vendor=0001 Product=0001 Version=0100
N: Name="identify"
P: Phys=gpio-keys-polled/input0
S: Sysfs=/devices/platform/barco-p50-gpio/gpio-keys-polled/input/input10
U: Uniq=
H: Handlers=event10
B: PROP=0
B: EV=3
B: KEY=1000000 0 0 0 0 0 0

Signed-off-by: Santosh Kumar Yadav <[email protected]>
Signed-off-by: Peter Korsgaard <[email protected]>
Link: https://lore.kernel.org/r/[email protected]
Reviewed-by: Hans de Goede <[email protected]>
Signed-off-by: Hans de Goede <[email protected]>

Author: Santosh Kumar Yadav

MAINTAINERS

@@ -3215,6 +3215,12 @@ F:	drivers/video/backlight/
 F:	include/linux/backlight.h
 F:	include/linux/pwm_backlight.h
 
+BARCO P50 GPIO DRIVER
+M:	Santosh Kumar Yadav <[email protected]>
+M:	Peter Korsgaard <[email protected]>
+S:	Maintained
+F:	drivers/platform/x86/barco-p50-gpio.c
+
 BATMAN ADVANCED
 M:	Marek Lindner <[email protected]>
 M:	Simon Wunderlich <[email protected]>

drivers/platform/x86/Kconfig

@@ -729,6 +729,16 @@ config PCENGINES_APU2
 	  To compile this driver as a module, choose M here: the module
 	  will be called pcengines-apuv2.
 
+config BARCO_P50_GPIO
+	tristate "Barco P50 GPIO driver for identify LED/button"
+	depends on GPIOLIB
+	help
+	  This driver provides access to the GPIOs for the identify button
+	  and led present on Barco P50 board.
+
+	  To compile this driver as a module, choose M here: the module
+	  will be called barco-p50-gpio.
+
 config SAMSUNG_LAPTOP
 	tristate "Samsung Laptop driver"
 	depends on RFKILL || RFKILL = n

drivers/platform/x86/Makefile

@@ -81,6 +81,9 @@ obj-$(CONFIG_XO1_RFKILL)	+= xo1-rfkill.o
 # PC Engines
 obj-$(CONFIG_PCENGINES_APU2)	+= pcengines-apuv2.o
 
+# Barco
+obj-$(CONFIG_BARCO_P50_GPIO)	+= barco-p50-gpio.o
+
 # Samsung
 obj-$(CONFIG_SAMSUNG_LAPTOP)	+= samsung-laptop.o
 obj-$(CONFIG_SAMSUNG_Q10)	+= samsung-q10.o