platform/x86: Add LG Gram laptop special features driver

A driver for LG Gram laptop supporting features not available through the
standard interfaces:

- Support for the 5 Fn keys that generate ACPI or WMI events.

- Two software controlled LEDs: keyboard backlight (also controlled by
  hardware) and touchpad LED.

- Extra features: reader mode, Fn lock, cooling mode, USB charge mode, and
  maximal battery charging level.
Signed-off-by: Matan Ziv-Av <matan@svgalib.org>
Signed-off-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>

Documentation/ABI/testing/sysfs-platform-lg-laptop

+What:		/sys/devices/platform/lg-laptop/reader_mode
+Date:		October 2018
+KernelVersion:	4.20
+Contact:	"Matan Ziv-Av <matan@svgalib.org>
+Description:
+        Control reader mode. 1 means on, 0 means off.
+
+What:		/sys/devices/platform/lg-laptop/fn_lock
+Date:		October 2018
+KernelVersion:	4.20
+Contact:	"Matan Ziv-Av <matan@svgalib.org>
+Description:
+        Control FN lock mode. 1 means on, 0 means off.
+
+What:		/sys/devices/platform/lg-laptop/battery_care_limit
+Date:		October 2018
+KernelVersion:	4.20
+Contact:	"Matan Ziv-Av <matan@svgalib.org>
+Description:
+        Maximal battery charge level. Accepted values are 80 or 100.
+
+What:		/sys/devices/platform/lg-laptop/fan_mode
+Date:		October 2018
+KernelVersion:	4.20
+Contact:	"Matan Ziv-Av <matan@svgalib.org>
+Description:
+        Control fan mode. 1 for performance mode, 0 for silent mode.
+
+What:		/sys/devices/platform/lg-laptop/usb_charge
+Date:		October 2018
+KernelVersion:	4.20
+Contact:	"Matan Ziv-Av <matan@svgalib.org>
+Description:
+        Control USB port charging when device is turned off.
+        1 means on, 0 means off.

Documentation/laptops/lg-laptop.rst

+.. SPDX-License-Identifier: GPL-2.0+
+LG Gram laptop extra features
+=============================
+
+By Matan Ziv-Av <matan@svgalib.org>
+
+
+Hotkeys
+-------
+
+The following FN keys are ignored by the kernel without this driver:
+- FN-F1 (LG control panel)   - Generates F15
+- FN-F5 (Touchpad toggle)    - Generates F13
+- FN-F6 (Airplane mode)      - Generates RFKILL
+- FN-F8 (Keyboard backlight) - Generates F16.
+  This key also changes keyboard backlight mode.
+- FN-F9 (Reader mode)        - Generates F14
+
+The rest of the FN key work without a need for a special driver.
+
+
+Reader mode
+-----------
+
+Writing 0/1 to /sys/devices/platform/lg-laptop/reader_mode disables/enables
+reader mode. In this mode the screen colors change (blue color reduced),
+and the reader mode indicator LED (on F9 key) turns on.
+
+
+FN Lock
+-------
+
+Writing 0/1 to /sys/devices/platform/lg-laptop/fn_lock disables/enables
+FN lock.
+
+
+Battery care limit
+------------------
+
+Writing 80/100 to /sys/devices/platform/lg-laptop/battery_care_limit
+sets the maximum capacity to charge the battery. Limiting the charge
+reduces battery capacity loss over time.
+
+This value is reset to 100 when the kernel boots.
+
+
+Fan mode
+--------
+
+Writing 1/0 to /sys/devices/platform/lg-laptop/fan_mode disables/enables
+the fan silent mode.
+
+
+USB charge
+----------
+
+Writing 0/1 to /sys/devices/platform/lg-laptop/usb_charge disables/enables
+charging another device from the USB port while the device is turned off.
+
+This value is reset to 0 when the kernel boots.
+
+
+LEDs
+~~~~
+
+The are two LED devices supported by the driver:
+
+Keyboard backlight
+------------------
+
+A led device named kbd_led controls the keyboard backlight. There are three
+lighting level: off (0), low (127) and high (255).
+
+The keyboard backlight is also controlled by the key combination FN-F8
+which cycles through those levels.
+
+
+Touchpad indicator LED
+----------------------
+
+On the F5 key. Controlled by led device names tpad_led.

MAINTAINERS

@@ -8231,6 +8231,14 @@ W:	http://legousb.sourceforge.net/
 S:	Maintained
 F:	drivers/usb/misc/legousbtower.c
 
+LG LAPTOP EXTRAS
+M:	Matan Ziv-Av <matan@svgalib.org>
+L:	platform-driver-x86@vger.kernel.org
+S:	Maintained
+F:	Documentation/ABI/testing/sysfs-platform-lg-laptop
+F:	Documentation/laptops/lg-laptop.rst
+F:	drivers/platform/x86/lg-laptop.c
+
 LG2160 MEDIA DRIVER
 M:	Michael Krufky <mkrufky@linuxtv.org>
 L:	linux-media@vger.kernel.org

drivers/platform/x86/Kconfig

@@ -367,6 +367,20 @@ config HP_WMI
 	 To compile this driver as a module, choose M here: the module will
 	 be called hp-wmi.
 
+config LG_LAPTOP
+	tristate "LG Laptop Extras"
+	depends on ACPI
+	depends on ACPI_WMI
+	depends on INPUT
+	select INPUT_SPARSEKMAP
+	select LEDS_CLASS
+	help
+	 This driver adds support for hotkeys as well as control of keyboard
+	 backlight, battery maximum charge level and various other ACPI
+	 features.
+
+	 If you have an LG Gram laptop, say Y or M here.
+
 config MSI_LAPTOP
 	tristate "MSI Laptop Extras"
 	depends on ACPI

drivers/platform/x86/Makefile

@@ -9,6 +9,7 @@ obj-$(CONFIG_ASUS_NB_WMI)	+= asus-nb-wmi.o
 obj-$(CONFIG_ASUS_WIRELESS)	+= asus-wireless.o
 obj-$(CONFIG_EEEPC_LAPTOP)	+= eeepc-laptop.o
 obj-$(CONFIG_EEEPC_WMI)		+= eeepc-wmi.o
+obj-$(CONFIG_LG_LAPTOP)		+= lg-laptop.o
 obj-$(CONFIG_MSI_LAPTOP)	+= msi-laptop.o
 obj-$(CONFIG_ACPI_CMPC)		+= classmate-laptop.o
 obj-$(CONFIG_COMPAL_LAPTOP)	+= compal-laptop.o