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>

2 files changed, 116 insertions, 0 deletions

diff --git a/Documentation/ABI/testing/sysfs-platform-lg-laptop b/Documentation/ABI/testing/sysfs-platform-lg-laptop
new file mode 100644
index 000000000000..cf47749b19df
--- /dev/null
+++ b/Documentation/ABI/testing/sysfs-platform-lg-laptop
@@ -0,0 +1,35 @@
+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.
diff --git a/Documentation/laptops/lg-laptop.rst b/Documentation/laptops/lg-laptop.rst
new file mode 100644
index 000000000000..e486fe7ddc35
--- /dev/null
+++ b/Documentation/laptops/lg-laptop.rst
@@ -0,0 +1,81 @@
+.. 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.