hwmon: (oxp-sensors) Add tt_toggle attribute on supported boards

OneXPlayer boards from the last generation (both for OneXPlayer and AOK
ZOE brands) have a toggle in the EC to switch the "Turbo/Silent" button
into a different keyboard event.

Add a means to use that "Turbo button takeover" function and expose it
to userspace in a custom sysfs `tt_toggle` attribute. It can be read to
take the current state. Write 1|0 to activate the function. The specific
keycode is dependent on the board but can be checked by running
`evtest` utility.

Newer BIOS on the OneXPlayer added this function aside from string changes.
Add a board enum to differentiate it from the old OneXplayer Mini AMD BIOS.

Currently known supported boards:
- AOK ZOE A1
- OneXPlayer Mini AMD (only newer BIOS version supported)
- OneXPlayer Mini Pro

Signed-off-by: Joaquín Ignacio Aramendía <samsagax@gmail.com>
Link: https://lore.kernel.org/r/20230611143332.40590-2-samsagax@gmail.com
Signed-off-by: Guenter Roeck <linux@roeck-us.net>

1 files changed, 17 insertions, 0 deletions

diff --git a/Documentation/hwmon/oxp-sensors.rst b/Documentation/hwmon/oxp-sensors.rst
index 4ab442301415..0ca1f7728c34 100644
--- a/Documentation/hwmon/oxp-sensors.rst
+++ b/Documentation/hwmon/oxp-sensors.rst
@@ -19,6 +19,11 @@ out the EC registers and values to write to since the EC layout and model is
 different. Aya Neo devices preceding the AIR may not be supportable as the EC
 model is different and do not appear to have manual control capabilities.
 
+Some models have a toggle for changing the behaviour of the "Turbo/Silent"
+button of the device. It will change the key event that it triggers with
+a flip of the `tt_toggle` attribute. See below for boards that support this
+function.
+
 Supported devices
 -----------------
 
@@ -33,6 +38,11 @@ Currently the driver supports the following handhelds:
  - OneXPlayer mini AMD
  - OneXPlayer mini AMD PRO
 
+"Turbo/Silent" button behaviour toggle is only supported on:
+ - AOK ZOE A1
+ - OneXPlayer mini AMD (only with updated alpha BIOS)
+ - OneXPlayer mini AMD PRO
+
 Sysfs entries
 -------------
 
@@ -49,3 +59,10 @@ pwm1
   Read Write. Read this attribute to see current duty cycle in the range [0-255].
   When pwm1_enable is set to "1" (manual) write any value in the range [0-255]
   to set fan speed.
+
+tt_toggle
+  Read Write. Read this attribute to check the status of the turbo/silent
+  button behaviour function. Write "1" to activate the switch and "0" to
+  deactivate it. The specific keycodes and behaviour is specific to the device
+  both with this function on and off. This attribute is attached to the platform
+  driver and not to the hwmon driver (/sys/devices/platform/oxp-platform/tt_toggle)