Input: add ABS_PROFILE to uapi and documentation

Define new ABS_PROFILE axis for input devices which need it, e.g. X-Box
Adaptive Controller and X-Box Elite 2.

Signed-off-by: Nate Yocom <nate@yocom.org>
Link: https://lore.kernel.org/r/20220908173930.28940-4-nate@yocom.org
Signed-off-by: Dmitry Torokhov <dmitry.torokhov@gmail.com>

Author: nate-yocom

Documentation/input/event-codes.rst

@@ -235,6 +235,12 @@ A few EV_ABS codes have special meanings:
     BTN_TOOL_<name> signals the type of tool that is currently detected by the
     hardware and is otherwise independent of ABS_DISTANCE and/or BTN_TOUCH.
 
+* ABS_PROFILE:
+
+  - Used to describe the state of a multi-value profile switch.  An event is
+    emitted only when the selected profile changes, indicating the newly
+    selected profile value.
+
 * ABS_MT_<name>:
 
   - Used to describe multitouch input events. Please see

Documentation/input/gamepad.rst

@@ -189,3 +189,9 @@ Gamepads report the following events:
 - Rumble:
 
   Rumble is advertised as FF_RUMBLE.
+
+- Profile:
+
+  Some pads provide a multi-value profile selection switch.  An example is the
+  XBox Adaptive and the XBox Elite 2 controllers.  When the active profile is
+  switched, its newly selected value is emitted as an ABS_PROFILE event.

drivers/hid/hid-debug.c

@@ -1014,7 +1014,8 @@ static const char *absolutes[ABS_CNT] = {
 	[ABS_HAT3Y] = "Hat 3Y",		[ABS_PRESSURE] = "Pressure",
 	[ABS_DISTANCE] = "Distance",	[ABS_TILT_X] = "XTilt",
 	[ABS_TILT_Y] = "YTilt",		[ABS_TOOL_WIDTH] = "ToolWidth",
-	[ABS_VOLUME] = "Volume",	[ABS_MISC] = "Misc",
+	[ABS_VOLUME] = "Volume",	[ABS_PROFILE] = "Profile",
+	[ABS_MISC] = "Misc",
 	[ABS_MT_TOUCH_MAJOR] = "MTMajor",
 	[ABS_MT_TOUCH_MINOR] = "MTMinor",
 	[ABS_MT_WIDTH_MAJOR] = "MTMajorW",

include/uapi/linux/input-event-codes.h

@@ -862,6 +862,7 @@
 #define ABS_TOOL_WIDTH		0x1c
 
 #define ABS_VOLUME		0x20
+#define ABS_PROFILE		0x21
 
 #define ABS_MISC		0x28