xpadneo, core: Add configuration for disabling Xbox logo shift-mode

For use with Steam, the `Guide`+`A` is mapped to the QAM. To not lose
the profile switching behavior, let the user configure this.

Co-authored-by: Kai Krakow <kai@kaishome.de>
Fixes: #419
Closes: #435
Signed-off-by: Kai Krakow <kai@kaishome.de>

Author: BoukeHaarsma23

docs/CONFIGURATION.md

@@ -33,6 +33,10 @@ files in `/sys/module/hid_xpadneo/parameters`:
     * `16` if your controller boots in Linux mode (auto-detected, do not change manually)
     * `32` if you prefer to use Nintendo button mappings (i.e., 8BitDo controllers, defaults to off)
     * `64` if your controller has a awkwardly mapped Share button (auto-detected, do not set manually)
+* 'disable_shift_mode' (default 0)
+  * Let's you disable Xbox logo button shift behavior
+  * '0' Xbox logo button will be used as shift
+  * '1' will pass through the Xbox logo button as is
 
 Some settings may need to be changed at loading time of the module, take a look at the following example to see how
 that works:

docs/README.md

@@ -217,6 +217,9 @@ or Y while holding down the Xbox logo button. However, the following caveats app
 - Full support will be available once the Xbox Elite Series 2 controller is fully supported.
 - If you hold the button for too long, the controller will turn off - we cannot prevent that.
 
+**Important:** Emulated profile switching won't work if you disabled the shift-mode of the Xbox logo button (module
+parameter `disable_shift_mode`).
+
 
 ## Getting Started
 

hid-xpadneo/src/hid-xpadneo.c

@@ -52,6 +52,12 @@ MODULE_PARM_DESC(enable_rolling_axis,
 		 "(bool) Enable rolling axis by combining both triggers, out of spec for many games. (deprecated) "
 		 "0: disable, 1: enable.");
 
+static bool param_disable_shift_mode = 0;
+module_param_named(disable_shift_mode, param_disable_shift_mode, bool, 0644);
+MODULE_PARM_DESC(disable_shift_mode,
+		 "(bool) Disable use Xbox logo button as shift. Will prohibit profile switching when enabled. "
+		 "0: disable, 1: enable.");
+
 static struct {
 	char *args[17];
 	unsigned int nargs;
@@ -947,7 +953,8 @@ static int xpadneo_event(struct hid_device *hdev, struct hid_field *field,
 			xdata->last_abs_rz = value;
 			goto combine_z_axes;
 		}
-	} else if ((usage->type == EV_KEY) && (usage->code == BTN_XBOX)) {
+	} else if (!param_disable_shift_mode && (usage->type == EV_KEY)
+		   && (usage->code == BTN_XBOX)) {
 		/*
 		 * Handle the Xbox logo button: We want to cache the button
 		 * down event to allow for profile switching. The button will