HID: Wiimote: Treat the d-pad as an analogue stick

The controllers from the Super Nintendo Classic Edition (AKA the SNES
Mini) appear as a Classic Controller Pro when connected to a Wii
Remote. All the buttons work as the same, with the d-pad being mapped
the same as the d-pad on the Classic Controller Pro. This differs from
the behaviour of most controllers with d-pads and no analogue sticks,
where the d-pad maps to ABS_HAT1X for left and right, and ABS_HAT1Y
for up and down. This patch adds an option to the hid-wiimote module
to make the Super Nintendo Classic Controller behave this way.

The patch has been tested with a Super Nintendo Classic Controller
plugged into a Wii Remote in both with the option both enabled and
disabled. When enabled the d-pad acts as the analogue control, and
when disabled it acts as it did before the patch was applied. This
patch has not been tested with e Wii Classic Controller (either the
original or the pro version) as I do not have one of these
controllers.

Although I have not tested it with these controllers, I think it is
likely this patch will also work with the NES Classic Edition
Controllers.

Signed-off-by: Daniel G. Morse <[e-mail]>
Reviewed-by: David Rheinsberg <[e-mail]>
Signed-off-by: Jiri Kosina <[e-mail]>

drivers/hid/hid-wiimote-core.c

···
 				USB_DEVICE_ID_NINTENDO_WIIMOTE2) },
 	{ }
 };
+
+bool wiimote_dpad_as_analog = false;
+module_param_named(dpad_as_analog, wiimote_dpad_as_analog, bool, 0644);
+MODULE_PARM_DESC(dpad_as_analog, "Use D-Pad as main analog input");
+
 MODULE_DEVICE_TABLE(hid, wiimote_hid_devices);
 
 static struct hid_driver wiimote_hid_driver = {

drivers/hid/hid-wiimote-modules.c

···
 	 * is the same as before.
 	 */
 
+	static const s8 digital_to_analog[3] = {0x20, 0, -0x20};
+
 	if (wdata->state.flags & WIIPROTO_FLAG_MP_ACTIVE) {
-		lx = ext[0] & 0x3e;
-		ly = ext[1] & 0x3e;
+		if (wiimote_dpad_as_analog) {
+			lx = digital_to_analog[1 - !(ext[4] & 0x80)
+				+ !(ext[1] & 0x01)];
+			ly = digital_to_analog[1 - !(ext[4] & 0x40)
+				+ !(ext[0] & 0x01)];
+		} else {
+			lx = (ext[0] & 0x3e) - 0x20;
+			ly = (ext[1] & 0x3e) - 0x20;
+		}
 	} else {
-		lx = ext[0] & 0x3f;
-		ly = ext[1] & 0x3f;
+		if (wiimote_dpad_as_analog) {
+			lx = digital_to_analog[1 - !(ext[4] & 0x80)
+				+ !(ext[5] & 0x02)];
+			ly = digital_to_analog[1 - !(ext[4] & 0x40)
+				+ !(ext[5] & 0x01)];
+		} else {
+			lx = (ext[0] & 0x3f) - 0x20;
+			ly = (ext[1] & 0x3f) - 0x20;
+		}
 	}
 
 	rx = (ext[0] >> 3) & 0x18;
···
 	rt <<= 1;
 	lt <<= 1;
 
-	input_report_abs(wdata->extension.input, ABS_HAT1X, lx - 0x20);
-	input_report_abs(wdata->extension.input, ABS_HAT1Y, ly - 0x20);
+	input_report_abs(wdata->extension.input, ABS_HAT1X, lx);
+	input_report_abs(wdata->extension.input, ABS_HAT1Y, ly);
 	input_report_abs(wdata->extension.input, ABS_HAT2X, rx - 0x20);
 	input_report_abs(wdata->extension.input, ABS_HAT2Y, ry - 0x20);
 	input_report_abs(wdata->extension.input, ABS_HAT3X, rt);
 	input_report_abs(wdata->extension.input, ABS_HAT3Y, lt);
 
-	input_report_key(wdata->extension.input,
-			 wiimod_classic_map[WIIMOD_CLASSIC_KEY_RIGHT],
-			 !(ext[4] & 0x80));
-	input_report_key(wdata->extension.input,
-			 wiimod_classic_map[WIIMOD_CLASSIC_KEY_DOWN],
-			 !(ext[4] & 0x40));
 	input_report_key(wdata->extension.input,
 			 wiimod_classic_map[WIIMOD_CLASSIC_KEY_LT],
 			 !(ext[4] & 0x20));
···
 			 wiimod_classic_map[WIIMOD_CLASSIC_KEY_ZR],
 			 !(ext[5] & 0x04));
 
-	if (wdata->state.flags & WIIPROTO_FLAG_MP_ACTIVE) {
+	if (!wiimote_dpad_as_analog) {
 		input_report_key(wdata->extension.input,
-			 wiimod_classic_map[WIIMOD_CLASSIC_KEY_LEFT],
-			 !(ext[1] & 0x01));
+				 wiimod_classic_map[WIIMOD_CLASSIC_KEY_RIGHT],
+				 !(ext[4] & 0x80));
 		input_report_key(wdata->extension.input,
-			 wiimod_classic_map[WIIMOD_CLASSIC_KEY_UP],
-			 !(ext[0] & 0x01));
-	} else {
-		input_report_key(wdata->extension.input,
-			 wiimod_classic_map[WIIMOD_CLASSIC_KEY_LEFT],
-			 !(ext[5] & 0x02));
-		input_report_key(wdata->extension.input,
-			 wiimod_classic_map[WIIMOD_CLASSIC_KEY_UP],
-			 !(ext[5] & 0x01));
+				 wiimod_classic_map[WIIMOD_CLASSIC_KEY_DOWN],
+				 !(ext[4] & 0x40));
+
+		if (wdata->state.flags & WIIPROTO_FLAG_MP_ACTIVE) {
+			input_report_key(wdata->extension.input,
+				 wiimod_classic_map[WIIMOD_CLASSIC_KEY_LEFT],
+				 !(ext[1] & 0x01));
+			input_report_key(wdata->extension.input,
+				 wiimod_classic_map[WIIMOD_CLASSIC_KEY_UP],
+				 !(ext[0] & 0x01));
+		} else {
+			input_report_key(wdata->extension.input,
+				 wiimod_classic_map[WIIMOD_CLASSIC_KEY_LEFT],
+				 !(ext[5] & 0x02));
+			input_report_key(wdata->extension.input,
+				 wiimod_classic_map[WIIMOD_CLASSIC_KEY_UP],
+				 !(ext[5] & 0x01));
+		}
 	}
 
 	input_sync(wdata->extension.input);

drivers/hid/hid-wiimote.h

···
 	struct work_struct init_worker;
 };
 
+extern bool wiimote_dpad_as_analog;
+
 /* wiimote modules */
 
 enum wiimod_module {