HID: multitouch: support getting the tip state from HID_DG_TOUCH fields in Apple Touch Bar

In Apple Touch Bar, the tip state is contained in fields with the
HID_DG_TOUCH usage. This feature is gated by a quirk in order to
prevent breaking other devices, see commit c2ef8f2
("HID: multitouch: add support for trackpads").

Acked-by: Benjamin Tissoires <[email protected]>
Signed-off-by: Kerem Karabay <[email protected]>
Co-developed-by: Aditya Garg <[email protected]>
Signed-off-by: Aditya Garg <[email protected]>
Signed-off-by: Jiri Kosina <[email protected]>

Author: kekrby

drivers/hid/hid-multitouch.c

@@ -827,6 +827,17 @@ static int mt_touch_input_mapping(struct hid_device *hdev, struct hid_input *hi,
 
 			MT_STORE_FIELD(confidence_state);
 			return 1;
+		case HID_DG_TOUCH:
+			/*
+			 * Legacy devices use TIPSWITCH and not TOUCH.
+			 * One special case here is of the Apple Touch Bars.
+			 * In these devices, the tip state is contained in
+			 * fields with the HID_DG_TOUCH usage.
+			 * Let's just ignore this field for other devices.
+			 */
+			if (!(cls->quirks & MT_QUIRK_APPLE_TOUCHBAR))
+				return -1;
+			fallthrough;
 		case HID_DG_TIPSWITCH:
 			if (field->application != HID_GD_SYSTEM_MULTIAXIS)
 				input_set_capability(hi->input,
@@ -897,10 +908,6 @@ static int mt_touch_input_mapping(struct hid_device *hdev, struct hid_input *hi,
 		case HID_DG_CONTACTMAX:
 			/* contact max are global to the report */
 			return -1;
-		case HID_DG_TOUCH:
-			/* Legacy devices use TIPSWITCH and not TOUCH.
-			 * Let's just ignore this field. */
-			return -1;
 		}
 		/* let hid-input decide for the others */
 		return 0;