[PATCH v3 4/9] HID: multitouch: support getting the tip state from HID_DG_TOUCH fields

[Aditya Garg <gargaditya08@live.com>]

From: Kerem Karabay <kekrby@gmail.com>

This is necessary on Apple Touch Bars, where 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 c2ef8f21ea8f
("HID: multitouch: add support for trackpads").

Signed-off-by: Kerem Karabay <kekrby@gmail.com>
Signed-off-by: Aditya Garg <gargaditya08@live.com>
---
 drivers/hid/hid-multitouch.c | 14 ++++++++++----
 1 file changed, 10 insertions(+), 4 deletions(-)

diff --git a/drivers/hid/hid-multitouch.c b/drivers/hid/hid-multitouch.c
index 3e92789ed..571435da5 100644
--- a/drivers/hid/hid-multitouch.c
+++ b/drivers/hid/hid-multitouch.c
@@ -72,6 +72,7 @@ MODULE_LICENSE("GPL");
 #define MT_QUIRK_FORCE_MULTI_INPUT	BIT(20)
 #define MT_QUIRK_DISABLE_WAKEUP		BIT(21)
 #define MT_QUIRK_ORIENTATION_INVERT	BIT(22)
+#define MT_QUIRK_TOUCH_IS_TIPSTATE	BIT(23)
 
 #define MT_INPUTMODE_TOUCHSCREEN	0x02
 #define MT_INPUTMODE_TOUCHPAD		0x03
@@ -809,6 +810,15 @@ 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.
+			 * Let's just ignore this field unless the quirk is set.
+			 */
+			if (!(cls->quirks & MT_QUIRK_TOUCH_IS_TIPSTATE))
+				return -1;
+
+			fallthrough;
 		case HID_DG_TIPSWITCH:
 			if (field->application != HID_GD_SYSTEM_MULTIAXIS)
 				input_set_capability(hi->input,
@@ -872,10 +882,6 @@ 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;
-- 
2.43.0