HID: multitouch: Add support for GT7868Q

GT7868Q has incorrect data in the report and needs a fixup.
The change enables haptic touchpad on Lenovo ThinkBook 13x Gen 4
and has been tested on the device.
Signed-off-by: Dmitry Savin <envelsavinds@gmail.com>
Signed-off-by: Jiri Kosina <jkosina@suse.com>

drivers/hid/hid-ids.h

@@ -521,6 +521,8 @@
 #define USB_DEVICE_ID_GENERAL_TOUCH_WIN8_PIT_E100 0xe100
 
 #define I2C_VENDOR_ID_GOODIX		0x27c6
+#define I2C_DEVICE_ID_GOODIX_01E8	0x01e8
+#define I2C_DEVICE_ID_GOODIX_01E9	0x01e9
 #define I2C_DEVICE_ID_GOODIX_01F0	0x01f0
 
 #define USB_VENDOR_ID_GOODTOUCH		0x1aad

drivers/hid/hid-multitouch.c

@@ -1441,6 +1441,30 @@ static int mt_event(struct hid_device *hid, struct hid_field *field,
 	return 0;
 }
 
+static __u8 *mt_report_fixup(struct hid_device *hdev, __u8 *rdesc,
+			     unsigned int *size)
+{
+	if (hdev->vendor == I2C_VENDOR_ID_GOODIX &&
+	    (hdev->product == I2C_DEVICE_ID_GOODIX_01E8 ||
+	     hdev->product == I2C_DEVICE_ID_GOODIX_01E9)) {
+		if (rdesc[607] == 0x15) {
+			rdesc[607] = 0x25;
+			dev_info(
+				&hdev->dev,
+				"GT7868Q report descriptor fixup is applied.\n");
+		} else {
+			dev_info(
+				&hdev->dev,
+				"The byte is not expected for fixing the report descriptor. \
+It's possible that the touchpad firmware is not suitable for applying the fix. \
+got: %x\n",
+				rdesc[607]);
+		}
+	}
+
+	return rdesc;
+}
+
 static void mt_report(struct hid_device *hid, struct hid_report *report)
 {
 	struct mt_device *td = hid_get_drvdata(hid);
@@ -2035,6 +2059,14 @@ static const struct hid_device_id mt_devices[] = {
 		MT_BT_DEVICE(USB_VENDOR_ID_FRUCTEL,
 			USB_DEVICE_ID_GAMETEL_MT_MODE) },
 
+	/* Goodix GT7868Q devices */
+	{ .driver_data = MT_CLS_WIN_8_FORCE_MULTI_INPUT_NSMU,
+	  HID_DEVICE(BUS_I2C, HID_GROUP_ANY, I2C_VENDOR_ID_GOODIX,
+		     I2C_DEVICE_ID_GOODIX_01E8) },
+	{ .driver_data = MT_CLS_WIN_8_FORCE_MULTI_INPUT_NSMU,
+	  HID_DEVICE(BUS_I2C, HID_GROUP_ANY, I2C_VENDOR_ID_GOODIX,
+		     I2C_DEVICE_ID_GOODIX_01E8) },
+
 	/* GoodTouch panels */
 	{ .driver_data = MT_CLS_NSMU,
 		MT_USB_DEVICE(USB_VENDOR_ID_GOODTOUCH,
@@ -2270,6 +2302,7 @@ static struct hid_driver mt_driver = {
 	.feature_mapping = mt_feature_mapping,
 	.usage_table = mt_grabbed_usages,
 	.event = mt_event,
+	.report_fixup = mt_report_fixup,
 	.report = mt_report,
 	.suspend = pm_ptr(mt_suspend),
 	.reset_resume = pm_ptr(mt_reset_resume),