HID: add autodetection of multitouch devices

As mentioned by http://www.microsoft.com/whdc/device/input/DigitizerDrvs_touch.mspx
multitouch devices are those that have the input report HID_CONTACTID.

This patch detects this and unloads the generic-usb driver.

Signed-off-by: Benjamin Tissoires <benjamin.tissoires@enac.fr>
Signed-off-by: Jiri Kosina <jkosina@suse.cz>

drivers/hid/hid-core.c

@@ -1212,6 +1212,12 @@ int hid_connect(struct hid_device *hdev, unsigned int connect_mask)
 	if ((connect_mask & HID_CONNECT_HIDINPUT) && !hidinput_connect(hdev,
 				connect_mask & HID_CONNECT_HIDINPUT_FORCE))
 		hdev->claimed |= HID_CLAIMED_INPUT;
+	if (hdev->quirks & HID_QUIRK_MULTITOUCH) {
+		/* this device should be handled by hid-multitouch, skip it */
+		hdev->quirks &= ~HID_QUIRK_MULTITOUCH;
+		return -ENODEV;
+	}
+
 	if ((connect_mask & HID_CONNECT_HIDDEV) && hdev->hiddev_connect &&
 			!hdev->hiddev_connect(hdev,
 				connect_mask & HID_CONNECT_HIDDEV_FORCE))

drivers/hid/hid-input.c

@@ -474,6 +474,10 @@ static void hidinput_configure_usage(struct hid_input *hidinput, struct hid_fiel
 			map_key_clear(BTN_STYLUS2);
 			break;
 
+		case 0x51: /* ContactID */
+			device->quirks |= HID_QUIRK_MULTITOUCH;
+			goto unknown;
+
 		default:  goto unknown;
 		}
 		break;
@@ -978,6 +982,13 @@ int hidinput_connect(struct hid_device *hid, unsigned int force)
 		}
 	}
 
+	if (hid->quirks & HID_QUIRK_MULTITOUCH) {
+		/* generic hid does not know how to handle multitouch devices */
+		if (hidinput)
+			goto out_cleanup;
+		goto out_unwind;
+	}
+
 	if (hidinput && input_register_device(hidinput->input))
 		goto out_cleanup;
 

include/linux/hid.h

@@ -312,6 +312,7 @@ struct hid_item {
 #define HID_QUIRK_BADPAD			0x00000020
 #define HID_QUIRK_MULTI_INPUT			0x00000040
 #define HID_QUIRK_HIDINPUT_FORCE		0x00000080
+#define HID_QUIRK_MULTITOUCH			0x00000100
 #define HID_QUIRK_SKIP_OUTPUT_REPORTS		0x00010000
 #define HID_QUIRK_FULLSPEED_INTERVAL		0x10000000
 #define HID_QUIRK_NO_INIT_REPORTS		0x20000000