HID: hid-multitouch: Switch to device groups

Switch the driver over to device group handling.  By adding the
HID_GROUP_MULTITOUCH group to hid-core, hid-generic will no longer
match multitouch devices.  By adding the HID_GROUP_MULTITOUCH entry to
the device list, hid-multitouch will match all unknown multitouch
devices, and udev will automatically load the module.

Since HID_QUIRK_MULTITOUCH never gets set, the special quirks handling
can be removed.  Since all HID MT devices have HID_DG_CONTACTID, they
can be removed from the hid_have_special_driver list.

With this patch, the unknown device ids are no longer NULL, so the code
is modified to check for the generic entry instead.
Signed-off-by: Henrik Rydberg <rydberg@euromail.se>
Acked-by: Benjamin Tissoires <benjamin.tissoires@gmail.com>
Signed-off-by: Jiri Kosina <jkosina@suse.cz>

drivers/hid/hid-input.c

@@ -638,10 +638,6 @@ 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;
@@ -1208,13 +1204,6 @@ 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;
 

drivers/hid/hid-multitouch.c

@@ -635,6 +635,21 @@ static void mt_set_maxcontacts(struct hid_device *hdev)
 	}
 }
 
+static void mt_post_parse_default_settings(struct mt_device *td)
+{
+	__s32 quirks = td->mtclass.quirks;
+
+	/* unknown serial device needs special quirks */
+	if (td->touches_by_report == 1) {
+		quirks |= MT_QUIRK_ALWAYS_VALID;
+		quirks &= ~MT_QUIRK_NOT_SEEN_MEANS_UP;
+		quirks &= ~MT_QUIRK_VALID_IS_INRANGE;
+		quirks &= ~MT_QUIRK_VALID_IS_CONFIDENCE;
+	}
+
+	td->mtclass.quirks = quirks;
+}
+
 static int mt_probe(struct hid_device *hdev, const struct hid_device_id *id)
 {
 	int ret, i;
@@ -654,7 +669,6 @@ static int mt_probe(struct hid_device *hdev, const struct hid_device_id *id)
 	 * that emit events over several HID messages.
 	 */
 	hdev->quirks |= HID_QUIRK_NO_INPUT_SYNC;
-	hdev->quirks &= ~HID_QUIRK_MULTITOUCH;
 
 	td = kzalloc(sizeof(struct mt_device), GFP_KERNEL);
 	if (!td) {
@@ -674,14 +688,8 @@ static int mt_probe(struct hid_device *hdev, const struct hid_device_id *id)
 	if (ret)
 		goto fail;
 
-	if (!id && td->touches_by_report == 1) {
-		/* the device has been sent by hid-generic */
-		mtclass = &td->mtclass;
-		mtclass->quirks |= MT_QUIRK_ALWAYS_VALID;
-		mtclass->quirks &= ~MT_QUIRK_NOT_SEEN_MEANS_UP;
-		mtclass->quirks &= ~MT_QUIRK_VALID_IS_INRANGE;
-		mtclass->quirks &= ~MT_QUIRK_VALID_IS_CONFIDENCE;
-	}
+	if (id->vendor == HID_ANY_ID && id->product == HID_ANY_ID)
+		mt_post_parse_default_settings(td);
 
 	td->slots = kzalloc(td->maxcontacts * sizeof(struct mt_slot),
 				GFP_KERNEL);
@@ -999,6 +1007,8 @@ static const struct hid_device_id mt_devices[] = {
 		HID_USB_DEVICE(USB_VENDOR_ID_XIROKU,
 			USB_DEVICE_ID_XIROKU_CSR2) },
 
+	/* Generic MT device */
+	{ HID_DEVICE(HID_BUS_ANY, HID_GROUP_MULTITOUCH, HID_ANY_ID, HID_ANY_ID) },
 	{ }
 };
 MODULE_DEVICE_TABLE(hid, mt_devices);

include/linux/hid.h

@@ -317,7 +317,6 @@ 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
@@ -328,6 +327,7 @@ struct hid_item {
  * HID device groups
  */
 #define HID_GROUP_GENERIC			0x0001
+#define HID_GROUP_MULTITOUCH			0x0002
 
 /*
  * This is the global environment of the parser. This information is