HID: detect Win 8 multitouch devices in core

Detecting Win 8 multitouch devices in core allows us to set quirks
before the device is parsed through hid_hw_start().
It also simplifies the detection of those devices in hid-multitouch and
makes the handling of those devices cleaner.

As Win 8 multitouch panels are in the group multitouch and rely on a
special feature to be detected, this patch adds a bitfield in the parser.
Signed-off-by: Benjamin Tissoires <benjamin.tissoires@redhat.com>
Reviewed-by: Henrik Rydberg <rydberg@euromail.se>
Tested-by: Srinivas Pandruvada<srinivas.pandruvada@linux.intel.com>
Signed-off-by: Jiri Kosina <jkosina@suse.cz>

drivers/hid/hid-core.c

@@ -685,6 +685,13 @@ static void hid_scan_input_usage(struct hid_parser *parser, u32 usage)
 		hid->group = HID_GROUP_MULTITOUCH;
 }
 
+static void hid_scan_feature_usage(struct hid_parser *parser, u32 usage)
+{
+	if (usage == 0xff0000c5 && parser->global.report_count == 256 &&
+	    parser->global.report_size == 8)
+		parser->scan_flags |= HID_SCAN_FLAG_MT_WIN_8;
+}
+
 static void hid_scan_collection(struct hid_parser *parser, unsigned type)
 {
 	struct hid_device *hid = parser->device;
@@ -714,6 +721,8 @@ static int hid_scan_main(struct hid_parser *parser, struct hid_item *item)
 	case HID_MAIN_ITEM_TAG_OUTPUT:
 		break;
 	case HID_MAIN_ITEM_TAG_FEATURE:
+		for (i = 0; i < parser->local.usage_index; i++)
+			hid_scan_feature_usage(parser, parser->local.usage[i]);
 		break;
 	}
 
@@ -757,6 +766,13 @@ static int hid_scan_report(struct hid_device *hid)
 	while ((start = fetch_item(start, end, &item)) != NULL)
 		dispatch_type[item.type](parser, &item);
 
+	/*
+	 * Handle special flags set during scanning.
+	 */
+	if ((parser->scan_flags & HID_SCAN_FLAG_MT_WIN_8) &&
+	    (hid->group == HID_GROUP_MULTITOUCH))
+		hid->group = HID_GROUP_MULTITOUCH_WIN_8;
+
 	vfree(parser);
 	return 0;
 }

drivers/hid/hid-multitouch.c

@@ -133,6 +133,7 @@ static void mt_post_parse(struct mt_device *td);
 #define MT_CLS_NSMU				0x000a
 #define MT_CLS_DUAL_CONTACT_NUMBER		0x0010
 #define MT_CLS_DUAL_CONTACT_ID			0x0011
+#define MT_CLS_WIN_8				0x0012
 
 /* vendor specific classes */
 #define MT_CLS_3M				0x0101
@@ -205,6 +206,11 @@ static struct mt_class mt_classes[] = {
 			MT_QUIRK_CONTACT_CNT_ACCURATE |
 			MT_QUIRK_SLOT_IS_CONTACTID,
 		.maxcontacts = 2 },
+	{ .name = MT_CLS_WIN_8,
+		.quirks = MT_QUIRK_ALWAYS_VALID |
+			MT_QUIRK_IGNORE_DUPLICATES |
+			MT_QUIRK_HOVERING |
+			MT_QUIRK_CONTACT_CNT_ACCURATE },
 
 	/*
 	 * vendor specific classes
@@ -332,19 +338,6 @@ static void mt_feature_mapping(struct hid_device *hdev,
 			td->maxcontacts = td->mtclass.maxcontacts;
 
 		break;
-	case 0xff0000c5:
-		if (field->report_count == 256 && field->report_size == 8) {
-			/* Win 8 devices need special quirks */
-			__s32 *quirks = &td->mtclass.quirks;
-			*quirks |= MT_QUIRK_ALWAYS_VALID;
-			*quirks |= MT_QUIRK_IGNORE_DUPLICATES;
-			*quirks |= MT_QUIRK_HOVERING;
-			*quirks |= MT_QUIRK_CONTACT_CNT_ACCURATE;
-			*quirks &= ~MT_QUIRK_NOT_SEEN_MEANS_UP;
-			*quirks &= ~MT_QUIRK_VALID_IS_INRANGE;
-			*quirks &= ~MT_QUIRK_VALID_IS_CONFIDENCE;
-		}
-		break;
 	}
 }
 
@@ -1346,6 +1339,11 @@ static const struct hid_device_id mt_devices[] = {
 
 	/* Generic MT device */
 	{ HID_DEVICE(HID_BUS_ANY, HID_GROUP_MULTITOUCH, HID_ANY_ID, HID_ANY_ID) },
+
+	/* Generic Win 8 certified MT device */
+	{  .driver_data = MT_CLS_WIN_8,
+		HID_DEVICE(HID_BUS_ANY, HID_GROUP_MULTITOUCH_WIN_8,
+			HID_ANY_ID, HID_ANY_ID) },
 	{ }
 };
 MODULE_DEVICE_TABLE(hid, mt_devices);

include/linux/hid.h

@@ -295,6 +295,7 @@ struct hid_item {
 #define HID_GROUP_GENERIC			0x0001
 #define HID_GROUP_MULTITOUCH			0x0002
 #define HID_GROUP_SENSOR_HUB			0x0003
+#define HID_GROUP_MULTITOUCH_WIN_8		0x0004
 
 /*
  * This is the global environment of the parser. This information is
@@ -532,6 +533,8 @@ static inline void hid_set_drvdata(struct hid_device *hdev, void *data)
 #define HID_GLOBAL_STACK_SIZE 4
 #define HID_COLLECTION_STACK_SIZE 4
 
+#define HID_SCAN_FLAG_MT_WIN_8			0x00000001
+
 struct hid_parser {
 	struct hid_global     global;
 	struct hid_global     global_stack[HID_GLOBAL_STACK_SIZE];
@@ -540,6 +543,7 @@ struct hid_parser {
 	unsigned              collection_stack[HID_COLLECTION_STACK_SIZE];
 	unsigned              collection_stack_ptr;
 	struct hid_device    *device;
+	unsigned              scan_flags;
 };
 
 struct hid_class_descriptor {