Commit 3dc8fc08 authored by Benjamin Tissoires's avatar Benjamin Tissoires Committed by Jiri Kosina
Browse files

HID: Use hid_parser for pre-scanning the report descriptors 



The Win 8 detection is sufficiently complex to warrant use of the full
parser code, in spite of the inferred memory usage. Therefore, we can use
the existing HID parser in hid-core for hid_scan_report() by re-using the
code from hid_open_report(). hid_parser_global, hid_parser_local and
hid_parser_reserved does not have any side effects. We just need to
reimplement the MAIN_ITEM callback to have a proper parsing without side
effects.

Signed-off-by: default avatarBenjamin Tissoires <benjamin.tissoires@redhat.com>
Reviewed-by: default avatarHenrik Rydberg <rydberg@euromail.se>
Tested-by: default avatarSrinivas <Pandruvada&lt;srinivas.pandruvada@linux.intel.com>
Signed-off-by: default avatarJiri Kosina <jkosina@suse.cz>
parent c08d46aa

drivers/hid/hid-core.c

+64 −38
Original line number Diff line number Diff line
@@ -677,12 +677,52 @@ static u8 *fetch_item(__u8 *start, __u8 *end, struct hid_item *item) 
	return NULL;

}



static void hid_scan_usage(struct hid_device *hid, u32 usage)

static void hid_scan_input_usage(struct hid_parser *parser, u32 usage)

{

	struct hid_device *hid = parser->device;



	if (usage == HID_DG_CONTACTID)

		hid->group = HID_GROUP_MULTITOUCH;

}



static void hid_scan_collection(struct hid_parser *parser, unsigned type)

{

	struct hid_device *hid = parser->device;



	if (((parser->global.usage_page << 16) == HID_UP_SENSOR) &&

	    type == HID_COLLECTION_PHYSICAL)

		hid->group = HID_GROUP_SENSOR_HUB;

}



static int hid_scan_main(struct hid_parser *parser, struct hid_item *item)

{

	__u32 data;

	int i;



	data = item_udata(item);



	switch (item->tag) {

	case HID_MAIN_ITEM_TAG_BEGIN_COLLECTION:

		hid_scan_collection(parser, data & 0xff);

		break;

	case HID_MAIN_ITEM_TAG_END_COLLECTION:

		break;

	case HID_MAIN_ITEM_TAG_INPUT:

		for (i = 0; i < parser->local.usage_index; i++)

			hid_scan_input_usage(parser, parser->local.usage[i]);

		break;

	case HID_MAIN_ITEM_TAG_OUTPUT:

		break;

	case HID_MAIN_ITEM_TAG_FEATURE:

		break;

	}



	/* Reset the local parser environment */

	memset(&parser->local, 0, sizeof(parser->local));



	return 0;

}



/*

 * Scan a report descriptor before the device is added to the bus.

 * Sets device groups and other properties that determine what driver
@@ -690,48 +730,34 @@ static void hid_scan_usage(struct hid_device *hid, u32 usage) 
 */

static int hid_scan_report(struct hid_device *hid)

{

	unsigned int page = 0, delim = 0;

	struct hid_parser *parser;

	struct hid_item item;

	__u8 *start = hid->dev_rdesc;

	__u8 *end = start + hid->dev_rsize;

	unsigned int u, u_min = 0, u_max = 0;

	struct hid_item item;

	static int (*dispatch_type[])(struct hid_parser *parser,

				      struct hid_item *item) = {

		hid_scan_main,

		hid_parser_global,

		hid_parser_local,

		hid_parser_reserved

	};



	parser = vzalloc(sizeof(struct hid_parser));

	if (!parser)

		return -ENOMEM;



	parser->device = hid;

	hid->group = HID_GROUP_GENERIC;

	while ((start = fetch_item(start, end, &item)) != NULL) {

		if (item.format != HID_ITEM_FORMAT_SHORT)

			return -EINVAL;

		if (item.type == HID_ITEM_TYPE_GLOBAL) {

			if (item.tag == HID_GLOBAL_ITEM_TAG_USAGE_PAGE)

				page = item_udata(&item) << 16;

		} else if (item.type == HID_ITEM_TYPE_LOCAL) {

			if (delim > 1)

				break;

			u = item_udata(&item);

			if (item.size <= 2)

				u += page;

			switch (item.tag) {

			case HID_LOCAL_ITEM_TAG_DELIMITER:

				delim += !!u;

				break;

			case HID_LOCAL_ITEM_TAG_USAGE:

				hid_scan_usage(hid, u);

				break;

			case HID_LOCAL_ITEM_TAG_USAGE_MINIMUM:

				u_min = u;

				break;

			case HID_LOCAL_ITEM_TAG_USAGE_MAXIMUM:

				u_max = u;

				for (u = u_min; u <= u_max; u++)

					hid_scan_usage(hid, u);

				break;

			}

		} else if (page == HID_UP_SENSOR &&

			item.type == HID_ITEM_TYPE_MAIN &&

			item.tag == HID_MAIN_ITEM_TAG_BEGIN_COLLECTION &&

			(item_udata(&item) & 0xff) == HID_COLLECTION_PHYSICAL)

			hid->group = HID_GROUP_SENSOR_HUB;

	}



	/*

	 * The parsing is simpler than the one in hid_open_report() as we should

	 * be robust against hid errors. Those errors will be raised by

	 * hid_open_report() anyway.

	 */

	while ((start = fetch_item(start, end, &item)) != NULL)

		dispatch_type[item.type](parser, &item);



	vfree(parser);

	return 0;

}

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