From 3dc8fc083dbfeede7b63a0c07581192e97711365 Mon Sep 17 00:00:00 2001 From: Benjamin Tissoires Date: Thu, 22 Aug 2013 14:51:07 +0200 Subject: [PATCH] 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: Benjamin Tissoires Reviewed-by: Henrik Rydberg Tested-by: Srinivas Pandruvada Signed-off-by: Jiri Kosina --- drivers/hid/hid-core.c | 102 ++++++++++++++++++++++++++--------------- 1 file changed, 64 insertions(+), 38 deletions(-) diff --git a/drivers/hid/hid-core.c b/drivers/hid/hid-core.c index e39dac68063c..ddd95f3e33c0 100644 --- a/drivers/hid/hid-core.c +++ b/drivers/hid/hid-core.c @@ -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; }