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 <benjamin.tissoires@xxxxxxxxxx>
---
changes in v3:
- remove one remnant duplicate message
- amended commit message
- re-add initializer of hid->group (set to HID_GROUP_GENERIC)
changes in v2:
- moved "flags" processing in patch 2/3 (so use hid->group in this patch)
- hid_scan_report() is less verbose when errors are found in the descriptor
- hid_scan_report() is tolerant to parsing errors
- fixed usage_page handling in hid_scan_collection(), which fixes sensors detection
- amended commit message
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 3efe19f..9fc1220 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;
}
--
1.8.3.1
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