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path: root/drivers/hid/hid-core.c
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Diffstat (limited to 'drivers/hid/hid-core.c')
-rw-r--r--drivers/hid/hid-core.c62
1 files changed, 62 insertions, 0 deletions
diff --git a/drivers/hid/hid-core.c b/drivers/hid/hid-core.c
index cfcb69eb17d6..f932cd533d49 100644
--- a/drivers/hid/hid-core.c
+++ b/drivers/hid/hid-core.c
@@ -658,6 +658,58 @@ 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)
+{
+}
+
+/*
+ * Scan a report descriptor before the device is added to the bus.
+ * Sets device groups and other properties that determine what driver
+ * to load.
+ */
+static int hid_scan_report(struct hid_device *hid)
+{
+ unsigned int page = 0, delim = 0;
+ __u8 *start = hid->dev_rdesc;
+ __u8 *end = start + hid->dev_rsize;
+ unsigned int u, u_min = 0, u_max = 0;
+ struct hid_item item;
+
+ 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;
+ }
+ }
+ }
+
+ return 0;
+}
+
/**
* hid_parse_report - parse device report
*
@@ -2171,6 +2223,16 @@ int hid_add_device(struct hid_device *hdev)
if (!hdev->dev_rdesc)
return -ENODEV;
+ /*
+ * Scan generic devices for group information
+ */
+ if (hid_ignore_special_drivers ||
+ !hid_match_id(hdev, hid_have_special_driver)) {
+ ret = hid_scan_report(hdev);
+ if (ret)
+ hid_warn(hdev, "bad device descriptor (%d)\n", ret);
+ }
+
/* XXX hack, any other cleaner solution after the driver core
* is converted to allow more than 20 bytes as the device name? */
dev_set_name(&hdev->dev, "%04X:%04X:%04X.%04X", hdev->bus,