diff options
Diffstat (limited to 'drivers/hid/hid-core.c')
| -rw-r--r-- | drivers/hid/hid-core.c | 62 |
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, |