HID: add dynids facility

Allow adding new devices to the hid drivers on the fly without
a need of kernel recompilation.

Now, one can test a driver e.g. by:
echo 0003:045E:00F0.0003 > ../generic-usb/unbind
echo 0003 045E 00F0 > new_id
from some driver subdir.

Signed-off-by: Jiri Slaby <jirislaby@gmail.com>
Signed-off-by: Jiri Kosina <jkosina@suse.cz>
diff --git a/include/linux/hid.h b/include/linux/hid.h
index 2c20f20..215035b 100644
--- a/include/linux/hid.h
+++ b/include/linux/hid.h
@@ -531,6 +531,8 @@
  * @name: driver name (e.g. "Footech_bar-wheel")
  * @id_table: which devices is this driver for (must be non-NULL for probe
  * 	      to be called)
+ * @dyn_list: list of dynamically added device ids
+ * @dyn_lock: lock protecting @dyn_list
  * @probe: new device inserted
  * @remove: device removed (NULL if not a hot-plug capable driver)
  * @report_table: on which reports to call raw_event (NULL means all)
@@ -558,6 +560,9 @@
 	char *name;
 	const struct hid_device_id *id_table;
 
+	struct list_head dyn_list;
+	spinlock_t dyn_lock;
+
 	int (*probe)(struct hid_device *dev, const struct hid_device_id *id);
 	void (*remove)(struct hid_device *dev);