/* Register/unregister function support of a USB device function. 
Must be invoked when USB device is stopped.  */
void usbdc_register_function(struct usbdf_driver *func)
/* Register/unregister function support of a USB device function. 
Must be invoked when USB device is stopped.  */
void usbdc_register_function(struct usbdf_driver *func)
{
	list_insert_at_end(&usbdc.func_list, func);
}