USB_DEVICE_DEV
retval = register_chrdev_region(USB_DEVICE_DEV, USB_DEVICE_MAX,
retval = cdev_add(&usb_device_cdev, USB_DEVICE_DEV, USB_DEVICE_MAX);
unregister_chrdev_region(USB_DEVICE_DEV, USB_DEVICE_MAX);
unregister_chrdev_region(USB_DEVICE_DEV, USB_DEVICE_MAX);