WWAN_MAX_MINORS
wwan_major = __register_chrdev(0, 0, WWAN_MAX_MINORS, "wwan_port",
__unregister_chrdev(wwan_major, 0, WWAN_MAX_MINORS, "wwan_port");
minor = ida_alloc_range(&minors, 0, WWAN_MAX_MINORS - 1, GFP_KERNEL);