TELEM_MAX_DEV
minor = ida_alloc_max(&telem_ida, TELEM_MAX_DEV-1, GFP_KERNEL);
ret = alloc_chrdev_region(&dev_num, 0, TELEM_MAX_DEV, TELEM_DEV_NAME);
unregister_chrdev_region(MKDEV(telem_major, 0), TELEM_MAX_DEV);
unregister_chrdev_region(MKDEV(telem_major, 0), TELEM_MAX_DEV);