PMSG_NAME
#define pr_fmt(fmt) PMSG_NAME ": " fmt
pmsg_major = register_chrdev(0, PMSG_NAME, &pmsg_fops);
pmsg_class = class_create(PMSG_NAME);
NULL, "%s%d", PMSG_NAME, 0);
unregister_chrdev(pmsg_major, PMSG_NAME);
unregister_chrdev(pmsg_major, PMSG_NAME);