#include <linux/types.h>
#include <linux/kdev_t.h>
Hoje: 12 bits major, 20 bits minor

MAJOR(dev_t)
MINOR(dev_t)
MKDEV(major, minor)
register_chrdev_region(dev_t f, unsigned int n, char *name);
alloc_chrdev_region(dev_t *d, unsigned int fm, unsigned int n, char *name);
unregister_chrdev_region(dev_t f, int n);