Man page 9 : register_chrdev_region

register_chrdev_region - register a range of device numbers

int register_chrdev_region(dev_t  from , unsigned  count , const char *  name );

from
    the first in the desired range of device numbers; must include the major number.

count
    the number of consecutive device numbers required

name
    the name of the device or driver.

Return value is zero on success, a negative error code on failure.