__register_chrdev(9) [centos man page]

__REGISTER_CHRDEV(9)						   Char devices 					      __REGISTER_CHRDEV(9)

NAME

       __register_chrdev - create and register a cdev occupying a range of minors

SYNOPSIS

       int __register_chrdev(unsigned int major, unsigned int baseminor, unsigned int count, const char * name,
			     const struct file_operations * fops);

ARGUMENTS

       major
	   major device number or 0 for dynamic allocation

       baseminor
	   first of the requested range of minor numbers

       count
	   the number of minor numbers required

       name
	   name of this range of devices

       fops
	   file operations associated with this devices

DESCRIPTION

       If major == 0 this functions will dynamically allocate a major and return its number.

       If major > 0 this function will attempt to reserve a device with the given major number and will return zero on success.

       Returns a -ve errno on failure.

       The name of this device has nothing to do with the name of the device in /dev. It only helps to keep track of the different owners of
       devices. If your module name has only one type of devices it's ok to use e.g. the name of the module here.

COPYRIGHT

Kernel Hackers Manual 3.10					     June 2014						      __REGISTER_CHRDEV(9)

MAKEDEV(3)						   BSD Library Functions Manual 						MAKEDEV(3)

NAME

     makedev, major, minor -- device number conversion

SYNOPSIS

     #include <sys/types.h>

     dev_t
     makedev(int major, int minor);

     int
     major(dev_t dev);

     int
     minor(dev_t dev);

DESCRIPTION

     The makedev() macro allows a unique device number to be generated based on its major and minor number.  The major() and minor() macros can be
     used to obtain the original numbers from the device number dev.

     In previous implementations of FreeBSD all block and character devices were uniquely identified by a pair of major and minor numbers.  The
     major number referred to a certain device class (e.g. disks, TTYs) while the minor number identified an instance within the device class.
     Later versions of FreeBSD automatically generate a unique device number for each character device visible in /dev/.  These numbers are not
     divided in device classes.

     On FreeBSD these macros are only used by utilities that need to exchange numbers with other operating systems that may use different encod-
     ings for dev_t, but also applications that present these numbers to the user in a more conventional way.

RETURN VALUES

     The major() macro returns a device major number that has a value between 0 and 255.  The minor() macro returns a device minor number whose
     value can span the complete range of an int.

SEE ALSO

     mknod(2), devname(3), devfs(5)

BSD
								September 28, 2008							       BSD