DESCRIPTION

     The register_chrdev function associates  a  character  major
     number  with set of driver entry points. The file_operations
     structure contains pointers to functions that the the driver
     uses to implement the kernel interface to the driver.

     The paramter major is the character major number assigned to
     the  device  driver  and to be mapped to the function table.
     The name parameter is a short name for  the  device  and  is
     displayed  in  the  The  /proc/devices  list.  It  also must
     exactly match the name passed to unregister_chrdev  function
     when releasing the functions.

     A device driver module may register as many different  major
     numbers as it supports, though this is not typically done.

     The unregister_chrdev function releases  the  major  number,
     and  is  normally  called  in the module_cleanup function to
     remove the driver from the kernel.

RETURN VALUE

     On success, register_chrdev returns 0 if major is  a  number
     other then 0, otherwise Linux will choose a major number and
     return the chosen value.

     If there is an error, one of the following codes is returned
     instead:

          -EINVAL
               The specified number is not valid (> MAX_CHRDEV)

          -EBUSY
               The major number is busy

     The unregister_chrdev function will return 0 if  successful,
     or  -EINVAL  if  the major number is not registered with the
     matching name.

AVAILABILITY

     Linux 1.0+

SEE ALSO

     register_blkdev(9) mknod(2)

AUTHOR

     Stephen Williams (steve@icarus.com)

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