.. SPDX-License-Identifier: CC-BY-SA-4.0

.. Copyright (C) 1988, 2008 On-Line Applications Research Corporation (OAR)

Operations
==========

Register and Lookup Name
------------------------

The ``rtems_io_register`` directive associates a name with the specified device
(i.e. major/minor number pair).  Device names are typically registered as part
of the device driver initialization sequence.  The ``rtems_io_lookup``
directive is used to determine the major/minor number pair associated with the
specified device name.  The use of these directives frees the application from
being dependent on the arbitrary assignment of major numbers in a particular
application.  No device naming conventions are dictated by RTEMS.

Accessing an Device Driver
--------------------------

The I/O manager provides directives which enable the application program to
utilize device drivers in a standard manner.  There is a direct correlation
between the RTEMS I/O manager directives ``rtems_io_initialize``,
``rtems_io_open``, ``rtems_io_close``, ``rtems_io_read``, ``rtems_io_write``,
and ``rtems_io_control`` and the underlying device driver entry points.