SPDX-License-Identifier: CC-BY-SA-4.0 OR BSD-2-Clause
brief: |
  Controls the device specified by the device major and minor numbers.
copyrights:
- Copyright (C) 2020 embedded brains GmbH & Co. KG
- Copyright (C) 1988, 2008 On-Line Applications Research Corporation (OAR)
definition:
  default:
    attributes: null
    body: null
    params:
    - ${device-major-number:/name} ${.:/params[0]/name}
    - ${device-minor-number:/name} ${.:/params[1]/name}
    - void *${.:/params[2]/name}
    return: ${../../status/if/code:/name}
  variants: []
description: |
  This directive calls the device driver I/O control entry registered in the
  Device Driver Table for the specified device major number.
enabled-by: true
index-entries:
- IO control
- special device services
interface-type: function
links:
- role: interface-placement
  uid: header
- role: interface-ingroup
  uid: group
- role: constraint
  uid: /constraint/directive-not-pre-qualified
name: rtems_io_control
notes: |
  The exact functionality of the driver entry called by this directive is
  driver dependent.  It should not be assumed that the control entries of two
  device drivers are compatible.  For example, an RS-232 driver I/O control
  operation may change the baud of a serial line, while an I/O control
  operation for a floppy disk driver may cause a seek operation.
params:
- description: |
    is the major number of the device.
  dir: null
  name: major
- description: |
    is the minor number of the device.
  dir: null
  name: minor
- description: |
    is the argument passed to the device driver I/O control entry.
  dir: null
  name: argument
return:
  return: |
    Other status codes may be returned by the device driver I/O control
    entry.
  return-values:
  - description: |
      The requested operation was successful.
    value: ${../../status/if/successful:/name}
  - description: |
      The device major number was invalid.
    value: ${../../status/if/invalid-number:/name}
type: interface