xref: /linux/Documentation/userspace-api/gpio/gpio-handle-set-config-ioctl.rst (revision 4b660dbd9ee2059850fd30e0df420ca7a38a1856)
1.. SPDX-License-Identifier: GPL-2.0
2
3.. _GPIOHANDLE_SET_CONFIG_IOCTL:
4
5***************************
6GPIOHANDLE_SET_CONFIG_IOCTL
7***************************
8
9.. warning::
10    This ioctl is part of chardev_v1.rst and is obsoleted by
11    gpio-v2-line-set-config-ioctl.rst.
12
13Name
14====
15
16GPIOHANDLE_SET_CONFIG_IOCTL - Update the configuration of previously requested lines.
17
18Synopsis
19========
20
21.. c:macro:: GPIOHANDLE_SET_CONFIG_IOCTL
22
23``int ioctl(int handle_fd, GPIOHANDLE_SET_CONFIG_IOCTL, struct gpiohandle_config *config)``
24
25Arguments
26=========
27
28``handle_fd``
29    The file descriptor of the GPIO character device, as returned in the
30    :c:type:`request.fd<gpiohandle_request>` by gpio-get-linehandle-ioctl.rst.
31
32``config``
33    The new :c:type:`configuration<gpiohandle_config>` to apply to the
34    requested lines.
35
36Description
37===========
38
39Update the configuration of previously requested lines, without releasing the
40line or introducing potential glitches.
41
42The configuration applies to all requested lines.
43
44The same :ref:`gpio-get-linehandle-config-rules` and
45:ref:`gpio-get-linehandle-config-support` that apply when requesting the
46lines also apply when updating the line configuration.
47
48The motivating use case for this command is changing direction of
49bi-directional lines between input and output, but it may be used more
50generally to move lines seamlessly from one configuration state to another.
51
52To only change the value of output lines, use
53gpio-handle-set-line-values-ioctl.rst.
54
55First added in 5.5.
56
57Return Value
58============
59
60On success 0.
61
62On error -1 and the ``errno`` variable is set appropriately.
63Common error codes are described in error-codes.rst.
64