1 .. SPDX-License-Identifier: GPL-2.0
2
3 .. _GPIO_GET_LINEEVENT_IOCTL:
4
5 ************************
6 GPIO_GET_LINEEVENT_IOCTL
7 ************************
8
9 .. warning::
10 This ioctl is part of chardev_v1.rst and i
11 gpio-v2-get-line-ioctl.rst.
12
13 Name
14 ====
15
16 GPIO_GET_LINEEVENT_IOCTL - Request a line with
17
18 Synopsis
19 ========
20
21 .. c:macro:: GPIO_GET_LINEEVENT_IOCTL
22
23 ``int ioctl(int chip_fd, GPIO_GET_LINEEVENT_IO
24
25 Arguments
26 =========
27
28 ``chip_fd``
29 The file descriptor of the GPIO character
30
31 ``request``
32 The :c:type:`event_request<gpioevent_reque
33 to request and its configuration.
34
35 Description
36 ===========
37
38 Request a line with edge detection from the ke
39
40 On success, the requesting process is granted
41 value and may receive events when edges are de
42 described in gpio-lineevent-data-read.rst.
43
44 The state of a line is guaranteed to remain as
45 file descriptor is closed. Once the file descr
46 the line becomes uncontrolled from the userspa
47 to its default state.
48
49 Requesting a line already in use is an error (
50
51 Requesting edge detection on a line that does
52 error (**ENXIO**).
53
54 As with the :ref:`line handle<gpio-get-linehan
55 bias configuration is best effort.
56
57 Closing the ``chip_fd`` has no effect on exist
58
59 Configuration Rules
60 -------------------
61
62 The following configuration rules apply:
63
64 The line event is requested as an input, so no
65 ``GPIOHANDLE_REQUEST_OUTPUT``, ``GPIOHANDLE_RE
66 ``GPIOHANDLE_REQUEST_OPEN_SOURCE``, may be set
67
68 Only one bias flag, ``GPIOHANDLE_REQUEST_BIAS_
69 If no bias flags are set then the bias configu
70
71 The edge flags, ``GPIOEVENT_REQUEST_RISING_EDG
72 ``GPIOEVENT_REQUEST_FALLING_EDGE``, may be com
73 and falling edges.
74
75 Requesting an invalid configuration is an erro
76
77 Return Value
78 ============
79
80 On success 0 and the :c:type:`request.fd<gpioe
81 descriptor for the request.
82
83 On error -1 and the ``errno`` variable is set
84 Common error codes are described in error-code
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