1 .. SPDX-License-Identifier: GPL-2.0
2
3 .. _GPIO_V2_GET_LINEINFO_WATCH_IOCTL:
4
5 ********************************
6 GPIO_V2_GET_LINEINFO_WATCH_IOCTL
7 ********************************
8
9 Name
10 ====
11
12 GPIO_V2_GET_LINEINFO_WATCH_IOCTL - Enable watc
13 request state and configuration information.
14
15 Synopsis
16 ========
17
18 .. c:macro:: GPIO_V2_GET_LINEINFO_WATCH_IOCTL
19
20 ``int ioctl(int chip_fd, GPIO_V2_GET_LINEINFO_
21
22 Arguments
23 =========
24
25 ``chip_fd``
26 The file descriptor of the GPIO character
27
28 ``info``
29 The :c:type:`line_info<gpio_v2_line_info>`
30 the ``offset`` set to indicate the line to
31
32 Description
33 ===========
34
35 Enable watching a line for changes to its requ
36 information. Changes to line info include a li
37 or reconfigured.
38
39 .. note::
40 Watching line info is not generally requir
41 used by a system monitoring component.
42
43 The line info does NOT include the line va
44 The line must be requested using gpio-v2-g
45 its value, and the line request can monito
46 gpio-v2-line-event-read.rst.
47
48 By default all lines are unwatched when the GP
49
50 Multiple lines may be watched simultaneously b
51
52 Once a watch is set, any changes to line info
53 read from the ``chip_fd`` as described in
54 gpio-v2-lineinfo-changed-read.rst.
55
56 Adding a watch to a line that is already watch
57
58 Watches are specific to the ``chip_fd`` and ar
59 on the same GPIO chip opened with a separate c
60
61 Return Value
62 ============
63
64 On success 0 and ``info`` is populated with th
65
66 On error -1 and the ``errno`` variable is set
67 Common error codes are described in error-code
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