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"Das U-Boot" Source Tree
1.. SPDX-License-Identifier: GPL-2.0+
2
3.. index::
4 single: button (command)
5
6button command
7==============
8
9Synopsis
10--------
11
12::
13
14 button list
15 button <name>
16
17Description
18-----------
19
20The button command is used to retrieve the status of a button. To show the
21status of a button with name 'button1' you would issue the command
22
23::
24
25 button button1
26
27The status of the button is both written to the console as *ON* or *OFF* and
28set in the return value variable *$?* as 0 (true) or 1 (false). To retrieve
29the status of a button with name *button1* and to write it to environment
30variable *status1* you would execute the commands
31
32::
33
34 button button1
35 setenv status1 $?
36
37A list of all available buttons and their status can be displayed using
38
39::
40
41 button list
42
43If a button device has not been probed yet, its status will be shown as
44*<inactive>* in the list.
45
46Configuration
47-------------
48
49To use the button command you must specify CONFIG_CMD_BUTTON=y and enable a
50button driver. The available buttons are defined in the device-tree.
51
52Return value
53------------
54
55The variable *$?* takes the following values
56
57+---+-----------------------------+
58| 0 | ON, the button is pressed |
59+---+-----------------------------+
60| 1 | OFF, the button is released |
61+---+-----------------------------+
62| 0 | button list was shown |
63+---+-----------------------------+
64| 1 | button not found |
65+---+-----------------------------+
66| 1 | invalid arguments |
67+---+-----------------------------+