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34e452dd02
Currently all shell command docs are put in the doc/usage root. Let's group them into cmd/ sub-directory. Signed-off-by: Bin Meng <bmeng.cn@gmail.com> Reviewed-by: Heinrich Schuchardt <heinrich.schuchardt@canonical.com>
64 lines
1.4 KiB
ReStructuredText
64 lines
1.4 KiB
ReStructuredText
.. SPDX-License-Identifier: GPL-2.0+
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button command
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==============
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Synopsis
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--------
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::
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button list
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button <name>
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Description
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-----------
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The button command is used to retrieve the status of a button. To show the
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status of a button with name 'button1' you would issue the command
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::
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button button1
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The status of the button is both written to the console as *ON* or *OFF* and
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set in the return value variable *$?* as 0 (true) or 1 (false). To retrieve
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the status of a button with name *button1* and to write it to environment
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variable *status1* you would execute the commands
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::
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button button1
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setenv status1 $?
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A list of all available buttons and their status can be displayed using
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::
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button list
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If a button device has not been probed yet, its status will be shown as
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*<inactive>* in the list.
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Configuration
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-------------
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To use the button command you must specify CONFIG_CMD_BUTTON=y and enable a
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button driver. The available buttons are defined in the device-tree.
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Return value
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------------
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The variable *$?* takes the following values
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+---+-----------------------------+
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| 0 | ON, the button is pressed |
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+---+-----------------------------+
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| 1 | OFF, the button is released |
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+---+-----------------------------+
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| 0 | button list was shown |
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+---+-----------------------------+
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| 1 | button not found |
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+---+-----------------------------+
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| 1 | invalid arguments |
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+---+-----------------------------+
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