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Diffstat (limited to 'roms/u-boot/doc/usage/button.rst')
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diff --git a/roms/u-boot/doc/usage/button.rst b/roms/u-boot/doc/usage/button.rst new file mode 100644 index 000000000..ea4176275 --- /dev/null +++ b/roms/u-boot/doc/usage/button.rst @@ -0,0 +1,64 @@ +.. SPDX-License-Identifier: GPL-2.0+ + +button command +============== + +Synopsis +-------- + +:: + + button list + button <name> + +Description +----------- + +The button command is used to retrieve the status of a button. To show the +status of a button with name 'button1' you would issue the command + +:: + + button button1 + +The status of the button is both written to the console as *ON* or *OFF* and +set in the return value variable *$?* as 0 (true) or 1 (false). To retrieve +the status of a button with name *button1* and to write it to environment +variable *status1* you would execute the commands + +:: + + button button1 + setenv status1 $? + +A list of all available buttons and their status can be displayed using + +:: + + button list + +If a button device has not been probed yet, its status will be shown as +*<inactive>* in the list. + +Configuration +------------- + +To use the button command you must specify CONFIG_CMD_BUTTON=y and enable a +button driver. The available buttons are defined in the device-tree. + +Return value +------------ + +The variable *$?* takes the following values + ++---+-----------------------------+ +| 0 | ON, the button is pressed | ++---+-----------------------------+ +| 1 | OFF, the button is released | ++---+-----------------------------+ +| 0 | button list was shown | ++---+-----------------------------+ +| 1 | button not found | ++---+-----------------------------+ +| 1 | invalid arguments | ++---+-----------------------------+ |