Add submodule dependency filesHEADmaster

Change-Id: Iaf8d18082d3991dec7c0ebbea540f092188eb4ec

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diff --git a/roms/u-boot/doc/usage/button.rst b/roms/u-boot/doc/usage/button.rst
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+.. 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           |
++---+-----------------------------+