doc:eficonfig: add documentation for eficonfig command

Add documentation for eficonfig command.

Signed-off-by: Masahisa Kojima <masahisa.kojima@linaro.org>
Reviewed-by: Ilias Apalodimas <ilias.apalodimas@linaro.org>

doc/usage/cmd/eficonfig.rst

@@ -0,0 +1,71 @@
+.. SPDX-License-Identifier: GPL-2.0+
+.. (C) Copyright 2022, Masahisa Kojima <masahisa.kojima@linaro.org>
+
+eficonfig command
+=================
+
+Synopsis
+--------
+::
+
+    eficonfig
+
+Description
+-----------
+
+The "eficonfig" command uses U-Boot menu interface and provides
+a menu-driven UEFI variable maintenance feature.
+The "eficonfig" has the following menu entries.
+
+Add Boot Option
+    Add new UEFI Boot Option.
+    User can edit description, file path, and optional_data.
+
+Edit Boot Option
+    Edit the existing UEFI Boot Option
+    User can edit description, file path, and optional_data.
+
+Change Boot Order
+    Change the order of UEFI BootOrder variable.
+
+Delete Boot Option
+    Delete the UEFI Boot Option
+
+Configuration
+-------------
+
+The "eficonfig" command is enabled by::
+
+    CONFIG_CMD_EFICONFIG=y
+
+If CONFIG_BOOTMENU_DISABLE_UBOOT_CONSOLE is enabled, user can not enter
+U-Boot console. In this case, bootmenu can be used to invoke "eficonfig"::
+
+    CONFIG_USE_PREBOOT=y
+    CONFIG_PREBOOT="setenv bootmenu_0 UEFI Maintenance Menu=eficonfig"
+
+How to boot the system with newly added UEFI Boot Option
+''''''''''''''''''''''''''''''''''''''''''''''''''''''''
+
+"eficonfig" command is responsible for configuring the UEFI variables,
+not directly handle the system boot.
+The new Boot Option added by "eficonfig" is appended at the last entry
+of UEFI BootOrder variable, user may want to change the boot order
+through "Change Boot Order".
+If the bootmenu is enabled, CONFIG_BOOTMENU_DISABLE_UBOOT_CONSOLE is enabled,
+and "eficonfig" is configured as preboot command, the newly added Boot Options
+are enumerated in the bootmenu when user exits from the eficonfig menu.
+User may select the entry in the bootmenu to boot the system, or follow
+the U-Boot configuration the system already has.
+
+Auto boot with the UEFI Boot Option
+'''''''''''''''''''''''''''''''''''
+
+To do auto boot according to the UEFI BootOrder variable,
+add "bootefi bootmgr" entry as a default or first bootmenu entry::
+
+    CONFIG_PREBOOT="setenv bootmenu_0 UEFI Boot Manager=bootefi bootmgr; setenv bootmenu_1 UEFI Maintenance Menu=eficonfig"
+
+See also
+--------
+* :doc:`bootmenu<bootmenu>` provides a simple mechanism for creating menus with different boot items

doc/usage/index.rst

@@ -35,6 +35,7 @@ Shell commands
    cmd/conitrace
    cmd/dm
    cmd/echo
+   cmd/eficonfig
    cmd/env
    cmd/event
    cmd/exception