Merge branch '2023-08-25-add-persistent-config-editor-via-expo' into next

To quote the author:
So far cedit does not support reading and writing the configuration.
This series add several features related to this:

First, it adds support for using a file on a filesystem. This is in
FDT format and provides enough information to reset the cedit back to
the saved settings.

Second, it adds support for using the U-Boot environment. Since the
environment is generally saved across reboots, this feature provides an
easy way of storing the state on most boards. The variables all have a
'c.' prefix to avoid confusion with other variables.

Finally it adds support for using CMOS RAM. This is commonly used on x86
devices to store BIOS settings. The expo schema provides information on
the register layout.

Some other minor tweaks and improvements are included along the way.

1 files changed, 117 insertions, 0 deletions

diff --git a/doc/usage/cmd/cedit.rst b/doc/usage/cmd/cedit.rst
index 8e1110c7c77..f415b48699e 100644
--- a/doc/usage/cmd/cedit.rst
+++ b/doc/usage/cmd/cedit.rst
@@ -10,6 +10,11 @@ Synopis
 
     cedit load <interface> <dev[:part]> <filename>
     cedit run
+    cedit write_fdt <dev[:part]> <filename>
+    cedit read_fdt <dev[:part]> <filename>
+    cedit write_env [-v]
+    cedit read_env [-v]
+    cedit write_cmos [-v] [dev]
 
 Description
 -----------
@@ -22,6 +27,69 @@ It makes use of the expo subsystem.
 The description is in the form of a devicetree file, as documented at
 :ref:`expo_format`.
 
+See :doc:`../../develop/cedit` for information about the configuration editor.
+
+cedit load
+~~~~~~~~~~
+
+Loads a configuration-editor description from a file. It creates a new cedit
+structure ready for use. Initially no settings are read, so default values are
+used for each object.
+
+cedit run
+~~~~~~~~~
+
+Runs the default configuration-editor event loop. This is very simple, just
+accepting character input and moving through the objects under user control.
+The implementation is at `cedit_run()`.
+
+cedit write_fdt
+~~~~~~~~~~~~~~~
+
+Writes the current user settings to a devicetree file. For each menu item the
+selected ID and its text string are written.
+
+cedit read_fdt
+~~~~~~~~~~~~~~
+
+Reads the user settings from a devicetree file and updates the cedit with those
+settings.
+
+cedit read_env
+~~~~~~~~~~~~~~
+
+Reads the settings from the environment variables. For each menu item `<name>`,
+cedit looks for a variable called `c.<name>` with the ID of the selected menu
+item.
+
+The `-v` flag enables verbose mode, where each variable is printed after it is
+read.
+
+cedit write_env
+~~~~~~~~~~~~~~~
+
+Writes the settings to environment variables. For each menu item the selected
+ID and its text string are written, similar to:
+
+   setenv c.<name> <selected_id>
+   setenv c.<name>-str <selected_id's text string>
+
+The `-v` flag enables verbose mode, where each variable is printed before it is
+set.
+
+cedit write_cmos
+~~~~~~~~~~~~~~~~
+
+Writes the settings to locations in the CMOS RAM. The locations used are
+specified by the schema. See `expo_format_`.
+
+The `-v` flag enables verbose mode, which shows which CMOS locations were
+updated.
+
+Normally the first RTC device is used to hold the data. You can specify a
+different device by name using the `dev` parameter.
+
+
 Example
 -------
 
@@ -29,3 +97,52 @@ Example
 
     => cedit load hostfs - fred.dtb
     => cedit run
+    => cedit write_fdt hostfs - settings.dtb
+
+That results in::
+
+    / {
+        cedit-values {
+            cpu-speed = <0x00000006>;
+            cpu-speed-str = "2 GHz";
+            power-loss = <0x0000000a>;
+            power-loss-str = "Always Off";
+        };
+    }
+
+    => cedit read_fdt hostfs - settings.dtb
+
+This shows settings being stored in the environment::
+
+    => cedit write_env -v
+    c.cpu-speed=7
+    c.cpu-speed-str=2.5 GHz
+    c.power-loss=12
+    c.power-loss-str=Memory
+    => print
+    ...
+    c.cpu-speed=6
+    c.cpu-speed-str=2 GHz
+    c.power-loss=10
+    c.power-loss-str=Always Off
+    ...
+
+    => cedit read_env -v
+    c.cpu-speed=7
+    c.power-loss=12
+
+This shows writing to CMOS RAM. Notice that the bytes at 80 and 84 change::
+
+    => rtc read 80 8
+    00000080: 00 00 00 00 00 2f 2a 08                          ...../*.
+    =>  cedit write_cmos -v
+    Write 2 bytes from offset 80 to 84
+    => rtc read 80 8
+    00000080: 01 00 00 00 08 2f 2a 08                          ...../*.
+    => cedit read_cmos -v
+    Read 2 bytes from offset 80 to 84
+
+Here is an example with the device specified::
+
+    => cedit write_cmos rtc@43
+    =>