Some Linux parameters can be set automatically by U-Boot, if it knows the
device being used. For example, since U-Boot knows the serial console
being used, it can add parameters for earlycon and console.

Add support for this.

Note that this is an experimental feature and we will see how useful it
turns out to be. It is very handy for ChromeOS, since otherwise it is very
difficult to manually determine the UART address or port number,
particularly in a script.

Provide an example of how this is used with ChromeOS.

Signed-off-by: Simon Glass <sjg@chromium.org>
Reviewed-by: Bin Meng <bmeng.cn@gmail.com>

Add a bootflow command to update the command line more easily. This allows
changing a particular parameter rather than editing a very long strings.
It is also easier to handle with scripting.

The new 'bootflow cmdline' command allows getting and setting single
parameters.

Fix up the example output while we are here, since there are a few new
items.

Signed-off-by: Simon Glass <sjg@chromium.org>
Reviewed-by: Bin Meng <bmeng.cn@gmail.com>

On x86 boards Linux uses a block of binary data to provide information
about the command line, memory map, etc. Provide a way to store this in
the bootflow so it can be passed on to the OS.

No attempt is made to generalise the code, since other archs don't need
this information. The field is present always, though, to avoid needing
accessors or #ifdefs when building code on other archs.

Signed-off-by: Simon Glass <sjg@chromium.org>
Reviewed-by: Bin Meng <bmeng.cn@gmail.com>

The "bootargs" environment variable is used to set the command-line
arguments to pass to the OS. Use this same mechanism with bootstd as well.
When the variable is updated, it is written to the current bootflow. When
the current bootflow is updated, the environment variable is updated too.

Signed-off-by: Simon Glass <sjg@chromium.org>
Reviewed-by: Bin Meng <bmeng.cn@gmail.com>

Some operating systems have a command line which can be adjusted before
booting. Store this in the bootflow so it can be controlled within
U-Boot.

Fix up the example output while we are here, since there are a few new
items.

Signed-off-by: Simon Glass <sjg@chromium.org>
Reviewed-by: Bin Meng <bmeng.cn@gmail.com>

In a few cases the error handling is not quite right. Make sure we
return the actual error in distro_efi_read_bootflow_file() rather than
-EINVAL. Return -IO when a file cannot be read. Also show the error name
if available.

This does not change operation, but does make it easier to diagnose
problems.

Signed-off-by: Simon Glass <sjg@chromium.org>

The patch to relax flag requirements was not accepted[1], so we still have
to have separate bootcommands depending on CMD_BOOTFLOW_FULL.

The previous attempt at this did not work, since it used the wrong name
for the options.

Fix this and change the message to mention BOOTSTD_FULL since this affects
not just the flags, but all functionality, so is more likely what the user
wants.

Drop the useless condition on CMD_BOOTFLOW_FULL while we are here.

[1] https://patchwork.ozlabs.org/project/uboot/patch/20230329071655.1959513-2-sjg@chromium.org/

Signed-off-by: Simon Glass <sjg@chromium.org>
Fixes: a91492b6e9c ("bootstd: Provide a default command")

When building this with clang, we get a warning such as:
cmd/bootflow.c:412:27: warning: variable 'bflow' is uninitialized when used here [-Wuninitialized]
        printf("Selected: %s\n", bflow->os_name ? bflow->os_name : bflow->name);
                                 ^~~~~

And a suggestion to just initialize bflow to NULL. This would however
would be ensuring a bad dereference. Instead, looking at the function we
rework things so that when CONFIG_EXPO is not enabled (and so, no UI) we
error early and would never reach this point in the code.  Simplify the
rest slightly as well while at this.

Signed-off-by: Tom Rini <trini@konsulko.com>
Reviewed-by: Simon Glass <sjg@chromium.org>

Enable some messages that might provide hints, but only for
CMD_BOOTFLOW_FULL since otherwise the -l flag is not available.

Signed-off-by: Simon Glass <sjg@chromium.org>
Suggested-by: Tom Rini <trini@konsulko.com>

These flags actually relate to the iterator, not the bootflow struct
itself. Rename them.

Signed-off-by: Simon Glass <sjg@chromium.org>