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>

The Linux command line consists of a number of words with optional values.
At present U-Boot allows this to be changed using the bootargs environment
variable.

But this is quite painful, since the command line can be very long.

Add a function which can adjust a single field in the command line, so
that it is easier to make changes before booting.

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>

It seems better to call this a 'bootdev' since this is name used in the
documentation. The older 'Bootdevice' name is no-longer used and may cause
confusion with the 'bootdevice' environment variable.

Update throughout to use bootdev.

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

For EFI, the distro boot scripts search in three different directories
for the .dtb file. The SOC-based filename fallback is supported only for
32-bit ARM.

Adjust the code to mirror this behaviour.

Also some boards can use a prior-stage FDT if one is not found in the
normal way. Support this and show a message in that case.

Signed-off-by: Simon Glass <sjg@chromium.org>
Suggested-by: Mark Kettenis <kettenis@openbsd.org>

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

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

This supports reading a kernel and ramdisk from qfw, then loading it with
either the booti or bootz commands.

For now this uses the existing booti and bootz commands, rather than
trying to call that functionality directly (e.g. do_bootm_states()). It
does not require the HUSH parser though, which helps a little with size.

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

In some cases the block device is obtained but is not probed, since it
is a sibling of the bootdev. Make sure it is probed, so it can be used
without any trouble.

This fixes a bug with virtio, where the device is accessed before it has
been set up by the virtio uclass.

Signed-off-by: Simon Glass <sjg@chromium.org>
Fixes: 201417d700a ("bootstd: Add the bootdev uclass")
Reported-by: Ilias Apalodimas <ilias.apalodimas@linaro.org>

Add some logging to aid debugging of problems with bootflows.

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