In some cases it is necessary to pass parameters to Linux so that it will
boot correctly. For example, the rootdev parameter is often used to
specify the root device. However the root device may change depending on
whence U-Boot loads the kernel. At present it is necessary to build up
the command line by adding device strings to it one by one.

It is often more convenient to provide a template for bootargs, with
U-Boot doing the substitution from other environment variables.

Add a way to substitute strings in the bootargs variable. This allows
things like "rootdev=${rootdev}" to be used in bootargs, with the
${rootdev} substitution providing the UUID of the root device.

For example, to substitute the GUID of the kernel partition:

  setenv bootargs "console=/dev/ttyS0 rootdev=${uuid}/PARTNROFF=1
		kern_guid=${uuid}"
  part uuid mmc 2:2 uuid
  bootm

This is particularly useful when the command line from another place. For
example, Chrome OS stores the command line next to the kernel itself. It
depends on the kernel version being used as well as the hardware features,
so it is extremely difficult to devise a U-Boot script that works on all
boards and kernel versions. With this feature, the command line can be
read from disk and used directly, with a few substitutions set up.

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

At present we only support updating the 'bootargs' environment
variable. Add another function to update a buffer instead. This will
allow zimage to use this feature.

Also add a lot more tests to cover various cases.

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

At present only one transformation is supported: making the Linux console
silent. To prepare for adding more, convert the boolean parameter into a
flag value.

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

This function will soon do more than just handle the 'silent linux'
feature. As a first step, update it to take a boolean parameter,
indicating whether or not the processing is required.

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

We want to add more processing to this function. Before doing so, rename
it to bootm_process_cmdline_env(), which is more generic.

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

At present this function fails silently on error. Update it to produce
an error code. Report this error to the user and abort the boot, since it
likely will prevent a successful start.

No tests are added at this stage, since additional refactoring is taking
place in subsequent patches.

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

This function currently has no tests. Export it so that we can implement
a simple test on sandbox. Use IS_ENABLED() to remove the unused code,
instead #ifdef.

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

Functions that are used in multiple C modules should be defined in an
include.

Signed-off-by: Heinrich Schuchardt <xypron.glpk@gmx.de>
Reviewed-by: Michael Walle <michael@walle.cc>

These cases are typically fatal and are difficult to debug for random
users. Add checks for detecting overlapping images and abort if overlap
is detected.

Signed-off-by: Tero Kristo <t-kristo@ti.com>

We should not use typedefs in U-Boot. They cannot be used as forward
declarations which means that header files must include the full header to
access them.

Drop the typedef and rename the struct to remove the _s suffix which is
now not useful.

This requires quite a few header-file additions.

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