When there are no more bootdevs we should still go through the global
bootmeths, since some may not have yet been used, if their priority has
not yet come up.

Add a final check for this at the end of the iterator.

Update the documentation to match the new behaviour of global bootmeths.

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

At present before scanning global bootmeths, the iterator sets the
method count to the index of the first global bootmeth. Now that we
support scanning the global bootmeths multiple times, we must leave this
count alone.

Check against have_global and first_glob_method instead.

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

Allow bootmeths to select when they want to run, using the bootdev
priority. Provide a new bootmeth_glob_allowed() function which checks if
a bootmeth is ready to use.

Fix a comment in bootflow_system() which is a test for global bootmeths.

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

Use the methods_done flags to make sure that each global bootmeth is
only used once. For now this has no effect, since they are all processed
at the start.

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

Add the logic to scan through the global bootmeths for every new
bootdev, in preparation for allowing global bootmeths to select where in
the hunter ordering they go.

Use a new bootmeth_glob_allowed() function to check if a bootmeth is
allowed, ensuring that each can run at most once.

For now this has no actual effect, since the global bootmeths are
unconditionally processed at the start, with iter->methods_done being
updated to include all of them. Therefore when scanning again, no
unprocessed global bootmeths will be found.

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

Add a bitfield which tracks when bootmeths have been used. This will be
needed when global bootmeths can be used later in the iteration.

Fix a missing bootflow_free() while here.

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

For now we only support dropping non-global bootmeths from the
iteration. Update first_glob_method in that case and add a few checks
that things are correct.

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

At present, normally when one bootmeth fails on a partition, we move on
and try the next bootmeth. However, this was not the case for the final
partition due to a bug. Rework the logic so that all partitions are
treated the same.

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

We will want to use this same logic in another place within iter_inc(),
so split it out into its own function.

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

Add a few comments about global bootmeths and first_glob_method

Signed-off-by: Simon Glass <sjg@chromium.org>
Reviewed-by: Heinrich Schuchardt <xypron.glpk@gmx.de>
Reviewed-by: Mattijs Korpershoek <mkorpershoek@kernel.org>
Reviewed-by: Sam Protsenko <semen.protsenko@linaro.org>