Use the -l flag to indicate whether to report missing uclasses.

Also try to be more helpful when no devices are found. For example, when
we see something 'scsi0' requested and nothing was found, this indicates
that there are no SCSI devices, so show a suitable message.

Move messages out of the low-level functions so that silent operation
is possible.

This means they are never reported unless BOOTSTD_FULL is enabled, since
the -l flag cannot otherwise be set.

Suggested-by: Tom Rini <trini@konsulko.com>

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

We want to support scanning a single label, like 'mmc' or 'usb0'. Add
this feature by plumbing the label through to the iterator, setting a
flag to indicate that only siblings of the initial device should be used.

This means that scanning a bootdev by its name is not supported anymore.
That feature doesn't seem very useful in practice, so it is no great loss.

Add a test for bootdev_find_by_any() while we are here.

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

At present we set up the bootdev order at the start, then scan the
bootdevs one by one.

However this approach cannot be used with hunters, since the bootdevs may
not exist until the hunter is used. Nor can we just run all the hunters at
the start, since that violate's U-Boot's 'lazy init' requirement. It also
increases boot time.

So we need to adjust the algorithm to scan by labels instead. As a first
step, drop the dev_order[] array in favour of a list of labels. Update the
name of bootdev_setup_iter_order() to better reflect what it does.

Update some related comments and log messages. Also disable a few tests
until a later commit where we can use them.

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

Add a function which moves to the next priority to be processed.

This works by storing the current priority in the bootflow iterator. The
logic to set this up is included in a subsequent commit.

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

Add a function which moves to the next label in a list of labels. This
allows processing the boot_targets environment variable.

This works using a new label list in the bootflow iterator. The logic to
set this up is included in a subsequent commit.

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

Add a function to hunt for a bootdev label and find the bootdev produced
by the hunter (or already present).

Add a few extra flags so that we can distinguish between "mmc1", "mmc" and
"1" which all need to be handled differently.

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

We need extensions to be set up before we start trying to boot any of the
bootdevs. Add a new priority before all the others for tht sort of thing.
Also add a 'none' option, so that the first one is not 0.

While we are here, comment enum bootdev_prio_t fully and expand the test
for the 'bootdev hunt' command.

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

Add a way to run the hunter function for a particular priority, so that
new bootdevs can be found.

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

These are associated with the ethernet boot device but do not match its
uclass name, so handle them as special cases.

Provide a way to pass flags through with the bootdev so that we know
how to process it. The flags are checked by the bootmeths, to ensure that
only the selected bootmeth is used.

While these both use the network device, they work quite differently. It
is common to run only one of these, or to run PXE before DHCP. Provide
bootflow flags to control which methods are used. Check these in the two
bootmeths so that only the chosen one is used.

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

Add a way to run a bootdev hunter to find bootdevs of a certain type. Add
this to the 'bootdev hunt' command. Test for this are added in a later
patch, since a useful test needs some hunters to work with.

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