This command shows the memory used by driver model along with various
hints as to what it might be if some 'core' tags were moved to use the
tag list instead of a core (i.e. always-there) pointer.

This may help with future work to reduce memory usage.

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

Add a function for collecting the amount of memory used by driver model,
including devices, uclasses and attached data and tags.

This information can provide insights into how to reduce the memory
required by driver model. Future work may look at execution speed also.

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

At present tag numbers are only allocated for non-core data, meaning that
the 'core' data, like priv and plat, are accessed through dedicated
functions.

For debugging and consistency it is convenient to use tags for this 'core'
data too. Add support for this, with new tag numbers and functions to
access the pointer and size for each.

Update one of the test drivers so that the uclass-private data can be
tested here.

There is some code duplication with functions like device_alloc_priv() but
this is not addressed for now. At some point, some rationalisation may
help to reduce code size, but more thought it needed on that.

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

With dm-tag feature, any U-Boot subsystem is allowed to associate
arbitrary number of data with a particular udevice. This can been
see as expanding "struct udevice" without modifying the definition.

As a first user, UEFI subsystem makes use of tags to associate
an efi_disk object with a block device.

Signed-off-by: AKASHI Takahiro <takahiro.akashi@linaro.org>
Reviewed-by: Simon Glass <sjg@chromium.org>