At present if a device to map has a block size other than 512,
the blkmap map process just fails. There is no reason why we
can't just use the block size of the mapped device.

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

These 2 are only used in drivers/block/blkmap.c.

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

Avoid using the magic number 512 directly.

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

Allow a slice of an existing block device to be mapped to a
blkmap. This means that filesystems that are not stored at exact
partition boundaries can be accessed by remapping a slice of the
existing device to a blkmap device.

Signed-off-by: Tobias Waldekranz <tobias@waldekranz.com>
Reviewed-by: Simon Glass <sjg@chromium.org>

Allow a slice of RAM to be mapped to a blkmap. This means that RAM can
now be accessed as if it was a block device, meaning that existing
filesystem drivers can now be used to access ramdisks.

Signed-off-by: Tobias Waldekranz <tobias@waldekranz.com>
Reviewed-by: Simon Glass <sjg@chromium.org>

blkmaps are loosely modeled on Linux's device mapper subsystem. The
basic idea is that you can create virtual block devices whose blocks
can be backed by a plethora of sources that are user configurable.

This change just adds the basic infrastructure for creating and
removing blkmap devices. Subsequent changes will extend this to add
support for actual mappings.

Signed-off-by: Tobias Waldekranz <tobias@waldekranz.com>
Reviewed-by: Simon Glass <sjg@chromium.org>