Allow optionally set the logical block size of the host device to
bind in the "host bind" command. If not given, defaults to 512.

Signed-off-by: Bin Meng <bmeng@tinylab.org>

The documentation of struct host_ops should be Sphinx compliant.

Fixes: 9bd1aa8af2ed ("dm: sandbox: Create a new HOST uclass")
Signed-off-by: Heinrich Schuchardt <heinrich.schuchardt@canonical.com>

Sandbox supports block devices which can access files on the host machine.
At present there is no uclass for this. The devices are attached to the
root devic. The block-device type is therefore set to UCLASS_ROOT which
is confusing.

Block devices should be attached to a 'media' device instead, something
which handles access to the actual media and provides the block driver
for the block device.

Create a new uclass to handle this. It supports two operations, to attach
and detach a file on the host machine.

For now this is not fully plumbed in.

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