A number of storage technologies support a specialised hardware
partition designed to be resistant to replay attacks. The underlying
HW protocols differ but the operations are common. The RPMB partition
cannot be accessed via standard block layer, but by a set of specific
RPMB commands. Such a partition provides authenticated and replay
protected access, hence suitable as a secure storage.

The initial aim of this patch is to provide a simple RPMB driver
interface which can be accessed by the optee driver to facilitate early
RPMB access to OP-TEE OS (secure OS) during the boot time.

A TEE device driver can claim the RPMB interface, for example, via
rpmb_interface_register() or rpmb_dev_find_device(). The RPMB driver
provides a callback to route RPMB frames to the RPMB device accessible
via rpmb_route_frames().

The detailed operation of implementing the access is left to the TEE
device driver itself.
Signed-off-by: Tomas Winkler <tomas.winkler@intel.com>
Signed-off-by: Alex Bennée <alex.bennee@linaro.org>
Signed-off-by: Shyam Saini <shyamsaini@linux.microsoft.com>
Signed-off-by: Jens Wiklander <jens.wiklander@linaro.org>
Reviewed-by: Linus Walleij <linus.walleij@linaro.org>
Tested-by: Manuel Traut <manut@mecka.net>
Reviewed-by: Ulf Hansson <ulf.hansson@linaro.org>
Reviewed-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Link: https://lore.kernel.org/r/20240814153558.708365-2-jens.wiklander@linaro.orgSigned-off-by: Ulf Hansson <ulf.hansson@linaro.org>