Changes implementation when using TEE dynamically allocated shared
memory to synchronize with the Linux implementation where the legacy
SMT protocol cannot be used with such memory since it is expected from
device mapped memory whereas OP-TEE shared memory is cached and
hence should not be accessed using memcpy_toio()/memcpy_fromio().
This change implements the MSG shared memory protocol introduced
in Linux [1]. The protocol uses a simplified SMT header of 32bit
named MSG_SMT to carry SCMI protocol information and uses side channel
means to carry exchanged buffer size information, as TEE invocation API
parameters when used in the SCMI OP-TEE transport.
Link: [1] https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?id=f301bba0ca7392d16a6ea4f1d264a91f1fadea1a
Signed-off-by: Etienne Carriere <etienne.carriere@linaro.org>
This change implements an SCMI transport for agent interfacing the
OP-TEE SCMI service. OP-TEE provides an SCMI PTA (Pseudo-TA) for
non-secure world to send SCMI messages over an identified channel.
The driver implemented here uses a SMT shared memory for passing
messages between client and server.
The implementation opens and releases channel resources for each
passed SCMI message so that resources allocated (sessions) or
registered (shared memory areas) in OP-TEE firmware are released for
example before relocation as the driver will likely allocate/register
them back when probed after relocation.
The integration of the driver using dedicated config switch
CONFIG_SCMI_AGENT_OPTEE is designed on the model posted to the
U-Boot ML by Patrick Delaunay [1].
Link: [1] https://lore.kernel.org/all/20211028191222.v3.4.Ib2e58ee67f4d023823d8b5404332dc4d7e847277@changeid/
Cc: Patrick Delaunay <patrick.delaunay@foss.st.com>
Cc: Wolfgang Denk <wd@denx.de>
Signed-off-by: Etienne Carriere <etienne.carriere@linaro.org>
Reviewed-by: Patrick Delaunay <patrick.delaunay@foss.st.com>
