[PATCH RFC v2 0/8] tee: optee: add RPMI backend support on RISC-V

[Jens Wiklander]

Hi Amir,

On Tue, Oct 6, 2026 at 2:39 AM Amirreza Zarrabi
<amirreza.zarrabi at oss.qualcomm.com> wrote:
>
> This series adds an RPMI backend to the OP-TEE driver for RISC-V.
> It builds on the separately posted RPMI TEE transport series [1],
> which provides service discovery, synchronous calls, memory parcels
> and asynchronous signals.
>
> This revision is effectively a full rewrite of the original RFC.
> The generic RPMI transport has been separated from the OP-TEE backend,
> and the backend has been reworked around the service bus and a new
> OP-TEE control ABI.
>
> Unlike v1, the OP-TEE backend no longer manages SBI MPXY mailbox
> channels or implements RPMI TEE service-group operations directly.
> It binds to the OP-TEE service UUID on the RPMI TEE bus and uses the
> transport's public operations. No additional OP-TEE device-tree node
> is required.
>
> The backend reuses the common OP-TEE session, shared-memory, argument
> cache, call queue and RPC infrastructure. Shared memory is represented
> by RPMI parcel IDs and nonces. Yielding calls pass command and RPC
> buffer ranges within a parcel and resume suspended execution using
> an opaque token returned by OP-TEE.
>
> The OP-TEE control ABI uses fixed-width little-endian messages carried
> in TEE_CALL payloads rather than reproducing FF-A's register-based
> message layout. Asynchronous notifications use an allocated TEE-to-REE
> signal as a bottom-half doorbell, while ordinary logical notifications
> continue through the common RPC path.
>
> Matching OP-TEE OS support for this ABI has not yet been implemented.
> This remains an RFC for review of the backend integration and the
> Linux-to-OP-TEE protocol.
>
> [1] RPMI TEE transport dependency:
> https://lore.kernel.org/op-tee/20260928-riscv-rpmi-tee-abi-v1-0-04908b81d885@oss.qualcomm.com/
>
> Signed-off-by: Amirreza Zarrabi <amirreza.zarrabi at oss.qualcomm.com>
> ---
> Changes in v2:
> - Effectively rewrite the backend around the separately posted RPMI
>   TEE transport and a new OP-TEE control ABI.
> - Remove backend-owned per-hart mailbox channels and the OP-TEE-specific
>   device-tree binding.
> - Replace the register-like control payload with fixed-width messages,
>   explicit command/RPC buffer ranges and opaque resume tokens.
> - Add a parcel-reference parameter layout carrying the parcel ID,
>   nonce, and 64-bit offset and size without changing parameter size.
> - Make argument-offset support part of the baseline ABI and retain
>   the common shared argument cache.
> - Use a transport-allocated signal for asynchronous bottom-half
>   notifications.
> - Link to v1: https://lore.kernel.org/r/20260912-rpmi-tee-service-grp-dev-v1-0-1d1d35c2a859@oss.qualcomm.com
>
> ---
> Amirreza Zarrabi (8):
>       tee: optee: allow RPMI transport builds on RISC-V
>       tee: optee: define the RPMI control and parcel-reference ABI
>       tee: optee: add RPMI shared-memory and parameter support
>       tee: optee: add RPMI dynamic shared-memory pool
>       tee: optee: add RPMI RPC handling
>       tee: optee: execute yielding RPMI calls
>       tee: optee: bind RPMI services and negotiate backend capabilities
>       tee: optee: support RPMI asynchronous notification doorbells
>
>  drivers/tee/Kconfig               |    3 +-
>  drivers/tee/optee/Kconfig         |    3 +-
>  drivers/tee/optee/Makefile        |    1 +
>  drivers/tee/optee/call.c          |    2 +
>  drivers/tee/optee/core.c          |   10 +-
>  drivers/tee/optee/optee_msg.h     |   38 +-
>  drivers/tee/optee/optee_private.h |   54 +-
>  drivers/tee/optee/optee_rpmi.h    |  234 ++++++++
>  drivers/tee/optee/rpmi_abi.c      | 1059 +++++++++++++++++++++++++++++++++++++
>  9 files changed, 1389 insertions(+), 15 deletions(-)

The rpmi changes in the optee driver harmonize quite well with the
rest of the driver, but there are two things I'd like fixed:
- avoid <linux/cleanup.h> macros. They are distracting.
- use rc for the trivial int ERRNO values.

I would be great with a QEMU-based end-to-end prototype to demonstrate
that the ABI works.

More comments to come in the individual patches.

Cheers,
Jens