Add documentation for the Trusted Services TEE driver.
Signed-off-by: Balint Dobszay balint.dobszay@arm.com --- Documentation/tee/index.rst | 1 + Documentation/tee/ts-tee.rst | 70 ++++++++++++++++++++++++++++++++++++ 2 files changed, 71 insertions(+) create mode 100644 Documentation/tee/ts-tee.rst
diff --git a/Documentation/tee/index.rst b/Documentation/tee/index.rst index a23bd08847e5..4be6e69d7837 100644 --- a/Documentation/tee/index.rst +++ b/Documentation/tee/index.rst @@ -10,6 +10,7 @@ TEE Subsystem tee op-tee amd-tee + ts-tee
.. only:: subproject and html
diff --git a/Documentation/tee/ts-tee.rst b/Documentation/tee/ts-tee.rst new file mode 100644 index 000000000000..e121ebbbfab7 --- /dev/null +++ b/Documentation/tee/ts-tee.rst @@ -0,0 +1,70 @@ +.. SPDX-License-Identifier: GPL-2.0 + +================================= +TS-TEE (Trusted Services project) +================================= + +This driver provides access to secure services implemented by Trusted Services. + +Trusted Services [1] is a TrustedFirmware.org project that provides a framework +for developing and deploying device Root of Trust services in FF-A [2] S-EL0 +Secure Partitions. The project hosts the reference implementation of the Arm +Platform Security Architecture [3] for Arm A-profile devices. + +The FF-A Secure Partitions (SP) are accessible through the FF-A driver [4] which +provides the low level communication for this driver. On top of that the Trusted +Services RPC protocol is used [5]. To use the driver from user space a reference +implementation is provided at [6], which is part of the Trusted Services client +library called libts [7]. + +All Trusted Services (TS) SPs have the same FF-A UUID, it identifies the TS RPC +protocol. A TS SP can host one or more services (e.g. PSA Crypto, PSA ITS, etc). +A service is identified by its service UUID, the same type of service cannot be +present twice in the same SP. During SP boot each service in the SP is assigned +an "interface ID", this is just a short ID to simplify message addressing. + +The generic TEE design is to share memory at once with the TEE implementation, +which can then be reused to communicate with multiple TAs. However, in case of +FF-A, memory sharing works on an endpoint level, i.e. memory is shared with a +specific SP. User space has to be able to separately share memory with each SP +based on its endpoint ID, therefore a separate TEE device is registered for each +discovered TS SP. Opening the SP corresponds to opening the TEE device and +creating a TEE context. A TS SP hosts one or more services, opening a service +corresponds to opening a session in the given tee_context. + +Overview of a system with Trusted Services components:: + + User space Kernel space Secure world + ~~~~~~~~~~ ~~~~~~~~~~~~ ~~~~~~~~~~~~ + +--------+ +-------------+ + | Client | | Trusted | + +--------+ | Services SP | + /\ +-------------+ + || /\ + || || + || || + / / + +-------+ +----------+--------+ +-------------+ + | libts | | TEE | TS-TEE | | FF-A SPMC | + | | | subsys | driver | | + SPMD | + +-------+----------------+----+-----+--------+-----------+-------------+ + | Generic TEE API | | FF-A | TS RPC protocol | + | IOCTL (TEE_IOC_*) | | driver | over FF-A | + +-----------------------------+ +--------+-------------------------+ + +References +========== + +[1] https://www.trustedfirmware.org/projects/trusted-services/ + +[2] https://developer.arm.com/documentation/den0077/ + +[3] https://www.arm.com/architecture/security-features/platform-security + +[4] drivers/firmware/arm_ffa/ + +[5] https://trusted-services.readthedocs.io/en/v1.0.0/developer/service-access-p... + +[6] https://git.trustedfirmware.org/TS/trusted-services.git/tree/components/rpc/... + +[7] https://git.trustedfirmware.org/TS/trusted-services.git/tree/deployments/lib...