Hi Jens, On 23 August 2018 at 04:43, Jens Wiklander <[email protected]> wrote: > Signed-off-by: Jens Wiklander <[email protected]> > --- > doc/README.tee | 112 +++++++++++++++++++++++++++++++++++++++++++++++++ > 1 file changed, 112 insertions(+) > create mode 100644 doc/README.tee
Reviewed-by: Simon Glass <[email protected]> Looks good, nits below. > > diff --git a/doc/README.tee b/doc/README.tee > new file mode 100644 > index 000000000000..e9c9ef67877a > --- /dev/null > +++ b/doc/README.tee > @@ -0,0 +1,112 @@ > +============= > +TEE uclass > +============= > + > +This document describes the TEE uclass in U-boot U-Boot (please can you check all your patches for that? There are more below) > + > +A TEE (Trusted Execution Environment) is a trusted OS running in some > +secure environment, for example, TrustZone on ARM CPUs, or a separate > +secure co-processor etc. A TEE driver handles the details needed to > +communicate with the TEE. > + > +This uclass deals with: > + > +- Registration of TEE drivers > + > +- Managing shared memory between U-boot and the TEE > + > +- Providing a generic API to the TEE > + > +The TEE interface > +================= > + > +include/tee.h defines the generic interface to a TEE. > + > +A client finds the TEE device via tee_find_device(). Other important > functions > +when interfacing with a TEE are: > + > +- tee_shm_alloc(), tee_shm_register() and tee_shm_free() to manage shared > + memory objects often needed when communicating with the TEE. > + > +- tee_get_version() lets the client know which the capabilities of the TEE > + device. > + > +- tee_open_session() opens a session to a Trusted Application > + > +- tee_invoke_func() invokes a function in a Trusted Application > + > +- tee_close_session() closes a session to a Trusted Application > + > +Much of the communication between clients and the TEE is opaque to the > +driver. The main job for the driver is to receive requests from the > +clients, forward them to the TEE and send back the results. > + > +OP-TEE driver > +============= > + > +The OP-TEE driver handles OP-TEE [1] based TEEs. Currently it is only the ARM > +TrustZone based OP-TEE solution that is supported. In fact, wouldn't other things be supported by different drivers? Perhaps you should name your driver to indicate it is only for ARM? > + > +Lowest level of communication with OP-TEE builds on ARM SMC Calling > +Convention (SMCCC) [2], which is the foundation for OP-TEE's SMC interface > +[3] used internally by the driver. Stacked on top of that is OP-TEE Message > +Protocol [4]. > + > +OP-TEE SMC interface provides the basic functions required by SMCCC and some > +additional functions specific for OP-TEE. The most interesting functions are: > + > +- OPTEE_SMC_FUNCID_CALLS_UID (part of SMCCC) returns the version information > + which is then returned by TEE_IOC_VERSION > + > +- OPTEE_SMC_CALL_GET_OS_UUID returns the particular OP-TEE implementation, > used > + to tell, for instance, a TrustZone OP-TEE apart from an OP-TEE running on a > + separate secure co-processor. > + > +- OPTEE_SMC_CALL_WITH_ARG drives the OP-TEE message protocol > + > +- OPTEE_SMC_GET_SHM_CONFIG lets the driver and OP-TEE agree on which memory > + range to used for shared memory between Linux and OP-TEE. > + > +The GlobalPlatform TEE Client API [5] is implemented on top of the generic > +TEE API. > + > +Picture of the relationship between the different components in the > +OP-TEE architecture: > + > + U-boot Secure world > + ~~~~~~ ~~~~~~~~~~~~ > + +------------+ +-------------+ > + | Client | | Trusted | > + | | | Application | > + +------------+ +-------------+ > + /\ /\ > + || || > + \/ \/ > + +------------+ +-------------+ > + | TEE | | TEE Internal| > + | uclass | | API | > + +------------+ +-------------+ > + | OP-TEE | | OP-TEE | > + | driver | | Trusted OS | > + +------------+-----------+-------------+ > + | OP-TEE MSG | > + | SMCCC (OPTEE_SMC_CALL_*) | > + +--------------------------------------+ > + > +RPC (Remote Procedure Call) are requests from secure world to the driver. > +An RPC is identified by a special range of SMCCC return values from > +OPTEE_SMC_CALL_WITH_ARG. > + > +References > +========== > + > +[1] https://github.com/OP-TEE/optee_os > + > +[2] http://infocenter.arm.com/help/topic/com.arm.doc.den0028a/index.html > + > +[3] drivers/tee/optee/optee_smc.h > + > +[4] drivers/tee/optee/optee_msg.h > + > +[5] http://www.globalplatform.org/specificationsdevice.asp look for > + "TEE Client API Specification v1.0" and click download. > -- > 2.17.1 > Regards, Simon _______________________________________________ U-Boot mailing list [email protected] https://lists.denx.de/listinfo/u-boot
