Hi Simon, On Wed, Aug 29, 2018 at 06:28:54PM -0600, Simon Glass wrote: > Hi Jens, > > On 23 August 2018 at 04:43, Jens Wiklander <jens.wiklan...@linaro.org> wrote: > > Signed-off-by: Jens Wiklander <jens.wiklan...@linaro.org> > > --- > > doc/README.tee | 112 +++++++++++++++++++++++++++++++++++++++++++++++++ > > 1 file changed, 112 insertions(+) > > create mode 100644 doc/README.tee > > Reviewed-by: Simon Glass <s...@chromium.org> > > 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)
Yes, I'll check them all. > > > + > > +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? The OP-TEE Message prototol isn't tied to ARM only and OP-TEE has been or is used on at least one other architecture (not open sourced though). I think that only small changes will be needed in the the OP-TEE driver to support a different architecture as long as shared memory still can be used. I'd rather keep the name as just "optee" until we know what we need to adapt to. > > > + > > +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 > > Thanks for the review, Jens _______________________________________________ U-Boot mailing list U-Boot@lists.denx.de https://lists.denx.de/listinfo/u-boot
