This patchset allows OP-TEE to communicate with I2C devices; a typical use case would be servicing U-Boot requests that require underlying cryptographic operations implemented by an I2C chip.
On a board fitted with the NXP SE050 I2C secure element, OP-TEE can route some of the cryptographic operations it needs to that device (ie RSA, ECC, CTR..).
Before the REE executes, OP-TEE would use its own I2C drivers to communicate with the device on the bus; later on, once the REE is up, accesses to the I2C bus should be coordinated with the REE to avoid collisions. However instead of implementing such a synchronization mechanism, this trampoline service permits OP-TEE to route those I2C requests back to U-boot without then having to worry about collisions.
Lets suppose that U-Boot executes the trusted application Android Verified Boot; when OP-TEE receives the request - and before executing the application - it uses RSA to verify it. So on the back of the TA function invocation, OP-TEE returns to U-boot with a sequence of RPC calls requesting I2C transfers (check carefully the implementation in do_call_with_arg(...) implemented in drivers/tee/optee/core.c and notice the while loop)
When using sandbox testing, RPC is called directly to validate its actual implementation; however as succintly described above, these calls will always be originated in OP-TEE.
Igor Opaniuk (3): test: py: add pygit2 and pyelftools to requirements.txt drivers: tee: sandbox: add rpc test ta emulation test: dm: tee: extend with RPC test
Jorge Ramirez-Ortiz (1): drivers: tee: i2c trampoline driver
drivers/tee/Makefile | 2 + drivers/tee/optee/Kconfig | 9 ++ drivers/tee/optee/Makefile | 1 + drivers/tee/optee/i2c.c | 90 +++++++++++++++ drivers/tee/optee/optee_msg.h | 21 ++++ drivers/tee/optee/optee_msg_supplicant.h | 5 + drivers/tee/optee/optee_private.h | 17 +++ drivers/tee/optee/supplicant.c | 3 + drivers/tee/sandbox.c | 137 ++++++++++++++++++++++- include/tee/optee_ta_rpc_test.h | 28 +++++ test/dm/tee.c | 109 +++++++++++++++++- test/py/requirements.txt | 2 + 12 files changed, 415 insertions(+), 9 deletions(-) create mode 100644 drivers/tee/optee/i2c.c create mode 100644 include/tee/optee_ta_rpc_test.h