Commit 63d5bc42 authored by Jens Wiklander's avatar Jens Wiklander
Browse files

docs: staging/tee.rst: add a section on OP-TEE notifications 



Adds a section on notifications used by OP-TEE, synchronous and
asynchronous.

Reviewed-by: default avatarSumit Garg <sumit.garg@linaro.org>
Acked-by: default avatarMarc Zyngier <maz@kernel.org>
Signed-off-by: default avatarJens Wiklander <jens.wiklander@linaro.org>
parent fa55b7dc

Documentation/staging/tee.rst

+30 −0
Original line number Diff line number Diff line
@@ -184,6 +184,36 @@ order to support device enumeration. In other words, OP-TEE driver invokes this 
application to retrieve a list of Trusted Applications which can be registered

as devices on the TEE bus.



OP-TEE notifications

--------------------



There are two kinds of notifications that secure world can use to make

normal world aware of some event.



1. Synchronous notifications delivered with ``OPTEE_RPC_CMD_NOTIFICATION``

   using the ``OPTEE_RPC_NOTIFICATION_SEND`` parameter.

2. Asynchronous notifications delivered with a combination of a non-secure

   edge-triggered interrupt and a fast call from the non-secure interrupt

   handler.



Synchronous notifications are limited by depending on RPC for delivery,

this is only usable when secure world is entered with a yielding call via

``OPTEE_SMC_CALL_WITH_ARG``. This excludes such notifications from secure

world interrupt handlers.



An asynchronous notification is delivered via a non-secure edge-triggered

interrupt to an interrupt handler registered in the OP-TEE driver. The

actual notification value are retrieved with the fast call

``OPTEE_SMC_GET_ASYNC_NOTIF_VALUE``. Note that one interrupt can represent

multiple notifications.



One notification value ``OPTEE_SMC_ASYNC_NOTIF_VALUE_DO_BOTTOM_HALF`` has a

special meaning. When this value is received it means that normal world is

supposed to make a yielding call ``OPTEE_MSG_CMD_DO_BOTTOM_HALF``. This

call is done from the thread assisting the interrupt handler. This is a

building block for OP-TEE OS in secure world to implement the top half and

bottom half style of device drivers.



AMD-TEE driver

==============