Re: [PATCH] Documentation: tee: Document TEE kernel interface

[Maxim Uvarov]

Hello Sumit,

if this doc is for driver developers it might be useful to add some
code examples how to register drivers on tee bus.

Best regards,
Maxim.

On Wed, 3 Jun 2020 at 14:31, Sumit Garg <sumit.garg@xxxxxxxxxx> wrote:
>
> Update documentation with TEE bus infrastructure which provides an
> interface for kernel client drivers to communicate with corresponding
> Trusted Application.
>
> Signed-off-by: Sumit Garg <sumit.garg@xxxxxxxxxx>
> ---
>  Documentation/tee.txt | 30 ++++++++++++++++++++++++++++++
>  1 file changed, 30 insertions(+)
>
> diff --git a/Documentation/tee.txt b/Documentation/tee.txt
> index c8fad81..428d3b5 100644
> --- a/Documentation/tee.txt
> +++ b/Documentation/tee.txt
> @@ -53,6 +53,28 @@ clients, forward them to the TEE and send back the results. In the case of
>  supplicants the communication goes in the other direction, the TEE sends
>  requests to the supplicant which then sends back the result.
>
> +The TEE kernel interface
> +========================
> +
> +Kernel provides a TEE bus infrastructure where a Trusted Application is
> +represented as a device identified via Universally Unique Identifier (UUID) and
> +client drivers register a table of supported device UUIDs.
> +
> +TEE bus infrastructure registers following APIs:
> +-  match(): iterates over the client driver UUID table to find a corresponding
> +   match for device UUID. If a match is found, then this particular device is
> +   probed via corresponding probe API registered by the client driver. This
> +   process happens whenever a device or a client driver is registered with TEE
> +   bus.
> +-  uevent(): notifies user-space (udev) whenever a new device is registered on
> +   TEE bus for auto-loading of modularized client drivers.
> +
> +TEE bus device enumeration is specific to underlying TEE implementation, so it
> +is left open for TEE drivers to provide corresponding implementation.
> +
> +Then TEE client driver can talk to a matched Trusted Application using APIs
> +listed in include/linux/tee_drv.h.
> +
>  OP-TEE driver
>  =============
>
> @@ -112,6 +134,14 @@ kernel are handled by the kernel driver. Other RPC messages will be forwarded to
>  tee-supplicant without further involvement of the driver, except switching
>  shared memory buffer representation.
>
> +OP-TEE device enumeration
> +-------------------------
> +
> +OP-TEE provides a pseudo Trusted Application: drivers/tee/optee/device.c in
> +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.
> +
>  AMD-TEE driver
>  ==============
>
> --
> 2.7.4
>