Looks good for me.
Reviewed-by: Maxim Uvarov <maxim.uvarov@xxxxxxxxxx>
On Thu, 4 Jun 2020 at 10:00, 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>
> ---
>
> Changes in v2:
> - Add TEE client driver example snippet.
>
> Documentation/tee.txt | 68 +++++++++++++++++++++++++++++++++++++++++++++++++++
> 1 file changed, 68 insertions(+)
>
> diff --git a/Documentation/tee.txt b/Documentation/tee.txt
> index c8fad81..350dd40 100644
> --- a/Documentation/tee.txt
> +++ b/Documentation/tee.txt
> @@ -53,6 +53,66 @@ 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.
> +
> +TEE client driver example
> +-------------------------
> +
> +Suppose a TEE client driver needs to communicate with a Trusted Application
> +having UUID: ``ac6a4085-0e82-4c33-bf98-8eb8e118b6c2``, so driver registration
> +snippet would look like::
> +
> + static const struct tee_client_device_id client_id_table[] = {
> + {UUID_INIT(0xac6a4085, 0x0e82, 0x4c33,
> + 0xbf, 0x98, 0x8e, 0xb8, 0xe1, 0x18, 0xb6, 0xc2)},
> + {}
> + };
> +
> + MODULE_DEVICE_TABLE(tee, client_id_table);
> +
> + static struct tee_client_driver client_driver = {
> + .id_table = client_id_table,
> + .driver = {
> + .name = DRIVER_NAME,
> + .bus = &tee_bus_type,
> + .probe = client_probe,
> + .remove = client_remove,
> + },
> + };
> +
> + static int __init client_init(void)
> + {
> + return driver_register(&client_driver.driver);
> + }
> +
> + static void __exit client_exit(void)
> + {
> + driver_unregister(&client_driver.driver);
> + }
> +
> + module_init(client_init);
> + module_exit(client_exit);
> +
> OP-TEE driver
> =============
>
> @@ -112,6 +172,14 @@ 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
>
