Commit 50709576 authored by Sumit Garg's avatar Sumit Garg Committed by Jonathan Corbet
Browse files

Documentation: Destage TEE subsystem documentation 



Add a separate documentation directory for TEE subsystem since it is a
standalone subsystem which already offers devices consumed by multiple
different subsystem drivers.

Split overall TEE subsystem documentation modularly where:
- The userspace API has been moved to Documentation/userspace-api/tee.rst.
- The driver API has been moved to Documentation/driver-api/tee.rst.
- The first module covers the overview of TEE subsystem.
- The further modules are dedicated to different TEE implementations like:
  - OP-TEE
  - AMD-TEE
  - and so on for future TEE implementation support.

Acked-by: default avatarRijo Thomas <Rijo-john.Thomas@amd.com>
Acked-by: default avatarJens Wiklander <jens.wiklander@linaro.org>
Signed-off-by: default avatarSumit Garg <sumit.garg@linaro.org>
Signed-off-by: default avatarJonathan Corbet <corbet@lwn.net>
Link: https://lore.kernel.org/r/20231128072352.866859-1-sumit.garg@linaro.org
parent e57ddc6c

Documentation/driver-api/index.rst

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@@ -112,6 +112,7 @@ available subsections can be seen below. 
   hte/index

   wmi

   dpll

   tee



.. only::  subproject and html

Documentation/driver-api/tee.rst

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.. SPDX-License-Identifier: GPL-2.0



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

TEE (Trusted Execution Environment) driver API

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



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);

Documentation/security/keys/trusted-encrypted.rst

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@@ -88,7 +88,7 @@ safe. 
     (2) TEE



         TEEs have well-documented, standardized client interface and APIs. For

         more details refer to ``Documentation/staging/tee.rst``.

         more details refer to ``Documentation/driver-api/tee.rst``.



     (3) CAAM

Documentation/staging/index.rst

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@@ -12,5 +12,4 @@ Unsorted Documentation 
   rpmsg

   speculation

   static-keys

   tee

   xz

Documentation/subsystem-apis.rst

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@@ -86,3 +86,4 @@ Storage interfaces 
   misc-devices/index

   peci/index

   wmi/index

   tee/index