From 50709576d81bbcbe027d22c64cd2ec934bd9087b Mon Sep 17 00:00:00 2001 From: Sumit Garg Date: Tue, 28 Nov 2023 12:53:52 +0530 Subject: 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: Rijo Thomas Acked-by: Jens Wiklander Signed-off-by: Sumit Garg Signed-off-by: Jonathan Corbet Link: https://lore.kernel.org/r/20231128072352.866859-1-sumit.garg@linaro.org --- Documentation/userspace-api/index.rst | 1 + Documentation/userspace-api/tee.rst | 39 +++++++++++++++++++++++++++++++++++ 2 files changed, 40 insertions(+) create mode 100644 Documentation/userspace-api/tee.rst (limited to 'Documentation/userspace-api') diff --git a/Documentation/userspace-api/index.rst b/Documentation/userspace-api/index.rst index bf8d2ee01580..93174ffc7350 100644 --- a/Documentation/userspace-api/index.rst +++ b/Documentation/userspace-api/index.rst @@ -30,6 +30,7 @@ place where this information is gathered. sysfs-platform_profile vduse futex2 + tee .. only:: subproject and html diff --git a/Documentation/userspace-api/tee.rst b/Documentation/userspace-api/tee.rst new file mode 100644 index 000000000000..e2368dbc3451 --- /dev/null +++ b/Documentation/userspace-api/tee.rst @@ -0,0 +1,39 @@ +.. SPDX-License-Identifier: GPL-2.0 +.. tee: + +================================================== +TEE (Trusted Execution Environment) Userspace API +================================================== + +include/uapi/linux/tee.h defines the generic interface to a TEE. + +User space (the client) connects to the driver by opening /dev/tee[0-9]* or +/dev/teepriv[0-9]*. + +- TEE_IOC_SHM_ALLOC allocates shared memory and returns a file descriptor + which user space can mmap. When user space doesn't need the file + descriptor any more, it should be closed. When shared memory isn't needed + any longer it should be unmapped with munmap() to allow the reuse of + memory. + +- TEE_IOC_VERSION lets user space know which TEE this driver handles and + its capabilities. + +- TEE_IOC_OPEN_SESSION opens a new session to a Trusted Application. + +- TEE_IOC_INVOKE invokes a function in a Trusted Application. + +- TEE_IOC_CANCEL may cancel an ongoing TEE_IOC_OPEN_SESSION or TEE_IOC_INVOKE. + +- TEE_IOC_CLOSE_SESSION closes a session to a Trusted Application. + +There are two classes of clients, normal clients and supplicants. The latter is +a helper process for the TEE to access resources in Linux, for example file +system access. A normal client opens /dev/tee[0-9]* and a supplicant opens +/dev/teepriv[0-9]. + +Much of the communication between clients and the TEE is opaque to the +driver. The main job for the driver is to receive requests from the +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. -- cgit v1.2.3