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-rw-r--r--Documentation/userspace-api/index.rst1
-rw-r--r--Documentation/userspace-api/tee.rst39
2 files changed, 40 insertions, 0 deletions
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.