On Sun, Jul 13, 2025 at 05:49:24PM -0700, Amirreza Zarrabi wrote: > Add documentation for the Qualcomm TEE driver. > > Signed-off-by: Amirreza Zarrabi <amirreza.zarr...@oss.qualcomm.com> > --- > Documentation/tee/index.rst | 1 + > Documentation/tee/qtee.rst | 96 > +++++++++++++++++++++++++++++++++++++++++++++ > MAINTAINERS | 1 + > 3 files changed, 98 insertions(+)
Acked-by: Sumit Garg <sumit.g...@oss.qualcomm.com> -Sumit > > diff --git a/Documentation/tee/index.rst b/Documentation/tee/index.rst > index 4be6e69d7837..62afb7ee9b52 100644 > --- a/Documentation/tee/index.rst > +++ b/Documentation/tee/index.rst > @@ -11,6 +11,7 @@ TEE Subsystem > op-tee > amd-tee > ts-tee > + qtee > > .. only:: subproject and html > > diff --git a/Documentation/tee/qtee.rst b/Documentation/tee/qtee.rst > new file mode 100644 > index 000000000000..2fa2c1bf6384 > --- /dev/null > +++ b/Documentation/tee/qtee.rst > @@ -0,0 +1,96 @@ > +.. SPDX-License-Identifier: GPL-2.0 > + > +============================================= > +QTEE (Qualcomm Trusted Execution Environment) > +============================================= > + > +The QTEE driver handles communication with Qualcomm TEE [1]. > + > +The lowest level of communication with QTEE builds on the ARM SMC Calling > +Convention (SMCCC) [2], which is the foundation for QTEE's Secure Channel > +Manager (SCM) [3] used internally by the driver. > + > +In a QTEE-based system, services are represented as objects with a series of > +operations that can be called to produce results, including other objects. > + > +When an object is hosted within QTEE, executing its operations is referred > +to as "direct invocation". QTEE can also invoke objects hosted in the > non-secure > +world using a method known as "callback request". > + > +The SCM provides two functions to support direct invocation and callback > requests: > + > +- QCOM_SCM_SMCINVOKE_INVOKE: Used for direct invocation. It can return either > + a result or initiate a callback request. > +- QCOM_SCM_SMCINVOKE_CB_RSP: Used to submit a response to a callback request > + triggered by a previous direct invocation. > + > +The QTEE Transport Message [4] is stacked on top of the SCM driver functions. > + > +A message consists of two buffers shared with QTEE: inbound and outbound > +buffers. The inbound buffer is used for direct invocation, and the outbound > +buffer is used to make callback requests. This picture shows the contents of > +a QTEE transport message:: > + > + +---------------------+ > + | v > + +-----------------+-------+-------+------+--------------------------+ > + | qcomtee_msg_ |object | buffer | | > + | object_invoke | id | offset, size | | > (inbound buffer) > + +-----------------+-------+--------------+--------------------------+ > + <---- header -----><---- arguments ------><- in/out buffer payload -> > + > + +-----------+ > + | v > + +-----------------+-------+-------+------+----------------------+ > + | qcomtee_msg_ |object | buffer | | > + | callback | id | offset, size | | > (outbound buffer) > + +-----------------+-------+--------------+----------------------+ > + > +Each buffer is started with a header and array of arguments. > + > +QTEE Transport Message supports four types of arguments: > + > +- Input Object (IO) is an object parameter to the current invocation > + or callback request. > +- Output Object (OO) is an object parameter from the current invocation > + or callback request. > +- Input Buffer (IB) is (offset, size) pair to the inbound or outbound region > + to store parameter to the current invocation or callback request. > +- Output Buffer (OB) is (offset, size) pair to the inbound or outbound region > + to store parameter from the current invocation or callback request. > + > +Picture of the relationship between the different components in the QTEE > +architecture:: > + > + User space Kernel Secure world > + ~~~~~~~~~~ ~~~~~~ ~~~~~~~~~~~~ > + +--------+ +----------+ +--------------+ > + | Client | |callback | | Trusted | > + +--------+ |server | | Application | > + /\ +----------+ +--------------+ > + || +----------+ /\ /\ > + || |callback | || || > + || |server | || \/ > + || +----------+ || +--------------+ > + || /\ || | TEE Internal | > + || || || | API | > + \/ \/ \/ +--------+--------+ +--------------+ > + +---------------------+ | TEE | QTEE | | QTEE | > + | libqcomtee [5] | | subsys | driver | | Trusted OS | > + +-------+-------------+--+----+-------+----+-------------+--------------+ > + | Generic TEE API | | QTEE MSG | > + | IOCTL (TEE_IOC_*) | | SMCCC (QCOM_SCM_SMCINVOKE_*) | > + +-----------------------------+ +---------------------------------+ > + > +References > +========== > + > +[1] > https://docs.qualcomm.com/bundle/publicresource/topics/80-70015-11/qualcomm-trusted-execution-environment.html > + > +[2] http://infocenter.arm.com/help/topic/com.arm.doc.den0028a/index.html > + > +[3] drivers/firmware/qcom/qcom_scm.c > + > +[4] drivers/tee/qcomtee/qcomtee_msg.h > + > +[5] https://github.com/quic/quic-teec > diff --git a/MAINTAINERS b/MAINTAINERS > index 9fc58f48fa14..391fc6e6defc 100644 > --- a/MAINTAINERS > +++ b/MAINTAINERS > @@ -20706,6 +20706,7 @@ QUALCOMM TEE (QCOMTEE) DRIVER > M: Amirreza Zarrabi <amirreza.zarr...@oss.qualcomm.com> > L: linux-arm-...@vger.kernel.org > S: Maintained > +F: Documentation/tee/qtee.rst > F: drivers/tee/qcomtee/ > > QUALCOMM TRUST ZONE MEMORY ALLOCATOR > > -- > 2.34.1 >
