Subject: Re: [PATCH v3 00/15] firmware: qcom: Add OP-TEE PAS service support

From: Bjorn Andersson <[email-masked]>
Date: Mon, 6 Apr 2026 10:09:27 -0500

On Fri, Mar 27, 2026 at 06:40:28PM +0530, Sumit Garg wrote:
> From: Sumit Garg <[email-masked]>
> 
> Qcom platforms has the legacy of using non-standard SCM calls
> splintered over the various kernel drivers. These SCM calls aren't
> compliant with the standard SMC calling conventions which is a
> prerequisite to enable migration to the FF-A specifications from Arm.
> 

Please get our colleagues involved in this discussion, because this
non-SCM interface does not match the direction we are taking.

Regards,
Bjorn

> OP-TEE as an alternative trusted OS to Qualcomm TEE (QTEE) can't
> support these non-standard SCM calls. And even for newer architectures
> using S-EL2 with Hafnium support, QTEE won't be able to support SCM
> calls either with FF-A requirements coming in. And with both OP-TEE
> and QTEE drivers well integrated in the TEE subsystem, it makes further
> sense to reuse the TEE bus client drivers infrastructure.
> 
> The added benefit of TEE bus infrastructure is that there is support
> for discoverable/enumerable services. With that client drivers don't
> have to manually invoke a special SCM call to know the service status.
> 
> So enable the generic Peripheral Authentication Service (PAS) provided
> by the firmware. It acts as the common layer with different TZ
> backends plugged in whether it's an SCM implementation or a proper
> TEE bus based PAS service implementation.
> 
> The TEE PAS service ABI is designed to be extensible with additional API
> as PTA_QCOM_PAS_CAPABILITIES. This allows to accommodate any future
> extensions of the PAS service needed while still maintaining backwards
> compatibility.
> 
> Currently OP-TEE support is being added to provide the backend PAS
> service implementation which can be found as part of this PR [1].
> This implementation has been tested on Kodiak/RB3Gen2 board with lemans
> EVK board being the next target. In addition to that WIN/IPQ targets
> planning to use OP-TEE will use this service too. Surely the backwards
> compatibility is maintained and tested for SCM backend.
> 
> Patch summary:
> - Patch #1: adds Kodiak EL2 overlay since boot stack with TF-A/OP-TEE
>   only allow UEFI and Linux to boot in EL2.
> - Patch #2: adds generic PAS service.
> - Patch #3: migrates SCM backend to generic PAS service.
> - Patch #4: adds TEE/OP-TEE backend for generic PAS service.
> - Patch #5-#13: migrates all client drivers to generic PAS service.
> - Patch #14: drops legacy PAS SCM exported APIs.
> 
> The patch-set is based on v7.0-rc5 tag and can be found in git tree here
> [2].
> 
> Merge strategy:
> 
> It is expected due to APIs dependency, the entire patch-set to go via
> the Qcom tree. All other subsystem maintainers, it will be great if I
> can get acks for the corresponding subsystem patches.
> 
> [1] https://github.com/OP-TEE/optee_os/pull/7721
> [2] https://git.kernel.org/pub/scm/linux/kernel/git/sumit.garg/linux.git/log/?h=qcom-pas-v3
> 
> ---
> Changes in v3:
> - Incorporated some style and misc. comments for patch #2, #3 and #4.
> - Add QCOM_PAS Kconfig dependency for various subsystems.
> - Switch from pseudo TA to proper TA invoke commands.
> 
> Changes in v2:
> - Fixed kernel doc warnings.
> - Polish commit message and comments for patch #2.
> - Pass proper PAS ID in set_remote_state API for media firmware drivers.
> - Added Maintainer entry and dropped MODULE_AUTHOR.
> 
> Mukesh Ojha (1):
>   arm64: dts: qcom: kodiak: Add EL2 overlay
> 
> Sumit Garg (14):
>   firmware: qcom: Add a generic PAS service
>   firmware: qcom_scm: Migrate to generic PAS service
>   firmware: qcom: Add a PAS TEE service
>   remoteproc: qcom_q6v5_pas: Switch over to generic PAS TZ APIs
>   remoteproc: qcom_q6v5_mss: Switch to generic PAS TZ APIs
>   soc: qcom: mdtloader: Switch to generic PAS TZ APIs
>   remoteproc: qcom_wcnss: Switch to generic PAS TZ APIs
>   remoteproc: qcom: Select QCOM_PAS generic service
>   drm/msm: Switch to generic PAS TZ APIs
>   media: qcom: Switch to generic PAS TZ APIs
>   net: ipa: Switch to generic PAS TZ APIs
>   wifi: ath12k: Switch to generic PAS TZ APIs
>   firmware: qcom_scm: Remove SCM PAS wrappers
>   MAINTAINERS: Add maintainer entry for Qualcomm PAS TZ service
> 
>  MAINTAINERS                                   |   9 +
>  arch/arm64/boot/dts/qcom/Makefile             |   2 +
>  arch/arm64/boot/dts/qcom/kodiak-el2.dtso      |  35 ++
>  drivers/firmware/qcom/Kconfig                 |  19 +
>  drivers/firmware/qcom/Makefile                |   2 +
>  drivers/firmware/qcom/qcom_pas.c              | 288 +++++++++++
>  drivers/firmware/qcom/qcom_pas.h              |  50 ++
>  drivers/firmware/qcom/qcom_pas_tee.c          | 478 ++++++++++++++++++
>  drivers/firmware/qcom/qcom_scm.c              | 302 ++++-------
>  drivers/gpu/drm/msm/Kconfig                   |   1 +
>  drivers/gpu/drm/msm/adreno/a5xx_gpu.c         |   4 +-
>  drivers/gpu/drm/msm/adreno/adreno_gpu.c       |  11 +-
>  drivers/media/platform/qcom/iris/Kconfig      |  25 +-
>  .../media/platform/qcom/iris/iris_firmware.c  |   9 +-
>  drivers/media/platform/qcom/venus/Kconfig     |   1 +
>  drivers/media/platform/qcom/venus/firmware.c  |  11 +-
>  drivers/net/ipa/Kconfig                       |   2 +-
>  drivers/net/ipa/ipa_main.c                    |  13 +-
>  drivers/net/wireless/ath/ath12k/Kconfig       |   2 +-
>  drivers/net/wireless/ath/ath12k/ahb.c         |   8 +-
>  drivers/remoteproc/Kconfig                    |   1 +
>  drivers/remoteproc/qcom_q6v5_mss.c            |   5 +-
>  drivers/remoteproc/qcom_q6v5_pas.c            |  51 +-
>  drivers/remoteproc/qcom_wcnss.c               |  12 +-
>  drivers/soc/qcom/mdt_loader.c                 |  12 +-
>  include/linux/firmware/qcom/qcom_pas.h        |  43 ++
>  include/linux/firmware/qcom/qcom_scm.h        |  29 --
>  include/linux/soc/qcom/mdt_loader.h           |   6 +-
>  28 files changed, 1114 insertions(+), 317 deletions(-)
>  create mode 100644 arch/arm64/boot/dts/qcom/kodiak-el2.dtso
>  create mode 100644 drivers/firmware/qcom/qcom_pas.c
>  create mode 100644 drivers/firmware/qcom/qcom_pas.h
>  create mode 100644 drivers/firmware/qcom/qcom_pas_tee.c
>  create mode 100644 include/linux/firmware/qcom/qcom_pas.h
> 
> -- 
> 2.51.0
>