Re: [PATCH v4 02/15] firmware: qcom: Add a generic PAS service

On 4/27/2026 3:25 PM, Sumit Garg via OP-TEE wrote:
> From: Sumit Garg <[email protected]>
> 
> 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.
> 
> 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.
> 
> Signed-off-by: Sumit Garg <[email protected]>
> ---

Reviewed-by: Harshal Dev <[email protected]>

Regards,
Harshal