Re: [PATCH v2 02/15] firmware: qcom: Add a generic PAS service

[Trilok Soni]

On 3/16/2026 12:51 AM, Krzysztof Kozlowski wrote:
> On 12/03/2026 07:27, Sumit Garg wrote:
>> From: Sumit Garg <sumit.garg@xxxxxxxxxxxxxxxx>
>>
>> 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
>> with S-EL2 and 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 <sumit.garg@xxxxxxxxxxxxxxxx>
>> ---
>>  drivers/firmware/qcom/Kconfig          |   8 +
>>  drivers/firmware/qcom/Makefile         |   1 +
>>  drivers/firmware/qcom/qcom_pas.c       | 298 +++++++++++++++++++++++++
>>  drivers/firmware/qcom/qcom_pas.h       |  53 +++++
>>  include/linux/firmware/qcom/qcom_pas.h |  41 ++++
>>  5 files changed, 401 insertions(+)
>>  create mode 100644 drivers/firmware/qcom/qcom_pas.c
>>  create mode 100644 drivers/firmware/qcom/qcom_pas.h
>>  create mode 100644 include/linux/firmware/qcom/qcom_pas.h
>>
>> diff --git a/drivers/firmware/qcom/Kconfig b/drivers/firmware/qcom/Kconfig
>> index b477d54b495a..8653639d06db 100644
>> --- a/drivers/firmware/qcom/Kconfig
>> +++ b/drivers/firmware/qcom/Kconfig
>> @@ -6,6 +6,14 @@
>>  
>>  menu "Qualcomm firmware drivers"
>>  
>> +config QCOM_PAS
>> +	tristate
>> +	help
>> +	  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.
>> +
>>  config QCOM_SCM
>>  	select QCOM_TZMEM
>>  	tristate
>> diff --git a/drivers/firmware/qcom/Makefile b/drivers/firmware/qcom/Makefile
>> index 0be40a1abc13..dc5ab45f906a 100644
>> --- a/drivers/firmware/qcom/Makefile
>> +++ b/drivers/firmware/qcom/Makefile
>> @@ -8,3 +8,4 @@ qcom-scm-objs += qcom_scm.o qcom_scm-smc.o qcom_scm-legacy.o
>>  obj-$(CONFIG_QCOM_TZMEM)	+= qcom_tzmem.o
>>  obj-$(CONFIG_QCOM_QSEECOM)	+= qcom_qseecom.o
>>  obj-$(CONFIG_QCOM_QSEECOM_UEFISECAPP) += qcom_qseecom_uefisecapp.o
>> +obj-$(CONFIG_QCOM_PAS)		+= qcom_pas.o
>> diff --git a/drivers/firmware/qcom/qcom_pas.c b/drivers/firmware/qcom/qcom_pas.c
>> new file mode 100644
>> index 000000000000..beb1bae55546
>> --- /dev/null
>> +++ b/drivers/firmware/qcom/qcom_pas.c
>> @@ -0,0 +1,298 @@
>> +// SPDX-License-Identifier: GPL-2.0
>> +/*
>> + * Copyright (c) Qualcomm Technologies, Inc. and/or its subsidiaries.
>> + */
>> +
>> +#include <linux/device/devres.h>
>> +#include <linux/firmware/qcom/qcom_pas.h>
>> +#include <linux/kernel.h>
>> +#include <linux/module.h>
>> +
>> +#include "qcom_pas.h"
>> +
>> +struct qcom_pas_ops *ops_ptr;
> 
> Same comment as before. Don't create singletons. And for sure not global
> ones.

I agree, no globals here please. 

> 
> Best regards,
> Krzysztof