From: Sumit Garg <redacted>

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 <redacted>
---
 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;