Hi Sumit, On 5/22/2026 9:59 PM, Sumit Garg 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. > > Reviewed-by: Mukesh Ojha <[email protected]> > Tested-by: Mukesh Ojha <[email protected]> # Lemans > Reviewed-by: Harshal Dev <[email protected]> > Tested-by: Vignesh Viswanathan <[email protected]> # > IPQ9650 > Signed-off-by: Sumit Garg <[email protected]> > --- > drivers/firmware/qcom/Kconfig | 8 + > drivers/firmware/qcom/Makefile | 1 + > drivers/firmware/qcom/qcom_pas.c | 291 +++++++++++++++++++++++++ > drivers/firmware/qcom/qcom_pas.h | 50 +++++ > include/linux/firmware/qcom/qcom_pas.h | 43 ++++ > 5 files changed, 393 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..9f66cc774508 100644 > --- a/drivers/firmware/qcom/Kconfig > +++ b/drivers/firmware/qcom/Kconfig > @@ -6,6 +6,14 @@ > > menu "Qualcomm firmware drivers" > > +config QCOM_PAS > + tristate "Qualcomm generic PAS interface driver" > + 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..bc6c42f2b3c6 > --- /dev/null > +++ b/drivers/firmware/qcom/qcom_pas.c > @@ -0,0 +1,291 @@ > +// SPDX-License-Identifier: GPL-2.0 > +/* > + * Copyright (c) 2010,2015,2019 The Linux Foundation. All rights reserved. > + * Copyright (C) 2015 Linaro Ltd. > + * 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" > + > +static struct qcom_pas_ops *ops_ptr; > + > +/** > + * devm_qcom_pas_context_alloc() - Allocate peripheral authentication service > + * context for a given peripheral > + * > + * PAS context is device-resource managed, so the caller does not need > + * to worry about freeing the context memory. > + * > + * @dev: PAS firmware device > + * @pas_id: peripheral authentication service id > + * @mem_phys: Subsystem reserve memory start address > + * @mem_size: Subsystem reserve memory size > + * > + * Return: The new PAS context, or ERR_PTR() on failure. > + */ > +struct qcom_pas_context *devm_qcom_pas_context_alloc(struct device *dev, > + u32 pas_id, > + phys_addr_t mem_phys, > + size_t mem_size) > +{ > + struct qcom_pas_context *ctx; > + > + ctx = devm_kzalloc(dev, sizeof(*ctx), GFP_KERNEL); > + if (!ctx) > + return ERR_PTR(-ENOMEM); > + > + ctx->dev = dev; > + ctx->pas_id = pas_id; > + ctx->mem_phys = mem_phys; > + ctx->mem_size = mem_size; > + > + return ctx; > +} > +EXPORT_SYMBOL_GPL(devm_qcom_pas_context_alloc); > + > +/** > + * qcom_pas_init_image() - Initialize peripheral authentication service state > + * machine for a given peripheral, using the metadata > + * @pas_id: peripheral authentication service id > + * @metadata: pointer to memory containing ELF header, program header > table > + * and optional blob of data used for authenticating the metadata > + * and the rest of the firmware > + * @size: size of the metadata > + * @ctx: optional pas context > + * > + * Return: 0 on success. > + * > + * Upon successful return, the PAS metadata context (@ctx) will be used to > + * track the metadata allocation, this needs to be released by invoking > + * qcom_pas_metadata_release() by the caller. > + */ > +int qcom_pas_init_image(u32 pas_id, const void *metadata, size_t size, > + struct qcom_pas_context *ctx) > +{ > + if (!ops_ptr) > + return -ENODEV; > + > + return ops_ptr->init_image(ops_ptr->dev, pas_id, metadata, size, ctx); > +} > +EXPORT_SYMBOL_GPL(qcom_pas_init_image); > + > +/** > + * qcom_pas_metadata_release() - release metadata context > + * @ctx: pas context > + */ > +void qcom_pas_metadata_release(struct qcom_pas_context *ctx) > +{ > + if (!ops_ptr || !ctx || !ctx->ptr) > + return; > + > + ops_ptr->metadata_release(ops_ptr->dev, ctx); > +} > +EXPORT_SYMBOL_GPL(qcom_pas_metadata_release); > + > +/** > + * qcom_pas_mem_setup() - Prepare the memory related to a given peripheral > + * for firmware loading > + * @pas_id: peripheral authentication service id > + * @addr: start address of memory area to prepare > + * @size: size of the memory area to prepare > + * > + * Return: 0 on success. > + */ > +int qcom_pas_mem_setup(u32 pas_id, phys_addr_t addr, phys_addr_t size) > +{ > + if (!ops_ptr) > + return -ENODEV; > + > + return ops_ptr->mem_setup(ops_ptr->dev, pas_id, addr, size); > +} > +EXPORT_SYMBOL_GPL(qcom_pas_mem_setup); > + > +/** > + * qcom_pas_get_rsc_table() - Retrieve the resource table in passed output > buffer > + * for a given peripheral. > + * > + * Qualcomm remote processor may rely on both static and dynamic resources > for > + * its functionality. Static resources typically refer to memory-mapped > + * addresses required by the subsystem and are often embedded within the > + * firmware binary and dynamic resources, such as shared memory in DDR etc., > + * are determined at runtime during the boot process. > + * > + * On Qualcomm Technologies devices, it's possible that static resources are > + * not embedded in the firmware binary and instead are provided by TrustZone. > + * However, dynamic resources are always expected to come from TrustZone. > This > + * indicates that for Qualcomm devices, all resources (static and dynamic) > will > + * be provided by TrustZone PAS service. > + * > + * If the remote processor firmware binary does contain static resources, > they > + * should be passed in input_rt. These will be forwarded to TrustZone for > + * authentication. TrustZone will then append the dynamic resources and > return > + * the complete resource table in output_rt_tzm. > + * > + * If the remote processor firmware binary does not include a resource table, > + * the caller of this function should set input_rt as NULL and input_rt_size > + * as zero respectively. > + * > + * More about documentation on resource table data structures can be found in > + * include/linux/remoteproc.h > + * > + * @ctx: PAS context > + * @pas_id: peripheral authentication service id > + * @input_rt: resource table buffer which is present in firmware binary > + * @input_rt_size: size of the resource table present in firmware binary > + * @output_rt_size: TrustZone expects caller should pass worst case size for > + * the output_rt_tzm. > + * > + * Return: > + * On success, returns a pointer to the allocated buffer containing the > final > + * resource table and output_rt_size will have actual resource table size > from > + * TrustZone. The caller is responsible for freeing the buffer. On failure, > + * returns ERR_PTR(-errno). > + */ > +struct resource_table *qcom_pas_get_rsc_table(struct qcom_pas_context *ctx, > + void *input_rt, > + size_t input_rt_size, > + size_t *output_rt_size) > +{ > + if (!ops_ptr) > + return ERR_PTR(-ENODEV); > + if (!ctx) > + return ERR_PTR(-EINVAL); > + > + return ops_ptr->get_rsc_table(ops_ptr->dev, ctx, input_rt, > + input_rt_size, output_rt_size); > +} > +EXPORT_SYMBOL_GPL(qcom_pas_get_rsc_table); > + > +/** > + * qcom_pas_auth_and_reset() - Authenticate the given peripheral firmware > + * and reset the remote processor > + * @pas_id: peripheral authentication service id > + * > + * Return: 0 on success. > + */ > +int qcom_pas_auth_and_reset(u32 pas_id) > +{ > + if (!ops_ptr) > + return -ENODEV; > + > + return ops_ptr->auth_and_reset(ops_ptr->dev, pas_id); > +} > +EXPORT_SYMBOL_GPL(qcom_pas_auth_and_reset); > + > +/** > + * qcom_pas_prepare_and_auth_reset() - Prepare, authenticate, and reset the > + * remote processor > + * > + * @ctx: Context saved during call to devm_qcom_pas_context_alloc() > + * > + * This function performs the necessary steps to prepare a PAS subsystem, > + * authenticate it using the provided metadata, and initiate a reset > sequence. > + * > + * It should be used when Linux is in control setting up the IOMMU hardware > + * for remote subsystem during secure firmware loading processes. The > + * preparation step sets up a shmbridge over the firmware memory before > + * TrustZone accesses the firmware memory region for authentication. The > + * authentication step verifies the integrity and authenticity of the > firmware > + * or configuration using secure metadata. Finally, the reset step ensures > the > + * subsystem starts in a clean and sane state. > + * > + * Return: 0 on success, negative errno on failure. > + */ > +int qcom_pas_prepare_and_auth_reset(struct qcom_pas_context *ctx) > +{ > + if (!ops_ptr) > + return -ENODEV; > + if (!ctx) > + return -EINVAL; > + > + return ops_ptr->prepare_and_auth_reset(ops_ptr->dev, ctx); > +} > +EXPORT_SYMBOL_GPL(qcom_pas_prepare_and_auth_reset); > + > +/** > + * qcom_pas_set_remote_state() - Set the remote processor state > + * @state: peripheral state > + * @pas_id: peripheral authentication service id > + * > + * Return: 0 on success. > + */ > +int qcom_pas_set_remote_state(u32 state, u32 pas_id) > +{ > + if (!ops_ptr) > + return -ENODEV; > + > + return ops_ptr->set_remote_state(ops_ptr->dev, state, pas_id); > +} > +EXPORT_SYMBOL_GPL(qcom_pas_set_remote_state); > + > +/** > + * qcom_pas_shutdown() - Shut down the remote processor > + * @pas_id: peripheral authentication service id > + * > + * Return: 0 on success. > + */ > +int qcom_pas_shutdown(u32 pas_id) > +{ > + if (!ops_ptr) > + return -ENODEV; > + > + return ops_ptr->shutdown(ops_ptr->dev, pas_id); > +} > +EXPORT_SYMBOL_GPL(qcom_pas_shutdown); > + > +/** > + * qcom_pas_supported() - Check if the peripheral authentication service is > + * available for the given peripheral > + * @pas_id: peripheral authentication service id > + * > + * Return: true if PAS is supported for this peripheral, otherwise false. > + */ > +bool qcom_pas_supported(u32 pas_id) > +{ > + if (!ops_ptr) > + return false; > + > + return ops_ptr->supported(ops_ptr->dev, pas_id); > +} > +EXPORT_SYMBOL_GPL(qcom_pas_supported); > + > +bool qcom_pas_is_available(void) > +{ > + /* > + * The barrier for ops_ptr is intended to synchronize the data stores > + * for the ops data structure when client drivers are in parallel > + * checking for PAS service availability. > + * > + * Once the PAS backend becomes available, it is allowed for multiple > + * threads to enter TZ for parallel bringup of co-processors during > + * boot. > + */ > + return !!smp_load_acquire(&ops_ptr); > +} > +EXPORT_SYMBOL_GPL(qcom_pas_is_available); > + > +void qcom_pas_ops_register(struct qcom_pas_ops *ops) > +{ > + if (!qcom_pas_is_available()) > + /* Paired with smp_load_acquire() in qcom_pas_is_available() */ > + smp_store_release(&ops_ptr, ops); > + else > + pr_err("qcom_pas: ops already registered by %s\n", > + ops_ptr->drv_name); > +} > +EXPORT_SYMBOL_GPL(qcom_pas_ops_register); > + > +void qcom_pas_ops_unregister(void) > +{ > + /* Paired with smp_load_acquire() in qcom_pas_is_available() */ > + smp_store_release(&ops_ptr, NULL); > +} > +EXPORT_SYMBOL_GPL(qcom_pas_ops_unregister); > + > +MODULE_LICENSE("GPL"); > +MODULE_DESCRIPTION("Qualcomm generic TZ PAS driver"); > diff --git a/drivers/firmware/qcom/qcom_pas.h > b/drivers/firmware/qcom/qcom_pas.h > new file mode 100644 > index 000000000000..8643e2760602 > --- /dev/null > +++ b/drivers/firmware/qcom/qcom_pas.h > @@ -0,0 +1,50 @@ > +/* SPDX-License-Identifier: GPL-2.0 */ > +/* > + * Copyright (c) Qualcomm Technologies, Inc. and/or its subsidiaries. > + */ > + > +#ifndef __QCOM_PAS_INT_H > +#define __QCOM_PAS_INT_H > + > +struct device; > + > +/** > + * struct qcom_pas_ops - Qcom Peripheral Authentication Service (PAS) ops > + * @drv_name: PAS driver name. > + * @dev: PAS device pointer. > + * @supported: Peripheral supported callback. > + * @init_image: Peripheral image initialization > callback. > + * @mem_setup: Peripheral memory setup callback. > + * @get_rsc_table: Peripheral get resource table callback. > + * @prepare_and_auth_reset: Peripheral prepare firmware authentication and > + * reset callback. > + * @auth_and_reset: Peripheral firmware authentication and reset > + * callback. > + * @set_remote_state: Peripheral set remote state callback. > + * @shutdown: Peripheral shutdown callback. > + * @metadata_release: Image metadata release callback. > + */ > +struct qcom_pas_ops { > + const char *drv_name; > + struct device *dev; > + bool (*supported)(struct device *dev, u32 pas_id); > + int (*init_image)(struct device *dev, u32 pas_id, const void *metadata, > + size_t size, struct qcom_pas_context *ctx); > + int (*mem_setup)(struct device *dev, u32 pas_id, phys_addr_t addr, > + phys_addr_t size); > + void *(*get_rsc_table)(struct device *dev, struct qcom_pas_context *ctx, > + void *input_rt, size_t input_rt_size, > + size_t *output_rt_size); > + int (*prepare_and_auth_reset)(struct device *dev, > + struct qcom_pas_context *ctx); > + int (*auth_and_reset)(struct device *dev, u32 pas_id); > + int (*set_remote_state)(struct device *dev, u32 state, u32 pas_id); > + int (*shutdown)(struct device *dev, u32 pas_id); > + void (*metadata_release)(struct device *dev, > + struct qcom_pas_context *ctx); > +}; > + > +void qcom_pas_ops_register(struct qcom_pas_ops *ops); > +void qcom_pas_ops_unregister(void); > + > +#endif /* __QCOM_PAS_INT_H */ > diff --git a/include/linux/firmware/qcom/qcom_pas.h > b/include/linux/firmware/qcom/qcom_pas.h > new file mode 100644 > index 000000000000..65b1c9564458 > --- /dev/null > +++ b/include/linux/firmware/qcom/qcom_pas.h > @@ -0,0 +1,43 @@ > +/* SPDX-License-Identifier: GPL-2.0-only */ > +/* > + * Copyright (c) 2010-2015, 2018-2019 The Linux Foundation. All rights > reserved. > + * Copyright (C) 2015 Linaro Ltd. > + * Copyright (c) Qualcomm Technologies, Inc. and/or its subsidiaries. > + */ > + > +#ifndef __QCOM_PAS_H > +#define __QCOM_PAS_H > + > +#include <linux/err.h> > +#include <linux/types.h> > + > +struct qcom_pas_context { > + struct device *dev; > + u32 pas_id; > + phys_addr_t mem_phys; > + size_t mem_size; > + void *ptr; > + dma_addr_t phys; > + ssize_t size; > + bool use_tzmem; > +}; > + > +bool qcom_pas_is_available(void); > +struct qcom_pas_context *devm_qcom_pas_context_alloc(struct device *dev, > + u32 pas_id, > + phys_addr_t mem_phys, > + size_t mem_size); > +int qcom_pas_init_image(u32 pas_id, const void *metadata, size_t size, > + struct qcom_pas_context *ctx); > +struct resource_table *qcom_pas_get_rsc_table(struct qcom_pas_context *ctx, > + void *input_rt, size_t > input_rt_size, > + size_t *output_rt_size); > +int qcom_pas_mem_setup(u32 pas_id, phys_addr_t addr, phys_addr_t size); > +int qcom_pas_auth_and_reset(u32 pas_id); > +int qcom_pas_prepare_and_auth_reset(struct qcom_pas_context *ctx); > +int qcom_pas_set_remote_state(u32 state, u32 pas_id); > +int qcom_pas_shutdown(u32 pas_id); > +bool qcom_pas_supported(u32 pas_id); > +void qcom_pas_metadata_release(struct qcom_pas_context *ctx); > + > +#endif /* __QCOM_PAS_H */
I have a question about the shape of the generic PAS abstraction. Looking at the current interface, it seems that pas_id is still treated as the primary identity for most PAS operations, while struct qcom_pas_context is used as optional extended state for the operations that need it. I can see how this maps well to the existing SCM PAS interface and keeps the transition simple. However, I wonder if this makes the abstraction less generic in the long term. Some callbacks in struct qcom_pas_ops receive only pas_id, while others receive struct qcom_pas_context *ctx. This works as long as pas_id is sufficient for those operations. But if a backend needs per-peripheral private state for operations such as auth_and_reset, shutdown, or set_remote_state, it would need to reconstruct that state from pas_id or maintain a separate pas_id to backend-context mapping. Would it be cleaner to make struct qcom_pas_context the common per-peripheral object and pass it consistently to all per-peripheral callbacks? Existing backends could still use ctx->pas_id, but future backends would not need to perform a separate lookup only because the callback was passed a raw pas_id. I also wonder whether struct qcom_pas_context is exposing some implementation-specific state. Fields such as ptr, phys, size, and use_tzmem seem to describe how the current SCM/QTEE implementations manage metadata memory, rather than generic PAS state. For another backend, the per-operation state might be a tee_shm, an FF-A memory handle, shared or lent memory state, or something else transport-specific. Would it make sense to keep only the common PAS fields in struct qcom_pas_context, such as dev, pas_id, and possibly the firmware memory address/size if those are truly generic, and add a backend-private pointer for implementation-specific state? I may be missing a reason why the pas_id-only callbacks are preferred, but if this is intended to be the long-term generic PAS layer rather than mainly a shim over the existing SCM API shape, using the context consistently and keeping backend-specific state private seems easier to extend. Regards, Amir
