Re: [PATCH v19 2/6] remoteproc: Add TEE support

Harshal Dev
2025-07-31T10:26:00Z

Hello Arnaud,

On 6/25/2025 3:10 PM, Arnaud Pouliquen wrote:
> Add a remoteproc TEE (Trusted Execution Environment) driver that will be
> probed by the TEE bus. If the associated Trusted application is supported
> on the secure part, this driver offers a client interface to load firmware
> by the secure part.
> This firmware could be authenticated by the secure trusted application.
>
> A specificity of the implementation is that the firmware has to be
> authenticated and optionally decrypted to access the resource table.
>
> Consequently, the boot sequence is:
>
> 1) rproc_parse_fw --> rproc_tee_parse_fw
> remoteproc TEE:
> - Requests the TEE application to authenticate and load the firmware
> in the remote processor memories.
> - Requests the TEE application for the address of the resource table.
> - Creates a copy of the resource table stored in rproc->cached_table.
>
> 2) rproc_load_segments --> rproc_tee_load_fw
> remoteproc TEE:
> - Requests the TEE application to load the firmware. Nothing is done
> at the TEE application as the firmware is already loaded.
> - In case of recovery, the TEE application has to reload the firmware.
>
> 3) rproc_tee_get_loaded_rsc_table
> remoteproc TEE requests the TEE application for the address of the
> resource table.
>
> 4) rproc_start --> rproc_tee_start
> - Requests the TEE application to start the remote processor.
>
> The shutdown sequence is:
>
> 5) rproc_stop --> rproc_tee_stop
> - Requests the TEE application to stop the remote processor.
>
> 6) rproc_tee_release_fw
> This function is used to request the TEE application to perform actions
> to return to the initial state on stop or on error during the boot
> sequence.
>
> Signed-off-by: Arnaud Pouliquen <arnaud.pouliquen@foss.st.com>
> ---
> Updates vs version [18]:
> - rework/fix function headers
> - use memremap instead of ioremap for the resource table.
> - realign comments to 80 chars limit, with few exceptions for readability
> - replace spinlock by mutex and and protect APIs from concurrent access
> - add support of 64-bit address in rproc_tee_get_loaded_rsc_table()
> - Generalize teston rproc_tee_ctx.dev to prevent an unbind
> - update copyright year
>
> Updates vs version [17]:
> Fix warning:
> warning: EXPORT_SYMBOL() is used, but #include <linux/export.h> is missing
> ---
> drivers/remoteproc/Kconfig | 10 +
> drivers/remoteproc/Makefile | 1 +
> drivers/remoteproc/remoteproc_tee.c | 708 ++++++++++++++++++++++++++++
> include/linux/remoteproc_tee.h | 87 ++++
> 4 files changed, 806 insertions(+)
> create mode 100644 drivers/remoteproc/remoteproc_tee.c
> create mode 100644 include/linux/remoteproc_tee.h
>
> diff --git a/drivers/remoteproc/Kconfig b/drivers/remoteproc/Kconfig
> index 83962a114dc9..e39265d249d9 100644
> --- a/drivers/remoteproc/Kconfig
> +++ b/drivers/remoteproc/Kconfig
> @@ -23,6 +23,16 @@ config REMOTEPROC_CDEV
>
> It's safe to say N if you don't want to use this interface.
>
> +config REMOTEPROC_TEE
> + bool "Remoteproc support by a TEE application"
> + depends on OPTEE
> + help
> + Support a remote processor that is managed by an application running in a Trusted
> + Execution Environment (TEE). This application is responsible for loading the remote
> + processor firmware image and managing its lifecycle.
> +
> + It's safe to say N if the remote processor is not managed by a TEE.
> +
> config IMX_REMOTEPROC
> tristate "i.MX remoteproc support"
> depends on ARCH_MXC
> diff --git a/drivers/remoteproc/Makefile b/drivers/remoteproc/Makefile
> index 1c7598b8475d..a1a5201982d4 100644
> --- a/drivers/remoteproc/Makefile
> +++ b/drivers/remoteproc/Makefile
> @@ -11,6 +11,7 @@ remoteproc-y += remoteproc_sysfs.o
> remoteproc-y += remoteproc_virtio.o
> remoteproc-y += remoteproc_elf_loader.o
> obj-$(CONFIG_REMOTEPROC_CDEV) += remoteproc_cdev.o
> +obj-$(CONFIG_REMOTEPROC_TEE) += remoteproc_tee.o
> obj-$(CONFIG_IMX_REMOTEPROC) += imx_rproc.o
> obj-$(CONFIG_IMX_DSP_REMOTEPROC) += imx_dsp_rproc.o
> obj-$(CONFIG_INGENIC_VPU_RPROC) += ingenic_rproc.o
> diff --git a/drivers/remoteproc/remoteproc_tee.c b/drivers/remoteproc/remoteproc_tee.c
> new file mode 100644
> index 000000000000..b9da911b8a83
> --- /dev/null
> +++ b/drivers/remoteproc/remoteproc_tee.c
> @@ -0,0 +1,708 @@
> +// SPDX-License-Identifier: GPL-2.0-or-later
> +/*
> + * Copyright (C) STMicroelectronics 2025
> + * Author: Arnaud Pouliquen <arnaud.pouliquen@foss.st.com>
> + */
> +
> +#include <linux/export.h>
> +#include <linux/firmware.h>
> +#include <linux/io.h>
> +#include <linux/module.h>
> +#include <linux/platform_device.h>
> +#include <linux/remoteproc.h>
> +#include <linux/remoteproc_tee.h>
> +#include <linux/slab.h>
> +#include <linux/tee_drv.h>
> +
> +#define MAX_TEE_PARAM_ARRAY_MEMBER 4
> +
> +/*
> + * Authentication and load of the firmware image in the remote processor
> + * memories by the TEE. After this step the firmware is installed in destination
> + * memories, which can then be locked to prevent access by Linux.
> + *
> + * [in] params[0].value.a: remote processor identifier
> + * [in] params[1].memref: buffer containing a temporary copy of the signed
> + * image to load.
> + */
> +#define TA_RPROC_FW_CMD_LOAD_FW 1
> +
> +/*
> + * Start the remote processor by the TEE
> + *
> + * [in] params[0].value.a: remote processor identifier
> + */
> +#define TA_RPROC_FW_CMD_START 2
> +
> +/*
> + * Stop the remote processor by the TEE
> + *
> + * [in] params[0].value.a: remote processor identifier
> + */
> +#define TA_RPROC_FW_CMD_STOP 3
> +
> +/*
> + * Return the address of the resource table, or 0 if not found.
> + *
> + * [in] params[0].value.a: remote processor identifier
> + * [out] params[1].value.a: 32bit LSB resource table memory address
> + * [out] params[1].value.b: 32bit MSB resource table memory address
> + * [out] params[2].value.a: 32bit LSB resource table memory size
> + * [out] params[2].value.b: 32bit MSB resource table memory size
> + */
> +#define TA_RPROC_FW_CMD_GET_RSC_TABLE 4
> +
> +/*
> + * Release remote processor firmware images and associated resources.
> + * This command should be used in case an error occurs between the loading of
> + * the firmware images (TA_RPROC_CMD_LOAD_FW) and the starting of the remote
> + * processor (TA_RPROC_CMD_START_FW) or after stopping the remote processor
> + * to release associated resources (TA_RPROC_CMD_STOP_FW).
> + *
> + * [in] params[0].value.a: remote processor identifier
> + */
> +#define TA_RPROC_CMD_RELEASE_FW 6
> +
> +struct rproc_tee_context {
> + struct list_head sessions;
> + struct tee_context *tee_ctx;
> + struct device *dev;
> +};
> +
> +/**
> + * struct rproc_tee - TEE remoteproc structure
> + * @node: Reference in list
> + * @rproc: Remoteproc reference
> + * @rproc_id: remote processor identifier
> + * @session_id: TEE session identifier
> + */
> +struct rproc_tee {
> + struct list_head node;
> + struct rproc *rproc;
> + u32 rproc_id;
> + u32 session_id;
> +};
> +
> +static struct rproc_tee_context rproc_tee_ctx;
> +static struct mutex (ctx_lock); /* Protects concurrent manipulations of the rproc_tee_ctx*/
> +

Since ctx_lock is protecting struct rproc_tee_ctx, can we place it within the struct?

> +static struct rproc_tee *rproc_to_trproc(struct rproc *rproc)
> +{
> + struct rproc_tee *trproc;
> +
> + list_for_each_entry(trproc, &rproc_tee_ctx.sessions, node)
> + if (trproc->rproc == rproc)
> + return trproc;
> +
> + return NULL;
> +}
> +
> +static void rproc_tee_prepare_args(struct rproc_tee *trproc, int cmd,
> + struct tee_ioctl_invoke_arg *arg,
> + struct tee_param *param,
> + unsigned int num_params)
> +{
> + memset(arg, 0, sizeof(*arg));
> + memset(param, 0, MAX_TEE_PARAM_ARRAY_MEMBER * sizeof(*param));
> +
> + arg->func = cmd;
> + arg->session = trproc->session_id;
> + arg->num_params = num_params + 1;
> +
> + param[0] = (struct tee_param) {
> + .attr = TEE_IOCTL_PARAM_ATTR_TYPE_VALUE_INPUT,
> + .u.value.a = trproc->rproc_id,
> + };
> +}
> +
> +/**
> + * rproc_tee_release_fw() - Release the firmware for a TEE-based remote processor
> + * @rproc: Pointer to the struct rproc representing the remote processor
> + *
> + * This function invokes the TA_RPROC_CMD_RELEASE_FW TEE client function to
> + * release the firmware. It should only be called when the remoteproc state is
> + * RPROC_OFFLINE or RPROC_DETACHED. The function requests the TEE remoteproc
> + * application to release the firmware loaded by rproc_tee_load_fw().
> + * The request is ignored if the rproc state is RPROC_DETACHED as the remote
> + * processor is still running.
> + */
> +void rproc_tee_release_fw(struct rproc *rproc)
> +{
> + struct tee_param param[MAX_TEE_PARAM_ARRAY_MEMBER];
> + struct rproc_tee *trproc;
> + struct tee_ioctl_invoke_arg arg;
> + int ret;
> +
> + ret = mutex_lock_interruptible(&ctx_lock);
> + if (ret)
> + return;
> +
> + if (!rproc_tee_ctx.dev)
> + goto out;
> +
> + trproc = rproc_to_trproc(rproc);
> + if (!trproc)
> + goto out;
> +
> + /*
> + * If the remote processor state is RPROC_DETACHED, just ignore the
> + * request, as the remote processor is still running.
> + */
> + if (rproc->state == RPROC_DETACHED)
> + goto out;
> +
> + if (rproc->state != RPROC_OFFLINE) {
> + dev_err(rproc_tee_ctx.dev, "unexpected rproc state: %d\n", rproc->state);
> + goto out;
> + }
> +
> + rproc_tee_prepare_args(trproc, TA_RPROC_CMD_RELEASE_FW, &arg, param, 0);
> +
> + ret = tee_client_invoke_func(rproc_tee_ctx.tee_ctx, &arg, param);
> + if (ret < 0 || arg.ret != 0) {
> + dev_err(rproc_tee_ctx.dev,
> + "TA_RPROC_CMD_RELEASE_FW invoke failed TEE err: %#x, ret:%d\n",
> + arg.ret, ret);
> + }
> +
> +out:
> + mutex_unlock(&ctx_lock);
> +}
> +EXPORT_SYMBOL_GPL(rproc_tee_release_fw);
> +
> +/**
> + * rproc_tee_load_fw() - Load firmware from TEE application
> + * @rproc: Pointer to the struct rproc representing the remote processor
> + * @fw: Pointer to the firmware structure containing the firmware data and size
> + *
> + * This function invokes the TA_RPROC_FW_CMD_LOAD_FW TEE client function to load
> + * the firmware. It registers the fw->data as a shared memory region with the
> + * TEE, and request the TEE to load the firmware. This function can be called
> + * twice during the remote processor boot, a first by rproc_tee_parse_fw() to
> + * parse the resource table , and a second time by rproc_tee_load_fw().
> + * The TEE application should ignores the command if the firmware
> + * is already loaded by rproc_tee_parse_fw().
> + *
> + * Return: 0 on success, or an error code on failure
> + */
> +int rproc_tee_load_fw(struct rproc *rproc, const struct firmware *fw)
> +{
> + struct tee_param param[MAX_TEE_PARAM_ARRAY_MEMBER];
> + struct rproc_tee *trproc;
> + struct tee_ioctl_invoke_arg arg;
> + struct tee_shm *fw_shm;
> + int ret;
> +
> + ret = mutex_lock_interruptible(&ctx_lock);
> + if (ret)
> + return ret;
> +
> + if (!rproc_tee_ctx.dev) {
> + ret = -ENODEV;
> + goto out;
> + }
> +
> + trproc = rproc_to_trproc(rproc);
> + if (!trproc) {
> + ret = -EINVAL;
> + goto out;
> + }
> +
> + fw_shm = tee_shm_register_kernel_buf(rproc_tee_ctx.tee_ctx, (void *)fw->data, fw->size);
> + if (IS_ERR(fw_shm)) {
> + ret = PTR_ERR(fw_shm);
> + goto out;
> + }
> +
> + rproc_tee_prepare_args(trproc, TA_RPROC_FW_CMD_LOAD_FW, &arg, param, 1);
> +
> + /* Provide the address of the firmware image */
> + param[1] = (struct tee_param) {
> + .attr = TEE_IOCTL_PARAM_ATTR_TYPE_MEMREF_INPUT,
> + .u.memref = {
> + .shm = fw_shm,
> + .size = fw->size,
> + .shm_offs = 0,
> + },
> + };
> +
> + ret = tee_client_invoke_func(rproc_tee_ctx.tee_ctx, &arg, param);
> + if (ret < 0 || arg.ret != 0) {
> + dev_err(rproc_tee_ctx.dev,
> + "TA_RPROC_FW_CMD_LOAD_FW invoke failed TEE err: %#x, ret:%d\n",
> + arg.ret, ret);
> + if (!ret)
> + ret = -EIO;
> + }
> +
> + tee_shm_free(fw_shm);
> +
> +out:
> + mutex_unlock(&ctx_lock);
> + return ret;
> +}
> +EXPORT_SYMBOL_GPL(rproc_tee_load_fw);
> +
> +static int rproc_tee_get_loaded_rsc_table(struct rproc *rproc, phys_addr_t *rsc_pa,
> + size_t *table_sz)
> +{
> + struct tee_param param[MAX_TEE_PARAM_ARRAY_MEMBER];
> + struct rproc_tee *trproc;
> + struct tee_ioctl_invoke_arg arg;
> + int ret;
> +
> + ret = mutex_lock_interruptible(&ctx_lock);
> + if (ret)
> + return ret;
> +
> + if (!rproc_tee_ctx.dev) {
> + ret = -ENODEV;
> + goto out;
> + }
> +
> + trproc = rproc_to_trproc(rproc);
> + if (!trproc) {
> + ret = -EINVAL;
> + goto out;
> + }
> +
> + rproc_tee_prepare_args(trproc, TA_RPROC_FW_CMD_GET_RSC_TABLE, &arg, param, 2);
> +
> + param[1].attr = TEE_IOCTL_PARAM_ATTR_TYPE_VALUE_OUTPUT;
> + param[2].attr = TEE_IOCTL_PARAM_ATTR_TYPE_VALUE_OUTPUT;
> +
> + ret = tee_client_invoke_func(rproc_tee_ctx.tee_ctx, &arg, param);
> + if (ret < 0 || arg.ret != 0) {
> + dev_err(rproc_tee_ctx.dev,
> + "TA_RPROC_FW_CMD_GET_RSC_TABLE invoke failed TEE err: %#x, ret:%d\n",
> + arg.ret, ret);
> + ret = -EIO;
> + goto out;
> + }
> +
> + *table_sz = param[2].u.value.a;
> + if (sizeof(phys_addr_t) == sizeof(u64))
> + *table_sz |= param[2].u.value.b << 32;
> +
> + if (*table_sz) {
> + *rsc_pa = param[1].u.value.a;
> + if (sizeof(phys_addr_t) == sizeof(u64))
> + *rsc_pa |= param[1].u.value.b << 32;
> + } else {
> + *rsc_pa = 0;
> + }
> +
> +out:
> + mutex_unlock(&ctx_lock);
> + return ret;
> +}
> +
> +/**
> + * rproc_tee_parse_fw() - Get the resource table from TEE application
> + * @rproc: Pointer to the struct rproc representing the remote processor
> + * @fw: Pointer to the firmware structure containing the firmware data and size
> + *
> + * This function retrieves the loaded resource table and creates a cached_table
> + * copy. Since the firmware image is signed and potentially encrypted, the
> + * firmware must be loaded first to access the loaded resource table.
> + *
> + * Return: 0 on success, or an error code on failure
> + */
> +int rproc_tee_parse_fw(struct rproc *rproc, const struct firmware *fw)
> +{
> + phys_addr_t rsc_table;
> + void *rsc_va;
> + size_t table_sz;
> + int ret;
> +
> + if (!rproc)
> + return -EINVAL;
> +
> + /* We need first to Load the firmware, to be able to get the resource table. */
> + ret = rproc_tee_load_fw(rproc, fw);
> + if (ret)
> + return ret;
> +
> + ret = rproc_tee_get_loaded_rsc_table(rproc, &rsc_table, &table_sz);
> + if (ret)
> + goto release_fw;
> +
> + /*
> + * We assume here that the memory mapping is the same between the TEE
> + * and Linux kernel contexts. Else a new TEE remoteproc service could be
> + * needed to get a copy of the resource table.
> + */
> + rsc_va = memremap(rsc_table, table_sz, MEMREMAP_WC);
> + if (!rsc_va) {
> + dev_err(rproc_tee_ctx.dev, "Unable to map memory region: %pa+%zx\n",
> + &rsc_table, table_sz);
> + ret = -ENOMEM;
> + goto release_fw;
> + }
> +
> + /*
> + * Create a copy of the resource table to have the same behavior as the
> + * ELF loader. This cached table will be used by the remoteproc core
> + * after the remoteproc stops to free resources and for crash recovery
> + * to reapply the settings.
> + * The cached table will be freed by the remoteproc core.
> + */
> + rproc->cached_table = kmemdup(rsc_va, table_sz, GFP_KERNEL);
> + memunmap(rsc_va);
> +
> + if (!rproc->cached_table) {
> + ret = -ENOMEM;
> + goto release_fw;
> + }
> +
> + rproc->table_ptr = rproc->cached_table;
> + rproc->table_sz = table_sz;
> +
> + return 0;
> +
> +release_fw:
> + rproc_tee_release_fw(rproc);
> + return ret;
> +}
> +EXPORT_SYMBOL_GPL(rproc_tee_parse_fw);
> +
> +/**
> + * rproc_tee_find_loaded_rsc_table() - Find the loaded resource table loaded by
> + * the TEE application
> + * @rproc: Pointer to the struct rproc representing the remote processor
> + * @fw: Pointer to the firmware structure containing the firmware data and size
> + *
> + * This function retrieves the physical address and size of the resource table
> + * loaded by the TEE application.
> + *
> + * Return: pointer to the resource table if found, or NULL if not found or size
> + * is 0
> + */
> +struct resource_table *rproc_tee_find_loaded_rsc_table(struct rproc *rproc,
> + const struct firmware *fw)
> +{
> + phys_addr_t rsc_table;
> + size_t table_sz;
> + int ret;
> +
> + ret = rproc_tee_get_loaded_rsc_table(rproc, &rsc_table, &table_sz);
> + if (ret)
> + return NULL;
> +
> + rproc->table_sz = table_sz;
> + if (!table_sz)
> + return NULL;
> +
> + /*
> + * At this step the memory area that contains the resource table should
> + * have been registered by the remote proc platform driver and allocated
> + * by rproc_alloc_registered_carveouts().
> + */
> + return rproc_pa_to_va(rproc, rsc_table, table_sz, NULL);
> +}
> +EXPORT_SYMBOL_GPL(rproc_tee_find_loaded_rsc_table);
> +
> +/**
> + * rproc_tee_start() - Request the TEE application to start the remote processor
> + * @rproc: Pointer to the struct rproc representing the remote processor
> + *
> + * This function invokes the TA_RPROC_FW_CMD_START command to start the remote
> + * processor.
> + *
> + * Return: Returns 0 on success, -EINVAL or -EIO on failure
> + */
> +int rproc_tee_start(struct rproc *rproc)
> +{
> + struct tee_param param[MAX_TEE_PARAM_ARRAY_MEMBER];
> + struct rproc_tee *trproc;
> + struct tee_ioctl_invoke_arg arg;
> + int ret;
> +
> + ret = mutex_lock_interruptible(&ctx_lock);
> + if (ret)
> + return ret;
> +
> + if (!rproc_tee_ctx.dev) {
> + ret = -ENODEV;
> + goto out;
> + }
> +
> + trproc = rproc_to_trproc(rproc);
> + if (!trproc) {
> + ret = -EINVAL;
> + goto out;
> + }
> +
> + rproc_tee_prepare_args(trproc, TA_RPROC_FW_CMD_START, &arg, param, 0);
> +
> + ret = tee_client_invoke_func(rproc_tee_ctx.tee_ctx, &arg, param);
> + if (ret < 0 || arg.ret != 0) {
> + dev_err(rproc_tee_ctx.dev,
> + "TA_RPROC_FW_CMD_START invoke failed TEE err: %#x, ret:%d\n", arg.ret, ret);
> + if (!ret)
> + ret = -EIO;
> + }
> +
> +out:
> + mutex_unlock(&ctx_lock);
> + return ret;
> +}
> +EXPORT_SYMBOL_GPL(rproc_tee_start);
> +
> +/**
> + * rproc_tee_stop() - Request the TEE application to start the remote processor
> + * @rproc: Pointer to the struct rproc representing the remote processor
> + *
> + * This function invokes the TA_RPROC_FW_CMD_STOP command to stop the remote
> + * processor.
> + *
> + * Return: Returns 0 on success, -EINVAL or -EIO on failure
> + */
> +int rproc_tee_stop(struct rproc *rproc)
> +{
> + struct tee_param param[MAX_TEE_PARAM_ARRAY_MEMBER];
> + struct rproc_tee *trproc;
> + struct tee_ioctl_invoke_arg arg;
> + int ret;
> +
> + ret = mutex_lock_interruptible(&ctx_lock);
> + if (ret)
> + return ret;
> +
> + if (!rproc_tee_ctx.dev) {
> + ret = -ENODEV;
> + goto out;
> + }
> +
> + trproc = rproc_to_trproc(rproc);
> + if (!trproc) {
> + ret = -EINVAL;
> + goto out;
> + }
> +
> + rproc_tee_prepare_args(trproc, TA_RPROC_FW_CMD_STOP, &arg, param, 0);
> +
> + ret = tee_client_invoke_func(rproc_tee_ctx.tee_ctx, &arg, param);
> + if (ret < 0 || arg.ret != 0) {
> + dev_err(rproc_tee_ctx.dev,
> + "TA_RPROC_FW_CMD_STOP invoke failed TEE err: %#x, ret:%d\n", arg.ret, ret);
> + if (!ret)
> + ret = -EIO;
> + }
> +
> +out:
> + mutex_unlock(&ctx_lock);
> + return ret;
> +}
> +EXPORT_SYMBOL_GPL(rproc_tee_stop);
> +
> +static const struct tee_client_device_id rproc_tee_id_table[] = {
> + {UUID_INIT(0x80a4c275, 0x0a47, 0x4905, 0x82, 0x85, 0x14, 0x86, 0xa9, 0x77, 0x1a, 0x08)},
> + {}
> +};
> +
> +/**
> + * rproc_tee_register() - Register a remote processor controlled by the TEE application.
> + * @dev: Pointer to client rproc device
> + * @rproc: Pointer to the struct rproc representing the remote processor
> + * @rproc_id: ID of the remote processor
> + *
> + * This function registers a remote processor that will be managed by a TEE
> + * application,by opening a session with the TEE client.
> + *
> + * Return: Returns 0 on success, or an error code on failure
> + */
> +int rproc_tee_register(struct device *dev, struct rproc *rproc, unsigned int rproc_id)
> +{
> + struct tee_param param[MAX_TEE_PARAM_ARRAY_MEMBER];
> + struct tee_ioctl_open_session_arg sess_arg;
> + struct tee_client_device *tee_device;
> + struct rproc_tee *trproc;
> + struct device_link *link;
> + int ret;
> +
> + ret = mutex_lock_interruptible(&ctx_lock);
> + if (ret)
> + return ret;
> +
> + /*
> + * Test if the device has been probed by the TEE bus. In case of failure,
> + * we ignore the reason. The bus could be not yet probed or the service
> + * not available in the secure firmware.The assumption in such a case is
> + * that the TEE remoteproc is not probed.
> + */
> + if (!rproc_tee_ctx.dev) {
> + ret = -EPROBE_DEFER;
> + goto out;
> + }
> +
> + trproc = kzalloc(sizeof(*trproc), GFP_KERNEL);
> + if (!trproc) {
> + ret = -ENOMEM;
> + goto out;
> + }
> +
> + tee_device = to_tee_client_device(rproc_tee_ctx.dev);
> + memset(&sess_arg, 0, sizeof(sess_arg));
> +
> + memcpy(sess_arg.uuid, tee_device->id.uuid.b, TEE_IOCTL_UUID_LEN);
> +
> + sess_arg.clnt_login = TEE_IOCTL_LOGIN_REE_KERNEL;
> + sess_arg.num_params = 1;
> +
> + param[0] = (struct tee_param) {
> + .attr = TEE_IOCTL_PARAM_ATTR_TYPE_VALUE_INPUT,
> + .u.value.a = rproc_id,
> + };
> +
> + ret = tee_client_open_session(rproc_tee_ctx.tee_ctx, &sess_arg, param);
> + if (ret < 0 || sess_arg.ret != 0) {
> + dev_err(dev, "tee_client_open_session failed, err: %#x\n", sess_arg.ret);
> + ret = -EINVAL;
> + goto free_tproc;
> + }
> +
> + trproc->rproc_id = rproc_id;
> + trproc->session_id = sess_arg.session;
> +
> + trproc->rproc = rproc;
> +
> + /*
> + * Create device link between the rproc device and the TEE device to
> + * ensure that the rproc device is removed accordingly to a remove of
> + * the remoteproc tee device.
> + */
> + link = device_link_add(dev, rproc_tee_ctx.dev, DL_FLAG_AUTOREMOVE_CONSUMER);
> + if (!link) {
> + ret = -ENOMEM;
> + goto close_tee;
> + }
> + list_add_tail(&trproc->node, &rproc_tee_ctx.sessions);
> +
> + mutex_unlock(&ctx_lock);
> +
> + return 0;
> +
> +close_tee:
> + if (tee_client_close_session(rproc_tee_ctx.tee_ctx, trproc->session_id))
> + dev_err(rproc_tee_ctx.dev, "tee_client_close_session failed\n");
> +free_tproc:
> + kfree(trproc);
> +out:
> + mutex_unlock(&ctx_lock);
> +
> + return ret;
> +}
> +EXPORT_SYMBOL_GPL(rproc_tee_register);
> +
> +/**
> + * rproc_tee_unregister - Register a remote processor controlled by the TEE application.
> + * @dev: Pointer to client rproc device
> + * @rproc: Pointer to the struct rproc representing the remote processor
> + *
> + * This function unregisters a remote processor previously registered by the
> + * rproc_tee_register() function.
> + *
> + * Return: Returns 0 on success, or an error code on failure
> + */
> +int rproc_tee_unregister(struct device *dev, struct rproc *rproc)
> +{
> + struct rproc_tee *trproc;
> + int ret;
> +
> + ret = mutex_lock_interruptible(&ctx_lock);
> + if (ret)
> + return ret;
> +
> + if (!rproc_tee_ctx.dev) {
> + ret = -EPROBE_DEFER;
> + goto out;
> + }
> +
> + trproc = rproc_to_trproc(rproc);
> + if (!trproc) {
> + ret = -EINVAL;
> + goto out;
> + }
> +
> + ret = tee_client_close_session(rproc_tee_ctx.tee_ctx, trproc->session_id);
> + if (ret < 0)
> + dev_err(rproc_tee_ctx.dev, "tee_client_close_session failed, err: %#x\n", ret);
> +
> + list_del(&trproc->node);
> + kfree(trproc);
> +
> +out:
> + mutex_unlock(&ctx_lock);
> + return ret;
> +}
> +EXPORT_SYMBOL_GPL(rproc_tee_unregister);
> +
> +static int rproc_tee_ctx_match(struct tee_ioctl_version_data *ver, const void *data)
> +{
> + /* Today we support only the OP-TEE, could be extend to other tees */
> + return (ver->impl_id == TEE_IMPL_ID_OPTEE);
> +}
> +
> +static int rproc_tee_probe(struct device *dev)
> +{
> + struct tee_context *tee_ctx;
> + int ret;
> +
> + /* Open context with TEE driver */
> + tee_ctx = tee_client_open_context(NULL, rproc_tee_ctx_match, NULL, NULL);
> + if (IS_ERR(tee_ctx))
> + return PTR_ERR(tee_ctx);
> +
> + ret = mutex_lock_interruptible(&ctx_lock);
> + if (ret)
> + return ret;
> +
> + rproc_tee_ctx.dev = dev;
> + rproc_tee_ctx.tee_ctx = tee_ctx;
> + INIT_LIST_HEAD(&rproc_tee_ctx.sessions);
> + mutex_unlock(&ctx_lock);
> +
> + return 0;
> +}

As you mentioned above, this could be extended to other TEEs. If so, is it possible for probe
to be called multiple times if we we have other TEE devices exposing the firmware authentication
service? In that case, I think rproc_tee_ctx should be dynamically initializated instead of being
static. And since we are creating a link between the Rproc device and TEE device, a call to a
function like rproc_tee_start() could retreive the associated TEE device, and then the associated
rproc_tee? :)

Thanks,
Harshal
> +
> +static int rproc_tee_remove(struct device *dev)
> +{
> + mutex_lock(&ctx_lock);
> + tee_client_close_context(rproc_tee_ctx.tee_ctx);
> + rproc_tee_ctx.dev = NULL;
> + rproc_tee_ctx.tee_ctx = NULL;
> + mutex_unlock(&ctx_lock);
> +
> + return 0;
> +}
> +
> +MODULE_DEVICE_TABLE(tee, rproc_tee_id_table);
> +
> +static struct tee_client_driver rproc_tee_fw_driver = {
> + .id_table = rproc_tee_id_table,
> + .driver = {
> + .name = KBUILD_MODNAME,
> + .bus = &tee_bus_type,
> + .probe = rproc_tee_probe,
> + .remove = rproc_tee_remove,
> + },
> +};
> +
> +static int __init rproc_tee_fw_mod_init(void)
> +{
> + mutex_init(&ctx_lock);
> +
> + return driver_register(&rproc_tee_fw_driver.driver);
> +}
> +
> +static void __exit rproc_tee_fw_mod_exit(void)
> +{
> + driver_unregister(&rproc_tee_fw_driver.driver);
> +}
> +
> +module_init(rproc_tee_fw_mod_init);
> +module_exit(rproc_tee_fw_mod_exit);
> +
> +MODULE_DESCRIPTION("remote processor TEE module");
> +MODULE_LICENSE("GPL");
> diff --git a/include/linux/remoteproc_tee.h b/include/linux/remoteproc_tee.h
> new file mode 100644
> index 000000000000..a5fdc1627774
> --- /dev/null
> +++ b/include/linux/remoteproc_tee.h
> @@ -0,0 +1,87 @@
> +/* SPDX-License-Identifier: GPL-2.0-or-later */
> +/*
> + * Copyright(c) 2025 STMicroelectronics
> + */
> +
> +#ifndef REMOTEPROC_TEE_H
> +#define REMOTEPROC_TEE_H
> +
> +#include <linux/tee_drv.h>
> +#include <linux/firmware.h>
> +#include <linux/remoteproc.h>
> +
> +#if IS_ENABLED(CONFIG_REMOTEPROC_TEE)
> +
> +int rproc_tee_register(struct device *dev, struct rproc *rproc, unsigned int rproc_id);
> +int rproc_tee_unregister(struct device *dev, struct rproc *rproc);
> +int rproc_tee_parse_fw(struct rproc *rproc, const struct firmware *fw);
> +int rproc_tee_load_fw(struct rproc *rproc, const struct firmware *fw);
> +void rproc_tee_release_fw(struct rproc *rproc);
> +struct resource_table *rproc_tee_find_loaded_rsc_table(struct rproc *rproc,
> + const struct firmware *fw);
> +int rproc_tee_start(struct rproc *rproc);
> +int rproc_tee_stop(struct rproc *rproc);
> +
> +#else
> +
> +static inline int rproc_tee_register(struct device *dev, struct rproc *rproc, unsigned int rproc_id)
> +{
> + return -ENODEV;
> +}
> +
> +static inline int rproc_tee_parse_fw(struct rproc *rproc, const struct firmware *fw)
> +{
> + /* This shouldn't be possible */
> + WARN_ON(1);
> +
> + return 0;
> +}
> +
> +static inline int rproc_tee_unregister(struct device *dev, struct rproc *rproc)
> +{
> + /* This shouldn't be possible */
> + WARN_ON(1);
> +
> + return 0;
> +}
> +
> +static inline int rproc_tee_load_fw(struct rproc *rproc, const struct firmware *fw)
> +{
> + /* This shouldn't be possible */
> + WARN_ON(1);
> +
> + return 0;
> +}
> +
> +static inline int rproc_tee_start(struct rproc *rproc)
> +{
> + /* This shouldn't be possible */
> + WARN_ON(1);
> +
> + return 0;
> +}
> +
> +static inline int rproc_tee_stop(struct rproc *rproc)
> +{
> + /* This shouldn't be possible */
> + WARN_ON(1);
> +
> + return 0;
> +}
> +
> +static inline void rproc_tee_release_fw(struct rproc *rproc)
> +{
> + /* This shouldn't be possible */
> + WARN_ON(1);
> +}
> +
> +static inline struct resource_table *
> +rproc_tee_find_loaded_rsc_table(struct rproc *rproc, const struct firmware *fw)
> +{
> + /* This shouldn't be possible */
> + WARN_ON(1);
> +
> + return NULL;
> +}
> +#endif /* CONFIG_REMOTEPROC_TEE */
> +#endif /* REMOTEPROC_TEE_H */