Message-ID: <7c77dba4-27f9-4840-b9aa-253119308519@foss.st.com>
Date: Fri, 1 Aug 2025 09:23:40 +0200
From: Arnaud POULIQUEN <arnaud.pouliquen@...s.st.com>
To: Harshal Dev <quic_hdev@...cinc.com>,
        Bjorn Andersson
	<andersson@...nel.org>,
        Mathieu Poirier <mathieu.poirier@...aro.org>,
        "Jens
 Wiklander" <jens.wiklander@...aro.org>,
        Rob Herring <robh+dt@...nel.org>,
        Krzysztof Kozlowski <krzk+dt@...nel.org>,
        Conor Dooley <conor+dt@...nel.org>
CC: <linux-stm32@...md-mailman.stormreply.com>,
        <linux-arm-kernel@...ts.infradead.org>,
        <linux-remoteproc@...r.kernel.org>, <linux-kernel@...r.kernel.org>,
        <op-tee@...ts.trustedfirmware.org>, <devicetree@...r.kernel.org>
Subject: Re: [PATCH v19 2/6] remoteproc: Add TEE support

Hello Harshal,


On 7/31/25 12:25, Harshal Dev wrote:
> 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@...s.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@...s.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? :)

I have never seen a use case that requires multiple instances, but perhaps you
have some?

We can expect only one TEE, which could be OP-TEE, Trusty, or another.
The device is associated with a unique UUID, so only one instance is expected.

That said, making this driver support multiple instances seems like a valid
future enhancement. However, I would suggest implementing it as a second step
when there is a concrete need.

Thanks,
Arnaud

> 
> 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 */
> 

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