Message-ID: <e5a234c7-0f8d-4b52-95fb-82371c8e4460@quicinc.com>
Date: Mon, 4 Aug 2025 14:56:18 +0530
From: Harshal Dev <quic_hdev@...cinc.com>
To: Arnaud POULIQUEN <arnaud.pouliquen@...s.st.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

Hi Arnaud,

On 8/1/2025 12:53 PM, Arnaud POULIQUEN wrote:
> 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.
> 

My thought process on this stems from 1) the recent ARM FF-A developments and 2) from the current
implementation of the TEE subsystem which allows multiple back-end drivers to register themselves
via the tee_device_register() API. This means, that it's possible to have a configuration
where a platform supports multiple TEEs running as Secure Partitions via FF-A, and each of those
TEEs register their services as PTA devices on the TEE bus.

However, I do not really know if it's possible to have a UUID collision in such a case, which
would lead to rproc_tee_probe() being called twice above, which is why I raised this question. :)

All of this aside, I realize now that other TEE client drivers are also implemented with a static
private data similar to how you are doing it. So perhaps we can think of this as a later
enhancement if we believe that the scenario I am describing is not possible in the near future..

Thanks,
Harshal
> 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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