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Date: Mon, 1 Apr 2024 09:54:28 -0600
From: Mathieu Poirier <mathieu.poirier@linaro.org>
To: Arnaud POULIQUEN <arnaud.pouliquen@foss.st.com>
Cc: Bjorn Andersson <andersson@kernel.org>,
	Jens Wiklander <jens.wiklander@linaro.org>,
	Rob Herring <robh+dt@kernel.org>,
	Krzysztof Kozlowski <krzysztof.kozlowski+dt@linaro.org>,
	Conor Dooley <conor+dt@kernel.org>,
	linux-stm32@st-md-mailman.stormreply.com,
	linux-arm-kernel@lists.infradead.org,
	linux-remoteproc@vger.kernel.org, linux-kernel@vger.kernel.org,
	op-tee@lists.trustedfirmware.org, devicetree@vger.kernel.org
Subject: Re: [PATCH v4 1/4] remoteproc: Add TEE support
Message-ID: <ZgrYtDv9em1+KV6F@p14s>
References: <20240308144708.62362-1-arnaud.pouliquen@foss.st.com>
 <20240308144708.62362-2-arnaud.pouliquen@foss.st.com>
 <ZgGqfItYtkUUvlxf@p14s>
 <5bb9f583-351d-45a4-90e1-ce0b8dde8ce2@foss.st.com>
 <ZgRSS76mtc4JBAJP@p14s>
 <a4a1f938-d185-46d7-9f57-af7bf3a65e9c@foss.st.com>
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In-Reply-To: <a4a1f938-d185-46d7-9f57-af7bf3a65e9c@foss.st.com>

On Fri, Mar 29, 2024 at 09:58:11AM +0100, Arnaud POULIQUEN wrote:
> Hello Mathieu,
> 
> On 3/27/24 18:07, Mathieu Poirier wrote:
> > On Tue, Mar 26, 2024 at 08:18:23PM +0100, Arnaud POULIQUEN wrote:
> >> Hello Mathieu,
> >>
> >> On 3/25/24 17:46, Mathieu Poirier wrote:
> >>> On Fri, Mar 08, 2024 at 03:47:05PM +0100, 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 secure part this device offers a client
> >>>
> >>> Device or driver?  I thought I touched on that before.
> >>
> >> Right, I changed the first instance and missed this one
> >>
> >>>
> >>>> interface to load a firmware in the secure part.
> >>>> This firmware could be authenticated by the secure trusted application.
> >>>>
> >>>> Signed-off-by: Arnaud Pouliquen <arnaud.pouliquen@foss.st.com>
> >>>> ---
> >>>> Updates from V3:
> >>>> - rework TEE_REMOTEPROC description in Kconfig
> >>>> - fix some namings
> >>>> - add tee_rproc_parse_fw  to support rproc_ops::parse_fw
> >>>> - add proc::tee_interface;
> >>>> - add rproc struct as parameter of the tee_rproc_register() function
> >>>> ---
> >>>>  drivers/remoteproc/Kconfig          |  10 +
> >>>>  drivers/remoteproc/Makefile         |   1 +
> >>>>  drivers/remoteproc/tee_remoteproc.c | 434 ++++++++++++++++++++++++++++
> >>>>  include/linux/remoteproc.h          |   4 +
> >>>>  include/linux/tee_remoteproc.h      | 112 +++++++
> >>>>  5 files changed, 561 insertions(+)
> >>>>  create mode 100644 drivers/remoteproc/tee_remoteproc.c
> >>>>  create mode 100644 include/linux/tee_remoteproc.h
> >>>>
> >>>> diff --git a/drivers/remoteproc/Kconfig b/drivers/remoteproc/Kconfig
> >>>> index 48845dc8fa85..2cf1431b2b59 100644
> >>>> --- a/drivers/remoteproc/Kconfig
> >>>> +++ b/drivers/remoteproc/Kconfig
> >>>> @@ -365,6 +365,16 @@ config XLNX_R5_REMOTEPROC
> >>>>  
> >>>>  	  It's safe to say N if not interested in using RPU r5f cores.
> >>>>  
> >>>> +
> >>>> +config TEE_REMOTEPROC
> >>>> +	tristate "remoteproc support by a TEE application"
> >>>
> >>> s/remoteproc/Remoteproc
> >>>
> >>>> +	depends on OPTEE
> >>>> +	help
> >>>> +	  Support a remote processor with a TEE application. The Trusted
> >>>> +	  Execution Context is responsible for loading the trusted firmware
> >>>> +	  image and managing the remote processor's lifecycle.
> >>>> +	  This can be either built-in or a loadable module.
> >>>> +
> >>>>  endif # REMOTEPROC
> >>>>  
> >>>>  endmenu
> >>>> diff --git a/drivers/remoteproc/Makefile b/drivers/remoteproc/Makefile
> >>>> index 91314a9b43ce..fa8daebce277 100644
> >>>> --- a/drivers/remoteproc/Makefile
> >>>> +++ b/drivers/remoteproc/Makefile
> >>>> @@ -36,6 +36,7 @@ obj-$(CONFIG_RCAR_REMOTEPROC)		+= rcar_rproc.o
> >>>>  obj-$(CONFIG_ST_REMOTEPROC)		+= st_remoteproc.o
> >>>>  obj-$(CONFIG_ST_SLIM_REMOTEPROC)	+= st_slim_rproc.o
> >>>>  obj-$(CONFIG_STM32_RPROC)		+= stm32_rproc.o
> >>>> +obj-$(CONFIG_TEE_REMOTEPROC)		+= tee_remoteproc.o
> >>>>  obj-$(CONFIG_TI_K3_DSP_REMOTEPROC)	+= ti_k3_dsp_remoteproc.o
> >>>>  obj-$(CONFIG_TI_K3_R5_REMOTEPROC)	+= ti_k3_r5_remoteproc.o
> >>>>  obj-$(CONFIG_XLNX_R5_REMOTEPROC)	+= xlnx_r5_remoteproc.o
> >>>> diff --git a/drivers/remoteproc/tee_remoteproc.c b/drivers/remoteproc/tee_remoteproc.c
> >>>> new file mode 100644
> >>>> index 000000000000..c855210e52e3
> >>>> --- /dev/null
> >>>> +++ b/drivers/remoteproc/tee_remoteproc.c
> >>>> @@ -0,0 +1,434 @@
> >>>> +// SPDX-License-Identifier: GPL-2.0-or-later
> >>>> +/*
> >>>> + * Copyright (C) STMicroelectronics 2024 - All Rights Reserved
> >>>> + * Author: Arnaud Pouliquen <arnaud.pouliquen@foss.st.com>
> >>>> + */
> >>>> +
> >>>> +#include <linux/firmware.h>
> >>>> +#include <linux/io.h>
> >>>> +#include <linux/module.h>
> >>>> +#include <linux/remoteproc.h>
> >>>> +#include <linux/slab.h>
> >>>> +#include <linux/tee_drv.h>
> >>>> +#include <linux/tee_remoteproc.h>
> >>>> +
> >>>> +#include "remoteproc_internal.h"
> >>>> +
> >>>> +#define MAX_TEE_PARAM_ARRY_MEMBER	4
> >>>> +
> >>>> +/*
> >>>> + * Authentication of the firmware and load in the remote processor memory
> >>>> + *
> >>>> + * [in]  params[0].value.a:	unique 32bit identifier of the remote processor
> >>>> + * [in]	 params[1].memref:	buffer containing the image of the buffer
> >>>> + */
> >>>> +#define TA_RPROC_FW_CMD_LOAD_FW		1
> >>>> +
> >>>> +/*
> >>>> + * Start the remote processor
> >>>> + *
> >>>> + * [in]  params[0].value.a:	unique 32bit identifier of the remote processor
> >>>> + */
> >>>> +#define TA_RPROC_FW_CMD_START_FW	2
> >>>> +
> >>>> +/*
> >>>> + * Stop the remote processor
> >>>> + *
> >>>> + * [in]  params[0].value.a:	unique 32bit identifier of the remote processor
> >>>> + */
> >>>> +#define TA_RPROC_FW_CMD_STOP_FW		3
> >>>> +
> >>>> +/*
> >>>> + * Return the address of the resource table, or 0 if not found
> >>>> + * No check is done to verify that the address returned is accessible by
> >>>> + * the non secure context. If the resource table is loaded in a protected
> >>>> + * memory the access by the non secure context will lead to a data abort.
> >>>> + *
> >>>> + * [in]  params[0].value.a:	unique 32bit identifier of the remote processor
> >>>> + * [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
> >>>> +
> >>>> +/*
> >>>> + * Return the address of the core dump
> >>>> + *
> >>>> + * [in]  params[0].value.a:	unique 32bit identifier of the remote processor
> >>>> + * [out] params[1].memref:	address of the core dump image if exist,
> >>>> + *				else return Null
> >>>> + */
> >>>> +#define TA_RPROC_FW_CMD_GET_COREDUMP	5
> >>>> +
> >>>> +struct tee_rproc_context {
> >>>> +	struct list_head sessions;
> >>>> +	struct tee_context *tee_ctx;
> >>>> +	struct device *dev;
> >>>> +};
> >>>> +
> >>>> +static struct tee_rproc_context *tee_rproc_ctx;
> >>>> +
> >>>> +static void tee_rproc_prepare_args(struct tee_rproc *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_ARRY_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,
> >>>> +	};
> >>>> +}
> >>>> +
> >>>> +int tee_rproc_load_fw(struct rproc *rproc, const struct firmware *fw)
> >>>> +{
> >>>> +	struct tee_ioctl_invoke_arg arg;
> >>>> +	struct tee_param param[MAX_TEE_PARAM_ARRY_MEMBER];
> >>>> +	struct tee_rproc *trproc = rproc->tee_interface;
> >>>> +	struct tee_shm *fw_shm;
> >>>> +	int ret;
> >>>
> >>> Declarations in reverse ascending order here and everywhere in the driver.
> >>> Sometimes it is done properly, sometimes it isn't. 
> >>>
> >>>> +
> >>>> +	if (!trproc)
> >>>> +		return -EINVAL;
> >>>> +
> >>>> +	fw_shm = tee_shm_register_kernel_buf(tee_rproc_ctx->tee_ctx, (void *)fw->data, fw->size);
> >>>> +	if (IS_ERR(fw_shm))
> >>>> +		return PTR_ERR(fw_shm);
> >>>> +
> >>>> +	tee_rproc_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(tee_rproc_ctx->tee_ctx, &arg, param);
> >>>> +	if (ret < 0 || arg.ret != 0) {
> >>>> +		dev_err(tee_rproc_ctx->dev,
> >>>> +			"TA_RPROC_FW_CMD_LOAD_FW invoke failed TEE err: %x, ret:%x\n",
> >>>> +			arg.ret, ret);
> >>>> +		if (!ret)
> >>>> +			ret = -EIO;
> >>>> +	}
> >>>> +
> >>>> +	tee_shm_free(fw_shm);
> >>>> +
> >>>> +	return ret;
> >>>> +}
> >>>> +EXPORT_SYMBOL_GPL(tee_rproc_load_fw);
> >>>> +
> >>>> +struct resource_table *tee_rproc_get_loaded_rsc_table(struct rproc *rproc, size_t *table_sz)
> >>>> +{
> >>>> +	struct tee_ioctl_invoke_arg arg;
> >>>> +	struct tee_param param[MAX_TEE_PARAM_ARRY_MEMBER];
> >>>> +	struct tee_rproc *trproc = rproc->tee_interface;
> >>>> +	struct resource_table *rsc_table;
> >>>> +	int ret;
> >>>> +
> >>>> +	if (!trproc)
> >>>> +		return ERR_PTR(-EINVAL);
> >>>> +
> >>>> +	tee_rproc_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(tee_rproc_ctx->tee_ctx, &arg, param);
> >>>> +	if (ret < 0 || arg.ret != 0) {
> >>>> +		dev_err(tee_rproc_ctx->dev,
> >>>> +			"TA_RPROC_FW_CMD_GET_RSC_TABLE invoke failed TEE err: %x, ret:%x\n",
> >>>> +			arg.ret, ret);
> >>>> +		return ERR_PTR(-EIO);
> >>>> +	}
> >>>> +
> >>>> +	*table_sz = param[2].u.value.a;
> >>>> +
> >>>> +	/* If the size is null no resource table defined in the image */
> >>>> +	if (!*table_sz)
> >>>> +		return NULL;
> >>>> +
> >>>> +	/* Store the resource table address that would be updated by the remote core. */
> >>>> +	rsc_table = ioremap_wc(param[1].u.value.a, *table_sz);
> >>>> +	if (IS_ERR_OR_NULL(rsc_table)) {
> >>>> +		dev_err(tee_rproc_ctx->dev, "Unable to map memory region: %lld+%zx\n",
> >>>> +			param[1].u.value.a, *table_sz);
> >>>> +		return ERR_PTR(-ENOMEM);
> >>>> +	}
> >>>> +
> >>>> +	return rsc_table;
> >>>> +}
> >>>> +EXPORT_SYMBOL_GPL(tee_rproc_get_loaded_rsc_table);
> >>>> +
> >>>> +int tee_rproc_parse_fw(struct rproc *rproc, const struct firmware *fw)
> >>>> +{
> >>>> +	struct tee_rproc *trproc = rproc->tee_interface;
> >>>> +	struct resource_table *rsc_table;
> >>>> +	size_t table_sz;
> >>>> +	int ret;
> >>>> +
> >>>> +	ret = tee_rproc_load_fw(rproc, fw);
> >>>> +	if (ret)
> >>>> +		return ret;
> >>>> +
> >>>> +	rsc_table = tee_rproc_get_loaded_rsc_table(rproc, &table_sz);
> >>>> +	if (IS_ERR(rsc_table))
> >>>> +		return PTR_ERR(rsc_table);
> >>>> +
> >>>> +	/* Create a copy of the resource table to have same behaviour than the elf loader. */
> >>>> +	rproc->cached_table = kmemdup(rsc_table, table_sz, GFP_KERNEL);
> >>>> +	if (!rproc->cached_table)
> >>>> +		return -ENOMEM;
> >>>
> >>> Why not ->table_ptr and setting ->cached_table to NULL?
> >>
> >> It was my plan preparing this version. But during implementarion it looks
> >> to me that having exactly same behavior than the ELF loader would be
> >> simpler to maintain the remoteproc avoiding to update in the remoteproc core
> >> to manage for the cached resource table (see also my comment below abourt recovery)
> >> That why I propose this implementation
> >>
> >> That said what you proposal should also work (with some updates in
> >> remoteproc_core for the management of the cached table).
> >>
> > 
> > Yes
> > 
> >> So please just comfirm your preference.
> >>
> > 
> > Definitely keep ->cached_table to NULL.  
> > 
> >>>
> >>>> +
> >>>> +	rproc->table_ptr = rproc->cached_table;
> >>>> +	rproc->table_sz = table_sz;
> >>>> +	trproc->rsc_table = rsc_table;
> >>>
> >>> I really don't see why this is needed, please remove and use rproc->table_ptr
> >>> instead.
> >>
> >> I need to store it for the iounmap in tee_rproc_remove.
> > 
> > iounmap(entry->rproc->rsc_table);
> > 
> > What am I missing?
> 
> rproc->rsc_table is a field that can be updated by remoteproc_core.
> How can we garanty in tee_remoteproc that it still points to the mapped resource
> table?

By making sure the core doesn't touch rproc->rsc_table when
rproc->tee_interface is valid.

> As the remoteproc_tee maps the pointer, it seems reliable that it stores it for
> unmap.
> 

Doing so creates a shadow value that is confusing and really hard to maintain
going forward.

> Seems also that I also missed to  handle the case where rproc_fw_boot() fails[3]
> (not done yet).
> 
> [3]https://elixir.bootlin.com/linux/latest/source/drivers/remoteproc/remoteproc_core.c#L1442
> 
> 
> > 
> >>
> >>>
> >>>> +
> >>>> +	return 0;
> >>>> +}
> >>>> +EXPORT_SYMBOL_GPL(tee_rproc_parse_fw);
> >>>> +
> >>>> +struct resource_table *tee_rproc_find_loaded_rsc_table(struct rproc *rproc,
> >>>> +						       const struct firmware *fw)
> >>>> +{
> >>>> +	struct tee_rproc *trproc = rproc->tee_interface;
> >>>> +	struct resource_table *rsc_table;
> >>>> +	size_t table_sz;
> >>>> +
> >>>> +	if (!trproc)
> >>>> +		return ERR_PTR(-EINVAL);
> >>>> +
> >>>> +	/* Check if the resourse table has already been obtained in tee_rproc_parse_fw() */
> >>>> +	if (trproc->rsc_table)
> >>>> +		return trproc->rsc_table;
> >>>
> >>> Again, why not simply use rproc->rsc_table?  This function should only return
> >>> the resource table that was set in tee_rproc_parse_fw(). 
> >>
> >> In case of recovery rproc->_rsc_table point to the cached table [1]
> >  
> > In [1], on line 1554, add a check for rproc->tee_interface and if it is valid
> > call rproc_find_loaded_rsc_table(). 
> > 
> >> and we need to reapply the configuration in rproc_start() called during the
> >> recovery[2]
> > 
> > 1) Rename rproc_set_rsc_table() to rproc_set_rsc_table_on_attach()
> > 2) Introduce a new function called rproc_set_rsc_table_on_start()
> > 3) Move code from [2], line 1278 to 1292, to that new function.  In the new
> > function, add a check on rproc->tee_interface.  If it is valid then call
> > rproc_find_loaded_rsc_table().
> > 4) in rproc_start(), replace lines 1278 to 1292 with a call to
> > rproc_set_rsc_table_on_start().
> 
> 
> I will try this
> 

Ok

> Thanks!
> Arnaud
> 
> > 
> >> [1]https://elixir.bootlin.com/linux/latest/source/drivers/remoteproc/remoteproc_core.c#L1586
> >> [2]https://elixir.bootlin.com/linux/latest/source/drivers/remoteproc/remoteproc_core.c#L1287
> >>
> >>>
> >>>> +
> >>>> +	rsc_table = tee_rproc_get_loaded_rsc_table(rproc, &table_sz);
> >>>> +	if (IS_ERR(rsc_table))
> >>>> +		return rsc_table;
> >>>> +
> >>>> +	rproc->table_sz = table_sz;
> >>>> +	trproc->rsc_table = rsc_table;
> >>>> +
> >>>> +	return rsc_table;
> >>>> +}
> >>>> +EXPORT_SYMBOL_GPL(tee_rproc_find_loaded_rsc_table);
> >>>> +
> >>>> +int tee_rproc_start(struct rproc *rproc)
> >>>> +{
> >>>> +	struct tee_ioctl_invoke_arg arg;
> >>>> +	struct tee_param param[MAX_TEE_PARAM_ARRY_MEMBER];
> >>>> +	struct tee_rproc *trproc = rproc->tee_interface;
> >>>> +	int ret;
> >>>> +
> >>>> +	if (!trproc)
> >>>> +		return -EINVAL;
> >>>> +
> >>>> +	tee_rproc_prepare_args(trproc, TA_RPROC_FW_CMD_START_FW, &arg, param, 0);
> >>>> +
> >>>> +	ret = tee_client_invoke_func(tee_rproc_ctx->tee_ctx, &arg, param);
> >>>> +	if (ret < 0 || arg.ret != 0) {
> >>>> +		dev_err(tee_rproc_ctx->dev,
> >>>> +			"TA_RPROC_FW_CMD_START_FW invoke failed TEE err: %x, ret:%x\n",
> >>>> +			arg.ret, ret);
> >>>> +		if (!ret)
> >>>> +			ret = -EIO;
> >>>> +	}
> >>>> +
> >>>> +	return ret;
> >>>> +}
> >>>> +EXPORT_SYMBOL_GPL(tee_rproc_start);
> >>>> +
> >>>> +int tee_rproc_stop(struct rproc *rproc)
> >>>> +{
> >>>> +	struct tee_ioctl_invoke_arg arg;
> >>>> +	struct tee_param param[MAX_TEE_PARAM_ARRY_MEMBER];
> >>>> +	struct tee_rproc *trproc = rproc->tee_interface;
> >>>> +	int ret;
> >>>> +
> >>>> +	if (!trproc)
> >>>> +		return -EINVAL;
> >>>> +
> >>>> +	tee_rproc_prepare_args(trproc, TA_RPROC_FW_CMD_STOP_FW, &arg, param, 0);
> >>>> +
> >>>> +	ret = tee_client_invoke_func(tee_rproc_ctx->tee_ctx, &arg, param);
> >>>> +	if (ret < 0 || arg.ret != 0) {
> >>>> +		dev_err(tee_rproc_ctx->dev,
> >>>> +			"TA_RPROC_FW_CMD_STOP_FW invoke failed TEE err: %x, ret:%x\n",
> >>>> +			arg.ret, ret);
> >>>> +		if (!ret)
> >>>> +			ret = -EIO;
> >>>> +	}
> >>>> +
> >>>> +	if (!rproc->table_ptr)
> >>>> +		return ret;
> >>>> +
> >>>> +	iounmap(trproc->rsc_table);
> >>>> +	trproc->rsc_table = NULL;
> >>>> +	rproc->table_ptr = NULL;
> >>>> +
> >>>> +	return 0;
> >>>> +}
> >>>> +EXPORT_SYMBOL_GPL(tee_rproc_stop);
> >>>> +
> >>>> +static const struct tee_client_device_id stm32_tee_rproc_id_table[] = {
> >>>> +	{UUID_INIT(0x80a4c275, 0x0a47, 0x4905,
> >>>> +		   0x82, 0x85, 0x14, 0x86, 0xa9, 0x77, 0x1a, 0x08)},
> >>>> +	{}
> >>>> +};
> >>>> +
> >>>> +struct tee_rproc *tee_rproc_register(struct device *dev, struct rproc *rproc, unsigned int rproc_id)
> >>>> +{
> >>>> +	struct tee_client_device *tee_device;
> >>>> +	struct tee_ioctl_open_session_arg sess_arg;
> >>>> +	struct tee_param param[MAX_TEE_PARAM_ARRY_MEMBER];
> >>>> +	struct tee_rproc *trproc;
> >>>> +	int 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 (!tee_rproc_ctx)
> >>>> +		return ERR_PTR(-EPROBE_DEFER);
> >>>> +
> >>>> +	trproc =  devm_kzalloc(dev, sizeof(*trproc), GFP_KERNEL);
> >>>> +	if (!trproc)
> >>>> +		return ERR_PTR(-ENOMEM);
> >>>> +
> >>>> +	tee_device = to_tee_client_device(tee_rproc_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(tee_rproc_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);
> >>>> +		return ERR_PTR(-EINVAL);
> >>>> +	}
> >>>> +
> >>>> +	trproc->parent =  dev;
> >>>> +	trproc->rproc_id = rproc_id;
> >>>> +	trproc->session_id = sess_arg.session;
> >>>> +
> >>>> +	trproc->rproc = rproc;
> >>>> +	rproc->tee_interface = trproc;
> >>>> +
> >>>> +	list_add_tail(&trproc->node, &tee_rproc_ctx->sessions);
> >>>> +
> >>>> +	return trproc;
> >>>
> >>> Once this function was called by a client, what prevents a user from unloading
> >>> the tee_remoteproc module and breaking everything?
> >>
> >> Good point! seems better toremove the module build capability
> >>
> > 
> > I was thinking more along the lines of try_module_get() and module_put() to
> > avoid bloating the core.
> > 
> >> Thanks,
> >> Arnaud
> >>
> >>>
> >>>> +}
> >>>> +EXPORT_SYMBOL_GPL(tee_rproc_register);
> >>>> +
> >>>> +int tee_rproc_unregister(struct tee_rproc *trproc)
> >>>> +{
> >>>
> >>> If you pass a struct_rproc instead of a struct tee_rproc there is no need for
> >>> tee_rproc::rproc, which is only ever used in this function.
> >>>
> >>>
> >>>> +	struct rproc *rproc = trproc->rproc;
> >>>> +	int ret;
> >>>> +
> >>>> +	ret = tee_client_close_session(tee_rproc_ctx->tee_ctx, trproc->session_id);
> >>>> +	if (ret < 0)
> >>>> +		dev_err(trproc->parent,	"tee_client_close_session failed, err: %x\n", ret);
> >>>> +
> >>>> +	list_del(&trproc->node);
> >>>> +	rproc->tee_interface = NULL;
> >>>> +
> >>>> +	return ret;
> >>>> +}
> >>>> +EXPORT_SYMBOL_GPL(tee_rproc_unregister);
> >>>> +
> >>>> +static int tee_rproc_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 tee_rproc_probe(struct device *dev)
> >>>> +{
> >>>> +	struct tee_context *tee_ctx;
> >>>> +	int ret;
> >>>> +
> >>>> +	/* Open context with TEE driver */
> >>>> +	tee_ctx = tee_client_open_context(NULL, tee_rproc_ctx_match, NULL, NULL);
> >>>> +	if (IS_ERR(tee_ctx))
> >>>> +		return PTR_ERR(tee_ctx);
> >>>> +
> >>>> +	tee_rproc_ctx = devm_kzalloc(dev, sizeof(*tee_ctx), GFP_KERNEL);
> >>>> +	if (!tee_rproc_ctx) {
> >>>> +		ret = -ENOMEM;
> >>>> +		goto err;
> >>>> +	}
> >>>> +
> >>>> +	tee_rproc_ctx->dev = dev;
> >>>> +	tee_rproc_ctx->tee_ctx = tee_ctx;
> >>>> +	INIT_LIST_HEAD(&tee_rproc_ctx->sessions);
> >>>> +
> >>>> +	return 0;
> >>>> +err:
> >>>> +	tee_client_close_context(tee_ctx);
> >>>> +
> >>>> +	return ret;
> >>>> +}
> >>>> +
> >>>> +static int tee_rproc_remove(struct device *dev)
> >>>> +{
> >>>> +	struct tee_rproc *entry, *tmp;
> >>>> +
> >>>> +	list_for_each_entry_safe(entry, tmp, &tee_rproc_ctx->sessions, node) {
> >>>> +		tee_client_close_session(tee_rproc_ctx->tee_ctx, entry->session_id);
> >>>> +		list_del(&entry->node);
> >>>> +		if (entry->rsc_table)
> >>>> +			iounmap(entry->rsc_table);
> >>>> +		kfree(entry);
> >>>> +	}
> >>>> +
> >>>> +	tee_client_close_context(tee_rproc_ctx->tee_ctx);
> >>>> +
> >>>> +	return 0;
> >>>> +}
> >>>> +
> >>>> +MODULE_DEVICE_TABLE(tee, stm32_tee_rproc_id_table);
> >>>> +
> >>>> +static struct tee_client_driver tee_rproc_fw_driver = {
> >>>> +	.id_table	= stm32_tee_rproc_id_table,
> >>>> +	.driver		= {
> >>>> +		.name		= KBUILD_MODNAME,
> >>>> +		.bus		= &tee_bus_type,
> >>>> +		.probe		= tee_rproc_probe,
> >>>> +		.remove		= tee_rproc_remove,
> >>>> +	},
> >>>> +};
> >>>> +
> >>>> +static int __init tee_rproc_fw_mod_init(void)
> >>>> +{
> >>>> +	return driver_register(&tee_rproc_fw_driver.driver);
> >>>> +}
> >>>> +
> >>>> +static void __exit tee_rproc_fw_mod_exit(void)
> >>>> +{
> >>>> +	driver_unregister(&tee_rproc_fw_driver.driver);
> >>>> +}
> >>>> +
> >>>> +module_init(tee_rproc_fw_mod_init);
> >>>> +module_exit(tee_rproc_fw_mod_exit);
> >>>> +
> >>>> +MODULE_DESCRIPTION(" TEE remote processor control driver");
> >>>> +MODULE_LICENSE("GPL");
> >>>> diff --git a/include/linux/remoteproc.h b/include/linux/remoteproc.h
> >>>> index b4795698d8c2..8b678009e481 100644
> >>>> --- a/include/linux/remoteproc.h
> >>>> +++ b/include/linux/remoteproc.h
> >>>> @@ -503,6 +503,8 @@ enum rproc_features {
> >>>>  	RPROC_MAX_FEATURES,
> >>>>  };
> >>>>  
> >>>> +struct tee_rproc;
> >>>> +
> >>>>  /**
> >>>>   * struct rproc - represents a physical remote processor device
> >>>>   * @node: list node of this rproc object
> >>>> @@ -545,6 +547,7 @@ enum rproc_features {
> >>>>   * @cdev: character device of the rproc
> >>>>   * @cdev_put_on_release: flag to indicate if remoteproc should be shutdown on @char_dev release
> >>>>   * @features: indicate remoteproc features
> >>>> + * @tee_interface: pointer to the remoteproc tee context
> >>>>   */
> >>>>  struct rproc {
> >>>>  	struct list_head node;
> >>>> @@ -586,6 +589,7 @@ struct rproc {
> >>>>  	struct cdev cdev;
> >>>>  	bool cdev_put_on_release;
> >>>>  	DECLARE_BITMAP(features, RPROC_MAX_FEATURES);
> >>>> +	struct tee_rproc *tee_interface;
> >>>>  };
> >>>>  
> >>>>  /**
> >>>> diff --git a/include/linux/tee_remoteproc.h b/include/linux/tee_remoteproc.h
> >>>> new file mode 100644
> >>>> index 000000000000..571e47190d02
> >>>> --- /dev/null
> >>>> +++ b/include/linux/tee_remoteproc.h
> >>>> @@ -0,0 +1,112 @@
> >>>> +/* SPDX-License-Identifier: GPL-2.0-or-later */
> >>>> +/*
> >>>> + * Copyright(c) 2024 STMicroelectronics - All Rights Reserved
> >>>> + */
> >>>> +
> >>>> +#ifndef TEE_REMOTEPROC_H
> >>>> +#define TEE_REMOTEPROC_H
> >>>> +
> >>>> +#include <linux/tee_drv.h>
> >>>> +#include <linux/firmware.h>
> >>>> +#include <linux/remoteproc.h>
> >>>> +
> >>>> +struct rproc;
> >>>> +
> >>>> +/**
> >>>> + * struct tee_rproc - TEE remoteproc structure
> >>>> + * @node:		Reference in list
> >>>> + * @rproc:		Remoteproc reference
> >>>> + * @parent:		Parent device
> >>>> + * @rproc_id:		Identifier of the target firmware
> >>>> + * @session_id:		TEE session identifier
> >>>> + * @rsc_table:		Resource table virtual address.
> >>>> + */
> >>>> +struct tee_rproc {
> >>>> +	struct list_head node;
> >>>> +	struct rproc *rproc;
> >>>> +	struct device *parent;
> >>>> +	u32 rproc_id;
> >>>> +	u32 session_id;
> >>>> +	struct resource_table *rsc_table;
> >>>> +};
> >>>> +
> >>>> +#if IS_REACHABLE(CONFIG_TEE_REMOTEPROC)
> >>>> +
> >>>> +struct tee_rproc *tee_rproc_register(struct device *dev, struct rproc *rproc,
> >>>> +				     unsigned int rproc_id);
> >>>> +int tee_rproc_unregister(struct tee_rproc *trproc);
> >>>> +int tee_rproc_parse_fw(struct rproc *rproc, const struct firmware *fw);
> >>>> +int tee_rproc_load_fw(struct rproc *rproc, const struct firmware *fw);
> >>>> +struct resource_table *tee_rproc_get_loaded_rsc_table(struct rproc *rproc, size_t *table_sz);
> >>>> +struct resource_table *tee_rproc_find_loaded_rsc_table(struct rproc *rproc,
> >>>> +						       const struct firmware *fw);
> >>>> +int tee_rproc_start(struct rproc *rproc);
> >>>> +int tee_rproc_stop(struct rproc *rproc);
> >>>> +
> >>>> +#else
> >>>> +
> >>>> +static inline struct tee_rproc *tee_rproc_register(struct device *dev, struct rproc *rproc,
> >>>> +						   unsigned int rproc_id)
> >>>> +{
> >>>> +	return ERR_PTR(-ENODEV);
> >>>> +}
> >>>> +
> >>>> +static int tee_rproc_parse_fw(struct rproc *rproc, const struct firmware *fw)
> >>>> +{
> >>>> +	/* This shouldn't be possible */
> >>>> +	WARN_ON(1);
> >>>> +
> >>>> +	return 0;
> >>>> +}
> >>>> +
> >>>> +static inline int tee_rproc_unregister(struct tee_rproc *trproc)
> >>>> +{
> >>>> +	/* This shouldn't be possible */
> >>>> +	WARN_ON(1);
> >>>> +
> >>>> +	return 0;
> >>>> +}
> >>>> +
> >>>> +static inline int tee_rproc_load_fw(struct rproc *rproc,  const struct firmware *fw)
> >>>> +{
> >>>> +	/* This shouldn't be possible */
> >>>> +	WARN_ON(1);
> >>>> +
> >>>> +	return 0;
> >>>> +}
> >>>> +
> >>>> +static inline int tee_rproc_start(struct rproc *rproc)
> >>>> +{
> >>>> +	/* This shouldn't be possible */
> >>>> +	WARN_ON(1);
> >>>> +
> >>>> +	return 0;
> >>>> +}
> >>>> +
> >>>> +static inline int tee_rproc_stop(struct rproc *rproc)
> >>>> +{
> >>>> +	/* This shouldn't be possible */
> >>>> +	WARN_ON(1);
> >>>> +
> >>>> +	return 0;
> >>>> +}
> >>>> +
> >>>> +static inline struct resource_table *
> >>>> +tee_rproc_get_loaded_rsc_table(struct rproc *rproc, size_t *table_sz)
> >>>> +{
> >>>> +	/* This shouldn't be possible */
> >>>> +	WARN_ON(1);
> >>>> +
> >>>> +	return NULL;
> >>>> +}
> >>>> +
> >>>> +static inline struct resource_table *
> >>>> +tee_rproc_find_loaded_rsc_table(struct rproc *rproc, const struct firmware *fw)
> >>>> +{
> >>>> +	/* This shouldn't be possible */
> >>>> +	WARN_ON(1);
> >>>> +
> >>>> +	return NULL;
> >>>> +}
> >>>> +#endif /* CONFIG_TEE_REMOTEPROC */
> >>>> +#endif /* TEE_REMOTEPROC_H */
> >>>> -- 
> >>>> 2.25.1
> >>>>