diff mbox series

[v2,05/11] firewall: introduce stm32_firewall framework

Message ID 20230725164104.273965-6-gatien.chevallier@foss.st.com
State Superseded
Headers show
Series Introduce STM32 Firewall framework | expand

Commit Message

Gatien CHEVALLIER July 25, 2023, 4:40 p.m. UTC 
Introduce a STM32 firewall framework that offers to firewall consumers
different firewall services such as the ability to check their access
rights against their firewall controller(s).

The STM32 firewall framework offers a generic API for STM32 firewall
controllers that is defined in their drivers to best fit the
specificity of each firewall.

There are various types of firewalls:
-Peripheral firewalls that filter accesses to peripherals
-Memory firewalls that filter accesses to memories or memory regions
-No type for undefined type of firewall

Signed-off-by: Gatien Chevallier <gatien.chevallier@foss.st.com>
---

Changes in V2:
	- Support multiple entries for "feature-domains"
	  property. Change stm32_firewall_get_firewall()
	  to do so.
	- Better handle the device-tree parsing using
	  phandle+args APIs and phandle iterator.
	- Remove "resource firewall" type
	- Rephrase STM32_FIREWALL description in the bus
	  Kconfig and remove useless default value
	- Add missing EXPORT_SYMBOL_GPL
	- Remove useless stm32_firewall_get_id() API
	- Add a field for the name of the firewall entry
	  in the stm32_firewall_controller structure
	- Minor fixes on some traces level (err -> debug)
	- Fix licenses to GPL-2.0-only
	- Fix stm32_firewall_get_firewall() description
	- Rephrase some sentences to better emphasize this
	  is STM32-specific
	- Switch to list_for_each_entry() in
	  stm32_firewall_controller_unregister() as we only
	  expect one firewall controller instance per device.
	  The loop just breaks when found
	- Do not register the firewall controller if it is
	  already registered to the framework 

 MAINTAINERS                               |   5 +
 arch/arm64/Kconfig.platforms              |   1 +
 drivers/bus/Kconfig                       |   9 +
 drivers/bus/Makefile                      |   1 +
 drivers/bus/stm32_firewall.c              | 288 ++++++++++++++++++++++
 drivers/bus/stm32_firewall.h              |  83 +++++++
 include/linux/bus/stm32_firewall_device.h | 140 +++++++++++
 7 files changed, 527 insertions(+)
 create mode 100644 drivers/bus/stm32_firewall.c
 create mode 100644 drivers/bus/stm32_firewall.h
 create mode 100644 include/linux/bus/stm32_firewall_device.h

Comments

Simon Horman July 26, 2023, 10:19 a.m. UTC | #1 
On Tue, Jul 25, 2023 at 06:40:58PM +0200, Gatien Chevallier wrote:
> Introduce a STM32 firewall framework that offers to firewall consumers
> different firewall services such as the ability to check their access
> rights against their firewall controller(s).
> 
> The STM32 firewall framework offers a generic API for STM32 firewall
> controllers that is defined in their drivers to best fit the
> specificity of each firewall.
> 
> There are various types of firewalls:
> -Peripheral firewalls that filter accesses to peripherals
> -Memory firewalls that filter accesses to memories or memory regions
> -No type for undefined type of firewall
> 
> Signed-off-by: Gatien Chevallier <gatien.chevallier@foss.st.com>

...

> diff --git a/drivers/bus/stm32_firewall.c b/drivers/bus/stm32_firewall.c

...

> +int stm32_firewall_populate_bus(struct stm32_firewall_controller *firewall_controller)
> +{
> +	struct stm32_firewall *firewalls;
> +	struct device_node *child;
> +	struct device *parent;
> +	unsigned int i;
> +	int len;
> +	int err;
> +
> +	parent = firewall_controller->dev;
> +
> +	dev_dbg(parent, "Populating %s system bus\n", dev_name(firewall_controller->dev));
> +
> +	for_each_available_child_of_node(dev_of_node(parent), child) {
> +		/* The feature-domains property is mandatory for firewall bus devices */
> +		len = of_count_phandle_with_args(child, "feature-domains", "#feature-domain-cells");
> +		if (len <= 0)

Coccinelle says that, due to breaking out of a
for_each_available_child_of_node() loop, a call to of_node_put()
is needed here

> +			return -EINVAL;
> +
> +		firewalls = kcalloc(len, sizeof(*firewalls), GFP_KERNEL);
> +		if (!firewalls)

And here.

> +			return -ENOMEM;
> +
> +		err = stm32_firewall_get_firewall(child, firewalls, (unsigned int)len);
> +		if (err) {
> +			kfree(firewalls);

And here.

> +			return err;
> +		}
> +
> +		for (i = 0; i < len; i++) {
> +			if (firewall_controller->grant_access(firewall_controller,
> +							      firewalls[i].firewall_id)) {
> +				/*
> +				 * Peripheral access not allowed or not defined.
> +				 * Mark the node as populated so platform bus won't probe it
> +				 */
> +				of_node_set_flag(child, OF_POPULATED);
> +				dev_err(parent, "%s: Device driver will not be probed\n",
> +					child->full_name);
> +			}
> +		}
> +
> +		kfree(firewalls);
> +	}
> +
> +	return 0;
> +}
> +EXPORT_SYMBOL_GPL(stm32_firewall_populate_bus);

> diff --git a/drivers/bus/stm32_firewall.h b/drivers/bus/stm32_firewall.h

...

> +/**
> + * struct stm32_firewall_controller - Information on firewall controller supplying services
> + *
> + * @name			Name of the firewall controller

kernel-doc complains that name and the other fields of
struct stm32_firewall_controller are not documented.
I believe this is because a ':' is needed after the name of
the parameter (in this case 'name').

 * @name:			Name of the firewall controller

Likewise, elsewhere.

> + * @dev				Device reference of the firewall controller
> + * @mmio			Base address of the firewall controller
> + * @entry			List entry of the firewall controller list
> + * @type			Type of firewall
> + * @max_entries			Number of entries covered by the firewall
> + * @grant_access		Callback used to grant access for a device access against a
> + *				firewall controller
> + * @release_access		Callback used to release resources taken by a device when access was
> + *				granted
> + * @grant_memory_range_access	Callback used to grant access for a device to a given memory region
> + */
> +struct stm32_firewall_controller {
> +	const char *name;
> +	struct device *dev;
> +	void __iomem *mmio;
> +	struct list_head entry;
> +	unsigned int type;
> +	unsigned int max_entries;
> +
> +	int (*grant_access)(struct stm32_firewall_controller *ctrl, u32 id);
> +	void (*release_access)(struct stm32_firewall_controller *ctrl, u32 id);
> +	int (*grant_memory_range_access)(struct stm32_firewall_controller *ctrl, phys_addr_t paddr,
> +					 size_t size);
> +};
> +
> +/**
> + * int stm32_firewall_controller_register - Register a firewall controller to the STM32 firewall

kernel-doc seems unhappy about the presence of 'int' on this line.

 * stm32_firewall_controller_register - Register a firewall controller to the STM32 firewall

Likewise, elsewhere.

> + *					    framework
> + * @firewall_controller		Firewall controller to register
> + *
> + * Returns 0 in case of success or -ENODEV if no controller was given.
> + */
> +int stm32_firewall_controller_register(struct stm32_firewall_controller *firewall_controller);

...

> diff --git a/include/linux/bus/stm32_firewall_device.h b/include/linux/bus/stm32_firewall_device.h
> new file mode 100644
> index 000000000000..9bdc4060154c
> --- /dev/null
> +++ b/include/linux/bus/stm32_firewall_device.h
> @@ -0,0 +1,140 @@
> +/* SPDX-License-Identifier: GPL-2.0-only */
> +/*
> + * Copyright (C) 2023, STMicroelectronics - All Rights Reserved
> + */
> +
> +#ifndef STM32_FIREWALL_DEVICE_H
> +#define STM32_FIREWALL_DEVICE_H
> +
> +#include <linux/of.h>
> +#include <linux/platform_device.h>
> +#include <linux/types.h>
> +
> +#define STM32_FIREWALL_MAX_EXTRA_ARGS		5
> +
> +/* Opaque reference to stm32_firewall_controller */
> +struct stm32_firewall_controller;
> +
> +/**
> + * stm32_firewall - Information on a device's firewall. Each device can have more than one firewall.

kernel-doc seems unhappy about the absence of struct on this line.

 * struct stm32_firewall - Information on a device's firewall. Each device can have more than one firewall.

> + *
> + * @firewall_ctrl		Pointer referencing a firewall controller of the device. It is
> + *				opaque so a device cannot manipulate the controller's ops or access
> + *				the controller's data
> + * @extra_args			Extra arguments that are implementation dependent
> + * @entry			Name of the firewall entry
> + * @extra_args_size		Number of extra arguments
> + * @firewall_id			Firewall ID associated the device for this firewall controller
> + */
> +struct stm32_firewall {
> +	struct stm32_firewall_controller *firewall_ctrl;
> +	u32 extra_args[STM32_FIREWALL_MAX_EXTRA_ARGS];
> +	const char *entry;
> +	size_t extra_args_size;
> +	u32 firewall_id;
> +};

...
Simon Horman July 26, 2023, 10:22 a.m. UTC | #2 
On Tue, Jul 25, 2023 at 06:40:58PM +0200, Gatien Chevallier wrote:

...

> diff --git a/drivers/bus/stm32_firewall.c b/drivers/bus/stm32_firewall.c

...

> +int stm32_firewall_controller_register(struct stm32_firewall_controller *firewall_controller)
> +{
> +	struct stm32_firewall_controller *ctrl;
> +
> +	pr_info("Registering %s firewall controller\n", firewall_controller->name);
> +
> +	if (!firewall_controller)
> +		return -ENODEV;

HI Gatien,

Sorry, one more on this patch, that I missed before sending my previous
email.

firewall_controller is checked for NULL here.
But it is already dereferenced on the line above the check.

Flagged by Smatch.

...
Gatien CHEVALLIER July 26, 2023, 10:38 a.m. UTC | #3 
On 7/26/23 12:19, Simon Horman wrote:
> On Tue, Jul 25, 2023 at 06:40:58PM +0200, Gatien Chevallier wrote:
>> Introduce a STM32 firewall framework that offers to firewall consumers
>> different firewall services such as the ability to check their access
>> rights against their firewall controller(s).
>>
>> The STM32 firewall framework offers a generic API for STM32 firewall
>> controllers that is defined in their drivers to best fit the
>> specificity of each firewall.
>>
>> There are various types of firewalls:
>> -Peripheral firewalls that filter accesses to peripherals
>> -Memory firewalls that filter accesses to memories or memory regions
>> -No type for undefined type of firewall
>>
>> Signed-off-by: Gatien Chevallier <gatien.chevallier@foss.st.com>
> 
> ...
> 
>> diff --git a/drivers/bus/stm32_firewall.c b/drivers/bus/stm32_firewall.c
> 
> ...
> 
>> +int stm32_firewall_populate_bus(struct stm32_firewall_controller *firewall_controller)
>> +{
>> +	struct stm32_firewall *firewalls;
>> +	struct device_node *child;
>> +	struct device *parent;
>> +	unsigned int i;
>> +	int len;
>> +	int err;
>> +
>> +	parent = firewall_controller->dev;
>> +
>> +	dev_dbg(parent, "Populating %s system bus\n", dev_name(firewall_controller->dev));
>> +
>> +	for_each_available_child_of_node(dev_of_node(parent), child) {
>> +		/* The feature-domains property is mandatory for firewall bus devices */
>> +		len = of_count_phandle_with_args(child, "feature-domains", "#feature-domain-cells");
>> +		if (len <= 0)
> 
> Coccinelle says that, due to breaking out of a
> for_each_available_child_of_node() loop, a call to of_node_put()
> is needed here
> 

Hi Simon,

Thank you, I already sent a V3 correcting the patch ordering issue. I
will implement this for V4.

>> +			return -EINVAL;
>> +
>> +		firewalls = kcalloc(len, sizeof(*firewalls), GFP_KERNEL);
>> +		if (!firewalls)
> 
> And here.
> 

ditto

>> +			return -ENOMEM;
>> +
>> +		err = stm32_firewall_get_firewall(child, firewalls, (unsigned int)len);
>> +		if (err) {
>> +			kfree(firewalls);
> 
> And here.
> 

ditto

>> +			return err;
>> +		}
>> +
>> +		for (i = 0; i < len; i++) {
>> +			if (firewall_controller->grant_access(firewall_controller,
>> +							      firewalls[i].firewall_id)) {
>> +				/*
>> +				 * Peripheral access not allowed or not defined.
>> +				 * Mark the node as populated so platform bus won't probe it
>> +				 */
>> +				of_node_set_flag(child, OF_POPULATED);
>> +				dev_err(parent, "%s: Device driver will not be probed\n",
>> +					child->full_name);
>> +			}
>> +		}
>> +
>> +		kfree(firewalls);
>> +	}
>> +
>> +	return 0;
>> +}
>> +EXPORT_SYMBOL_GPL(stm32_firewall_populate_bus);
> 
>> diff --git a/drivers/bus/stm32_firewall.h b/drivers/bus/stm32_firewall.h
> 
> ...
> 
>> +/**
>> + * struct stm32_firewall_controller - Information on firewall controller supplying services
>> + *
>> + * @name			Name of the firewall controller
> 
> kernel-doc complains that name and the other fields of
> struct stm32_firewall_controller are not documented.
> I believe this is because a ':' is needed after the name of
> the parameter (in this case 'name').
> 
>   * @name:			Name of the firewall controller
> 
> Likewise, elsewhere.
> 

I will implement it in V4, thank you.

>> + * @dev				Device reference of the firewall controller
>> + * @mmio			Base address of the firewall controller
>> + * @entry			List entry of the firewall controller list
>> + * @type			Type of firewall
>> + * @max_entries			Number of entries covered by the firewall
>> + * @grant_access		Callback used to grant access for a device access against a
>> + *				firewall controller
>> + * @release_access		Callback used to release resources taken by a device when access was
>> + *				granted
>> + * @grant_memory_range_access	Callback used to grant access for a device to a given memory region
>> + */
>> +struct stm32_firewall_controller {
>> +	const char *name;
>> +	struct device *dev;
>> +	void __iomem *mmio;
>> +	struct list_head entry;
>> +	unsigned int type;
>> +	unsigned int max_entries;
>> +
>> +	int (*grant_access)(struct stm32_firewall_controller *ctrl, u32 id);
>> +	void (*release_access)(struct stm32_firewall_controller *ctrl, u32 id);
>> +	int (*grant_memory_range_access)(struct stm32_firewall_controller *ctrl, phys_addr_t paddr,
>> +					 size_t size);
>> +};
>> +
>> +/**
>> + * int stm32_firewall_controller_register - Register a firewall controller to the STM32 firewall
> 
> kernel-doc seems unhappy about the presence of 'int' on this line.
> 
>   * stm32_firewall_controller_register - Register a firewall controller to the STM32 firewall
> 
> Likewise, elsewhere.
> 

Yes, I will remove the type in V4.

>> + *					    framework
>> + * @firewall_controller		Firewall controller to register
>> + *
>> + * Returns 0 in case of success or -ENODEV if no controller was given.
>> + */
>> +int stm32_firewall_controller_register(struct stm32_firewall_controller *firewall_controller);
> 
> ...
> 
>> diff --git a/include/linux/bus/stm32_firewall_device.h b/include/linux/bus/stm32_firewall_device.h
>> new file mode 100644
>> index 000000000000..9bdc4060154c
>> --- /dev/null
>> +++ b/include/linux/bus/stm32_firewall_device.h
>> @@ -0,0 +1,140 @@
>> +/* SPDX-License-Identifier: GPL-2.0-only */
>> +/*
>> + * Copyright (C) 2023, STMicroelectronics - All Rights Reserved
>> + */
>> +
>> +#ifndef STM32_FIREWALL_DEVICE_H
>> +#define STM32_FIREWALL_DEVICE_H
>> +
>> +#include <linux/of.h>
>> +#include <linux/platform_device.h>
>> +#include <linux/types.h>
>> +
>> +#define STM32_FIREWALL_MAX_EXTRA_ARGS		5
>> +
>> +/* Opaque reference to stm32_firewall_controller */
>> +struct stm32_firewall_controller;
>> +
>> +/**
>> + * stm32_firewall - Information on a device's firewall. Each device can have more than one firewall.
> 
> kernel-doc seems unhappy about the absence of struct on this line.
> 
>   * struct stm32_firewall - Information on a device's firewall. Each device can have more than one firewall.
> 

Yes, I will add the struct in V4.

>> + *
>> + * @firewall_ctrl		Pointer referencing a firewall controller of the device. It is
>> + *				opaque so a device cannot manipulate the controller's ops or access
>> + *				the controller's data
>> + * @extra_args			Extra arguments that are implementation dependent
>> + * @entry			Name of the firewall entry
>> + * @extra_args_size		Number of extra arguments
>> + * @firewall_id			Firewall ID associated the device for this firewall controller
>> + */
>> +struct stm32_firewall {
>> +	struct stm32_firewall_controller *firewall_ctrl;
>> +	u32 extra_args[STM32_FIREWALL_MAX_EXTRA_ARGS];
>> +	const char *entry;
>> +	size_t extra_args_size;
>> +	u32 firewall_id;
>> +};
> 
> ...
> 
Best regards,
Gatien
Gatien CHEVALLIER July 26, 2023, 10:39 a.m. UTC | #4 
On 7/26/23 12:22, Simon Horman wrote:
> On Tue, Jul 25, 2023 at 06:40:58PM +0200, Gatien Chevallier wrote:
> 
> ...
> 
>> diff --git a/drivers/bus/stm32_firewall.c b/drivers/bus/stm32_firewall.c
> 
> ...
> 
>> +int stm32_firewall_controller_register(struct stm32_firewall_controller *firewall_controller)
>> +{
>> +	struct stm32_firewall_controller *ctrl;
>> +
>> +	pr_info("Registering %s firewall controller\n", firewall_controller->name);
>> +
>> +	if (!firewall_controller)
>> +		return -ENODEV;
> 
> HI Gatien,
> 
> Sorry, one more on this patch, that I missed before sending my previous
> email.
> 
> firewall_controller is checked for NULL here.
> But it is already dereferenced on the line above the check.
> 
> Flagged by Smatch.
> 
> ...

Indeed, thank you. I will change this for V4

Best regards,
Gatien
Simon Horman July 26, 2023, 11:39 a.m. UTC | #5 
On Wed, Jul 26, 2023 at 12:38:00PM +0200, Gatien CHEVALLIER wrote:
> 
> 
> On 7/26/23 12:19, Simon Horman wrote:
> > On Tue, Jul 25, 2023 at 06:40:58PM +0200, Gatien Chevallier wrote:
> > > Introduce a STM32 firewall framework that offers to firewall consumers
> > > different firewall services such as the ability to check their access
> > > rights against their firewall controller(s).
> > > 
> > > The STM32 firewall framework offers a generic API for STM32 firewall
> > > controllers that is defined in their drivers to best fit the
> > > specificity of each firewall.
> > > 
> > > There are various types of firewalls:
> > > -Peripheral firewalls that filter accesses to peripherals
> > > -Memory firewalls that filter accesses to memories or memory regions
> > > -No type for undefined type of firewall
> > > 
> > > Signed-off-by: Gatien Chevallier <gatien.chevallier@foss.st.com>
> > 
> > ...
> > 
> > > diff --git a/drivers/bus/stm32_firewall.c b/drivers/bus/stm32_firewall.c
> > 
> > ...
> > 
> > > +int stm32_firewall_populate_bus(struct stm32_firewall_controller *firewall_controller)
> > > +{
> > > +	struct stm32_firewall *firewalls;
> > > +	struct device_node *child;
> > > +	struct device *parent;
> > > +	unsigned int i;
> > > +	int len;
> > > +	int err;
> > > +
> > > +	parent = firewall_controller->dev;
> > > +
> > > +	dev_dbg(parent, "Populating %s system bus\n", dev_name(firewall_controller->dev));
> > > +
> > > +	for_each_available_child_of_node(dev_of_node(parent), child) {
> > > +		/* The feature-domains property is mandatory for firewall bus devices */
> > > +		len = of_count_phandle_with_args(child, "feature-domains", "#feature-domain-cells");
> > > +		if (len <= 0)
> > 
> > Coccinelle says that, due to breaking out of a
> > for_each_available_child_of_node() loop, a call to of_node_put()
> > is needed here
> > 
> 
> Hi Simon,
> 
> Thank you, I already sent a V3 correcting the patch ordering issue. I
> will implement this for V4.

Hi Gatien,

Thanks and sorry for not noticing v3 - I think it arrived while
I was in the middle of reviewing v2.
diff mbox series

Patch

diff --git a/MAINTAINERS b/MAINTAINERS
index d516295978a4..17559ed17a11 100644
--- a/MAINTAINERS
+++ b/MAINTAINERS
@@ -20137,6 +20137,11 @@  T:	git git://linuxtv.org/media_tree.git
 F:	Documentation/devicetree/bindings/media/i2c/st,st-mipid02.yaml
 F:	drivers/media/i2c/st-mipid02.c
 
+ST STM32 FIREWALL
+M:	Gatien Chevallier <gatien.chevallier@foss.st.com>
+S:	Maintained
+F:	drivers/bus/stm32_firewall.c
+
 ST STM32 I2C/SMBUS DRIVER
 M:	Pierre-Yves MORDRET <pierre-yves.mordret@foss.st.com>
 M:	Alain Volmat <alain.volmat@foss.st.com>
diff --git a/arch/arm64/Kconfig.platforms b/arch/arm64/Kconfig.platforms
index 6069120199bb..5a46e90f1e4e 100644
--- a/arch/arm64/Kconfig.platforms
+++ b/arch/arm64/Kconfig.platforms
@@ -293,6 +293,7 @@  config ARCH_STM32
 	select ARM_SMC_MBOX
 	select ARM_SCMI_PROTOCOL
 	select COMMON_CLK_SCMI
+	select STM32_FIREWALL
 	help
 	  This enables support for ARMv8 based STMicroelectronics
 	  STM32 family, including:
diff --git a/drivers/bus/Kconfig b/drivers/bus/Kconfig
index fcfa280df98a..7ac904363a28 100644
--- a/drivers/bus/Kconfig
+++ b/drivers/bus/Kconfig
@@ -163,6 +163,15 @@  config QCOM_SSC_BLOCK_BUS
 	  i2c/spi/uart controllers, a hexagon core, and a clock controller
 	  which provides clocks for the above.
 
+config STM32_FIREWALL
+	bool "STM32 Firewall framework"
+	depends on ARCH_STM32 || COMPILE_TEST
+	help
+	  Say y to enable STM32 firewall framework and its services. Firewall
+	  controllers will be able to register to the framework. Access for
+	  hardware resources linked to a firewall controller can be requested
+	  through this STM32 framework.
+
 config SUN50I_DE2_BUS
 	bool "Allwinner A64 DE2 Bus Driver"
 	  default ARM64
diff --git a/drivers/bus/Makefile b/drivers/bus/Makefile
index d90eed189a65..fc0511450ec2 100644
--- a/drivers/bus/Makefile
+++ b/drivers/bus/Makefile
@@ -26,6 +26,7 @@  obj-$(CONFIG_OMAP_INTERCONNECT)	+= omap_l3_smx.o omap_l3_noc.o
 obj-$(CONFIG_OMAP_OCP2SCP)	+= omap-ocp2scp.o
 obj-$(CONFIG_QCOM_EBI2)		+= qcom-ebi2.o
 obj-$(CONFIG_QCOM_SSC_BLOCK_BUS)	+= qcom-ssc-block-bus.o
+obj-$(CONFIG_STM32_FIREWALL)	+= stm32_firewall.o
 obj-$(CONFIG_SUN50I_DE2_BUS)	+= sun50i-de2.o
 obj-$(CONFIG_SUNXI_RSB)		+= sunxi-rsb.o
 obj-$(CONFIG_OF)		+= simple-pm-bus.o
diff --git a/drivers/bus/stm32_firewall.c b/drivers/bus/stm32_firewall.c
new file mode 100644
index 000000000000..4a8e44b732b1
--- /dev/null
+++ b/drivers/bus/stm32_firewall.c
@@ -0,0 +1,288 @@ 
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * Copyright (C) 2023, STMicroelectronics - All Rights Reserved
+ */
+
+#include <linux/bitfield.h>
+#include <linux/bits.h>
+#include <linux/bus/stm32_firewall_device.h>
+#include <linux/device.h>
+#include <linux/err.h>
+#include <linux/init.h>
+#include <linux/io.h>
+#include <linux/kernel.h>
+#include <linux/module.h>
+#include <linux/of.h>
+#include <linux/of_platform.h>
+#include <linux/platform_device.h>
+#include <linux/types.h>
+#include <linux/slab.h>
+
+#include "stm32_firewall.h"
+
+/* Corresponds to STM32_FIREWALL_MAX_EXTRA_ARGS + firewall ID */
+#define STM32_FIREWALL_MAX_ARGS		(STM32_FIREWALL_MAX_EXTRA_ARGS + 1)
+
+static LIST_HEAD(firewall_controller_list);
+static DEFINE_MUTEX(firewall_controller_list_lock);
+
+/* Firewall device API */
+
+int stm32_firewall_get_firewall(struct device_node *np, struct stm32_firewall *firewall,
+				unsigned int nb_firewall)
+{
+	struct stm32_firewall_controller *ctrl;
+	struct of_phandle_iterator it;
+	unsigned int i, j = 0;
+	int err;
+
+	if (!firewall || !nb_firewall)
+		return -EINVAL;
+
+	/* Parse property with phandle parsed out */
+	of_for_each_phandle(&it, err, np, "feature-domains", "#feature-domain-cells", 0) {
+		struct of_phandle_args provider_args;
+		struct device_node *provider = it.node;
+		const char *fw_entry;
+		bool match = false;
+
+		if (err) {
+			pr_err("Unable to get feature-domains property for node %s\n, err: %d",
+			       np->full_name, err);
+			of_node_put(provider);
+			return err;
+		}
+
+		if (j > nb_firewall) {
+			pr_err("Too many firewall controllers");
+			of_node_put(provider);
+			return -EINVAL;
+		}
+
+		provider_args.args_count = of_phandle_iterator_args(&it, provider_args.args,
+								    STM32_FIREWALL_MAX_ARGS);
+
+		/* Check if the parsed phandle corresponds to a registered firewall controller */
+		mutex_lock(&firewall_controller_list_lock);
+		list_for_each_entry(ctrl, &firewall_controller_list, entry) {
+			if (ctrl->dev->of_node->phandle == it.phandle) {
+				match = true;
+				firewall[j].firewall_ctrl = ctrl;
+				break;
+			}
+		}
+		mutex_unlock(&firewall_controller_list_lock);
+
+		if (!match) {
+			firewall[j].firewall_ctrl = NULL;
+			pr_err("No firewall controller registered for %s\n", np->full_name);
+			of_node_put(provider);
+			return -ENODEV;
+		}
+
+		err = of_property_read_string_index(np, "feature-domain-names", j, &fw_entry);
+		if (err == 0)
+			firewall[j].entry = fw_entry;
+
+		/* Handle the case when there are no arguments given along with the phandle */
+		if (provider_args.args_count < 0 ||
+		    provider_args.args_count > STM32_FIREWALL_MAX_ARGS) {
+			of_node_put(provider);
+			return -EINVAL;
+		} else if (provider_args.args_count == 0) {
+			firewall[j].extra_args_size = 0;
+			firewall[j].firewall_id = U32_MAX;
+			j++;
+			continue;
+		}
+
+		/* The firewall ID is always the first argument */
+		firewall[j].firewall_id = provider_args.args[0];
+
+		/* Extra args start at the third argument */
+		for (i = 0; i < provider_args.args_count; i++)
+			firewall[j].extra_args[i] = provider_args.args[i + 1];
+
+		/* Remove the firewall ID arg that is not an extra argument */
+		firewall[j].extra_args_size = provider_args.args_count - 1;
+
+		j++;
+	}
+
+	return 0;
+}
+EXPORT_SYMBOL_GPL(stm32_firewall_get_firewall);
+
+int stm32_firewall_grant_access(struct stm32_firewall *firewall)
+{
+	struct stm32_firewall_controller *firewall_controller;
+
+	if (!firewall || firewall->firewall_id == U32_MAX)
+		return -EINVAL;
+
+	firewall_controller = firewall->firewall_ctrl;
+
+	if (!firewall_controller)
+		return -ENODEV;
+
+	return firewall_controller->grant_access(firewall_controller, firewall->firewall_id);
+}
+EXPORT_SYMBOL_GPL(stm32_firewall_grant_access);
+
+int stm32_firewall_grant_access_by_id(struct stm32_firewall *firewall, u32 subsystem_id)
+{
+	struct stm32_firewall_controller *firewall_controller;
+
+	if (!firewall || subsystem_id == U32_MAX || firewall->firewall_id == U32_MAX)
+		return -EINVAL;
+
+	firewall_controller = firewall->firewall_ctrl;
+
+	if (!firewall_controller)
+		return -ENODEV;
+
+	return firewall_controller->grant_access(firewall_controller, subsystem_id);
+}
+EXPORT_SYMBOL_GPL(stm32_firewall_grant_access_by_id);
+
+void stm32_firewall_release_access(struct stm32_firewall *firewall)
+{
+	struct stm32_firewall_controller *firewall_controller;
+
+	if (!firewall || firewall->firewall_id == U32_MAX) {
+		pr_debug("Incorrect arguments when releasing a firewall access\n");
+		return;
+	}
+
+	firewall_controller = firewall->firewall_ctrl;
+
+	if (!firewall_controller) {
+		pr_debug("No firewall controller to release\n");
+		return;
+	}
+
+	firewall_controller->release_access(firewall_controller, firewall->firewall_id);
+}
+EXPORT_SYMBOL_GPL(stm32_firewall_release_access);
+
+void stm32_firewall_release_access_by_id(struct stm32_firewall *firewall, u32 subsystem_id)
+{
+	struct stm32_firewall_controller *firewall_controller;
+
+	if (!firewall || subsystem_id == U32_MAX || firewall->firewall_id == U32_MAX) {
+		pr_debug("Incorrect arguments when releasing a firewall access");
+		return;
+	}
+
+	firewall_controller = firewall->firewall_ctrl;
+
+	if (!firewall_controller) {
+		pr_debug("No firewall controller to release");
+		return;
+	}
+
+	firewall_controller->release_access(firewall_controller, subsystem_id);
+}
+EXPORT_SYMBOL_GPL(stm32_firewall_release_access_by_id);
+
+/* Firewall controller API */
+
+int stm32_firewall_controller_register(struct stm32_firewall_controller *firewall_controller)
+{
+	struct stm32_firewall_controller *ctrl;
+
+	pr_info("Registering %s firewall controller\n", firewall_controller->name);
+
+	if (!firewall_controller)
+		return -ENODEV;
+
+	mutex_lock(&firewall_controller_list_lock);
+	list_for_each_entry(ctrl, &firewall_controller_list, entry) {
+		if (ctrl == firewall_controller) {
+			pr_debug("%s firewall controller already registered\n",
+				 firewall_controller->name);
+			mutex_unlock(&firewall_controller_list_lock);
+			return 0;
+		}
+	}
+	list_add_tail(&firewall_controller->entry, &firewall_controller_list);
+	mutex_unlock(&firewall_controller_list_lock);
+
+	return 0;
+}
+EXPORT_SYMBOL_GPL(stm32_firewall_controller_register);
+
+void stm32_firewall_controller_unregister(struct stm32_firewall_controller *firewall_controller)
+{
+	struct stm32_firewall_controller *ctrl;
+	bool controller_removed = false;
+
+	if (!firewall_controller) {
+		pr_debug("Null reference while unregistering firewall controller\n");
+		return;
+	}
+
+	mutex_lock(&firewall_controller_list_lock);
+	list_for_each_entry(ctrl, &firewall_controller_list, entry) {
+		if (ctrl == firewall_controller) {
+			controller_removed = true;
+			list_del_init(&ctrl->entry);
+			break;
+		}
+	}
+	mutex_unlock(&firewall_controller_list_lock);
+
+	if (!controller_removed)
+		pr_debug("There was no firewall controller named %s to unregister\n",
+			 firewall_controller->name);
+}
+EXPORT_SYMBOL_GPL(stm32_firewall_controller_unregister);
+
+int stm32_firewall_populate_bus(struct stm32_firewall_controller *firewall_controller)
+{
+	struct stm32_firewall *firewalls;
+	struct device_node *child;
+	struct device *parent;
+	unsigned int i;
+	int len;
+	int err;
+
+	parent = firewall_controller->dev;
+
+	dev_dbg(parent, "Populating %s system bus\n", dev_name(firewall_controller->dev));
+
+	for_each_available_child_of_node(dev_of_node(parent), child) {
+		/* The feature-domains property is mandatory for firewall bus devices */
+		len = of_count_phandle_with_args(child, "feature-domains", "#feature-domain-cells");
+		if (len <= 0)
+			return -EINVAL;
+
+		firewalls = kcalloc(len, sizeof(*firewalls), GFP_KERNEL);
+		if (!firewalls)
+			return -ENOMEM;
+
+		err = stm32_firewall_get_firewall(child, firewalls, (unsigned int)len);
+		if (err) {
+			kfree(firewalls);
+			return err;
+		}
+
+		for (i = 0; i < len; i++) {
+			if (firewall_controller->grant_access(firewall_controller,
+							      firewalls[i].firewall_id)) {
+				/*
+				 * Peripheral access not allowed or not defined.
+				 * Mark the node as populated so platform bus won't probe it
+				 */
+				of_node_set_flag(child, OF_POPULATED);
+				dev_err(parent, "%s: Device driver will not be probed\n",
+					child->full_name);
+			}
+		}
+
+		kfree(firewalls);
+	}
+
+	return 0;
+}
+EXPORT_SYMBOL_GPL(stm32_firewall_populate_bus);
diff --git a/drivers/bus/stm32_firewall.h b/drivers/bus/stm32_firewall.h
new file mode 100644
index 000000000000..eed089a0acc0
--- /dev/null
+++ b/drivers/bus/stm32_firewall.h
@@ -0,0 +1,83 @@ 
+/* SPDX-License-Identifier: GPL-2.0-only */
+/*
+ * Copyright (C) 2023, STMicroelectronics - All Rights Reserved
+ */
+
+#ifndef _STM32_FIREWALL_H
+#define _STM32_FIREWALL_H
+
+#include <linux/kernel.h>
+#include <linux/list.h>
+#include <linux/of.h>
+#include <linux/platform_device.h>
+#include <linux/types.h>
+
+/**
+ * STM32_PERIPHERAL_FIREWALL:		This type of firewall protects peripherals
+ * STM32_MEMORY_FIREWALL:		This type of firewall protects memories/subsets of memory
+ *					zones
+ * STM32_NOTYPE_FIREWALL:		Undefined firewall type
+ */
+
+#define STM32_PERIPHERAL_FIREWALL	BIT(1)
+#define STM32_MEMORY_FIREWALL		BIT(2)
+#define STM32_NOTYPE_FIREWALL		BIT(3)
+
+/**
+ * struct stm32_firewall_controller - Information on firewall controller supplying services
+ *
+ * @name			Name of the firewall controller
+ * @dev				Device reference of the firewall controller
+ * @mmio			Base address of the firewall controller
+ * @entry			List entry of the firewall controller list
+ * @type			Type of firewall
+ * @max_entries			Number of entries covered by the firewall
+ * @grant_access		Callback used to grant access for a device access against a
+ *				firewall controller
+ * @release_access		Callback used to release resources taken by a device when access was
+ *				granted
+ * @grant_memory_range_access	Callback used to grant access for a device to a given memory region
+ */
+struct stm32_firewall_controller {
+	const char *name;
+	struct device *dev;
+	void __iomem *mmio;
+	struct list_head entry;
+	unsigned int type;
+	unsigned int max_entries;
+
+	int (*grant_access)(struct stm32_firewall_controller *ctrl, u32 id);
+	void (*release_access)(struct stm32_firewall_controller *ctrl, u32 id);
+	int (*grant_memory_range_access)(struct stm32_firewall_controller *ctrl, phys_addr_t paddr,
+					 size_t size);
+};
+
+/**
+ * int stm32_firewall_controller_register - Register a firewall controller to the STM32 firewall
+ *					    framework
+ * @firewall_controller		Firewall controller to register
+ *
+ * Returns 0 in case of success or -ENODEV if no controller was given.
+ */
+int stm32_firewall_controller_register(struct stm32_firewall_controller *firewall_controller);
+
+/**
+ * int stm32_firewall_controller_unregister - Unregister a firewall controller from the STM32
+ *					      firewall framework
+ * @firewall_controller		Firewall controller to unregister
+ */
+void stm32_firewall_controller_unregister(struct stm32_firewall_controller *firewall_controller);
+
+/**
+ * stm32_firewall_populate_bus - Populate device tree nodes that have a correct firewall
+ *				 configuration. This is used at boot-time only, as a sanity check
+ *				 between device tree and firewalls hardware configurations to
+ *				 prevent a kernel crash when a device driver is not granted access
+ *
+ * @firewall_controller		Firewall controller which nodes will be populated or not
+ *
+ * Returns 0 in case of success or appropriate errno code if error occurred.
+ */
+int stm32_firewall_populate_bus(struct stm32_firewall_controller *firewall_controller);
+
+#endif /* _STM32_FIREWALL_H */
diff --git a/include/linux/bus/stm32_firewall_device.h b/include/linux/bus/stm32_firewall_device.h
new file mode 100644
index 000000000000..9bdc4060154c
--- /dev/null
+++ b/include/linux/bus/stm32_firewall_device.h
@@ -0,0 +1,140 @@ 
+/* SPDX-License-Identifier: GPL-2.0-only */
+/*
+ * Copyright (C) 2023, STMicroelectronics - All Rights Reserved
+ */
+
+#ifndef STM32_FIREWALL_DEVICE_H
+#define STM32_FIREWALL_DEVICE_H
+
+#include <linux/of.h>
+#include <linux/platform_device.h>
+#include <linux/types.h>
+
+#define STM32_FIREWALL_MAX_EXTRA_ARGS		5
+
+/* Opaque reference to stm32_firewall_controller */
+struct stm32_firewall_controller;
+
+/**
+ * stm32_firewall - Information on a device's firewall. Each device can have more than one firewall.
+ *
+ * @firewall_ctrl		Pointer referencing a firewall controller of the device. It is
+ *				opaque so a device cannot manipulate the controller's ops or access
+ *				the controller's data
+ * @extra_args			Extra arguments that are implementation dependent
+ * @entry			Name of the firewall entry
+ * @extra_args_size		Number of extra arguments
+ * @firewall_id			Firewall ID associated the device for this firewall controller
+ */
+struct stm32_firewall {
+	struct stm32_firewall_controller *firewall_ctrl;
+	u32 extra_args[STM32_FIREWALL_MAX_EXTRA_ARGS];
+	const char *entry;
+	size_t extra_args_size;
+	u32 firewall_id;
+};
+
+#if IS_ENABLED(CONFIG_STM32_FIREWALL)
+/**
+ * stm32_firewall_get_firewall - Get the firewall(s) associated to given device.
+ *				 The firewall controller reference is always the first argument
+ *				 of each of the feature-domains property entries.
+ *				 The firewall ID is always the second argument of each of the
+ *				 feature-domains property entries.
+ *				 If there's no argument linked to the phandle, then the firewall ID
+ *				 field is set to U32_MAX, which is an invalid ID.
+ *
+ * @np				Device node to parse
+ * @firewall			Array of firewall references
+ * @nb_firewall			Number of firewall references to get. Must be at least 1.
+ *
+ * Returns 0 on success, -ENODEV if there's no match with a firewall controller or appropriate errno
+ * code if error occurred.
+ */
+int stm32_firewall_get_firewall(struct device_node *np, struct stm32_firewall *firewall,
+				unsigned int nb_firewall);
+
+/**
+ * stm32_firewall_grant_access - Request firewall access rights and grant access.
+ *
+ * @firewall			Firewall reference containing the ID to check against its firewall
+ *				controller
+ *
+ * Returns 0 if access is granted, -EACCES if access is denied, -ENODEV if firewall is null or
+ * appropriate errno code if error occurred
+ */
+int stm32_firewall_grant_access(struct stm32_firewall *firewall);
+
+/**
+ * stm32_firewall_release_access - Release access granted from a call to
+ *				   stm32_firewall_grant_access().
+ *
+ * @firewall			Firewall reference containing the ID to check against its firewall
+ *				controller
+ */
+void stm32_firewall_release_access(struct stm32_firewall *firewall);
+
+/**
+ * stm32_firewall_grant_access_by_id - Request firewall access rights of a given device
+ *				       based on a specific firewall ID
+ *
+ * Warnings:
+ * There is no way to ensure that the given ID will correspond to the firewall referenced in the
+ * device node if the ID did not come from stm32_firewall_get_firewall(). In that case, this
+ * function must be used with caution.
+ * This function should be used for subsystem resources that do not have the same firewall ID
+ * as their parent.
+ * U32_MAX is an invalid ID.
+ *
+ * @firewall			Firewall reference containing the firewall controller
+ * @subsystem_id		Firewall ID of the subsystem resource
+ *
+ * Returns 0 if access is granted, -EACCES if access is denied, -ENODEV if firewall is null or
+ * appropriate errno code if error occurred
+ */
+int stm32_firewall_grant_access_by_id(struct stm32_firewall *firewall, u32 subsystem_id);
+
+/**
+ * stm32_firewall_release_access_by_id - Release access granted from a call to
+ *					 stm32_firewall_grant_access_by_id().
+ *
+ * Warnings:
+ * There is no way to ensure that the given ID will correspond to the firewall referenced in the
+ * device node if the ID did not come from stm32_firewall_get_firewall(). In that case, this
+ * function must be used with caution.
+ * This function should be used for subsystem resources that do not have the same firewall ID
+ * as their parent.
+ * U32_MAX is an invalid ID.
+ *
+ * @firewall			Firewall reference containing the firewall controller
+ * @subsystem_id		Firewall ID of the subsystem resource
+ */
+void stm32_firewall_release_access_by_id(struct stm32_firewall *firewall, u32 subsystem_id);
+
+#else /* CONFIG_STM32_FIREWALL */
+
+int stm32_firewall_get_firewall(struct device_node *np, struct stm32_firewall *firewall)
+{
+	return -ENODEV;
+}
+
+int stm32_firewall_grant_access(struct stm32_firewall *firewall)
+{
+	return -ENODEV;
+}
+
+void stm32_firewall_release_access(struct stm32_firewall *firewall)
+{
+}
+
+int stm32_firewall_grant_access_by_id(struct stm32_firewall *firewall, u32 subsystem_id)
+{
+	return -ENODEV;
+}
+
+void stm32_firewall_release_access_by_id(struct stm32_firewall *firewall, u32 subsystem_id)
+{
+}
+
+#endif /* CONFIG_STM32_FIREWALL */
+#endif /* STM32_FIREWALL_DEVICE_H */