[v2,05/11] firewall: introduce stm32_firewall framework
Commit Message
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
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;
> +};
...
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.
...
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
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
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.
@@ -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>
@@ -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:
@@ -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
@@ -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
new file mode 100644
@@ -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);
new file mode 100644
@@ -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 */
new file mode 100644
@@ -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 */