[PATCH v6 05/11] firewall: introduce stm32_firewall framework

Gatien Chevallier
2023-10-10T13:00:58Z

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 V6:
- Renamed access-controller to access-controllers

Changes in V5:
- Rename feature-domain* to access-control*
- Fix index out of range in stm32_firewall_get_firewall()
- Add mising "select STM32_FIREWALL" in config ARCH_STM32 in
arch/arm/mach-stm32/Kconfig

Changes in V4:
- Fix documentation syntax
- Put node in case of error in stm32_firewall_populate_bus()
- Check firewall controller presence before using it in
stm32_firewall_controller_register()

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/arm/mach-stm32/Kconfig | 1 +
arch/arm64/Kconfig.platforms | 1 +
drivers/bus/Kconfig | 9 +
drivers/bus/Makefile | 1 +
drivers/bus/stm32_firewall.c | 294 ++++++++++++++++++++++
drivers/bus/stm32_firewall.h | 83 ++++++
include/linux/bus/stm32_firewall_device.h | 141 +++++++++++
8 files changed, 535 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

diff --git a/MAINTAINERS b/MAINTAINERS
index 6c4cce45a09d..70da7e1a2058 100644
--- a/MAINTAINERS
+++ b/MAINTAINERS
@@ -20293,6 +20293,11 @@ 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/arm/mach-stm32/Kconfig b/arch/arm/mach-stm32/Kconfig
index 98145031586f..ae21a9f78f9c 100644
--- a/arch/arm/mach-stm32/Kconfig
+++ b/arch/arm/mach-stm32/Kconfig
@@ -12,6 +12,7 @@ menuconfig ARCH_STM32
select PINCTRL
select RESET_CONTROLLER
select STM32_EXTI
+ select STM32_FIREWALL
help
Support for STMicroelectronics STM32 processors.

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 c98dd6ca2629..6c8d0725f193 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..68f41e7169ad
--- /dev/null
+++ b/drivers/bus/stm32_firewall.c
@@ -0,0 +1,294 @@
+// 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, "access-controllers", "#access-controller-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 access-controllers 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, "access-controller-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 second argument */
+ for (i = 0; i < provider_args.args_count - 1; 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;
+
+ if (!firewall_controller)
+ return -ENODEV;
+
+ pr_info("Registering %s firewall controller\n", firewall_controller->name);
+
+ 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 access-controllers property is mandatory for firewall bus devices */
+ len = of_count_phandle_with_args(child, "access-controllers",
+ "#access-controller-cells");
+ if (len <= 0) {
+ of_node_put(child);
+ return -EINVAL;
+ }
+
+ firewalls = kcalloc(len, sizeof(*firewalls), GFP_KERNEL);
+ if (!firewalls) {
+ of_node_put(child);
+ return -ENOMEM;
+ }
+
+ err = stm32_firewall_get_firewall(child, firewalls, (unsigned int)len);
+ if (err) {
+ kfree(firewalls);
+ of_node_put(child);
+ 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..e5fac85fe346
--- /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);
+};
+
+/**
+ * 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);
+
+/**
+ * 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..bbbee0b24ea8
--- /dev/null
+++ b/include/linux/bus/stm32_firewall_device.h
@@ -0,0 +1,141 @@
+/* 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;
+
+/**
+ * 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;
+};
+
+#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 access-controller property entries.
+ * The firewall ID is always the second argument of each of the
+ * access-controller 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 */
--
2.35.3