+ if (err) {
+ pr_err("Unable to get feature-domains property for node %s\n", np->full_name);
+ return err;
+ }
+
+ /* Parse property with phandle parsed out */
+ err = of_parse_phandle_with_args(np, "feature-domains", "#feature-domain-cells", 0, &args);
+ if (err) {
+ pr_err("Unable to read feature-domains arguments for node %s\n", np->full_name);
+ return err;
+ }
+
+ /* The phandle is parsed out */
+ if (args.args_count > STM32_FIREWALL_MAX_ARGS - 1)
+ return -EINVAL;
+
+ of_node_put(np);
+
+ /* 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 == controller_phandle) {
+ match = true;
+ firewall->firewall_ctrl = ctrl;
+ break;
+ }
+ }
+ mutex_unlock(&firewall_controller_list_lock);
+ if (!match) {
+ firewall->firewall_ctrl = NULL;
+ pr_err("No firewall controller registered for %s\n", np->full_name);
+ return -ENODEV;
+ }
+
+ /*
+ * The firewall ID is always the second argument of the feature-domains property.
+ * The first argument is already parsed out, so args.args[0] is the second argument.
+ */
+ firewall->firewall_id = args.args[0];
+
+ /* Extra args start at the third argument */
+ for (i = 0; i < args.args_count; i++)
+ firewall->extra_args[i] = args.args[i + 1];
+
+ /* Remove the firewall ID arg that is not an extra argument */
+ if (args.args_count >= 1)
+ firewall->extra_args_size = args.args_count - 1;
+
+ 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_err("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, 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_err("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)
+{
+ pr_info("Registering firewall controller %s", dev_name(firewall_controller->dev));
+
+ if (!firewall_controller)
+ return -ENODEV;
+
+ mutex_lock(&firewall_controller_list_lock);
+ list_add_tail(&firewall_controller->entry, &firewall_controller_list);
+ mutex_unlock(&firewall_controller_list_lock);
+
+ return 0;
+
+}
+
+void stm32_firewall_controller_unregister(struct stm32_firewall_controller *firewall_controller)
+{
+ struct stm32_firewall_controller *ctrl, *tmp;
+ bool controller_removed = false;
+
+ if (!firewall_controller) {
+ pr_debug("Null reference while unregistering firewall controller");
+ return;
+ }
+
+ mutex_lock(&firewall_controller_list_lock);
+ list_for_each_entry_safe(ctrl, tmp, &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",
+ dev_name(firewall_controller->dev));
+}
+
+void stm32_firewall_populate_bus(struct stm32_firewall_controller *firewall_controller)
+{
+ struct device_node *child;
+ struct device *parent;
+ u32 firewall_id;
+ 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) {
+ err = stm32_firewall_get_id(child, &firewall_id);
+ if (err < 0 ||
+ firewall_controller->grant_access(firewall_controller, 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);
+ }
+ }
+}
diff --git a/drivers/bus/stm32_firewall.h b/drivers/bus/stm32_firewall.h
new file mode 100644
index 000000000000..8d92e8c1ab77
--- /dev/null
+++ b/drivers/bus/stm32_firewall.h
@@ -0,0 +1,83 @@
+/* SPDX-License-Identifier: GPL-2.0-or-later */
+/*
+ * 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_RESOURCE_FIREWALL: This type of firewall protects internal resources
+ * STM32_NOTYPE_FIREWALL: Undefined firewall type
+ */
+
+#define STM32_PERIPHERAL_FIREWALL BIT(1)
+#define STM32_MEMORY_FIREWALL BIT(2)
+#define STM32_RESOURCE_FIREWALL BIT(3)
+#define STM32_NOTYPE_FIREWALL BIT(4)
+
+/**
+ * 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
+ */
+void 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..ccaecea7fc6c
--- /dev/null
+++ b/include/linux/bus/stm32_firewall_device.h
@@ -0,0 +1,134 @@
+/* SPDX-License-Identifier: GPL-2.0-or-later */
+/*
+ * 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
+ * @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];
+ 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 the feature-domains property.
+ * The firewall ID is always the second argument of the
+ * feature-domains property.
+ *
+ * @np Device node to parse
+ * @firewall Resulting firewall reference(s)
+ *
+ * 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);
+
+/**
+ * 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 */
--
2.25.1
