diff options
Diffstat (limited to 'drivers/bus/stm32_firewall.c')
| -rw-r--r-- | drivers/bus/stm32_firewall.c | 294 |
1 files changed, 294 insertions, 0 deletions
diff --git a/drivers/bus/stm32_firewall.c b/drivers/bus/stm32_firewall.c new file mode 100644 index 000000000000..2fc9761dadec --- /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_detach_node(child); + 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); |