stm32_firewall_device.h

  1/* SPDX-License-Identifier: GPL-2.0-only */
  2/*
  3 * Copyright (C) 2023, STMicroelectronics - All Rights Reserved
  4 */
  5
  6#ifndef STM32_FIREWALL_DEVICE_H
  7#define STM32_FIREWALL_DEVICE_H
  8
  9#include <linux/of.h>
 10#include <linux/platform_device.h>
 11#include <linux/types.h>
 12
 13#define STM32_FIREWALL_MAX_EXTRA_ARGS		5
 14
 15/* Opaque reference to stm32_firewall_controller */
 16struct stm32_firewall_controller;
 17
 18/**
 19 * struct stm32_firewall - Information on a device's firewall. Each device can have more than one
 20 *			   firewall.
 21 *
 22 * @firewall_ctrl:		Pointer referencing a firewall controller of the device. It is
 23 *				opaque so a device cannot manipulate the controller's ops or access
 24 *				the controller's data
 25 * @extra_args:			Extra arguments that are implementation dependent
 26 * @entry:			Name of the firewall entry
 27 * @extra_args_size:		Number of extra arguments
 28 * @firewall_id:		Firewall ID associated the device for this firewall controller
 29 */
 30struct stm32_firewall {
 31	struct stm32_firewall_controller *firewall_ctrl;
 32	u32 extra_args[STM32_FIREWALL_MAX_EXTRA_ARGS];
 33	const char *entry;
 34	size_t extra_args_size;
 35	u32 firewall_id;
 36};
 37
 38#if IS_ENABLED(CONFIG_STM32_FIREWALL)
 39/**
 40 * stm32_firewall_get_firewall - Get the firewall(s) associated to given device.
 41 *				 The firewall controller reference is always the first argument
 42 *				 of each of the access-controller property entries.
 43 *				 The firewall ID is always the second argument of each of the
 44 *				 access-controller  property entries.
 45 *				 If there's no argument linked to the phandle, then the firewall ID
 46 *				 field is set to U32_MAX, which is an invalid ID.
 47 *
 48 * @np:				Device node to parse
 49 * @firewall:			Array of firewall references
 50 * @nb_firewall:		Number of firewall references to get. Must be at least 1.
 51 *
 52 * Returns 0 on success, -ENODEV if there's no match with a firewall controller or appropriate errno
 53 * code if error occurred.
 54 */
 55int stm32_firewall_get_firewall(struct device_node *np, struct stm32_firewall *firewall,
 56				unsigned int nb_firewall);
 57
 58/**
 59 * stm32_firewall_grant_access - Request firewall access rights and grant access.
 60 *
 61 * @firewall:			Firewall reference containing the ID to check against its firewall
 62 *				controller
 63 *
 64 * Returns 0 if access is granted, -EACCES if access is denied, -ENODEV if firewall is null or
 65 * appropriate errno code if error occurred
 66 */
 67int stm32_firewall_grant_access(struct stm32_firewall *firewall);
 68
 69/**
 70 * stm32_firewall_release_access - Release access granted from a call to
 71 *				   stm32_firewall_grant_access().
 72 *
 73 * @firewall:			Firewall reference containing the ID to check against its firewall
 74 *				controller
 75 */
 76void stm32_firewall_release_access(struct stm32_firewall *firewall);
 77
 78/**
 79 * stm32_firewall_grant_access_by_id - Request firewall access rights of a given device
 80 *				       based on a specific firewall ID
 81 *
 82 * Warnings:
 83 * There is no way to ensure that the given ID will correspond to the firewall referenced in the
 84 * device node if the ID did not come from stm32_firewall_get_firewall(). In that case, this
 85 * function must be used with caution.
 86 * This function should be used for subsystem resources that do not have the same firewall ID
 87 * as their parent.
 88 * U32_MAX is an invalid ID.
 89 *
 90 * @firewall:			Firewall reference containing the firewall controller
 91 * @subsystem_id:		Firewall ID of the subsystem resource
 92 *
 93 * Returns 0 if access is granted, -EACCES if access is denied, -ENODEV if firewall is null or
 94 * appropriate errno code if error occurred
 95 */
 96int stm32_firewall_grant_access_by_id(struct stm32_firewall *firewall, u32 subsystem_id);
 97
 98/**
 99 * stm32_firewall_release_access_by_id - Release access granted from a call to
100 *					 stm32_firewall_grant_access_by_id().
101 *
102 * Warnings:
103 * There is no way to ensure that the given ID will correspond to the firewall referenced in the
104 * device node if the ID did not come from stm32_firewall_get_firewall(). In that case, this
105 * function must be used with caution.
106 * This function should be used for subsystem resources that do not have the same firewall ID
107 * as their parent.
108 * U32_MAX is an invalid ID.
109 *
110 * @firewall:			Firewall reference containing the firewall controller
111 * @subsystem_id:		Firewall ID of the subsystem resource
112 */
113void stm32_firewall_release_access_by_id(struct stm32_firewall *firewall, u32 subsystem_id);
114
115#else /* CONFIG_STM32_FIREWALL */
116
117static inline int stm32_firewall_get_firewall(struct device_node *np,
118					      struct stm32_firewall *firewall,
119					      unsigned int nb_firewall)
120{
121	return -ENODEV;
122}
123
124static inline int stm32_firewall_grant_access(struct stm32_firewall *firewall)
125{
126	return -ENODEV;
127}
128
129static inline void stm32_firewall_release_access(struct stm32_firewall *firewall)
130{
131}
132
133static inline int stm32_firewall_grant_access_by_id(struct stm32_firewall *firewall,
134						    u32 subsystem_id)
135{
136	return -ENODEV;
137}
138
139static inline void stm32_firewall_release_access_by_id(struct stm32_firewall *firewall,
140						       u32 subsystem_id)
141{
142}
143
144#endif /* CONFIG_STM32_FIREWALL */
145#endif /* STM32_FIREWALL_DEVICE_H */