include/linux/bus/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 */
  16 struct 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  */
  30 struct 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  */
  55 int 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  */
  67 int 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  */
  76 void 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  */
  96 int 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  */
 113 void stm32_firewall_release_access_by_id(struct stm32_firewall *firewall, u32 subsystem_id);
 114
 115 #else /* CONFIG_STM32_FIREWALL */
 116
 117 int stm32_firewall_get_firewall(struct device_node *np, struct stm32_firewall *firewall,
 118                                 unsigned int nb_firewall);
 119 {
 120         return -ENODEV;
 121 }
 122
 123 int stm32_firewall_grant_access(struct stm32_firewall *firewall)
 124 {
 125         return -ENODEV;
 126 }
 127
 128 void stm32_firewall_release_access(struct stm32_firewall *firewall)
 129 {
 130 }
 131
 132 int stm32_firewall_grant_access_by_id(struct stm32_firewall *firewall, u32 subsystem_id)
 133 {
 134         return -ENODEV;
 135 }
 136
 137 void stm32_firewall_release_access_by_id(struct stm32_firewall *firewall, u32 subsystem_id)
 138 {
 139 }
 140
 141 #endif /* CONFIG_STM32_FIREWALL */
 142 #endif /* STM32_FIREWALL_DEVICE_H */