include/linux/configfs.h

   1 /* SPDX-License-Identifier: GPL-2.0-or-later */
   2 /* -*- mode: c; c-basic-offset: 8; -*-
   3  * vim: noexpandtab sw=8 ts=8 sts=0:
   4  *
   5  * configfs.h - definitions for the device driver filesystem
   6  *
   7  * Based on sysfs:
   8  *      sysfs is Copyright (C) 2001, 2002, 2003 Patrick Mochel
   9  *
  10  * Based on kobject.h:
  11  *      Copyright (c) 2002-2003 Patrick Mochel
  12  *      Copyright (c) 2002-2003 Open Source Development Labs
  13  *
  14  * configfs Copyright (C) 2005 Oracle.  All rights reserved.
  15  *
  16  * Please read Documentation/filesystems/configfs/configfs.txt before using
  17  * the configfs interface, ESPECIALLY the parts about reference counts and
  18  * item destructors.
  19  */
  20
  21 #ifndef _CONFIGFS_H_
  22 #define _CONFIGFS_H_
  23
  24 #include <linux/stat.h>   /* S_IRUGO */
  25 #include <linux/types.h>  /* ssize_t */
  26 #include <linux/list.h>   /* struct list_head */
  27 #include <linux/kref.h>   /* struct kref */
  28 #include <linux/mutex.h>  /* struct mutex */
  29
  30 #define CONFIGFS_ITEM_NAME_LEN  20
  31
  32 struct module;
  33
  34 struct configfs_item_operations;
  35 struct configfs_group_operations;
  36 struct configfs_attribute;
  37 struct configfs_bin_attribute;
  38 struct configfs_subsystem;
  39
  40 struct config_item {
  41         char                    *ci_name;
  42         char                    ci_namebuf[CONFIGFS_ITEM_NAME_LEN];
  43         struct kref             ci_kref;
  44         struct list_head        ci_entry;
  45         struct config_item      *ci_parent;
  46         struct config_group     *ci_group;
  47         const struct config_item_type   *ci_type;
  48         struct dentry           *ci_dentry;
  49 };
  50
  51 extern __printf(2, 3)
  52 int config_item_set_name(struct config_item *, const char *, ...);
  53
  54 static inline char *config_item_name(struct config_item * item)
  55 {
  56         return item->ci_name;
  57 }
  58
  59 extern void config_item_init_type_name(struct config_item *item,
  60                                        const char *name,
  61                                        const struct config_item_type *type);
  62
  63 extern struct config_item *config_item_get(struct config_item *);
  64 extern struct config_item *config_item_get_unless_zero(struct config_item *);
  65 extern void config_item_put(struct config_item *);
  66
  67 struct config_item_type {
  68         struct module                           *ct_owner;
  69         struct configfs_item_operations         *ct_item_ops;
  70         struct configfs_group_operations        *ct_group_ops;
  71         struct configfs_attribute               **ct_attrs;
  72         struct configfs_bin_attribute           **ct_bin_attrs;
  73 };
  74
  75 /**
  76  *      group - a group of config_items of a specific type, belonging
  77  *      to a specific subsystem.
  78  */
  79 struct config_group {
  80         struct config_item              cg_item;
  81         struct list_head                cg_children;
  82         struct configfs_subsystem       *cg_subsys;
  83         struct list_head                default_groups;
  84         struct list_head                group_entry;
  85 };
  86
  87 extern void config_group_init(struct config_group *group);
  88 extern void config_group_init_type_name(struct config_group *group,
  89                                         const char *name,
  90                                         const struct config_item_type *type);
  91
  92 static inline struct config_group *to_config_group(struct config_item *item)
  93 {
  94         return item ? container_of(item,struct config_group,cg_item) : NULL;
  95 }
  96
  97 static inline struct config_group *config_group_get(struct config_group *group)
  98 {
  99         return group ? to_config_group(config_item_get(&group->cg_item)) : NULL;
 100 }
 101
 102 static inline void config_group_put(struct config_group *group)
 103 {
 104         config_item_put(&group->cg_item);
 105 }
 106
 107 extern struct config_item *config_group_find_item(struct config_group *,
 108                                                   const char *);
 109
 110
 111 static inline void configfs_add_default_group(struct config_group *new_group,
 112                 struct config_group *group)
 113 {
 114         list_add_tail(&new_group->group_entry, &group->default_groups);
 115 }
 116
 117 struct configfs_attribute {
 118         const char              *ca_name;
 119         struct module           *ca_owner;
 120         umode_t                 ca_mode;
 121         ssize_t (*show)(struct config_item *, char *);
 122         ssize_t (*store)(struct config_item *, const char *, size_t);
 123 };
 124
 125 #define CONFIGFS_ATTR(_pfx, _name)                      \
 126 static struct configfs_attribute _pfx##attr_##_name = { \
 127         .ca_name        = __stringify(_name),           \
 128         .ca_mode        = S_IRUGO | S_IWUSR,            \
 129         .ca_owner       = THIS_MODULE,                  \
 130         .show           = _pfx##_name##_show,           \
 131         .store          = _pfx##_name##_store,          \
 132 }
 133
 134 #define CONFIGFS_ATTR_RO(_pfx, _name)                   \
 135 static struct configfs_attribute _pfx##attr_##_name = { \
 136         .ca_name        = __stringify(_name),           \
 137         .ca_mode        = S_IRUGO,                      \
 138         .ca_owner       = THIS_MODULE,                  \
 139         .show           = _pfx##_name##_show,           \
 140 }
 141
 142 #define CONFIGFS_ATTR_WO(_pfx, _name)                   \
 143 static struct configfs_attribute _pfx##attr_##_name = { \
 144         .ca_name        = __stringify(_name),           \
 145         .ca_mode        = S_IWUSR,                      \
 146         .ca_owner       = THIS_MODULE,                  \
 147         .store          = _pfx##_name##_store,          \
 148 }
 149
 150 struct file;
 151 struct vm_area_struct;
 152
 153 struct configfs_bin_attribute {
 154         struct configfs_attribute cb_attr;      /* std. attribute */
 155         void *cb_private;                       /* for user       */
 156         size_t cb_max_size;                     /* max core size  */
 157         ssize_t (*read)(struct config_item *, void *, size_t);
 158         ssize_t (*write)(struct config_item *, const void *, size_t);
 159 };
 160
 161 #define CONFIGFS_BIN_ATTR(_pfx, _name, _priv, _maxsz)           \
 162 static struct configfs_bin_attribute _pfx##attr_##_name = {     \
 163         .cb_attr = {                                            \
 164                 .ca_name        = __stringify(_name),           \
 165                 .ca_mode        = S_IRUGO | S_IWUSR,            \
 166                 .ca_owner       = THIS_MODULE,                  \
 167         },                                                      \
 168         .cb_private     = _priv,                                \
 169         .cb_max_size    = _maxsz,                               \
 170         .read           = _pfx##_name##_read,                   \
 171         .write          = _pfx##_name##_write,                  \
 172 }
 173
 174 #define CONFIGFS_BIN_ATTR_RO(_pfx, _name, _priv, _maxsz)        \
 175 static struct configfs_bin_attribute _pfx##attr_##_name = {     \
 176         .cb_attr = {                                            \
 177                 .ca_name        = __stringify(_name),           \
 178                 .ca_mode        = S_IRUGO,                      \
 179                 .ca_owner       = THIS_MODULE,                  \
 180         },                                                      \
 181         .cb_private     = _priv,                                \
 182         .cb_max_size    = _maxsz,                               \
 183         .read           = _pfx##_name##_read,                   \
 184 }
 185
 186 #define CONFIGFS_BIN_ATTR_WO(_pfx, _name, _priv, _maxsz)        \
 187 static struct configfs_bin_attribute _pfx##attr_##_name = {     \
 188         .cb_attr = {                                            \
 189                 .ca_name        = __stringify(_name),           \
 190                 .ca_mode        = S_IWUSR,                      \
 191                 .ca_owner       = THIS_MODULE,                  \
 192         },                                                      \
 193         .cb_private     = _priv,                                \
 194         .cb_max_size    = _maxsz,                               \
 195         .write          = _pfx##_name##_write,                  \
 196 }
 197
 198 /*
 199  * If allow_link() exists, the item can symlink(2) out to other
 200  * items.  If the item is a group, it may support mkdir(2).
 201  * Groups supply one of make_group() and make_item().  If the
 202  * group supports make_group(), one can create group children.  If it
 203  * supports make_item(), one can create config_item children.  make_group()
 204  * and make_item() return ERR_PTR() on errors.  If it has
 205  * default_groups on group->default_groups, it has automatically created
 206  * group children.  default_groups may coexist alongsize make_group() or
 207  * make_item(), but if the group wishes to have only default_groups
 208  * children (disallowing mkdir(2)), it need not provide either function.
 209  * If the group has commit(), it supports pending and committed (active)
 210  * items.
 211  */
 212 struct configfs_item_operations {
 213         void (*release)(struct config_item *);
 214         int (*allow_link)(struct config_item *src, struct config_item *target);
 215         void (*drop_link)(struct config_item *src, struct config_item *target);
 216 };
 217
 218 struct configfs_group_operations {
 219         struct config_item *(*make_item)(struct config_group *group, const char *name);
 220         struct config_group *(*make_group)(struct config_group *group, const char *name);
 221         int (*commit_item)(struct config_item *item);
 222         void (*disconnect_notify)(struct config_group *group, struct config_item *item);
 223         void (*drop_item)(struct config_group *group, struct config_item *item);
 224 };
 225
 226 struct configfs_subsystem {
 227         struct config_group     su_group;
 228         struct mutex            su_mutex;
 229 };
 230
 231 static inline struct configfs_subsystem *to_configfs_subsystem(struct config_group *group)
 232 {
 233         return group ?
 234                 container_of(group, struct configfs_subsystem, su_group) :
 235                 NULL;
 236 }
 237
 238 int configfs_register_subsystem(struct configfs_subsystem *subsys);
 239 void configfs_unregister_subsystem(struct configfs_subsystem *subsys);
 240
 241 int configfs_register_group(struct config_group *parent_group,
 242                             struct config_group *group);
 243 void configfs_unregister_group(struct config_group *group);
 244
 245 void configfs_remove_default_groups(struct config_group *group);
 246
 247 struct config_group *
 248 configfs_register_default_group(struct config_group *parent_group,
 249                                 const char *name,
 250                                 const struct config_item_type *item_type);
 251 void configfs_unregister_default_group(struct config_group *group);
 252
 253 /* These functions can sleep and can alloc with GFP_KERNEL */
 254 /* WARNING: These cannot be called underneath configfs callbacks!! */
 255 int configfs_depend_item(struct configfs_subsystem *subsys,
 256                          struct config_item *target);
 257 void configfs_undepend_item(struct config_item *target);
 258
 259 /*
 260  * These functions can sleep and can alloc with GFP_KERNEL
 261  * NOTE: These should be called only underneath configfs callbacks.
 262  * NOTE: First parameter is a caller's subsystem, not target's.
 263  * WARNING: These cannot be called on newly created item
 264  *        (in make_group()/make_item() callback)
 265  */
 266 int configfs_depend_item_unlocked(struct configfs_subsystem *caller_subsys,
 267                                   struct config_item *target);
 268
 269
 270 static inline void configfs_undepend_item_unlocked(struct config_item *target)
 271 {
 272         configfs_undepend_item(target);
 273 }
 274
 275 #endif /* _CONFIGFS_H_ */