include/linux/configfs.h

   1 /* -*- mode: c; c-basic-offset: 8; -*-
   2  * vim: noexpandtab sw=8 ts=8 sts=0:
   3  *
   4  * configfs.h - definitions for the device driver filesystem
   5  *
   6  * This program is free software; you can redistribute it and/or
   7  * modify it under the terms of the GNU General Public
   8  * License as published by the Free Software Foundation; either
   9  * version 2 of the License, or (at your option) any later version.
  10  *
  11  * This program is distributed in the hope that it will be useful,
  12  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  13  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  14  * General Public License for more details.
  15  *
  16  * You should have received a copy of the GNU General Public
  17  * License along with this program; if not, write to the
  18  * Free Software Foundation, Inc., 59 Temple Place - Suite 330,
  19  * Boston, MA 021110-1307, USA.
  20  *
  21  * Based on sysfs:
  22  *      sysfs is Copyright (C) 2001, 2002, 2003 Patrick Mochel
  23  *
  24  * Based on kobject.h:
  25  *      Copyright (c) 2002-2003 Patrick Mochel
  26  *      Copyright (c) 2002-2003 Open Source Development Labs
  27  *
  28  * configfs Copyright (C) 2005 Oracle.  All rights reserved.
  29  *
  30  * Please read Documentation/filesystems/configfs/configfs.txt before using
  31  * the configfs interface, ESPECIALLY the parts about reference counts and
  32  * item destructors.
  33  */
  34
  35 #ifndef _CONFIGFS_H_
  36 #define _CONFIGFS_H_
  37
  38 #include <linux/stat.h>   /* S_IRUGO */
  39 #include <linux/types.h>  /* ssize_t */
  40 #include <linux/list.h>   /* struct list_head */
  41 #include <linux/kref.h>   /* struct kref */
  42 #include <linux/mutex.h>  /* struct mutex */
  43
  44 #define CONFIGFS_ITEM_NAME_LEN  20
  45
  46 struct module;
  47
  48 struct configfs_item_operations;
  49 struct configfs_group_operations;
  50 struct configfs_attribute;
  51 struct configfs_bin_attribute;
  52 struct configfs_subsystem;
  53
  54 struct config_item {
  55         char                    *ci_name;
  56         char                    ci_namebuf[CONFIGFS_ITEM_NAME_LEN];
  57         struct kref             ci_kref;
  58         struct list_head        ci_entry;
  59         struct config_item      *ci_parent;
  60         struct config_group     *ci_group;
  61         const struct config_item_type   *ci_type;
  62         struct dentry           *ci_dentry;
  63 };
  64
  65 extern __printf(2, 3)
  66 int config_item_set_name(struct config_item *, const char *, ...);
  67
  68 static inline char *config_item_name(struct config_item * item)
  69 {
  70         return item->ci_name;
  71 }
  72
  73 extern void config_item_init_type_name(struct config_item *item,
  74                                        const char *name,
  75                                        const struct config_item_type *type);
  76
  77 extern struct config_item *config_item_get(struct config_item *);
  78 extern struct config_item *config_item_get_unless_zero(struct config_item *);
  79 extern void config_item_put(struct config_item *);
  80
  81 struct config_item_type {
  82         struct module                           *ct_owner;
  83         struct configfs_item_operations         *ct_item_ops;
  84         struct configfs_group_operations        *ct_group_ops;
  85         struct configfs_attribute               **ct_attrs;
  86         struct configfs_bin_attribute           **ct_bin_attrs;
  87 };
  88
  89 /**
  90  *      group - a group of config_items of a specific type, belonging
  91  *      to a specific subsystem.
  92  */
  93 struct config_group {
  94         struct config_item              cg_item;
  95         struct list_head                cg_children;
  96         struct configfs_subsystem       *cg_subsys;
  97         struct list_head                default_groups;
  98         struct list_head                group_entry;
  99 };
 100
 101 extern void config_group_init(struct config_group *group);
 102 extern void config_group_init_type_name(struct config_group *group,
 103                                         const char *name,
 104                                         const struct config_item_type *type);
 105
 106 static inline struct config_group *to_config_group(struct config_item *item)
 107 {
 108         return item ? container_of(item,struct config_group,cg_item) : NULL;
 109 }
 110
 111 static inline struct config_group *config_group_get(struct config_group *group)
 112 {
 113         return group ? to_config_group(config_item_get(&group->cg_item)) : NULL;
 114 }
 115
 116 static inline void config_group_put(struct config_group *group)
 117 {
 118         config_item_put(&group->cg_item);
 119 }
 120
 121 extern struct config_item *config_group_find_item(struct config_group *,
 122                                                   const char *);
 123
 124
 125 static inline void configfs_add_default_group(struct config_group *new_group,
 126                 struct config_group *group)
 127 {
 128         list_add_tail(&new_group->group_entry, &group->default_groups);
 129 }
 130
 131 struct configfs_attribute {
 132         const char              *ca_name;
 133         struct module           *ca_owner;
 134         umode_t                 ca_mode;
 135         ssize_t (*show)(struct config_item *, char *);
 136         ssize_t (*store)(struct config_item *, const char *, size_t);
 137 };
 138
 139 #define CONFIGFS_ATTR(_pfx, _name)                      \
 140 static struct configfs_attribute _pfx##attr_##_name = { \
 141         .ca_name        = __stringify(_name),           \
 142         .ca_mode        = S_IRUGO | S_IWUSR,            \
 143         .ca_owner       = THIS_MODULE,                  \
 144         .show           = _pfx##_name##_show,           \
 145         .store          = _pfx##_name##_store,          \
 146 }
 147
 148 #define CONFIGFS_ATTR_RO(_pfx, _name)                   \
 149 static struct configfs_attribute _pfx##attr_##_name = { \
 150         .ca_name        = __stringify(_name),           \
 151         .ca_mode        = S_IRUGO,                      \
 152         .ca_owner       = THIS_MODULE,                  \
 153         .show           = _pfx##_name##_show,           \
 154 }
 155
 156 #define CONFIGFS_ATTR_WO(_pfx, _name)                   \
 157 static struct configfs_attribute _pfx##attr_##_name = { \
 158         .ca_name        = __stringify(_name),           \
 159         .ca_mode        = S_IWUSR,                      \
 160         .ca_owner       = THIS_MODULE,                  \
 161         .store          = _pfx##_name##_store,          \
 162 }
 163
 164 struct file;
 165 struct vm_area_struct;
 166
 167 struct configfs_bin_attribute {
 168         struct configfs_attribute cb_attr;      /* std. attribute */
 169         void *cb_private;                       /* for user       */
 170         size_t cb_max_size;                     /* max core size  */
 171         ssize_t (*read)(struct config_item *, void *, size_t);
 172         ssize_t (*write)(struct config_item *, const void *, size_t);
 173 };
 174
 175 #define CONFIGFS_BIN_ATTR(_pfx, _name, _priv, _maxsz)           \
 176 static struct configfs_bin_attribute _pfx##attr_##_name = {     \
 177         .cb_attr = {                                            \
 178                 .ca_name        = __stringify(_name),           \
 179                 .ca_mode        = S_IRUGO | S_IWUSR,            \
 180                 .ca_owner       = THIS_MODULE,                  \
 181         },                                                      \
 182         .cb_private     = _priv,                                \
 183         .cb_max_size    = _maxsz,                               \
 184         .read           = _pfx##_name##_read,                   \
 185         .write          = _pfx##_name##_write,                  \
 186 }
 187
 188 #define CONFIGFS_BIN_ATTR_RO(_pfx, _name, _priv, _maxsz)        \
 189 static struct configfs_bin_attribute _pfx##attr_##_name = {     \
 190         .cb_attr = {                                            \
 191                 .ca_name        = __stringify(_name),           \
 192                 .ca_mode        = S_IRUGO,                      \
 193                 .ca_owner       = THIS_MODULE,                  \
 194         },                                                      \
 195         .cb_private     = _priv,                                \
 196         .cb_max_size    = _maxsz,                               \
 197         .read           = _pfx##_name##_read,                   \
 198 }
 199
 200 #define CONFIGFS_BIN_ATTR_WO(_pfx, _name, _priv, _maxsz)        \
 201 static struct configfs_bin_attribute _pfx##attr_##_name = {     \
 202         .cb_attr = {                                            \
 203                 .ca_name        = __stringify(_name),           \
 204                 .ca_mode        = S_IWUSR,                      \
 205                 .ca_owner       = THIS_MODULE,                  \
 206         },                                                      \
 207         .cb_private     = _priv,                                \
 208         .cb_max_size    = _maxsz,                               \
 209         .write          = _pfx##_name##_write,                  \
 210 }
 211
 212 /*
 213  * If allow_link() exists, the item can symlink(2) out to other
 214  * items.  If the item is a group, it may support mkdir(2).
 215  * Groups supply one of make_group() and make_item().  If the
 216  * group supports make_group(), one can create group children.  If it
 217  * supports make_item(), one can create config_item children.  make_group()
 218  * and make_item() return ERR_PTR() on errors.  If it has
 219  * default_groups on group->default_groups, it has automatically created
 220  * group children.  default_groups may coexist alongsize make_group() or
 221  * make_item(), but if the group wishes to have only default_groups
 222  * children (disallowing mkdir(2)), it need not provide either function.
 223  * If the group has commit(), it supports pending and committed (active)
 224  * items.
 225  */
 226 struct configfs_item_operations {
 227         void (*release)(struct config_item *);
 228         int (*allow_link)(struct config_item *src, struct config_item *target);
 229         void (*drop_link)(struct config_item *src, struct config_item *target);
 230 };
 231
 232 struct configfs_group_operations {
 233         struct config_item *(*make_item)(struct config_group *group, const char *name);
 234         struct config_group *(*make_group)(struct config_group *group, const char *name);
 235         int (*commit_item)(struct config_item *item);
 236         void (*disconnect_notify)(struct config_group *group, struct config_item *item);
 237         void (*drop_item)(struct config_group *group, struct config_item *item);
 238 };
 239
 240 struct configfs_subsystem {
 241         struct config_group     su_group;
 242         struct mutex            su_mutex;
 243 };
 244
 245 static inline struct configfs_subsystem *to_configfs_subsystem(struct config_group *group)
 246 {
 247         return group ?
 248                 container_of(group, struct configfs_subsystem, su_group) :
 249                 NULL;
 250 }
 251
 252 int configfs_register_subsystem(struct configfs_subsystem *subsys);
 253 void configfs_unregister_subsystem(struct configfs_subsystem *subsys);
 254
 255 int configfs_register_group(struct config_group *parent_group,
 256                             struct config_group *group);
 257 void configfs_unregister_group(struct config_group *group);
 258
 259 void configfs_remove_default_groups(struct config_group *group);
 260
 261 struct config_group *
 262 configfs_register_default_group(struct config_group *parent_group,
 263                                 const char *name,
 264                                 const struct config_item_type *item_type);
 265 void configfs_unregister_default_group(struct config_group *group);
 266
 267 /* These functions can sleep and can alloc with GFP_KERNEL */
 268 /* WARNING: These cannot be called underneath configfs callbacks!! */
 269 int configfs_depend_item(struct configfs_subsystem *subsys,
 270                          struct config_item *target);
 271 void configfs_undepend_item(struct config_item *target);
 272
 273 /*
 274  * These functions can sleep and can alloc with GFP_KERNEL
 275  * NOTE: These should be called only underneath configfs callbacks.
 276  * NOTE: First parameter is a caller's subsystem, not target's.
 277  * WARNING: These cannot be called on newly created item
 278  *        (in make_group()/make_item() callback)
 279  */
 280 int configfs_depend_item_unlocked(struct configfs_subsystem *caller_subsys,
 281                                   struct config_item *target);
 282
 283
 284 static inline void configfs_undepend_item_unlocked(struct config_item *target)
 285 {
 286         configfs_undepend_item(target);
 287 }
 288
 289 #endif /* _CONFIGFS_H_ */