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/kernel.h>
  39 #include <linux/types.h>
  40 #include <linux/list.h>
  41 #include <linux/kref.h>
  42 #include <linux/mutex.h>
  43 #include <linux/err.h>
  44
  45 #include <linux/atomic.h>
  46
  47 #define CONFIGFS_ITEM_NAME_LEN  20
  48
  49 struct module;
  50
  51 struct configfs_item_operations;
  52 struct configfs_group_operations;
  53 struct configfs_attribute;
  54 struct configfs_bin_attribute;
  55 struct configfs_subsystem;
  56
  57 struct config_item {
  58         char                    *ci_name;
  59         char                    ci_namebuf[CONFIGFS_ITEM_NAME_LEN];
  60         struct kref             ci_kref;
  61         struct list_head        ci_entry;
  62         struct config_item      *ci_parent;
  63         struct config_group     *ci_group;
  64         struct config_item_type *ci_type;
  65         struct dentry           *ci_dentry;
  66 };
  67
  68 extern __printf(2, 3)
  69 int config_item_set_name(struct config_item *, const char *, ...);
  70
  71 static inline char *config_item_name(struct config_item * item)
  72 {
  73         return item->ci_name;
  74 }
  75
  76 extern void config_item_init_type_name(struct config_item *item,
  77                                        const char *name,
  78                                        struct config_item_type *type);
  79
  80 extern struct config_item * config_item_get(struct config_item *);
  81 extern void config_item_put(struct config_item *);
  82
  83 struct config_item_type {
  84         struct module                           *ct_owner;
  85         struct configfs_item_operations         *ct_item_ops;
  86         struct configfs_group_operations        *ct_group_ops;
  87         struct configfs_attribute               **ct_attrs;
  88         struct configfs_bin_attribute           **ct_bin_attrs;
  89 };
  90
  91 /**
  92  *      group - a group of config_items of a specific type, belonging
  93  *      to a specific subsystem.
  94  */
  95 struct config_group {
  96         struct config_item              cg_item;
  97         struct list_head                cg_children;
  98         struct configfs_subsystem       *cg_subsys;
  99         struct list_head                default_groups;
 100         struct list_head                group_entry;
 101 };
 102
 103 extern void config_group_init(struct config_group *group);
 104 extern void config_group_init_type_name(struct config_group *group,
 105                                         const char *name,
 106                                         struct config_item_type *type);
 107
 108 static inline struct config_group *to_config_group(struct config_item *item)
 109 {
 110         return item ? container_of(item,struct config_group,cg_item) : NULL;
 111 }
 112
 113 static inline struct config_group *config_group_get(struct config_group *group)
 114 {
 115         return group ? to_config_group(config_item_get(&group->cg_item)) : NULL;
 116 }
 117
 118 static inline void config_group_put(struct config_group *group)
 119 {
 120         config_item_put(&group->cg_item);
 121 }
 122
 123 extern struct config_item *config_group_find_item(struct config_group *,
 124                                                   const char *);
 125
 126
 127 static inline void configfs_add_default_group(struct config_group *new_group,
 128                 struct config_group *group)
 129 {
 130         list_add_tail(&new_group->group_entry, &group->default_groups);
 131 }
 132
 133 struct configfs_attribute {
 134         const char              *ca_name;
 135         struct module           *ca_owner;
 136         umode_t                 ca_mode;
 137         ssize_t (*show)(struct config_item *, char *);
 138         ssize_t (*store)(struct config_item *, const char *, size_t);
 139 };
 140
 141 #define CONFIGFS_ATTR(_pfx, _name)                      \
 142 static struct configfs_attribute _pfx##attr_##_name = { \
 143         .ca_name        = __stringify(_name),           \
 144         .ca_mode        = S_IRUGO | S_IWUSR,            \
 145         .ca_owner       = THIS_MODULE,                  \
 146         .show           = _pfx##_name##_show,           \
 147         .store          = _pfx##_name##_store,          \
 148 }
 149
 150 #define CONFIGFS_ATTR_RO(_pfx, _name)                   \
 151 static struct configfs_attribute _pfx##attr_##_name = { \
 152         .ca_name        = __stringify(_name),           \
 153         .ca_mode        = S_IRUGO,                      \
 154         .ca_owner       = THIS_MODULE,                  \
 155         .show           = _pfx##_name##_show,           \
 156 }
 157
 158 #define CONFIGFS_ATTR_WO(_pfx, _name)                   \
 159 static struct configfs_attribute _pfx##attr_##_name = { \
 160         .ca_name        = __stringify(_name),           \
 161         .ca_mode        = S_IWUSR,                      \
 162         .ca_owner       = THIS_MODULE,                  \
 163         .store          = _pfx##_name##_store,          \
 164 }
 165
 166 struct file;
 167 struct vm_area_struct;
 168
 169 struct configfs_bin_attribute {
 170         struct configfs_attribute cb_attr;      /* std. attribute */
 171         void *cb_private;                       /* for user       */
 172         size_t cb_max_size;                     /* max core size  */
 173         ssize_t (*read)(struct config_item *, void *, size_t);
 174         ssize_t (*write)(struct config_item *, const void *, size_t);
 175 };
 176
 177 #define CONFIGFS_BIN_ATTR(_pfx, _name, _priv, _maxsz)           \
 178 static struct configfs_bin_attribute _pfx##attr_##_name = {     \
 179         .cb_attr = {                                            \
 180                 .ca_name        = __stringify(_name),           \
 181                 .ca_mode        = S_IRUGO | S_IWUSR,            \
 182                 .ca_owner       = THIS_MODULE,                  \
 183         },                                                      \
 184         .cb_private     = _priv,                                \
 185         .cb_max_size    = _maxsz,                               \
 186         .read           = _pfx##_name##_read,                   \
 187         .write          = _pfx##_name##_write,                  \
 188 }
 189
 190 #define CONFIGFS_BIN_ATTR_RO(_pfx, _name, _priv, _maxsz)        \
 191 static struct configfs_bin_attribute _pfx##attr_##_name = {     \
 192         .cb_attr = {                                            \
 193                 .ca_name        = __stringify(_name),           \
 194                 .ca_mode        = S_IRUGO,                      \
 195                 .ca_owner       = THIS_MODULE,                  \
 196         },                                                      \
 197         .cb_private     = _priv,                                \
 198         .cb_max_size    = _maxsz,                               \
 199         .read           = _pfx##_name##_read,                   \
 200 }
 201
 202 #define CONFIGFS_BIN_ATTR_WO(_pfx, _name, _priv, _maxsz)        \
 203 static struct configfs_bin_attribute _pfx##attr_##_name = {     \
 204         .cb_attr = {                                            \
 205                 .ca_name        = __stringify(_name),           \
 206                 .ca_mode        = S_IWUSR,                      \
 207                 .ca_owner       = THIS_MODULE,                  \
 208         },                                                      \
 209         .cb_private     = _priv,                                \
 210         .cb_max_size    = _maxsz,                               \
 211         .write          = _pfx##_name##_write,                  \
 212 }
 213
 214 /*
 215  * If allow_link() exists, the item can symlink(2) out to other
 216  * items.  If the item is a group, it may support mkdir(2).
 217  * Groups supply one of make_group() and make_item().  If the
 218  * group supports make_group(), one can create group children.  If it
 219  * supports make_item(), one can create config_item children.  make_group()
 220  * and make_item() return ERR_PTR() on errors.  If it has
 221  * default_groups on group->default_groups, it has automatically created
 222  * group children.  default_groups may coexist alongsize make_group() or
 223  * make_item(), but if the group wishes to have only default_groups
 224  * children (disallowing mkdir(2)), it need not provide either function.
 225  * If the group has commit(), it supports pending and committed (active)
 226  * items.
 227  */
 228 struct configfs_item_operations {
 229         void (*release)(struct config_item *);
 230         int (*allow_link)(struct config_item *src, struct config_item *target);
 231         int (*drop_link)(struct config_item *src, struct config_item *target);
 232 };
 233
 234 struct configfs_group_operations {
 235         struct config_item *(*make_item)(struct config_group *group, const char *name);
 236         struct config_group *(*make_group)(struct config_group *group, const char *name);
 237         int (*commit_item)(struct config_item *item);
 238         void (*disconnect_notify)(struct config_group *group, struct config_item *item);
 239         void (*drop_item)(struct config_group *group, struct config_item *item);
 240 };
 241
 242 struct configfs_subsystem {
 243         struct config_group     su_group;
 244         struct mutex            su_mutex;
 245 };
 246
 247 static inline struct configfs_subsystem *to_configfs_subsystem(struct config_group *group)
 248 {
 249         return group ?
 250                 container_of(group, struct configfs_subsystem, su_group) :
 251                 NULL;
 252 }
 253
 254 int configfs_register_subsystem(struct configfs_subsystem *subsys);
 255 void configfs_unregister_subsystem(struct configfs_subsystem *subsys);
 256
 257 int configfs_register_group(struct config_group *parent_group,
 258                             struct config_group *group);
 259 void configfs_unregister_group(struct config_group *group);
 260
 261 void configfs_remove_default_groups(struct config_group *group);
 262
 263 struct config_group *
 264 configfs_register_default_group(struct config_group *parent_group,
 265                                 const char *name,
 266                                 struct config_item_type *item_type);
 267 void configfs_unregister_default_group(struct config_group *group);
 268
 269 /* These functions can sleep and can alloc with GFP_KERNEL */
 270 /* WARNING: These cannot be called underneath configfs callbacks!! */
 271 int configfs_depend_item(struct configfs_subsystem *subsys,
 272                          struct config_item *target);
 273 void configfs_undepend_item(struct config_item *target);
 274
 275 /*
 276  * These functions can sleep and can alloc with GFP_KERNEL
 277  * NOTE: These should be called only underneath configfs callbacks.
 278  * NOTE: First parameter is a caller's subsystem, not target's.
 279  * WARNING: These cannot be called on newly created item
 280  *        (in make_group()/make_item() callback)
 281  */
 282 int configfs_depend_item_unlocked(struct configfs_subsystem *caller_subsys,
 283                                   struct config_item *target);
 284
 285
 286 static inline void configfs_undepend_item_unlocked(struct config_item *target)
 287 {
 288         configfs_undepend_item(target);
 289 }
 290
 291 #endif /* _CONFIGFS_H_ */