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 <asm/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_subsystem;
  55
  56 struct config_item {
  57         char                    *ci_name;
  58         char                    ci_namebuf[CONFIGFS_ITEM_NAME_LEN];
  59         struct kref             ci_kref;
  60         struct list_head        ci_entry;
  61         struct config_item      *ci_parent;
  62         struct config_group     *ci_group;
  63         struct config_item_type *ci_type;
  64         struct dentry           *ci_dentry;
  65 };
  66
  67 extern int config_item_set_name(struct config_item *, const char *, ...);
  68
  69 static inline char *config_item_name(struct config_item * item)
  70 {
  71         return item->ci_name;
  72 }
  73
  74 extern void config_item_init(struct config_item *);
  75 extern void config_item_init_type_name(struct config_item *item,
  76                                        const char *name,
  77                                        struct config_item_type *type);
  78
  79 extern struct config_item * config_item_get(struct config_item *);
  80 extern void config_item_put(struct config_item *);
  81
  82 struct config_item_type {
  83         struct module                           *ct_owner;
  84         struct configfs_item_operations         *ct_item_ops;
  85         struct configfs_group_operations        *ct_group_ops;
  86         struct configfs_attribute               **ct_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 config_group             **default_groups;
  98 };
  99
 100 extern void config_group_init(struct config_group *group);
 101 extern void config_group_init_type_name(struct config_group *group,
 102                                         const char *name,
 103                                         struct config_item_type *type);
 104
 105 static inline struct config_group *to_config_group(struct config_item *item)
 106 {
 107         return item ? container_of(item,struct config_group,cg_item) : NULL;
 108 }
 109
 110 static inline struct config_group *config_group_get(struct config_group *group)
 111 {
 112         return group ? to_config_group(config_item_get(&group->cg_item)) : NULL;
 113 }
 114
 115 static inline void config_group_put(struct config_group *group)
 116 {
 117         config_item_put(&group->cg_item);
 118 }
 119
 120 extern struct config_item *config_group_find_item(struct config_group *,
 121                                                   const char *);
 122
 123
 124 struct configfs_attribute {
 125         const char              *ca_name;
 126         struct module           *ca_owner;
 127         mode_t                  ca_mode;
 128 };
 129
 130 /*
 131  * Users often need to create attribute structures for their configurable
 132  * attributes, containing a configfs_attribute member and function pointers
 133  * for the show() and store() operations on that attribute. If they don't
 134  * need anything else on the extended attribute structure, they can use
 135  * this macro to define it  The argument _item is the name of the
 136  * config_item structure.
 137  */
 138 #define CONFIGFS_ATTR_STRUCT(_item)                                     \
 139 struct _item##_attribute {                                              \
 140         struct configfs_attribute attr;                                 \
 141         ssize_t (*show)(struct _item *, char *);                        \
 142         ssize_t (*store)(struct _item *, const char *, size_t);         \
 143 }
 144
 145 /*
 146  * With the extended attribute structure, users can use this macro
 147  * (similar to sysfs' __ATTR) to make defining attributes easier.
 148  * An example:
 149  * #define MYITEM_ATTR(_name, _mode, _show, _store)     \
 150  * struct myitem_attribute childless_attr_##_name =     \
 151  *         __CONFIGFS_ATTR(_name, _mode, _show, _store)
 152  */
 153 #define __CONFIGFS_ATTR(_name, _mode, _show, _store)                    \
 154 {                                                                       \
 155         .attr   = {                                                     \
 156                         .ca_name = __stringify(_name),                  \
 157                         .ca_mode = _mode,                               \
 158                         .ca_owner = THIS_MODULE,                        \
 159         },                                                              \
 160         .show   = _show,                                                \
 161         .store  = _store,                                               \
 162 }
 163 /* Here is a readonly version, only requiring a show() operation */
 164 #define __CONFIGFS_ATTR_RO(_name, _show)                                \
 165 {                                                                       \
 166         .attr   = {                                                     \
 167                         .ca_name = __stringify(_name),                  \
 168                         .ca_mode = 0444,                                \
 169                         .ca_owner = THIS_MODULE,                        \
 170         },                                                              \
 171         .show   = _show,                                                \
 172 }
 173
 174 /*
 175  * With these extended attributes, the simple show_attribute() and
 176  * store_attribute() operations need to call the show() and store() of the
 177  * attributes.  This is a common pattern, so we provide a macro to define
 178  * them.  The argument _item is the name of the config_item structure.
 179  * This macro expects the attributes to be named "struct <name>_attribute"
 180  * and the function to_<name>() to exist;
 181  */
 182 #define CONFIGFS_ATTR_OPS(_item)                                        \
 183 static ssize_t _item##_attr_show(struct config_item *item,              \
 184                                  struct configfs_attribute *attr,       \
 185                                  char *page)                            \
 186 {                                                                       \
 187         struct _item *_item = to_##_item(item);                         \
 188         struct _item##_attribute *_item##_attr =                        \
 189                 container_of(attr, struct _item##_attribute, attr);     \
 190         ssize_t ret = 0;                                                \
 191                                                                         \
 192         if (_item##_attr->show)                                         \
 193                 ret = _item##_attr->show(_item, page);                  \
 194         return ret;                                                     \
 195 }                                                                       \
 196 static ssize_t _item##_attr_store(struct config_item *item,             \
 197                                   struct configfs_attribute *attr,      \
 198                                   const char *page, size_t count)       \
 199 {                                                                       \
 200         struct _item *_item = to_##_item(item);                         \
 201         struct _item##_attribute *_item##_attr =                        \
 202                 container_of(attr, struct _item##_attribute, attr);     \
 203         ssize_t ret = -EINVAL;                                          \
 204                                                                         \
 205         if (_item##_attr->store)                                        \
 206                 ret = _item##_attr->store(_item, page, count);          \
 207         return ret;                                                     \
 208 }
 209
 210 /*
 211  * If allow_link() exists, the item can symlink(2) out to other
 212  * items.  If the item is a group, it may support mkdir(2).
 213  * Groups supply one of make_group() and make_item().  If the
 214  * group supports make_group(), one can create group children.  If it
 215  * supports make_item(), one can create config_item children.  make_group()
 216  * and make_item() return ERR_PTR() on errors.  If it has
 217  * default_groups on group->default_groups, it has automatically created
 218  * group children.  default_groups may coexist alongsize make_group() or
 219  * make_item(), but if the group wishes to have only default_groups
 220  * children (disallowing mkdir(2)), it need not provide either function.
 221  * If the group has commit(), it supports pending and commited (active)
 222  * items.
 223  */
 224 struct configfs_item_operations {
 225         void (*release)(struct config_item *);
 226         ssize_t (*show_attribute)(struct config_item *, struct configfs_attribute *,char *);
 227         ssize_t (*store_attribute)(struct config_item *,struct configfs_attribute *,const char *, size_t);
 228         int (*allow_link)(struct config_item *src, struct config_item *target);
 229         int (*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 /* These functions can sleep and can alloc with GFP_KERNEL */
 256 /* WARNING: These cannot be called underneath configfs callbacks!! */
 257 int configfs_depend_item(struct configfs_subsystem *subsys, struct config_item *target);
 258 void configfs_undepend_item(struct configfs_subsystem *subsys, struct config_item *target);
 259
 260 #endif /* _CONFIGFS_H_ */