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.txt before using the
  31  * configfs interface, ESPECIALLY the parts about reference counts and
  32  * item destructors.
  33  */
  34
  35 #ifndef _CONFIGFS_H_
  36 #define _CONFIGFS_H_
  37
  38 #ifdef __KERNEL__
  39
  40 #include <linux/kernel.h>
  41 #include <linux/types.h>
  42 #include <linux/list.h>
  43 #include <linux/kref.h>
  44 #include <linux/mutex.h>
  45
  46 #include <asm/atomic.h>
  47
  48 #define CONFIGFS_ITEM_NAME_LEN  20
  49
  50 struct module;
  51
  52 struct configfs_item_operations;
  53 struct configfs_group_operations;
  54 struct configfs_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 int config_item_set_name(struct config_item *, const char *, ...);
  69
  70 static inline char *config_item_name(struct config_item * item)
  71 {
  72         return item->ci_name;
  73 }
  74
  75 extern void config_item_init(struct config_item *);
  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 };
  89
  90 /**
  91  *      group - a group of config_items of a specific type, belonging
  92  *      to a specific subsystem.
  93  */
  94 struct config_group {
  95         struct config_item              cg_item;
  96         struct list_head                cg_children;
  97         struct configfs_subsystem       *cg_subsys;
  98         struct config_group             **default_groups;
  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                                         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 struct configfs_attribute {
 126         const char              *ca_name;
 127         struct module           *ca_owner;
 128         mode_t                  ca_mode;
 129 };
 130
 131 /*
 132  * Users often need to create attribute structures for their configurable
 133  * attributes, containing a configfs_attribute member and function pointers
 134  * for the show() and store() operations on that attribute. They can use
 135  * this macro (similar to sysfs' __ATTR) to make defining attributes easier.
 136  */
 137 #define __CONFIGFS_ATTR(_name, _mode, _show, _store)                    \
 138 {                                                                       \
 139         .attr   = {                                                     \
 140                         .ca_name = __stringify(_name),                  \
 141                         .ca_mode = _mode,                               \
 142                         .ca_owner = THIS_MODULE,                        \
 143         },                                                              \
 144         .show   = _show,                                                \
 145         .store  = _store,                                               \
 146 }
 147
 148 /*
 149  * If allow_link() exists, the item can symlink(2) out to other
 150  * items.  If the item is a group, it may support mkdir(2).
 151  * Groups supply one of make_group() and make_item().  If the
 152  * group supports make_group(), one can create group children.  If it
 153  * supports make_item(), one can create config_item children.  If it has
 154  * default_groups on group->default_groups, it has automatically created
 155  * group children.  default_groups may coexist alongsize make_group() or
 156  * make_item(), but if the group wishes to have only default_groups
 157  * children (disallowing mkdir(2)), it need not provide either function.
 158  * If the group has commit(), it supports pending and commited (active)
 159  * items.
 160  */
 161 struct configfs_item_operations {
 162         void (*release)(struct config_item *);
 163         ssize_t (*show_attribute)(struct config_item *, struct configfs_attribute *,char *);
 164         ssize_t (*store_attribute)(struct config_item *,struct configfs_attribute *,const char *, size_t);
 165         int (*allow_link)(struct config_item *src, struct config_item *target);
 166         int (*drop_link)(struct config_item *src, struct config_item *target);
 167 };
 168
 169 struct configfs_group_operations {
 170         struct config_item *(*make_item)(struct config_group *group, const char *name);
 171         struct config_group *(*make_group)(struct config_group *group, const char *name);
 172         int (*commit_item)(struct config_item *item);
 173         void (*disconnect_notify)(struct config_group *group, struct config_item *item);
 174         void (*drop_item)(struct config_group *group, struct config_item *item);
 175 };
 176
 177 struct configfs_subsystem {
 178         struct config_group     su_group;
 179         struct mutex            su_mutex;
 180 };
 181
 182 static inline struct configfs_subsystem *to_configfs_subsystem(struct config_group *group)
 183 {
 184         return group ?
 185                 container_of(group, struct configfs_subsystem, su_group) :
 186                 NULL;
 187 }
 188
 189 int configfs_register_subsystem(struct configfs_subsystem *subsys);
 190 void configfs_unregister_subsystem(struct configfs_subsystem *subsys);
 191
 192 /* These functions can sleep and can alloc with GFP_KERNEL */
 193 /* WARNING: These cannot be called underneath configfs callbacks!! */
 194 int configfs_depend_item(struct configfs_subsystem *subsys, struct config_item *target);
 195 void configfs_undepend_item(struct configfs_subsystem *subsys, struct config_item *target);
 196
 197 #endif  /* __KERNEL__ */
 198
 199 #endif /* _CONFIGFS_H_ */