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 #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
  44 #include <asm/atomic.h>
  45
  46 #define CONFIGFS_ITEM_NAME_LEN  20
  47
  48 struct module;
  49
  50 struct configfs_item_operations;
  51 struct configfs_group_operations;
  52 struct configfs_attribute;
  53 struct configfs_subsystem;
  54
  55 struct config_item {
  56         char                    *ci_name;
  57         char                    ci_namebuf[CONFIGFS_ITEM_NAME_LEN];
  58         struct kref             ci_kref;
  59         struct list_head        ci_entry;
  60         struct config_item      *ci_parent;
  61         struct config_group     *ci_group;
  62         struct config_item_type *ci_type;
  63         struct dentry           *ci_dentry;
  64 };
  65
  66 extern 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(struct config_item *);
  74 extern void config_item_init_type_name(struct config_item *item,
  75                                        const char *name,
  76                                        struct config_item_type *type);
  77
  78 extern struct config_item * config_item_get(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 };
  87
  88 /**
  89  *      group - a group of config_items of a specific type, belonging
  90  *      to a specific subsystem.
  91  */
  92 struct config_group {
  93         struct config_item              cg_item;
  94         struct list_head                cg_children;
  95         struct configfs_subsystem       *cg_subsys;
  96         struct config_group             **default_groups;
  97 };
  98
  99 extern void config_group_init(struct config_group *group);
 100 extern void config_group_init_type_name(struct config_group *group,
 101                                         const char *name,
 102                                         struct config_item_type *type);
 103
 104 static inline struct config_group *to_config_group(struct config_item *item)
 105 {
 106         return item ? container_of(item,struct config_group,cg_item) : NULL;
 107 }
 108
 109 static inline struct config_group *config_group_get(struct config_group *group)
 110 {
 111         return group ? to_config_group(config_item_get(&group->cg_item)) : NULL;
 112 }
 113
 114 static inline void config_group_put(struct config_group *group)
 115 {
 116         config_item_put(&group->cg_item);
 117 }
 118
 119 extern struct config_item *config_group_find_item(struct config_group *,
 120                                                   const char *);
 121
 122
 123 struct configfs_attribute {
 124         const char              *ca_name;
 125         struct module           *ca_owner;
 126         mode_t                  ca_mode;
 127 };
 128
 129 /*
 130  * Users often need to create attribute structures for their configurable
 131  * attributes, containing a configfs_attribute member and function pointers
 132  * for the show() and store() operations on that attribute. They can use
 133  * this macro (similar to sysfs' __ATTR) to make defining attributes easier.
 134  */
 135 #define __CONFIGFS_ATTR(_name, _mode, _show, _store)                    \
 136 {                                                                       \
 137         .attr   = {                                                     \
 138                         .ca_name = __stringify(_name),                  \
 139                         .ca_mode = _mode,                               \
 140                         .ca_owner = THIS_MODULE,                        \
 141         },                                                              \
 142         .show   = _show,                                                \
 143         .store  = _store,                                               \
 144 }
 145
 146 /*
 147  * If allow_link() exists, the item can symlink(2) out to other
 148  * items.  If the item is a group, it may support mkdir(2).
 149  * Groups supply one of make_group() and make_item().  If the
 150  * group supports make_group(), one can create group children.  If it
 151  * supports make_item(), one can create config_item children.  make_group()
 152  * and make_item() return ERR_PTR() on errors.  If it has
 153  * default_groups on group->default_groups, it has automatically created
 154  * group children.  default_groups may coexist alongsize make_group() or
 155  * make_item(), but if the group wishes to have only default_groups
 156  * children (disallowing mkdir(2)), it need not provide either function.
 157  * If the group has commit(), it supports pending and commited (active)
 158  * items.
 159  */
 160 struct configfs_item_operations {
 161         void (*release)(struct config_item *);
 162         ssize_t (*show_attribute)(struct config_item *, struct configfs_attribute *,char *);
 163         ssize_t (*store_attribute)(struct config_item *,struct configfs_attribute *,const char *, size_t);
 164         int (*allow_link)(struct config_item *src, struct config_item *target);
 165         int (*drop_link)(struct config_item *src, struct config_item *target);
 166 };
 167
 168 struct configfs_group_operations {
 169         struct config_item *(*make_item)(struct config_group *group, const char *name);
 170         struct config_group *(*make_group)(struct config_group *group, const char *name);
 171         int (*commit_item)(struct config_item *item);
 172         void (*disconnect_notify)(struct config_group *group, struct config_item *item);
 173         void (*drop_item)(struct config_group *group, struct config_item *item);
 174 };
 175
 176 struct configfs_subsystem {
 177         struct config_group     su_group;
 178         struct mutex            su_mutex;
 179 };
 180
 181 static inline struct configfs_subsystem *to_configfs_subsystem(struct config_group *group)
 182 {
 183         return group ?
 184                 container_of(group, struct configfs_subsystem, su_group) :
 185                 NULL;
 186 }
 187
 188 int configfs_register_subsystem(struct configfs_subsystem *subsys);
 189 void configfs_unregister_subsystem(struct configfs_subsystem *subsys);
 190
 191 /* These functions can sleep and can alloc with GFP_KERNEL */
 192 /* WARNING: These cannot be called underneath configfs callbacks!! */
 193 int configfs_depend_item(struct configfs_subsystem *subsys, struct config_item *target);
 194 void configfs_undepend_item(struct configfs_subsystem *subsys, struct config_item *target);
 195
 196 #endif /* _CONFIGFS_H_ */