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/types.h>
  41 #include <linux/list.h>
  42 #include <linux/kref.h>
  43
  44 #include <asm/atomic.h>
  45 #include <asm/semaphore.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 extern void config_item_cleanup(struct config_item *);
  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 /**
  92  *      group - a group of config_items of a specific type, belonging
  93  *      to a specific subsystem.
  94  */
  95
  96 struct config_group {
  97         struct config_item              cg_item;
  98         struct list_head                cg_children;
  99         struct configfs_subsystem       *cg_subsys;
 100         struct config_group             **default_groups;
 101 };
 102
 103
 104 extern void config_group_init(struct config_group *group);
 105 extern void config_group_init_type_name(struct config_group *group,
 106                                         const char *name,
 107                                         struct config_item_type *type);
 108
 109
 110 static inline struct config_group *to_config_group(struct config_item *item)
 111 {
 112         return item ? container_of(item,struct config_group,cg_item) : NULL;
 113 }
 114
 115 static inline struct config_group *config_group_get(struct config_group *group)
 116 {
 117         return group ? to_config_group(config_item_get(&group->cg_item)) : NULL;
 118 }
 119
 120 static inline void config_group_put(struct config_group *group)
 121 {
 122         config_item_put(&group->cg_item);
 123 }
 124
 125 extern struct config_item *config_group_find_obj(struct config_group *, const char *);
 126
 127
 128 struct configfs_attribute {
 129         const char              *ca_name;
 130         struct module           *ca_owner;
 131         mode_t                  ca_mode;
 132 };
 133
 134
 135 /*
 136  * If allow_link() exists, the item can symlink(2) out to other
 137  * items.  If the item is a group, it may support mkdir(2).
 138  * Groups supply one of make_group() and make_item().  If the
 139  * group supports make_group(), one can create group children.  If it
 140  * supports make_item(), one can create config_item children.  If it has
 141  * default_groups on group->default_groups, it has automatically created
 142  * group children.  default_groups may coexist alongsize make_group() or
 143  * make_item(), but if the group wishes to have only default_groups
 144  * children (disallowing mkdir(2)), it need not provide either function.
 145  * If the group has commit(), it supports pending and commited (active)
 146  * items.
 147  */
 148 struct configfs_item_operations {
 149         void (*release)(struct config_item *);
 150         ssize_t (*show_attribute)(struct config_item *, struct configfs_attribute *,char *);
 151         ssize_t (*store_attribute)(struct config_item *,struct configfs_attribute *,const char *, size_t);
 152         int (*allow_link)(struct config_item *src, struct config_item *target);
 153         int (*drop_link)(struct config_item *src, struct config_item *target);
 154 };
 155
 156 struct configfs_group_operations {
 157         struct config_item *(*make_item)(struct config_group *group, const char *name);
 158         struct config_group *(*make_group)(struct config_group *group, const char *name);
 159         int (*commit_item)(struct config_item *item);
 160         void (*drop_item)(struct config_group *group, struct config_item *item);
 161 };
 162
 163
 164
 165 /**
 166  * Use these macros to make defining attributes easier. See include/linux/device.h
 167  * for examples..
 168  */
 169
 170 #if 0
 171 #define __ATTR(_name,_mode,_show,_store) { \
 172         .attr = {.ca_name = __stringify(_name), .ca_mode = _mode, .ca_owner = THIS_MODULE },    \
 173         .show   = _show,                                        \
 174         .store  = _store,                                       \
 175 }
 176
 177 #define __ATTR_RO(_name) { \
 178         .attr   = { .ca_name = __stringify(_name), .ca_mode = 0444, .ca_owner = THIS_MODULE },  \
 179         .show   = _name##_show, \
 180 }
 181
 182 #define __ATTR_NULL { .attr = { .name = NULL } }
 183
 184 #define attr_name(_attr) (_attr).attr.name
 185 #endif
 186
 187
 188 struct configfs_subsystem {
 189         struct config_group     su_group;
 190         struct semaphore        su_sem;
 191 };
 192
 193 static inline struct configfs_subsystem *to_configfs_subsystem(struct config_group *group)
 194 {
 195         return group ?
 196                 container_of(group, struct configfs_subsystem, su_group) :
 197                 NULL;
 198 }
 199
 200 int configfs_register_subsystem(struct configfs_subsystem *subsys);
 201 void configfs_unregister_subsystem(struct configfs_subsystem *subsys);
 202
 203 #endif  /* __KERNEL__ */
 204
 205 #endif /* _CONFIGFS_H_ */