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_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 __printf(2, 3)
  68 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_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         umode_t                 ca_mode;
 128         ssize_t (*show)(struct config_item *, char *);
 129         ssize_t (*store)(struct config_item *, const char *, size_t);
 130 };
 131
 132 #define CONFIGFS_ATTR(_pfx, _name)                      \
 133 static struct configfs_attribute _pfx##attr_##_name = { \
 134         .ca_name        = __stringify(_name),           \
 135         .ca_mode        = S_IRUGO | S_IWUSR,            \
 136         .ca_owner       = THIS_MODULE,                  \
 137         .show           = _pfx##_name##_show,           \
 138         .store          = _pfx##_name##_store,          \
 139 }
 140
 141 #define CONFIGFS_ATTR_RO(_pfx, _name)                   \
 142 static struct configfs_attribute _pfx##attr_##_name = { \
 143         .ca_name        = __stringify(_name),           \
 144         .ca_mode        = S_IRUGO,                      \
 145         .ca_owner       = THIS_MODULE,                  \
 146         .show           = _pfx##_name##_show,           \
 147 }
 148
 149 #define CONFIGFS_ATTR_WO(_pfx, _name)                   \
 150 static struct configfs_attribute _pfx##attr_##_name = { \
 151         .ca_name        = __stringify(_name),           \
 152         .ca_mode        = S_IWUSR,                      \
 153         .ca_owner       = THIS_MODULE,                  \
 154         .store          = _pfx##_name##_store,          \
 155 }
 156
 157 /*
 158  * If allow_link() exists, the item can symlink(2) out to other
 159  * items.  If the item is a group, it may support mkdir(2).
 160  * Groups supply one of make_group() and make_item().  If the
 161  * group supports make_group(), one can create group children.  If it
 162  * supports make_item(), one can create config_item children.  make_group()
 163  * and make_item() return ERR_PTR() on errors.  If it has
 164  * default_groups on group->default_groups, it has automatically created
 165  * group children.  default_groups may coexist alongsize make_group() or
 166  * make_item(), but if the group wishes to have only default_groups
 167  * children (disallowing mkdir(2)), it need not provide either function.
 168  * If the group has commit(), it supports pending and committed (active)
 169  * items.
 170  */
 171 struct configfs_item_operations {
 172         void (*release)(struct config_item *);
 173         int (*allow_link)(struct config_item *src, struct config_item *target);
 174         int (*drop_link)(struct config_item *src, struct config_item *target);
 175 };
 176
 177 struct configfs_group_operations {
 178         struct config_item *(*make_item)(struct config_group *group, const char *name);
 179         struct config_group *(*make_group)(struct config_group *group, const char *name);
 180         int (*commit_item)(struct config_item *item);
 181         void (*disconnect_notify)(struct config_group *group, struct config_item *item);
 182         void (*drop_item)(struct config_group *group, struct config_item *item);
 183 };
 184
 185 struct configfs_subsystem {
 186         struct config_group     su_group;
 187         struct mutex            su_mutex;
 188 };
 189
 190 static inline struct configfs_subsystem *to_configfs_subsystem(struct config_group *group)
 191 {
 192         return group ?
 193                 container_of(group, struct configfs_subsystem, su_group) :
 194                 NULL;
 195 }
 196
 197 int configfs_register_subsystem(struct configfs_subsystem *subsys);
 198 void configfs_unregister_subsystem(struct configfs_subsystem *subsys);
 199
 200 /* These functions can sleep and can alloc with GFP_KERNEL */
 201 /* WARNING: These cannot be called underneath configfs callbacks!! */
 202 int configfs_depend_item(struct configfs_subsystem *subsys, struct config_item *target);
 203 void configfs_undepend_item(struct configfs_subsystem *subsys, struct config_item *target);
 204
 205 #endif /* _CONFIGFS_H_ */