linux/include/linux/configfs.h
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   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
  49struct module;
  50
  51struct configfs_item_operations;
  52struct configfs_group_operations;
  53struct configfs_attribute;
  54struct configfs_subsystem;
  55
  56struct 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
  67extern int config_item_set_name(struct config_item *, const char *, ...);
  68
  69static inline char *config_item_name(struct config_item * item)
  70{
  71        return item->ci_name;
  72}
  73
  74extern void config_item_init(struct config_item *);
  75extern void config_item_init_type_name(struct config_item *item,
  76                                       const char *name,
  77                                       struct config_item_type *type);
  78
  79extern struct config_item * config_item_get(struct config_item *);
  80extern void config_item_put(struct config_item *);
  81
  82struct 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 */
  93struct 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
 100extern void config_group_init(struct config_group *group);
 101extern void config_group_init_type_name(struct config_group *group,
 102                                        const char *name,
 103                                        struct config_item_type *type);
 104
 105static 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
 110static 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
 115static inline void config_group_put(struct config_group *group)
 116{
 117        config_item_put(&group->cg_item);
 118}
 119
 120extern struct config_item *config_group_find_item(struct config_group *,
 121                                                  const char *);
 122
 123
 124struct configfs_attribute {
 125        const char              *ca_name;
 126        struct module           *ca_owner;
 127        umode_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)                                     \
 139struct _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)                                        \
 183static 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}                                                                       \
 196static 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 committed (active)
 222 * items.
 223 */
 224struct 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
 232struct 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
 240struct configfs_subsystem {
 241        struct config_group     su_group;
 242        struct mutex            su_mutex;
 243};
 244
 245static 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
 252int configfs_register_subsystem(struct configfs_subsystem *subsys);
 253void 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!! */
 257int configfs_depend_item(struct configfs_subsystem *subsys, struct config_item *target);
 258void configfs_undepend_item(struct configfs_subsystem *subsys, struct config_item *target);
 259
 260#endif /* _CONFIGFS_H_ */
 261
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