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_bin_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 __printf(2, 3)
  69 int config_item_set_name(struct config_item *, const char *, ...);
  70
  71 static inline char *config_item_name(struct config_item * item)
  72 {
  73         return item->ci_name;
  74 }
  75
  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         struct configfs_bin_attribute           **ct_bin_attrs;
  89 };
  90
  91 /**
  92  *      group - a group of config_items of a specific type, belonging
  93  *      to a specific subsystem.
  94  */
  95 struct config_group {
  96         struct config_item              cg_item;
  97         struct list_head                cg_children;
  98         struct configfs_subsystem       *cg_subsys;
  99         struct config_group             **default_groups;
 100 };
 101
 102 extern void config_group_init(struct config_group *group);
 103 extern void config_group_init_type_name(struct config_group *group,
 104                                         const char *name,
 105                                         struct config_item_type *type);
 106
 107 static inline struct config_group *to_config_group(struct config_item *item)
 108 {
 109         return item ? container_of(item,struct config_group,cg_item) : NULL;
 110 }
 111
 112 static inline struct config_group *config_group_get(struct config_group *group)
 113 {
 114         return group ? to_config_group(config_item_get(&group->cg_item)) : NULL;
 115 }
 116
 117 static inline void config_group_put(struct config_group *group)
 118 {
 119         config_item_put(&group->cg_item);
 120 }
 121
 122 extern struct config_item *config_group_find_item(struct config_group *,
 123                                                   const char *);
 124
 125
 126 struct configfs_attribute {
 127         const char              *ca_name;
 128         struct module           *ca_owner;
 129         umode_t                 ca_mode;
 130         ssize_t (*show)(struct config_item *, char *);
 131         ssize_t (*store)(struct config_item *, const char *, size_t);
 132 };
 133
 134 #define CONFIGFS_ATTR(_pfx, _name)                      \
 135 static struct configfs_attribute _pfx##attr_##_name = { \
 136         .ca_name        = __stringify(_name),           \
 137         .ca_mode        = S_IRUGO | S_IWUSR,            \
 138         .ca_owner       = THIS_MODULE,                  \
 139         .show           = _pfx##_name##_show,           \
 140         .store          = _pfx##_name##_store,          \
 141 }
 142
 143 #define CONFIGFS_ATTR_RO(_pfx, _name)                   \
 144 static struct configfs_attribute _pfx##attr_##_name = { \
 145         .ca_name        = __stringify(_name),           \
 146         .ca_mode        = S_IRUGO,                      \
 147         .ca_owner       = THIS_MODULE,                  \
 148         .show           = _pfx##_name##_show,           \
 149 }
 150
 151 #define CONFIGFS_ATTR_WO(_pfx, _name)                   \
 152 static struct configfs_attribute _pfx##attr_##_name = { \
 153         .ca_name        = __stringify(_name),           \
 154         .ca_mode        = S_IWUSR,                      \
 155         .ca_owner       = THIS_MODULE,                  \
 156         .store          = _pfx##_name##_store,          \
 157 }
 158
 159 struct file;
 160 struct vm_area_struct;
 161
 162 struct configfs_bin_attribute {
 163         struct configfs_attribute cb_attr;      /* std. attribute */
 164         void *cb_private;                       /* for user       */
 165         size_t cb_max_size;                     /* max core size  */
 166         ssize_t (*read)(struct config_item *, void *, size_t);
 167         ssize_t (*write)(struct config_item *, const void *, size_t);
 168 };
 169
 170 #define CONFIGFS_BIN_ATTR(_pfx, _name, _priv, _maxsz)           \
 171 static struct configfs_bin_attribute _pfx##attr_##_name = {     \
 172         .cb_attr = {                                            \
 173                 .ca_name        = __stringify(_name),           \
 174                 .ca_mode        = S_IRUGO | S_IWUSR,            \
 175                 .ca_owner       = THIS_MODULE,                  \
 176         },                                                      \
 177         .cb_private     = _priv,                                \
 178         .cb_max_size    = _maxsz,                               \
 179         .read           = _pfx##_name##_read,                   \
 180         .write          = _pfx##_name##_write,                  \
 181 }
 182
 183 #define CONFIGFS_BIN_ATTR_RO(_pfx, _name, _priv, _maxsz)        \
 184 static struct configfs_attribute _pfx##attr_##_name = {         \
 185         .cb_attr = {                                            \
 186                 .ca_name        = __stringify(_name),           \
 187                 .ca_mode        = S_IRUGO,                      \
 188                 .ca_owner       = THIS_MODULE,                  \
 189         },                                                      \
 190         .cb_private     = _priv,                                \
 191         .cb_max_size    = _maxsz,                               \
 192         .read           = _pfx##_name##_read,                   \
 193 }
 194
 195 #define CONFIGFS_BIN_ATTR_WO(_pfx, _name, _priv, _maxsz)        \
 196 static struct configfs_attribute _pfx##attr_##_name = {         \
 197         .cb_attr = {                                            \
 198                 .ca_name        = __stringify(_name),           \
 199                 .ca_mode        = S_IWUSR,                      \
 200                 .ca_owner       = THIS_MODULE,                  \
 201         },                                                      \
 202         .cb_private     = _priv,                                \
 203         .cb_max_size    = _maxsz,                               \
 204         .write          = _pfx##_name##_write,                  \
 205 }
 206
 207 /*
 208  * If allow_link() exists, the item can symlink(2) out to other
 209  * items.  If the item is a group, it may support mkdir(2).
 210  * Groups supply one of make_group() and make_item().  If the
 211  * group supports make_group(), one can create group children.  If it
 212  * supports make_item(), one can create config_item children.  make_group()
 213  * and make_item() return ERR_PTR() on errors.  If it has
 214  * default_groups on group->default_groups, it has automatically created
 215  * group children.  default_groups may coexist alongsize make_group() or
 216  * make_item(), but if the group wishes to have only default_groups
 217  * children (disallowing mkdir(2)), it need not provide either function.
 218  * If the group has commit(), it supports pending and committed (active)
 219  * items.
 220  */
 221 struct configfs_item_operations {
 222         void (*release)(struct config_item *);
 223         int (*allow_link)(struct config_item *src, struct config_item *target);
 224         int (*drop_link)(struct config_item *src, struct config_item *target);
 225 };
 226
 227 struct configfs_group_operations {
 228         struct config_item *(*make_item)(struct config_group *group, const char *name);
 229         struct config_group *(*make_group)(struct config_group *group, const char *name);
 230         int (*commit_item)(struct config_item *item);
 231         void (*disconnect_notify)(struct config_group *group, struct config_item *item);
 232         void (*drop_item)(struct config_group *group, struct config_item *item);
 233 };
 234
 235 struct configfs_subsystem {
 236         struct config_group     su_group;
 237         struct mutex            su_mutex;
 238 };
 239
 240 static inline struct configfs_subsystem *to_configfs_subsystem(struct config_group *group)
 241 {
 242         return group ?
 243                 container_of(group, struct configfs_subsystem, su_group) :
 244                 NULL;
 245 }
 246
 247 int configfs_register_subsystem(struct configfs_subsystem *subsys);
 248 void configfs_unregister_subsystem(struct configfs_subsystem *subsys);
 249
 250 int configfs_register_group(struct config_group *parent_group,
 251                             struct config_group *group);
 252 void configfs_unregister_group(struct config_group *group);
 253
 254 struct config_group *
 255 configfs_register_default_group(struct config_group *parent_group,
 256                                 const char *name,
 257                                 struct config_item_type *item_type);
 258 void configfs_unregister_default_group(struct config_group *group);
 259
 260 /* These functions can sleep and can alloc with GFP_KERNEL */
 261 /* WARNING: These cannot be called underneath configfs callbacks!! */
 262 int configfs_depend_item(struct configfs_subsystem *subsys,
 263                          struct config_item *target);
 264 void configfs_undepend_item(struct config_item *target);
 265
 266 /*
 267  * These functions can sleep and can alloc with GFP_KERNEL
 268  * NOTE: These should be called only underneath configfs callbacks.
 269  * NOTE: First parameter is a caller's subsystem, not target's.
 270  * WARNING: These cannot be called on newly created item
 271  *        (in make_group()/make_item() callback)
 272  */
 273 int configfs_depend_item_unlocked(struct configfs_subsystem *caller_subsys,
 274                                   struct config_item *target);
 275
 276
 277 static inline void configfs_undepend_item_unlocked(struct config_item *target)
 278 {
 279         configfs_undepend_item(target);
 280 }
 281
 282 #endif /* _CONFIGFS_H_ */