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 * Users often need to create attribute structures for their configurable 159 * attributes, containing a configfs_attribute member and function pointers 160 * for the show() and store() operations on that attribute. If they don't 161 * need anything else on the extended attribute structure, they can use 162 * this macro to define it The argument _item is the name of the 163 * config_item structure. 164 */ 165 #define CONFIGFS_ATTR_STRUCT(_item) \ 166 struct _item##_attribute { \ 167 struct configfs_attribute attr; \ 168 ssize_t (*show)(struct _item *, char *); \ 169 ssize_t (*store)(struct _item *, const char *, size_t); \ 170 } 171 172 /* 173 * With the extended attribute structure, users can use this macro 174 * (similar to sysfs' __ATTR) to make defining attributes easier. 175 * An example: 176 * #define MYITEM_ATTR(_name, _mode, _show, _store) \ 177 * struct myitem_attribute childless_attr_##_name = \ 178 * __CONFIGFS_ATTR(_name, _mode, _show, _store) 179 */ 180 #define __CONFIGFS_ATTR(_name, _mode, _show, _store) \ 181 { \ 182 .attr = { \ 183 .ca_name = __stringify(_name), \ 184 .ca_mode = _mode, \ 185 .ca_owner = THIS_MODULE, \ 186 }, \ 187 .show = _show, \ 188 .store = _store, \ 189 } 190 /* Here is a readonly version, only requiring a show() operation */ 191 #define __CONFIGFS_ATTR_RO(_name, _show) \ 192 { \ 193 .attr = { \ 194 .ca_name = __stringify(_name), \ 195 .ca_mode = 0444, \ 196 .ca_owner = THIS_MODULE, \ 197 }, \ 198 .show = _show, \ 199 } 200 201 /* 202 * With these extended attributes, the simple show_attribute() and 203 * store_attribute() operations need to call the show() and store() of the 204 * attributes. This is a common pattern, so we provide a macro to define 205 * them. The argument _item is the name of the config_item structure. 206 * This macro expects the attributes to be named "struct <name>_attribute" 207 * and the function to_<name>() to exist; 208 */ 209 #define CONFIGFS_ATTR_OPS(_item) \ 210 static ssize_t _item##_attr_show(struct config_item *item, \ 211 struct configfs_attribute *attr, \ 212 char *page) \ 213 { \ 214 struct _item *_item = to_##_item(item); \ 215 struct _item##_attribute *_item##_attr = \ 216 container_of(attr, struct _item##_attribute, attr); \ 217 ssize_t ret = 0; \ 218 \ 219 if (_item##_attr->show) \ 220 ret = _item##_attr->show(_item, page); \ 221 return ret; \ 222 } \ 223 static ssize_t _item##_attr_store(struct config_item *item, \ 224 struct configfs_attribute *attr, \ 225 const char *page, size_t count) \ 226 { \ 227 struct _item *_item = to_##_item(item); \ 228 struct _item##_attribute *_item##_attr = \ 229 container_of(attr, struct _item##_attribute, attr); \ 230 ssize_t ret = -EINVAL; \ 231 \ 232 if (_item##_attr->store) \ 233 ret = _item##_attr->store(_item, page, count); \ 234 return ret; \ 235 } 236 237 /* 238 * If allow_link() exists, the item can symlink(2) out to other 239 * items. If the item is a group, it may support mkdir(2). 240 * Groups supply one of make_group() and make_item(). If the 241 * group supports make_group(), one can create group children. If it 242 * supports make_item(), one can create config_item children. make_group() 243 * and make_item() return ERR_PTR() on errors. If it has 244 * default_groups on group->default_groups, it has automatically created 245 * group children. default_groups may coexist alongsize make_group() or 246 * make_item(), but if the group wishes to have only default_groups 247 * children (disallowing mkdir(2)), it need not provide either function. 248 * If the group has commit(), it supports pending and committed (active) 249 * items. 250 */ 251 struct configfs_item_operations { 252 void (*release)(struct config_item *); 253 ssize_t (*show_attribute)(struct config_item *, struct configfs_attribute *,char *); 254 ssize_t (*store_attribute)(struct config_item *,struct configfs_attribute *,const char *, size_t); 255 int (*allow_link)(struct config_item *src, struct config_item *target); 256 int (*drop_link)(struct config_item *src, struct config_item *target); 257 }; 258 259 struct configfs_group_operations { 260 struct config_item *(*make_item)(struct config_group *group, const char *name); 261 struct config_group *(*make_group)(struct config_group *group, const char *name); 262 int (*commit_item)(struct config_item *item); 263 void (*disconnect_notify)(struct config_group *group, struct config_item *item); 264 void (*drop_item)(struct config_group *group, struct config_item *item); 265 }; 266 267 struct configfs_subsystem { 268 struct config_group su_group; 269 struct mutex su_mutex; 270 }; 271 272 static inline struct configfs_subsystem *to_configfs_subsystem(struct config_group *group) 273 { 274 return group ? 275 container_of(group, struct configfs_subsystem, su_group) : 276 NULL; 277 } 278 279 int configfs_register_subsystem(struct configfs_subsystem *subsys); 280 void configfs_unregister_subsystem(struct configfs_subsystem *subsys); 281 282 /* These functions can sleep and can alloc with GFP_KERNEL */ 283 /* WARNING: These cannot be called underneath configfs callbacks!! */ 284 int configfs_depend_item(struct configfs_subsystem *subsys, struct config_item *target); 285 void configfs_undepend_item(struct configfs_subsystem *subsys, struct config_item *target); 286 287 #endif /* _CONFIGFS_H_ */ 288