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 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 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 mode_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) \ 139 struct _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) \ 183 static 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 } \ 196 static 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 */ 224 struct 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 }; 231 232 struct 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 }; 239 240 struct configfs_subsystem { 241 struct config_group su_group; 242 struct mutex su_mutex; 243 }; 244 245 static 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 } 251 252 int configfs_register_subsystem(struct configfs_subsystem *subsys); 253 void 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!! */ 257 int configfs_depend_item(struct configfs_subsystem *subsys, struct config_item *target); 258 void configfs_undepend_item(struct configfs_subsystem *subsys, struct config_item *target); 259 260 #endif /* _CONFIGFS_H_ */ 261