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_type_name(struct config_item *item, 75 const char *name, 76 struct config_item_type *type); 77 78 extern struct config_item * config_item_get(struct config_item *); 79 extern void config_item_put(struct config_item *); 80 81 struct config_item_type { 82 struct module *ct_owner; 83 struct configfs_item_operations *ct_item_ops; 84 struct configfs_group_operations *ct_group_ops; 85 struct configfs_attribute **ct_attrs; 86 }; 87 88 /** 89 * group - a group of config_items of a specific type, belonging 90 * to a specific subsystem. 91 */ 92 struct config_group { 93 struct config_item cg_item; 94 struct list_head cg_children; 95 struct configfs_subsystem *cg_subsys; 96 struct config_group **default_groups; 97 }; 98 99 extern void config_group_init(struct config_group *group); 100 extern void config_group_init_type_name(struct config_group *group, 101 const char *name, 102 struct config_item_type *type); 103 104 static inline struct config_group *to_config_group(struct config_item *item) 105 { 106 return item ? container_of(item,struct config_group,cg_item) : NULL; 107 } 108 109 static inline struct config_group *config_group_get(struct config_group *group) 110 { 111 return group ? to_config_group(config_item_get(&group->cg_item)) : NULL; 112 } 113 114 static inline void config_group_put(struct config_group *group) 115 { 116 config_item_put(&group->cg_item); 117 } 118 119 extern struct config_item *config_group_find_item(struct config_group *, 120 const char *); 121 122 123 struct configfs_attribute { 124 const char *ca_name; 125 struct module *ca_owner; 126 umode_t ca_mode; 127 }; 128 129 /* 130 * Users often need to create attribute structures for their configurable 131 * attributes, containing a configfs_attribute member and function pointers 132 * for the show() and store() operations on that attribute. If they don't 133 * need anything else on the extended attribute structure, they can use 134 * this macro to define it The argument _item is the name of the 135 * config_item structure. 136 */ 137 #define CONFIGFS_ATTR_STRUCT(_item) \ 138 struct _item##_attribute { \ 139 struct configfs_attribute attr; \ 140 ssize_t (*show)(struct _item *, char *); \ 141 ssize_t (*store)(struct _item *, const char *, size_t); \ 142 } 143 144 /* 145 * With the extended attribute structure, users can use this macro 146 * (similar to sysfs' __ATTR) to make defining attributes easier. 147 * An example: 148 * #define MYITEM_ATTR(_name, _mode, _show, _store) \ 149 * struct myitem_attribute childless_attr_##_name = \ 150 * __CONFIGFS_ATTR(_name, _mode, _show, _store) 151 */ 152 #define __CONFIGFS_ATTR(_name, _mode, _show, _store) \ 153 { \ 154 .attr = { \ 155 .ca_name = __stringify(_name), \ 156 .ca_mode = _mode, \ 157 .ca_owner = THIS_MODULE, \ 158 }, \ 159 .show = _show, \ 160 .store = _store, \ 161 } 162 /* Here is a readonly version, only requiring a show() operation */ 163 #define __CONFIGFS_ATTR_RO(_name, _show) \ 164 { \ 165 .attr = { \ 166 .ca_name = __stringify(_name), \ 167 .ca_mode = 0444, \ 168 .ca_owner = THIS_MODULE, \ 169 }, \ 170 .show = _show, \ 171 } 172 173 /* 174 * With these extended attributes, the simple show_attribute() and 175 * store_attribute() operations need to call the show() and store() of the 176 * attributes. This is a common pattern, so we provide a macro to define 177 * them. The argument _item is the name of the config_item structure. 178 * This macro expects the attributes to be named "struct <name>_attribute" 179 * and the function to_<name>() to exist; 180 */ 181 #define CONFIGFS_ATTR_OPS(_item) \ 182 static ssize_t _item##_attr_show(struct config_item *item, \ 183 struct configfs_attribute *attr, \ 184 char *page) \ 185 { \ 186 struct _item *_item = to_##_item(item); \ 187 struct _item##_attribute *_item##_attr = \ 188 container_of(attr, struct _item##_attribute, attr); \ 189 ssize_t ret = 0; \ 190 \ 191 if (_item##_attr->show) \ 192 ret = _item##_attr->show(_item, page); \ 193 return ret; \ 194 } \ 195 static ssize_t _item##_attr_store(struct config_item *item, \ 196 struct configfs_attribute *attr, \ 197 const char *page, size_t count) \ 198 { \ 199 struct _item *_item = to_##_item(item); \ 200 struct _item##_attribute *_item##_attr = \ 201 container_of(attr, struct _item##_attribute, attr); \ 202 ssize_t ret = -EINVAL; \ 203 \ 204 if (_item##_attr->store) \ 205 ret = _item##_attr->store(_item, page, count); \ 206 return ret; \ 207 } 208 209 /* 210 * If allow_link() exists, the item can symlink(2) out to other 211 * items. If the item is a group, it may support mkdir(2). 212 * Groups supply one of make_group() and make_item(). If the 213 * group supports make_group(), one can create group children. If it 214 * supports make_item(), one can create config_item children. make_group() 215 * and make_item() return ERR_PTR() on errors. If it has 216 * default_groups on group->default_groups, it has automatically created 217 * group children. default_groups may coexist alongsize make_group() or 218 * make_item(), but if the group wishes to have only default_groups 219 * children (disallowing mkdir(2)), it need not provide either function. 220 * If the group has commit(), it supports pending and committed (active) 221 * items. 222 */ 223 struct configfs_item_operations { 224 void (*release)(struct config_item *); 225 ssize_t (*show_attribute)(struct config_item *, struct configfs_attribute *,char *); 226 ssize_t (*store_attribute)(struct config_item *,struct configfs_attribute *,const char *, size_t); 227 int (*allow_link)(struct config_item *src, struct config_item *target); 228 int (*drop_link)(struct config_item *src, struct config_item *target); 229 }; 230 231 struct configfs_group_operations { 232 struct config_item *(*make_item)(struct config_group *group, const char *name); 233 struct config_group *(*make_group)(struct config_group *group, const char *name); 234 int (*commit_item)(struct config_item *item); 235 void (*disconnect_notify)(struct config_group *group, struct config_item *item); 236 void (*drop_item)(struct config_group *group, struct config_item *item); 237 }; 238 239 struct configfs_subsystem { 240 struct config_group su_group; 241 struct mutex su_mutex; 242 }; 243 244 static inline struct configfs_subsystem *to_configfs_subsystem(struct config_group *group) 245 { 246 return group ? 247 container_of(group, struct configfs_subsystem, su_group) : 248 NULL; 249 } 250 251 int configfs_register_subsystem(struct configfs_subsystem *subsys); 252 void configfs_unregister_subsystem(struct configfs_subsystem *subsys); 253 254 /* These functions can sleep and can alloc with GFP_KERNEL */ 255 /* WARNING: These cannot be called underneath configfs callbacks!! */ 256 int configfs_depend_item(struct configfs_subsystem *subsys, struct config_item *target); 257 void configfs_undepend_item(struct configfs_subsystem *subsys, struct config_item *target); 258 259 #endif /* _CONFIGFS_H_ */ 260