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
config_item_name(struct config_item * item)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
to_config_group(struct config_item * item)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
config_group_get(struct config_group * group)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
config_group_put(struct config_group * group)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 };
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
to_configfs_subsystem(struct config_group * group)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