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configfs.h
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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 
53 struct configfs_attribute;
54 struct configfs_subsystem;
55 
56 struct config_item {
57  char *ci_name;
59  struct kref ci_kref;
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 
83  struct module *ct_owner;
87 };
88 
93 struct config_group {
98 };
99 
100 extern void config_group_init(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 
125  const char *ca_name;
126  struct module *ca_owner;
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  */
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);
230 };
231 
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);
238 };
239 
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 
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_ */