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