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/stat.h>   /* S_IRUGO */
39 #include <linux/types.h>  /* ssize_t */
40 #include <linux/list.h>   /* struct list_head */
41 #include <linux/kref.h>   /* struct kref */
42 #include <linux/mutex.h>  /* struct mutex */
43 
44 #define CONFIGFS_ITEM_NAME_LEN	20
45 
46 struct module;
47 
48 struct configfs_item_operations;
49 struct configfs_group_operations;
50 struct configfs_attribute;
51 struct configfs_bin_attribute;
52 struct configfs_subsystem;
53 
54 struct config_item {
55 	char			*ci_name;
56 	char			ci_namebuf[CONFIGFS_ITEM_NAME_LEN];
57 	struct kref		ci_kref;
58 	struct list_head	ci_entry;
59 	struct config_item	*ci_parent;
60 	struct config_group	*ci_group;
61 	const struct config_item_type	*ci_type;
62 	struct dentry		*ci_dentry;
63 };
64 
65 extern __printf(2, 3)
66 int config_item_set_name(struct config_item *, const char *, ...);
67 
config_item_name(struct config_item * item)68 static inline char *config_item_name(struct config_item * item)
69 {
70 	return item->ci_name;
71 }
72 
73 extern void config_item_init_type_name(struct config_item *item,
74 				       const char *name,
75 				       const struct config_item_type *type);
76 
77 extern struct config_item *config_item_get(struct config_item *);
78 extern struct config_item *config_item_get_unless_zero(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 	struct configfs_bin_attribute		**ct_bin_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 list_head		default_groups;
98 	struct list_head		group_entry;
99 };
100 
101 extern void config_group_init(struct config_group *group);
102 extern void config_group_init_type_name(struct config_group *group,
103 					const char *name,
104 					const struct config_item_type *type);
105 
to_config_group(struct config_item * item)106 static inline struct config_group *to_config_group(struct config_item *item)
107 {
108 	return item ? container_of(item,struct config_group,cg_item) : NULL;
109 }
110 
config_group_get(struct config_group * group)111 static inline struct config_group *config_group_get(struct config_group *group)
112 {
113 	return group ? to_config_group(config_item_get(&group->cg_item)) : NULL;
114 }
115 
config_group_put(struct config_group * group)116 static inline void config_group_put(struct config_group *group)
117 {
118 	config_item_put(&group->cg_item);
119 }
120 
121 extern struct config_item *config_group_find_item(struct config_group *,
122 						  const char *);
123 
124 
configfs_add_default_group(struct config_group * new_group,struct config_group * group)125 static inline void configfs_add_default_group(struct config_group *new_group,
126 		struct config_group *group)
127 {
128 	list_add_tail(&new_group->group_entry, &group->default_groups);
129 }
130 
131 struct configfs_attribute {
132 	const char		*ca_name;
133 	struct module 		*ca_owner;
134 	umode_t			ca_mode;
135 	ssize_t (*show)(struct config_item *, char *);
136 	ssize_t (*store)(struct config_item *, const char *, size_t);
137 };
138 
139 #define CONFIGFS_ATTR(_pfx, _name)			\
140 static struct configfs_attribute _pfx##attr_##_name = {	\
141 	.ca_name	= __stringify(_name),		\
142 	.ca_mode	= S_IRUGO | S_IWUSR,		\
143 	.ca_owner	= THIS_MODULE,			\
144 	.show		= _pfx##_name##_show,		\
145 	.store		= _pfx##_name##_store,		\
146 }
147 
148 #define CONFIGFS_ATTR_RO(_pfx, _name)			\
149 static struct configfs_attribute _pfx##attr_##_name = {	\
150 	.ca_name	= __stringify(_name),		\
151 	.ca_mode	= S_IRUGO,			\
152 	.ca_owner	= THIS_MODULE,			\
153 	.show		= _pfx##_name##_show,		\
154 }
155 
156 #define CONFIGFS_ATTR_WO(_pfx, _name)			\
157 static struct configfs_attribute _pfx##attr_##_name = {	\
158 	.ca_name	= __stringify(_name),		\
159 	.ca_mode	= S_IWUSR,			\
160 	.ca_owner	= THIS_MODULE,			\
161 	.store		= _pfx##_name##_store,		\
162 }
163 
164 struct file;
165 struct vm_area_struct;
166 
167 struct configfs_bin_attribute {
168 	struct configfs_attribute cb_attr;	/* std. attribute */
169 	void *cb_private;			/* for user       */
170 	size_t cb_max_size;			/* max core size  */
171 	ssize_t (*read)(struct config_item *, void *, size_t);
172 	ssize_t (*write)(struct config_item *, const void *, size_t);
173 };
174 
175 #define CONFIGFS_BIN_ATTR(_pfx, _name, _priv, _maxsz)		\
176 static struct configfs_bin_attribute _pfx##attr_##_name = {	\
177 	.cb_attr = {						\
178 		.ca_name	= __stringify(_name),		\
179 		.ca_mode	= S_IRUGO | S_IWUSR,		\
180 		.ca_owner	= THIS_MODULE,			\
181 	},							\
182 	.cb_private	= _priv,				\
183 	.cb_max_size	= _maxsz,				\
184 	.read		= _pfx##_name##_read,			\
185 	.write		= _pfx##_name##_write,			\
186 }
187 
188 #define CONFIGFS_BIN_ATTR_RO(_pfx, _name, _priv, _maxsz)	\
189 static struct configfs_bin_attribute _pfx##attr_##_name = {	\
190 	.cb_attr = {						\
191 		.ca_name	= __stringify(_name),		\
192 		.ca_mode	= S_IRUGO,			\
193 		.ca_owner	= THIS_MODULE,			\
194 	},							\
195 	.cb_private	= _priv,				\
196 	.cb_max_size	= _maxsz,				\
197 	.read		= _pfx##_name##_read,			\
198 }
199 
200 #define CONFIGFS_BIN_ATTR_WO(_pfx, _name, _priv, _maxsz)	\
201 static struct configfs_bin_attribute _pfx##attr_##_name = {	\
202 	.cb_attr = {						\
203 		.ca_name	= __stringify(_name),		\
204 		.ca_mode	= S_IWUSR,			\
205 		.ca_owner	= THIS_MODULE,			\
206 	},							\
207 	.cb_private	= _priv,				\
208 	.cb_max_size	= _maxsz,				\
209 	.write		= _pfx##_name##_write,			\
210 }
211 
212 /*
213  * If allow_link() exists, the item can symlink(2) out to other
214  * items.  If the item is a group, it may support mkdir(2).
215  * Groups supply one of make_group() and make_item().  If the
216  * group supports make_group(), one can create group children.  If it
217  * supports make_item(), one can create config_item children.  make_group()
218  * and make_item() return ERR_PTR() on errors.  If it has
219  * default_groups on group->default_groups, it has automatically created
220  * group children.  default_groups may coexist alongsize make_group() or
221  * make_item(), but if the group wishes to have only default_groups
222  * children (disallowing mkdir(2)), it need not provide either function.
223  * If the group has commit(), it supports pending and committed (active)
224  * items.
225  */
226 struct configfs_item_operations {
227 	void (*release)(struct config_item *);
228 	int (*allow_link)(struct config_item *src, struct config_item *target);
229 	void (*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 int configfs_register_group(struct config_group *parent_group,
256 			    struct config_group *group);
257 void configfs_unregister_group(struct config_group *group);
258 
259 void configfs_remove_default_groups(struct config_group *group);
260 
261 struct config_group *
262 configfs_register_default_group(struct config_group *parent_group,
263 				const char *name,
264 				const struct config_item_type *item_type);
265 void configfs_unregister_default_group(struct config_group *group);
266 
267 /* These functions can sleep and can alloc with GFP_KERNEL */
268 /* WARNING: These cannot be called underneath configfs callbacks!! */
269 int configfs_depend_item(struct configfs_subsystem *subsys,
270 			 struct config_item *target);
271 void configfs_undepend_item(struct config_item *target);
272 
273 /*
274  * These functions can sleep and can alloc with GFP_KERNEL
275  * NOTE: These should be called only underneath configfs callbacks.
276  * NOTE: First parameter is a caller's subsystem, not target's.
277  * WARNING: These cannot be called on newly created item
278  *        (in make_group()/make_item() callback)
279  */
280 int configfs_depend_item_unlocked(struct configfs_subsystem *caller_subsys,
281 				  struct config_item *target);
282 
283 
configfs_undepend_item_unlocked(struct config_item * target)284 static inline void configfs_undepend_item_unlocked(struct config_item *target)
285 {
286 	configfs_undepend_item(target);
287 }
288 
289 #endif /* _CONFIGFS_H_ */
290