1 /* SPDX-License-Identifier: GPL-2.0-or-later */
2 /*
3  * configfs.h - definitions for the device driver filesystem
4  *
5  * Based on sysfs:
6  * 	sysfs is Copyright (C) 2001, 2002, 2003 Patrick Mochel
7  *
8  * Based on kobject.h:
9  *      Copyright (c) 2002-2003	Patrick Mochel
10  *      Copyright (c) 2002-2003	Open Source Development Labs
11  *
12  * configfs Copyright (C) 2005 Oracle.  All rights reserved.
13  *
14  * Please read Documentation/filesystems/configfs.rst before using
15  * the configfs interface, ESPECIALLY the parts about reference counts and
16  * item destructors.
17  */
18 
19 #ifndef _CONFIGFS_H_
20 #define _CONFIGFS_H_
21 
22 #include <linux/stat.h>   /* S_IRUGO */
23 #include <linux/types.h>  /* ssize_t */
24 #include <linux/list.h>   /* struct list_head */
25 #include <linux/kref.h>   /* struct kref */
26 #include <linux/mutex.h>  /* struct mutex */
27 
28 #define CONFIGFS_ITEM_NAME_LEN	20
29 
30 struct module;
31 
32 struct configfs_item_operations;
33 struct configfs_group_operations;
34 struct configfs_attribute;
35 struct configfs_bin_attribute;
36 struct configfs_subsystem;
37 
38 struct config_item {
39 	char			*ci_name;
40 	char			ci_namebuf[CONFIGFS_ITEM_NAME_LEN];
41 	struct kref		ci_kref;
42 	struct list_head	ci_entry;
43 	struct config_item	*ci_parent;
44 	struct config_group	*ci_group;
45 	const struct config_item_type	*ci_type;
46 	struct dentry		*ci_dentry;
47 };
48 
49 extern __printf(2, 3)
50 int config_item_set_name(struct config_item *, const char *, ...);
51 
config_item_name(struct config_item * item)52 static inline char *config_item_name(struct config_item * item)
53 {
54 	return item->ci_name;
55 }
56 
57 extern void config_item_init_type_name(struct config_item *item,
58 				       const char *name,
59 				       const struct config_item_type *type);
60 
61 extern struct config_item *config_item_get(struct config_item *);
62 extern struct config_item *config_item_get_unless_zero(struct config_item *);
63 extern void config_item_put(struct config_item *);
64 
65 struct config_item_type {
66 	struct module				*ct_owner;
67 	struct configfs_item_operations		*ct_item_ops;
68 	struct configfs_group_operations	*ct_group_ops;
69 	struct configfs_attribute		**ct_attrs;
70 	struct configfs_bin_attribute		**ct_bin_attrs;
71 };
72 
73 /**
74  *	group - a group of config_items of a specific type, belonging
75  *	to a specific subsystem.
76  */
77 struct config_group {
78 	struct config_item		cg_item;
79 	struct list_head		cg_children;
80 	struct configfs_subsystem 	*cg_subsys;
81 	struct list_head		default_groups;
82 	struct list_head		group_entry;
83 };
84 
85 extern void config_group_init(struct config_group *group);
86 extern void config_group_init_type_name(struct config_group *group,
87 					const char *name,
88 					const struct config_item_type *type);
89 
to_config_group(struct config_item * item)90 static inline struct config_group *to_config_group(struct config_item *item)
91 {
92 	return item ? container_of(item,struct config_group,cg_item) : NULL;
93 }
94 
config_group_get(struct config_group * group)95 static inline struct config_group *config_group_get(struct config_group *group)
96 {
97 	return group ? to_config_group(config_item_get(&group->cg_item)) : NULL;
98 }
99 
config_group_put(struct config_group * group)100 static inline void config_group_put(struct config_group *group)
101 {
102 	config_item_put(&group->cg_item);
103 }
104 
105 extern struct config_item *config_group_find_item(struct config_group *,
106 						  const char *);
107 
108 
configfs_add_default_group(struct config_group * new_group,struct config_group * group)109 static inline void configfs_add_default_group(struct config_group *new_group,
110 		struct config_group *group)
111 {
112 	list_add_tail(&new_group->group_entry, &group->default_groups);
113 }
114 
115 struct configfs_attribute {
116 	const char		*ca_name;
117 	struct module 		*ca_owner;
118 	umode_t			ca_mode;
119 	ssize_t (*show)(struct config_item *, char *);
120 	ssize_t (*store)(struct config_item *, const char *, size_t);
121 };
122 
123 #define CONFIGFS_ATTR(_pfx, _name)			\
124 static struct configfs_attribute _pfx##attr_##_name = {	\
125 	.ca_name	= __stringify(_name),		\
126 	.ca_mode	= S_IRUGO | S_IWUSR,		\
127 	.ca_owner	= THIS_MODULE,			\
128 	.show		= _pfx##_name##_show,		\
129 	.store		= _pfx##_name##_store,		\
130 }
131 
132 #define CONFIGFS_ATTR_RO(_pfx, _name)			\
133 static struct configfs_attribute _pfx##attr_##_name = {	\
134 	.ca_name	= __stringify(_name),		\
135 	.ca_mode	= S_IRUGO,			\
136 	.ca_owner	= THIS_MODULE,			\
137 	.show		= _pfx##_name##_show,		\
138 }
139 
140 #define CONFIGFS_ATTR_WO(_pfx, _name)			\
141 static struct configfs_attribute _pfx##attr_##_name = {	\
142 	.ca_name	= __stringify(_name),		\
143 	.ca_mode	= S_IWUSR,			\
144 	.ca_owner	= THIS_MODULE,			\
145 	.store		= _pfx##_name##_store,		\
146 }
147 
148 struct file;
149 struct vm_area_struct;
150 
151 struct configfs_bin_attribute {
152 	struct configfs_attribute cb_attr;	/* std. attribute */
153 	void *cb_private;			/* for user       */
154 	size_t cb_max_size;			/* max core size  */
155 	ssize_t (*read)(struct config_item *, void *, size_t);
156 	ssize_t (*write)(struct config_item *, const void *, size_t);
157 };
158 
159 #define CONFIGFS_BIN_ATTR(_pfx, _name, _priv, _maxsz)		\
160 static struct configfs_bin_attribute _pfx##attr_##_name = {	\
161 	.cb_attr = {						\
162 		.ca_name	= __stringify(_name),		\
163 		.ca_mode	= S_IRUGO | S_IWUSR,		\
164 		.ca_owner	= THIS_MODULE,			\
165 	},							\
166 	.cb_private	= _priv,				\
167 	.cb_max_size	= _maxsz,				\
168 	.read		= _pfx##_name##_read,			\
169 	.write		= _pfx##_name##_write,			\
170 }
171 
172 #define CONFIGFS_BIN_ATTR_RO(_pfx, _name, _priv, _maxsz)	\
173 static struct configfs_bin_attribute _pfx##attr_##_name = {	\
174 	.cb_attr = {						\
175 		.ca_name	= __stringify(_name),		\
176 		.ca_mode	= S_IRUGO,			\
177 		.ca_owner	= THIS_MODULE,			\
178 	},							\
179 	.cb_private	= _priv,				\
180 	.cb_max_size	= _maxsz,				\
181 	.read		= _pfx##_name##_read,			\
182 }
183 
184 #define CONFIGFS_BIN_ATTR_WO(_pfx, _name, _priv, _maxsz)	\
185 static struct configfs_bin_attribute _pfx##attr_##_name = {	\
186 	.cb_attr = {						\
187 		.ca_name	= __stringify(_name),		\
188 		.ca_mode	= S_IWUSR,			\
189 		.ca_owner	= THIS_MODULE,			\
190 	},							\
191 	.cb_private	= _priv,				\
192 	.cb_max_size	= _maxsz,				\
193 	.write		= _pfx##_name##_write,			\
194 }
195 
196 /*
197  * If allow_link() exists, the item can symlink(2) out to other
198  * items.  If the item is a group, it may support mkdir(2).
199  * Groups supply one of make_group() and make_item().  If the
200  * group supports make_group(), one can create group children.  If it
201  * supports make_item(), one can create config_item children.  make_group()
202  * and make_item() return ERR_PTR() on errors.  If it has
203  * default_groups on group->default_groups, it has automatically created
204  * group children.  default_groups may coexist alongsize make_group() or
205  * make_item(), but if the group wishes to have only default_groups
206  * children (disallowing mkdir(2)), it need not provide either function.
207  * If the group has commit(), it supports pending and committed (active)
208  * items.
209  */
210 struct configfs_item_operations {
211 	void (*release)(struct config_item *);
212 	int (*allow_link)(struct config_item *src, struct config_item *target);
213 	void (*drop_link)(struct config_item *src, struct config_item *target);
214 };
215 
216 struct configfs_group_operations {
217 	struct config_item *(*make_item)(struct config_group *group, const char *name);
218 	struct config_group *(*make_group)(struct config_group *group, const char *name);
219 	int (*commit_item)(struct config_item *item);
220 	void (*disconnect_notify)(struct config_group *group, struct config_item *item);
221 	void (*drop_item)(struct config_group *group, struct config_item *item);
222 };
223 
224 struct configfs_subsystem {
225 	struct config_group	su_group;
226 	struct mutex		su_mutex;
227 };
228 
to_configfs_subsystem(struct config_group * group)229 static inline struct configfs_subsystem *to_configfs_subsystem(struct config_group *group)
230 {
231 	return group ?
232 		container_of(group, struct configfs_subsystem, su_group) :
233 		NULL;
234 }
235 
236 int configfs_register_subsystem(struct configfs_subsystem *subsys);
237 void configfs_unregister_subsystem(struct configfs_subsystem *subsys);
238 
239 int configfs_register_group(struct config_group *parent_group,
240 			    struct config_group *group);
241 void configfs_unregister_group(struct config_group *group);
242 
243 void configfs_remove_default_groups(struct config_group *group);
244 
245 struct config_group *
246 configfs_register_default_group(struct config_group *parent_group,
247 				const char *name,
248 				const struct config_item_type *item_type);
249 void configfs_unregister_default_group(struct config_group *group);
250 
251 /* These functions can sleep and can alloc with GFP_KERNEL */
252 /* WARNING: These cannot be called underneath configfs callbacks!! */
253 int configfs_depend_item(struct configfs_subsystem *subsys,
254 			 struct config_item *target);
255 void configfs_undepend_item(struct config_item *target);
256 
257 /*
258  * These functions can sleep and can alloc with GFP_KERNEL
259  * NOTE: These should be called only underneath configfs callbacks.
260  * NOTE: First parameter is a caller's subsystem, not target's.
261  * WARNING: These cannot be called on newly created item
262  *        (in make_group()/make_item() callback)
263  */
264 int configfs_depend_item_unlocked(struct configfs_subsystem *caller_subsys,
265 				  struct config_item *target);
266 
267 
configfs_undepend_item_unlocked(struct config_item * target)268 static inline void configfs_undepend_item_unlocked(struct config_item *target)
269 {
270 	configfs_undepend_item(target);
271 }
272 
273 #endif /* _CONFIGFS_H_ */
274