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
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
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
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
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
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 */
208 struct configfs_item_operations {
209 void (*release)(struct config_item *);
210 int (*allow_link)(struct config_item *src, struct config_item *target);
211 void (*drop_link)(struct config_item *src, struct config_item *target);
212 };
213
214 struct configfs_group_operations {
215 struct config_item *(*make_item)(struct config_group *group, const char *name);
216 struct config_group *(*make_group)(struct config_group *group, const char *name);
217 void (*disconnect_notify)(struct config_group *group, struct config_item *item);
218 void (*drop_item)(struct config_group *group, struct config_item *item);
219 bool (*is_visible)(struct config_item *item, struct configfs_attribute *attr, int n);
220 bool (*is_bin_visible)(struct config_item *item, struct configfs_bin_attribute *attr,
221 int n);
222 };
223
224 struct configfs_subsystem {
225 struct config_group su_group;
226 struct mutex su_mutex;
227 };
228
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
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
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