1 /* SPDX-License-Identifier: GPL-2.0-or-later */
2 /* -*- mode: c; c-basic-offset: 8; -*-
3 * vim: noexpandtab sw=8 ts=8 sts=0:
4 *
5 * configfs.h - definitions for the device driver filesystem
6 *
7 * Based on sysfs:
8 * sysfs is Copyright (C) 2001, 2002, 2003 Patrick Mochel
9 *
10 * Based on kobject.h:
11 * Copyright (c) 2002-2003 Patrick Mochel
12 * Copyright (c) 2002-2003 Open Source Development Labs
13 *
14 * configfs Copyright (C) 2005 Oracle. All rights reserved.
15 *
16 * Please read Documentation/filesystems/configfs.rst before using
17 * the configfs interface, ESPECIALLY the parts about reference counts and
18 * item destructors.
19 */
20
21 #ifndef _CONFIGFS_H_
22 #define _CONFIGFS_H_
23
24 #include <linux/stat.h> /* S_IRUGO */
25 #include <linux/types.h> /* ssize_t */
26 #include <linux/list.h> /* struct list_head */
27 #include <linux/kref.h> /* struct kref */
28 #include <linux/mutex.h> /* struct mutex */
29
30 #define CONFIGFS_ITEM_NAME_LEN 20
31
32 struct module;
33
34 struct configfs_item_operations;
35 struct configfs_group_operations;
36 struct configfs_attribute;
37 struct configfs_bin_attribute;
38 struct configfs_subsystem;
39
40 struct config_item {
41 char *ci_name;
42 char ci_namebuf[CONFIGFS_ITEM_NAME_LEN];
43 struct kref ci_kref;
44 struct list_head ci_entry;
45 struct config_item *ci_parent;
46 struct config_group *ci_group;
47 const struct config_item_type *ci_type;
48 struct dentry *ci_dentry;
49 };
50
51 extern __printf(2, 3)
52 int config_item_set_name(struct config_item *, const char *, ...);
53
config_item_name(struct config_item * item)54 static inline char *config_item_name(struct config_item * item)
55 {
56 return item->ci_name;
57 }
58
59 extern void config_item_init_type_name(struct config_item *item,
60 const char *name,
61 const struct config_item_type *type);
62
63 extern struct config_item *config_item_get(struct config_item *);
64 extern struct config_item *config_item_get_unless_zero(struct config_item *);
65 extern void config_item_put(struct config_item *);
66
67 struct config_item_type {
68 struct module *ct_owner;
69 struct configfs_item_operations *ct_item_ops;
70 struct configfs_group_operations *ct_group_ops;
71 struct configfs_attribute **ct_attrs;
72 struct configfs_bin_attribute **ct_bin_attrs;
73 };
74
75 /**
76 * group - a group of config_items of a specific type, belonging
77 * to a specific subsystem.
78 */
79 struct config_group {
80 struct config_item cg_item;
81 struct list_head cg_children;
82 struct configfs_subsystem *cg_subsys;
83 struct list_head default_groups;
84 struct list_head group_entry;
85 };
86
87 extern void config_group_init(struct config_group *group);
88 extern void config_group_init_type_name(struct config_group *group,
89 const char *name,
90 const struct config_item_type *type);
91
to_config_group(struct config_item * item)92 static inline struct config_group *to_config_group(struct config_item *item)
93 {
94 return item ? container_of(item,struct config_group,cg_item) : NULL;
95 }
96
config_group_get(struct config_group * group)97 static inline struct config_group *config_group_get(struct config_group *group)
98 {
99 return group ? to_config_group(config_item_get(&group->cg_item)) : NULL;
100 }
101
config_group_put(struct config_group * group)102 static inline void config_group_put(struct config_group *group)
103 {
104 config_item_put(&group->cg_item);
105 }
106
107 extern struct config_item *config_group_find_item(struct config_group *,
108 const char *);
109
110
configfs_add_default_group(struct config_group * new_group,struct config_group * group)111 static inline void configfs_add_default_group(struct config_group *new_group,
112 struct config_group *group)
113 {
114 list_add_tail(&new_group->group_entry, &group->default_groups);
115 }
116
117 struct configfs_attribute {
118 const char *ca_name;
119 struct module *ca_owner;
120 umode_t ca_mode;
121 ssize_t (*show)(struct config_item *, char *);
122 ssize_t (*store)(struct config_item *, const char *, size_t);
123 };
124
125 #define CONFIGFS_ATTR(_pfx, _name) \
126 static struct configfs_attribute _pfx##attr_##_name = { \
127 .ca_name = __stringify(_name), \
128 .ca_mode = S_IRUGO | S_IWUSR, \
129 .ca_owner = THIS_MODULE, \
130 .show = _pfx##_name##_show, \
131 .store = _pfx##_name##_store, \
132 }
133
134 #define CONFIGFS_ATTR_RO(_pfx, _name) \
135 static struct configfs_attribute _pfx##attr_##_name = { \
136 .ca_name = __stringify(_name), \
137 .ca_mode = S_IRUGO, \
138 .ca_owner = THIS_MODULE, \
139 .show = _pfx##_name##_show, \
140 }
141
142 #define CONFIGFS_ATTR_WO(_pfx, _name) \
143 static struct configfs_attribute _pfx##attr_##_name = { \
144 .ca_name = __stringify(_name), \
145 .ca_mode = S_IWUSR, \
146 .ca_owner = THIS_MODULE, \
147 .store = _pfx##_name##_store, \
148 }
149
150 struct file;
151 struct vm_area_struct;
152
153 struct configfs_bin_attribute {
154 struct configfs_attribute cb_attr; /* std. attribute */
155 void *cb_private; /* for user */
156 size_t cb_max_size; /* max core size */
157 ssize_t (*read)(struct config_item *, void *, size_t);
158 ssize_t (*write)(struct config_item *, const void *, size_t);
159 };
160
161 #define CONFIGFS_BIN_ATTR(_pfx, _name, _priv, _maxsz) \
162 static struct configfs_bin_attribute _pfx##attr_##_name = { \
163 .cb_attr = { \
164 .ca_name = __stringify(_name), \
165 .ca_mode = S_IRUGO | S_IWUSR, \
166 .ca_owner = THIS_MODULE, \
167 }, \
168 .cb_private = _priv, \
169 .cb_max_size = _maxsz, \
170 .read = _pfx##_name##_read, \
171 .write = _pfx##_name##_write, \
172 }
173
174 #define CONFIGFS_BIN_ATTR_RO(_pfx, _name, _priv, _maxsz) \
175 static struct configfs_bin_attribute _pfx##attr_##_name = { \
176 .cb_attr = { \
177 .ca_name = __stringify(_name), \
178 .ca_mode = S_IRUGO, \
179 .ca_owner = THIS_MODULE, \
180 }, \
181 .cb_private = _priv, \
182 .cb_max_size = _maxsz, \
183 .read = _pfx##_name##_read, \
184 }
185
186 #define CONFIGFS_BIN_ATTR_WO(_pfx, _name, _priv, _maxsz) \
187 static struct configfs_bin_attribute _pfx##attr_##_name = { \
188 .cb_attr = { \
189 .ca_name = __stringify(_name), \
190 .ca_mode = S_IWUSR, \
191 .ca_owner = THIS_MODULE, \
192 }, \
193 .cb_private = _priv, \
194 .cb_max_size = _maxsz, \
195 .write = _pfx##_name##_write, \
196 }
197
198 /*
199 * If allow_link() exists, the item can symlink(2) out to other
200 * items. If the item is a group, it may support mkdir(2).
201 * Groups supply one of make_group() and make_item(). If the
202 * group supports make_group(), one can create group children. If it
203 * supports make_item(), one can create config_item children. make_group()
204 * and make_item() return ERR_PTR() on errors. If it has
205 * default_groups on group->default_groups, it has automatically created
206 * group children. default_groups may coexist alongsize make_group() or
207 * make_item(), but if the group wishes to have only default_groups
208 * children (disallowing mkdir(2)), it need not provide either function.
209 * If the group has commit(), it supports pending and committed (active)
210 * items.
211 */
212 struct configfs_item_operations {
213 void (*release)(struct config_item *);
214 int (*allow_link)(struct config_item *src, struct config_item *target);
215 void (*drop_link)(struct config_item *src, struct config_item *target);
216 };
217
218 struct configfs_group_operations {
219 struct config_item *(*make_item)(struct config_group *group, const char *name);
220 struct config_group *(*make_group)(struct config_group *group, const char *name);
221 int (*commit_item)(struct config_item *item);
222 void (*disconnect_notify)(struct config_group *group, struct config_item *item);
223 void (*drop_item)(struct config_group *group, struct config_item *item);
224 };
225
226 struct configfs_subsystem {
227 struct config_group su_group;
228 struct mutex su_mutex;
229 };
230
to_configfs_subsystem(struct config_group * group)231 static inline struct configfs_subsystem *to_configfs_subsystem(struct config_group *group)
232 {
233 return group ?
234 container_of(group, struct configfs_subsystem, su_group) :
235 NULL;
236 }
237
238 int configfs_register_subsystem(struct configfs_subsystem *subsys);
239 void configfs_unregister_subsystem(struct configfs_subsystem *subsys);
240
241 int configfs_register_group(struct config_group *parent_group,
242 struct config_group *group);
243 void configfs_unregister_group(struct config_group *group);
244
245 void configfs_remove_default_groups(struct config_group *group);
246
247 struct config_group *
248 configfs_register_default_group(struct config_group *parent_group,
249 const char *name,
250 const struct config_item_type *item_type);
251 void configfs_unregister_default_group(struct config_group *group);
252
253 /* These functions can sleep and can alloc with GFP_KERNEL */
254 /* WARNING: These cannot be called underneath configfs callbacks!! */
255 int configfs_depend_item(struct configfs_subsystem *subsys,
256 struct config_item *target);
257 void configfs_undepend_item(struct config_item *target);
258
259 /*
260 * These functions can sleep and can alloc with GFP_KERNEL
261 * NOTE: These should be called only underneath configfs callbacks.
262 * NOTE: First parameter is a caller's subsystem, not target's.
263 * WARNING: These cannot be called on newly created item
264 * (in make_group()/make_item() callback)
265 */
266 int configfs_depend_item_unlocked(struct configfs_subsystem *caller_subsys,
267 struct config_item *target);
268
269
configfs_undepend_item_unlocked(struct config_item * target)270 static inline void configfs_undepend_item_unlocked(struct config_item *target)
271 {
272 configfs_undepend_item(target);
273 }
274
275 #endif /* _CONFIGFS_H_ */
276