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
30struct module;
31
32struct configfs_item_operations;
33struct configfs_group_operations;
34struct configfs_attribute;
35struct configfs_bin_attribute;
36struct configfs_subsystem;
37
38struct 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
49extern __printf(2, 3)
50int config_item_set_name(struct config_item *, const char *, ...);
51
52static inline char *config_item_name(struct config_item * item)
53{
54 return item->ci_name;
55}
56
57extern void config_item_init_type_name(struct config_item *item,
58 const char *name,
59 const struct config_item_type *type);
60
61extern struct config_item *config_item_get(struct config_item *);
62extern struct config_item *config_item_get_unless_zero(struct config_item *);
63extern void config_item_put(struct config_item *);
64
65struct 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 */
77struct 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
85extern void config_group_init(struct config_group *group);
86extern void config_group_init_type_name(struct config_group *group,
87 const char *name,
88 const struct config_item_type *type);
89
90static 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
95static inline struct config_group *config_group_get(struct config_group *group)
96{
97 return group ? to_config_group(item: config_item_get(&group->cg_item)) : NULL;
98}
99
100static inline void config_group_put(struct config_group *group)
101{
102 config_item_put(&group->cg_item);
103}
104
105extern struct config_item *config_group_find_item(struct config_group *,
106 const char *);
107
108
109static inline void configfs_add_default_group(struct config_group *new_group,
110 struct config_group *group)
111{
112 list_add_tail(new: &new_group->group_entry, head: &group->default_groups);
113}
114
115struct 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_PERM(_pfx, _name, _perm) \
124static struct configfs_attribute _pfx##attr_##_name = { \
125 .ca_name = __stringify(_name), \
126 .ca_mode = _perm, \
127 .ca_owner = THIS_MODULE, \
128 .show = _pfx##_name##_show, \
129 .store = _pfx##_name##_store, \
130}
131
132#define CONFIGFS_ATTR(_pfx, _name) CONFIGFS_ATTR_PERM( \
133 _pfx, _name, S_IRUGO | S_IWUSR \
134)
135
136#define CONFIGFS_ATTR_RO(_pfx, _name) \
137static struct configfs_attribute _pfx##attr_##_name = { \
138 .ca_name = __stringify(_name), \
139 .ca_mode = S_IRUGO, \
140 .ca_owner = THIS_MODULE, \
141 .show = _pfx##_name##_show, \
142}
143
144#define CONFIGFS_ATTR_WO(_pfx, _name) \
145static struct configfs_attribute _pfx##attr_##_name = { \
146 .ca_name = __stringify(_name), \
147 .ca_mode = S_IWUSR, \
148 .ca_owner = THIS_MODULE, \
149 .store = _pfx##_name##_store, \
150}
151
152struct file;
153struct vm_area_struct;
154
155struct configfs_bin_attribute {
156 struct configfs_attribute cb_attr; /* std. attribute */
157 void *cb_private; /* for user */
158 size_t cb_max_size; /* max core size */
159 ssize_t (*read)(struct config_item *, void *, size_t);
160 ssize_t (*write)(struct config_item *, const void *, size_t);
161};
162
163#define CONFIGFS_BIN_ATTR(_pfx, _name, _priv, _maxsz) \
164static struct configfs_bin_attribute _pfx##attr_##_name = { \
165 .cb_attr = { \
166 .ca_name = __stringify(_name), \
167 .ca_mode = S_IRUGO | S_IWUSR, \
168 .ca_owner = THIS_MODULE, \
169 }, \
170 .cb_private = _priv, \
171 .cb_max_size = _maxsz, \
172 .read = _pfx##_name##_read, \
173 .write = _pfx##_name##_write, \
174}
175
176#define CONFIGFS_BIN_ATTR_RO(_pfx, _name, _priv, _maxsz) \
177static struct configfs_bin_attribute _pfx##attr_##_name = { \
178 .cb_attr = { \
179 .ca_name = __stringify(_name), \
180 .ca_mode = S_IRUGO, \
181 .ca_owner = THIS_MODULE, \
182 }, \
183 .cb_private = _priv, \
184 .cb_max_size = _maxsz, \
185 .read = _pfx##_name##_read, \
186}
187
188#define CONFIGFS_BIN_ATTR_WO(_pfx, _name, _priv, _maxsz) \
189static struct configfs_bin_attribute _pfx##attr_##_name = { \
190 .cb_attr = { \
191 .ca_name = __stringify(_name), \
192 .ca_mode = S_IWUSR, \
193 .ca_owner = THIS_MODULE, \
194 }, \
195 .cb_private = _priv, \
196 .cb_max_size = _maxsz, \
197 .write = _pfx##_name##_write, \
198}
199
200/*
201 * If allow_link() exists, the item can symlink(2) out to other
202 * items. If the item is a group, it may support mkdir(2).
203 * Groups supply one of make_group() and make_item(). If the
204 * group supports make_group(), one can create group children. If it
205 * supports make_item(), one can create config_item children. make_group()
206 * and make_item() return ERR_PTR() on errors. If it has
207 * default_groups on group->default_groups, it has automatically created
208 * group children. default_groups may coexist alongsize make_group() or
209 * make_item(), but if the group wishes to have only default_groups
210 * children (disallowing mkdir(2)), it need not provide either function.
211 */
212struct 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
218struct 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 void (*disconnect_notify)(struct config_group *group, struct config_item *item);
222 void (*drop_item)(struct config_group *group, struct config_item *item);
223 bool (*is_visible)(struct config_item *item, struct configfs_attribute *attr, int n);
224 bool (*is_bin_visible)(struct config_item *item, struct configfs_bin_attribute *attr,
225 int n);
226};
227
228struct configfs_subsystem {
229 struct config_group su_group;
230 struct mutex su_mutex;
231};
232
233static inline struct configfs_subsystem *to_configfs_subsystem(struct config_group *group)
234{
235 return group ?
236 container_of(group, struct configfs_subsystem, su_group) :
237 NULL;
238}
239
240int configfs_register_subsystem(struct configfs_subsystem *subsys);
241void configfs_unregister_subsystem(struct configfs_subsystem *subsys);
242
243int configfs_register_group(struct config_group *parent_group,
244 struct config_group *group);
245void configfs_unregister_group(struct config_group *group);
246
247void configfs_remove_default_groups(struct config_group *group);
248
249struct config_group *
250configfs_register_default_group(struct config_group *parent_group,
251 const char *name,
252 const struct config_item_type *item_type);
253void configfs_unregister_default_group(struct config_group *group);
254
255/* These functions can sleep and can alloc with GFP_KERNEL */
256/* WARNING: These cannot be called underneath configfs callbacks!! */
257int configfs_depend_item(struct configfs_subsystem *subsys,
258 struct config_item *target);
259void configfs_undepend_item(struct config_item *target);
260
261/*
262 * These functions can sleep and can alloc with GFP_KERNEL
263 * NOTE: These should be called only underneath configfs callbacks.
264 * NOTE: First parameter is a caller's subsystem, not target's.
265 * WARNING: These cannot be called on newly created item
266 * (in make_group()/make_item() callback)
267 */
268int configfs_depend_item_unlocked(struct configfs_subsystem *caller_subsys,
269 struct config_item *target);
270
271
272static inline void configfs_undepend_item_unlocked(struct config_item *target)
273{
274 configfs_undepend_item(target);
275}
276
277#endif /* _CONFIGFS_H_ */
278