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(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_group->group_entry, &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(_pfx, _name)			\
124static 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)			\
133static 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)			\
141static 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
148struct file;
149struct vm_area_struct;
150
151struct 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)		\
160static 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)	\
173static 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)	\
185static 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 */
208struct 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
214struct 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};
220
221struct configfs_subsystem {
222	struct config_group	su_group;
223	struct mutex		su_mutex;
224};
225
226static inline struct configfs_subsystem *to_configfs_subsystem(struct config_group *group)
227{
228	return group ?
229		container_of(group, struct configfs_subsystem, su_group) :
230		NULL;
231}
232
233int configfs_register_subsystem(struct configfs_subsystem *subsys);
234void configfs_unregister_subsystem(struct configfs_subsystem *subsys);
235
236int configfs_register_group(struct config_group *parent_group,
237			    struct config_group *group);
238void configfs_unregister_group(struct config_group *group);
239
240void configfs_remove_default_groups(struct config_group *group);
241
242struct config_group *
243configfs_register_default_group(struct config_group *parent_group,
244				const char *name,
245				const struct config_item_type *item_type);
246void configfs_unregister_default_group(struct config_group *group);
247
248/* These functions can sleep and can alloc with GFP_KERNEL */
249/* WARNING: These cannot be called underneath configfs callbacks!! */
250int configfs_depend_item(struct configfs_subsystem *subsys,
251			 struct config_item *target);
252void configfs_undepend_item(struct config_item *target);
253
254/*
255 * These functions can sleep and can alloc with GFP_KERNEL
256 * NOTE: These should be called only underneath configfs callbacks.
257 * NOTE: First parameter is a caller's subsystem, not target's.
258 * WARNING: These cannot be called on newly created item
259 *        (in make_group()/make_item() callback)
260 */
261int configfs_depend_item_unlocked(struct configfs_subsystem *caller_subsys,
262				  struct config_item *target);
263
264
265static inline void configfs_undepend_item_unlocked(struct config_item *target)
266{
267	configfs_undepend_item(target);
268}
269
270#endif /* _CONFIGFS_H_ */
271