1/* -*- mode: c; c-basic-offset: 8; -*-
2 * vim: noexpandtab sw=8 ts=8 sts=0:
3 *
4 * configfs.h - definitions for the device driver filesystem
5 *
6 * This program is free software; you can redistribute it and/or
7 * modify it under the terms of the GNU General Public
8 * License as published by the Free Software Foundation; either
9 * version 2 of the License, or (at your option) any later version.
10 *
11 * This program is distributed in the hope that it will be useful,
12 * but WITHOUT ANY WARRANTY; without even the implied warranty of
13 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
14 * General Public License for more details.
15 *
16 * You should have received a copy of the GNU General Public
17 * License along with this program; if not, write to the
18 * Free Software Foundation, Inc., 59 Temple Place - Suite 330,
19 * Boston, MA 021110-1307, USA.
20 *
21 * Based on sysfs:
22 * 	sysfs is Copyright (C) 2001, 2002, 2003 Patrick Mochel
23 *
24 * Based on kobject.h:
25 *      Copyright (c) 2002-2003	Patrick Mochel
26 *      Copyright (c) 2002-2003	Open Source Development Labs
27 *
28 * configfs Copyright (C) 2005 Oracle.  All rights reserved.
29 *
30 * Please read Documentation/filesystems/configfs/configfs.txt before using
31 * the configfs interface, ESPECIALLY the parts about reference counts and
32 * item destructors.
33 */
34
35#ifndef _CONFIGFS_H_
36#define _CONFIGFS_H_
37
38#include <linux/kernel.h>
39#include <linux/types.h>
40#include <linux/list.h>
41#include <linux/kref.h>
42#include <linux/mutex.h>
43#include <linux/err.h>
44
45#include <linux/atomic.h>
46
47#define CONFIGFS_ITEM_NAME_LEN	20
48
49struct module;
50
51struct configfs_item_operations;
52struct configfs_group_operations;
53struct configfs_attribute;
54struct configfs_subsystem;
55
56struct config_item {
57	char			*ci_name;
58	char			ci_namebuf[CONFIGFS_ITEM_NAME_LEN];
59	struct kref		ci_kref;
60	struct list_head	ci_entry;
61	struct config_item	*ci_parent;
62	struct config_group	*ci_group;
63	struct config_item_type	*ci_type;
64	struct dentry		*ci_dentry;
65};
66
67extern int config_item_set_name(struct config_item *, const char *, ...);
68
69static inline char *config_item_name(struct config_item * item)
70{
71	return item->ci_name;
72}
73
74extern void config_item_init(struct config_item *);
75extern void config_item_init_type_name(struct config_item *item,
76				       const char *name,
77				       struct config_item_type *type);
78
79extern struct config_item * config_item_get(struct config_item *);
80extern void config_item_put(struct config_item *);
81
82struct config_item_type {
83	struct module				*ct_owner;
84	struct configfs_item_operations		*ct_item_ops;
85	struct configfs_group_operations	*ct_group_ops;
86	struct configfs_attribute		**ct_attrs;
87};
88
89/**
90 *	group - a group of config_items of a specific type, belonging
91 *	to a specific subsystem.
92 */
93struct config_group {
94	struct config_item		cg_item;
95	struct list_head		cg_children;
96	struct configfs_subsystem 	*cg_subsys;
97	struct config_group		**default_groups;
98};
99
100extern void config_group_init(struct config_group *group);
101extern void config_group_init_type_name(struct config_group *group,
102					const char *name,
103					struct config_item_type *type);
104
105static inline struct config_group *to_config_group(struct config_item *item)
106{
107	return item ? container_of(item,struct config_group,cg_item) : NULL;
108}
109
110static inline struct config_group *config_group_get(struct config_group *group)
111{
112	return group ? to_config_group(config_item_get(&group->cg_item)) : NULL;
113}
114
115static inline void config_group_put(struct config_group *group)
116{
117	config_item_put(&group->cg_item);
118}
119
120extern struct config_item *config_group_find_item(struct config_group *,
121						  const char *);
122
123
124struct configfs_attribute {
125	const char		*ca_name;
126	struct module 		*ca_owner;
127	umode_t			ca_mode;
128};
129
130/*
131 * Users often need to create attribute structures for their configurable
132 * attributes, containing a configfs_attribute member and function pointers
133 * for the show() and store() operations on that attribute. If they don't
134 * need anything else on the extended attribute structure, they can use
135 * this macro to define it  The argument _item is the name of the
136 * config_item structure.
137 */
138#define CONFIGFS_ATTR_STRUCT(_item)					\
139struct _item##_attribute {						\
140	struct configfs_attribute attr;					\
141	ssize_t (*show)(struct _item *, char *);			\
142	ssize_t (*store)(struct _item *, const char *, size_t);		\
143}
144
145/*
146 * With the extended attribute structure, users can use this macro
147 * (similar to sysfs' __ATTR) to make defining attributes easier.
148 * An example:
149 * #define MYITEM_ATTR(_name, _mode, _show, _store)	\
150 * struct myitem_attribute childless_attr_##_name =	\
151 *         __CONFIGFS_ATTR(_name, _mode, _show, _store)
152 */
153#define __CONFIGFS_ATTR(_name, _mode, _show, _store)			\
154{									\
155	.attr	= {							\
156			.ca_name = __stringify(_name),			\
157			.ca_mode = _mode,				\
158			.ca_owner = THIS_MODULE,			\
159	},								\
160	.show	= _show,						\
161	.store	= _store,						\
162}
163/* Here is a readonly version, only requiring a show() operation */
164#define __CONFIGFS_ATTR_RO(_name, _show)				\
165{									\
166	.attr	= {							\
167			.ca_name = __stringify(_name),			\
168			.ca_mode = 0444,				\
169			.ca_owner = THIS_MODULE,			\
170	},								\
171	.show	= _show,						\
172}
173
174/*
175 * With these extended attributes, the simple show_attribute() and
176 * store_attribute() operations need to call the show() and store() of the
177 * attributes.  This is a common pattern, so we provide a macro to define
178 * them.  The argument _item is the name of the config_item structure.
179 * This macro expects the attributes to be named "struct <name>_attribute"
180 * and the function to_<name>() to exist;
181 */
182#define CONFIGFS_ATTR_OPS(_item)					\
183static ssize_t _item##_attr_show(struct config_item *item,		\
184				 struct configfs_attribute *attr,	\
185				 char *page)				\
186{									\
187	struct _item *_item = to_##_item(item);				\
188	struct _item##_attribute *_item##_attr =			\
189		container_of(attr, struct _item##_attribute, attr);	\
190	ssize_t ret = 0;						\
191									\
192	if (_item##_attr->show)						\
193		ret = _item##_attr->show(_item, page);			\
194	return ret;							\
195}									\
196static ssize_t _item##_attr_store(struct config_item *item,		\
197				  struct configfs_attribute *attr,	\
198				  const char *page, size_t count)	\
199{									\
200	struct _item *_item = to_##_item(item);				\
201	struct _item##_attribute *_item##_attr =			\
202		container_of(attr, struct _item##_attribute, attr);	\
203	ssize_t ret = -EINVAL;						\
204									\
205	if (_item##_attr->store)					\
206		ret = _item##_attr->store(_item, page, count);		\
207	return ret;							\
208}
209
210/*
211 * If allow_link() exists, the item can symlink(2) out to other
212 * items.  If the item is a group, it may support mkdir(2).
213 * Groups supply one of make_group() and make_item().  If the
214 * group supports make_group(), one can create group children.  If it
215 * supports make_item(), one can create config_item children.  make_group()
216 * and make_item() return ERR_PTR() on errors.  If it has
217 * default_groups on group->default_groups, it has automatically created
218 * group children.  default_groups may coexist alongsize make_group() or
219 * make_item(), but if the group wishes to have only default_groups
220 * children (disallowing mkdir(2)), it need not provide either function.
221 * If the group has commit(), it supports pending and committed (active)
222 * items.
223 */
224struct configfs_item_operations {
225	void (*release)(struct config_item *);
226	ssize_t	(*show_attribute)(struct config_item *, struct configfs_attribute *,char *);
227	ssize_t	(*store_attribute)(struct config_item *,struct configfs_attribute *,const char *, size_t);
228	int (*allow_link)(struct config_item *src, struct config_item *target);
229	int (*drop_link)(struct config_item *src, struct config_item *target);
230};
231
232struct configfs_group_operations {
233	struct config_item *(*make_item)(struct config_group *group, const char *name);
234	struct config_group *(*make_group)(struct config_group *group, const char *name);
235	int (*commit_item)(struct config_item *item);
236	void (*disconnect_notify)(struct config_group *group, struct config_item *item);
237	void (*drop_item)(struct config_group *group, struct config_item *item);
238};
239
240struct configfs_subsystem {
241	struct config_group	su_group;
242	struct mutex		su_mutex;
243};
244
245static inline struct configfs_subsystem *to_configfs_subsystem(struct config_group *group)
246{
247	return group ?
248		container_of(group, struct configfs_subsystem, su_group) :
249		NULL;
250}
251
252int configfs_register_subsystem(struct configfs_subsystem *subsys);
253void configfs_unregister_subsystem(struct configfs_subsystem *subsys);
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, struct config_item *target);
258void configfs_undepend_item(struct configfs_subsystem *subsys, struct config_item *target);
259
260#endif /* _CONFIGFS_H_ */
261