1/* -*- mode: c; c-basic-offset: 8; -*-
2 * vim: noexpandtab sw=8 ts=8 sts=0:
3 *
4 * configfs_macros.h - extends macros for configfs
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 * Added CONFIGFS_EATTR() macros from original configfs.h macros
31 * Copright (C) 2008-2009 Nicholas A. Bellinger <nab@linux-iscsi.org>
32 *
33 * Please read Documentation/filesystems/configfs/configfs.txt before using
34 * the configfs interface, ESPECIALLY the parts about reference counts and
35 * item destructors.
36 */
37
38#ifndef _CONFIGFS_MACROS_H_
39#define _CONFIGFS_MACROS_H_
40
41#include <linux/configfs.h>
42
43/*
44 * Users often need to create attribute structures for their configurable
45 * attributes, containing a configfs_attribute member and function pointers
46 * for the show() and store() operations on that attribute. If they don't
47 * need anything else on the extended attribute structure, they can use
48 * this macro to define it.  The argument _name isends up as
49 * 'struct _name_attribute, as well as names of to CONFIGFS_ATTR_OPS() below.
50 * The argument _item is the name of the structure containing the
51 * struct config_item or struct config_group structure members
52 */
53#define CONFIGFS_EATTR_STRUCT(_name, _item)				\
54struct _name##_attribute {						\
55	struct configfs_attribute attr;					\
56	ssize_t (*show)(struct _item *, char *);			\
57	ssize_t (*store)(struct _item *, const char *, size_t);		\
58}
59
60/*
61 * With the extended attribute structure, users can use this macro
62 * (similar to sysfs' __ATTR) to make defining attributes easier.
63 * An example:
64 * #define MYITEM_EATTR(_name, _mode, _show, _store)	\
65 * struct myitem_attribute childless_attr_##_name =	\
66 *         __CONFIGFS_EATTR(_name, _mode, _show, _store)
67 */
68#define __CONFIGFS_EATTR(_name, _mode, _show, _store)			\
69{									\
70	.attr	= {							\
71			.ca_name = __stringify(_name),			\
72			.ca_mode = _mode,				\
73			.ca_owner = THIS_MODULE,			\
74	},								\
75	.show	= _show,						\
76	.store	= _store,						\
77}
78/* Here is a readonly version, only requiring a show() operation */
79#define __CONFIGFS_EATTR_RO(_name, _show)				\
80{									\
81	.attr	= {							\
82			.ca_name = __stringify(_name),			\
83			.ca_mode = 0444,				\
84			.ca_owner = THIS_MODULE,			\
85	},								\
86	.show	= _show,						\
87}
88
89/*
90 * With these extended attributes, the simple show_attribute() and
91 * store_attribute() operations need to call the show() and store() of the
92 * attributes.  This is a common pattern, so we provide a macro to define
93 * them.  The argument _name is the name of the attribute defined by
94 * CONFIGFS_ATTR_STRUCT(). The argument _item is the name of the structure
95 * containing the struct config_item or struct config_group structure member.
96 * The argument _item_member is the actual name of the struct config_* struct
97 * in your _item structure.  Meaning  my_structure->some_config_group.
98 *		                      ^^_item^^^^^  ^^_item_member^^^
99 * This macro expects the attributes to be named "struct <name>_attribute".
100 */
101#define CONFIGFS_EATTR_OPS_TO_FUNC(_name, _item, _item_member)		\
102static struct _item *to_##_name(struct config_item *ci)			\
103{									\
104	return (ci) ? container_of(to_config_group(ci), struct _item,	\
105		_item_member) : NULL;					\
106}
107
108#define CONFIGFS_EATTR_OPS_SHOW(_name, _item)				\
109static ssize_t _name##_attr_show(struct config_item *item,		\
110				 struct configfs_attribute *attr,	\
111				 char *page)				\
112{									\
113	struct _item *_item = to_##_name(item);				\
114	struct _name##_attribute * _name##_attr =			\
115		container_of(attr, struct _name##_attribute, attr);	\
116	ssize_t ret = 0;						\
117									\
118	if (_name##_attr->show)						\
119		ret = _name##_attr->show(_item, page);			\
120	return ret;							\
121}
122
123#define CONFIGFS_EATTR_OPS_STORE(_name, _item)				\
124static ssize_t _name##_attr_store(struct config_item *item,		\
125				  struct configfs_attribute *attr,	\
126				  const char *page, size_t count)	\
127{									\
128	struct _item *_item = to_##_name(item);				\
129	struct _name##_attribute * _name##_attr =			\
130		container_of(attr, struct _name##_attribute, attr);	\
131	ssize_t ret = -EINVAL;						\
132									\
133	if (_name##_attr->store)					\
134		ret = _name##_attr->store(_item, page, count);		\
135	return ret;							\
136}
137
138#define CONFIGFS_EATTR_OPS(_name, _item, _item_member)			\
139	CONFIGFS_EATTR_OPS_TO_FUNC(_name, _item, _item_member);		\
140	CONFIGFS_EATTR_OPS_SHOW(_name, _item);				\
141	CONFIGFS_EATTR_OPS_STORE(_name, _item);
142
143#define CONFIGFS_EATTR_OPS_RO(_name, _item, _item_member)		\
144	CONFIGFS_EATTR_OPS_TO_FUNC(_name, _item, _item_member);		\
145	CONFIGFS_EATTR_OPS_SHOW(_name, _item);
146
147#endif /* _CONFIGFS_MACROS_H_ */
148