7fe74608b437faaad7e4f091469c8d0d8a9d0c2d
[linux-2.6.git] / include / target / configfs_macros.h
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.txt before using the
34  * 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)                             \
54 struct _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)          \
102 static 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)                           \
109 static 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)                          \
124 static 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_ */