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/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)                             \
  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_ */