/* -*- mode: c; c-basic-offset: 8; -*-
   * vim: noexpandtab sw=8 ts=8 sts=0:
   *
   * configfs_macros.h - extends macros for configfs
   *
   * This program is free software; you can redistribute it and/or
   * modify it under the terms of the GNU General Public
   * License as published by the Free Software Foundation; either
   * version 2 of the License, or (at your option) any later version.
   *
   * This program is distributed in the hope that it will be useful,
   * but WITHOUT ANY WARRANTY; without even the implied warranty of
   * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
   * General Public License for more details.
   *
   * You should have received a copy of the GNU General Public
   * License along with this program; if not, write to the
   * Free Software Foundation, Inc., 59 Temple Place - Suite 330,
   * Boston, MA 021110-1307, USA.
   *
   * Based on sysfs:
   * 	sysfs is Copyright (C) 2001, 2002, 2003 Patrick Mochel
   *
   * Based on kobject.h:
   *      Copyright (c) 2002-2003	Patrick Mochel
   *      Copyright (c) 2002-2003	Open Source Development Labs
   *
   * configfs Copyright (C) 2005 Oracle.  All rights reserved.
   *
   * Added CONFIGFS_EATTR() macros from original configfs.h macros
   * Copright (C) 2008-2009 Nicholas A. Bellinger <nab@linux-iscsi.org>
   *
   * Please read Documentation/filesystems/configfs/configfs.txt before using
   * the configfs interface, ESPECIALLY the parts about reference counts and
   * item destructors.
   */
  
  #ifndef _CONFIGFS_MACROS_H_
  #define _CONFIGFS_MACROS_H_
  
  #include <linux/configfs.h>
  
  /*
   * Users often need to create attribute structures for their configurable
   * attributes, containing a configfs_attribute member and function pointers
   * for the show() and store() operations on that attribute. If they don't
   * need anything else on the extended attribute structure, they can use
   * this macro to define it.  The argument _name isends up as
   * 'struct _name_attribute, as well as names of to CONFIGFS_ATTR_OPS() below.
   * The argument _item is the name of the structure containing the
   * struct config_item or struct config_group structure members
   */
  #define CONFIGFS_EATTR_STRUCT(_name, _item)				\
  struct _name##_attribute {						\
  	struct configfs_attribute attr;					\
  	ssize_t (*show)(struct _item *, char *);			\
  	ssize_t (*store)(struct _item *, const char *, size_t);		\
  }
  
  /*
   * With the extended attribute structure, users can use this macro
   * (similar to sysfs' __ATTR) to make defining attributes easier.
   * An example:
   * #define MYITEM_EATTR(_name, _mode, _show, _store)	\
   * struct myitem_attribute childless_attr_##_name =	\
   *         __CONFIGFS_EATTR(_name, _mode, _show, _store)
   */
  #define __CONFIGFS_EATTR(_name, _mode, _show, _store)			\
  {									\
  	.attr	= {							\
  			.ca_name = __stringify(_name),			\
  			.ca_mode = _mode,				\
  			.ca_owner = THIS_MODULE,			\
  	},								\
  	.show	= _show,						\
  	.store	= _store,						\
  }
  /* Here is a readonly version, only requiring a show() operation */
  #define __CONFIGFS_EATTR_RO(_name, _show)				\
  {									\
  	.attr	= {							\
  			.ca_name = __stringify(_name),			\
  			.ca_mode = 0444,				\
  			.ca_owner = THIS_MODULE,			\
  	},								\
  	.show	= _show,						\
  }
  
  /*
   * With these extended attributes, the simple show_attribute() and
   * store_attribute() operations need to call the show() and store() of the
   * attributes.  This is a common pattern, so we provide a macro to define
   * them.  The argument _name is the name of the attribute defined by
   * CONFIGFS_ATTR_STRUCT(). The argument _item is the name of the structure
   * containing the struct config_item or struct config_group structure member.
   * The argument _item_member is the actual name of the struct config_* struct
   * in your _item structure.  Meaning  my_structure->some_config_group.
   *		                      ^^_item^^^^^  ^^_item_member^^^
   * This macro expects the attributes to be named "struct <name>_attribute".
   */
  #define CONFIGFS_EATTR_OPS_TO_FUNC(_name, _item, _item_member)		\
  static struct _item *to_##_name(struct config_item *ci)			\
  {									\
  	return (ci) ? container_of(to_config_group(ci), struct _item,	\
  		_item_member) : NULL;					\
  }
  
  #define CONFIGFS_EATTR_OPS_SHOW(_name, _item)				\
  static ssize_t _name##_attr_show(struct config_item *item,		\
  				 struct configfs_attribute *attr,	\
  				 char *page)				\
  {									\
  	struct _item *_item = to_##_name(item);				\
  	struct _name##_attribute * _name##_attr =			\
  		container_of(attr, struct _name##_attribute, attr);	\
  	ssize_t ret = 0;						\
  									\
  	if (_name##_attr->show)						\
  		ret = _name##_attr->show(_item, page);			\
  	return ret;							\
  }
  
  #define CONFIGFS_EATTR_OPS_STORE(_name, _item)				\
  static ssize_t _name##_attr_store(struct config_item *item,		\
  				  struct configfs_attribute *attr,	\
  				  const char *page, size_t count)	\
  {									\
  	struct _item *_item = to_##_name(item);				\
  	struct _name##_attribute * _name##_attr =			\
  		container_of(attr, struct _name##_attribute, attr);	\
  	ssize_t ret = -EINVAL;						\
  									\
  	if (_name##_attr->store)					\
  		ret = _name##_attr->store(_item, page, count);		\
  	return ret;							\
  }
  
  #define CONFIGFS_EATTR_OPS(_name, _item, _item_member)			\
  	CONFIGFS_EATTR_OPS_TO_FUNC(_name, _item, _item_member);		\
  	CONFIGFS_EATTR_OPS_SHOW(_name, _item);				\
  	CONFIGFS_EATTR_OPS_STORE(_name, _item);
  
  #define CONFIGFS_EATTR_OPS_RO(_name, _item, _item_member)		\
  	CONFIGFS_EATTR_OPS_TO_FUNC(_name, _item, _item_member);		\
  	CONFIGFS_EATTR_OPS_SHOW(_name, _item);
  
  #endif /* _CONFIGFS_MACROS_H_ */