/* -*- mode: c; c-basic-offset: 8; -*-
   * vim: noexpandtab sw=8 ts=8 sts=0:
   *
   * configfs.h - definitions for the device driver filesystem
   *
   * 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.
   *
   * Please read Documentation/filesystems/configfs/configfs.txt before using
   * the configfs interface, ESPECIALLY the parts about reference counts and
   * item destructors.
   */
  
  #ifndef _CONFIGFS_H_
  #define _CONFIGFS_H_
  
  #include <linux/kernel.h>
  #include <linux/types.h>
  #include <linux/list.h>
  #include <linux/kref.h>
  #include <linux/mutex.h>
  #include <linux/err.h>
  
  #include <linux/atomic.h>
  
  #define CONFIGFS_ITEM_NAME_LEN	20
  
  struct module;
  
  struct configfs_item_operations;
  struct configfs_group_operations;
  struct configfs_attribute;
  struct configfs_subsystem;
  
  struct config_item {
  	char			*ci_name;
  	char			ci_namebuf[CONFIGFS_ITEM_NAME_LEN];
  	struct kref		ci_kref;
  	struct list_head	ci_entry;
  	struct config_item	*ci_parent;
  	struct config_group	*ci_group;
  	struct config_item_type	*ci_type;
  	struct dentry		*ci_dentry;
  };
  
  extern int config_item_set_name(struct config_item *, const char *, ...);
  
  static inline char *config_item_name(struct config_item * item)
  {
  	return item->ci_name;
  }
  
  extern void config_item_init(struct config_item *);
  extern void config_item_init_type_name(struct config_item *item,
  				       const char *name,
  				       struct config_item_type *type);
  
  extern struct config_item * config_item_get(struct config_item *);
  extern void config_item_put(struct config_item *);
  
  struct config_item_type {
  	struct module				*ct_owner;
  	struct configfs_item_operations		*ct_item_ops;
  	struct configfs_group_operations	*ct_group_ops;
  	struct configfs_attribute		**ct_attrs;
  };
  
  /**
   *	group - a group of config_items of a specific type, belonging
   *	to a specific subsystem.
   */
  struct config_group {
  	struct config_item		cg_item;
  	struct list_head		cg_children;
  	struct configfs_subsystem 	*cg_subsys;
  	struct config_group		**default_groups;
  };
  
  extern void config_group_init(struct config_group *group);
  extern void config_group_init_type_name(struct config_group *group,
  					const char *name,
  					struct config_item_type *type);
  
  static inline struct config_group *to_config_group(struct config_item *item)
  {
  	return item ? container_of(item,struct config_group,cg_item) : NULL;
  }
  
  static inline struct config_group *config_group_get(struct config_group *group)
  {
  	return group ? to_config_group(config_item_get(&group->cg_item)) : NULL;
  }
  
  static inline void config_group_put(struct config_group *group)
  {
  	config_item_put(&group->cg_item);
  }
  
  extern struct config_item *config_group_find_item(struct config_group *,
  						  const char *);
  
  
  struct configfs_attribute {
  	const char		*ca_name;
  	struct module 		*ca_owner;
  	umode_t			ca_mode;
  };
  
  /*
   * 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 _item is the name of the
   * config_item structure.
   */
  #define CONFIGFS_ATTR_STRUCT(_item)					\
  struct _item##_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_ATTR(_name, _mode, _show, _store)	\
   * struct myitem_attribute childless_attr_##_name =	\
   *         __CONFIGFS_ATTR(_name, _mode, _show, _store)
   */
  #define __CONFIGFS_ATTR(_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_ATTR_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 _item is the name of the config_item structure.
   * This macro expects the attributes to be named "struct <name>_attribute"
   * and the function to_<name>() to exist;
   */
  #define CONFIGFS_ATTR_OPS(_item)					\
  static ssize_t _item##_attr_show(struct config_item *item,		\
  				 struct configfs_attribute *attr,	\
  				 char *page)				\
  {									\
  	struct _item *_item = to_##_item(item);				\
  	struct _item##_attribute *_item##_attr =			\
  		container_of(attr, struct _item##_attribute, attr);	\
  	ssize_t ret = 0;						\
  									\
  	if (_item##_attr->show)						\
  		ret = _item##_attr->show(_item, page);			\
  	return ret;							\
  }									\
  static ssize_t _item##_attr_store(struct config_item *item,		\
  				  struct configfs_attribute *attr,	\
  				  const char *page, size_t count)	\
  {									\
  	struct _item *_item = to_##_item(item);				\
  	struct _item##_attribute *_item##_attr =			\
  		container_of(attr, struct _item##_attribute, attr);	\
  	ssize_t ret = -EINVAL;						\
  									\
  	if (_item##_attr->store)					\
  		ret = _item##_attr->store(_item, page, count);		\
  	return ret;							\
  }
  
  /*
   * If allow_link() exists, the item can symlink(2) out to other
   * items.  If the item is a group, it may support mkdir(2).
   * Groups supply one of make_group() and make_item().  If the
   * group supports make_group(), one can create group children.  If it
   * supports make_item(), one can create config_item children.  make_group()
   * and make_item() return ERR_PTR() on errors.  If it has
   * default_groups on group->default_groups, it has automatically created
   * group children.  default_groups may coexist alongsize make_group() or
   * make_item(), but if the group wishes to have only default_groups
   * children (disallowing mkdir(2)), it need not provide either function.
   * If the group has commit(), it supports pending and committed (active)
   * items.
   */
  struct configfs_item_operations {
  	void (*release)(struct config_item *);
  	ssize_t	(*show_attribute)(struct config_item *, struct configfs_attribute *,char *);
  	ssize_t	(*store_attribute)(struct config_item *,struct configfs_attribute *,const char *, size_t);
  	int (*allow_link)(struct config_item *src, struct config_item *target);
  	int (*drop_link)(struct config_item *src, struct config_item *target);
  };
  
  struct configfs_group_operations {
  	struct config_item *(*make_item)(struct config_group *group, const char *name);
  	struct config_group *(*make_group)(struct config_group *group, const char *name);
  	int (*commit_item)(struct config_item *item);
  	void (*disconnect_notify)(struct config_group *group, struct config_item *item);
  	void (*drop_item)(struct config_group *group, struct config_item *item);
  };
  
  struct configfs_subsystem {
  	struct config_group	su_group;
  	struct mutex		su_mutex;
  };
  
  static inline struct configfs_subsystem *to_configfs_subsystem(struct config_group *group)
  {
  	return group ?
  		container_of(group, struct configfs_subsystem, su_group) :
  		NULL;
  }
  
  int configfs_register_subsystem(struct configfs_subsystem *subsys);
  void configfs_unregister_subsystem(struct configfs_subsystem *subsys);
  
  /* These functions can sleep and can alloc with GFP_KERNEL */
  /* WARNING: These cannot be called underneath configfs callbacks!! */
  int configfs_depend_item(struct configfs_subsystem *subsys, struct config_item *target);
  void configfs_undepend_item(struct configfs_subsystem *subsys, struct config_item *target);
  
  #endif /* _CONFIGFS_H_ */