/*
   * vim: noexpandtab ts=8 sts=0 sw=8:
   *

   * configfs_example_macros.c - This file is a demonstration module
   *      containing a number of configfs subsystems.  It uses the helper
   *      macros defined by configfs.h

   *
   * 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
   *
   * configfs Copyright (C) 2005 Oracle.  All rights reserved.
   */
  
  #include <linux/init.h>
  #include <linux/module.h>
  #include <linux/slab.h>
  
  #include <linux/configfs.h>
  
  
  
  /*
   * 01-childless
   *
   * This first example is a childless subsystem.  It cannot create
   * any config_items.  It just has attributes.
   *
   * Note that we are enclosing the configfs_subsystem inside a container.
   * This is not necessary if a subsystem has no attributes directly
   * on the subsystem.  See the next example, 02-simple-children, for
   * such a subsystem.
   */
  
  struct childless {
  	struct configfs_subsystem subsys;
  	int showme;
  	int storeme;
  };

  static inline struct childless *to_childless(struct config_item *item)
  {

  	return item ? container_of(to_configfs_subsystem(to_config_group(item)),
  			struct childless, subsys) : NULL;

  }

  static ssize_t childless_showme_show(struct config_item *item, char *page)

  {

  	struct childless *childless = to_childless(item);

  	ssize_t pos;
  
  	pos = sprintf(page, "%d
  ", childless->showme);
  	childless->showme++;
  
  	return pos;
  }

  static ssize_t childless_storeme_show(struct config_item *item, char *page)

  {

  	return sprintf(page, "%d
  ", to_childless(item)->storeme);

  }

  static ssize_t childless_storeme_store(struct config_item *item,
  		const char *page, size_t count)

  {

  	struct childless *childless = to_childless(item);

  	unsigned long tmp;
  	char *p = (char *) page;
  
  	tmp = simple_strtoul(p, &p, 10);
  	if (!p || (*p && (*p != '
  ')))
  		return -EINVAL;
  
  	if (tmp > INT_MAX)
  		return -ERANGE;
  
  	childless->storeme = tmp;
  
  	return count;
  }

  static ssize_t childless_description_show(struct config_item *item, char *page)

  {
  	return sprintf(page,
  "[01-childless]
  "
  "
  "
  "The childless subsystem is the simplest possible subsystem in
  "
  "configfs.  It does not support the creation of child config_items.
  "
  "It only has a few attributes.  In fact, it isn't much different
  "
  "than a directory in /proc.
  ");
  }

  CONFIGFS_ATTR_RO(childless_, showme);
  CONFIGFS_ATTR(childless_, storeme);
  CONFIGFS_ATTR_RO(childless_, description);

  
  static struct configfs_attribute *childless_attrs[] = {

  	&childless_attr_showme,
  	&childless_attr_storeme,
  	&childless_attr_description,

  	NULL,
  };

  static struct config_item_type childless_type = {

  	.ct_attrs	= childless_attrs,
  	.ct_owner	= THIS_MODULE,
  };
  
  static struct childless childless_subsys = {
  	.subsys = {
  		.su_group = {
  			.cg_item = {
  				.ci_namebuf = "01-childless",
  				.ci_type = &childless_type,
  			},
  		},
  	},
  };
  
  
  /* ----------------------------------------------------------------- */
  
  /*
   * 02-simple-children
   *
   * This example merely has a simple one-attribute child.  Note that
   * there is no extra attribute structure, as the child's attribute is
   * known from the get-go.  Also, there is no container for the
   * subsystem, as it has no attributes of its own.
   */
  
  struct simple_child {
  	struct config_item item;
  	int storeme;
  };
  
  static inline struct simple_child *to_simple_child(struct config_item *item)
  {
  	return item ? container_of(item, struct simple_child, item) : NULL;
  }

  static ssize_t simple_child_storeme_show(struct config_item *item, char *page)

  {

  	return sprintf(page, "%d
  ", to_simple_child(item)->storeme);

  }

  static ssize_t simple_child_storeme_store(struct config_item *item,
  		const char *page, size_t count)

  {
  	struct simple_child *simple_child = to_simple_child(item);
  	unsigned long tmp;
  	char *p = (char *) page;
  
  	tmp = simple_strtoul(p, &p, 10);
  	if (!p || (*p && (*p != '
  ')))
  		return -EINVAL;
  
  	if (tmp > INT_MAX)
  		return -ERANGE;
  
  	simple_child->storeme = tmp;
  
  	return count;
  }

  CONFIGFS_ATTR(simple_child_, storeme);
  
  static struct configfs_attribute *simple_child_attrs[] = {
  	&simple_child_attr_storeme,
  	NULL,
  };

  static void simple_child_release(struct config_item *item)
  {
  	kfree(to_simple_child(item));
  }
  
  static struct configfs_item_operations simple_child_item_ops = {
  	.release		= simple_child_release,

  };
  
  static struct config_item_type simple_child_type = {
  	.ct_item_ops	= &simple_child_item_ops,
  	.ct_attrs	= simple_child_attrs,
  	.ct_owner	= THIS_MODULE,
  };

  struct simple_children {
  	struct config_group group;
  };
  
  static inline struct simple_children *to_simple_children(struct config_item *item)
  {

  	return item ? container_of(to_config_group(item),
  			struct simple_children, group) : NULL;

  }

  static struct config_item *simple_children_make_item(struct config_group *group,
  		const char *name)

  {
  	struct simple_child *simple_child;

  	simple_child = kzalloc(sizeof(struct simple_child), GFP_KERNEL);

  	if (!simple_child)

  		return ERR_PTR(-ENOMEM);

  	config_item_init_type_name(&simple_child->item, name,
  				   &simple_child_type);
  
  	simple_child->storeme = 0;

  	return &simple_child->item;

  }

  static ssize_t simple_children_description_show(struct config_item *item,
  		char *page)

  {
  	return sprintf(page,
  "[02-simple-children]
  "
  "
  "
  "This subsystem allows the creation of child config_items.  These
  "
  "items have only one attribute that is readable and writeable.
  ");
  }

  CONFIGFS_ATTR_RO(simple_children_, description);
  
  static struct configfs_attribute *simple_children_attrs[] = {
  	&simple_children_attr_description,
  	NULL,
  };

  static void simple_children_release(struct config_item *item)
  {
  	kfree(to_simple_children(item));
  }

  static struct configfs_item_operations simple_children_item_ops = {

  	.release	= simple_children_release,

  };
  
  /*
   * Note that, since no extra work is required on ->drop_item(),
   * no ->drop_item() is provided.
   */
  static struct configfs_group_operations simple_children_group_ops = {
  	.make_item	= simple_children_make_item,
  };
  
  static struct config_item_type simple_children_type = {
  	.ct_item_ops	= &simple_children_item_ops,
  	.ct_group_ops	= &simple_children_group_ops,
  	.ct_attrs	= simple_children_attrs,

  	.ct_owner	= THIS_MODULE,

  };
  
  static struct configfs_subsystem simple_children_subsys = {
  	.su_group = {
  		.cg_item = {
  			.ci_namebuf = "02-simple-children",
  			.ci_type = &simple_children_type,
  		},
  	},
  };
  
  
  /* ----------------------------------------------------------------- */
  
  /*
   * 03-group-children
   *
   * This example reuses the simple_children group from above.  However,
   * the simple_children group is not the subsystem itself, it is a
   * child of the subsystem.  Creation of a group in the subsystem creates
   * a new simple_children group.  That group can then have simple_child
   * children of its own.
   */

  static struct config_group *group_children_make_group(
  		struct config_group *group, const char *name)

  {
  	struct simple_children *simple_children;

  	simple_children = kzalloc(sizeof(struct simple_children),

  				  GFP_KERNEL);
  	if (!simple_children)

  		return ERR_PTR(-ENOMEM);

  	config_group_init_type_name(&simple_children->group, name,
  				    &simple_children_type);

  	return &simple_children->group;

  }

  static ssize_t group_children_description_show(struct config_item *item,
  		char *page)

  {
  	return sprintf(page,
  "[03-group-children]
  "
  "
  "
  "This subsystem allows the creation of child config_groups.  These
  "
  "groups are like the subsystem simple-children.
  ");
  }

  CONFIGFS_ATTR_RO(group_children_, description);
  
  static struct configfs_attribute *group_children_attrs[] = {
  	&group_children_attr_description,
  	NULL,

  };
  
  /*
   * Note that, since no extra work is required on ->drop_item(),
   * no ->drop_item() is provided.
   */
  static struct configfs_group_operations group_children_group_ops = {
  	.make_group	= group_children_make_group,
  };
  
  static struct config_item_type group_children_type = {

  	.ct_group_ops	= &group_children_group_ops,
  	.ct_attrs	= group_children_attrs,

  	.ct_owner	= THIS_MODULE,

  };
  
  static struct configfs_subsystem group_children_subsys = {
  	.su_group = {
  		.cg_item = {
  			.ci_namebuf = "03-group-children",
  			.ci_type = &group_children_type,
  		},
  	},
  };
  
  /* ----------------------------------------------------------------- */
  
  /*
   * We're now done with our subsystem definitions.
   * For convenience in this module, here's a list of them all.  It
   * allows the init function to easily register them.  Most modules
   * will only have one subsystem, and will only call register_subsystem
   * on it directly.
   */
  static struct configfs_subsystem *example_subsys[] = {
  	&childless_subsys.subsys,
  	&simple_children_subsys,
  	&group_children_subsys,
  	NULL,
  };
  
  static int __init configfs_example_init(void)
  {
  	int ret;
  	int i;
  	struct configfs_subsystem *subsys;
  
  	for (i = 0; example_subsys[i]; i++) {
  		subsys = example_subsys[i];
  
  		config_group_init(&subsys->su_group);

  		mutex_init(&subsys->su_mutex);

  		ret = configfs_register_subsystem(subsys);
  		if (ret) {
  			printk(KERN_ERR "Error %d while registering subsystem %s
  ",
  			       ret,
  			       subsys->su_group.cg_item.ci_namebuf);
  			goto out_unregister;
  		}
  	}
  
  	return 0;
  
  out_unregister:

  	for (i--; i >= 0; i--)

  		configfs_unregister_subsystem(example_subsys[i]);

  
  	return ret;
  }
  
  static void __exit configfs_example_exit(void)
  {
  	int i;

  	for (i = 0; example_subsys[i]; i++)

  		configfs_unregister_subsystem(example_subsys[i]);

  }
  
  module_init(configfs_example_init);
  module_exit(configfs_example_exit);
  MODULE_LICENSE("GPL");