/*
   * Componentized device handling.
   *
   * This program is free software; you can redistribute it and/or modify
   * it under the terms of the GNU General Public License version 2 as
   * published by the Free Software Foundation.
   *
   * This is work in progress.  We gather up the component devices into a list,
   * and bind them when instructed.  At the moment, we're specific to the DRM
   * subsystem, and only handles one master device, but this doesn't have to be
   * the case.
   */
  #include <linux/component.h>
  #include <linux/device.h>
  #include <linux/kref.h>
  #include <linux/list.h>
  #include <linux/module.h>
  #include <linux/mutex.h>
  #include <linux/slab.h>

  struct component;

  struct component_match_array {
  	void *data;
  	int (*compare)(struct device *, void *);
  	void (*release)(struct device *, void *);
  	struct component *component;
  	bool duplicate;
  };

  struct component_match {
  	size_t alloc;
  	size_t num;

  	struct component_match_array *compare;

  };

  struct master {
  	struct list_head node;

  	bool bound;
  
  	const struct component_master_ops *ops;
  	struct device *dev;

  	struct component_match *match;

  };
  
  struct component {
  	struct list_head node;

  	struct master *master;
  	bool bound;
  
  	const struct component_ops *ops;
  	struct device *dev;
  };
  
  static DEFINE_MUTEX(component_mutex);
  static LIST_HEAD(component_list);
  static LIST_HEAD(masters);
  
  static struct master *__master_find(struct device *dev,
  	const struct component_master_ops *ops)
  {
  	struct master *m;
  
  	list_for_each_entry(m, &masters, node)
  		if (m->dev == dev && (!ops || m->ops == ops))
  			return m;
  
  	return NULL;
  }

  static struct component *find_component(struct master *master,

  	int (*compare)(struct device *, void *), void *compare_data)
  {
  	struct component *c;

  
  	list_for_each_entry(c, &component_list, node) {

  		if (c->master && c->master != master)

  			continue;

  		if (compare(c->dev, compare_data))
  			return c;

  	}

  	return NULL;

  }

  static int find_components(struct master *master)
  {
  	struct component_match *match = master->match;
  	size_t i;
  	int ret = 0;

  	/*
  	 * Scan the array of match functions and attach
  	 * any components which are found to this master.
  	 */
  	for (i = 0; i < match->num; i++) {

  		struct component_match_array *mc = &match->compare[i];

  		struct component *c;
  
  		dev_dbg(master->dev, "Looking for component %zu
  ", i);
  
  		if (match->compare[i].component)
  			continue;

  		c = find_component(master, mc->compare, mc->data);

  		if (!c) {
  			ret = -ENXIO;

  			break;

  		}
  
  		dev_dbg(master->dev, "found component %s, duplicate %u
  ", dev_name(c->dev), !!c->master);
  
  		/* Attach this component to the master */
  		match->compare[i].duplicate = !!c->master;
  		match->compare[i].component = c;
  		c->master = master;

  	}
  	return ret;
  }

  /* Detach component from associated master */
  static void remove_component(struct master *master, struct component *c)

  {

  	size_t i;

  	/* Detach the component from this master. */
  	for (i = 0; i < master->match->num; i++)
  		if (master->match->compare[i].component == c)
  			master->match->compare[i].component = NULL;

  }
  
  /*
   * Try to bring up a master.  If component is NULL, we're interested in
   * this master, otherwise it's a component which must be present to try
   * and bring up the master.
   *
   * Returns 1 for successful bringup, 0 if not ready, or -ve errno.
   */
  static int try_to_bring_up_master(struct master *master,
  	struct component *component)
  {

  	int ret;

  	dev_dbg(master->dev, "trying to bring up master
  ");

  	if (find_components(master)) {

  		dev_dbg(master->dev, "master has incomplete components
  ");
  		return 0;

  	}

  	if (component && component->master != master) {

  		dev_dbg(master->dev, "master is not for this component (%s)
  ",
  			dev_name(component->dev));
  		return 0;

  	}

  	if (!devres_open_group(master->dev, NULL, GFP_KERNEL))
  		return -ENOMEM;

  	/* Found all components */
  	ret = master->ops->bind(master->dev);
  	if (ret < 0) {
  		devres_release_group(master->dev, NULL);
  		dev_info(master->dev, "master bind failed: %d
  ", ret);

  		return ret;

  	}

  	master->bound = true;
  	return 1;

  }
  
  static int try_to_bring_up_masters(struct component *component)
  {
  	struct master *m;
  	int ret = 0;
  
  	list_for_each_entry(m, &masters, node) {

  		if (!m->bound) {
  			ret = try_to_bring_up_master(m, component);
  			if (ret != 0)
  				break;
  		}

  	}
  
  	return ret;
  }
  
  static void take_down_master(struct master *master)
  {
  	if (master->bound) {
  		master->ops->unbind(master->dev);

  		devres_release_group(master->dev, NULL);

  		master->bound = false;
  	}

  }

  static void component_match_release(struct device *master,
  	struct component_match *match)

  {

  	unsigned int i;
  
  	for (i = 0; i < match->num; i++) {
  		struct component_match_array *mc = &match->compare[i];
  
  		if (mc->release)
  			mc->release(master, mc->data);
  	}

  
  	kfree(match->compare);

  }

  static void devm_component_match_release(struct device *dev, void *res)
  {
  	component_match_release(dev, res);
  }
  
  static int component_match_realloc(struct device *dev,

  	struct component_match *match, size_t num)
  {

  	struct component_match_array *new;

  	if (match->alloc == num)
  		return 0;

  	new = kmalloc_array(num, sizeof(*new), GFP_KERNEL);

  	if (!new)

  		return -ENOMEM;

  	if (match->compare) {
  		memcpy(new, match->compare, sizeof(*new) *
  					    min(match->num, num));

  		kfree(match->compare);

  	}

  	match->compare = new;
  	match->alloc = num;

  	return 0;

  }
  
  /*

   * Add a component to be matched, with a release function.

   *
   * The match array is first created or extended if necessary.
   */

  void component_match_add_release(struct device *master,
  	struct component_match **matchptr,
  	void (*release)(struct device *, void *),

  	int (*compare)(struct device *, void *), void *compare_data)
  {
  	struct component_match *match = *matchptr;
  
  	if (IS_ERR(match))
  		return;

  	if (!match) {
  		match = devres_alloc(devm_component_match_release,
  				     sizeof(*match), GFP_KERNEL);
  		if (!match) {
  			*matchptr = ERR_PTR(-ENOMEM);
  			return;
  		}

  		devres_add(master, match);

  
  		*matchptr = match;

  	}

  	if (match->num == match->alloc) {

  		size_t new_size = match->alloc + 16;

  		int ret;
  
  		ret = component_match_realloc(master, match, new_size);
  		if (ret) {
  			*matchptr = ERR_PTR(ret);

  			return;

  		}

  	}

  	match->compare[match->num].compare = compare;
  	match->compare[match->num].release = release;

  	match->compare[match->num].data = compare_data;

  	match->compare[match->num].component = NULL;

  	match->num++;
  }

  EXPORT_SYMBOL(component_match_add_release);

  static void free_master(struct master *master)
  {
  	struct component_match *match = master->match;
  	int i;
  
  	list_del(&master->node);
  
  	if (match) {
  		for (i = 0; i < match->num; i++) {
  			struct component *c = match->compare[i].component;
  			if (c)
  				c->master = NULL;
  		}
  	}
  
  	kfree(master);
  }

  int component_master_add_with_match(struct device *dev,
  	const struct component_master_ops *ops,
  	struct component_match *match)

  {
  	struct master *master;
  	int ret;

  	/* Reallocate the match array for its true size */

  	ret = component_match_realloc(dev, match, match->num);
  	if (ret)
  		return ret;

  	master = kzalloc(sizeof(*master), GFP_KERNEL);
  	if (!master)
  		return -ENOMEM;
  
  	master->dev = dev;
  	master->ops = ops;

  	master->match = match;

  
  	/* Add to the list of available masters. */
  	mutex_lock(&component_mutex);
  	list_add(&master->node, &masters);
  
  	ret = try_to_bring_up_master(master, NULL);

  	if (ret < 0)
  		free_master(master);

  	mutex_unlock(&component_mutex);
  
  	return ret < 0 ? ret : 0;
  }

  EXPORT_SYMBOL_GPL(component_master_add_with_match);

  void component_master_del(struct device *dev,
  	const struct component_master_ops *ops)
  {
  	struct master *master;
  
  	mutex_lock(&component_mutex);
  	master = __master_find(dev, ops);
  	if (master) {
  		take_down_master(master);

  		free_master(master);

  	}
  	mutex_unlock(&component_mutex);
  }
  EXPORT_SYMBOL_GPL(component_master_del);
  
  static void component_unbind(struct component *component,
  	struct master *master, void *data)
  {
  	WARN_ON(!component->bound);
  
  	component->ops->unbind(component->dev, master->dev, data);
  	component->bound = false;
  
  	/* Release all resources claimed in the binding of this component */
  	devres_release_group(component->dev, component);
  }
  
  void component_unbind_all(struct device *master_dev, void *data)
  {
  	struct master *master;
  	struct component *c;

  	size_t i;

  
  	WARN_ON(!mutex_is_locked(&component_mutex));
  
  	master = __master_find(master_dev, NULL);
  	if (!master)
  		return;

  	/* Unbind components in reverse order */
  	for (i = master->match->num; i--; )
  		if (!master->match->compare[i].duplicate) {
  			c = master->match->compare[i].component;
  			component_unbind(c, master, data);
  		}

  }
  EXPORT_SYMBOL_GPL(component_unbind_all);
  
  static int component_bind(struct component *component, struct master *master,
  	void *data)
  {
  	int ret;
  
  	/*
  	 * Each component initialises inside its own devres group.
  	 * This allows us to roll-back a failed component without
  	 * affecting anything else.
  	 */
  	if (!devres_open_group(master->dev, NULL, GFP_KERNEL))
  		return -ENOMEM;
  
  	/*
  	 * Also open a group for the device itself: this allows us
  	 * to release the resources claimed against the sub-device
  	 * at the appropriate moment.
  	 */
  	if (!devres_open_group(component->dev, component, GFP_KERNEL)) {
  		devres_release_group(master->dev, NULL);
  		return -ENOMEM;
  	}
  
  	dev_dbg(master->dev, "binding %s (ops %ps)
  ",
  		dev_name(component->dev), component->ops);
  
  	ret = component->ops->bind(component->dev, master->dev, data);
  	if (!ret) {
  		component->bound = true;
  
  		/*
  		 * Close the component device's group so that resources
  		 * allocated in the binding are encapsulated for removal
  		 * at unbind.  Remove the group on the DRM device as we
  		 * can clean those resources up independently.
  		 */
  		devres_close_group(component->dev, NULL);
  		devres_remove_group(master->dev, NULL);
  
  		dev_info(master->dev, "bound %s (ops %ps)
  ",
  			 dev_name(component->dev), component->ops);
  	} else {
  		devres_release_group(component->dev, NULL);
  		devres_release_group(master->dev, NULL);
  
  		dev_err(master->dev, "failed to bind %s (ops %ps): %d
  ",
  			dev_name(component->dev), component->ops, ret);
  	}
  
  	return ret;
  }
  
  int component_bind_all(struct device *master_dev, void *data)
  {
  	struct master *master;
  	struct component *c;

  	size_t i;

  	int ret = 0;
  
  	WARN_ON(!mutex_is_locked(&component_mutex));
  
  	master = __master_find(master_dev, NULL);
  	if (!master)
  		return -EINVAL;

  	/* Bind components in match order */
  	for (i = 0; i < master->match->num; i++)
  		if (!master->match->compare[i].duplicate) {
  			c = master->match->compare[i].component;
  			ret = component_bind(c, master, data);
  			if (ret)
  				break;
  		}

  
  	if (ret != 0) {

  		for (; i--; )
  			if (!master->match->compare[i].duplicate) {
  				c = master->match->compare[i].component;
  				component_unbind(c, master, data);
  			}

  	}
  
  	return ret;
  }
  EXPORT_SYMBOL_GPL(component_bind_all);
  
  int component_add(struct device *dev, const struct component_ops *ops)
  {
  	struct component *component;
  	int ret;
  
  	component = kzalloc(sizeof(*component), GFP_KERNEL);
  	if (!component)
  		return -ENOMEM;
  
  	component->ops = ops;
  	component->dev = dev;
  
  	dev_dbg(dev, "adding component (ops %ps)
  ", ops);
  
  	mutex_lock(&component_mutex);
  	list_add_tail(&component->node, &component_list);
  
  	ret = try_to_bring_up_masters(component);
  	if (ret < 0) {

  		if (component->master)
  			remove_component(component->master, component);

  		list_del(&component->node);
  
  		kfree(component);
  	}
  	mutex_unlock(&component_mutex);
  
  	return ret < 0 ? ret : 0;
  }
  EXPORT_SYMBOL_GPL(component_add);
  
  void component_del(struct device *dev, const struct component_ops *ops)
  {
  	struct component *c, *component = NULL;
  
  	mutex_lock(&component_mutex);
  	list_for_each_entry(c, &component_list, node)
  		if (c->dev == dev && c->ops == ops) {
  			list_del(&c->node);
  			component = c;
  			break;
  		}

  	if (component && component->master) {

  		take_down_master(component->master);

  		remove_component(component->master, component);
  	}

  
  	mutex_unlock(&component_mutex);
  
  	WARN_ON(!component);
  	kfree(component);
  }
  EXPORT_SYMBOL_GPL(component_del);
  
  MODULE_LICENSE("GPL v2");