/*
   * Media device
   *
   * Copyright (C) 2010 Nokia Corporation
   *
   * Contacts: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
   *	     Sakari Ailus <sakari.ailus@iki.fi>
   *
   * 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 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.

   */

  /* We need to access legacy defines from linux/media.h */
  #define __NEED_MEDIA_LEGACY_API

  #include <linux/compat.h>
  #include <linux/export.h>

  #include <linux/idr.h>

  #include <linux/ioctl.h>

  #include <linux/media.h>

  #include <linux/slab.h>

  #include <linux/types.h>

  #include <linux/pci.h>
  #include <linux/usb.h>

  
  #include <media/media-device.h>
  #include <media/media-devnode.h>

  #include <media/media-entity.h>

  #ifdef CONFIG_MEDIA_CONTROLLER

  /* -----------------------------------------------------------------------------
   * Userspace API
   */

  static inline void __user *media_get_uptr(__u64 arg)
  {
  	return (void __user *)(uintptr_t)arg;
  }

  static int media_device_open(struct file *filp)
  {
  	return 0;
  }
  
  static int media_device_close(struct file *filp)
  {
  	return 0;
  }

  static long media_device_get_info(struct media_device *dev, void *arg)

  {

  	struct media_device_info *info = arg;

  	memset(info, 0, sizeof(*info));

  	if (dev->driver_name[0])

  		strlcpy(info->driver, dev->driver_name, sizeof(info->driver));

  	else

  		strlcpy(info->driver, dev->dev->driver->name,
  			sizeof(info->driver));

  	strlcpy(info->model, dev->model, sizeof(info->model));
  	strlcpy(info->serial, dev->serial, sizeof(info->serial));
  	strlcpy(info->bus_info, dev->bus_info, sizeof(info->bus_info));

  	info->media_version = LINUX_VERSION_CODE;
  	info->driver_version = info->media_version;

  	info->hw_revision = dev->hw_revision;

  	return 0;

  }

  static struct media_entity *find_entity(struct media_device *mdev, u32 id)
  {
  	struct media_entity *entity;
  	int next = id & MEDIA_ENT_ID_FLAG_NEXT;
  
  	id &= ~MEDIA_ENT_ID_FLAG_NEXT;

  	media_device_for_each_entity(entity, mdev) {

  		if (((media_entity_id(entity) == id) && !next) ||
  		    ((media_entity_id(entity) > id) && next)) {

  			return entity;
  		}
  	}

  	return NULL;
  }

  static long media_device_enum_entities(struct media_device *mdev, void *arg)

  {

  	struct media_entity_desc *entd = arg;

  	struct media_entity *ent;

  	ent = find_entity(mdev, entd->id);

  	if (ent == NULL)
  		return -EINVAL;

  	memset(entd, 0, sizeof(*entd));
  
  	entd->id = media_entity_id(ent);

  	if (ent->name)

  		strlcpy(entd->name, ent->name, sizeof(entd->name));
  	entd->type = ent->function;
  	entd->revision = 0;		/* Unused */
  	entd->flags = ent->flags;
  	entd->group_id = 0;		/* Unused */
  	entd->pads = ent->num_pads;
  	entd->links = ent->num_links - ent->num_backlinks;

  
  	/*
  	 * Workaround for a bug at media-ctl <= v1.10 that makes it to
  	 * do the wrong thing if the entity function doesn't belong to
  	 * either MEDIA_ENT_F_OLD_BASE or MEDIA_ENT_F_OLD_SUBDEV_BASE
  	 * Ranges.
  	 *
  	 * Non-subdevices are expected to be at the MEDIA_ENT_F_OLD_BASE,
  	 * or, otherwise, will be silently ignored by media-ctl when
  	 * printing the graphviz diagram. So, map them into the devnode
  	 * old range.
  	 */
  	if (ent->function < MEDIA_ENT_F_OLD_BASE ||

  	    ent->function > MEDIA_ENT_F_TUNER) {

  		if (is_media_entity_v4l2_subdev(ent))

  			entd->type = MEDIA_ENT_F_V4L2_SUBDEV_UNKNOWN;

  		else if (ent->function != MEDIA_ENT_F_IO_V4L)

  			entd->type = MEDIA_ENT_T_DEVNODE_UNKNOWN;

  	}

  	memcpy(&entd->raw, &ent->info, sizeof(ent->info));

  	return 0;
  }
  
  static void media_device_kpad_to_upad(const struct media_pad *kpad,
  				      struct media_pad_desc *upad)
  {

  	upad->entity = media_entity_id(kpad->entity);

  	upad->index = kpad->index;
  	upad->flags = kpad->flags;
  }

  static long media_device_enum_links(struct media_device *mdev, void *arg)

  {

  	struct media_links_enum *links = arg;

  	struct media_entity *entity;

  	entity = find_entity(mdev, links->entity);

  	if (entity == NULL)
  		return -EINVAL;

  	if (links->pads) {

  		unsigned int p;
  
  		for (p = 0; p < entity->num_pads; p++) {
  			struct media_pad_desc pad;

  
  			memset(&pad, 0, sizeof(pad));

  			media_device_kpad_to_upad(&entity->pads[p], &pad);

  			if (copy_to_user(&links->pads[p], &pad, sizeof(pad)))

  				return -EFAULT;
  		}
  	}

  	if (links->links) {

  		struct media_link *link;
  		struct media_link_desc __user *ulink_desc = links->links;

  		list_for_each_entry(link, &entity->links, list) {
  			struct media_link_desc klink_desc;

  
  			/* Ignore backlinks. */

  			if (link->source->entity != entity)

  				continue;

  			memset(&klink_desc, 0, sizeof(klink_desc));
  			media_device_kpad_to_upad(link->source,
  						  &klink_desc.source);
  			media_device_kpad_to_upad(link->sink,
  						  &klink_desc.sink);
  			klink_desc.flags = link->flags;
  			if (copy_to_user(ulink_desc, &klink_desc,
  					 sizeof(*ulink_desc)))

  				return -EFAULT;

  			ulink_desc++;

  		}
  	}

  
  	return 0;
  }

  static long media_device_setup_link(struct media_device *mdev, void *arg)

  {

  	struct media_link_desc *linkd = arg;

  	struct media_link *link = NULL;

  	struct media_entity *source;
  	struct media_entity *sink;

  
  	/* Find the source and sink entities and link.
  	 */

  	source = find_entity(mdev, linkd->source.entity);
  	sink = find_entity(mdev, linkd->sink.entity);

  
  	if (source == NULL || sink == NULL)
  		return -EINVAL;

  	if (linkd->source.index >= source->num_pads ||
  	    linkd->sink.index >= sink->num_pads)

  		return -EINVAL;

  	link = media_entity_find_link(&source->pads[linkd->source.index],
  				      &sink->pads[linkd->sink.index]);

  	if (link == NULL)
  		return -EINVAL;
  
  	/* Setup the link on both entities. */

  	return __media_entity_setup_link(link, linkd->flags);

  }

  static long media_device_get_topology(struct media_device *mdev, void *arg)

  {

  	struct media_v2_topology *topo = arg;

  	struct media_entity *entity;
  	struct media_interface *intf;
  	struct media_pad *pad;
  	struct media_link *link;

  	struct media_v2_entity kentity, __user *uentity;
  	struct media_v2_interface kintf, __user *uintf;
  	struct media_v2_pad kpad, __user *upad;
  	struct media_v2_link klink, __user *ulink;

  	unsigned int i;
  	int ret = 0;

  
  	topo->topology_version = mdev->topology_version;
  
  	/* Get entities and number of entities */
  	i = 0;

  	uentity = media_get_uptr(topo->ptr_entities);

  	media_device_for_each_entity(entity, mdev) {
  		i++;

  		if (ret || !uentity)

  			continue;
  
  		if (i > topo->num_entities) {
  			ret = -ENOSPC;
  			continue;
  		}
  
  		/* Copy fields to userspace struct if not error */

  		memset(&kentity, 0, sizeof(kentity));
  		kentity.id = entity->graph_obj.id;
  		kentity.function = entity->function;
  		strncpy(kentity.name, entity->name,
  			sizeof(kentity.name));

  		if (copy_to_user(uentity, &kentity, sizeof(kentity)))

  			ret = -EFAULT;

  		uentity++;

  	}
  	topo->num_entities = i;
  
  	/* Get interfaces and number of interfaces */
  	i = 0;

  	uintf = media_get_uptr(topo->ptr_interfaces);

  	media_device_for_each_intf(intf, mdev) {
  		i++;

  		if (ret || !uintf)

  			continue;
  
  		if (i > topo->num_interfaces) {
  			ret = -ENOSPC;
  			continue;
  		}

  		memset(&kintf, 0, sizeof(kintf));

  
  		/* Copy intf fields to userspace struct */

  		kintf.id = intf->graph_obj.id;
  		kintf.intf_type = intf->type;
  		kintf.flags = intf->flags;

  
  		if (media_type(&intf->graph_obj) == MEDIA_GRAPH_INTF_DEVNODE) {
  			struct media_intf_devnode *devnode;
  
  			devnode = intf_to_devnode(intf);

  			kintf.devnode.major = devnode->major;
  			kintf.devnode.minor = devnode->minor;

  		}

  		if (copy_to_user(uintf, &kintf, sizeof(kintf)))

  			ret = -EFAULT;

  		uintf++;

  	}
  	topo->num_interfaces = i;
  
  	/* Get pads and number of pads */
  	i = 0;

  	upad = media_get_uptr(topo->ptr_pads);

  	media_device_for_each_pad(pad, mdev) {
  		i++;

  		if (ret || !upad)

  			continue;
  
  		if (i > topo->num_pads) {
  			ret = -ENOSPC;
  			continue;
  		}

  		memset(&kpad, 0, sizeof(kpad));

  
  		/* Copy pad fields to userspace struct */

  		kpad.id = pad->graph_obj.id;
  		kpad.entity_id = pad->entity->graph_obj.id;
  		kpad.flags = pad->flags;

  		if (copy_to_user(upad, &kpad, sizeof(kpad)))

  			ret = -EFAULT;

  		upad++;

  	}
  	topo->num_pads = i;
  
  	/* Get links and number of links */
  	i = 0;

  	ulink = media_get_uptr(topo->ptr_links);

  	media_device_for_each_link(link, mdev) {

  		if (link->is_backlink)
  			continue;

  		i++;

  		if (ret || !ulink)

  			continue;
  
  		if (i > topo->num_links) {
  			ret = -ENOSPC;
  			continue;
  		}

  		memset(&klink, 0, sizeof(klink));

  
  		/* Copy link fields to userspace struct */

  		klink.id = link->graph_obj.id;
  		klink.source_id = link->gobj0->id;
  		klink.sink_id = link->gobj1->id;
  		klink.flags = link->flags;

  		if (copy_to_user(ulink, &klink, sizeof(klink)))

  			ret = -EFAULT;

  		ulink++;

  	}
  	topo->num_links = i;
  
  	return ret;
  }

  static long copy_arg_from_user(void *karg, void __user *uarg, unsigned int cmd)

  {

  	/* All media IOCTLs are _IOWR() */
  	if (copy_from_user(karg, uarg, _IOC_SIZE(cmd)))

  		return -EFAULT;

  	return 0;
  }

  static long copy_arg_to_user(void __user *uarg, void *karg, unsigned int cmd)
  {
  	/* All media IOCTLs are _IOWR() */
  	if (copy_to_user(uarg, karg, _IOC_SIZE(cmd)))

  		return -EFAULT;

  	return 0;

  }

  /* Do acquire the graph mutex */
  #define MEDIA_IOC_FL_GRAPH_MUTEX	BIT(0)
  
  #define MEDIA_IOC_ARG(__cmd, func, fl, from_user, to_user)		\
  	[_IOC_NR(MEDIA_IOC_##__cmd)] = {				\
  		.cmd = MEDIA_IOC_##__cmd,				\

  		.fn = (long (*)(struct media_device *, void *))func,	\

  		.flags = fl,						\
  		.arg_from_user = from_user,				\
  		.arg_to_user = to_user,					\

  	}

  #define MEDIA_IOC(__cmd, func, fl)					\
  	MEDIA_IOC_ARG(__cmd, func, fl, copy_arg_from_user, copy_arg_to_user)

  /* the table is indexed by _IOC_NR(cmd) */
  struct media_ioctl_info {
  	unsigned int cmd;

  	unsigned short flags;

  	long (*fn)(struct media_device *dev, void *arg);
  	long (*arg_from_user)(void *karg, void __user *uarg, unsigned int cmd);
  	long (*arg_to_user)(void __user *uarg, void *karg, unsigned int cmd);

  };
  
  static const struct media_ioctl_info ioctl_info[] = {

  	MEDIA_IOC(DEVICE_INFO, media_device_get_info, MEDIA_IOC_FL_GRAPH_MUTEX),
  	MEDIA_IOC(ENUM_ENTITIES, media_device_enum_entities, MEDIA_IOC_FL_GRAPH_MUTEX),
  	MEDIA_IOC(ENUM_LINKS, media_device_enum_links, MEDIA_IOC_FL_GRAPH_MUTEX),
  	MEDIA_IOC(SETUP_LINK, media_device_setup_link, MEDIA_IOC_FL_GRAPH_MUTEX),
  	MEDIA_IOC(G_TOPOLOGY, media_device_get_topology, MEDIA_IOC_FL_GRAPH_MUTEX),

  };

  static long media_device_ioctl(struct file *filp, unsigned int cmd,

  			       unsigned long __arg)

  {
  	struct media_devnode *devnode = media_devnode_data(filp);

  	struct media_device *dev = devnode->media_dev;

  	const struct media_ioctl_info *info;

  	void __user *arg = (void __user *)__arg;
  	char __karg[256], *karg = __karg;

  	long ret;

  	if (_IOC_NR(cmd) >= ARRAY_SIZE(ioctl_info)
  	    || ioctl_info[_IOC_NR(cmd)].cmd != cmd)
  		return -ENOIOCTLCMD;

  	info = &ioctl_info[_IOC_NR(cmd)];

  	if (_IOC_SIZE(info->cmd) > sizeof(__karg)) {
  		karg = kmalloc(_IOC_SIZE(info->cmd), GFP_KERNEL);
  		if (!karg)
  			return -ENOMEM;
  	}
  
  	if (info->arg_from_user) {
  		ret = info->arg_from_user(karg, arg, cmd);
  		if (ret)
  			goto out_free;
  	}

  	if (info->flags & MEDIA_IOC_FL_GRAPH_MUTEX)
  		mutex_lock(&dev->graph_mutex);

  	ret = info->fn(dev, karg);

  
  	if (info->flags & MEDIA_IOC_FL_GRAPH_MUTEX)
  		mutex_unlock(&dev->graph_mutex);

  	if (!ret && info->arg_to_user)
  		ret = info->arg_to_user(arg, karg, cmd);
  
  out_free:
  	if (karg != __karg)
  		kfree(karg);

  	return ret;
  }

  #ifdef CONFIG_COMPAT
  
  struct media_links_enum32 {
  	__u32 entity;
  	compat_uptr_t pads; /* struct media_pad_desc * */
  	compat_uptr_t links; /* struct media_link_desc * */
  	__u32 reserved[4];
  };
  
  static long media_device_enum_links32(struct media_device *mdev,
  				      struct media_links_enum32 __user *ulinks)
  {
  	struct media_links_enum links;
  	compat_uptr_t pads_ptr, links_ptr;
  
  	memset(&links, 0, sizeof(links));
  
  	if (get_user(links.entity, &ulinks->entity)
  	    || get_user(pads_ptr, &ulinks->pads)
  	    || get_user(links_ptr, &ulinks->links))
  		return -EFAULT;
  
  	links.pads = compat_ptr(pads_ptr);
  	links.links = compat_ptr(links_ptr);

  	return media_device_enum_links(mdev, &links);

  }
  
  #define MEDIA_IOC_ENUM_LINKS32		_IOWR('|', 0x02, struct media_links_enum32)
  
  static long media_device_compat_ioctl(struct file *filp, unsigned int cmd,
  				      unsigned long arg)
  {
  	struct media_devnode *devnode = media_devnode_data(filp);

  	struct media_device *dev = devnode->media_dev;

  	long ret;
  
  	switch (cmd) {

  	case MEDIA_IOC_ENUM_LINKS32:
  		mutex_lock(&dev->graph_mutex);
  		ret = media_device_enum_links32(dev,
  				(struct media_links_enum32 __user *)arg);
  		mutex_unlock(&dev->graph_mutex);
  		break;
  
  	default:

  		return media_device_ioctl(filp, cmd, arg);

  	}
  
  	return ret;
  }
  #endif /* CONFIG_COMPAT */

  static const struct media_file_operations media_device_fops = {
  	.owner = THIS_MODULE,

  	.open = media_device_open,
  	.ioctl = media_device_ioctl,

  #ifdef CONFIG_COMPAT
  	.compat_ioctl = media_device_compat_ioctl,
  #endif /* CONFIG_COMPAT */

  	.release = media_device_close,

  };
  
  /* -----------------------------------------------------------------------------
   * sysfs
   */
  
  static ssize_t show_model(struct device *cd,
  			  struct device_attribute *attr, char *buf)
  {

  	struct media_devnode *devnode = to_media_devnode(cd);
  	struct media_device *mdev = devnode->media_dev;

  
  	return sprintf(buf, "%.*s
  ", (int)sizeof(mdev->model), mdev->model);
  }
  
  static DEVICE_ATTR(model, S_IRUGO, show_model, NULL);
  
  /* -----------------------------------------------------------------------------
   * Registration/unregistration
   */

  static void media_device_release(struct media_devnode *devnode)

  {

  	dev_dbg(devnode->parent, "Media device released
  ");

  }
  
  /**

   * media_device_register_entity - Register an entity with a media device
   * @mdev:	The media device
   * @entity:	The entity
   */
  int __must_check media_device_register_entity(struct media_device *mdev,
  					      struct media_entity *entity)
  {

  	struct media_entity_notify *notify, *next;

  	unsigned int i;

  	int ret;

  
  	if (entity->function == MEDIA_ENT_F_V4L2_SUBDEV_UNKNOWN ||
  	    entity->function == MEDIA_ENT_F_UNKNOWN)
  		dev_warn(mdev->dev,
  			 "Entity type for entity %s was not initialized!
  ",
  			 entity->name);
  
  	/* Warn if we apparently re-register an entity */
  	WARN_ON(entity->graph_obj.mdev != NULL);
  	entity->graph_obj.mdev = mdev;
  	INIT_LIST_HEAD(&entity->links);
  	entity->num_links = 0;
  	entity->num_backlinks = 0;

  	if (!ida_pre_get(&mdev->entity_internal_idx, GFP_KERNEL))
  		return -ENOMEM;

  	mutex_lock(&mdev->graph_mutex);

  	ret = ida_get_new_above(&mdev->entity_internal_idx, 1,
  				&entity->internal_idx);
  	if (ret < 0) {

  		mutex_unlock(&mdev->graph_mutex);

  		return ret;

  	}
  
  	mdev->entity_internal_idx_max =
  		max(mdev->entity_internal_idx_max, entity->internal_idx);

  	/* Initialize media_gobj embedded at the entity */
  	media_gobj_create(mdev, MEDIA_GRAPH_ENTITY, &entity->graph_obj);
  
  	/* Initialize objects at the pads */
  	for (i = 0; i < entity->num_pads; i++)
  		media_gobj_create(mdev, MEDIA_GRAPH_PAD,
  			       &entity->pads[i].graph_obj);

  	/* invoke entity_notify callbacks */

  	list_for_each_entry_safe(notify, next, &mdev->entity_notify, list)
  		notify->notify(entity, notify->notify_data);

  	if (mdev->entity_internal_idx_max
  	    >= mdev->pm_count_walk.ent_enum.idx_max) {

  		struct media_graph new = { .top = 0 };

  
  		/*
  		 * Initialise the new graph walk before cleaning up
  		 * the old one in order not to spoil the graph walk
  		 * object of the media device if graph walk init fails.
  		 */

  		ret = media_graph_walk_init(&new, mdev);

  		if (ret) {
  			mutex_unlock(&mdev->graph_mutex);
  			return ret;
  		}

  		media_graph_walk_cleanup(&mdev->pm_count_walk);

  		mdev->pm_count_walk = new;
  	}
  	mutex_unlock(&mdev->graph_mutex);

  	return 0;
  }
  EXPORT_SYMBOL_GPL(media_device_register_entity);

  static void __media_device_unregister_entity(struct media_entity *entity)

  {
  	struct media_device *mdev = entity->graph_obj.mdev;
  	struct media_link *link, *tmp;
  	struct media_interface *intf;
  	unsigned int i;

  	ida_simple_remove(&mdev->entity_internal_idx, entity->internal_idx);

  	/* Remove all interface links pointing to this entity */
  	list_for_each_entry(intf, &mdev->interfaces, graph_obj.list) {
  		list_for_each_entry_safe(link, tmp, &intf->links, list) {
  			if (link->entity == entity)
  				__media_remove_intf_link(link);
  		}
  	}
  
  	/* Remove all data links that belong to this entity */
  	__media_entity_remove_links(entity);
  
  	/* Remove all pads that belong to this entity */
  	for (i = 0; i < entity->num_pads; i++)
  		media_gobj_destroy(&entity->pads[i].graph_obj);
  
  	/* Remove the entity */
  	media_gobj_destroy(&entity->graph_obj);

  	/* invoke entity_notify callbacks to handle entity removal?? */

  	entity->graph_obj.mdev = NULL;
  }

  
  void media_device_unregister_entity(struct media_entity *entity)
  {
  	struct media_device *mdev = entity->graph_obj.mdev;
  
  	if (mdev == NULL)
  		return;

  	mutex_lock(&mdev->graph_mutex);

  	__media_device_unregister_entity(entity);

  	mutex_unlock(&mdev->graph_mutex);

  }

  EXPORT_SYMBOL_GPL(media_device_unregister_entity);
  
  /**

   * media_device_init() - initialize a media device

   * @mdev:	The media device
   *
   * The caller is responsible for initializing the media device before
   * registration. The following fields must be set:
   *
   * - dev must point to the parent device
   * - model must be filled with the device model name
   */

  void media_device_init(struct media_device *mdev)

  {

  	INIT_LIST_HEAD(&mdev->entities);

  	INIT_LIST_HEAD(&mdev->interfaces);

  	INIT_LIST_HEAD(&mdev->pads);
  	INIT_LIST_HEAD(&mdev->links);

  	INIT_LIST_HEAD(&mdev->entity_notify);

  	mutex_init(&mdev->graph_mutex);

  	ida_init(&mdev->entity_internal_idx);

  	dev_dbg(mdev->dev, "Media device initialized
  ");
  }
  EXPORT_SYMBOL_GPL(media_device_init);

  void media_device_cleanup(struct media_device *mdev)
  {

  	ida_destroy(&mdev->entity_internal_idx);
  	mdev->entity_internal_idx_max = 0;

  	media_graph_walk_cleanup(&mdev->pm_count_walk);

  	mutex_destroy(&mdev->graph_mutex);
  }
  EXPORT_SYMBOL_GPL(media_device_cleanup);

  int __must_check __media_device_register(struct media_device *mdev,
  					 struct module *owner)
  {

  	struct media_devnode *devnode;

  	int ret;

  	devnode = kzalloc(sizeof(*devnode), GFP_KERNEL);
  	if (!devnode)
  		return -ENOMEM;

  	/* Register the device node. */

  	mdev->devnode = devnode;
  	devnode->fops = &media_device_fops;
  	devnode->parent = mdev->dev;
  	devnode->release = media_device_release;

  
  	/* Set version 0 to indicate user-space that the graph is static */
  	mdev->topology_version = 0;

  	ret = media_devnode_register(mdev, devnode, owner);
  	if (ret < 0) {

  		/* devnode free is handled in media_devnode_*() */

  		mdev->devnode = NULL;

  		return ret;

  	}

  	ret = device_create_file(&devnode->dev, &dev_attr_model);

  	if (ret < 0) {

  		/* devnode free is handled in media_devnode_*() */

  		mdev->devnode = NULL;

  		media_devnode_unregister_prepare(devnode);

  		media_devnode_unregister(devnode);

  		return ret;
  	}

  	dev_dbg(mdev->dev, "Media device registered
  ");

  	return 0;
  }

  EXPORT_SYMBOL_GPL(__media_device_register);

  int __must_check media_device_register_entity_notify(struct media_device *mdev,
  					struct media_entity_notify *nptr)
  {

  	mutex_lock(&mdev->graph_mutex);

  	list_add_tail(&nptr->list, &mdev->entity_notify);

  	mutex_unlock(&mdev->graph_mutex);

  	return 0;
  }
  EXPORT_SYMBOL_GPL(media_device_register_entity_notify);
  
  /*
   * Note: Should be called with mdev->lock held.
   */
  static void __media_device_unregister_entity_notify(struct media_device *mdev,
  					struct media_entity_notify *nptr)
  {
  	list_del(&nptr->list);
  }
  
  void media_device_unregister_entity_notify(struct media_device *mdev,
  					struct media_entity_notify *nptr)
  {

  	mutex_lock(&mdev->graph_mutex);

  	__media_device_unregister_entity_notify(mdev, nptr);

  	mutex_unlock(&mdev->graph_mutex);

  }
  EXPORT_SYMBOL_GPL(media_device_unregister_entity_notify);

  void media_device_unregister(struct media_device *mdev)
  {

  	struct media_entity *entity;
  	struct media_entity *next;

  	struct media_interface *intf, *tmp_intf;

  	struct media_entity_notify *notify, *nextp;

  	if (mdev == NULL)
  		return;

  	mutex_lock(&mdev->graph_mutex);

  	/* Check if mdev was ever registered at all */

  	if (!media_devnode_is_registered(mdev->devnode)) {

  		mutex_unlock(&mdev->graph_mutex);

  		return;

  	}

  	/* Clear the devnode register bit to avoid races with media dev open */
  	media_devnode_unregister_prepare(mdev->devnode);

  	/* Remove all entities from the media device */
  	list_for_each_entry_safe(entity, next, &mdev->entities, graph_obj.list)

  		__media_device_unregister_entity(entity);

  	/* Remove all entity_notify callbacks from the media device */
  	list_for_each_entry_safe(notify, nextp, &mdev->entity_notify, list)
  		__media_device_unregister_entity_notify(mdev, notify);

  	/* Remove all interfaces from the media device */

  	list_for_each_entry_safe(intf, tmp_intf, &mdev->interfaces,
  				 graph_obj.list) {

  		/*
  		 * Unlink the interface, but don't free it here; the
  		 * module which created it is responsible for freeing
  		 * it
  		 */

  		__media_remove_intf_links(intf);

  		media_gobj_destroy(&intf->graph_obj);

  	}

  	mutex_unlock(&mdev->graph_mutex);

  	dev_dbg(mdev->dev, "Media device unregistered
  ");

  	device_remove_file(&mdev->devnode->dev, &dev_attr_model);
  	media_devnode_unregister(mdev->devnode);
  	/* devnode free is handled in media_devnode_*() */
  	mdev->devnode = NULL;

  }
  EXPORT_SYMBOL_GPL(media_device_unregister);

  #if IS_ENABLED(CONFIG_PCI)

  void media_device_pci_init(struct media_device *mdev,
  			   struct pci_dev *pci_dev,
  			   const char *name)

  {

  	mdev->dev = &pci_dev->dev;
  
  	if (name)
  		strlcpy(mdev->model, name, sizeof(mdev->model));
  	else
  		strlcpy(mdev->model, pci_name(pci_dev), sizeof(mdev->model));
  
  	sprintf(mdev->bus_info, "PCI:%s", pci_name(pci_dev));
  
  	mdev->hw_revision = (pci_dev->subsystem_vendor << 16)
  			    | pci_dev->subsystem_device;

  	media_device_init(mdev);

  }
  EXPORT_SYMBOL_GPL(media_device_pci_init);

  #endif

  #if IS_ENABLED(CONFIG_USB)

  void __media_device_usb_init(struct media_device *mdev,
  			     struct usb_device *udev,
  			     const char *board_name,
  			     const char *driver_name)

  {

  	mdev->dev = &udev->dev;
  
  	if (driver_name)
  		strlcpy(mdev->driver_name, driver_name,
  			sizeof(mdev->driver_name));
  
  	if (board_name)
  		strlcpy(mdev->model, board_name, sizeof(mdev->model));
  	else if (udev->product)
  		strlcpy(mdev->model, udev->product, sizeof(mdev->model));
  	else
  		strlcpy(mdev->model, "unknown model", sizeof(mdev->model));
  	if (udev->serial)
  		strlcpy(mdev->serial, udev->serial, sizeof(mdev->serial));
  	usb_make_path(udev, mdev->bus_info, sizeof(mdev->bus_info));
  	mdev->hw_revision = le16_to_cpu(udev->descriptor.bcdDevice);

  
  	media_device_init(mdev);

  }
  EXPORT_SYMBOL_GPL(__media_device_usb_init);

  #endif

  #endif /* CONFIG_MEDIA_CONTROLLER */