/*

   * drivers/base/dd.c - The core device/driver interactions.

   *

   * This file contains the (sometimes tricky) code that controls the
   * interactions between devices and drivers, which primarily includes
   * driver binding and unbinding.

   *

   * All of this code used to exist in drivers/base/bus.c, but was
   * relocated to here in the name of compartmentalization (since it wasn't
   * strictly code just for the 'struct bus_type'.

   *

   * Copyright (c) 2002-5 Patrick Mochel
   * Copyright (c) 2002-3 Open Source Development Labs

   * Copyright (c) 2007-2009 Greg Kroah-Hartman <gregkh@suse.de>
   * Copyright (c) 2007-2009 Novell Inc.

   *

   * This file is released under the GPLv2

   */
  
  #include <linux/device.h>

  #include <linux/delay.h>

  #include <linux/module.h>

  #include <linux/kthread.h>

  #include <linux/wait.h>

  #include <linux/async.h>

  #include <linux/pm_runtime.h>

  #include <linux/pinctrl/devinfo.h>

  
  #include "base.h"
  #include "power/power.h"

  /*
   * Deferred Probe infrastructure.
   *
   * Sometimes driver probe order matters, but the kernel doesn't always have
   * dependency information which means some drivers will get probed before a
   * resource it depends on is available.  For example, an SDHCI driver may
   * first need a GPIO line from an i2c GPIO controller before it can be
   * initialized.  If a required resource is not available yet, a driver can
   * request probing to be deferred by returning -EPROBE_DEFER from its probe hook
   *
   * Deferred probe maintains two lists of devices, a pending list and an active
   * list.  A driver returning -EPROBE_DEFER causes the device to be added to the
   * pending list.  A successful driver probe will trigger moving all devices
   * from the pending to the active list so that the workqueue will eventually
   * retry them.
   *
   * The deferred_probe_mutex must be held any time the deferred_probe_*_list

   * of the (struct device*)->p->deferred_probe pointers are manipulated

   */
  static DEFINE_MUTEX(deferred_probe_mutex);
  static LIST_HEAD(deferred_probe_pending_list);
  static LIST_HEAD(deferred_probe_active_list);

  static atomic_t deferred_trigger_count = ATOMIC_INIT(0);

  /*

   * In some cases, like suspend to RAM or hibernation, It might be reasonable
   * to prohibit probing of devices as it could be unsafe.
   * Once defer_all_probes is true all drivers probes will be forcibly deferred.
   */
  static bool defer_all_probes;
  
  /*

   * deferred_probe_work_func() - Retry probing devices in the active list.
   */
  static void deferred_probe_work_func(struct work_struct *work)
  {
  	struct device *dev;

  	struct device_private *private;

  	/*
  	 * This block processes every device in the deferred 'active' list.
  	 * Each device is removed from the active list and passed to
  	 * bus_probe_device() to re-attempt the probe.  The loop continues
  	 * until every device in the active list is removed and retried.
  	 *
  	 * Note: Once the device is removed from the list and the mutex is
  	 * released, it is possible for the device get freed by another thread
  	 * and cause a illegal pointer dereference.  This code uses
  	 * get/put_device() to ensure the device structure cannot disappear
  	 * from under our feet.
  	 */
  	mutex_lock(&deferred_probe_mutex);
  	while (!list_empty(&deferred_probe_active_list)) {

  		private = list_first_entry(&deferred_probe_active_list,
  					typeof(*dev->p), deferred_probe);
  		dev = private->device;
  		list_del_init(&private->deferred_probe);

  
  		get_device(dev);

  		/*
  		 * Drop the mutex while probing each device; the probe path may
  		 * manipulate the deferred list
  		 */

  		mutex_unlock(&deferred_probe_mutex);

  
  		/*
  		 * Force the device to the end of the dpm_list since
  		 * the PM code assumes that the order we add things to
  		 * the list is a good order for suspend but deferred
  		 * probe makes that very unsafe.
  		 */
  		device_pm_lock();
  		device_pm_move_last(dev);
  		device_pm_unlock();

  		dev_dbg(dev, "Retrying from deferred list
  ");
  		bus_probe_device(dev);

  		mutex_lock(&deferred_probe_mutex);
  
  		put_device(dev);
  	}
  	mutex_unlock(&deferred_probe_mutex);
  }
  static DECLARE_WORK(deferred_probe_work, deferred_probe_work_func);
  
  static void driver_deferred_probe_add(struct device *dev)
  {
  	mutex_lock(&deferred_probe_mutex);

  	if (list_empty(&dev->p->deferred_probe)) {

  		dev_dbg(dev, "Added to deferred list
  ");

  		list_add_tail(&dev->p->deferred_probe, &deferred_probe_pending_list);

  	}
  	mutex_unlock(&deferred_probe_mutex);
  }
  
  void driver_deferred_probe_del(struct device *dev)
  {
  	mutex_lock(&deferred_probe_mutex);

  	if (!list_empty(&dev->p->deferred_probe)) {

  		dev_dbg(dev, "Removed from deferred list
  ");

  		list_del_init(&dev->p->deferred_probe);

  	}
  	mutex_unlock(&deferred_probe_mutex);
  }
  
  static bool driver_deferred_probe_enable = false;
  /**
   * driver_deferred_probe_trigger() - Kick off re-probing deferred devices
   *
   * This functions moves all devices from the pending list to the active
   * list and schedules the deferred probe workqueue to process them.  It
   * should be called anytime a driver is successfully bound to a device.

   *
   * Note, there is a race condition in multi-threaded probe. In the case where
   * more than one device is probing at the same time, it is possible for one
   * probe to complete successfully while another is about to defer. If the second
   * depends on the first, then it will get put on the pending list after the

   * trigger event has already occurred and will be stuck there.

   *
   * The atomic 'deferred_trigger_count' is used to determine if a successful
   * trigger has occurred in the midst of probing a driver. If the trigger count
   * changes in the midst of a probe, then deferred processing should be triggered
   * again.

   */
  static void driver_deferred_probe_trigger(void)
  {
  	if (!driver_deferred_probe_enable)
  		return;

  	/*
  	 * A successful probe means that all the devices in the pending list

  	 * should be triggered to be reprobed.  Move all the deferred devices

  	 * into the active list so they can be retried by the workqueue
  	 */

  	mutex_lock(&deferred_probe_mutex);

  	atomic_inc(&deferred_trigger_count);

  	list_splice_tail_init(&deferred_probe_pending_list,
  			      &deferred_probe_active_list);
  	mutex_unlock(&deferred_probe_mutex);

  	/*
  	 * Kick the re-probe thread.  It may already be scheduled, but it is
  	 * safe to kick it again.
  	 */

  	schedule_work(&deferred_probe_work);

  }
  
  /**

   * device_block_probing() - Block/defere device's probes
   *
   *	It will disable probing of devices and defer their probes instead.
   */
  void device_block_probing(void)
  {
  	defer_all_probes = true;
  	/* sync with probes to avoid races. */
  	wait_for_device_probe();
  }
  
  /**
   * device_unblock_probing() - Unblock/enable device's probes
   *
   *	It will restore normal behavior and trigger re-probing of deferred
   * devices.
   */
  void device_unblock_probing(void)
  {
  	defer_all_probes = false;
  	driver_deferred_probe_trigger();
  }
  
  /**

   * deferred_probe_initcall() - Enable probing of deferred devices
   *
   * We don't want to get in the way when the bulk of drivers are getting probed.
   * Instead, this initcall makes sure that deferred probing is delayed until
   * late_initcall time.
   */
  static int deferred_probe_initcall(void)
  {

  	driver_deferred_probe_enable = true;
  	driver_deferred_probe_trigger();

  	/* Sort as many dependencies as possible before exiting initcalls */

  	flush_work(&deferred_probe_work);

  	return 0;
  }
  late_initcall(deferred_probe_initcall);

  /**
   * device_is_bound() - Check if device is bound to a driver
   * @dev: device to check
   *
   * Returns true if passed device has already finished probing successfully
   * against a driver.
   *
   * This function must be called with the device lock held.
   */
  bool device_is_bound(struct device *dev)
  {

  	return dev->p && klist_node_attached(&dev->p->knode_driver);

  }

  static void driver_bound(struct device *dev)

  {

  	if (device_is_bound(dev)) {

  		printk(KERN_WARNING "%s: device %s already bound
  ",

  			__func__, kobject_name(&dev->kobj));

  		return;

  	}

  	pr_debug("driver: '%s': %s: bound to device '%s'
  ", dev->driver->name,
  		 __func__, dev_name(dev));

  	klist_add_tail(&dev->p->knode_driver, &dev->driver->p->klist_devices);

  	device_pm_check_callbacks(dev);

  	/*
  	 * Make sure the device is no longer in one of the deferred lists and
  	 * kick off retrying all pending devices
  	 */

  	driver_deferred_probe_del(dev);
  	driver_deferred_probe_trigger();

  	if (dev->bus)

  		blocking_notifier_call_chain(&dev->bus->p->bus_notifier,

  					     BUS_NOTIFY_BOUND_DRIVER, dev);

  }
  
  static int driver_sysfs_add(struct device *dev)
  {
  	int ret;

  	if (dev->bus)
  		blocking_notifier_call_chain(&dev->bus->p->bus_notifier,
  					     BUS_NOTIFY_BIND_DRIVER, dev);

  	ret = sysfs_create_link(&dev->driver->p->kobj, &dev->kobj,

  			  kobject_name(&dev->kobj));

  	if (ret == 0) {

  		ret = sysfs_create_link(&dev->kobj, &dev->driver->p->kobj,

  					"driver");
  		if (ret)

  			sysfs_remove_link(&dev->driver->p->kobj,

  					kobject_name(&dev->kobj));
  	}
  	return ret;

  }

  static void driver_sysfs_remove(struct device *dev)
  {
  	struct device_driver *drv = dev->driver;
  
  	if (drv) {

  		sysfs_remove_link(&drv->p->kobj, kobject_name(&dev->kobj));

  		sysfs_remove_link(&dev->kobj, "driver");
  	}
  }
  
  /**

   * device_bind_driver - bind a driver to one device.
   * @dev: device.

   *

   * Allow manual attachment of a driver to a device.
   * Caller must have already set @dev->driver.

   *

   * Note that this does not modify the bus reference count
   * nor take the bus's rwsem. Please verify those are accounted
   * for before calling this. (It is ok to call with no other effort
   * from a driver's probe() method.)

   *

   * This function must be called with the device lock held.

   */
  int device_bind_driver(struct device *dev)
  {

  	int ret;
  
  	ret = driver_sysfs_add(dev);
  	if (!ret)
  		driver_bound(dev);

  	else if (dev->bus)
  		blocking_notifier_call_chain(&dev->bus->p->bus_notifier,
  					     BUS_NOTIFY_DRIVER_NOT_BOUND, dev);

  	return ret;

  }

  EXPORT_SYMBOL_GPL(device_bind_driver);

  static atomic_t probe_count = ATOMIC_INIT(0);

  static DECLARE_WAIT_QUEUE_HEAD(probe_waitqueue);

  static int really_probe(struct device *dev, struct device_driver *drv)

  {

  	int ret = -EPROBE_DEFER;

  	int local_trigger_count = atomic_read(&deferred_trigger_count);

  	bool test_remove = IS_ENABLED(CONFIG_DEBUG_TEST_DRIVER_REMOVE) &&
  			   !drv->suppress_bind_attrs;

  	if (defer_all_probes) {
  		/*
  		 * Value of defer_all_probes can be set only by
  		 * device_defer_all_probes_enable() which, in turn, will call
  		 * wait_for_device_probe() right after that to avoid any races.
  		 */
  		dev_dbg(dev, "Driver %s force probe deferral
  ", drv->name);
  		driver_deferred_probe_add(dev);
  		return ret;
  	}

  	atomic_inc(&probe_count);

  	pr_debug("bus: '%s': %s: probing driver %s with device %s
  ",

  		 drv->bus->name, __func__, drv->name, dev_name(dev));

  	WARN_ON(!list_empty(&dev->devres_head));

  re_probe:

  	dev->driver = drv;

  
  	/* If using pinctrl, bind pins now before probing */
  	ret = pinctrl_bind_pins(dev);
  	if (ret)

  		goto pinctrl_bind_failed;

  	if (driver_sysfs_add(dev)) {
  		printk(KERN_ERR "%s: driver_sysfs_add(%s) failed
  ",

  			__func__, dev_name(dev));

  		goto probe_failed;
  	}

  	if (dev->pm_domain && dev->pm_domain->activate) {
  		ret = dev->pm_domain->activate(dev);
  		if (ret)
  			goto probe_failed;
  	}

  	/*
  	 * Ensure devices are listed in devices_kset in correct order
  	 * It's important to move Dev to the end of devices_kset before
  	 * calling .probe, because it could be recursive and parent Dev
  	 * should always go first
  	 */
  	devices_kset_move_last(dev);

  	if (dev->bus->probe) {
  		ret = dev->bus->probe(dev);

  		if (ret)

  			goto probe_failed;

  	} else if (drv->probe) {

  		ret = drv->probe(dev);

  		if (ret)

  			goto probe_failed;

  	}

  	if (test_remove) {
  		test_remove = false;

  		if (dev->bus->remove)

  			dev->bus->remove(dev);
  		else if (drv->remove)
  			drv->remove(dev);
  
  		devres_release_all(dev);
  		driver_sysfs_remove(dev);
  		dev->driver = NULL;
  		dev_set_drvdata(dev, NULL);
  		if (dev->pm_domain && dev->pm_domain->dismiss)
  			dev->pm_domain->dismiss(dev);
  		pm_runtime_reinit(dev);
  
  		goto re_probe;
  	}

  	pinctrl_init_done(dev);

  	if (dev->pm_domain && dev->pm_domain->sync)
  		dev->pm_domain->sync(dev);

  	driver_bound(dev);

  	ret = 1;

  	pr_debug("bus: '%s': %s: bound device %s to driver %s
  ",

  		 drv->bus->name, __func__, dev_name(dev), drv->name);

  	goto done;

  probe_failed:

  	if (dev->bus)
  		blocking_notifier_call_chain(&dev->bus->p->bus_notifier,
  					     BUS_NOTIFY_DRIVER_NOT_BOUND, dev);
  pinctrl_bind_failed:

  	devres_release_all(dev);

  	driver_sysfs_remove(dev);
  	dev->driver = NULL;

  	dev_set_drvdata(dev, NULL);

  	if (dev->pm_domain && dev->pm_domain->dismiss)
  		dev->pm_domain->dismiss(dev);

  	pm_runtime_reinit(dev);

  	switch (ret) {
  	case -EPROBE_DEFER:

  		/* Driver requested deferred probing */

  		dev_dbg(dev, "Driver %s requests probe deferral
  ", drv->name);

  		driver_deferred_probe_add(dev);

  		/* Did a trigger occur while probing? Need to re-trigger if yes */
  		if (local_trigger_count != atomic_read(&deferred_trigger_count))
  			driver_deferred_probe_trigger();

  		break;
  	case -ENODEV:
  	case -ENXIO:
  		pr_debug("%s: probe of %s rejects match %d
  ",
  			 drv->name, dev_name(dev), ret);
  		break;
  	default:

  		/* driver matched but the probe failed */
  		printk(KERN_WARNING
  		       "%s: probe of %s failed with error %d
  ",

  		       drv->name, dev_name(dev), ret);

  	}

  	/*
  	 * Ignore errors returned by ->probe so that the next driver can try
  	 * its luck.
  	 */
  	ret = 0;

  done:

  	atomic_dec(&probe_count);

  	wake_up(&probe_waitqueue);

  	return ret;
  }
  
  /**
   * driver_probe_done
   * Determine if the probe sequence is finished or not.
   *
   * Should somehow figure out how to use a semaphore, not an atomic variable...
   */
  int driver_probe_done(void)
  {

  	pr_debug("%s: probe_count = %d
  ", __func__,

  		 atomic_read(&probe_count));
  	if (atomic_read(&probe_count))
  		return -EBUSY;
  	return 0;
  }
  
  /**

   * wait_for_device_probe
   * Wait for device probing to be completed.

   */

  void wait_for_device_probe(void)

  {

  	/* wait for the deferred probe workqueue to finish */

  	flush_work(&deferred_probe_work);

  	/* wait for the known devices to complete their probing */

  	wait_event(probe_waitqueue, atomic_read(&probe_count) == 0);

  	async_synchronize_full();

  }

  EXPORT_SYMBOL_GPL(wait_for_device_probe);

  
  /**

   * driver_probe_device - attempt to bind device & driver together
   * @drv: driver to bind a device to
   * @dev: device to try to bind to the driver
   *

   * This function returns -ENODEV if the device is not registered,

   * 1 if the device is bound successfully and 0 otherwise.

   *

   * This function must be called with @dev lock held.  When called for a
   * USB interface, @dev->parent lock must be held as well.

   *
   * If the device has a parent, runtime-resume the parent before driver probing.

   */

  int driver_probe_device(struct device_driver *drv, struct device *dev)

  {

  	int ret = 0;

  	if (!device_is_registered(dev))
  		return -ENODEV;

  	pr_debug("bus: '%s': %s: matched device %s with driver %s
  ",

  		 drv->bus->name, __func__, dev_name(dev), drv->name);

  	if (dev->parent)
  		pm_runtime_get_sync(dev->parent);

  	pm_runtime_barrier(dev);

  	ret = really_probe(dev, drv);

  	pm_request_idle(dev);

  	if (dev->parent)
  		pm_runtime_put(dev->parent);

  	return ret;

  }

  bool driver_allows_async_probing(struct device_driver *drv)

  {

  	switch (drv->probe_type) {
  	case PROBE_PREFER_ASYNCHRONOUS:

  		return true;

  	case PROBE_FORCE_SYNCHRONOUS:
  		return false;
  
  	default:

  		if (module_requested_async_probing(drv->owner))

  			return true;

  		return false;
  	}

  }
  
  struct device_attach_data {
  	struct device *dev;
  
  	/*
  	 * Indicates whether we are are considering asynchronous probing or
  	 * not. Only initial binding after device or driver registration
  	 * (including deferral processing) may be done asynchronously, the
  	 * rest is always synchronous, as we expect it is being done by
  	 * request from userspace.
  	 */
  	bool check_async;
  
  	/*
  	 * Indicates if we are binding synchronous or asynchronous drivers.
  	 * When asynchronous probing is enabled we'll execute 2 passes
  	 * over drivers: first pass doing synchronous probing and second
  	 * doing asynchronous probing (if synchronous did not succeed -
  	 * most likely because there was no driver requiring synchronous
  	 * probing - and we found asynchronous driver during first pass).
  	 * The 2 passes are done because we can't shoot asynchronous
  	 * probe for given device and driver from bus_for_each_drv() since
  	 * driver pointer is not guaranteed to stay valid once
  	 * bus_for_each_drv() iterates to the next driver on the bus.
  	 */
  	bool want_async;
  
  	/*
  	 * We'll set have_async to 'true' if, while scanning for matching
  	 * driver, we'll encounter one that requests asynchronous probing.
  	 */
  	bool have_async;
  };
  
  static int __device_attach_driver(struct device_driver *drv, void *_data)
  {
  	struct device_attach_data *data = _data;
  	struct device *dev = data->dev;
  	bool async_allowed;

  	int ret;

  
  	/*
  	 * Check if device has already been claimed. This may
  	 * happen with driver loading, device discovery/registration,
  	 * and deferred probe processing happens all at once with
  	 * multiple threads.
  	 */
  	if (dev->driver)
  		return -EBUSY;

  	ret = driver_match_device(drv, dev);
  	if (ret == 0) {
  		/* no match */

  		return 0;

  	} else if (ret == -EPROBE_DEFER) {
  		dev_dbg(dev, "Device match requests probe deferral
  ");
  		driver_deferred_probe_add(dev);
  	} else if (ret < 0) {
  		dev_dbg(dev, "Bus failed to match device: %d", ret);
  		return ret;
  	} /* ret > 0 means positive match */

  	async_allowed = driver_allows_async_probing(drv);
  
  	if (async_allowed)
  		data->have_async = true;
  
  	if (data->check_async && async_allowed != data->want_async)
  		return 0;

  	return driver_probe_device(drv, dev);

  }

  static void __device_attach_async_helper(void *_dev, async_cookie_t cookie)
  {
  	struct device *dev = _dev;
  	struct device_attach_data data = {
  		.dev		= dev,
  		.check_async	= true,
  		.want_async	= true,
  	};
  
  	device_lock(dev);

  	if (dev->parent)
  		pm_runtime_get_sync(dev->parent);

  	bus_for_each_drv(dev->bus, NULL, &data, __device_attach_driver);
  	dev_dbg(dev, "async probe completed
  ");
  
  	pm_request_idle(dev);

  	if (dev->parent)
  		pm_runtime_put(dev->parent);

  	device_unlock(dev);
  
  	put_device(dev);
  }

  static int __device_attach(struct device *dev, bool allow_async)

  {

  	int ret = 0;

  	device_lock(dev);

  	if (dev->driver) {

  		if (device_is_bound(dev)) {

  			ret = 1;
  			goto out_unlock;
  		}

  		ret = device_bind_driver(dev);
  		if (ret == 0)
  			ret = 1;

  		else {
  			dev->driver = NULL;
  			ret = 0;
  		}

  	} else {

  		struct device_attach_data data = {
  			.dev = dev,
  			.check_async = allow_async,
  			.want_async = false,
  		};

  		if (dev->parent)
  			pm_runtime_get_sync(dev->parent);

  		ret = bus_for_each_drv(dev->bus, NULL, &data,
  					__device_attach_driver);
  		if (!ret && allow_async && data.have_async) {
  			/*
  			 * If we could not find appropriate driver
  			 * synchronously and we are allowed to do
  			 * async probes and there are drivers that
  			 * want to probe asynchronously, we'll
  			 * try them.
  			 */
  			dev_dbg(dev, "scheduling asynchronous probe
  ");
  			get_device(dev);
  			async_schedule(__device_attach_async_helper, dev);
  		} else {
  			pm_request_idle(dev);
  		}

  
  		if (dev->parent)
  			pm_runtime_put(dev->parent);

  	}

  out_unlock:

  	device_unlock(dev);

  	return ret;

  }

  
  /**
   * device_attach - try to attach device to a driver.
   * @dev: device.
   *
   * Walk the list of drivers that the bus has and call
   * driver_probe_device() for each pair. If a compatible
   * pair is found, break out and return.
   *
   * Returns 1 if the device was bound to a driver;
   * 0 if no matching driver was found;
   * -ENODEV if the device is not registered.
   *
   * When called for a USB interface, @dev->parent lock must be held.
   */
  int device_attach(struct device *dev)
  {
  	return __device_attach(dev, false);
  }

  EXPORT_SYMBOL_GPL(device_attach);

  void device_initial_probe(struct device *dev)
  {
  	__device_attach(dev, true);
  }

  static int __driver_attach(struct device *dev, void *data)

  {

  	struct device_driver *drv = data;

  	int ret;

  
  	/*
  	 * Lock device and try to bind to it. We drop the error
  	 * here and always return 0, because we need to keep trying
  	 * to bind to devices and some drivers will return an error
  	 * simply if it didn't support the device.
  	 *
  	 * driver_probe_device() will spit a warning if there
  	 * is an error.
  	 */

  	ret = driver_match_device(drv, dev);
  	if (ret == 0) {
  		/* no match */

  		return 0;

  	} else if (ret == -EPROBE_DEFER) {
  		dev_dbg(dev, "Device match requests probe deferral
  ");
  		driver_deferred_probe_add(dev);
  	} else if (ret < 0) {
  		dev_dbg(dev, "Bus failed to match device: %d", ret);
  		return ret;
  	} /* ret > 0 means positive match */

  	if (dev->parent)	/* Needed for USB */

  		device_lock(dev->parent);
  	device_lock(dev);

  	if (!dev->driver)
  		driver_probe_device(drv, dev);

  	device_unlock(dev);

  	if (dev->parent)

  		device_unlock(dev->parent);

  	return 0;
  }
  
  /**

   * driver_attach - try to bind driver to devices.
   * @drv: driver.

   *

   * Walk the list of devices that the bus has on it and try to
   * match the driver with each one.  If driver_probe_device()
   * returns 0 and the @dev->driver is set, we've found a
   * compatible pair.

   */

  int driver_attach(struct device_driver *drv)

  {

  	return bus_for_each_dev(drv->bus, NULL, drv, __driver_attach);

  }

  EXPORT_SYMBOL_GPL(driver_attach);

  /*

   * __device_release_driver() must be called with @dev lock held.
   * When called for a USB interface, @dev->parent lock must be held as well.

   */

  static void __device_release_driver(struct device *dev)

  {

  	struct device_driver *drv;

  	drv = dev->driver;

  	if (drv) {

  		if (driver_allows_async_probing(drv))
  			async_synchronize_full();

  		pm_runtime_get_sync(dev);

  		driver_sysfs_remove(dev);

  		if (dev->bus)

  			blocking_notifier_call_chain(&dev->bus->p->bus_notifier,

  						     BUS_NOTIFY_UNBIND_DRIVER,
  						     dev);

  		pm_runtime_put_sync(dev);

  		if (dev->bus && dev->bus->remove)

  			dev->bus->remove(dev);
  		else if (drv->remove)

  			drv->remove(dev);

  		devres_release_all(dev);

  		dev->driver = NULL;

  		dev_set_drvdata(dev, NULL);

  		if (dev->pm_domain && dev->pm_domain->dismiss)
  			dev->pm_domain->dismiss(dev);

  		pm_runtime_reinit(dev);

  		klist_remove(&dev->p->knode_driver);

  		device_pm_check_callbacks(dev);

  		if (dev->bus)
  			blocking_notifier_call_chain(&dev->bus->p->bus_notifier,
  						     BUS_NOTIFY_UNBOUND_DRIVER,
  						     dev);

  	}

  }

  /**

   * device_release_driver - manually detach device from driver.
   * @dev: device.

   *

   * Manually detach device from driver.

   * When called for a USB interface, @dev->parent lock must be held.

   */

  void device_release_driver(struct device *dev)

  {

  	/*
  	 * If anyone calls device_release_driver() recursively from
  	 * within their ->remove callback for the same device, they
  	 * will deadlock right here.
  	 */

  	device_lock(dev);

  	__device_release_driver(dev);

  	device_unlock(dev);

  }

  EXPORT_SYMBOL_GPL(device_release_driver);

  /**
   * driver_detach - detach driver from all devices it controls.
   * @drv: driver.
   */

  void driver_detach(struct device_driver *drv)

  {

  	struct device_private *dev_prv;

  	struct device *dev;

  
  	for (;;) {

  		spin_lock(&drv->p->klist_devices.k_lock);
  		if (list_empty(&drv->p->klist_devices.k_list)) {
  			spin_unlock(&drv->p->klist_devices.k_lock);

  			break;
  		}

  		dev_prv = list_entry(drv->p->klist_devices.k_list.prev,
  				     struct device_private,
  				     knode_driver.n_node);
  		dev = dev_prv->device;

  		get_device(dev);

  		spin_unlock(&drv->p->klist_devices.k_lock);

  		if (dev->parent)	/* Needed for USB */

  			device_lock(dev->parent);
  		device_lock(dev);

  		if (dev->driver == drv)
  			__device_release_driver(dev);

  		device_unlock(dev);

  		if (dev->parent)

  			device_unlock(dev->parent);

  		put_device(dev);
  	}

  }