/*
   * Devices PM QoS constraints management
   *
   * Copyright (C) 2011 Texas Instruments, Inc.
   *
   * 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 module exposes the interface to kernel space for specifying
   * per-device PM QoS dependencies. It provides infrastructure for registration
   * of:
   *
   * Dependents on a QoS value : register requests
   * Watchers of QoS value : get notified when target QoS value changes
   *
   * This QoS design is best effort based. Dependents register their QoS needs.
   * Watchers register to keep track of the current QoS needs of the system.
   * Watchers can register different types of notification callbacks:
   *  . a per-device notification callback using the dev_pm_qos_*_notifier API.
   *    The notification chain data is stored in the per-device constraint
   *    data struct.
   *  . a system-wide notification callback using the dev_pm_qos_*_global_notifier
   *    API. The notification chain data is stored in a static variable.
   *
   * Note about the per-device constraint data struct allocation:
   * . The per-device constraints data struct ptr is tored into the device
   *    dev_pm_info.
   * . To minimize the data usage by the per-device constraints, the data struct
   *   is only allocated at the first call to dev_pm_qos_add_request.
   * . The data is later free'd when the device is removed from the system.
   *  . A global mutex protects the constraints users from the data being
   *     allocated and free'd.
   */
  
  #include <linux/pm_qos.h>
  #include <linux/spinlock.h>
  #include <linux/slab.h>
  #include <linux/device.h>
  #include <linux/mutex.h>
  #include <linux/export.h>
  #include <linux/pm_runtime.h>
  #include <linux/err.h>
  #include <trace/events/power.h>
  
  #include "power.h"
  
  static DEFINE_MUTEX(dev_pm_qos_mtx);
  static DEFINE_MUTEX(dev_pm_qos_sysfs_mtx);
  
  static BLOCKING_NOTIFIER_HEAD(dev_pm_notifiers);
  
  /**
   * __dev_pm_qos_flags - Check PM QoS flags for a given device.
   * @dev: Device to check the PM QoS flags for.
   * @mask: Flags to check against.
   *
   * This routine must be called with dev->power.lock held.
   */
  enum pm_qos_flags_status __dev_pm_qos_flags(struct device *dev, s32 mask)
  {
  	struct dev_pm_qos *qos = dev->power.qos;
  	struct pm_qos_flags *pqf;
  	s32 val;
  
  	if (IS_ERR_OR_NULL(qos))
  		return PM_QOS_FLAGS_UNDEFINED;
  
  	pqf = &qos->flags;
  	if (list_empty(&pqf->list))
  		return PM_QOS_FLAGS_UNDEFINED;
  
  	val = pqf->effective_flags & mask;
  	if (val)
  		return (val == mask) ? PM_QOS_FLAGS_ALL : PM_QOS_FLAGS_SOME;
  
  	return PM_QOS_FLAGS_NONE;
  }
  
  /**
   * dev_pm_qos_flags - Check PM QoS flags for a given device (locked).
   * @dev: Device to check the PM QoS flags for.
   * @mask: Flags to check against.
   */
  enum pm_qos_flags_status dev_pm_qos_flags(struct device *dev, s32 mask)
  {
  	unsigned long irqflags;
  	enum pm_qos_flags_status ret;
  
  	spin_lock_irqsave(&dev->power.lock, irqflags);
  	ret = __dev_pm_qos_flags(dev, mask);
  	spin_unlock_irqrestore(&dev->power.lock, irqflags);
  
  	return ret;
  }
  EXPORT_SYMBOL_GPL(dev_pm_qos_flags);
  
  /**
   * __dev_pm_qos_read_value - Get PM QoS constraint for a given device.
   * @dev: Device to get the PM QoS constraint value for.
   *
   * This routine must be called with dev->power.lock held.
   */
  s32 __dev_pm_qos_read_value(struct device *dev)
  {
  	return IS_ERR_OR_NULL(dev->power.qos) ?
  		0 : pm_qos_read_value(&dev->power.qos->latency);
  }
  
  /**
   * dev_pm_qos_read_value - Get PM QoS constraint for a given device (locked).
   * @dev: Device to get the PM QoS constraint value for.
   */
  s32 dev_pm_qos_read_value(struct device *dev)
  {
  	unsigned long flags;
  	s32 ret;
  
  	spin_lock_irqsave(&dev->power.lock, flags);
  	ret = __dev_pm_qos_read_value(dev);
  	spin_unlock_irqrestore(&dev->power.lock, flags);
  
  	return ret;
  }
  
  /**
   * apply_constraint - Add/modify/remove device PM QoS request.
   * @req: Constraint request to apply
   * @action: Action to perform (add/update/remove).
   * @value: Value to assign to the QoS request.
   *
   * Internal function to update the constraints list using the PM QoS core
   * code and if needed call the per-device and the global notification
   * callbacks
   */
  static int apply_constraint(struct dev_pm_qos_request *req,
  			    enum pm_qos_req_action action, s32 value)
  {
  	struct dev_pm_qos *qos = req->dev->power.qos;
  	int ret;
  
  	switch(req->type) {
  	case DEV_PM_QOS_LATENCY:
  		ret = pm_qos_update_target(&qos->latency, &req->data.pnode,
  					   action, value);
  		if (ret) {
  			value = pm_qos_read_value(&qos->latency);
  			blocking_notifier_call_chain(&dev_pm_notifiers,
  						     (unsigned long)value,
  						     req);
  		}
  		break;
  	case DEV_PM_QOS_FLAGS:
  		ret = pm_qos_update_flags(&qos->flags, &req->data.flr,
  					  action, value);
  		break;
  	default:
  		ret = -EINVAL;
  	}
  
  	return ret;
  }
  
  /*
   * dev_pm_qos_constraints_allocate
   * @dev: device to allocate data for
   *
   * Called at the first call to add_request, for constraint data allocation
   * Must be called with the dev_pm_qos_mtx mutex held
   */
  static int dev_pm_qos_constraints_allocate(struct device *dev)
  {
  	struct dev_pm_qos *qos;
  	struct pm_qos_constraints *c;
  	struct blocking_notifier_head *n;
  
  	qos = kzalloc(sizeof(*qos), GFP_KERNEL);
  	if (!qos)
  		return -ENOMEM;
  
  	n = kzalloc(sizeof(*n), GFP_KERNEL);
  	if (!n) {
  		kfree(qos);
  		return -ENOMEM;
  	}
  	BLOCKING_INIT_NOTIFIER_HEAD(n);
  
  	c = &qos->latency;
  	plist_head_init(&c->list);
  	c->target_value = PM_QOS_DEV_LAT_DEFAULT_VALUE;
  	c->default_value = PM_QOS_DEV_LAT_DEFAULT_VALUE;
  	c->type = PM_QOS_MIN;
  	c->notifiers = n;
  
  	INIT_LIST_HEAD(&qos->flags.list);
  
  	spin_lock_irq(&dev->power.lock);
  	dev->power.qos = qos;
  	spin_unlock_irq(&dev->power.lock);
  
  	return 0;
  }
  
  static void __dev_pm_qos_hide_latency_limit(struct device *dev);
  static void __dev_pm_qos_hide_flags(struct device *dev);
  
  /**
   * dev_pm_qos_constraints_destroy
   * @dev: target device
   *
   * Called from the device PM subsystem on device removal under device_pm_lock().
   */
  void dev_pm_qos_constraints_destroy(struct device *dev)
  {
  	struct dev_pm_qos *qos;
  	struct dev_pm_qos_request *req, *tmp;
  	struct pm_qos_constraints *c;
  	struct pm_qos_flags *f;
  
  	mutex_lock(&dev_pm_qos_sysfs_mtx);
  
  	/*
  	 * If the device's PM QoS resume latency limit or PM QoS flags have been
  	 * exposed to user space, they have to be hidden at this point.
  	 */
  	pm_qos_sysfs_remove_latency(dev);
  	pm_qos_sysfs_remove_flags(dev);
  
  	mutex_lock(&dev_pm_qos_mtx);
  
  	__dev_pm_qos_hide_latency_limit(dev);
  	__dev_pm_qos_hide_flags(dev);
  
  	qos = dev->power.qos;
  	if (!qos)
  		goto out;
  
  	/* Flush the constraints lists for the device. */
  	c = &qos->latency;
  	plist_for_each_entry_safe(req, tmp, &c->list, data.pnode) {
  		/*
  		 * Update constraints list and call the notification
  		 * callbacks if needed
  		 */
  		apply_constraint(req, PM_QOS_REMOVE_REQ, PM_QOS_DEFAULT_VALUE);
  		memset(req, 0, sizeof(*req));
  	}
  	f = &qos->flags;
  	list_for_each_entry_safe(req, tmp, &f->list, data.flr.node) {
  		apply_constraint(req, PM_QOS_REMOVE_REQ, PM_QOS_DEFAULT_VALUE);
  		memset(req, 0, sizeof(*req));
  	}
  
  	spin_lock_irq(&dev->power.lock);
  	dev->power.qos = ERR_PTR(-ENODEV);
  	spin_unlock_irq(&dev->power.lock);
  
  	kfree(c->notifiers);
  	kfree(qos);
  
   out:
  	mutex_unlock(&dev_pm_qos_mtx);
  
  	mutex_unlock(&dev_pm_qos_sysfs_mtx);
  }
  
  /**
   * dev_pm_qos_add_request - inserts new qos request into the list
   * @dev: target device for the constraint
   * @req: pointer to a preallocated handle
   * @type: type of the request
   * @value: defines the qos request
   *
   * This function inserts a new entry in the device constraints list of
   * requested qos performance characteristics. It recomputes the aggregate
   * QoS expectations of parameters and initializes the dev_pm_qos_request
   * handle.  Caller needs to save this handle for later use in updates and
   * removal.
   *
   * Returns 1 if the aggregated constraint value has changed,
   * 0 if the aggregated constraint value has not changed,
   * -EINVAL in case of wrong parameters, -ENOMEM if there's not enough memory
   * to allocate for data structures, -ENODEV if the device has just been removed
   * from the system.
   *
   * Callers should ensure that the target device is not RPM_SUSPENDED before
   * using this function for requests of type DEV_PM_QOS_FLAGS.
   */
  int dev_pm_qos_add_request(struct device *dev, struct dev_pm_qos_request *req,
  			   enum dev_pm_qos_req_type type, s32 value)
  {
  	int ret = 0;
  
  	if (!dev || !req) /*guard against callers passing in null */
  		return -EINVAL;
  
  	if (WARN(dev_pm_qos_request_active(req),
  		 "%s() called for already added request
  ", __func__))
  		return -EINVAL;
  
  	mutex_lock(&dev_pm_qos_mtx);
  
  	if (IS_ERR(dev->power.qos))
  		ret = -ENODEV;
  	else if (!dev->power.qos)
  		ret = dev_pm_qos_constraints_allocate(dev);
  
  	trace_dev_pm_qos_add_request(dev_name(dev), type, value);
  	if (!ret) {
  		req->dev = dev;
  		req->type = type;
  		ret = apply_constraint(req, PM_QOS_ADD_REQ, value);
  	}
  
  	mutex_unlock(&dev_pm_qos_mtx);
  
  	return ret;
  }
  EXPORT_SYMBOL_GPL(dev_pm_qos_add_request);
  
  /**
   * __dev_pm_qos_update_request - Modify an existing device PM QoS request.
   * @req : PM QoS request to modify.
   * @new_value: New value to request.
   */
  static int __dev_pm_qos_update_request(struct dev_pm_qos_request *req,
  				       s32 new_value)
  {
  	s32 curr_value;
  	int ret = 0;
  
  	if (!req) /*guard against callers passing in null */
  		return -EINVAL;
  
  	if (WARN(!dev_pm_qos_request_active(req),
  		 "%s() called for unknown object
  ", __func__))
  		return -EINVAL;
  
  	if (IS_ERR_OR_NULL(req->dev->power.qos))
  		return -ENODEV;
  
  	switch(req->type) {
  	case DEV_PM_QOS_LATENCY:
  		curr_value = req->data.pnode.prio;
  		break;
  	case DEV_PM_QOS_FLAGS:
  		curr_value = req->data.flr.flags;
  		break;
  	default:
  		return -EINVAL;
  	}
  
  	trace_dev_pm_qos_update_request(dev_name(req->dev), req->type,
  					new_value);
  	if (curr_value != new_value)
  		ret = apply_constraint(req, PM_QOS_UPDATE_REQ, new_value);
  
  	return ret;
  }
  
  /**
   * dev_pm_qos_update_request - modifies an existing qos request
   * @req : handle to list element holding a dev_pm_qos request to use
   * @new_value: defines the qos request
   *
   * Updates an existing dev PM qos request along with updating the
   * target value.
   *
   * Attempts are made to make this code callable on hot code paths.
   *
   * Returns 1 if the aggregated constraint value has changed,
   * 0 if the aggregated constraint value has not changed,
   * -EINVAL in case of wrong parameters, -ENODEV if the device has been
   * removed from the system
   *
   * Callers should ensure that the target device is not RPM_SUSPENDED before
   * using this function for requests of type DEV_PM_QOS_FLAGS.
   */
  int dev_pm_qos_update_request(struct dev_pm_qos_request *req, s32 new_value)
  {
  	int ret;
  
  	mutex_lock(&dev_pm_qos_mtx);
  	ret = __dev_pm_qos_update_request(req, new_value);
  	mutex_unlock(&dev_pm_qos_mtx);
  	return ret;
  }
  EXPORT_SYMBOL_GPL(dev_pm_qos_update_request);
  
  static int __dev_pm_qos_remove_request(struct dev_pm_qos_request *req)
  {
  	int ret;
  
  	if (!req) /*guard against callers passing in null */
  		return -EINVAL;
  
  	if (WARN(!dev_pm_qos_request_active(req),
  		 "%s() called for unknown object
  ", __func__))
  		return -EINVAL;
  
  	if (IS_ERR_OR_NULL(req->dev->power.qos))
  		return -ENODEV;
  
  	trace_dev_pm_qos_remove_request(dev_name(req->dev), req->type,
  					PM_QOS_DEFAULT_VALUE);
  	ret = apply_constraint(req, PM_QOS_REMOVE_REQ, PM_QOS_DEFAULT_VALUE);
  	memset(req, 0, sizeof(*req));
  	return ret;
  }
  
  /**
   * dev_pm_qos_remove_request - modifies an existing qos request
   * @req: handle to request list element
   *
   * Will remove pm qos request from the list of constraints and
   * recompute the current target value. Call this on slow code paths.
   *
   * Returns 1 if the aggregated constraint value has changed,
   * 0 if the aggregated constraint value has not changed,
   * -EINVAL in case of wrong parameters, -ENODEV if the device has been
   * removed from the system
   *
   * Callers should ensure that the target device is not RPM_SUSPENDED before
   * using this function for requests of type DEV_PM_QOS_FLAGS.
   */
  int dev_pm_qos_remove_request(struct dev_pm_qos_request *req)
  {
  	int ret;
  
  	mutex_lock(&dev_pm_qos_mtx);
  	ret = __dev_pm_qos_remove_request(req);
  	mutex_unlock(&dev_pm_qos_mtx);
  	return ret;
  }
  EXPORT_SYMBOL_GPL(dev_pm_qos_remove_request);
  
  /**
   * dev_pm_qos_add_notifier - sets notification entry for changes to target value
   * of per-device PM QoS constraints
   *
   * @dev: target device for the constraint
   * @notifier: notifier block managed by caller.
   *
   * Will register the notifier into a notification chain that gets called
   * upon changes to the target value for the device.
   *
   * If the device's constraints object doesn't exist when this routine is called,
   * it will be created (or error code will be returned if that fails).
   */
  int dev_pm_qos_add_notifier(struct device *dev, struct notifier_block *notifier)
  {
  	int ret = 0;
  
  	mutex_lock(&dev_pm_qos_mtx);
  
  	if (IS_ERR(dev->power.qos))
  		ret = -ENODEV;
  	else if (!dev->power.qos)
  		ret = dev_pm_qos_constraints_allocate(dev);
  
  	if (!ret)
  		ret = blocking_notifier_chain_register(
  				dev->power.qos->latency.notifiers, notifier);
  
  	mutex_unlock(&dev_pm_qos_mtx);
  	return ret;
  }
  EXPORT_SYMBOL_GPL(dev_pm_qos_add_notifier);
  
  /**
   * dev_pm_qos_remove_notifier - deletes notification for changes to target value
   * of per-device PM QoS constraints
   *
   * @dev: target device for the constraint
   * @notifier: notifier block to be removed.
   *
   * Will remove the notifier from the notification chain that gets called
   * upon changes to the target value.
   */
  int dev_pm_qos_remove_notifier(struct device *dev,
  			       struct notifier_block *notifier)
  {
  	int retval = 0;
  
  	mutex_lock(&dev_pm_qos_mtx);
  
  	/* Silently return if the constraints object is not present. */
  	if (!IS_ERR_OR_NULL(dev->power.qos))
  		retval = blocking_notifier_chain_unregister(
  				dev->power.qos->latency.notifiers,
  				notifier);
  
  	mutex_unlock(&dev_pm_qos_mtx);
  	return retval;
  }
  EXPORT_SYMBOL_GPL(dev_pm_qos_remove_notifier);
  
  /**
   * dev_pm_qos_add_global_notifier - sets notification entry for changes to
   * target value of the PM QoS constraints for any device
   *
   * @notifier: notifier block managed by caller.
   *
   * Will register the notifier into a notification chain that gets called
   * upon changes to the target value for any device.
   */
  int dev_pm_qos_add_global_notifier(struct notifier_block *notifier)
  {
  	return blocking_notifier_chain_register(&dev_pm_notifiers, notifier);
  }
  EXPORT_SYMBOL_GPL(dev_pm_qos_add_global_notifier);
  
  /**
   * dev_pm_qos_remove_global_notifier - deletes notification for changes to
   * target value of PM QoS constraints for any device
   *
   * @notifier: notifier block to be removed.
   *
   * Will remove the notifier from the notification chain that gets called
   * upon changes to the target value for any device.
   */
  int dev_pm_qos_remove_global_notifier(struct notifier_block *notifier)
  {
  	return blocking_notifier_chain_unregister(&dev_pm_notifiers, notifier);
  }
  EXPORT_SYMBOL_GPL(dev_pm_qos_remove_global_notifier);
  
  /**
   * dev_pm_qos_add_ancestor_request - Add PM QoS request for device's ancestor.
   * @dev: Device whose ancestor to add the request for.
   * @req: Pointer to the preallocated handle.
   * @value: Constraint latency value.
   */
  int dev_pm_qos_add_ancestor_request(struct device *dev,
  				    struct dev_pm_qos_request *req, s32 value)
  {
  	struct device *ancestor = dev->parent;
  	int ret = -ENODEV;
  
  	while (ancestor && !ancestor->power.ignore_children)
  		ancestor = ancestor->parent;
  
  	if (ancestor)
  		ret = dev_pm_qos_add_request(ancestor, req,
  					     DEV_PM_QOS_LATENCY, value);
  
  	if (ret < 0)
  		req->dev = NULL;
  
  	return ret;
  }
  EXPORT_SYMBOL_GPL(dev_pm_qos_add_ancestor_request);
  
  #ifdef CONFIG_PM_RUNTIME
  static void __dev_pm_qos_drop_user_request(struct device *dev,
  					   enum dev_pm_qos_req_type type)
  {
  	struct dev_pm_qos_request *req = NULL;
  
  	switch(type) {
  	case DEV_PM_QOS_LATENCY:
  		req = dev->power.qos->latency_req;
  		dev->power.qos->latency_req = NULL;
  		break;
  	case DEV_PM_QOS_FLAGS:
  		req = dev->power.qos->flags_req;
  		dev->power.qos->flags_req = NULL;
  		break;
  	}
  	__dev_pm_qos_remove_request(req);
  	kfree(req);
  }
  
  static void dev_pm_qos_drop_user_request(struct device *dev,
  					 enum dev_pm_qos_req_type type)
  {
  	mutex_lock(&dev_pm_qos_mtx);
  	__dev_pm_qos_drop_user_request(dev, type);
  	mutex_unlock(&dev_pm_qos_mtx);
  }
  
  /**
   * dev_pm_qos_expose_latency_limit - Expose PM QoS latency limit to user space.
   * @dev: Device whose PM QoS latency limit is to be exposed to user space.
   * @value: Initial value of the latency limit.
   */
  int dev_pm_qos_expose_latency_limit(struct device *dev, s32 value)
  {
  	struct dev_pm_qos_request *req;
  	int ret;
  
  	if (!device_is_registered(dev) || value < 0)
  		return -EINVAL;
  
  	req = kzalloc(sizeof(*req), GFP_KERNEL);
  	if (!req)
  		return -ENOMEM;
  
  	ret = dev_pm_qos_add_request(dev, req, DEV_PM_QOS_LATENCY, value);
  	if (ret < 0) {
  		kfree(req);
  		return ret;
  	}
  
  	mutex_lock(&dev_pm_qos_sysfs_mtx);
  
  	mutex_lock(&dev_pm_qos_mtx);
  
  	if (IS_ERR_OR_NULL(dev->power.qos))
  		ret = -ENODEV;
  	else if (dev->power.qos->latency_req)
  		ret = -EEXIST;
  
  	if (ret < 0) {
  		__dev_pm_qos_remove_request(req);
  		kfree(req);
  		mutex_unlock(&dev_pm_qos_mtx);
  		goto out;
  	}
  	dev->power.qos->latency_req = req;
  
  	mutex_unlock(&dev_pm_qos_mtx);
  
  	ret = pm_qos_sysfs_add_latency(dev);
  	if (ret)
  		dev_pm_qos_drop_user_request(dev, DEV_PM_QOS_LATENCY);
  
   out:
  	mutex_unlock(&dev_pm_qos_sysfs_mtx);
  	return ret;
  }
  EXPORT_SYMBOL_GPL(dev_pm_qos_expose_latency_limit);
  
  static void __dev_pm_qos_hide_latency_limit(struct device *dev)
  {
  	if (!IS_ERR_OR_NULL(dev->power.qos) && dev->power.qos->latency_req)
  		__dev_pm_qos_drop_user_request(dev, DEV_PM_QOS_LATENCY);
  }
  
  /**
   * dev_pm_qos_hide_latency_limit - Hide PM QoS latency limit from user space.
   * @dev: Device whose PM QoS latency limit is to be hidden from user space.
   */
  void dev_pm_qos_hide_latency_limit(struct device *dev)
  {
  	mutex_lock(&dev_pm_qos_sysfs_mtx);
  
  	pm_qos_sysfs_remove_latency(dev);
  
  	mutex_lock(&dev_pm_qos_mtx);
  	__dev_pm_qos_hide_latency_limit(dev);
  	mutex_unlock(&dev_pm_qos_mtx);
  
  	mutex_unlock(&dev_pm_qos_sysfs_mtx);
  }
  EXPORT_SYMBOL_GPL(dev_pm_qos_hide_latency_limit);
  
  /**
   * dev_pm_qos_expose_flags - Expose PM QoS flags of a device to user space.
   * @dev: Device whose PM QoS flags are to be exposed to user space.
   * @val: Initial values of the flags.
   */
  int dev_pm_qos_expose_flags(struct device *dev, s32 val)
  {
  	struct dev_pm_qos_request *req;
  	int ret;
  
  	if (!device_is_registered(dev))
  		return -EINVAL;
  
  	req = kzalloc(sizeof(*req), GFP_KERNEL);
  	if (!req)
  		return -ENOMEM;
  
  	ret = dev_pm_qos_add_request(dev, req, DEV_PM_QOS_FLAGS, val);
  	if (ret < 0) {
  		kfree(req);
  		return ret;
  	}
  
  	pm_runtime_get_sync(dev);
  	mutex_lock(&dev_pm_qos_sysfs_mtx);
  
  	mutex_lock(&dev_pm_qos_mtx);
  
  	if (IS_ERR_OR_NULL(dev->power.qos))
  		ret = -ENODEV;
  	else if (dev->power.qos->flags_req)
  		ret = -EEXIST;
  
  	if (ret < 0) {
  		__dev_pm_qos_remove_request(req);
  		kfree(req);
  		mutex_unlock(&dev_pm_qos_mtx);
  		goto out;
  	}
  	dev->power.qos->flags_req = req;
  
  	mutex_unlock(&dev_pm_qos_mtx);
  
  	ret = pm_qos_sysfs_add_flags(dev);
  	if (ret)
  		dev_pm_qos_drop_user_request(dev, DEV_PM_QOS_FLAGS);
  
   out:
  	mutex_unlock(&dev_pm_qos_sysfs_mtx);
  	pm_runtime_put(dev);
  	return ret;
  }
  EXPORT_SYMBOL_GPL(dev_pm_qos_expose_flags);
  
  static void __dev_pm_qos_hide_flags(struct device *dev)
  {
  	if (!IS_ERR_OR_NULL(dev->power.qos) && dev->power.qos->flags_req)
  		__dev_pm_qos_drop_user_request(dev, DEV_PM_QOS_FLAGS);
  }
  
  /**
   * dev_pm_qos_hide_flags - Hide PM QoS flags of a device from user space.
   * @dev: Device whose PM QoS flags are to be hidden from user space.
   */
  void dev_pm_qos_hide_flags(struct device *dev)
  {
  	pm_runtime_get_sync(dev);
  	mutex_lock(&dev_pm_qos_sysfs_mtx);
  
  	pm_qos_sysfs_remove_flags(dev);
  
  	mutex_lock(&dev_pm_qos_mtx);
  	__dev_pm_qos_hide_flags(dev);
  	mutex_unlock(&dev_pm_qos_mtx);
  
  	mutex_unlock(&dev_pm_qos_sysfs_mtx);
  	pm_runtime_put(dev);
  }
  EXPORT_SYMBOL_GPL(dev_pm_qos_hide_flags);
  
  /**
   * dev_pm_qos_update_flags - Update PM QoS flags request owned by user space.
   * @dev: Device to update the PM QoS flags request for.
   * @mask: Flags to set/clear.
   * @set: Whether to set or clear the flags (true means set).
   */
  int dev_pm_qos_update_flags(struct device *dev, s32 mask, bool set)
  {
  	s32 value;
  	int ret;
  
  	pm_runtime_get_sync(dev);
  	mutex_lock(&dev_pm_qos_mtx);
  
  	if (IS_ERR_OR_NULL(dev->power.qos) || !dev->power.qos->flags_req) {
  		ret = -EINVAL;
  		goto out;
  	}
  
  	value = dev_pm_qos_requested_flags(dev);
  	if (set)
  		value |= mask;
  	else
  		value &= ~mask;
  
  	ret = __dev_pm_qos_update_request(dev->power.qos->flags_req, value);
  
   out:
  	mutex_unlock(&dev_pm_qos_mtx);
  	pm_runtime_put(dev);
  	return ret;
  }
  #else /* !CONFIG_PM_RUNTIME */
  static void __dev_pm_qos_hide_latency_limit(struct device *dev) {}
  static void __dev_pm_qos_hide_flags(struct device *dev) {}
  #endif /* CONFIG_PM_RUNTIME */