cpuidle: menu: Avoid taking spinlock for accessing QoS values

[linux/fpc-iii.git] / drivers / base / power / qos.c

/*
 * 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;

        lockdep_assert_held(&dev->power.lock);

        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)
{
        lockdep_assert_held(&dev->power.lock);

        return dev_pm_qos_raw_read_value(dev);
}

/**
 * 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_RESUME_LATENCY:
                ret = pm_qos_update_target(&qos->resume_latency,
                                           &req->data.pnode, action, value);
                if (ret) {
                        value = pm_qos_read_value(&qos->resume_latency);
                        blocking_notifier_call_chain(&dev_pm_notifiers,
                                                     (unsigned long)value,
                                                     req);
                }
                break;
        case DEV_PM_QOS_LATENCY_TOLERANCE:
                ret = pm_qos_update_target(&qos->latency_tolerance,
                                           &req->data.pnode, action, value);
                if (ret) {
                        value = pm_qos_read_value(&qos->latency_tolerance);
                        req->dev->power.set_latency_tolerance(req->dev, value);
                }
                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->resume_latency;
        plist_head_init(&c->list);
        c->target_value = PM_QOS_RESUME_LATENCY_DEFAULT_VALUE;
        c->default_value = PM_QOS_RESUME_LATENCY_DEFAULT_VALUE;
        c->no_constraint_value = PM_QOS_RESUME_LATENCY_DEFAULT_VALUE;
        c->type = PM_QOS_MIN;
        c->notifiers = n;

        c = &qos->latency_tolerance;
        plist_head_init(&c->list);
        c->target_value = PM_QOS_LATENCY_TOLERANCE_DEFAULT_VALUE;
        c->default_value = PM_QOS_LATENCY_TOLERANCE_DEFAULT_VALUE;
        c->no_constraint_value = PM_QOS_LATENCY_TOLERANCE_NO_CONSTRAINT;
        c->type = PM_QOS_MIN;

        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_resume_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->resume_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));
        }
        c = &qos->latency_tolerance;
        plist_for_each_entry_safe(req, tmp, &c->list, data.pnode) {
                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);
}

static bool dev_pm_qos_invalid_request(struct device *dev,
                                       struct dev_pm_qos_request *req)
{
        return !req || (req->type == DEV_PM_QOS_LATENCY_TOLERANCE
                        && !dev->power.set_latency_tolerance);
}

static 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 || dev_pm_qos_invalid_request(dev, req))
                return -EINVAL;

        if (WARN(dev_pm_qos_request_active(req),
                 "%s() called for already added request\n", __func__))
                return -EINVAL;

        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);
        }
        return ret;
}

/**
 * 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;

        mutex_lock(&dev_pm_qos_mtx);
        ret = __dev_pm_qos_add_request(dev, req, type, 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\n", __func__))
                return -EINVAL;

        if (IS_ERR_OR_NULL(req->dev->power.qos))
                return -ENODEV;

        switch(req->type) {
        case DEV_PM_QOS_RESUME_LATENCY:
        case DEV_PM_QOS_LATENCY_TOLERANCE:
                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\n", __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->resume_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->resume_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.
 * @type: Type of the request.
 * @value: Constraint latency value.
 */
int dev_pm_qos_add_ancestor_request(struct device *dev,
                                    struct dev_pm_qos_request *req,
                                    enum dev_pm_qos_req_type type, s32 value)
{
        struct device *ancestor = dev->parent;
        int ret = -ENODEV;

        switch (type) {
        case DEV_PM_QOS_RESUME_LATENCY:
                while (ancestor && !ancestor->power.ignore_children)
                        ancestor = ancestor->parent;

                break;
        case DEV_PM_QOS_LATENCY_TOLERANCE:
                while (ancestor && !ancestor->power.set_latency_tolerance)
                        ancestor = ancestor->parent;

                break;
        default:
                ancestor = NULL;
        }
        if (ancestor)
                ret = dev_pm_qos_add_request(ancestor, req, type, value);

        if (ret < 0)
                req->dev = NULL;

        return ret;
}
EXPORT_SYMBOL_GPL(dev_pm_qos_add_ancestor_request);

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_RESUME_LATENCY:
                req = dev->power.qos->resume_latency_req;
                dev->power.qos->resume_latency_req = NULL;
                break;
        case DEV_PM_QOS_LATENCY_TOLERANCE:
                req = dev->power.qos->latency_tolerance_req;
                dev->power.qos->latency_tolerance_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_RESUME_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->resume_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->resume_latency_req = req;

        mutex_unlock(&dev_pm_qos_mtx);

        ret = pm_qos_sysfs_add_resume_latency(dev);
        if (ret)
                dev_pm_qos_drop_user_request(dev, DEV_PM_QOS_RESUME_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->resume_latency_req)
                __dev_pm_qos_drop_user_request(dev, DEV_PM_QOS_RESUME_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_resume_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;
}

/**
 * dev_pm_qos_get_user_latency_tolerance - Get user space latency tolerance.
 * @dev: Device to obtain the user space latency tolerance for.
 */
s32 dev_pm_qos_get_user_latency_tolerance(struct device *dev)
{
        s32 ret;

        mutex_lock(&dev_pm_qos_mtx);
        ret = IS_ERR_OR_NULL(dev->power.qos)
                || !dev->power.qos->latency_tolerance_req ?
                        PM_QOS_LATENCY_TOLERANCE_NO_CONSTRAINT :
                        dev->power.qos->latency_tolerance_req->data.pnode.prio;
        mutex_unlock(&dev_pm_qos_mtx);
        return ret;
}

/**
 * dev_pm_qos_update_user_latency_tolerance - Update user space latency tolerance.
 * @dev: Device to update the user space latency tolerance for.
 * @val: New user space latency tolerance for @dev (negative values disable).
 */
int dev_pm_qos_update_user_latency_tolerance(struct device *dev, s32 val)
{
        int ret;

        mutex_lock(&dev_pm_qos_mtx);

        if (IS_ERR_OR_NULL(dev->power.qos)
            || !dev->power.qos->latency_tolerance_req) {
                struct dev_pm_qos_request *req;

                if (val < 0) {
                        if (val == PM_QOS_LATENCY_TOLERANCE_NO_CONSTRAINT)
                                ret = 0;
                        else
                                ret = -EINVAL;
                        goto out;
                }
                req = kzalloc(sizeof(*req), GFP_KERNEL);
                if (!req) {
                        ret = -ENOMEM;
                        goto out;
                }
                ret = __dev_pm_qos_add_request(dev, req, DEV_PM_QOS_LATENCY_TOLERANCE, val);
                if (ret < 0) {
                        kfree(req);
                        goto out;
                }
                dev->power.qos->latency_tolerance_req = req;
        } else {
                if (val < 0) {
                        __dev_pm_qos_drop_user_request(dev, DEV_PM_QOS_LATENCY_TOLERANCE);
                        ret = 0;
                } else {
                        ret = __dev_pm_qos_update_request(dev->power.qos->latency_tolerance_req, val);
                }
        }

 out:
        mutex_unlock(&dev_pm_qos_mtx);
        return ret;
}
EXPORT_SYMBOL_GPL(dev_pm_qos_update_user_latency_tolerance);

/**
 * dev_pm_qos_expose_latency_tolerance - Expose latency tolerance to userspace
 * @dev: Device whose latency tolerance to expose
 */
int dev_pm_qos_expose_latency_tolerance(struct device *dev)
{
        int ret;

        if (!dev->power.set_latency_tolerance)
                return -EINVAL;

        mutex_lock(&dev_pm_qos_sysfs_mtx);
        ret = pm_qos_sysfs_add_latency_tolerance(dev);
        mutex_unlock(&dev_pm_qos_sysfs_mtx);

        return ret;
}
EXPORT_SYMBOL_GPL(dev_pm_qos_expose_latency_tolerance);

/**
 * dev_pm_qos_hide_latency_tolerance - Hide latency tolerance from userspace
 * @dev: Device whose latency tolerance to hide
 */
void dev_pm_qos_hide_latency_tolerance(struct device *dev)
{
        mutex_lock(&dev_pm_qos_sysfs_mtx);
        pm_qos_sysfs_remove_latency_tolerance(dev);
        mutex_unlock(&dev_pm_qos_sysfs_mtx);

        /* Remove the request from user space now */
        pm_runtime_get_sync(dev);
        dev_pm_qos_update_user_latency_tolerance(dev,
                PM_QOS_LATENCY_TOLERANCE_NO_CONSTRAINT);
        pm_runtime_put(dev);
}
EXPORT_SYMBOL_GPL(dev_pm_qos_hide_latency_tolerance);