tree-wide: fix comment/printk typos

[mirror_ubuntu-artful-kernel.git] / drivers / base / power / main.c

/*
 * drivers/base/power/main.c - Where the driver meets power management.
 *
 * Copyright (c) 2003 Patrick Mochel
 * Copyright (c) 2003 Open Source Development Lab
 *
 * This file is released under the GPLv2
 *
 *
 * The driver model core calls device_pm_add() when a device is registered.
 * This will initialize the embedded device_pm_info object in the device
 * and add it to the list of power-controlled devices. sysfs entries for
 * controlling device power management will also be added.
 *
 * A separate list is used for keeping track of power info, because the power
 * domain dependencies may differ from the ancestral dependencies that the
 * subsystem list maintains.
 */

#include <linux/device.h>
#include <linux/kallsyms.h>
#include <linux/mutex.h>
#include <linux/pm.h>
#include <linux/pm_runtime.h>
#include <linux/resume-trace.h>
#include <linux/interrupt.h>
#include <linux/sched.h>
#include <linux/async.h>

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

/*
 * The entries in the dpm_list list are in a depth first order, simply
 * because children are guaranteed to be discovered after parents, and
 * are inserted at the back of the list on discovery.
 *
 * Since device_pm_add() may be called with a device lock held,
 * we must never try to acquire a device lock while holding
 * dpm_list_mutex.
 */

LIST_HEAD(dpm_list);

static DEFINE_MUTEX(dpm_list_mtx);
static pm_message_t pm_transition;

/*
 * Set once the preparation of devices for a PM transition has started, reset
 * before starting to resume devices.  Protected by dpm_list_mtx.
 */
static bool transition_started;

static int async_error;

/**
 * device_pm_init - Initialize the PM-related part of a device object.
 * @dev: Device object being initialized.
 */
void device_pm_init(struct device *dev)
{
        dev->power.status = DPM_ON;
        init_completion(&dev->power.completion);
        complete_all(&dev->power.completion);
        dev->power.wakeup = NULL;
        spin_lock_init(&dev->power.lock);
        pm_runtime_init(dev);
}

/**
 * device_pm_lock - Lock the list of active devices used by the PM core.
 */
void device_pm_lock(void)
{
        mutex_lock(&dpm_list_mtx);
}

/**
 * device_pm_unlock - Unlock the list of active devices used by the PM core.
 */
void device_pm_unlock(void)
{
        mutex_unlock(&dpm_list_mtx);
}

/**
 * device_pm_add - Add a device to the PM core's list of active devices.
 * @dev: Device to add to the list.
 */
void device_pm_add(struct device *dev)
{
        pr_debug("PM: Adding info for %s:%s\n",
                 dev->bus ? dev->bus->name : "No Bus",
                 kobject_name(&dev->kobj));
        mutex_lock(&dpm_list_mtx);
        if (dev->parent) {
                if (dev->parent->power.status >= DPM_SUSPENDING)
                        dev_warn(dev, "parent %s should not be sleeping\n",
                                 dev_name(dev->parent));
        } else if (transition_started) {
                /*
                 * We refuse to register parentless devices while a PM
                 * transition is in progress in order to avoid leaving them
                 * unhandled down the road
                 */
                dev_WARN(dev, "Parentless device registered during a PM transaction\n");
        }

        list_add_tail(&dev->power.entry, &dpm_list);
        mutex_unlock(&dpm_list_mtx);
}

/**
 * device_pm_remove - Remove a device from the PM core's list of active devices.
 * @dev: Device to be removed from the list.
 */
void device_pm_remove(struct device *dev)
{
        pr_debug("PM: Removing info for %s:%s\n",
                 dev->bus ? dev->bus->name : "No Bus",
                 kobject_name(&dev->kobj));
        complete_all(&dev->power.completion);
        mutex_lock(&dpm_list_mtx);
        list_del_init(&dev->power.entry);
        mutex_unlock(&dpm_list_mtx);
        device_wakeup_disable(dev);
        pm_runtime_remove(dev);
}

/**
 * device_pm_move_before - Move device in the PM core's list of active devices.
 * @deva: Device to move in dpm_list.
 * @devb: Device @deva should come before.
 */
void device_pm_move_before(struct device *deva, struct device *devb)
{
        pr_debug("PM: Moving %s:%s before %s:%s\n",
                 deva->bus ? deva->bus->name : "No Bus",
                 kobject_name(&deva->kobj),
                 devb->bus ? devb->bus->name : "No Bus",
                 kobject_name(&devb->kobj));
        /* Delete deva from dpm_list and reinsert before devb. */
        list_move_tail(&deva->power.entry, &devb->power.entry);
}

/**
 * device_pm_move_after - Move device in the PM core's list of active devices.
 * @deva: Device to move in dpm_list.
 * @devb: Device @deva should come after.
 */
void device_pm_move_after(struct device *deva, struct device *devb)
{
        pr_debug("PM: Moving %s:%s after %s:%s\n",
                 deva->bus ? deva->bus->name : "No Bus",
                 kobject_name(&deva->kobj),
                 devb->bus ? devb->bus->name : "No Bus",
                 kobject_name(&devb->kobj));
        /* Delete deva from dpm_list and reinsert after devb. */
        list_move(&deva->power.entry, &devb->power.entry);
}

/**
 * device_pm_move_last - Move device to end of the PM core's list of devices.
 * @dev: Device to move in dpm_list.
 */
void device_pm_move_last(struct device *dev)
{
        pr_debug("PM: Moving %s:%s to end of list\n",
                 dev->bus ? dev->bus->name : "No Bus",
                 kobject_name(&dev->kobj));
        list_move_tail(&dev->power.entry, &dpm_list);
}

static ktime_t initcall_debug_start(struct device *dev)
{
        ktime_t calltime = ktime_set(0, 0);

        if (initcall_debug) {
                pr_info("calling  %s+ @ %i\n",
                                dev_name(dev), task_pid_nr(current));
                calltime = ktime_get();
        }

        return calltime;
}

static void initcall_debug_report(struct device *dev, ktime_t calltime,
                                  int error)
{
        ktime_t delta, rettime;

        if (initcall_debug) {
                rettime = ktime_get();
                delta = ktime_sub(rettime, calltime);
                pr_info("call %s+ returned %d after %Ld usecs\n", dev_name(dev),
                        error, (unsigned long long)ktime_to_ns(delta) >> 10);
        }
}

/**
 * dpm_wait - Wait for a PM operation to complete.
 * @dev: Device to wait for.
 * @async: If unset, wait only if the device's power.async_suspend flag is set.
 */
static void dpm_wait(struct device *dev, bool async)
{
        if (!dev)
                return;

        if (async || (pm_async_enabled && dev->power.async_suspend))
                wait_for_completion(&dev->power.completion);
}

static int dpm_wait_fn(struct device *dev, void *async_ptr)
{
        dpm_wait(dev, *((bool *)async_ptr));
        return 0;
}

static void dpm_wait_for_children(struct device *dev, bool async)
{
       device_for_each_child(dev, &async, dpm_wait_fn);
}

/**
 * pm_op - Execute the PM operation appropriate for given PM event.
 * @dev: Device to handle.
 * @ops: PM operations to choose from.
 * @state: PM transition of the system being carried out.
 */
static int pm_op(struct device *dev,
                 const struct dev_pm_ops *ops,
                 pm_message_t state)
{
        int error = 0;
        ktime_t calltime;

        calltime = initcall_debug_start(dev);

        switch (state.event) {
#ifdef CONFIG_SUSPEND
        case PM_EVENT_SUSPEND:
                if (ops->suspend) {
                        error = ops->suspend(dev);
                        suspend_report_result(ops->suspend, error);
                }
                break;
        case PM_EVENT_RESUME:
                if (ops->resume) {
                        error = ops->resume(dev);
                        suspend_report_result(ops->resume, error);
                }
                break;
#endif /* CONFIG_SUSPEND */
#ifdef CONFIG_HIBERNATION
        case PM_EVENT_FREEZE:
        case PM_EVENT_QUIESCE:
                if (ops->freeze) {
                        error = ops->freeze(dev);
                        suspend_report_result(ops->freeze, error);
                }
                break;
        case PM_EVENT_HIBERNATE:
                if (ops->poweroff) {
                        error = ops->poweroff(dev);
                        suspend_report_result(ops->poweroff, error);
                }
                break;
        case PM_EVENT_THAW:
        case PM_EVENT_RECOVER:
                if (ops->thaw) {
                        error = ops->thaw(dev);
                        suspend_report_result(ops->thaw, error);
                }
                break;
        case PM_EVENT_RESTORE:
                if (ops->restore) {
                        error = ops->restore(dev);
                        suspend_report_result(ops->restore, error);
                }
                break;
#endif /* CONFIG_HIBERNATION */
        default:
                error = -EINVAL;
        }

        initcall_debug_report(dev, calltime, error);

        return error;
}

/**
 * pm_noirq_op - Execute the PM operation appropriate for given PM event.
 * @dev: Device to handle.
 * @ops: PM operations to choose from.
 * @state: PM transition of the system being carried out.
 *
 * The driver of @dev will not receive interrupts while this function is being
 * executed.
 */
static int pm_noirq_op(struct device *dev,
                        const struct dev_pm_ops *ops,
                        pm_message_t state)
{
        int error = 0;
        ktime_t calltime, delta, rettime;

        if (initcall_debug) {
                pr_info("calling  %s+ @ %i, parent: %s\n",
                                dev_name(dev), task_pid_nr(current),
                                dev->parent ? dev_name(dev->parent) : "none");
                calltime = ktime_get();
        }

        switch (state.event) {
#ifdef CONFIG_SUSPEND
        case PM_EVENT_SUSPEND:
                if (ops->suspend_noirq) {
                        error = ops->suspend_noirq(dev);
                        suspend_report_result(ops->suspend_noirq, error);
                }
                break;
        case PM_EVENT_RESUME:
                if (ops->resume_noirq) {
                        error = ops->resume_noirq(dev);
                        suspend_report_result(ops->resume_noirq, error);
                }
                break;
#endif /* CONFIG_SUSPEND */
#ifdef CONFIG_HIBERNATION
        case PM_EVENT_FREEZE:
        case PM_EVENT_QUIESCE:
                if (ops->freeze_noirq) {
                        error = ops->freeze_noirq(dev);
                        suspend_report_result(ops->freeze_noirq, error);
                }
                break;
        case PM_EVENT_HIBERNATE:
                if (ops->poweroff_noirq) {
                        error = ops->poweroff_noirq(dev);
                        suspend_report_result(ops->poweroff_noirq, error);
                }
                break;
        case PM_EVENT_THAW:
        case PM_EVENT_RECOVER:
                if (ops->thaw_noirq) {
                        error = ops->thaw_noirq(dev);
                        suspend_report_result(ops->thaw_noirq, error);
                }
                break;
        case PM_EVENT_RESTORE:
                if (ops->restore_noirq) {
                        error = ops->restore_noirq(dev);
                        suspend_report_result(ops->restore_noirq, error);
                }
                break;
#endif /* CONFIG_HIBERNATION */
        default:
                error = -EINVAL;
        }

        if (initcall_debug) {
                rettime = ktime_get();
                delta = ktime_sub(rettime, calltime);
                printk("initcall %s_i+ returned %d after %Ld usecs\n",
                        dev_name(dev), error,
                        (unsigned long long)ktime_to_ns(delta) >> 10);
        }

        return error;
}

static char *pm_verb(int event)
{
        switch (event) {
        case PM_EVENT_SUSPEND:
                return "suspend";
        case PM_EVENT_RESUME:
                return "resume";
        case PM_EVENT_FREEZE:
                return "freeze";
        case PM_EVENT_QUIESCE:
                return "quiesce";
        case PM_EVENT_HIBERNATE:
                return "hibernate";
        case PM_EVENT_THAW:
                return "thaw";
        case PM_EVENT_RESTORE:
                return "restore";
        case PM_EVENT_RECOVER:
                return "recover";
        default:
                return "(unknown PM event)";
        }
}

static void pm_dev_dbg(struct device *dev, pm_message_t state, char *info)
{
        dev_dbg(dev, "%s%s%s\n", info, pm_verb(state.event),
                ((state.event & PM_EVENT_SLEEP) && device_may_wakeup(dev)) ?
                ", may wakeup" : "");
}

static void pm_dev_err(struct device *dev, pm_message_t state, char *info,
                        int error)
{
        printk(KERN_ERR "PM: Device %s failed to %s%s: error %d\n",
                kobject_name(&dev->kobj), pm_verb(state.event), info, error);
}

static void dpm_show_time(ktime_t starttime, pm_message_t state, char *info)
{
        ktime_t calltime;
        u64 usecs64;
        int usecs;

        calltime = ktime_get();
        usecs64 = ktime_to_ns(ktime_sub(calltime, starttime));
        do_div(usecs64, NSEC_PER_USEC);
        usecs = usecs64;
        if (usecs == 0)
                usecs = 1;
        pr_info("PM: %s%s%s of devices complete after %ld.%03ld msecs\n",
                info ?: "", info ? " " : "", pm_verb(state.event),
                usecs / USEC_PER_MSEC, usecs % USEC_PER_MSEC);
}

/*------------------------- Resume routines -------------------------*/

/**
 * device_resume_noirq - Execute an "early resume" callback for given device.
 * @dev: Device to handle.
 * @state: PM transition of the system being carried out.
 *
 * The driver of @dev will not receive interrupts while this function is being
 * executed.
 */
static int device_resume_noirq(struct device *dev, pm_message_t state)
{
        int error = 0;

        TRACE_DEVICE(dev);
        TRACE_RESUME(0);

        if (dev->bus && dev->bus->pm) {
                pm_dev_dbg(dev, state, "EARLY ");
                error = pm_noirq_op(dev, dev->bus->pm, state);
                if (error)
                        goto End;
        }

        if (dev->type && dev->type->pm) {
                pm_dev_dbg(dev, state, "EARLY type ");
                error = pm_noirq_op(dev, dev->type->pm, state);
                if (error)
                        goto End;
        }

        if (dev->class && dev->class->pm) {
                pm_dev_dbg(dev, state, "EARLY class ");
                error = pm_noirq_op(dev, dev->class->pm, state);
        }

End:
        TRACE_RESUME(error);
        return error;
}

/**
 * dpm_resume_noirq - Execute "early resume" callbacks for non-sysdev devices.
 * @state: PM transition of the system being carried out.
 *
 * Call the "noirq" resume handlers for all devices marked as DPM_OFF_IRQ and
 * enable device drivers to receive interrupts.
 */
void dpm_resume_noirq(pm_message_t state)
{
        struct device *dev;
        ktime_t starttime = ktime_get();

        mutex_lock(&dpm_list_mtx);
        transition_started = false;
        list_for_each_entry(dev, &dpm_list, power.entry)
                if (dev->power.status > DPM_OFF) {
                        int error;

                        dev->power.status = DPM_OFF;
                        error = device_resume_noirq(dev, state);
                        if (error)
                                pm_dev_err(dev, state, " early", error);
                }
        mutex_unlock(&dpm_list_mtx);
        dpm_show_time(starttime, state, "early");
        resume_device_irqs();
}
EXPORT_SYMBOL_GPL(dpm_resume_noirq);

/**
 * legacy_resume - Execute a legacy (bus or class) resume callback for device.
 * @dev: Device to resume.
 * @cb: Resume callback to execute.
 */
static int legacy_resume(struct device *dev, int (*cb)(struct device *dev))
{
        int error;
        ktime_t calltime;

        calltime = initcall_debug_start(dev);

        error = cb(dev);
        suspend_report_result(cb, error);

        initcall_debug_report(dev, calltime, error);

        return error;
}

/**
 * device_resume - Execute "resume" callbacks for given device.
 * @dev: Device to handle.
 * @state: PM transition of the system being carried out.
 * @async: If true, the device is being resumed asynchronously.
 */
static int device_resume(struct device *dev, pm_message_t state, bool async)
{
        int error = 0;

        TRACE_DEVICE(dev);
        TRACE_RESUME(0);

        dpm_wait(dev->parent, async);
        device_lock(dev);

        dev->power.status = DPM_RESUMING;

        if (dev->bus) {
                if (dev->bus->pm) {
                        pm_dev_dbg(dev, state, "");
                        error = pm_op(dev, dev->bus->pm, state);
                } else if (dev->bus->resume) {
                        pm_dev_dbg(dev, state, "legacy ");
                        error = legacy_resume(dev, dev->bus->resume);
                }
                if (error)
                        goto End;
        }

        if (dev->type) {
                if (dev->type->pm) {
                        pm_dev_dbg(dev, state, "type ");
                        error = pm_op(dev, dev->type->pm, state);
                }
                if (error)
                        goto End;
        }

        if (dev->class) {
                if (dev->class->pm) {
                        pm_dev_dbg(dev, state, "class ");
                        error = pm_op(dev, dev->class->pm, state);
                } else if (dev->class->resume) {
                        pm_dev_dbg(dev, state, "legacy class ");
                        error = legacy_resume(dev, dev->class->resume);
                }
        }
 End:
        device_unlock(dev);
        complete_all(&dev->power.completion);

        TRACE_RESUME(error);
        return error;
}

static void async_resume(void *data, async_cookie_t cookie)
{
        struct device *dev = (struct device *)data;
        int error;

        error = device_resume(dev, pm_transition, true);
        if (error)
                pm_dev_err(dev, pm_transition, " async", error);
        put_device(dev);
}

static bool is_async(struct device *dev)
{
        return dev->power.async_suspend && pm_async_enabled
                && !pm_trace_is_enabled();
}

/**
 * dpm_resume - Execute "resume" callbacks for non-sysdev devices.
 * @state: PM transition of the system being carried out.
 *
 * Execute the appropriate "resume" callback for all devices whose status
 * indicates that they are suspended.
 */
static void dpm_resume(pm_message_t state)
{
        struct list_head list;
        struct device *dev;
        ktime_t starttime = ktime_get();

        INIT_LIST_HEAD(&list);
        mutex_lock(&dpm_list_mtx);
        pm_transition = state;
        async_error = 0;

        list_for_each_entry(dev, &dpm_list, power.entry) {
                if (dev->power.status < DPM_OFF)
                        continue;

                INIT_COMPLETION(dev->power.completion);
                if (is_async(dev)) {
                        get_device(dev);
                        async_schedule(async_resume, dev);
                }
        }

        while (!list_empty(&dpm_list)) {
                dev = to_device(dpm_list.next);
                get_device(dev);
                if (dev->power.status >= DPM_OFF && !is_async(dev)) {
                        int error;

                        mutex_unlock(&dpm_list_mtx);

                        error = device_resume(dev, state, false);

                        mutex_lock(&dpm_list_mtx);
                        if (error)
                                pm_dev_err(dev, state, "", error);
                } else if (dev->power.status == DPM_SUSPENDING) {
                        /* Allow new children of the device to be registered */
                        dev->power.status = DPM_RESUMING;
                }
                if (!list_empty(&dev->power.entry))
                        list_move_tail(&dev->power.entry, &list);
                put_device(dev);
        }
        list_splice(&list, &dpm_list);
        mutex_unlock(&dpm_list_mtx);
        async_synchronize_full();
        dpm_show_time(starttime, state, NULL);
}

/**
 * device_complete - Complete a PM transition for given device.
 * @dev: Device to handle.
 * @state: PM transition of the system being carried out.
 */
static void device_complete(struct device *dev, pm_message_t state)
{
        device_lock(dev);

        if (dev->class && dev->class->pm && dev->class->pm->complete) {
                pm_dev_dbg(dev, state, "completing class ");
                dev->class->pm->complete(dev);
        }

        if (dev->type && dev->type->pm && dev->type->pm->complete) {
                pm_dev_dbg(dev, state, "completing type ");
                dev->type->pm->complete(dev);
        }

        if (dev->bus && dev->bus->pm && dev->bus->pm->complete) {
                pm_dev_dbg(dev, state, "completing ");
                dev->bus->pm->complete(dev);
        }

        device_unlock(dev);
}

/**
 * dpm_complete - Complete a PM transition for all non-sysdev devices.
 * @state: PM transition of the system being carried out.
 *
 * Execute the ->complete() callbacks for all devices whose PM status is not
 * DPM_ON (this allows new devices to be registered).
 */
static void dpm_complete(pm_message_t state)
{
        struct list_head list;

        INIT_LIST_HEAD(&list);
        mutex_lock(&dpm_list_mtx);
        transition_started = false;
        while (!list_empty(&dpm_list)) {
                struct device *dev = to_device(dpm_list.prev);

                get_device(dev);
                if (dev->power.status > DPM_ON) {
                        dev->power.status = DPM_ON;
                        mutex_unlock(&dpm_list_mtx);

                        device_complete(dev, state);
                        pm_runtime_put_sync(dev);

                        mutex_lock(&dpm_list_mtx);
                }
                if (!list_empty(&dev->power.entry))
                        list_move(&dev->power.entry, &list);
                put_device(dev);
        }
        list_splice(&list, &dpm_list);
        mutex_unlock(&dpm_list_mtx);
}

/**
 * dpm_resume_end - Execute "resume" callbacks and complete system transition.
 * @state: PM transition of the system being carried out.
 *
 * Execute "resume" callbacks for all devices and complete the PM transition of
 * the system.
 */
void dpm_resume_end(pm_message_t state)
{
        might_sleep();
        dpm_resume(state);
        dpm_complete(state);
}
EXPORT_SYMBOL_GPL(dpm_resume_end);


/*------------------------- Suspend routines -------------------------*/

/**
 * resume_event - Return a "resume" message for given "suspend" sleep state.
 * @sleep_state: PM message representing a sleep state.
 *
 * Return a PM message representing the resume event corresponding to given
 * sleep state.
 */
static pm_message_t resume_event(pm_message_t sleep_state)
{
        switch (sleep_state.event) {
        case PM_EVENT_SUSPEND:
                return PMSG_RESUME;
        case PM_EVENT_FREEZE:
        case PM_EVENT_QUIESCE:
                return PMSG_RECOVER;
        case PM_EVENT_HIBERNATE:
                return PMSG_RESTORE;
        }
        return PMSG_ON;
}

/**
 * device_suspend_noirq - Execute a "late suspend" callback for given device.
 * @dev: Device to handle.
 * @state: PM transition of the system being carried out.
 *
 * The driver of @dev will not receive interrupts while this function is being
 * executed.
 */
static int device_suspend_noirq(struct device *dev, pm_message_t state)
{
        int error = 0;

        if (dev->class && dev->class->pm) {
                pm_dev_dbg(dev, state, "LATE class ");
                error = pm_noirq_op(dev, dev->class->pm, state);
                if (error)
                        goto End;
        }

        if (dev->type && dev->type->pm) {
                pm_dev_dbg(dev, state, "LATE type ");
                error = pm_noirq_op(dev, dev->type->pm, state);
                if (error)
                        goto End;
        }

        if (dev->bus && dev->bus->pm) {
                pm_dev_dbg(dev, state, "LATE ");
                error = pm_noirq_op(dev, dev->bus->pm, state);
        }

End:
        return error;
}

/**
 * dpm_suspend_noirq - Execute "late suspend" callbacks for non-sysdev devices.
 * @state: PM transition of the system being carried out.
 *
 * Prevent device drivers from receiving interrupts and call the "noirq" suspend
 * handlers for all non-sysdev devices.
 */
int dpm_suspend_noirq(pm_message_t state)
{
        struct device *dev;
        ktime_t starttime = ktime_get();
        int error = 0;

        suspend_device_irqs();
        mutex_lock(&dpm_list_mtx);
        list_for_each_entry_reverse(dev, &dpm_list, power.entry) {
                error = device_suspend_noirq(dev, state);
                if (error) {
                        pm_dev_err(dev, state, " late", error);
                        break;
                }
                dev->power.status = DPM_OFF_IRQ;
        }
        mutex_unlock(&dpm_list_mtx);
        if (error)
                dpm_resume_noirq(resume_event(state));
        else
                dpm_show_time(starttime, state, "late");
        return error;
}
EXPORT_SYMBOL_GPL(dpm_suspend_noirq);

/**
 * legacy_suspend - Execute a legacy (bus or class) suspend callback for device.
 * @dev: Device to suspend.
 * @state: PM transition of the system being carried out.
 * @cb: Suspend callback to execute.
 */
static int legacy_suspend(struct device *dev, pm_message_t state,
                          int (*cb)(struct device *dev, pm_message_t state))
{
        int error;
        ktime_t calltime;

        calltime = initcall_debug_start(dev);

        error = cb(dev, state);
        suspend_report_result(cb, error);

        initcall_debug_report(dev, calltime, error);

        return error;
}

/**
 * device_suspend - Execute "suspend" callbacks for given device.
 * @dev: Device to handle.
 * @state: PM transition of the system being carried out.
 * @async: If true, the device is being suspended asynchronously.
 */
static int __device_suspend(struct device *dev, pm_message_t state, bool async)
{
        int error = 0;

        dpm_wait_for_children(dev, async);
        device_lock(dev);

        if (async_error)
                goto End;

        if (dev->class) {
                if (dev->class->pm) {
                        pm_dev_dbg(dev, state, "class ");
                        error = pm_op(dev, dev->class->pm, state);
                } else if (dev->class->suspend) {
                        pm_dev_dbg(dev, state, "legacy class ");
                        error = legacy_suspend(dev, state, dev->class->suspend);
                }
                if (error)
                        goto End;
        }

        if (dev->type) {
                if (dev->type->pm) {
                        pm_dev_dbg(dev, state, "type ");
                        error = pm_op(dev, dev->type->pm, state);
                }
                if (error)
                        goto End;
        }

        if (dev->bus) {
                if (dev->bus->pm) {
                        pm_dev_dbg(dev, state, "");
                        error = pm_op(dev, dev->bus->pm, state);
                } else if (dev->bus->suspend) {
                        pm_dev_dbg(dev, state, "legacy ");
                        error = legacy_suspend(dev, state, dev->bus->suspend);
                }
        }

        if (!error)
                dev->power.status = DPM_OFF;

 End:
        device_unlock(dev);
        complete_all(&dev->power.completion);

        if (error)
                async_error = error;

        return error;
}

static void async_suspend(void *data, async_cookie_t cookie)
{
        struct device *dev = (struct device *)data;
        int error;

        error = __device_suspend(dev, pm_transition, true);
        if (error)
                pm_dev_err(dev, pm_transition, " async", error);

        put_device(dev);
}

static int device_suspend(struct device *dev)
{
        INIT_COMPLETION(dev->power.completion);

        if (pm_async_enabled && dev->power.async_suspend) {
                get_device(dev);
                async_schedule(async_suspend, dev);
                return 0;
        }

        return __device_suspend(dev, pm_transition, false);
}

/**
 * dpm_suspend - Execute "suspend" callbacks for all non-sysdev devices.
 * @state: PM transition of the system being carried out.
 */
static int dpm_suspend(pm_message_t state)
{
        struct list_head list;
        ktime_t starttime = ktime_get();
        int error = 0;

        INIT_LIST_HEAD(&list);
        mutex_lock(&dpm_list_mtx);
        pm_transition = state;
        async_error = 0;
        while (!list_empty(&dpm_list)) {
                struct device *dev = to_device(dpm_list.prev);

                get_device(dev);
                mutex_unlock(&dpm_list_mtx);

                error = device_suspend(dev);

                mutex_lock(&dpm_list_mtx);
                if (error) {
                        pm_dev_err(dev, state, "", error);
                        put_device(dev);
                        break;
                }
                if (!list_empty(&dev->power.entry))
                        list_move(&dev->power.entry, &list);
                put_device(dev);
                if (async_error)
                        break;
        }
        list_splice(&list, dpm_list.prev);
        mutex_unlock(&dpm_list_mtx);
        async_synchronize_full();
        if (!error)
                error = async_error;
        if (!error)
                dpm_show_time(starttime, state, NULL);
        return error;
}

/**
 * device_prepare - Prepare a device for system power transition.
 * @dev: Device to handle.
 * @state: PM transition of the system being carried out.
 *
 * Execute the ->prepare() callback(s) for given device.  No new children of the
 * device may be registered after this function has returned.
 */
static int device_prepare(struct device *dev, pm_message_t state)
{
        int error = 0;

        device_lock(dev);

        if (dev->bus && dev->bus->pm && dev->bus->pm->prepare) {
                pm_dev_dbg(dev, state, "preparing ");
                error = dev->bus->pm->prepare(dev);
                suspend_report_result(dev->bus->pm->prepare, error);
                if (error)
                        goto End;
        }

        if (dev->type && dev->type->pm && dev->type->pm->prepare) {
                pm_dev_dbg(dev, state, "preparing type ");
                error = dev->type->pm->prepare(dev);
                suspend_report_result(dev->type->pm->prepare, error);
                if (error)
                        goto End;
        }

        if (dev->class && dev->class->pm && dev->class->pm->prepare) {
                pm_dev_dbg(dev, state, "preparing class ");
                error = dev->class->pm->prepare(dev);
                suspend_report_result(dev->class->pm->prepare, error);
        }
 End:
        device_unlock(dev);

        return error;
}

/**
 * dpm_prepare - Prepare all non-sysdev devices for a system PM transition.
 * @state: PM transition of the system being carried out.
 *
 * Execute the ->prepare() callback(s) for all devices.
 */
static int dpm_prepare(pm_message_t state)
{
        struct list_head list;
        int error = 0;

        INIT_LIST_HEAD(&list);
        mutex_lock(&dpm_list_mtx);
        transition_started = true;
        while (!list_empty(&dpm_list)) {
                struct device *dev = to_device(dpm_list.next);

                get_device(dev);
                dev->power.status = DPM_PREPARING;
                mutex_unlock(&dpm_list_mtx);

                pm_runtime_get_noresume(dev);
                if (pm_runtime_barrier(dev) && device_may_wakeup(dev)) {
                        /* Wake-up requested during system sleep transition. */
                        pm_runtime_put_sync(dev);
                        error = -EBUSY;
                } else {
                        error = device_prepare(dev, state);
                }

                mutex_lock(&dpm_list_mtx);
                if (error) {
                        dev->power.status = DPM_ON;
                        if (error == -EAGAIN) {
                                put_device(dev);
                                error = 0;
                                continue;
                        }
                        printk(KERN_ERR "PM: Failed to prepare device %s "
                                "for power transition: error %d\n",
                                kobject_name(&dev->kobj), error);
                        put_device(dev);
                        break;
                }
                dev->power.status = DPM_SUSPENDING;
                if (!list_empty(&dev->power.entry))
                        list_move_tail(&dev->power.entry, &list);
                put_device(dev);
        }
        list_splice(&list, &dpm_list);
        mutex_unlock(&dpm_list_mtx);
        return error;
}

/**
 * dpm_suspend_start - Prepare devices for PM transition and suspend them.
 * @state: PM transition of the system being carried out.
 *
 * Prepare all non-sysdev devices for system PM transition and execute "suspend"
 * callbacks for them.
 */
int dpm_suspend_start(pm_message_t state)
{
        int error;

        might_sleep();
        error = dpm_prepare(state);
        if (!error)
                error = dpm_suspend(state);
        return error;
}
EXPORT_SYMBOL_GPL(dpm_suspend_start);

void __suspend_report_result(const char *function, void *fn, int ret)
{
        if (ret)
                printk(KERN_ERR "%s(): %pF returns %d\n", function, fn, ret);
}
EXPORT_SYMBOL_GPL(__suspend_report_result);

/**
 * device_pm_wait_for_dev - Wait for suspend/resume of a device to complete.
 * @dev: Device to wait for.
 * @subordinate: Device that needs to wait for @dev.
 */
int device_pm_wait_for_dev(struct device *subordinate, struct device *dev)
{
        dpm_wait(dev, subordinate->power.async_suspend);
        return async_error;
}
EXPORT_SYMBOL_GPL(device_pm_wait_for_dev);