main.c 20.9 KB
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/*
 * 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 intialize 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.
 *
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 * 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.
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 */

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

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/*
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 * The entries in the dpm_list list are in a depth first order, simply
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 * 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 semaphore held,
 * we must never try to acquire a device semaphore while holding
 * dpm_list_mutex.
 */

42
LIST_HEAD(dpm_list);
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static DEFINE_MUTEX(dpm_list_mtx);
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/*
 * 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;

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

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

/**
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 * device_pm_unlock - Unlock the list of active devices used by the PM core.
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 */
void device_pm_unlock(void)
{
	mutex_unlock(&dpm_list_mtx);
}
77

78
/**
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 * device_pm_add - Add a device to the PM core's list of active devices.
 * @dev: Device to add to the list.
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 */
82
void device_pm_add(struct device *dev)
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{
	pr_debug("PM: Adding info for %s:%s\n",
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		 dev->bus ? dev->bus->name : "No Bus",
		 kobject_name(&dev->kobj));
87
	mutex_lock(&dpm_list_mtx);
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	if (dev->parent) {
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		if (dev->parent->power.status >= DPM_SUSPENDING)
			dev_warn(dev, "parent %s should not be sleeping\n",
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				 dev_name(dev->parent));
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	} 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
		 */
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		dev_WARN(dev, "Parentless device registered during a PM transaction\n");
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	}
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	list_add_tail(&dev->power.entry, &dpm_list);
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	mutex_unlock(&dpm_list_mtx);
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}

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

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/**
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 * 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.
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 */
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);
}

/**
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 * 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.
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 */
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);
}

/**
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 * device_pm_move_last - Move device to end of the PM core's list of devices.
 * @dev: Device to move in dpm_list.
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 */
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);
}

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/**
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 * 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.
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 */
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static int pm_op(struct device *dev,
		 const struct dev_pm_ops *ops,
		 pm_message_t state)
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{
	int error = 0;
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	ktime_t calltime, delta, rettime;

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

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	return error;
}

/**
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 * 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.
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 *
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 * The driver of @dev will not receive interrupts while this function is being
 * executed.
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 */
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static int pm_noirq_op(struct device *dev,
			const struct dev_pm_ops *ops,
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			pm_message_t state)
{
	int error = 0;
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	ktime_t calltime, delta, rettime;

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

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	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);
}

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

/**
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 * device_resume_noirq - Execute an "early resume" callback for given device.
 * @dev: Device to handle.
 * @state: PM transition of the system being carried out.
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 *
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 * The driver of @dev will not receive interrupts while this function is being
 * executed.
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 */
367
static int device_resume_noirq(struct device *dev, pm_message_t state)
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{
	int error = 0;

	TRACE_DEVICE(dev);
	TRACE_RESUME(0);

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

/**
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 * dpm_resume_noirq - Execute "early resume" callbacks for non-sysdev devices.
 * @state: PM transition of the system being carried out.
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 *
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 * Call the "noirq" resume handlers for all devices marked as DPM_OFF_IRQ and
 * enable device drivers to receive interrupts.
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 */
390
void dpm_resume_noirq(pm_message_t state)
391
{
392
	struct device *dev;
393

394
	mutex_lock(&dpm_list_mtx);
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	transition_started = false;
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	list_for_each_entry(dev, &dpm_list, power.entry)
		if (dev->power.status > DPM_OFF) {
			int error;
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400
			dev->power.status = DPM_OFF;
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			error = device_resume_noirq(dev, state);
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			if (error)
				pm_dev_err(dev, state, " early", error);
		}
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	mutex_unlock(&dpm_list_mtx);
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	resume_device_irqs();
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}
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EXPORT_SYMBOL_GPL(dpm_resume_noirq);
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/**
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 * device_resume - Execute "resume" callbacks for given device.
 * @dev: Device to handle.
 * @state: PM transition of the system being carried out.
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 */
415
static int device_resume(struct device *dev, pm_message_t state)
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{
	int error = 0;

	TRACE_DEVICE(dev);
	TRACE_RESUME(0);
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422 423
	down(&dev->sem);

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

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	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;
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	}

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	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 = dev->class->resume(dev);
		}
453
	}
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 End:
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	up(&dev->sem);

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	TRACE_RESUME(error);
	return error;
}

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/**
462 463
 * dpm_resume - Execute "resume" callbacks for non-sysdev devices.
 * @state: PM transition of the system being carried out.
464
 *
465 466
 * Execute the appropriate "resume" callback for all devices whose status
 * indicates that they are suspended.
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 */
static void dpm_resume(pm_message_t state)
{
	struct list_head list;

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

		get_device(dev);
		if (dev->power.status >= DPM_OFF) {
			int error;

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

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			error = device_resume(dev, state);
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			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);
}

/**
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 * device_complete - Complete a PM transition for given device.
 * @dev: Device to handle.
 * @state: PM transition of the system being carried out.
505
 */
506
static void device_complete(struct device *dev, pm_message_t state)
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{
	down(&dev->sem);

	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);
	}

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

	up(&dev->sem);
}

/**
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 * dpm_complete - Complete a PM transition for all non-sysdev devices.
 * @state: PM transition of the system being carried out.
531
 *
532 533
 * Execute the ->complete() callbacks for all devices whose PM status is not
 * DPM_ON (this allows new devices to be registered).
534
 */
535
static void dpm_complete(pm_message_t state)
536
{
537 538 539
	struct list_head list;

	INIT_LIST_HEAD(&list);
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	mutex_lock(&dpm_list_mtx);
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	transition_started = false;
542 543
	while (!list_empty(&dpm_list)) {
		struct device *dev = to_device(dpm_list.prev);
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		get_device(dev);
		if (dev->power.status > DPM_ON) {
			dev->power.status = DPM_ON;
			mutex_unlock(&dpm_list_mtx);

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

/**
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 * dpm_resume_end - Execute "resume" callbacks and complete system transition.
 * @state: PM transition of the system being carried out.
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 *
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 * Execute "resume" callbacks for all devices and complete the PM transition of
 * the system.
569
 */
570
void dpm_resume_end(pm_message_t state)
571
{
572
	might_sleep();
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	dpm_resume(state);
	dpm_complete(state);
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}
576
EXPORT_SYMBOL_GPL(dpm_resume_end);
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/*------------------------- Suspend routines -------------------------*/

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/**
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 * 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.
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 */
static pm_message_t resume_event(pm_message_t sleep_state)
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{
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	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;
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	}
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	return PMSG_ON;
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}

/**
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 * device_suspend_noirq - Execute a "late suspend" callback for given device.
 * @dev: Device to handle.
 * @state: PM transition of the system being carried out.
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 *
607 608
 * The driver of @dev will not receive interrupts while this function is being
 * executed.
609
 */
610
static int device_suspend_noirq(struct device *dev, pm_message_t state)
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{
	int error = 0;
613

614
	if (dev->bus && dev->bus->pm) {
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		pm_dev_dbg(dev, state, "LATE ");
		error = pm_noirq_op(dev, dev->bus->pm, state);
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	}
	return error;
}

/**
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 * dpm_suspend_noirq - Execute "late suspend" callbacks for non-sysdev devices.
 * @state: PM transition of the system being carried out.
624
 *
625 626
 * Prevent device drivers from receiving interrupts and call the "noirq" suspend
 * handlers for all non-sysdev devices.
627
 */
628
int dpm_suspend_noirq(pm_message_t state)
629
{
630
	struct device *dev;
631 632
	int error = 0;

633
	suspend_device_irqs();
634
	mutex_lock(&dpm_list_mtx);
635
	list_for_each_entry_reverse(dev, &dpm_list, power.entry) {
636
		error = device_suspend_noirq(dev, state);
637
		if (error) {
638
			pm_dev_err(dev, state, " late", error);
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			break;
		}
641
		dev->power.status = DPM_OFF_IRQ;
642
	}
643
	mutex_unlock(&dpm_list_mtx);
644
	if (error)
645
		dpm_resume_noirq(resume_event(state));
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	return error;
}
648
EXPORT_SYMBOL_GPL(dpm_suspend_noirq);
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/**
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 * device_suspend - Execute "suspend" callbacks for given device.
 * @dev: Device to handle.
 * @state: PM transition of the system being carried out.
654
 */
655
static int device_suspend(struct device *dev, pm_message_t state)
656 657 658
{
	int error = 0;

659 660
	down(&dev->sem);

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	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 = dev->class->suspend(dev, state);
			suspend_report_result(dev->class->suspend, error);
		}
		if (error)
			goto End;
672 673
	}

674 675 676 677 678 679 680
	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;
681 682
	}

683 684 685
	if (dev->bus) {
		if (dev->bus->pm) {
			pm_dev_dbg(dev, state, "");
686
			error = pm_op(dev, dev->bus->pm, state);
687 688 689 690 691
		} else if (dev->bus->suspend) {
			pm_dev_dbg(dev, state, "legacy ");
			error = dev->bus->suspend(dev, state);
			suspend_report_result(dev->bus->suspend, error);
		}
692
	}
693
 End:
694 695
	up(&dev->sem);

696 697 698 699
	return error;
}

/**
700 701
 * dpm_suspend - Execute "suspend" callbacks for all non-sysdev devices.
 * @state: PM transition of the system being carried out.
702
 */
703
static int dpm_suspend(pm_message_t state)
704
{
705
	struct list_head list;
706 707
	int error = 0;

708
	INIT_LIST_HEAD(&list);
709
	mutex_lock(&dpm_list_mtx);
710 711
	while (!list_empty(&dpm_list)) {
		struct device *dev = to_device(dpm_list.prev);
712

713
		get_device(dev);
714
		mutex_unlock(&dpm_list_mtx);
715

716
		error = device_suspend(dev, state);
717

718
		mutex_lock(&dpm_list_mtx);
719
		if (error) {
720 721
			pm_dev_err(dev, state, "", error);
			put_device(dev);
722 723
			break;
		}
724
		dev->power.status = DPM_OFF;
725
		if (!list_empty(&dev->power.entry))
726 727
			list_move(&dev->power.entry, &list);
		put_device(dev);
728
	}
729
	list_splice(&list, dpm_list.prev);
730
	mutex_unlock(&dpm_list_mtx);
731 732 733 734
	return error;
}

/**
735 736 737 738 739 740
 * 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.
741
 */
742
static int device_prepare(struct device *dev, pm_message_t state)
743 744 745 746 747
{
	int error = 0;

	down(&dev->sem);

748
	if (dev->bus && dev->bus->pm && dev->bus->pm->prepare) {
749
		pm_dev_dbg(dev, state, "preparing ");
750 751
		error = dev->bus->pm->prepare(dev);
		suspend_report_result(dev->bus->pm->prepare, error);
752 753 754 755 756 757 758 759 760 761 762 763 764 765 766 767 768 769 770 771 772 773
		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:
	up(&dev->sem);

	return error;
}
774

775
/**
776 777
 * dpm_prepare - Prepare all non-sysdev devices for a system PM transition.
 * @state: PM transition of the system being carried out.
778
 *
779
 * Execute the ->prepare() callback(s) for all devices.
780 781 782 783 784 785 786 787 788 789 790 791 792 793 794 795
 */
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);

796 797 798 799 800 801 802 803
		pm_runtime_get_noresume(dev);
		if (pm_runtime_barrier(dev) && device_may_wakeup(dev)) {
			/* Wake-up requested during system sleep transition. */
			pm_runtime_put_noidle(dev);
			error = -EBUSY;
		} else {
			error = device_prepare(dev, state);
		}
804 805 806 807 808 809

		mutex_lock(&dpm_list_mtx);
		if (error) {
			dev->power.status = DPM_ON;
			if (error == -EAGAIN) {
				put_device(dev);
S
Sebastian Ott 已提交
810
				error = 0;
811 812 813 814 815 816 817 818 819 820 821 822 823 824 825
				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);
826 827 828
	return error;
}

829
/**
830 831
 * dpm_suspend_start - Prepare devices for PM transition and suspend them.
 * @state: PM transition of the system being carried out.
832
 *
833 834
 * Prepare all non-sysdev devices for system PM transition and execute "suspend"
 * callbacks for them.
835
 */
836
int dpm_suspend_start(pm_message_t state)
837 838
{
	int error;
839

840
	might_sleep();
841 842 843
	error = dpm_prepare(state);
	if (!error)
		error = dpm_suspend(state);
844 845
	return error;
}
846
EXPORT_SYMBOL_GPL(dpm_suspend_start);
847 848 849

void __suspend_report_result(const char *function, void *fn, int ret)
{
850 851
	if (ret)
		printk(KERN_ERR "%s(): %pF returns %d\n", function, fn, ret);
852 853
}
EXPORT_SYMBOL_GPL(__suspend_report_result);