/*
 *	scsi_pm.c	Copyright (C) 2010 Alan Stern
 *
 *	SCSI dynamic Power Management
 *		Initial version: Alan Stern <stern@rowland.harvard.edu>
 */

#include <linux/pm_runtime.h>
#include <linux/export.h>
#include <linux/async.h>

#include <scsi/scsi.h>
#include <scsi/scsi_device.h>
#include <scsi/scsi_driver.h>
#include <scsi/scsi_host.h>

#include "scsi_priv.h"

static int scsi_dev_type_suspend(struct device *dev, pm_message_t msg)
{
	struct device_driver *drv;
	int err;

	err = scsi_device_quiesce(to_scsi_device(dev));
	if (err == 0) {
		drv = dev->driver;
		if (drv && drv->suspend)
			err = drv->suspend(dev, msg);
	}
	dev_dbg(dev, "scsi suspend: %d\n", err);
	return err;
}

static int scsi_dev_type_resume(struct device *dev)
{
	struct device_driver *drv;
	int err = 0;

	drv = dev->driver;
	if (drv && drv->resume)
		err = drv->resume(dev);
	scsi_device_resume(to_scsi_device(dev));
	dev_dbg(dev, "scsi resume: %d\n", err);
	return err;
}

#ifdef CONFIG_PM_SLEEP

static int scsi_bus_suspend_common(struct device *dev, pm_message_t msg)
{
	int err = 0;

	if (scsi_is_sdev_device(dev)) {
		/*
		 * sd is the only high-level SCSI driver to implement runtime
		 * PM, and sd treats runtime suspend, system suspend, and
		 * system hibernate identically (but not system freeze).
		 */
		if (pm_runtime_suspended(dev)) {
			if (msg.event == PM_EVENT_SUSPEND ||
			    msg.event == PM_EVENT_HIBERNATE)
				return 0;	/* already suspended */

			/* wake up device so that FREEZE will succeed */
			pm_runtime_resume(dev);
		}
		err = scsi_dev_type_suspend(dev, msg);
	}
	return err;
}

static int scsi_bus_resume_common(struct device *dev)
{
	int err = 0;

	if (scsi_is_sdev_device(dev)) {
		/*
		 * Parent device may have runtime suspended as soon as
		 * it is woken up during the system resume.
		 *
		 * Resume it on behalf of child.
		 */
		pm_runtime_get_sync(dev->parent);
		err = scsi_dev_type_resume(dev);
		pm_runtime_put_sync(dev->parent);
	}

	if (err == 0) {
		pm_runtime_disable(dev);
		pm_runtime_set_active(dev);
		pm_runtime_enable(dev);
	}
	return err;
}

static int scsi_bus_prepare(struct device *dev)
{
	if (scsi_is_sdev_device(dev)) {
		/* sd probing uses async_schedule.  Wait until it finishes. */
		async_synchronize_full();

	} else if (scsi_is_host_device(dev)) {
		/* Wait until async scanning is finished */
		scsi_complete_async_scans();
	}
	return 0;
}

static int scsi_bus_suspend(struct device *dev)
{
	return scsi_bus_suspend_common(dev, PMSG_SUSPEND);
}

static int scsi_bus_freeze(struct device *dev)
{
	return scsi_bus_suspend_common(dev, PMSG_FREEZE);
}

static int scsi_bus_poweroff(struct device *dev)
{
	return scsi_bus_suspend_common(dev, PMSG_HIBERNATE);
}

#else /* CONFIG_PM_SLEEP */

#define scsi_bus_resume_common		NULL
#define scsi_bus_prepare		NULL
#define scsi_bus_suspend		NULL
#define scsi_bus_freeze			NULL
#define scsi_bus_poweroff		NULL

#endif /* CONFIG_PM_SLEEP */

#ifdef CONFIG_PM_RUNTIME

static int scsi_runtime_suspend(struct device *dev)
{
	int err = 0;

	dev_dbg(dev, "scsi_runtime_suspend\n");
	if (scsi_is_sdev_device(dev)) {
		err = scsi_dev_type_suspend(dev, PMSG_AUTO_SUSPEND);
		if (err == -EAGAIN)
			pm_schedule_suspend(dev, jiffies_to_msecs(
				round_jiffies_up_relative(HZ/10)));
	}

	/* Insert hooks here for targets, hosts, and transport classes */

	return err;
}

static int scsi_runtime_resume(struct device *dev)
{
	int err = 0;

	dev_dbg(dev, "scsi_runtime_resume\n");
	if (scsi_is_sdev_device(dev))
		err = scsi_dev_type_resume(dev);

	/* Insert hooks here for targets, hosts, and transport classes */

	return err;
}

static int scsi_runtime_idle(struct device *dev)
{
	int err;

	dev_dbg(dev, "scsi_runtime_idle\n");

	/* Insert hooks here for targets, hosts, and transport classes */

	if (scsi_is_sdev_device(dev))
		err = pm_schedule_suspend(dev, 100);
	else
		err = pm_runtime_suspend(dev);
	return err;
}

int scsi_autopm_get_device(struct scsi_device *sdev)
{
	int	err;

	err = pm_runtime_get_sync(&sdev->sdev_gendev);
	if (err < 0 && err !=-EACCES)
		pm_runtime_put_sync(&sdev->sdev_gendev);
	else
		err = 0;
	return err;
}
EXPORT_SYMBOL_GPL(scsi_autopm_get_device);

void scsi_autopm_put_device(struct scsi_device *sdev)
{
	pm_runtime_put_sync(&sdev->sdev_gendev);
}
EXPORT_SYMBOL_GPL(scsi_autopm_put_device);

void scsi_autopm_get_target(struct scsi_target *starget)
{
	pm_runtime_get_sync(&starget->dev);
}

void scsi_autopm_put_target(struct scsi_target *starget)
{
	pm_runtime_put_sync(&starget->dev);
}

int scsi_autopm_get_host(struct Scsi_Host *shost)
{
	int	err;

	err = pm_runtime_get_sync(&shost->shost_gendev);
	if (err < 0 && err !=-EACCES)
		pm_runtime_put_sync(&shost->shost_gendev);
	else
		err = 0;
	return err;
}

void scsi_autopm_put_host(struct Scsi_Host *shost)
{
	pm_runtime_put_sync(&shost->shost_gendev);
}

#else

#define scsi_runtime_suspend	NULL
#define scsi_runtime_resume	NULL
#define scsi_runtime_idle	NULL

#endif /* CONFIG_PM_RUNTIME */

const struct dev_pm_ops scsi_bus_pm_ops = {
	.prepare =		scsi_bus_prepare,
	.suspend =		scsi_bus_suspend,
	.resume =		scsi_bus_resume_common,
	.freeze =		scsi_bus_freeze,
	.thaw =			scsi_bus_resume_common,
	.poweroff =		scsi_bus_poweroff,
	.restore =		scsi_bus_resume_common,
	.runtime_suspend =	scsi_runtime_suspend,
	.runtime_resume =	scsi_runtime_resume,
	.runtime_idle =		scsi_runtime_idle,
};