/*
 *      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"

#ifdef CONFIG_PM_SLEEP

static int do_scsi_suspend(struct device *dev, const struct dev_pm_ops *pm)
{
        return pm && pm->suspend ? pm->suspend(dev) : 0;
}

static int do_scsi_freeze(struct device *dev, const struct dev_pm_ops *pm)
{
        return pm && pm->freeze ? pm->freeze(dev) : 0;
}

static int do_scsi_poweroff(struct device *dev, const struct dev_pm_ops *pm)
{
        return pm && pm->poweroff ? pm->poweroff(dev) : 0;
}

static int do_scsi_resume(struct device *dev, const struct dev_pm_ops *pm)
{
        return pm && pm->resume ? pm->resume(dev) : 0;
}

static int do_scsi_thaw(struct device *dev, const struct dev_pm_ops *pm)
{
        return pm && pm->thaw ? pm->thaw(dev) : 0;
}

static int do_scsi_restore(struct device *dev, const struct dev_pm_ops *pm)
{
        return pm && pm->restore ? pm->restore(dev) : 0;
}

static int scsi_dev_type_suspend(struct device *dev,
                int (*cb)(struct device *, const struct dev_pm_ops *))
{
        const struct dev_pm_ops *pm = dev->driver ? dev->driver->pm : NULL;
        int err;

        /* flush pending in-flight resume operations, suspend is synchronous */
        async_synchronize_full_domain(&scsi_sd_pm_domain);

        err = scsi_device_quiesce(to_scsi_device(dev));
        if (err == 0) {
                err = cb(dev, pm);
                if (err)
                        scsi_device_resume(to_scsi_device(dev));
        }
        dev_dbg(dev, "scsi suspend: %d\n", err);
        return err;
}

static int scsi_dev_type_resume(struct device *dev,
                int (*cb)(struct device *, const struct dev_pm_ops *))
{
        const struct dev_pm_ops *pm = dev->driver ? dev->driver->pm : NULL;
        int err = 0;

        err = cb(dev, pm);
        scsi_device_resume(to_scsi_device(dev));
        dev_dbg(dev, "scsi resume: %d\n", err);

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

        return err;
}

static int
scsi_bus_suspend_common(struct device *dev,
                int (*cb)(struct device *, const struct dev_pm_ops *))
{
        int err = 0;

        if (scsi_is_sdev_device(dev)) {
                /*
                 * All the high-level SCSI drivers that implement runtime
                 * PM treat runtime suspend, system suspend, and system
                 * hibernate nearly identically. In all cases the requirements
                 * for runtime suspension are stricter.
                 */
                if (pm_runtime_suspended(dev))
                        return 0;

                err = scsi_dev_type_suspend(dev, cb);
        }

        return err;
}

static void async_sdev_resume(void *dev, async_cookie_t cookie)
{
        scsi_dev_type_resume(dev, do_scsi_resume);
}

static void async_sdev_thaw(void *dev, async_cookie_t cookie)
{
        scsi_dev_type_resume(dev, do_scsi_thaw);
}

static void async_sdev_restore(void *dev, async_cookie_t cookie)
{
        scsi_dev_type_resume(dev, do_scsi_restore);
}

static int scsi_bus_resume_common(struct device *dev,
                int (*cb)(struct device *, const struct dev_pm_ops *))
{
        async_func_t fn;

        if (!scsi_is_sdev_device(dev))
                fn = NULL;
        else if (cb == do_scsi_resume)
                fn = async_sdev_resume;
        else if (cb == do_scsi_thaw)
                fn = async_sdev_thaw;
        else if (cb == do_scsi_restore)
                fn = async_sdev_restore;
        else
                fn = NULL;

        /*
         * Forcibly set runtime PM status of request queue to "active" to
         * make sure we can again get requests from the queue (see also
         * blk_pm_peek_request()).
         *
         * The resume hook will correct runtime PM status of the disk.
         */
        if (scsi_is_sdev_device(dev) && pm_runtime_suspended(dev))
                blk_set_runtime_active(to_scsi_device(dev)->request_queue);

        if (fn) {
                async_schedule_domain(fn, dev, &scsi_sd_pm_domain);

                /*
                 * If a user has disabled async probing a likely reason
                 * is due to a storage enclosure that does not inject
                 * staggered spin-ups.  For safety, make resume
                 * synchronous as well in that case.
                 */
                if (strncmp(scsi_scan_type, "async", 5) != 0)
                        async_synchronize_full_domain(&scsi_sd_pm_domain);
        } else {
                pm_runtime_disable(dev);
                pm_runtime_set_active(dev);
                pm_runtime_enable(dev);
        }
        return 0;
}

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_domain(&scsi_sd_probe_domain);

        } 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, do_scsi_suspend);
}

static int scsi_bus_resume(struct device *dev)
{
        return scsi_bus_resume_common(dev, do_scsi_resume);
}

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

static int scsi_bus_thaw(struct device *dev)
{
        return scsi_bus_resume_common(dev, do_scsi_thaw);
}

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

static int scsi_bus_restore(struct device *dev)
{
        return scsi_bus_resume_common(dev, do_scsi_restore);
}

#else /* CONFIG_PM_SLEEP */

#define scsi_bus_prepare                NULL
#define scsi_bus_suspend                NULL
#define scsi_bus_resume                 NULL
#define scsi_bus_freeze                 NULL
#define scsi_bus_thaw                   NULL
#define scsi_bus_poweroff               NULL
#define scsi_bus_restore                NULL

#endif /* CONFIG_PM_SLEEP */

static int sdev_runtime_suspend(struct device *dev)
{
        const struct dev_pm_ops *pm = dev->driver ? dev->driver->pm : NULL;
        struct scsi_device *sdev = to_scsi_device(dev);
        int err = 0;

        err = blk_pre_runtime_suspend(sdev->request_queue);
        if (err)
                return err;
        if (pm && pm->runtime_suspend)
                err = pm->runtime_suspend(dev);
        blk_post_runtime_suspend(sdev->request_queue, err);

        return err;
}

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 = sdev_runtime_suspend(dev);

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

        return err;
}

static int sdev_runtime_resume(struct device *dev)
{
        struct scsi_device *sdev = to_scsi_device(dev);
        const struct dev_pm_ops *pm = dev->driver ? dev->driver->pm : NULL;
        int err = 0;

        blk_pre_runtime_resume(sdev->request_queue);
        if (pm && pm->runtime_resume)
                err = pm->runtime_resume(dev);
        blk_post_runtime_resume(sdev->request_queue, err);

        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 = sdev_runtime_resume(dev);

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

        return err;
}

static int scsi_runtime_idle(struct device *dev)
{
        dev_dbg(dev, "scsi_runtime_idle\n");

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

        if (scsi_is_sdev_device(dev)) {
                pm_runtime_mark_last_busy(dev);
                pm_runtime_autosuspend(dev);
                return -EBUSY;
        }

        return 0;
}

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);
}

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