/*
 * arch/sh/kernel/cpu/shmobile/pm_runtime.c
 *
 * Runtime PM support code for SuperH Mobile
 *
 *  Copyright (C) 2009 Magnus Damm
 *
 * This file is subject to the terms and conditions of the GNU General Public
 * License.  See the file "COPYING" in the main directory of this archive
 * for more details.
 */
#include <linux/init.h>
#include <linux/kernel.h>
#include <linux/io.h>
#include <linux/pm_runtime.h>
#include <linux/platform_device.h>
#include <linux/mutex.h>
#include <asm/hwblk.h>

static DEFINE_SPINLOCK(hwblk_lock);
static LIST_HEAD(hwblk_idle_list);
static struct work_struct hwblk_work;

extern struct hwblk_info *hwblk_info;

static void platform_pm_runtime_not_idle(struct platform_device *pdev)
{
        unsigned long flags;

        /* remove device from idle list */
        spin_lock_irqsave(&hwblk_lock, flags);
        if (test_bit(PDEV_ARCHDATA_FLAG_IDLE, &pdev->archdata.flags)) {
                list_del(&pdev->archdata.entry);
                __clear_bit(PDEV_ARCHDATA_FLAG_IDLE, &pdev->archdata.flags);
        }
        spin_unlock_irqrestore(&hwblk_lock, flags);
}

static int __platform_pm_runtime_resume(struct platform_device *pdev)
{
        struct device *d = &pdev->dev;
        struct pdev_archdata *ad = &pdev->archdata;
        int hwblk = ad->hwblk_id;
        int ret = -ENOSYS;

        dev_dbg(d, "__platform_pm_runtime_resume() [%d]\n", hwblk);

        if (d->driver && d->driver->pm && d->driver->pm->runtime_resume) {
                hwblk_enable(hwblk_info, hwblk);
                ret = 0;

                if (test_bit(PDEV_ARCHDATA_FLAG_SUSP, &ad->flags)) {
                        ret = d->driver->pm->runtime_resume(d);
                        if (!ret)
                                clear_bit(PDEV_ARCHDATA_FLAG_SUSP, &ad->flags);
                        else
                                hwblk_disable(hwblk_info, hwblk);
                }
        }

        dev_dbg(d, "__platform_pm_runtime_resume() [%d] - returns %d\n",
                hwblk, ret);

        return ret;
}

static int __platform_pm_runtime_suspend(struct platform_device *pdev)
{
        struct device *d = &pdev->dev;
        struct pdev_archdata *ad = &pdev->archdata;
        int hwblk = ad->hwblk_id;
        int ret = -ENOSYS;

        dev_dbg(d, "__platform_pm_runtime_suspend() [%d]\n", hwblk);

        if (d->driver && d->driver->pm && d->driver->pm->runtime_suspend) {
                BUG_ON(!test_bit(PDEV_ARCHDATA_FLAG_IDLE, &ad->flags));

                hwblk_enable(hwblk_info, hwblk);
                ret = d->driver->pm->runtime_suspend(d);
                hwblk_disable(hwblk_info, hwblk);

                if (!ret) {
                        set_bit(PDEV_ARCHDATA_FLAG_SUSP, &ad->flags);
                        platform_pm_runtime_not_idle(pdev);
                        hwblk_cnt_dec(hwblk_info, hwblk, HWBLK_CNT_IDLE);
                }
        }

        dev_dbg(d, "__platform_pm_runtime_suspend() [%d] - returns %d\n",
                hwblk, ret);

        return ret;
}

static void platform_pm_runtime_work(struct work_struct *work)
{
        struct platform_device *pdev;
        unsigned long flags;
        int ret;

        /* go through the idle list and suspend one device at a time */
        do {
                spin_lock_irqsave(&hwblk_lock, flags);
                if (list_empty(&hwblk_idle_list))
                        pdev = NULL;
                else
                        pdev = list_first_entry(&hwblk_idle_list,
                                                struct platform_device,
                                                archdata.entry);
                spin_unlock_irqrestore(&hwblk_lock, flags);

                if (pdev) {
                        mutex_lock(&pdev->archdata.mutex);
                        ret = __platform_pm_runtime_suspend(pdev);

                        /* at this point the platform device may be:
                         * suspended: ret = 0, FLAG_SUSP set, clock stopped
                         * failed: ret < 0, FLAG_IDLE set, clock stopped
                         */
                        mutex_unlock(&pdev->archdata.mutex);
                } else {
                        ret = -ENODEV;
                }
        } while (!ret);
}

/* this function gets called from cpuidle context when all devices in the
 * main power domain are unused but some are counted as idle, ie the hwblk
 * counter values are (HWBLK_CNT_USAGE == 0) && (HWBLK_CNT_IDLE != 0)
 */
void platform_pm_runtime_suspend_idle(void)
{
        queue_work(pm_wq, &hwblk_work);
}

int platform_pm_runtime_suspend(struct device *dev)
{
        struct platform_device *pdev = to_platform_device(dev);
        struct pdev_archdata *ad = &pdev->archdata;
        unsigned long flags;
        int hwblk = ad->hwblk_id;
        int ret = 0;

        dev_dbg(dev, "platform_pm_runtime_suspend() [%d]\n", hwblk);

        /* ignore off-chip platform devices */
        if (!hwblk)
                goto out;

        /* interrupt context not allowed */
        might_sleep();

        /* catch misconfigured drivers not starting with resume */
        if (test_bit(PDEV_ARCHDATA_FLAG_INIT, &pdev->archdata.flags)) {
                ret = -EINVAL;
                goto out;
        }

        /* serialize */
        mutex_lock(&ad->mutex);

        /* disable clock */
        hwblk_disable(hwblk_info, hwblk);

        /* put device on idle list */
        spin_lock_irqsave(&hwblk_lock, flags);
        list_add_tail(&pdev->archdata.entry, &hwblk_idle_list);
        __set_bit(PDEV_ARCHDATA_FLAG_IDLE, &pdev->archdata.flags);
        spin_unlock_irqrestore(&hwblk_lock, flags);

        /* increase idle count */
        hwblk_cnt_inc(hwblk_info, hwblk, HWBLK_CNT_IDLE);

        /* at this point the platform device is:
         * idle: ret = 0, FLAG_IDLE set, clock stopped
         */
        mutex_unlock(&ad->mutex);

out:
        dev_dbg(dev, "platform_pm_runtime_suspend() [%d] returns %d\n",
                hwblk, ret);

        return ret;
}

int platform_pm_runtime_resume(struct device *dev)
{
        struct platform_device *pdev = to_platform_device(dev);
        struct pdev_archdata *ad = &pdev->archdata;
        int hwblk = ad->hwblk_id;
        int ret = 0;

        dev_dbg(dev, "platform_pm_runtime_resume() [%d]\n", hwblk);

        /* ignore off-chip platform devices */
        if (!hwblk)
                goto out;

        /* interrupt context not allowed */
        might_sleep();

        /* serialize */
        mutex_lock(&ad->mutex);

        /* make sure device is removed from idle list */
        platform_pm_runtime_not_idle(pdev);

        /* decrease idle count */
        if (!test_bit(PDEV_ARCHDATA_FLAG_INIT, &pdev->archdata.flags) &&
            !test_bit(PDEV_ARCHDATA_FLAG_SUSP, &pdev->archdata.flags))
                hwblk_cnt_dec(hwblk_info, hwblk, HWBLK_CNT_IDLE);

        /* resume the device if needed */
        ret = __platform_pm_runtime_resume(pdev);

        /* the driver has been initialized now, so clear the init flag */
        clear_bit(PDEV_ARCHDATA_FLAG_INIT, &pdev->archdata.flags);

        /* at this point the platform device may be:
         * resumed: ret = 0, flags = 0, clock started
         * failed: ret < 0, FLAG_SUSP set, clock stopped
         */
        mutex_unlock(&ad->mutex);
out:
        dev_dbg(dev, "platform_pm_runtime_resume() [%d] returns %d\n",
                hwblk, ret);

        return ret;
}

int platform_pm_runtime_idle(struct device *dev)
{
        struct platform_device *pdev = to_platform_device(dev);
        int hwblk = pdev->archdata.hwblk_id;
        int ret = 0;

        dev_dbg(dev, "platform_pm_runtime_idle() [%d]\n", hwblk);

        /* ignore off-chip platform devices */
        if (!hwblk)
                goto out;

        /* interrupt context not allowed, use pm_runtime_put()! */
        might_sleep();

        /* suspend synchronously to disable clocks immediately */
        ret = pm_runtime_suspend(dev);
out:
        dev_dbg(dev, "platform_pm_runtime_idle() [%d] done!\n", hwblk);
        return ret;
}

static int platform_bus_notify(struct notifier_block *nb,
                               unsigned long action, void *data)
{
        struct device *dev = data;
        struct platform_device *pdev = to_platform_device(dev);
        int hwblk = pdev->archdata.hwblk_id;

        /* ignore off-chip platform devices */
        if (!hwblk)
                return 0;

        switch (action) {
        case BUS_NOTIFY_ADD_DEVICE:
                INIT_LIST_HEAD(&pdev->archdata.entry);
                mutex_init(&pdev->archdata.mutex);
                /* platform devices without drivers should be disabled */
                hwblk_enable(hwblk_info, hwblk);
                hwblk_disable(hwblk_info, hwblk);
                /* make sure driver re-inits itself once */
                __set_bit(PDEV_ARCHDATA_FLAG_INIT, &pdev->archdata.flags);
                break;
        /* TODO: add BUS_NOTIFY_BIND_DRIVER and increase idle count */
        case BUS_NOTIFY_BOUND_DRIVER:
                /* keep track of number of devices in use per hwblk */
                hwblk_cnt_inc(hwblk_info, hwblk, HWBLK_CNT_DEVICES);
                break;
        case BUS_NOTIFY_UNBOUND_DRIVER:
                /* keep track of number of devices in use per hwblk */
                hwblk_cnt_dec(hwblk_info, hwblk, HWBLK_CNT_DEVICES);
                /* make sure driver re-inits itself once */
                __set_bit(PDEV_ARCHDATA_FLAG_INIT, &pdev->archdata.flags);
                break;
        case BUS_NOTIFY_DEL_DEVICE:
                break;
        }
        return 0;
}

static struct notifier_block platform_bus_notifier = {
        .notifier_call = platform_bus_notify
};

static int __init sh_pm_runtime_init(void)
{
        INIT_WORK(&hwblk_work, platform_pm_runtime_work);

        bus_register_notifier(&platform_bus_type, &platform_bus_notifier);
        return 0;
}
core_initcall(sh_pm_runtime_init);