/*
 * System monitoring driver for DA9052 PMICs.
 *
 * Copyright(c) 2012 Dialog Semiconductor Ltd.
 *
 * Author: Anthony Olech <Anthony.Olech@diasemi.com>
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation; either version 2 of the License, or
 * (at your option) any later version.
 *
 */

#include <linux/module.h>
#include <linux/delay.h>
#include <linux/uaccess.h>
#include <linux/platform_device.h>
#include <linux/time.h>
#include <linux/watchdog.h>
#include <linux/types.h>
#include <linux/kernel.h>
#include <linux/jiffies.h>

#include <linux/mfd/da9052/reg.h>
#include <linux/mfd/da9052/da9052.h>

#define DA9052_DEF_TIMEOUT      4
#define DA9052_TWDMIN           256

struct da9052_wdt_data {
        struct watchdog_device wdt;
        struct da9052 *da9052;
        struct kref kref;
        unsigned long jpast;
};

static const struct {
        u8 reg_val;
        int time;  /* Seconds */
} da9052_wdt_maps[] = {
        { 1, 2 },
        { 2, 4 },
        { 3, 8 },
        { 4, 16 },
        { 5, 32 },
        { 5, 33 },  /* Actual time  32.768s so included both 32s and 33s */
        { 6, 65 },
        { 6, 66 },  /* Actual time 65.536s so include both, 65s and 66s */
        { 7, 131 },
};


static void da9052_wdt_release_resources(struct kref *r)
{
}

static int da9052_wdt_set_timeout(struct watchdog_device *wdt_dev,
                                  unsigned int timeout)
{
        struct da9052_wdt_data *driver_data = watchdog_get_drvdata(wdt_dev);
        struct da9052 *da9052 = driver_data->da9052;
        int ret, i;

        /*
         * Disable the Watchdog timer before setting
         * new time out.
         */
        ret = da9052_reg_update(da9052, DA9052_CONTROL_D_REG,
                                DA9052_CONTROLD_TWDSCALE, 0);
        if (ret < 0) {
                dev_err(da9052->dev, "Failed to disable watchdog bit, %d\n",
                        ret);
                return ret;
        }
        if (timeout) {
                /*
                 * To change the timeout, da9052 needs to
                 * be disabled for at least 150 us.
                 */
                udelay(150);

                /* Set the desired timeout */
                for (i = 0; i < ARRAY_SIZE(da9052_wdt_maps); i++)
                        if (da9052_wdt_maps[i].time == timeout)
                                break;

                if (i == ARRAY_SIZE(da9052_wdt_maps))
                        ret = -EINVAL;
                else
                        ret = da9052_reg_update(da9052, DA9052_CONTROL_D_REG,
                                                DA9052_CONTROLD_TWDSCALE,
                                                da9052_wdt_maps[i].reg_val);
                if (ret < 0) {
                        dev_err(da9052->dev,
                                "Failed to update timescale bit, %d\n", ret);
                        return ret;
                }

                wdt_dev->timeout = timeout;
                driver_data->jpast = jiffies;
        }

        return 0;
}

static void da9052_wdt_ref(struct watchdog_device *wdt_dev)
{
        struct da9052_wdt_data *driver_data = watchdog_get_drvdata(wdt_dev);

        kref_get(&driver_data->kref);
}

static void da9052_wdt_unref(struct watchdog_device *wdt_dev)
{
        struct da9052_wdt_data *driver_data = watchdog_get_drvdata(wdt_dev);

        kref_put(&driver_data->kref, da9052_wdt_release_resources);
}

static int da9052_wdt_start(struct watchdog_device *wdt_dev)
{
        return da9052_wdt_set_timeout(wdt_dev, wdt_dev->timeout);
}

static int da9052_wdt_stop(struct watchdog_device *wdt_dev)
{
        return da9052_wdt_set_timeout(wdt_dev, 0);
}

static int da9052_wdt_ping(struct watchdog_device *wdt_dev)
{
        struct da9052_wdt_data *driver_data = watchdog_get_drvdata(wdt_dev);
        struct da9052 *da9052 = driver_data->da9052;
        unsigned long msec, jnow = jiffies;
        int ret;

        /*
         * We have a minimum time for watchdog window called TWDMIN. A write
         * to the watchdog before this elapsed time should cause an error.
         */
        msec = (jnow - driver_data->jpast) * 1000/HZ;
        if (msec < DA9052_TWDMIN)
                mdelay(msec);

        /* Reset the watchdog timer */
        ret = da9052_reg_update(da9052, DA9052_CONTROL_D_REG,
                                DA9052_CONTROLD_WATCHDOG, 1 << 7);
        if (ret < 0)
                goto err_strobe;

        /*
         * FIXME: Reset the watchdog core, in general PMIC
         * is supposed to do this
         */
        ret = da9052_reg_update(da9052, DA9052_CONTROL_D_REG,
                                DA9052_CONTROLD_WATCHDOG, 0 << 7);
err_strobe:
        return ret;
}

static struct watchdog_info da9052_wdt_info = {
        .options        = WDIOF_SETTIMEOUT | WDIOF_KEEPALIVEPING,
        .identity       = "DA9052 Watchdog",
};

static const struct watchdog_ops da9052_wdt_ops = {
        .owner = THIS_MODULE,
        .start = da9052_wdt_start,
        .stop = da9052_wdt_stop,
        .ping = da9052_wdt_ping,
        .set_timeout = da9052_wdt_set_timeout,
        .ref = da9052_wdt_ref,
        .unref = da9052_wdt_unref,
};


static int da9052_wdt_probe(struct platform_device *pdev)
{
        struct da9052 *da9052 = dev_get_drvdata(pdev->dev.parent);
        struct da9052_wdt_data *driver_data;
        struct watchdog_device *da9052_wdt;
        int ret;

        driver_data = devm_kzalloc(&pdev->dev, sizeof(*driver_data),
                                   GFP_KERNEL);
        if (!driver_data) {
                dev_err(da9052->dev, "Unable to alloacate watchdog device\n");
                ret = -ENOMEM;
                goto err;
        }
        driver_data->da9052 = da9052;

        da9052_wdt = &driver_data->wdt;

        da9052_wdt->timeout = DA9052_DEF_TIMEOUT;
        da9052_wdt->info = &da9052_wdt_info;
        da9052_wdt->ops = &da9052_wdt_ops;
        watchdog_set_drvdata(da9052_wdt, driver_data);

        kref_init(&driver_data->kref);

        ret = da9052_reg_update(da9052, DA9052_CONTROL_D_REG,
                                DA9052_CONTROLD_TWDSCALE, 0);
        if (ret < 0) {
                dev_err(&pdev->dev, "Failed to disable watchdog bits, %d\n",
                        ret);
                goto err;
        }

        ret = watchdog_register_device(&driver_data->wdt);
        if (ret != 0) {
                dev_err(da9052->dev, "watchdog_register_device() failed: %d\n",
                        ret);
                goto err;
        }

        platform_set_drvdata(pdev, driver_data);
err:
        return ret;
}

static int da9052_wdt_remove(struct platform_device *pdev)
{
        struct da9052_wdt_data *driver_data = platform_get_drvdata(pdev);

        watchdog_unregister_device(&driver_data->wdt);
        kref_put(&driver_data->kref, da9052_wdt_release_resources);

        return 0;
}

static struct platform_driver da9052_wdt_driver = {
        .probe = da9052_wdt_probe,
        .remove = da9052_wdt_remove,
        .driver = {
                .name   = "da9052-watchdog",
        },
};

module_platform_driver(da9052_wdt_driver);

MODULE_AUTHOR("Anthony Olech <Anthony.Olech@diasemi.com>");
MODULE_DESCRIPTION("DA9052 SM Device Driver");
MODULE_LICENSE("GPL");
MODULE_ALIAS("platform:da9052-watchdog");