da9052_wdt.c

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/*
 * System monitoring driver for DA9052 PMICs.
 *
 * Copyright(c) 2012 Dialog Semiconductor Ltd.
 *
 * Author: Anthony Olech <[email protected]>
 *
 * 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)
{
    struct da9052_wdt_data *driver_data =
        container_of(r, struct da9052_wdt_data, kref);

    kfree(driver_data);
}

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 __devinit 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;
    }

    dev_set_drvdata(&pdev->dev, driver_data);
err:
    return ret;
}

static int __devexit da9052_wdt_remove(struct platform_device *pdev)
{
    struct da9052_wdt_data *driver_data = dev_get_drvdata(&pdev->dev);

    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 = __devexit_p(da9052_wdt_remove),
    .driver = {
        .name   = "da9052-watchdog",
    },
};

module_platform_driver(da9052_wdt_driver);

MODULE_AUTHOR("Anthony Olech <[email protected]>");
MODULE_DESCRIPTION("DA9052 SM Device Driver");
MODULE_LICENSE("GPL");
MODULE_ALIAS("platform:da9052-watchdog");