wm831x_wdt.c

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/*
 * Watchdog driver for the wm831x PMICs
 *
 * Copyright (C) 2009 Wolfson Microelectronics
 *
 * 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
 */

#include <linux/module.h>
#include <linux/moduleparam.h>
#include <linux/types.h>
#include <linux/kernel.h>
#include <linux/slab.h>
#include <linux/platform_device.h>
#include <linux/watchdog.h>
#include <linux/uaccess.h>
#include <linux/gpio.h>

#include <linux/mfd/wm831x/core.h>
#include <linux/mfd/wm831x/pdata.h>
#include <linux/mfd/wm831x/watchdog.h>

static bool nowayout = WATCHDOG_NOWAYOUT;
module_param(nowayout, bool, 0);
MODULE_PARM_DESC(nowayout,
         "Watchdog cannot be stopped once started (default="
         __MODULE_STRING(WATCHDOG_NOWAYOUT) ")");

struct wm831x_wdt_drvdata {
    struct watchdog_device wdt;
    struct wm831x *wm831x;
    struct mutex lock;
    int update_gpio;
    int update_state;
};

/* We can't use the sub-second values here but they're included
 * for completeness.  */
static struct {
    unsigned int time;  /* Seconds */
    u16 val;            /* WDOG_TO value */
} wm831x_wdt_cfgs[] = {
    {  1, 2 },
    {  2, 3 },
    {  4, 4 },
    {  8, 5 },
    { 16, 6 },
    { 32, 7 },
    { 33, 7 },  /* Actually 32.768s so include both, others round down */
};

static int wm831x_wdt_start(struct watchdog_device *wdt_dev)
{
    struct wm831x_wdt_drvdata *driver_data = watchdog_get_drvdata(wdt_dev);
    struct wm831x *wm831x = driver_data->wm831x;
    int ret;

    mutex_lock(&driver_data->lock);

    ret = wm831x_reg_unlock(wm831x);
    if (ret == 0) {
        ret = wm831x_set_bits(wm831x, WM831X_WATCHDOG,
                      WM831X_WDOG_ENA, WM831X_WDOG_ENA);
        wm831x_reg_lock(wm831x);
    } else {
        dev_err(wm831x->dev, "Failed to unlock security key: %d\n",
            ret);
    }

    mutex_unlock(&driver_data->lock);

    return ret;
}

static int wm831x_wdt_stop(struct watchdog_device *wdt_dev)
{
    struct wm831x_wdt_drvdata *driver_data = watchdog_get_drvdata(wdt_dev);
    struct wm831x *wm831x = driver_data->wm831x;
    int ret;

    mutex_lock(&driver_data->lock);

    ret = wm831x_reg_unlock(wm831x);
    if (ret == 0) {
        ret = wm831x_set_bits(wm831x, WM831X_WATCHDOG,
                      WM831X_WDOG_ENA, 0);
        wm831x_reg_lock(wm831x);
    } else {
        dev_err(wm831x->dev, "Failed to unlock security key: %d\n",
            ret);
    }

    mutex_unlock(&driver_data->lock);

    return ret;
}

static int wm831x_wdt_ping(struct watchdog_device *wdt_dev)
{
    struct wm831x_wdt_drvdata *driver_data = watchdog_get_drvdata(wdt_dev);
    struct wm831x *wm831x = driver_data->wm831x;
    int ret;
    u16 reg;

    mutex_lock(&driver_data->lock);

    if (driver_data->update_gpio) {
        gpio_set_value_cansleep(driver_data->update_gpio,
                    driver_data->update_state);
        driver_data->update_state = !driver_data->update_state;
        ret = 0;
        goto out;
    }

    reg = wm831x_reg_read(wm831x, WM831X_WATCHDOG);

    if (!(reg & WM831X_WDOG_RST_SRC)) {
        dev_err(wm831x->dev, "Hardware watchdog update unsupported\n");
        ret = -EINVAL;
        goto out;
    }

    reg |= WM831X_WDOG_RESET;

    ret = wm831x_reg_unlock(wm831x);
    if (ret == 0) {
        ret = wm831x_reg_write(wm831x, WM831X_WATCHDOG, reg);
        wm831x_reg_lock(wm831x);
    } else {
        dev_err(wm831x->dev, "Failed to unlock security key: %d\n",
            ret);
    }

out:
    mutex_unlock(&driver_data->lock);

    return ret;
}

static int wm831x_wdt_set_timeout(struct watchdog_device *wdt_dev,
                  unsigned int timeout)
{
    struct wm831x_wdt_drvdata *driver_data = watchdog_get_drvdata(wdt_dev);
    struct wm831x *wm831x = driver_data->wm831x;
    int ret, i;

    for (i = 0; i < ARRAY_SIZE(wm831x_wdt_cfgs); i++)
        if (wm831x_wdt_cfgs[i].time == timeout)
            break;
    if (i == ARRAY_SIZE(wm831x_wdt_cfgs))
        return -EINVAL;

    ret = wm831x_reg_unlock(wm831x);
    if (ret == 0) {
        ret = wm831x_set_bits(wm831x, WM831X_WATCHDOG,
                      WM831X_WDOG_TO_MASK,
                      wm831x_wdt_cfgs[i].val);
        wm831x_reg_lock(wm831x);
    } else {
        dev_err(wm831x->dev, "Failed to unlock security key: %d\n",
            ret);
    }

    wdt_dev->timeout = timeout;

    return ret;
}

static const struct watchdog_info wm831x_wdt_info = {
    .options = WDIOF_SETTIMEOUT | WDIOF_KEEPALIVEPING | WDIOF_MAGICCLOSE,
    .identity = "WM831x Watchdog",
};

static const struct watchdog_ops wm831x_wdt_ops = {
    .owner = THIS_MODULE,
    .start = wm831x_wdt_start,
    .stop = wm831x_wdt_stop,
    .ping = wm831x_wdt_ping,
    .set_timeout = wm831x_wdt_set_timeout,
};

static int __devinit wm831x_wdt_probe(struct platform_device *pdev)
{
    struct wm831x *wm831x = dev_get_drvdata(pdev->dev.parent);
    struct wm831x_pdata *chip_pdata;
    struct wm831x_watchdog_pdata *pdata;
    struct wm831x_wdt_drvdata *driver_data;
    struct watchdog_device *wm831x_wdt;
    int reg, ret, i;

    ret = wm831x_reg_read(wm831x, WM831X_WATCHDOG);
    if (ret < 0) {
        dev_err(wm831x->dev, "Failed to read watchdog status: %d\n",
            ret);
        goto err;
    }
    reg = ret;

    if (reg & WM831X_WDOG_DEBUG)
        dev_warn(wm831x->dev, "Watchdog is paused\n");

    driver_data = devm_kzalloc(&pdev->dev, sizeof(*driver_data),
                   GFP_KERNEL);
    if (!driver_data) {
        dev_err(wm831x->dev, "Unable to alloacate watchdog device\n");
        ret = -ENOMEM;
        goto err;
    }

    mutex_init(&driver_data->lock);
    driver_data->wm831x = wm831x;

    wm831x_wdt = &driver_data->wdt;

    wm831x_wdt->info = &wm831x_wdt_info;
    wm831x_wdt->ops = &wm831x_wdt_ops;
    watchdog_set_nowayout(wm831x_wdt, nowayout);
    watchdog_set_drvdata(wm831x_wdt, driver_data);

    reg = wm831x_reg_read(wm831x, WM831X_WATCHDOG);
    reg &= WM831X_WDOG_TO_MASK;
    for (i = 0; i < ARRAY_SIZE(wm831x_wdt_cfgs); i++)
        if (wm831x_wdt_cfgs[i].val == reg)
            break;
    if (i == ARRAY_SIZE(wm831x_wdt_cfgs))
        dev_warn(wm831x->dev,
             "Unknown watchdog timeout: %x\n", reg);
    else
        wm831x_wdt->timeout = wm831x_wdt_cfgs[i].time;

    /* Apply any configuration */
    if (pdev->dev.parent->platform_data) {
        chip_pdata = pdev->dev.parent->platform_data;
        pdata = chip_pdata->watchdog;
    } else {
        pdata = NULL;
    }

    if (pdata) {
        reg &= ~(WM831X_WDOG_SECACT_MASK | WM831X_WDOG_PRIMACT_MASK |
             WM831X_WDOG_RST_SRC);

        reg |= pdata->primary << WM831X_WDOG_PRIMACT_SHIFT;
        reg |= pdata->secondary << WM831X_WDOG_SECACT_SHIFT;
        reg |= pdata->software << WM831X_WDOG_RST_SRC_SHIFT;

        if (pdata->update_gpio) {
            ret = gpio_request_one(pdata->update_gpio,
                           GPIOF_DIR_OUT | GPIOF_INIT_LOW,
                           "Watchdog update");
            if (ret < 0) {
                dev_err(wm831x->dev,
                    "Failed to request update GPIO: %d\n",
                    ret);
                goto err;
            }

            driver_data->update_gpio = pdata->update_gpio;

            /* Make sure the watchdog takes hardware updates */
            reg |= WM831X_WDOG_RST_SRC;
        }

        ret = wm831x_reg_unlock(wm831x);
        if (ret == 0) {
            ret = wm831x_reg_write(wm831x, WM831X_WATCHDOG, reg);
            wm831x_reg_lock(wm831x);
        } else {
            dev_err(wm831x->dev,
                "Failed to unlock security key: %d\n", ret);
            goto err_gpio;
        }
    }

    ret = watchdog_register_device(&driver_data->wdt);
    if (ret != 0) {
        dev_err(wm831x->dev, "watchdog_register_device() failed: %d\n",
            ret);
        goto err_gpio;
    }

    dev_set_drvdata(&pdev->dev, driver_data);

    return 0;

err_gpio:
    if (driver_data->update_gpio)
        gpio_free(driver_data->update_gpio);
err:
    return ret;
}

static int __devexit wm831x_wdt_remove(struct platform_device *pdev)
{
    struct wm831x_wdt_drvdata *driver_data = dev_get_drvdata(&pdev->dev);

    watchdog_unregister_device(&driver_data->wdt);

    if (driver_data->update_gpio)
        gpio_free(driver_data->update_gpio);

    return 0;
}

static struct platform_driver wm831x_wdt_driver = {
    .probe = wm831x_wdt_probe,
    .remove = __devexit_p(wm831x_wdt_remove),
    .driver = {
        .name = "wm831x-watchdog",
    },
};

module_platform_driver(wm831x_wdt_driver);

MODULE_AUTHOR("Mark Brown");
MODULE_DESCRIPTION("WM831x Watchdog");
MODULE_LICENSE("GPL");
MODULE_ALIAS("platform:wm831x-watchdog");