ep93xx_wdt.c

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/*
 * Watchdog driver for Cirrus Logic EP93xx family of devices.
 *
 * Copyright (c) 2004 Ray Lehtiniemi
 * Copyright (c) 2006 Tower Technologies
 * Based on ep93xx driver, bits from alim7101_wdt.c
 *
 * Authors: Ray Lehtiniemi <[email protected]>,
 *  Alessandro Zummo <[email protected]>
 *
 * Copyright (c) 2012 H Hartley Sweeten <[email protected]>
 *  Convert to a platform device and use the watchdog framework API
 *
 * This file is licensed under the terms of the GNU General Public
 * License version 2. This program is licensed "as is" without any
 * warranty of any kind, whether express or implied.
 *
 * This watchdog fires after 250msec, which is a too short interval
 * for us to rely on the user space daemon alone. So we ping the
 * wdt each ~200msec and eventually stop doing it if the user space
 * daemon dies.
 *
 * TODO:
 *
 *  - Test last reset from watchdog status
 *  - Add a few missing ioctls
 */

#include <linux/platform_device.h>
#include <linux/module.h>
#include <linux/miscdevice.h>
#include <linux/watchdog.h>
#include <linux/timer.h>
#include <linux/io.h>

#define WDT_VERSION "0.4"

/* default timeout (secs) */
#define WDT_TIMEOUT 30

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

static unsigned int timeout = WDT_TIMEOUT;
module_param(timeout, uint, 0);
MODULE_PARM_DESC(timeout,
    "Watchdog timeout in seconds. (1<=timeout<=3600, default="
                __MODULE_STRING(WDT_TIMEOUT) ")");

static void __iomem *mmio_base;
static struct timer_list timer;
static unsigned long next_heartbeat;

#define EP93XX_WATCHDOG     0x00
#define EP93XX_WDSTATUS     0x04

/* reset the wdt every ~200ms - the heartbeat of the device is 0.250 seconds*/
#define WDT_INTERVAL (HZ/5)

static void ep93xx_wdt_timer_ping(unsigned long data)
{
    if (time_before(jiffies, next_heartbeat))
        writel(0x5555, mmio_base + EP93XX_WATCHDOG);

    /* Re-set the timer interval */
    mod_timer(&timer, jiffies + WDT_INTERVAL);
}

static int ep93xx_wdt_start(struct watchdog_device *wdd)
{
    next_heartbeat = jiffies + (timeout * HZ);

    writel(0xaaaa, mmio_base + EP93XX_WATCHDOG);
    mod_timer(&timer, jiffies + WDT_INTERVAL);

    return 0;
}

static int ep93xx_wdt_stop(struct watchdog_device *wdd)
{
    del_timer_sync(&timer);
    writel(0xaa55, mmio_base + EP93XX_WATCHDOG);

    return 0;
}

static int ep93xx_wdt_keepalive(struct watchdog_device *wdd)
{
    /* user land ping */
    next_heartbeat = jiffies + (timeout * HZ);

    return 0;
}

static const struct watchdog_info ep93xx_wdt_ident = {
    .options    = WDIOF_CARDRESET |
              WDIOF_MAGICCLOSE |
              WDIOF_KEEPALIVEPING,
    .identity   = "EP93xx Watchdog",
};

static struct watchdog_ops ep93xx_wdt_ops = {
    .owner      = THIS_MODULE,
    .start      = ep93xx_wdt_start,
    .stop       = ep93xx_wdt_stop,
    .ping       = ep93xx_wdt_keepalive,
};

static struct watchdog_device ep93xx_wdt_wdd = {
    .info       = &ep93xx_wdt_ident,
    .ops        = &ep93xx_wdt_ops,
};

static int __devinit ep93xx_wdt_probe(struct platform_device *pdev)
{
    struct resource *res;
    unsigned long val;
    int err;

    res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
    if (!res)
        return -ENXIO;

    if (!devm_request_mem_region(&pdev->dev, res->start,
                     resource_size(res), pdev->name))
        return -EBUSY;

    mmio_base = devm_ioremap(&pdev->dev, res->start, resource_size(res));
    if (!mmio_base)
        return -ENXIO;

    if (timeout < 1 || timeout > 3600) {
        timeout = WDT_TIMEOUT;
        dev_warn(&pdev->dev,
            "timeout value must be 1<=x<=3600, using %d\n",
            timeout);
    }

    val = readl(mmio_base + EP93XX_WATCHDOG);
    ep93xx_wdt_wdd.bootstatus = (val & 0x01) ? WDIOF_CARDRESET : 0;
    ep93xx_wdt_wdd.timeout = timeout;

    watchdog_set_nowayout(&ep93xx_wdt_wdd, nowayout);

    setup_timer(&timer, ep93xx_wdt_timer_ping, 1);

    err = watchdog_register_device(&ep93xx_wdt_wdd);
    if (err)
        return err;

    dev_info(&pdev->dev,
        "EP93XX watchdog, driver version " WDT_VERSION "%s\n",
        (val & 0x08) ? " (nCS1 disable detected)" : "");

    return 0;
}

static int __devexit ep93xx_wdt_remove(struct platform_device *pdev)
{
    watchdog_unregister_device(&ep93xx_wdt_wdd);
    return 0;
}

static struct platform_driver ep93xx_wdt_driver = {
    .driver     = {
        .owner  = THIS_MODULE,
        .name   = "ep93xx-wdt",
    },
    .probe      = ep93xx_wdt_probe,
    .remove     = __devexit_p(ep93xx_wdt_remove),
};

module_platform_driver(ep93xx_wdt_driver);

MODULE_AUTHOR("Ray Lehtiniemi <[email protected]>,"
        "Alessandro Zummo <[email protected]>,"
        "H Hartley Sweeten <[email protected]>");
MODULE_DESCRIPTION("EP93xx Watchdog");
MODULE_LICENSE("GPL");
MODULE_VERSION(WDT_VERSION);
MODULE_ALIAS_MISCDEV(WATCHDOG_MINOR);