s3c2410_wdt.c

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/* linux/drivers/char/watchdog/s3c2410_wdt.c
 *
 * Copyright (c) 2004 Simtec Electronics
 *  Ben Dooks <[email protected]>
 *
 * S3C2410 Watchdog Timer Support
 *
 * Based on, softdog.c by Alan Cox,
 *     (c) Copyright 1996 Alan Cox <[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.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program; if not, write to the Free Software
 * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
*/

#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt

#include <linux/module.h>
#include <linux/moduleparam.h>
#include <linux/types.h>
#include <linux/timer.h>
#include <linux/miscdevice.h> /* for MODULE_ALIAS_MISCDEV */
#include <linux/watchdog.h>
#include <linux/init.h>
#include <linux/platform_device.h>
#include <linux/interrupt.h>
#include <linux/clk.h>
#include <linux/uaccess.h>
#include <linux/io.h>
#include <linux/cpufreq.h>
#include <linux/slab.h>
#include <linux/err.h>
#include <linux/of.h>

#include <mach/map.h>

#undef S3C_VA_WATCHDOG
#define S3C_VA_WATCHDOG (0)

#include <plat/regs-watchdog.h>

#define CONFIG_S3C2410_WATCHDOG_ATBOOT      (0)
#define CONFIG_S3C2410_WATCHDOG_DEFAULT_TIME    (15)

static bool nowayout    = WATCHDOG_NOWAYOUT;
static int tmr_margin   = CONFIG_S3C2410_WATCHDOG_DEFAULT_TIME;
static int tmr_atboot   = CONFIG_S3C2410_WATCHDOG_ATBOOT;
static int soft_noboot;
static int debug;

module_param(tmr_margin,  int, 0);
module_param(tmr_atboot,  int, 0);
module_param(nowayout,   bool, 0);
module_param(soft_noboot, int, 0);
module_param(debug,   int, 0);

MODULE_PARM_DESC(tmr_margin, "Watchdog tmr_margin in seconds. (default="
        __MODULE_STRING(CONFIG_S3C2410_WATCHDOG_DEFAULT_TIME) ")");
MODULE_PARM_DESC(tmr_atboot,
        "Watchdog is started at boot time if set to 1, default="
            __MODULE_STRING(CONFIG_S3C2410_WATCHDOG_ATBOOT));
MODULE_PARM_DESC(nowayout, "Watchdog cannot be stopped once started (default="
            __MODULE_STRING(WATCHDOG_NOWAYOUT) ")");
MODULE_PARM_DESC(soft_noboot, "Watchdog action, set to 1 to ignore reboots, "
            "0 to reboot (default 0)");
MODULE_PARM_DESC(debug, "Watchdog debug, set to >1 for debug (default 0)");

static struct device    *wdt_dev;   /* platform device attached to */
static struct resource  *wdt_mem;
static struct resource  *wdt_irq;
static struct clk   *wdt_clock;
static void __iomem *wdt_base;
static unsigned int  wdt_count;
static DEFINE_SPINLOCK(wdt_lock);

/* watchdog control routines */

#define DBG(fmt, ...)                   \
do {                            \
    if (debug)                  \
        pr_info(fmt, ##__VA_ARGS__);        \
} while (0)

/* functions */

static int s3c2410wdt_keepalive(struct watchdog_device *wdd)
{
    spin_lock(&wdt_lock);
    writel(wdt_count, wdt_base + S3C2410_WTCNT);
    spin_unlock(&wdt_lock);

    return 0;
}

static void __s3c2410wdt_stop(void)
{
    unsigned long wtcon;

    wtcon = readl(wdt_base + S3C2410_WTCON);
    wtcon &= ~(S3C2410_WTCON_ENABLE | S3C2410_WTCON_RSTEN);
    writel(wtcon, wdt_base + S3C2410_WTCON);
}

static int s3c2410wdt_stop(struct watchdog_device *wdd)
{
    spin_lock(&wdt_lock);
    __s3c2410wdt_stop();
    spin_unlock(&wdt_lock);

    return 0;
}

static int s3c2410wdt_start(struct watchdog_device *wdd)
{
    unsigned long wtcon;

    spin_lock(&wdt_lock);

    __s3c2410wdt_stop();

    wtcon = readl(wdt_base + S3C2410_WTCON);
    wtcon |= S3C2410_WTCON_ENABLE | S3C2410_WTCON_DIV128;

    if (soft_noboot) {
        wtcon |= S3C2410_WTCON_INTEN;
        wtcon &= ~S3C2410_WTCON_RSTEN;
    } else {
        wtcon &= ~S3C2410_WTCON_INTEN;
        wtcon |= S3C2410_WTCON_RSTEN;
    }

    DBG("%s: wdt_count=0x%08x, wtcon=%08lx\n",
        __func__, wdt_count, wtcon);

    writel(wdt_count, wdt_base + S3C2410_WTDAT);
    writel(wdt_count, wdt_base + S3C2410_WTCNT);
    writel(wtcon, wdt_base + S3C2410_WTCON);
    spin_unlock(&wdt_lock);

    return 0;
}

static inline int s3c2410wdt_is_running(void)
{
    return readl(wdt_base + S3C2410_WTCON) & S3C2410_WTCON_ENABLE;
}

static int s3c2410wdt_set_heartbeat(struct watchdog_device *wdd, unsigned timeout)
{
    unsigned long freq = clk_get_rate(wdt_clock);
    unsigned int count;
    unsigned int divisor = 1;
    unsigned long wtcon;

    if (timeout < 1)
        return -EINVAL;

    freq /= 128;
    count = timeout * freq;

    DBG("%s: count=%d, timeout=%d, freq=%lu\n",
        __func__, count, timeout, freq);

    /* if the count is bigger than the watchdog register,
       then work out what we need to do (and if) we can
       actually make this value
    */

    if (count >= 0x10000) {
        for (divisor = 1; divisor <= 0x100; divisor++) {
            if ((count / divisor) < 0x10000)
                break;
        }

        if ((count / divisor) >= 0x10000) {
            dev_err(wdt_dev, "timeout %d too big\n", timeout);
            return -EINVAL;
        }
    }

    DBG("%s: timeout=%d, divisor=%d, count=%d (%08x)\n",
        __func__, timeout, divisor, count, count/divisor);

    count /= divisor;
    wdt_count = count;

    /* update the pre-scaler */
    wtcon = readl(wdt_base + S3C2410_WTCON);
    wtcon &= ~S3C2410_WTCON_PRESCALE_MASK;
    wtcon |= S3C2410_WTCON_PRESCALE(divisor-1);

    writel(count, wdt_base + S3C2410_WTDAT);
    writel(wtcon, wdt_base + S3C2410_WTCON);

    wdd->timeout = (count * divisor) / freq;

    return 0;
}

#define OPTIONS (WDIOF_SETTIMEOUT | WDIOF_KEEPALIVEPING | WDIOF_MAGICCLOSE)

static const struct watchdog_info s3c2410_wdt_ident = {
    .options          =     OPTIONS,
    .firmware_version = 0,
    .identity         = "S3C2410 Watchdog",
};

static struct watchdog_ops s3c2410wdt_ops = {
    .owner = THIS_MODULE,
    .start = s3c2410wdt_start,
    .stop = s3c2410wdt_stop,
    .ping = s3c2410wdt_keepalive,
    .set_timeout = s3c2410wdt_set_heartbeat,
};

static struct watchdog_device s3c2410_wdd = {
    .info = &s3c2410_wdt_ident,
    .ops = &s3c2410wdt_ops,
};

/* interrupt handler code */

static irqreturn_t s3c2410wdt_irq(int irqno, void *param)
{
    dev_info(wdt_dev, "watchdog timer expired (irq)\n");

    s3c2410wdt_keepalive(&s3c2410_wdd);
    return IRQ_HANDLED;
}


#ifdef CONFIG_CPU_FREQ

static int s3c2410wdt_cpufreq_transition(struct notifier_block *nb,
                      unsigned long val, void *data)
{
    int ret;

    if (!s3c2410wdt_is_running())
        goto done;

    if (val == CPUFREQ_PRECHANGE) {
        /* To ensure that over the change we don't cause the
         * watchdog to trigger, we perform an keep-alive if
         * the watchdog is running.
         */

        s3c2410wdt_keepalive(&s3c2410_wdd);
    } else if (val == CPUFREQ_POSTCHANGE) {
        s3c2410wdt_stop(&s3c2410_wdd);

        ret = s3c2410wdt_set_heartbeat(&s3c2410_wdd, s3c2410_wdd.timeout);

        if (ret >= 0)
            s3c2410wdt_start(&s3c2410_wdd);
        else
            goto err;
    }

done:
    return 0;

 err:
    dev_err(wdt_dev, "cannot set new value for timeout %d\n",
                s3c2410_wdd.timeout);
    return ret;
}

static struct notifier_block s3c2410wdt_cpufreq_transition_nb = {
    .notifier_call  = s3c2410wdt_cpufreq_transition,
};

static inline int s3c2410wdt_cpufreq_register(void)
{
    return cpufreq_register_notifier(&s3c2410wdt_cpufreq_transition_nb,
                     CPUFREQ_TRANSITION_NOTIFIER);
}

static inline void s3c2410wdt_cpufreq_deregister(void)
{
    cpufreq_unregister_notifier(&s3c2410wdt_cpufreq_transition_nb,
                    CPUFREQ_TRANSITION_NOTIFIER);
}

#else
static inline int s3c2410wdt_cpufreq_register(void)
{
    return 0;
}

static inline void s3c2410wdt_cpufreq_deregister(void)
{
}
#endif

static int __devinit s3c2410wdt_probe(struct platform_device *pdev)
{
    struct device *dev;
    unsigned int wtcon;
    int started = 0;
    int ret;
    int size;

    DBG("%s: probe=%p\n", __func__, pdev);

    dev = &pdev->dev;
    wdt_dev = &pdev->dev;

    wdt_mem = platform_get_resource(pdev, IORESOURCE_MEM, 0);
    if (wdt_mem == NULL) {
        dev_err(dev, "no memory resource specified\n");
        return -ENOENT;
    }

    wdt_irq = platform_get_resource(pdev, IORESOURCE_IRQ, 0);
    if (wdt_irq == NULL) {
        dev_err(dev, "no irq resource specified\n");
        ret = -ENOENT;
        goto err;
    }

    /* get the memory region for the watchdog timer */

    size = resource_size(wdt_mem);
    if (!request_mem_region(wdt_mem->start, size, pdev->name)) {
        dev_err(dev, "failed to get memory region\n");
        ret = -EBUSY;
        goto err;
    }

    wdt_base = ioremap(wdt_mem->start, size);
    if (wdt_base == NULL) {
        dev_err(dev, "failed to ioremap() region\n");
        ret = -EINVAL;
        goto err_req;
    }

    DBG("probe: mapped wdt_base=%p\n", wdt_base);

    wdt_clock = clk_get(&pdev->dev, "watchdog");
    if (IS_ERR(wdt_clock)) {
        dev_err(dev, "failed to find watchdog clock source\n");
        ret = PTR_ERR(wdt_clock);
        goto err_map;
    }

    clk_enable(wdt_clock);

    ret = s3c2410wdt_cpufreq_register();
    if (ret < 0) {
        pr_err("failed to register cpufreq\n");
        goto err_clk;
    }

    /* see if we can actually set the requested timer margin, and if
     * not, try the default value */

    if (s3c2410wdt_set_heartbeat(&s3c2410_wdd, tmr_margin)) {
        started = s3c2410wdt_set_heartbeat(&s3c2410_wdd,
                    CONFIG_S3C2410_WATCHDOG_DEFAULT_TIME);

        if (started == 0)
            dev_info(dev,
               "tmr_margin value out of range, default %d used\n",
                   CONFIG_S3C2410_WATCHDOG_DEFAULT_TIME);
        else
            dev_info(dev, "default timer value is out of range, "
                            "cannot start\n");
    }

    ret = request_irq(wdt_irq->start, s3c2410wdt_irq, 0, pdev->name, pdev);
    if (ret != 0) {
        dev_err(dev, "failed to install irq (%d)\n", ret);
        goto err_cpufreq;
    }

    watchdog_set_nowayout(&s3c2410_wdd, nowayout);

    ret = watchdog_register_device(&s3c2410_wdd);
    if (ret) {
        dev_err(dev, "cannot register watchdog (%d)\n", ret);
        goto err_irq;
    }

    if (tmr_atboot && started == 0) {
        dev_info(dev, "starting watchdog timer\n");
        s3c2410wdt_start(&s3c2410_wdd);
    } else if (!tmr_atboot) {
        /* if we're not enabling the watchdog, then ensure it is
         * disabled if it has been left running from the bootloader
         * or other source */

        s3c2410wdt_stop(&s3c2410_wdd);
    }

    /* print out a statement of readiness */

    wtcon = readl(wdt_base + S3C2410_WTCON);

    dev_info(dev, "watchdog %sactive, reset %sabled, irq %sabled\n",
         (wtcon & S3C2410_WTCON_ENABLE) ?  "" : "in",
         (wtcon & S3C2410_WTCON_RSTEN) ? "en" : "dis",
         (wtcon & S3C2410_WTCON_INTEN) ? "en" : "dis");

    return 0;

 err_irq:
    free_irq(wdt_irq->start, pdev);

 err_cpufreq:
    s3c2410wdt_cpufreq_deregister();

 err_clk:
    clk_disable(wdt_clock);
    clk_put(wdt_clock);
    wdt_clock = NULL;

 err_map:
    iounmap(wdt_base);

 err_req:
    release_mem_region(wdt_mem->start, size);

 err:
    wdt_irq = NULL;
    wdt_mem = NULL;
    return ret;
}

static int __devexit s3c2410wdt_remove(struct platform_device *dev)
{
    watchdog_unregister_device(&s3c2410_wdd);

    free_irq(wdt_irq->start, dev);

    s3c2410wdt_cpufreq_deregister();

    clk_disable(wdt_clock);
    clk_put(wdt_clock);
    wdt_clock = NULL;

    iounmap(wdt_base);

    release_mem_region(wdt_mem->start, resource_size(wdt_mem));
    wdt_irq = NULL;
    wdt_mem = NULL;
    return 0;
}

static void s3c2410wdt_shutdown(struct platform_device *dev)
{
    s3c2410wdt_stop(&s3c2410_wdd);
}

#ifdef CONFIG_PM

static unsigned long wtcon_save;
static unsigned long wtdat_save;

static int s3c2410wdt_suspend(struct platform_device *dev, pm_message_t state)
{
    /* Save watchdog state, and turn it off. */
    wtcon_save = readl(wdt_base + S3C2410_WTCON);
    wtdat_save = readl(wdt_base + S3C2410_WTDAT);

    /* Note that WTCNT doesn't need to be saved. */
    s3c2410wdt_stop(&s3c2410_wdd);

    return 0;
}

static int s3c2410wdt_resume(struct platform_device *dev)
{
    /* Restore watchdog state. */

    writel(wtdat_save, wdt_base + S3C2410_WTDAT);
    writel(wtdat_save, wdt_base + S3C2410_WTCNT); /* Reset count */
    writel(wtcon_save, wdt_base + S3C2410_WTCON);

    pr_info("watchdog %sabled\n",
        (wtcon_save & S3C2410_WTCON_ENABLE) ? "en" : "dis");

    return 0;
}

#else
#define s3c2410wdt_suspend NULL
#define s3c2410wdt_resume  NULL
#endif /* CONFIG_PM */

#ifdef CONFIG_OF
static const struct of_device_id s3c2410_wdt_match[] = {
    { .compatible = "samsung,s3c2410-wdt" },
    {},
};
MODULE_DEVICE_TABLE(of, s3c2410_wdt_match);
#endif

static struct platform_driver s3c2410wdt_driver = {
    .probe      = s3c2410wdt_probe,
    .remove     = __devexit_p(s3c2410wdt_remove),
    .shutdown   = s3c2410wdt_shutdown,
    .suspend    = s3c2410wdt_suspend,
    .resume     = s3c2410wdt_resume,
    .driver     = {
        .owner  = THIS_MODULE,
        .name   = "s3c2410-wdt",
        .of_match_table = of_match_ptr(s3c2410_wdt_match),
    },
};

module_platform_driver(s3c2410wdt_driver);

MODULE_AUTHOR("Ben Dooks <[email protected]>, "
          "Dimitry Andric <[email protected]>");
MODULE_DESCRIPTION("S3C2410 Watchdog Device Driver");
MODULE_LICENSE("GPL");
MODULE_ALIAS_MISCDEV(WATCHDOG_MINOR);
MODULE_ALIAS("platform:s3c2410-wdt");