omap_wdt.c

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/*
 * omap_wdt.c
 *
 * Watchdog driver for the TI OMAP 16xx & 24xx/34xx 32KHz (non-secure) watchdog
 *
 * Author: MontaVista Software, Inc.
 *   <[email protected]> or <[email protected]>
 *
 * 2003 (c) MontaVista Software, Inc. 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.
 *
 * History:
 *
 * 20030527: George G. Davis <[email protected]>
 *  Initially based on linux-2.4.19-rmk7-pxa1/drivers/char/sa1100_wdt.c
 *  (c) Copyright 2000 Oleg Drokin <[email protected]>
 *  Based on SoftDog driver by Alan Cox <[email protected]>
 *
 * Copyright (c) 2004 Texas Instruments.
 *  1. Modified to support OMAP1610 32-KHz watchdog timer
 *  2. Ported to 2.6 kernel
 *
 * Copyright (c) 2005 David Brownell
 *  Use the driver model and standard identifiers; handle bigger timeouts.
 */

#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt

#include <linux/module.h>
#include <linux/types.h>
#include <linux/kernel.h>
#include <linux/fs.h>
#include <linux/mm.h>
#include <linux/miscdevice.h>
#include <linux/watchdog.h>
#include <linux/reboot.h>
#include <linux/init.h>
#include <linux/err.h>
#include <linux/platform_device.h>
#include <linux/moduleparam.h>
#include <linux/bitops.h>
#include <linux/io.h>
#include <linux/uaccess.h>
#include <linux/slab.h>
#include <linux/pm_runtime.h>
#include <mach/hardware.h>
#include <plat/cpu.h>
#include <plat/prcm.h>

#include "omap_wdt.h"

static struct platform_device *omap_wdt_dev;

static unsigned timer_margin;
module_param(timer_margin, uint, 0);
MODULE_PARM_DESC(timer_margin, "initial watchdog timeout (in seconds)");

static unsigned int wdt_trgr_pattern = 0x1234;
static DEFINE_SPINLOCK(wdt_lock);

struct omap_wdt_dev {
    void __iomem    *base;          /* physical */
    struct device   *dev;
    int             omap_wdt_users;
    struct resource *mem;
    struct miscdevice omap_wdt_miscdev;
};

static void omap_wdt_ping(struct omap_wdt_dev *wdev)
{
    void __iomem    *base = wdev->base;

    /* wait for posted write to complete */
    while ((__raw_readl(base + OMAP_WATCHDOG_WPS)) & 0x08)
        cpu_relax();

    wdt_trgr_pattern = ~wdt_trgr_pattern;
    __raw_writel(wdt_trgr_pattern, (base + OMAP_WATCHDOG_TGR));

    /* wait for posted write to complete */
    while ((__raw_readl(base + OMAP_WATCHDOG_WPS)) & 0x08)
        cpu_relax();
    /* reloaded WCRR from WLDR */
}

static void omap_wdt_enable(struct omap_wdt_dev *wdev)
{
    void __iomem *base = wdev->base;

    /* Sequence to enable the watchdog */
    __raw_writel(0xBBBB, base + OMAP_WATCHDOG_SPR);
    while ((__raw_readl(base + OMAP_WATCHDOG_WPS)) & 0x10)
        cpu_relax();

    __raw_writel(0x4444, base + OMAP_WATCHDOG_SPR);
    while ((__raw_readl(base + OMAP_WATCHDOG_WPS)) & 0x10)
        cpu_relax();
}

static void omap_wdt_disable(struct omap_wdt_dev *wdev)
{
    void __iomem *base = wdev->base;

    /* sequence required to disable watchdog */
    __raw_writel(0xAAAA, base + OMAP_WATCHDOG_SPR); /* TIMER_MODE */
    while (__raw_readl(base + OMAP_WATCHDOG_WPS) & 0x10)
        cpu_relax();

    __raw_writel(0x5555, base + OMAP_WATCHDOG_SPR); /* TIMER_MODE */
    while (__raw_readl(base + OMAP_WATCHDOG_WPS) & 0x10)
        cpu_relax();
}

static void omap_wdt_adjust_timeout(unsigned new_timeout)
{
    if (new_timeout < TIMER_MARGIN_MIN)
        new_timeout = TIMER_MARGIN_DEFAULT;
    if (new_timeout > TIMER_MARGIN_MAX)
        new_timeout = TIMER_MARGIN_MAX;
    timer_margin = new_timeout;
}

static void omap_wdt_set_timeout(struct omap_wdt_dev *wdev)
{
    u32 pre_margin = GET_WLDR_VAL(timer_margin);
    void __iomem *base = wdev->base;

    /* just count up at 32 KHz */
    while (__raw_readl(base + OMAP_WATCHDOG_WPS) & 0x04)
        cpu_relax();

    __raw_writel(pre_margin, base + OMAP_WATCHDOG_LDR);
    while (__raw_readl(base + OMAP_WATCHDOG_WPS) & 0x04)
        cpu_relax();
}

/*
 *  Allow only one task to hold it open
 */
static int omap_wdt_open(struct inode *inode, struct file *file)
{
    struct omap_wdt_dev *wdev = platform_get_drvdata(omap_wdt_dev);
    void __iomem *base = wdev->base;

    if (test_and_set_bit(1, (unsigned long *)&(wdev->omap_wdt_users)))
        return -EBUSY;

    pm_runtime_get_sync(wdev->dev);

    /* initialize prescaler */
    while (__raw_readl(base + OMAP_WATCHDOG_WPS) & 0x01)
        cpu_relax();

    __raw_writel((1 << 5) | (PTV << 2), base + OMAP_WATCHDOG_CNTRL);
    while (__raw_readl(base + OMAP_WATCHDOG_WPS) & 0x01)
        cpu_relax();

    file->private_data = (void *) wdev;

    omap_wdt_set_timeout(wdev);
    omap_wdt_ping(wdev); /* trigger loading of new timeout value */
    omap_wdt_enable(wdev);

    return nonseekable_open(inode, file);
}

static int omap_wdt_release(struct inode *inode, struct file *file)
{
    struct omap_wdt_dev *wdev = file->private_data;

    /*
     *      Shut off the timer unless NOWAYOUT is defined.
     */
#ifndef CONFIG_WATCHDOG_NOWAYOUT
    omap_wdt_disable(wdev);

    pm_runtime_put_sync(wdev->dev);
#else
    pr_crit("Unexpected close, not stopping!\n");
#endif
    wdev->omap_wdt_users = 0;

    return 0;
}

static ssize_t omap_wdt_write(struct file *file, const char __user *data,
        size_t len, loff_t *ppos)
{
    struct omap_wdt_dev *wdev = file->private_data;

    /* Refresh LOAD_TIME. */
    if (len) {
        spin_lock(&wdt_lock);
        omap_wdt_ping(wdev);
        spin_unlock(&wdt_lock);
    }
    return len;
}

static long omap_wdt_ioctl(struct file *file, unsigned int cmd,
                        unsigned long arg)
{
    struct omap_wdt_dev *wdev;
    int new_margin;
    static const struct watchdog_info ident = {
        .identity = "OMAP Watchdog",
        .options = WDIOF_SETTIMEOUT,
        .firmware_version = 0,
    };

    wdev = file->private_data;

    switch (cmd) {
    case WDIOC_GETSUPPORT:
        return copy_to_user((struct watchdog_info __user *)arg, &ident,
                sizeof(ident));
    case WDIOC_GETSTATUS:
        return put_user(0, (int __user *)arg);
    case WDIOC_GETBOOTSTATUS:
#ifdef CONFIG_ARCH_OMAP1
        if (cpu_is_omap16xx())
            return put_user(__raw_readw(ARM_SYSST),
                    (int __user *)arg);
#endif
#ifdef CONFIG_ARCH_OMAP2PLUS
        if (cpu_is_omap24xx())
            return put_user(omap_prcm_get_reset_sources(),
                    (int __user *)arg);
#endif
        return put_user(0, (int __user *)arg);
    case WDIOC_KEEPALIVE:
        spin_lock(&wdt_lock);
        omap_wdt_ping(wdev);
        spin_unlock(&wdt_lock);
        return 0;
    case WDIOC_SETTIMEOUT:
        if (get_user(new_margin, (int __user *)arg))
            return -EFAULT;
        omap_wdt_adjust_timeout(new_margin);

        spin_lock(&wdt_lock);
        omap_wdt_disable(wdev);
        omap_wdt_set_timeout(wdev);
        omap_wdt_enable(wdev);

        omap_wdt_ping(wdev);
        spin_unlock(&wdt_lock);
        /* Fall */
    case WDIOC_GETTIMEOUT:
        return put_user(timer_margin, (int __user *)arg);
    default:
        return -ENOTTY;
    }
}

static const struct file_operations omap_wdt_fops = {
    .owner = THIS_MODULE,
    .write = omap_wdt_write,
    .unlocked_ioctl = omap_wdt_ioctl,
    .open = omap_wdt_open,
    .release = omap_wdt_release,
    .llseek = no_llseek,
};

static int __devinit omap_wdt_probe(struct platform_device *pdev)
{
    struct resource *res, *mem;
    struct omap_wdt_dev *wdev;
    int ret;

    /* reserve static register mappings */
    res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
    if (!res) {
        ret = -ENOENT;
        goto err_get_resource;
    }

    if (omap_wdt_dev) {
        ret = -EBUSY;
        goto err_busy;
    }

    mem = request_mem_region(res->start, resource_size(res), pdev->name);
    if (!mem) {
        ret = -EBUSY;
        goto err_busy;
    }

    wdev = kzalloc(sizeof(struct omap_wdt_dev), GFP_KERNEL);
    if (!wdev) {
        ret = -ENOMEM;
        goto err_kzalloc;
    }

    wdev->omap_wdt_users = 0;
    wdev->mem = mem;
    wdev->dev = &pdev->dev;

    wdev->base = ioremap(res->start, resource_size(res));
    if (!wdev->base) {
        ret = -ENOMEM;
        goto err_ioremap;
    }

    platform_set_drvdata(pdev, wdev);

    pm_runtime_enable(wdev->dev);
    pm_runtime_get_sync(wdev->dev);

    omap_wdt_disable(wdev);
    omap_wdt_adjust_timeout(timer_margin);

    wdev->omap_wdt_miscdev.parent = &pdev->dev;
    wdev->omap_wdt_miscdev.minor = WATCHDOG_MINOR;
    wdev->omap_wdt_miscdev.name = "watchdog";
    wdev->omap_wdt_miscdev.fops = &omap_wdt_fops;

    ret = misc_register(&(wdev->omap_wdt_miscdev));
    if (ret)
        goto err_misc;

    pr_info("OMAP Watchdog Timer Rev 0x%02x: initial timeout %d sec\n",
        __raw_readl(wdev->base + OMAP_WATCHDOG_REV) & 0xFF,
        timer_margin);

    pm_runtime_put_sync(wdev->dev);

    omap_wdt_dev = pdev;

    return 0;

err_misc:
    pm_runtime_disable(wdev->dev);
    platform_set_drvdata(pdev, NULL);
    iounmap(wdev->base);

err_ioremap:
    wdev->base = NULL;
    kfree(wdev);

err_kzalloc:
    release_mem_region(res->start, resource_size(res));

err_busy:
err_get_resource:

    return ret;
}

static void omap_wdt_shutdown(struct platform_device *pdev)
{
    struct omap_wdt_dev *wdev = platform_get_drvdata(pdev);

    if (wdev->omap_wdt_users) {
        omap_wdt_disable(wdev);
        pm_runtime_put_sync(wdev->dev);
    }
}

static int __devexit omap_wdt_remove(struct platform_device *pdev)
{
    struct omap_wdt_dev *wdev = platform_get_drvdata(pdev);
    struct resource *res = platform_get_resource(pdev, IORESOURCE_MEM, 0);

    pm_runtime_disable(wdev->dev);
    if (!res)
        return -ENOENT;

    misc_deregister(&(wdev->omap_wdt_miscdev));
    release_mem_region(res->start, resource_size(res));
    platform_set_drvdata(pdev, NULL);

    iounmap(wdev->base);

    kfree(wdev);
    omap_wdt_dev = NULL;

    return 0;
}

#ifdef  CONFIG_PM

/* REVISIT ... not clear this is the best way to handle system suspend; and
 * it's very inappropriate for selective device suspend (e.g. suspending this
 * through sysfs rather than by stopping the watchdog daemon).  Also, this
 * may not play well enough with NOWAYOUT...
 */

static int omap_wdt_suspend(struct platform_device *pdev, pm_message_t state)
{
    struct omap_wdt_dev *wdev = platform_get_drvdata(pdev);

    if (wdev->omap_wdt_users) {
        omap_wdt_disable(wdev);
        pm_runtime_put_sync(wdev->dev);
    }

    return 0;
}

static int omap_wdt_resume(struct platform_device *pdev)
{
    struct omap_wdt_dev *wdev = platform_get_drvdata(pdev);

    if (wdev->omap_wdt_users) {
        pm_runtime_get_sync(wdev->dev);
        omap_wdt_enable(wdev);
        omap_wdt_ping(wdev);
    }

    return 0;
}

#else
#define omap_wdt_suspend    NULL
#define omap_wdt_resume     NULL
#endif

static const struct of_device_id omap_wdt_of_match[] = {
    { .compatible = "ti,omap3-wdt", },
    {},
};
MODULE_DEVICE_TABLE(of, omap_wdt_of_match);

static struct platform_driver omap_wdt_driver = {
    .probe      = omap_wdt_probe,
    .remove     = __devexit_p(omap_wdt_remove),
    .shutdown   = omap_wdt_shutdown,
    .suspend    = omap_wdt_suspend,
    .resume     = omap_wdt_resume,
    .driver     = {
        .owner  = THIS_MODULE,
        .name   = "omap_wdt",
        .of_match_table = omap_wdt_of_match,
    },
};

module_platform_driver(omap_wdt_driver);

MODULE_AUTHOR("George G. Davis");
MODULE_LICENSE("GPL");
MODULE_ALIAS_MISCDEV(WATCHDOG_MINOR);
MODULE_ALIAS("platform:omap_wdt");