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/* linux/drivers/char/watchdog/s3c2410_wdt.c

 *

 * Copyright (c) 2004 Simtec Electronics

 *      Ben Dooks <ben@simtec.co.uk>

 *

 * S3C2410 Watchdog Timer Support

 *

 * Based on, softdog.c by Alan Cox,

 *     (c) Copyright 1996 Alan Cox <alan@redhat.com>

 *

 * 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

 *

 * Changelog:

 *      05-Oct-2004     BJD     Added semaphore init to stop crashes on open

 *                              Fixed tmr_count / wdt_count confusion

 *                              Added configurable debug

 *

 *      11-Jan-2005     BJD     Fixed divide-by-2 in timeout code

 *

 *      25-Jan-2005     DA      Added suspend/resume support

 *                              Replaced reboot notifier with .shutdown method

 *

 *      10-Mar-2005     LCVR    Changed S3C2410_VA to S3C24XX_VA

*/

#include <linux/module.h>

#include <linux/moduleparam.h>

#include <linux/types.h>

#include <linux/timer.h>

#include <linux/miscdevice.h>

#include <linux/watchdog.h>

#include <linux/fs.h>

#include <linux/init.h>

#include <linux/platform_device.h>

#include <linux/interrupt.h>

#include <linux/clk.h>

#include <asm/uaccess.h>

#include <asm/io.h>

#include <asm/arch/map.h>

#undef S3C_VA_WATCHDOG

#define S3C_VA_WATCHDOG (0)

#include <asm/plat-s3c/regs-watchdog.h>

#define PFX "s3c2410-wdt: "

#define CONFIG_S3C2410_WATCHDOG_ATBOOT          (0)

#define CONFIG_S3C2410_WATCHDOG_DEFAULT_TIME    (15)

static int nowayout     = WATCHDOG_NOWAYOUT;

static int tmr_margin   = CONFIG_S3C2410_WATCHDOG_DEFAULT_TIME;

static int tmr_atboot   = CONFIG_S3C2410_WATCHDOG_ATBOOT;

static int soft_noboot  = 0;

static int debug        = 0;

module_param(tmr_margin,  int, 0);

module_param(tmr_atboot,  int, 0);

module_param(nowayout,    int, 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 depends on ONLY_TESTING)");

MODULE_PARM_DESC(debug, "Watchdog debug, set to >1 for debug, (default 0)");

typedef enum close_state {

        CLOSE_STATE_NOT,

        CLOSE_STATE_ALLOW=0x4021

} close_state_t;

static DECLARE_MUTEX(open_lock);

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 close_state_t     allow_close;

/* watchdog control routines */

#define DBG(msg...) do { \

        if (debug) \

                printk(KERN_INFO msg); \

        } while(0)

/* functions */

static int s3c2410wdt_keepalive(void)

{

        writel(wdt_count, wdt_base + S3C2410_WTCNT);

        return 0;

}

static int 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);

        return 0;

}

static int s3c2410wdt_start(void)

{

        unsigned long wtcon;

        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",

            __FUNCTION__, wdt_count, wtcon);

        writel(wdt_count, wdt_base + S3C2410_WTDAT);

        writel(wdt_count, wdt_base + S3C2410_WTCNT);

        writel(wtcon, wdt_base + S3C2410_WTCON);

        return 0;

}

static int s3c2410wdt_set_heartbeat(int timeout)

{

        unsigned int 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=%d\n",

            __FUNCTION__, 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;

                }

        }

        tmr_margin = timeout;

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

            __FUNCTION__, 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);

        return 0;

}

/*

 *      /dev/watchdog handling

 */

static int s3c2410wdt_open(struct inode *inode, struct file *file)

{

        if(down_trylock(&open_lock))

                return -EBUSY;

        if (nowayout)

                __module_get(THIS_MODULE);

        allow_close = CLOSE_STATE_NOT;

        /* start the timer */

        s3c2410wdt_start();

        return nonseekable_open(inode, file);

}

static int s3c2410wdt_release(struct inode *inode, struct file *file)

{

        /*

         *      Shut off the timer.

         *      Lock it in if it's a module and we set nowayout

         */

        if (allow_close == CLOSE_STATE_ALLOW) {

                s3c2410wdt_stop();

        } else {

                dev_err(wdt_dev, "Unexpected close, not stopping watchdog\n");

                s3c2410wdt_keepalive();

        }

        allow_close = CLOSE_STATE_NOT;

        up(&open_lock);

        return 0;

}

static ssize_t s3c2410wdt_write(struct file *file, const char __user *data,

                                size_t len, loff_t *ppos)

{

        /*

         *      Refresh the timer.

         */

        if(len) {

                if (!nowayout) {

                        size_t i;

                        /* In case it was set long ago */

                        allow_close = CLOSE_STATE_NOT;

                        for (i = 0; i != len; i++) {

                                char c;

                                if (get_user(c, data + i))

                                        return -EFAULT;

                                if (c == 'V')

                                        allow_close = CLOSE_STATE_ALLOW;

                        }

                }

                s3c2410wdt_keepalive();

        }

        return len;

}

#define OPTIONS WDIOF_SETTIMEOUT | WDIOF_KEEPALIVEPING | WDIOF_MAGICCLOSE

static struct watchdog_info s3c2410_wdt_ident = {

        .options          =     OPTIONS,

        .firmware_version =     0,

        .identity         =     "S3C2410 Watchdog",

};

static int s3c2410wdt_ioctl(struct inode *inode, struct file *file,

        unsigned int cmd, unsigned long arg)

{

        void __user *argp = (void __user *)arg;

        int __user *p = argp;

        int new_margin;

        switch (cmd) {

                default:

                        return -ENOTTY;

                case WDIOC_GETSUPPORT:

                        return copy_to_user(argp, &s3c2410_wdt_ident,

                                sizeof(s3c2410_wdt_ident)) ? -EFAULT : 0;

                case WDIOC_GETSTATUS:

                case WDIOC_GETBOOTSTATUS:

                        return put_user(0, p);

                case WDIOC_KEEPALIVE:

                        s3c2410wdt_keepalive();

                        return 0;

                case WDIOC_SETTIMEOUT:

                        if (get_user(new_margin, p))

                                return -EFAULT;

                        if (s3c2410wdt_set_heartbeat(new_margin))

                                return -EINVAL;

                        s3c2410wdt_keepalive();

                        return put_user(tmr_margin, p);

                case WDIOC_GETTIMEOUT:

                        return put_user(tmr_margin, p);

        }

}

/* kernel interface */

static const struct file_operations s3c2410wdt_fops = {

        .owner          = THIS_MODULE,

        .llseek         = no_llseek,

        .write          = s3c2410wdt_write,

        .ioctl          = s3c2410wdt_ioctl,

        .open           = s3c2410wdt_open,

        .release        = s3c2410wdt_release,

};

static struct miscdevice s3c2410wdt_miscdev = {

        .minor          = WATCHDOG_MINOR,

        .name           = "watchdog",

        .fops           = &s3c2410wdt_fops,

};

/* interrupt handler code */

static irqreturn_t s3c2410wdt_irq(int irqno, void *param)

{

        dev_info(wdt_dev, "watchdog timer expired (irq)\n");

        s3c2410wdt_keepalive();

        return IRQ_HANDLED;

}

/* device interface */

static int s3c2410wdt_probe(struct platform_device *pdev)

{

        struct resource *res;

        struct device *dev;

        unsigned int wtcon;

        int started = 0;

        int ret;

        int size;

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

        dev = &pdev->dev;

        wdt_dev = &pdev->dev;

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

        res = platform_get_resource(pdev, IORESOURCE_MEM, 0);

        if (res == NULL) {

                dev_err(dev, "no memory resource specified\n");

                return -ENOENT;

        }

        size = (res->end-res->start)+1;

        wdt_mem = request_mem_region(res->start, size, pdev->name);

        if (wdt_mem == NULL) {

                dev_err(dev, "failed to get memory region\n");

                ret = -ENOENT;

                goto err_req;

        }

        wdt_base = ioremap(res->start, size);

        if (wdt_base == 0) {

                dev_err(dev, "failed to ioremap() region\n");

                ret = -EINVAL;

                goto err_req;

        }

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

        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_map;

        }

        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_map;

        }

        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_irq;

        }

        clk_enable(wdt_clock);

        /* see if we can actually set the requested timer margin, and if

         * not, try the default value */

        if (s3c2410wdt_set_heartbeat(tmr_margin)) {

                started = s3c2410wdt_set_heartbeat(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 = misc_register(&s3c2410wdt_miscdev);

        if (ret) {

                dev_err(dev, "cannot register miscdev on minor=%d (%d)\n",

                        WATCHDOG_MINOR, ret);

                goto err_clk;

        }

        if (tmr_atboot && started == 0) {

                dev_info(dev, "starting watchdog timer\n");

                s3c2410wdt_start();

        } 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();

        }

        /* 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) ? "" : "dis",

                 (wtcon & S3C2410_WTCON_INTEN) ? "" : "en");

        return 0;

 err_clk:

        clk_disable(wdt_clock);

        clk_put(wdt_clock);

 err_irq:

        free_irq(wdt_irq->start, pdev);

 err_map:

        iounmap(wdt_base);

 err_req:

        release_resource(wdt_mem);

        kfree(wdt_mem);

        return ret;

}

static int s3c2410wdt_remove(struct platform_device *dev)

{

        release_resource(wdt_mem);

        kfree(wdt_mem);

        wdt_mem = NULL;

        free_irq(wdt_irq->start, dev);

        wdt_irq = NULL;

        clk_disable(wdt_clock);

        clk_put(wdt_clock);

        wdt_clock = NULL;

        iounmap(wdt_base);

        misc_deregister(&s3c2410wdt_miscdev);

        return 0;

}

static void s3c2410wdt_shutdown(struct platform_device *dev)

{

        s3c2410wdt_stop();

}

#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();

        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);

        printk(KERN_INFO PFX "watchdog %sabled\n",

               (wtcon_save & S3C2410_WTCON_ENABLE) ? "en" : "dis");

        return 0;

}

#else

#define s3c2410wdt_suspend NULL

#define s3c2410wdt_resume  NULL

#endif /* CONFIG_PM */

static struct platform_driver s3c2410wdt_driver = {

        .probe          = s3c2410wdt_probe,

        .remove         = s3c2410wdt_remove,

        .shutdown       = s3c2410wdt_shutdown,

        .suspend        = s3c2410wdt_suspend,

        .resume         = s3c2410wdt_resume,

        .driver         = {

                .owner  = THIS_MODULE,

                .name   = "s3c2410-wdt",

        },

};

static char banner[] __initdata = KERN_INFO "S3C2410 Watchdog Timer, (c) 2004 Simtec Electronics\n";

static int __init watchdog_init(void)

{

        printk(banner);

        return platform_driver_register(&s3c2410wdt_driver);

}

static void __exit watchdog_exit(void)

{

        platform_driver_unregister(&s3c2410wdt_driver);

}

module_init(watchdog_init);

module_exit(watchdog_exit);

MODULE_AUTHOR("Ben Dooks <ben@simtec.co.uk>, "

              "Dimitry Andric <dimitry.andric@tomtom.com>");

MODULE_DESCRIPTION("S3C2410 Watchdog Device Driver");

MODULE_LICENSE("GPL");

MODULE_ALIAS_MISCDEV(WATCHDOG_MINOR);