/*
 *      Advantech Single Board Computer WDT driver for Linux 2.4.x
 *
 *      (c) Copyright 2000-2001 Marek Michalkiewicz <marekm@linux.org.pl>
 *
 *      Based on acquirewdt.c which is based on wdt.c.
 *      Original copyright messages:
 *
 *      (c) Copyright 1996 Alan Cox <alan@redhat.com>, All Rights Reserved.
 *                              http://www.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.
 *
 *      Neither Alan Cox nor CymruNet Ltd. admit liability nor provide
 *      warranty for any of this software. This material is provided
 *      "AS-IS" and at no charge.
 *
 *      (c) Copyright 1995    Alan Cox <alan@redhat.com>
 *
 *      14-Dec-2001 Matt Domsch <Matt_Domsch@dell.com>
 *          Added nowayout module option to override CONFIG_WATCHDOG_NOWAYOUT
 */

#include <linux/config.h>
#include <linux/module.h>
#include <linux/types.h>
#include <linux/errno.h>
#include <linux/kernel.h>
#include <linux/miscdevice.h>
#include <linux/watchdog.h>
#include <linux/ioport.h>
#include <linux/fcntl.h>
#include <asm/io.h>
#include <asm/uaccess.h>
#include <asm/system.h>
#include <linux/notifier.h>
#include <linux/reboot.h>
#include <linux/init.h>

static unsigned long advwdt_is_open;
static char adv_expect_close;

/*
 *      You must set these - there is no sane way to probe for this board.
 *
 *      To enable or restart, write the timeout value in seconds (1 to 63)
 *      to I/O port wdt_start.  To disable, read I/O port wdt_stop.
 *      Both are 0x443 for most boards (tested on a PCA-6276VE-00B1), but
 *      check your manual (at least the PCA-6159 seems to be different -
 *      the manual says wdt_stop is 0x43, not 0x443).
 *      (0x43 is also a write-only control register for the 8254 timer!)
 */
 
static int wdt_stop = 0x443;
static int wdt_start = 0x443;

static int wd_margin = 60; /* 60 sec default timeout */

#ifdef CONFIG_WATCHDOG_NOWAYOUT
static int nowayout = 1;
#else
static int nowayout = 0;
#endif

MODULE_PARM(nowayout,"i");
MODULE_PARM_DESC(nowayout, "Watchdog cannot be stopped once started (default=CONFIG_WATCHDOG_NOWAYOUT)");

/*
 *      Kernel methods.
 */

#ifndef MODULE

static int __init adv_setup(char *str)
{
        int ints[4];

        str = get_options(str, ARRAY_SIZE(ints), ints);

        if(ints[0] > 0){
                wdt_stop = ints[1];
                if(ints[0] > 1)
                        wdt_start = ints[2];
        }

        return 1;
}

__setup("advwdt=", adv_setup);

#endif /* !MODULE */

MODULE_PARM(wdt_stop, "i");
MODULE_PARM_DESC(wdt_stop, "Advantech WDT 'stop' io port (default 0x443)");
MODULE_PARM(wdt_start, "i");
MODULE_PARM_DESC(wdt_start, "Advantech WDT 'start' io port (default 0x443)");

static void
advwdt_ping(void)
{
        /* Write a watchdog value */
        outb_p(wd_margin, wdt_start);
}

static void
advwdt_disable(void)
{
        inb_p(wdt_stop);
}

static ssize_t
advwdt_write(struct file *file, const char *buf, size_t count, loff_t *ppos)
{
        /*  Can't seek (pwrite) on this device  */
        if (ppos != &file->f_pos)
                return -ESPIPE;

        if (count) {
                if (!nowayout) {
                        size_t i;

                        adv_expect_close = 0;
        
                        for (i = 0; i != count; i++) {
                                char c;
                                if(get_user(c, buf+i))
                                        return -EFAULT;
                                if (c == 'V')
                                        adv_expect_close = 42;
                        }
                }
                        advwdt_ping();
        }
        return count;
}

static int
advwdt_ioctl(struct inode *inode, struct file *file, unsigned int cmd,
          unsigned long arg)
{
        int new_margin;
        static struct watchdog_info ident = {
                options:                WDIOF_KEEPALIVEPING | WDIOF_SETTIMEOUT | WDIOF_MAGICCLOSE,
                firmware_version:       0,
                identity:               "Advantech WDT"
        };

        switch (cmd) {
        case WDIOC_GETSUPPORT:
          if (copy_to_user((struct watchdog_info *)arg, &ident, sizeof(ident)))
            return -EFAULT;
          break;

        case WDIOC_GETSTATUS:
        case WDIOC_GETBOOTSTATUS:
          return put_user(0, (int *)arg);

        case WDIOC_KEEPALIVE:
          advwdt_ping();
          break;

        case WDIOC_SETTIMEOUT:
          if (get_user(new_margin, (int *)arg))
                  return -EFAULT;
          if ((new_margin < 1) || (new_margin > 63))
                  return -EINVAL;
          wd_margin = new_margin;
          advwdt_ping();
          /* Fall */

        case WDIOC_GETTIMEOUT:
          return put_user(wd_margin, (int *)arg);

        case WDIOC_SETOPTIONS:
        {
          int options, retval = -EINVAL;

          if (get_user(options, (int *)arg))
            return -EFAULT;

          if (options & WDIOS_DISABLECARD) {
            advwdt_disable();
            retval = 0;
          }

          if (options & WDIOS_ENABLECARD) {
            advwdt_ping();
            retval = 0;
          }

          return retval;
        }

        default:
          return -ENOTTY;
        }
        return 0;
}

static int
advwdt_open(struct inode *inode, struct file *file)
{
        if (test_and_set_bit(0, &advwdt_is_open))
                return -EBUSY;
        /*
         *      Activate
         */

        advwdt_ping();
        return 0;
}

static int
advwdt_close(struct inode *inode, struct file *file)
{
        if (adv_expect_close == 42) {
                advwdt_disable();
        } else {
                printk(KERN_CRIT "advancetechwdt: Unexpected close, not stopping watchdog!\n");
                advwdt_ping();
        }
        clear_bit(0, &advwdt_is_open);
        adv_expect_close = 0;
        return 0;
}

/*
 *      Notifier for system down
 */

static int
advwdt_notify_sys(struct notifier_block *this, unsigned long code,
        void *unused)
{
        if (code == SYS_DOWN || code == SYS_HALT) {
                /* Turn the WDT off */
                advwdt_disable();
        }
        return NOTIFY_DONE;
}
 
/*
 *      Kernel Interfaces
 */
 
static struct file_operations advwdt_fops = {
        owner:          THIS_MODULE,
        llseek:         no_llseek,
        write:          advwdt_write,
        ioctl:          advwdt_ioctl,
        open:           advwdt_open,
        release:        advwdt_close,
};

static struct miscdevice advwdt_miscdev = {
        minor:          WATCHDOG_MINOR,
        name:           "watchdog",
        fops:           &advwdt_fops,
};

/*
 *      The WDT needs to learn about soft shutdowns in order to
 *      turn the timebomb registers off.
 */
 
static struct notifier_block advwdt_notifier = {
        advwdt_notify_sys,
        NULL,
        0
};

static int __init
advwdt_init(void)
{
        printk(KERN_INFO "WDT driver for Advantech single board computer initialising.\n");

        misc_register(&advwdt_miscdev);
        if(wdt_stop != wdt_start)
                request_region(wdt_stop, 1, "Advantech WDT");
        request_region(wdt_start, 1, "Advantech WDT");
        register_reboot_notifier(&advwdt_notifier);
        return 0;
}

static void __exit
advwdt_exit(void)
{
        misc_deregister(&advwdt_miscdev);
        unregister_reboot_notifier(&advwdt_notifier);
        if(wdt_stop != wdt_start)
                release_region(wdt_stop,1);
        release_region(wdt_start,1);
}

module_init(advwdt_init);
module_exit(advwdt_exit);

MODULE_LICENSE("GPL");
MODULE_AUTHOR("Marek Michalkiewicz <marekm@linux.org.pl>");
MODULE_DESCRIPTION("Advantech Single Board Computer WDT driver");
EXPORT_NO_SYMBOLS;

/* end of advantechwdt.c */