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/*

 *      IB700 Single Board Computer WDT driver

 *

 *      (c) Copyright 2001 Charles Howes <chowes@vsol.net>

 *

 *      Based on advantechwdt.c which is based on acquirewdt.c which

 *      is based on wdt.c.

 *

 *      (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

 *           Added timeout module option to override default

 *

 */

#include <linux/module.h>

#include <linux/types.h>

#include <linux/miscdevice.h>

#include <linux/watchdog.h>

#include <linux/ioport.h>

#include <linux/fs.h>

#include <linux/init.h>

#include <linux/spinlock.h>

#include <linux/moduleparam.h>

#include <linux/platform_device.h>

#include <asm/io.h>

#include <asm/uaccess.h>

#include <asm/system.h>

static struct platform_device *ibwdt_platform_device;

static unsigned long ibwdt_is_open;

static DEFINE_SPINLOCK(ibwdt_lock);

static char expect_close;

/* Module information */

#define DRV_NAME "ib700wdt"

#define PFX DRV_NAME ": "

/*

 *

 * Watchdog Timer Configuration

 *

 * The function of the watchdog timer is to reset the system

 * automatically and is defined at I/O port 0443H.  To enable the

 * watchdog timer and allow the system to reset, write I/O port 0443H.

 * To disable the timer, write I/O port 0441H for the system to stop the

 * watchdog function.  The timer has a tolerance of 20% for its

 * intervals.

 *

 * The following describes how the timer should be programmed.

 *

 * Enabling Watchdog:

 * MOV AX,000FH (Choose the values from 0 to F)

 * MOV DX,0443H

 * OUT DX,AX

 *

 * Disabling Watchdog:

 * MOV AX,000FH (Any value is fine.)

 * MOV DX,0441H

 * OUT DX,AX

 *

 * Watchdog timer control table:

 * Level   Value  Time/sec | Level Value Time/sec

 *   1       F       0     |   9     7      16

 *   2       E       2     |   10    6      18

 *   3       D       4     |   11    5      20

 *   4       C       6     |   12    4      22

 *   5       B       8     |   13    3      24

 *   6       A       10    |   14    2      26

 *   7       9       12    |   15    1      28

 *   8       8       14    |   16    0      30

 *

 */

static int wd_times[] = {

        30,     /* 0x0 */

        28,     /* 0x1 */

        26,     /* 0x2 */

        24,     /* 0x3 */

        22,     /* 0x4 */

        20,     /* 0x5 */

        18,     /* 0x6 */

        16,     /* 0x7 */

        14,     /* 0x8 */

        12,     /* 0x9 */

        10,     /* 0xA */

        8,      /* 0xB */

        6,      /* 0xC */

        4,      /* 0xD */

        2,      /* 0xE */

        0,       /* 0xF */

};

#define WDT_STOP 0x441

#define WDT_START 0x443

/* Default timeout */

#define WD_TIMO 0               /* 30 seconds +/- 20%, from table */

static int wd_margin = WD_TIMO;

static int nowayout = WATCHDOG_NOWAYOUT;

module_param(nowayout, int, 0);

MODULE_PARM_DESC(nowayout, "Watchdog cannot be stopped once started (default=" __MODULE_STRING(WATCHDOG_NOWAYOUT) ")");

/*

 *      Watchdog Operations

 */

static void

ibwdt_ping(void)

{

        spin_lock(&ibwdt_lock);

        /* Write a watchdog value */

        outb_p(wd_margin, WDT_START);

        spin_unlock(&ibwdt_lock);

}

static void

ibwdt_disable(void)

{

        spin_lock(&ibwdt_lock);

        outb_p(0, WDT_STOP);

        spin_unlock(&ibwdt_lock);

}

static int

ibwdt_set_heartbeat(int t)

{

        int i;

        if ((t < 0) || (t > 30))

                return -EINVAL;

        for (i = 0x0F; i > -1; i--)

                if (wd_times[i] > t)

                        break;

        wd_margin = i;

        return 0;

}

/*

 *      /dev/watchdog handling

 */

static ssize_t

ibwdt_write(struct file *file, const char __user *buf, size_t count, loff_t *ppos)

{

        if (count) {

                if (!nowayout) {

                        size_t i;

                        /* In case it was set long ago */

                        expect_close = 0;

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

                                char c;

                                if (get_user(c, buf + i))

                                        return -EFAULT;

                                if (c == 'V')

                                        expect_close = 42;

                        }

                }

                ibwdt_ping();

        }

        return count;

}

static int

ibwdt_ioctl(struct inode *inode, struct file *file, unsigned int cmd,

          unsigned long arg)

{

        int new_margin;

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

        int __user *p = argp;

        static struct watchdog_info ident = {

                .options = WDIOF_KEEPALIVEPING | WDIOF_SETTIMEOUT | WDIOF_MAGICCLOSE,

                .firmware_version = 1,

                .identity = "IB700 WDT",

        };

        switch (cmd) {

        case WDIOC_GETSUPPORT:

          if (copy_to_user(argp, &ident, sizeof(ident)))

            return -EFAULT;

          break;

        case WDIOC_GETSTATUS:

        case WDIOC_GETBOOTSTATUS:

          return put_user(0, p);

        case WDIOC_KEEPALIVE:

          ibwdt_ping();

          break;

        case WDIOC_SETTIMEOUT:

          if (get_user(new_margin, p))

                  return -EFAULT;

          if (ibwdt_set_heartbeat(new_margin))

                  return -EINVAL;

          ibwdt_ping();

          /* Fall */

        case WDIOC_GETTIMEOUT:

          return put_user(wd_times[wd_margin], p);

        case WDIOC_SETOPTIONS:

        {

          int options, retval = -EINVAL;

          if (get_user(options, p))

            return -EFAULT;

          if (options & WDIOS_DISABLECARD) {

            ibwdt_disable();

            retval = 0;

          }

          if (options & WDIOS_ENABLECARD) {

            ibwdt_ping();

            retval = 0;

          }

          return retval;

        }

        default:

          return -ENOTTY;

        }

        return 0;

}

static int

ibwdt_open(struct inode *inode, struct file *file)

{

        if (test_and_set_bit(0, &ibwdt_is_open)) {

                return -EBUSY;

        }

        if (nowayout)

                __module_get(THIS_MODULE);

        /* Activate */

        ibwdt_ping();

        return nonseekable_open(inode, file);

}

static int

ibwdt_close(struct inode *inode, struct file *file)

{

        if (expect_close == 42) {

                ibwdt_disable();

        } else {

                printk(KERN_CRIT PFX "WDT device closed unexpectedly.  WDT will not stop!\n");

                ibwdt_ping();

        }

        clear_bit(0, &ibwdt_is_open);

        expect_close = 0;

        return 0;

}

/*

 *      Kernel Interfaces

 */

static const struct file_operations ibwdt_fops = {

        .owner          = THIS_MODULE,

        .llseek         = no_llseek,

        .write          = ibwdt_write,

        .ioctl          = ibwdt_ioctl,

        .open           = ibwdt_open,

        .release        = ibwdt_close,

};

static struct miscdevice ibwdt_miscdev = {

        .minor = WATCHDOG_MINOR,

        .name = "watchdog",

        .fops = &ibwdt_fops,

};

/*

 *      Init & exit routines

 */

static int __devinit ibwdt_probe(struct platform_device *dev)

{

        int res;

#if WDT_START != WDT_STOP

        if (!request_region(WDT_STOP, 1, "IB700 WDT")) {

                printk (KERN_ERR PFX "STOP method I/O %X is not available.\n", WDT_STOP);

                res = -EIO;

                goto out_nostopreg;

        }

#endif

        if (!request_region(WDT_START, 1, "IB700 WDT")) {

                printk (KERN_ERR PFX "START method I/O %X is not available.\n", WDT_START);

                res = -EIO;

                goto out_nostartreg;

        }

        res = misc_register(&ibwdt_miscdev);

        if (res) {

                printk (KERN_ERR PFX "failed to register misc device\n");

                goto out_nomisc;

        }

        return 0;

out_nomisc:

        release_region(WDT_START, 1);

out_nostartreg:

#if WDT_START != WDT_STOP

        release_region(WDT_STOP, 1);

#endif

out_nostopreg:

        return res;

}

static int __devexit ibwdt_remove(struct platform_device *dev)

{

        misc_deregister(&ibwdt_miscdev);

        release_region(WDT_START,1);

#if WDT_START != WDT_STOP

        release_region(WDT_STOP,1);

#endif

        return 0;

}

static void ibwdt_shutdown(struct platform_device *dev)

{

        /* Turn the WDT off if we have a soft shutdown */

        ibwdt_disable();

}

static struct platform_driver ibwdt_driver = {

        .probe          = ibwdt_probe,

        .remove         = __devexit_p(ibwdt_remove),

        .shutdown       = ibwdt_shutdown,

        .driver         = {

                .owner  = THIS_MODULE,

                .name   = DRV_NAME,

        },

};

static int __init ibwdt_init(void)

{

        int err;

        printk(KERN_INFO PFX "WDT driver for IB700 single board computer initialising.\n");

        err = platform_driver_register(&ibwdt_driver);

        if (err)

                return err;

        ibwdt_platform_device = platform_device_register_simple(DRV_NAME, -1, NULL, 0);

        if (IS_ERR(ibwdt_platform_device)) {

                err = PTR_ERR(ibwdt_platform_device);

                goto unreg_platform_driver;

        }

        return 0;

unreg_platform_driver:

        platform_driver_unregister(&ibwdt_driver);

        return err;

}

static void __exit ibwdt_exit(void)

{

        platform_device_unregister(ibwdt_platform_device);

        platform_driver_unregister(&ibwdt_driver);

        printk(KERN_INFO PFX "Watchdog Module Unloaded.\n");

}

module_init(ibwdt_init);

module_exit(ibwdt_exit);

MODULE_AUTHOR("Charles Howes <chowes@vsol.net>");

MODULE_DESCRIPTION("IB700 SBC watchdog driver");

MODULE_LICENSE("GPL");

MODULE_ALIAS_MISCDEV(WATCHDOG_MINOR);

/* end of ib700wdt.c */