/*
 *      Industrial Computer Source WDT500/501 driver
 *
 *      (c) Copyright 1996-1997 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@lxorguk.ukuu.org.uk>
 *
 *      Release 0.10.
 *
 *      Fixes
 *              Dave Gregorich  :       Modularisation and minor bugs
 *              Alan Cox        :       Added the watchdog ioctl() stuff
 *              Alan Cox        :       Fixed the reboot problem (as noted by
 *                                      Matt Crocker).
 *              Alan Cox        :       Added wdt= boot option
 *              Alan Cox        :       Cleaned up copy/user stuff
 *              Tim Hockin      :       Added insmod parameters, comment cleanup
 *                                      Parameterized timeout
 *              Tigran Aivazian :       Restructured wdt_init() to handle failures
 *              Joel Becker     :       Added WDIOC_GET/SETTIMEOUT
 *              Matt Domsch     :       Added nowayout module option
 */

#include <linux/interrupt.h>
#include <linux/module.h>
#include <linux/moduleparam.h>
#include <linux/types.h>
#include <linux/miscdevice.h>
#include <linux/watchdog.h>
#include <linux/fs.h>
#include <linux/ioport.h>
#include <linux/notifier.h>
#include <linux/reboot.h>
#include <linux/init.h>

#include <asm/io.h>
#include <asm/uaccess.h>
#include <asm/system.h>
#include "wd501p.h"

static unsigned long wdt_is_open;
static char expect_close;

/*
 *      Module parameters
 */

#define WD_TIMO 60                      /* Default heartbeat = 60 seconds */

static int heartbeat = WD_TIMO;
static int wd_heartbeat;
module_param(heartbeat, int, 0);
MODULE_PARM_DESC(heartbeat, "Watchdog heartbeat in seconds. (0<heartbeat<65536, default=" __MODULE_STRING(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) ")");

/* You must set these - there is no sane way to probe for this board. */
static int io=0x240;
static int irq=11;

module_param(io, int, 0);
MODULE_PARM_DESC(io, "WDT io port (default=0x240)");
module_param(irq, int, 0);
MODULE_PARM_DESC(irq, "WDT irq (default=11)");

#ifdef CONFIG_WDT_501
/* Support for the Fan Tachometer on the WDT501-P */
static int tachometer;

module_param(tachometer, int, 0);
MODULE_PARM_DESC(tachometer, "WDT501-P Fan Tachometer support (0=disable, default=0)");
#endif /* CONFIG_WDT_501 */

/*
 *      Programming support
 */

static void wdt_ctr_mode(int ctr, int mode)
{
        ctr<<=6;
        ctr|=0x30;
        ctr|=(mode<<1);
        outb_p(ctr, WDT_CR);
}

static void wdt_ctr_load(int ctr, int val)
{
        outb_p(val&0xFF, WDT_COUNT0+ctr);
        outb_p(val>>8, WDT_COUNT0+ctr);
}

/**
 *      wdt_start:
 *
 *      Start the watchdog driver.
 */

static int wdt_start(void)
{
        inb_p(WDT_DC);                  /* Disable watchdog */
        wdt_ctr_mode(0,3);              /* Program CTR0 for Mode 3: Square Wave Generator */
        wdt_ctr_mode(1,2);              /* Program CTR1 for Mode 2: Rate Generator */
        wdt_ctr_mode(2,0);              /* Program CTR2 for Mode 0: Pulse on Terminal Count */
        wdt_ctr_load(0, 8948);          /* Count at 100Hz */
        wdt_ctr_load(1,wd_heartbeat);   /* Heartbeat */
        wdt_ctr_load(2,65535);          /* Length of reset pulse */
        outb_p(0, WDT_DC);              /* Enable watchdog */
        return 0;
}

/**
 *      wdt_stop:
 *
 *      Stop the watchdog driver.
 */

static int wdt_stop (void)
{
        /* Turn the card off */
        inb_p(WDT_DC);                  /* Disable watchdog */
        wdt_ctr_load(2,0);              /* 0 length reset pulses now */
        return 0;
}

/**
 *      wdt_ping:
 *
 *      Reload counter one with the watchdog heartbeat. We don't bother reloading
 *      the cascade counter.
 */

static int wdt_ping(void)
{
        /* Write a watchdog value */
        inb_p(WDT_DC);                  /* Disable watchdog */
        wdt_ctr_mode(1,2);              /* Re-Program CTR1 for Mode 2: Rate Generator */
        wdt_ctr_load(1,wd_heartbeat);   /* Heartbeat */
        outb_p(0, WDT_DC);              /* Enable watchdog */
        return 0;
}

/**
 *      wdt_set_heartbeat:
 *      @t:             the new heartbeat value that needs to be set.
 *
 *      Set a new heartbeat value for the watchdog device. If the heartbeat value is
 *      incorrect we keep the old value and return -EINVAL. If successfull we
 *      return 0.
 */
static int wdt_set_heartbeat(int t)
{
        if ((t < 1) || (t > 65535))
                return -EINVAL;

        heartbeat = t;
        wd_heartbeat = t * 100;
        return 0;
}

/**
 *      wdt_get_status:
 *      @status:                the new status.
 *
 *      Extract the status information from a WDT watchdog device. There are
 *      several board variants so we have to know which bits are valid. Some
 *      bits default to one and some to zero in order to be maximally painful.
 *
 *      we then map the bits onto the status ioctl flags.
 */

static int wdt_get_status(int *status)
{
        unsigned char new_status=inb_p(WDT_SR);

        *status=0;
        if (new_status & WDC_SR_ISOI0)
                *status |= WDIOF_EXTERN1;
        if (new_status & WDC_SR_ISII1)
                *status |= WDIOF_EXTERN2;
#ifdef CONFIG_WDT_501
        if (!(new_status & WDC_SR_TGOOD))
                *status |= WDIOF_OVERHEAT;
        if (!(new_status & WDC_SR_PSUOVER))
                *status |= WDIOF_POWEROVER;
        if (!(new_status & WDC_SR_PSUUNDR))
                *status |= WDIOF_POWERUNDER;
        if (tachometer) {
                if (!(new_status & WDC_SR_FANGOOD))
                        *status |= WDIOF_FANFAULT;
        }
#endif /* CONFIG_WDT_501 */
        return 0;
}

#ifdef CONFIG_WDT_501
/**
 *      wdt_get_temperature:
 *
 *      Reports the temperature in degrees Fahrenheit. The API is in
 *      farenheit. It was designed by an imperial measurement luddite.
 */

static int wdt_get_temperature(int *temperature)
{
        unsigned short c=inb_p(WDT_RT);

        *temperature = (c * 11 / 15) + 7;
        return 0;
}
#endif /* CONFIG_WDT_501 */

/**
 *      wdt_interrupt:
 *      @irq:           Interrupt number
 *      @dev_id:        Unused as we don't allow multiple devices.
 *
 *      Handle an interrupt from the board. These are raised when the status
 *      map changes in what the board considers an interesting way. That means
 *      a failure condition occurring.
 */

static irqreturn_t wdt_interrupt(int irq, void *dev_id)
{
        /*
         *      Read the status register see what is up and
         *      then printk it.
         */
        unsigned char status=inb_p(WDT_SR);

        printk(KERN_CRIT "WDT status %d\n", status);

#ifdef CONFIG_WDT_501
        if (!(status & WDC_SR_TGOOD))
                printk(KERN_CRIT "Overheat alarm.(%d)\n",inb_p(WDT_RT));
        if (!(status & WDC_SR_PSUOVER))
                printk(KERN_CRIT "PSU over voltage.\n");
        if (!(status & WDC_SR_PSUUNDR))
                printk(KERN_CRIT "PSU under voltage.\n");
        if (tachometer) {
                if (!(status & WDC_SR_FANGOOD))
                        printk(KERN_CRIT "Possible fan fault.\n");
        }
#endif /* CONFIG_WDT_501 */
        if (!(status & WDC_SR_WCCR)) {
#ifdef SOFTWARE_REBOOT
#ifdef ONLY_TESTING
                printk(KERN_CRIT "Would Reboot.\n");
#else
                printk(KERN_CRIT "Initiating system reboot.\n");
                emergency_restart();
#endif
#else
                printk(KERN_CRIT "Reset in 5ms.\n");
#endif
        }
        return IRQ_HANDLED;
}


/**
 *      wdt_write:
 *      @file: file handle to the watchdog
 *      @buf: buffer to write (unused as data does not matter here
 *      @count: count of bytes
 *      @ppos: pointer to the position to write. No seeks allowed
 *
 *      A write to a watchdog device is defined as a keepalive signal. Any
 *      write of data will do, as we we don't define content meaning.
 */

static ssize_t wdt_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;
                        }
                }
                wdt_ping();
        }
        return count;
}

/**
 *      wdt_ioctl:
 *      @inode: inode of the device
 *      @file: file handle to the device
 *      @cmd: watchdog command
 *      @arg: argument pointer
 *
 *      The watchdog API defines a common set of functions for all watchdogs
 *      according to their available features. We only actually usefully support
 *      querying capabilities and current status.
 */

static int wdt_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_heartbeat;
        int status;

        static struct watchdog_info ident = {
                .options =              WDIOF_SETTIMEOUT|
                                        WDIOF_MAGICCLOSE|
                                        WDIOF_KEEPALIVEPING,
                .firmware_version =     1,
                .identity =             "WDT500/501",
        };

        /* Add options according to the card we have */
        ident.options |= (WDIOF_EXTERN1|WDIOF_EXTERN2);
#ifdef CONFIG_WDT_501
        ident.options |= (WDIOF_OVERHEAT|WDIOF_POWERUNDER|WDIOF_POWEROVER);
        if (tachometer)
                ident.options |= WDIOF_FANFAULT;
#endif /* CONFIG_WDT_501 */

        switch(cmd)
        {
                default:
                        return -ENOTTY;
                case WDIOC_GETSUPPORT:
                        return copy_to_user(argp, &ident, sizeof(ident))?-EFAULT:0;

                case WDIOC_GETSTATUS:
                        wdt_get_status(&status);
                        return put_user(status, p);
                case WDIOC_GETBOOTSTATUS:
                        return put_user(0, p);
                case WDIOC_KEEPALIVE:
                        wdt_ping();
                        return 0;
                case WDIOC_SETTIMEOUT:
                        if (get_user(new_heartbeat, p))
                                return -EFAULT;

                        if (wdt_set_heartbeat(new_heartbeat))
                                return -EINVAL;

                        wdt_ping();
                        /* Fall */
                case WDIOC_GETTIMEOUT:
                        return put_user(heartbeat, p);
        }
}

/**
 *      wdt_open:
 *      @inode: inode of device
 *      @file: file handle to device
 *
 *      The watchdog device has been opened. The watchdog device is single
 *      open and on opening we load the counters. Counter zero is a 100Hz
 *      cascade, into counter 1 which downcounts to reboot. When the counter
 *      triggers counter 2 downcounts the length of the reset pulse which
 *      set set to be as long as possible.
 */

static int wdt_open(struct inode *inode, struct file *file)
{
        if(test_and_set_bit(0, &wdt_is_open))
                return -EBUSY;
        /*
         *      Activate
         */
        wdt_start();
        return nonseekable_open(inode, file);
}

/**
 *      wdt_release:
 *      @inode: inode to board
 *      @file: file handle to board
 *
 *      The watchdog has a configurable API. There is a religious dispute
 *      between people who want their watchdog to be able to shut down and
 *      those who want to be sure if the watchdog manager dies the machine
 *      reboots. In the former case we disable the counters, in the latter
 *      case you have to open it again very soon.
 */

static int wdt_release(struct inode *inode, struct file *file)
{
        if (expect_close == 42) {
                wdt_stop();
                clear_bit(0, &wdt_is_open);
        } else {
                printk(KERN_CRIT "wdt: WDT device closed unexpectedly.  WDT will not stop!\n");
                wdt_ping();
        }
        expect_close = 0;
        return 0;
}

#ifdef CONFIG_WDT_501
/**
 *      wdt_temp_read:
 *      @file: file handle to the watchdog board
 *      @buf: buffer to write 1 byte into
 *      @count: length of buffer
 *      @ptr: offset (no seek allowed)
 *
 *      Temp_read reports the temperature in degrees Fahrenheit. The API is in
 *      farenheit. It was designed by an imperial measurement luddite.
 */

static ssize_t wdt_temp_read(struct file *file, char __user *buf, size_t count, loff_t *ptr)
{
        int temperature;

        if (wdt_get_temperature(&temperature))
                return -EFAULT;

        if (copy_to_user (buf, &temperature, 1))
                return -EFAULT;

        return 1;
}

/**
 *      wdt_temp_open:
 *      @inode: inode of device
 *      @file: file handle to device
 *
 *      The temperature device has been opened.
 */

static int wdt_temp_open(struct inode *inode, struct file *file)
{
        return nonseekable_open(inode, file);
}

/**
 *      wdt_temp_release:
 *      @inode: inode to board
 *      @file: file handle to board
 *
 *      The temperature device has been closed.
 */

static int wdt_temp_release(struct inode *inode, struct file *file)
{
        return 0;
}
#endif /* CONFIG_WDT_501 */

/**
 *      notify_sys:
 *      @this: our notifier block
 *      @code: the event being reported
 *      @unused: unused
 *
 *      Our notifier is called on system shutdowns. We want to turn the card
 *      off at reboot otherwise the machine will reboot again during memory
 *      test or worse yet during the following fsck. This would suck, in fact
 *      trust me - if it happens it does suck.
 */

static int wdt_notify_sys(struct notifier_block *this, unsigned long code,
        void *unused)
{
        if(code==SYS_DOWN || code==SYS_HALT) {
                /* Turn the card off */
                wdt_stop();
        }
        return NOTIFY_DONE;
}

/*
 *      Kernel Interfaces
 */


static const struct file_operations wdt_fops = {
        .owner          = THIS_MODULE,
        .llseek         = no_llseek,
        .write          = wdt_write,
        .ioctl          = wdt_ioctl,
        .open           = wdt_open,
        .release        = wdt_release,
};

static struct miscdevice wdt_miscdev = {
        .minor  = WATCHDOG_MINOR,
        .name   = "watchdog",
        .fops   = &wdt_fops,
};

#ifdef CONFIG_WDT_501
static const struct file_operations wdt_temp_fops = {
        .owner          = THIS_MODULE,
        .llseek         = no_llseek,
        .read           = wdt_temp_read,
        .open           = wdt_temp_open,
        .release        = wdt_temp_release,
};

static struct miscdevice temp_miscdev = {
        .minor  = TEMP_MINOR,
        .name   = "temperature",
        .fops   = &wdt_temp_fops,
};
#endif /* CONFIG_WDT_501 */

/*
 *      The WDT card needs to learn about soft shutdowns in order to
 *      turn the timebomb registers off.
 */

static struct notifier_block wdt_notifier = {
        .notifier_call = wdt_notify_sys,
};

/**
 *      cleanup_module:
 *
 *      Unload the watchdog. You cannot do this with any file handles open.
 *      If your watchdog is set to continue ticking on close and you unload
 *      it, well it keeps ticking. We won't get the interrupt but the board
 *      will not touch PC memory so all is fine. You just have to load a new
 *      module in 60 seconds or reboot.
 */

static void __exit wdt_exit(void)
{
        misc_deregister(&wdt_miscdev);
#ifdef CONFIG_WDT_501
        misc_deregister(&temp_miscdev);
#endif /* CONFIG_WDT_501 */
        unregister_reboot_notifier(&wdt_notifier);
        free_irq(irq, NULL);
        release_region(io,8);
}

/**
 *      wdt_init:
 *
 *      Set up the WDT watchdog board. All we have to do is grab the
 *      resources we require and bitch if anyone beat us to them.
 *      The open() function will actually kick the board off.
 */

static int __init wdt_init(void)
{
        int ret;

        /* Check that the heartbeat value is within it's range ; if not reset to the default */
        if (wdt_set_heartbeat(heartbeat)) {
                wdt_set_heartbeat(WD_TIMO);
                printk(KERN_INFO "wdt: heartbeat value must be 0<heartbeat<65536, using %d\n",
                        WD_TIMO);
        }

        if (!request_region(io, 8, "wdt501p")) {
                printk(KERN_ERR "wdt: I/O address 0x%04x already in use\n", io);
                ret = -EBUSY;
                goto out;
        }

        ret = request_irq(irq, wdt_interrupt, IRQF_DISABLED, "wdt501p", NULL);
        if(ret) {
                printk(KERN_ERR "wdt: IRQ %d is not free.\n", irq);
                goto outreg;
        }

        ret = register_reboot_notifier(&wdt_notifier);
        if(ret) {
                printk(KERN_ERR "wdt: cannot register reboot notifier (err=%d)\n", ret);
                goto outirq;
        }

#ifdef CONFIG_WDT_501
        ret = misc_register(&temp_miscdev);
        if (ret) {
                printk(KERN_ERR "wdt: cannot register miscdev on minor=%d (err=%d)\n",
                        TEMP_MINOR, ret);
                goto outrbt;
        }
#endif /* CONFIG_WDT_501 */

        ret = misc_register(&wdt_miscdev);
        if (ret) {
                printk(KERN_ERR "wdt: cannot register miscdev on minor=%d (err=%d)\n",
                        WATCHDOG_MINOR, ret);
                goto outmisc;
        }

        ret = 0;
        printk(KERN_INFO "WDT500/501-P driver 0.10 at 0x%04x (Interrupt %d). heartbeat=%d sec (nowayout=%d)\n",
                io, irq, heartbeat, nowayout);
#ifdef CONFIG_WDT_501
        printk(KERN_INFO "wdt: Fan Tachometer is %s\n", (tachometer ? "Enabled" : "Disabled"));
#endif /* CONFIG_WDT_501 */

out:
        return ret;

outmisc:
#ifdef CONFIG_WDT_501
        misc_deregister(&temp_miscdev);
outrbt:
#endif /* CONFIG_WDT_501 */
        unregister_reboot_notifier(&wdt_notifier);
outirq:
        free_irq(irq, NULL);
outreg:
        release_region(io,8);
        goto out;
}

module_init(wdt_init);
module_exit(wdt_exit);

MODULE_AUTHOR("Alan Cox");
MODULE_DESCRIPTION("Driver for ISA ICS watchdog cards (WDT500/501)");
MODULE_ALIAS_MISCDEV(WATCHDOG_MINOR);
MODULE_ALIAS_MISCDEV(TEMP_MINOR);
MODULE_LICENSE("GPL");