/*
 * PC Watchdog Driver
 * by Ken Hollis (khollis@bitgate.com)
 *
 * Permission granted from Simon Machell (smachell@berkprod.com)
 * Written for the Linux Kernel, and GPLed by Ken Hollis
 *
 * 960107       Added request_region routines, modulized the whole thing.
 * 960108       Fixed end-of-file pointer (Thanks to Dan Hollis), added
 *              WD_TIMEOUT define.
 * 960216       Added eof marker on the file, and changed verbose messages.
 * 960716       Made functional and cosmetic changes to the source for
 *              inclusion in Linux 2.0.x kernels, thanks to Alan Cox.
 * 960717       Removed read/seek routines, replaced with ioctl.  Also, added
 *              check_region command due to Alan's suggestion.
 * 960821       Made changes to compile in newer 2.0.x kernels.  Added
 *              "cold reboot sense" entry.
 * 960825       Made a few changes to code, deleted some defines and made
 *              typedefs to replace them.  Made heartbeat reset only available
 *              via ioctl, and removed the write routine.
 * 960828       Added new items for PC Watchdog Rev.C card.
 * 960829       Changed around all of the IOCTLs, added new features,
 *              added watchdog disable/re-enable routines.  Added firmware
 *              version reporting.  Added read routine for temperature.
 *              Removed some extra defines, added an autodetect Revision
 *              routine.
 * 961006       Revised some documentation, fixed some cosmetic bugs.  Made
 *              drivers to panic the system if it's overheating at bootup.
 * 961118       Changed some verbiage on some of the output, tidied up
 *              code bits, and added compatibility to 2.1.x.
 * 970912       Enabled board on open and disable on close.
 * 971107       Took account of recent VFS changes (broke read).
 * 971210       Disable board on initialisation in case board already ticking.
 * 971222       Changed open/close for temperature handling
 *              Michael Meskes <meskes@debian.org>.
 * 980112       Used minor numbers from include/linux/miscdevice.h
 * 990403       Clear reset status after reading control status register in
 *              pcwd_showprevstate(). [Marc Boucher <marc@mbsi.ca>]
 * 990605       Made changes to code to support Firmware 1.22a, added
 *              fairly useless proc entry.
 * 990610       removed said useless proc code for the merge <alan>
 * 000403       Removed last traces of proc code. <davej>
 * 011214       Added nowayout module option to override
 *              CONFIG_WATCHDOG_NOWAYOUT <Matt_Domsch@dell.com>
 *              Added timeout module option to override default
 */

/*
 *      A bells and whistles driver is available from http://www.pcwd.de/
 *      More info available at http://www.berkprod.com/ or
 *      http://www.pcwatchdog.com/
 */

#include <linux/module.h>       /* For module specific items */
#include <linux/moduleparam.h>  /* For new moduleparam's */
#include <linux/types.h>        /* For standard types (like size_t) */
#include <linux/errno.h>        /* For the -ENODEV/... values */
#include <linux/kernel.h>       /* For printk/panic/... */
#include <linux/delay.h>        /* For mdelay function */
#include <linux/timer.h>        /* For timer related operations */
#include <linux/jiffies.h>      /* For jiffies stuff */
#include <linux/miscdevice.h>   /* For MODULE_ALIAS_MISCDEV(WATCHDOG_MINOR) */
#include <linux/watchdog.h>     /* For the watchdog specific items */
#include <linux/reboot.h>       /* For kernel_power_off() */
#include <linux/init.h>         /* For __init/__exit/... */
#include <linux/fs.h>           /* For file operations */
#include <linux/isa.h>          /* For isa devices */
#include <linux/ioport.h>       /* For io-port access */
#include <linux/spinlock.h>     /* For spin_lock/spin_unlock/... */
#include <linux/uaccess.h>      /* For copy_to_user/put_user/... */
#include <linux/io.h>           /* For inb/outb/... */

/* Module and version information */
#define WATCHDOG_VERSION "1.20"
#define WATCHDOG_DATE "18 Feb 2007"
#define WATCHDOG_DRIVER_NAME "ISA-PC Watchdog"
#define WATCHDOG_NAME "pcwd"
#define PFX WATCHDOG_NAME ": "
#define DRIVER_VERSION WATCHDOG_DRIVER_NAME " driver, v" WATCHDOG_VERSION "\n"

/*
 * It should be noted that PCWD_REVISION_B was removed because A and B
 * are essentially the same types of card, with the exception that B
 * has temperature reporting.  Since I didn't receive a Rev.B card,
 * the Rev.B card is not supported.  (It's a good thing too, as they
 * are no longer in production.)
 */
#define PCWD_REVISION_A         1
#define PCWD_REVISION_C         2

/*
 * These are the auto-probe addresses available.
 *
 * Revision A only uses ports 0x270 and 0x370.  Revision C introduced 0x350.
 * Revision A has an address range of 2 addresses, while Revision C has 4.
 */
#define PCWD_ISA_NR_CARDS       3
static int pcwd_ioports[] = { 0x270, 0x350, 0x370, 0x000 };

/*
 * These are the defines that describe the control status bits for the
 * PCI-PC Watchdog card.
*/
/* Port 1 : Control Status #1 for the PC Watchdog card, revision A. */
#define WD_WDRST                0x01    /* Previously reset state */
#define WD_T110                 0x02    /* Temperature overheat sense */
#define WD_HRTBT                0x04    /* Heartbeat sense */
#define WD_RLY2                 0x08    /* External relay triggered */
#define WD_SRLY2                0x80    /* Software external relay triggered */
/* Port 1 : Control Status #1 for the PC Watchdog card, revision C. */
#define WD_REVC_WTRP            0x01    /* Watchdog Trip status */
#define WD_REVC_HRBT            0x02    /* Watchdog Heartbeat */
#define WD_REVC_TTRP            0x04    /* Temperature Trip status */
#define WD_REVC_RL2A            0x08    /* Relay 2 activated by
                                                        on-board processor */
#define WD_REVC_RL1A            0x10    /* Relay 1 active */
#define WD_REVC_R2DS            0x40    /* Relay 2 disable */
#define WD_REVC_RLY2            0x80    /* Relay 2 activated? */
/* Port 2 : Control Status #2 */
#define WD_WDIS                 0x10    /* Watchdog Disabled */
#define WD_ENTP                 0x20    /* Watchdog Enable Temperature Trip */
#define WD_SSEL                 0x40    /* Watchdog Switch Select
                                                        (1:SW1 <-> 0:SW2) */
#define WD_WCMD                 0x80    /* Watchdog Command Mode */

/* max. time we give an ISA watchdog card to process a command */
/* 500ms for each 4 bit response (according to spec.) */
#define ISA_COMMAND_TIMEOUT     1000

/* Watchdog's internal commands */
#define CMD_ISA_IDLE                    0x00
#define CMD_ISA_VERSION_INTEGER         0x01
#define CMD_ISA_VERSION_TENTH           0x02
#define CMD_ISA_VERSION_HUNDRETH        0x03
#define CMD_ISA_VERSION_MINOR           0x04
#define CMD_ISA_SWITCH_SETTINGS         0x05
#define CMD_ISA_RESET_PC                0x06
#define CMD_ISA_ARM_0                   0x07
#define CMD_ISA_ARM_30                  0x08
#define CMD_ISA_ARM_60                  0x09
#define CMD_ISA_DELAY_TIME_2SECS        0x0A
#define CMD_ISA_DELAY_TIME_4SECS        0x0B
#define CMD_ISA_DELAY_TIME_8SECS        0x0C
#define CMD_ISA_RESET_RELAYS            0x0D

/* Watchdog's Dip Switch heartbeat values */
static const int heartbeat_tbl[] = {
        20,     /* OFF-OFF-OFF  = 20 Sec  */
        40,     /* OFF-OFF-ON   = 40 Sec  */
        60,     /* OFF-ON-OFF   =  1 Min  */
        300,    /* OFF-ON-ON    =  5 Min  */
        600,    /* ON-OFF-OFF   = 10 Min  */
        1800,   /* ON-OFF-ON    = 30 Min  */
        3600,   /* ON-ON-OFF    =  1 Hour */
        7200,   /* ON-ON-ON     =  2 hour */
};

/*
 * We are using an kernel timer to do the pinging of the watchdog
 * every ~500ms. We try to set the internal heartbeat of the
 * watchdog to 2 ms.
 */

#define WDT_INTERVAL (HZ/2+1)

/* We can only use 1 card due to the /dev/watchdog restriction */
static int cards_found;

/* internal variables */
static unsigned long open_allowed;
static char expect_close;
static int temp_panic;

/* this is private data for each ISA-PC watchdog card */
static struct {
        char fw_ver_str[6];             /* The cards firmware version */
        int revision;                   /* The card's revision */
        int supports_temp;              /* Whether or not the card has
                                                a temperature device */
        int command_mode;               /* Whether or not the card is in
                                                command mode */
        int boot_status;                /* The card's boot status */
        int io_addr;                    /* The cards I/O address */
        spinlock_t io_lock;             /* the lock for io operations */
        struct timer_list timer;        /* The timer that pings the watchdog */
        unsigned long next_heartbeat;   /* the next_heartbeat for the timer */
} pcwd_private;

/* module parameters */
#define QUIET   0       /* Default */
#define VERBOSE 1       /* Verbose */
#define DEBUG   2       /* print fancy stuff too */
static int debug = QUIET;
module_param(debug, int, 0);
MODULE_PARM_DESC(debug,
                "Debug level: 0=Quiet, 1=Verbose, 2=Debug (default=0)");

/* default heartbeat = delay-time from dip-switches */
#define WATCHDOG_HEARTBEAT 0
static int heartbeat = WATCHDOG_HEARTBEAT;
module_param(heartbeat, int, 0);
MODULE_PARM_DESC(heartbeat, "Watchdog heartbeat in seconds. "
        "(2 <= heartbeat <= 7200 or 0=delay-time from dip-switches, default="
                                __MODULE_STRING(WATCHDOG_HEARTBEAT) ")");

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) ")");

/*
 *      Internal functions
 */

static int send_isa_command(int cmd)
{
        int i;
        int control_status;
        int port0, last_port0;  /* Double read for stabilising */

        if (debug >= DEBUG)
                printk(KERN_DEBUG PFX "sending following data cmd=0x%02x\n",
                        cmd);

        /* The WCMD bit must be 1 and the command is only 4 bits in size */
        control_status = (cmd & 0x0F) | WD_WCMD;
        outb_p(control_status, pcwd_private.io_addr + 2);
        udelay(ISA_COMMAND_TIMEOUT);

        port0 = inb_p(pcwd_private.io_addr);
        for (i = 0; i < 25; ++i) {
                last_port0 = port0;
                port0 = inb_p(pcwd_private.io_addr);

                if (port0 == last_port0)
                        break;  /* Data is stable */

                udelay(250);
        }

        if (debug >= DEBUG)
                printk(KERN_DEBUG PFX "received following data for "
                        "cmd=0x%02x: port0=0x%02x last_port0=0x%02x\n",
                        cmd, port0, last_port0);

        return port0;
}

static int set_command_mode(void)
{
        int i, found = 0, count = 0;

        /* Set the card into command mode */
        spin_lock(&pcwd_private.io_lock);
        while ((!found) && (count < 3)) {
                i = send_isa_command(CMD_ISA_IDLE);

                if (i == 0x00)
                        found = 1;
                else if (i == 0xF3) {
                        /* Card does not like what we've done to it */
                        outb_p(0x00, pcwd_private.io_addr + 2);
                        udelay(1200);   /* Spec says wait 1ms */
                        outb_p(0x00, pcwd_private.io_addr + 2);
                        udelay(ISA_COMMAND_TIMEOUT);
                }
                count++;
        }
        spin_unlock(&pcwd_private.io_lock);
        pcwd_private.command_mode = found;

        if (debug >= DEBUG)
                printk(KERN_DEBUG PFX "command_mode=%d\n",
                                pcwd_private.command_mode);

        return found;
}

static void unset_command_mode(void)
{
        /* Set the card into normal mode */
        spin_lock(&pcwd_private.io_lock);
        outb_p(0x00, pcwd_private.io_addr + 2);
        udelay(ISA_COMMAND_TIMEOUT);
        spin_unlock(&pcwd_private.io_lock);

        pcwd_private.command_mode = 0;

        if (debug >= DEBUG)
                printk(KERN_DEBUG PFX "command_mode=%d\n",
                                pcwd_private.command_mode);
}

static inline void pcwd_check_temperature_support(void)
{
        if (inb(pcwd_private.io_addr) != 0xF0)
                pcwd_private.supports_temp = 1;
}

static inline void pcwd_get_firmware(void)
{
        int one, ten, hund, minor;

        strcpy(pcwd_private.fw_ver_str, "ERROR");

        if (set_command_mode()) {
                one = send_isa_command(CMD_ISA_VERSION_INTEGER);
                ten = send_isa_command(CMD_ISA_VERSION_TENTH);
                hund = send_isa_command(CMD_ISA_VERSION_HUNDRETH);
                minor = send_isa_command(CMD_ISA_VERSION_MINOR);
                sprintf(pcwd_private.fw_ver_str, "%c.%c%c%c",
                                        one, ten, hund, minor);
        }
        unset_command_mode();

        return;
}

static inline int pcwd_get_option_switches(void)
{
        int option_switches = 0;

        if (set_command_mode()) {
                /* Get switch settings */
                option_switches = send_isa_command(CMD_ISA_SWITCH_SETTINGS);
        }

        unset_command_mode();
        return option_switches;
}

static void pcwd_show_card_info(void)
{
        int option_switches;

        /* Get some extra info from the hardware (in command/debug/diag mode) */
        if (pcwd_private.revision == PCWD_REVISION_A)
                printk(KERN_INFO PFX
                        "ISA-PC Watchdog (REV.A) detected at port 0x%04x\n",
                                                        pcwd_private.io_addr);
        else if (pcwd_private.revision == PCWD_REVISION_C) {
                pcwd_get_firmware();
                printk(KERN_INFO PFX "ISA-PC Watchdog (REV.C) detected at port "
                        "0x%04x (Firmware version: %s)\n",
                        pcwd_private.io_addr, pcwd_private.fw_ver_str);
                option_switches = pcwd_get_option_switches();
                printk(KERN_INFO PFX "Option switches (0x%02x): "
                        "Temperature Reset Enable=%s, Power On Delay=%s\n",
                        option_switches,
                        ((option_switches & 0x10) ? "ON" : "OFF"),
                        ((option_switches & 0x08) ? "ON" : "OFF"));

                /* Reprogram internal heartbeat to 2 seconds */
                if (set_command_mode()) {
                        send_isa_command(CMD_ISA_DELAY_TIME_2SECS);
                        unset_command_mode();
                }
        }

        if (pcwd_private.supports_temp)
                printk(KERN_INFO PFX "Temperature Option Detected\n");

        if (pcwd_private.boot_status & WDIOF_CARDRESET)
                printk(KERN_INFO PFX
                        "Previous reboot was caused by the card\n");

        if (pcwd_private.boot_status & WDIOF_OVERHEAT) {
                printk(KERN_EMERG PFX
                        "Card senses a CPU Overheat. Panicking!\n");
                printk(KERN_EMERG PFX
                        "CPU Overheat\n");
        }

        if (pcwd_private.boot_status == 0)
                printk(KERN_INFO PFX
                        "No previous trip detected - Cold boot or reset\n");
}

static void pcwd_timer_ping(unsigned long data)
{
        int wdrst_stat;

        /* If we got a heartbeat pulse within the WDT_INTERVAL
         * we agree to ping the WDT */
        if (time_before(jiffies, pcwd_private.next_heartbeat)) {
                /* Ping the watchdog */
                spin_lock(&pcwd_private.io_lock);
                if (pcwd_private.revision == PCWD_REVISION_A) {
                        /*  Rev A cards are reset by setting the
                            WD_WDRST bit in register 1 */
                        wdrst_stat = inb_p(pcwd_private.io_addr);
                        wdrst_stat &= 0x0F;
                        wdrst_stat |= WD_WDRST;

                        outb_p(wdrst_stat, pcwd_private.io_addr + 1);
                } else {
                        /* Re-trigger watchdog by writing to port 0 */
                        outb_p(0x00, pcwd_private.io_addr);
                }

                /* Re-set the timer interval */
                mod_timer(&pcwd_private.timer, jiffies + WDT_INTERVAL);

                spin_unlock(&pcwd_private.io_lock);
        } else {
                printk(KERN_WARNING PFX
                        "Heartbeat lost! Will not ping the watchdog\n");
        }
}

static int pcwd_start(void)
{
        int stat_reg;

        pcwd_private.next_heartbeat = jiffies + (heartbeat * HZ);

        /* Start the timer */
        mod_timer(&pcwd_private.timer, jiffies + WDT_INTERVAL);

        /* Enable the port */
        if (pcwd_private.revision == PCWD_REVISION_C) {
                spin_lock(&pcwd_private.io_lock);
                outb_p(0x00, pcwd_private.io_addr + 3);
                udelay(ISA_COMMAND_TIMEOUT);
                stat_reg = inb_p(pcwd_private.io_addr + 2);
                spin_unlock(&pcwd_private.io_lock);
                if (stat_reg & WD_WDIS) {
                        printk(KERN_INFO PFX "Could not start watchdog\n");
                        return -EIO;
                }
        }

        if (debug >= VERBOSE)
                printk(KERN_DEBUG PFX "Watchdog started\n");

        return 0;
}

static int pcwd_stop(void)
{
        int stat_reg;

        /* Stop the timer */
        del_timer(&pcwd_private.timer);

        /*  Disable the board  */
        if (pcwd_private.revision == PCWD_REVISION_C) {
                spin_lock(&pcwd_private.io_lock);
                outb_p(0xA5, pcwd_private.io_addr + 3);
                udelay(ISA_COMMAND_TIMEOUT);
                outb_p(0xA5, pcwd_private.io_addr + 3);
                udelay(ISA_COMMAND_TIMEOUT);
                stat_reg = inb_p(pcwd_private.io_addr + 2);
                spin_unlock(&pcwd_private.io_lock);
                if ((stat_reg & WD_WDIS) == 0) {
                        printk(KERN_INFO PFX "Could not stop watchdog\n");
                        return -EIO;
                }
        }

        if (debug >= VERBOSE)
                printk(KERN_DEBUG PFX "Watchdog stopped\n");

        return 0;
}

static int pcwd_keepalive(void)
{
        /* user land ping */
        pcwd_private.next_heartbeat = jiffies + (heartbeat * HZ);

        if (debug >= DEBUG)
                printk(KERN_DEBUG PFX "Watchdog keepalive signal send\n");

        return 0;
}

static int pcwd_set_heartbeat(int t)
{
        if (t < 2 || t > 7200) /* arbitrary upper limit */
                return -EINVAL;

        heartbeat = t;

        if (debug >= VERBOSE)
                printk(KERN_DEBUG PFX "New heartbeat: %d\n",
                       heartbeat);

        return 0;
}

static int pcwd_get_status(int *status)
{
        int control_status;

        *status = 0;
        spin_lock(&pcwd_private.io_lock);
        if (pcwd_private.revision == PCWD_REVISION_A)
                /* Rev A cards return status information from
                 * the base register, which is used for the
                 * temperature in other cards. */
                control_status = inb(pcwd_private.io_addr);
        else {
                /* Rev C cards return card status in the base
                 * address + 1 register. And use different bits
                 * to indicate a card initiated reset, and an
                 * over-temperature condition. And the reboot
                 * status can be reset. */
                control_status = inb(pcwd_private.io_addr + 1);
        }
        spin_unlock(&pcwd_private.io_lock);

        if (pcwd_private.revision == PCWD_REVISION_A) {
                if (control_status & WD_WDRST)
                        *status |= WDIOF_CARDRESET;

                if (control_status & WD_T110) {
                        *status |= WDIOF_OVERHEAT;
                        if (temp_panic) {
                                printk(KERN_INFO PFX
                                        "Temperature overheat trip!\n");
                                kernel_power_off();
                        }
                }
        } else {
                if (control_status & WD_REVC_WTRP)
                        *status |= WDIOF_CARDRESET;

                if (control_status & WD_REVC_TTRP) {
                        *status |= WDIOF_OVERHEAT;
                        if (temp_panic) {
                                printk(KERN_INFO PFX
                                        "Temperature overheat trip!\n");
                                kernel_power_off();
                        }
                }
        }

        return 0;
}

static int pcwd_clear_status(void)
{
        int control_status;

        if (pcwd_private.revision == PCWD_REVISION_C) {
                spin_lock(&pcwd_private.io_lock);

                if (debug >= VERBOSE)
                        printk(KERN_INFO PFX
                                        "clearing watchdog trip status\n");

                control_status = inb_p(pcwd_private.io_addr + 1);

                if (debug >= DEBUG) {
                        printk(KERN_DEBUG PFX "status was: 0x%02x\n",
                                control_status);
                        printk(KERN_DEBUG PFX "sending: 0x%02x\n",
                                (control_status & WD_REVC_R2DS));
                }

                /* clear reset status & Keep Relay 2 disable state as it is */
                outb_p((control_status & WD_REVC_R2DS),
                                                pcwd_private.io_addr + 1);

                spin_unlock(&pcwd_private.io_lock);
        }
        return 0;
}

static int pcwd_get_temperature(int *temperature)
{
        /* check that port 0 gives temperature info and no command results */
        if (pcwd_private.command_mode)
                return -1;

        *temperature = 0;
        if (!pcwd_private.supports_temp)
                return -ENODEV;

        /*
         * Convert celsius to fahrenheit, since this was
         * the decided 'standard' for this return value.
         */
        spin_lock(&pcwd_private.io_lock);
        *temperature = ((inb(pcwd_private.io_addr)) * 9 / 5) + 32;
        spin_unlock(&pcwd_private.io_lock);

        if (debug >= DEBUG) {
                printk(KERN_DEBUG PFX "temperature is: %d F\n",
                        *temperature);
        }

        return 0;
}

/*
 *      /dev/watchdog handling
 */

static long pcwd_ioctl(struct file *file, unsigned int cmd, unsigned long arg)
{
        int rv;
        int status;
        int temperature;
        int new_heartbeat;
        int __user *argp = (int __user *)arg;
        static struct watchdog_info ident = {
                .options =              WDIOF_OVERHEAT |
                                        WDIOF_CARDRESET |
                                        WDIOF_KEEPALIVEPING |
                                        WDIOF_SETTIMEOUT |
                                        WDIOF_MAGICCLOSE,
                .firmware_version =     1,
                .identity =             "PCWD",
        };

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

        case WDIOC_GETSTATUS:
                pcwd_get_status(&status);
                return put_user(status, argp);

        case WDIOC_GETBOOTSTATUS:
                return put_user(pcwd_private.boot_status, argp);

        case WDIOC_GETTEMP:
                if (pcwd_get_temperature(&temperature))
                        return -EFAULT;

                return put_user(temperature, argp);

        case WDIOC_SETOPTIONS:
                if (pcwd_private.revision == PCWD_REVISION_C) {
                        if (get_user(rv, argp))
                                return -EFAULT;

                        if (rv & WDIOS_DISABLECARD) {
                                status = pcwd_stop();
                                if (status < 0)
                                        return status;
                        }
                        if (rv & WDIOS_ENABLECARD) {
                                status = pcwd_start();
                                if (status < 0)
                                        return status;
                        }
                        if (rv & WDIOS_TEMPPANIC)
                                temp_panic = 1;
                }
                return -EINVAL;

        case WDIOC_KEEPALIVE:
                pcwd_keepalive();
                return 0;

        case WDIOC_SETTIMEOUT:
                if (get_user(new_heartbeat, argp))
                        return -EFAULT;

                if (pcwd_set_heartbeat(new_heartbeat))
                        return -EINVAL;

                pcwd_keepalive();
                /* Fall */

        case WDIOC_GETTIMEOUT:
                return put_user(heartbeat, argp);

        default:
                return -ENOTTY;
        }

        return 0;
}

static ssize_t pcwd_write(struct file *file, const char __user *buf, size_t len,
                          loff_t *ppos)
{
        if (len) {
                if (!nowayout) {
                        size_t i;

                        /* In case it was set long ago */
                        expect_close = 0;

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

                                if (get_user(c, buf + i))
                                        return -EFAULT;
                                if (c == 'V')
                                        expect_close = 42;
                        }
                }
                pcwd_keepalive();
        }
        return len;
}

static int pcwd_open(struct inode *inode, struct file *file)
{
        if (test_and_set_bit(0, &open_allowed))
                return -EBUSY;
        if (nowayout)
                __module_get(THIS_MODULE);
        /* Activate */
        pcwd_start();
        pcwd_keepalive();
        return nonseekable_open(inode, file);
}

static int pcwd_close(struct inode *inode, struct file *file)
{
        if (expect_close == 42)
                pcwd_stop();
        else {
                printk(KERN_CRIT PFX
                        "Unexpected close, not stopping watchdog!\n");
                pcwd_keepalive();
        }
        expect_close = 0;
        clear_bit(0, &open_allowed);
        return 0;
}

/*
 *      /dev/temperature handling
 */

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

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

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

        return 1;
}

static int pcwd_temp_open(struct inode *inode, struct file *file)
{
        if (!pcwd_private.supports_temp)
                return -ENODEV;

        return nonseekable_open(inode, file);
}

static int pcwd_temp_close(struct inode *inode, struct file *file)
{
        return 0;
}

/*
 *      Kernel Interfaces
 */

static const struct file_operations pcwd_fops = {
        .owner          = THIS_MODULE,
        .llseek         = no_llseek,
        .write          = pcwd_write,
        .unlocked_ioctl = pcwd_ioctl,
        .open           = pcwd_open,
        .release        = pcwd_close,
};

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

static const struct file_operations pcwd_temp_fops = {
        .owner          = THIS_MODULE,
        .llseek         = no_llseek,
        .read           = pcwd_temp_read,
        .open           = pcwd_temp_open,
        .release        = pcwd_temp_close,
};

static struct miscdevice temp_miscdev = {
        .minor =        TEMP_MINOR,
        .name =         "temperature",
        .fops =         &pcwd_temp_fops,
};

/*
 *      Init & exit routines
 */

static inline int get_revision(void)
{
        int r = PCWD_REVISION_C;

        spin_lock(&pcwd_private.io_lock);
        /* REV A cards use only 2 io ports; test
         * presumes a floating bus reads as 0xff. */
        if ((inb(pcwd_private.io_addr + 2) == 0xFF) ||
            (inb(pcwd_private.io_addr + 3) == 0xFF))
                r = PCWD_REVISION_A;
        spin_unlock(&pcwd_private.io_lock);

        return r;
}

/*
 *  The ISA cards have a heartbeat bit in one of the registers, which
 *  register is card dependent.  The heartbeat bit is monitored, and if
 *  found, is considered proof that a Berkshire card has been found.
 *  The initial rate is once per second at board start up, then twice
 *  per second for normal operation.
 */
static int __devinit pcwd_isa_match(struct device *dev, unsigned int id)
{
        int base_addr = pcwd_ioports[id];
        int port0, last_port0;  /* Reg 0, in case it's REV A */
        int port1, last_port1;  /* Register 1 for REV C cards */
        int i;
        int retval;

        if (debug >= DEBUG)
                printk(KERN_DEBUG PFX "pcwd_isa_match id=%d\n",
                        id);

        if (!request_region(base_addr, 4, "PCWD")) {
                printk(KERN_INFO PFX "Port 0x%04x unavailable\n", base_addr);
                return 0;
        }

        retval = 0;

        port0 = inb_p(base_addr);       /* For REV A boards */
        port1 = inb_p(base_addr + 1);   /* For REV C boards */
        if (port0 != 0xff || port1 != 0xff) {
                /* Not an 'ff' from a floating bus, so must be a card! */
                for (i = 0; i < 4; ++i) {

                        msleep(500);

                        last_port0 = port0;
                        last_port1 = port1;

                        port0 = inb_p(base_addr);
                        port1 = inb_p(base_addr + 1);

                        /* Has either hearbeat bit changed?  */
                        if ((port0 ^ last_port0) & WD_HRTBT ||
                            (port1 ^ last_port1) & WD_REVC_HRBT) {
                                retval = 1;
                                break;
                        }
                }
        }
        release_region(base_addr, 4);

        return retval;
}

static int __devinit pcwd_isa_probe(struct device *dev, unsigned int id)
{
        int ret;

        if (debug >= DEBUG)
                printk(KERN_DEBUG PFX "pcwd_isa_probe id=%d\n",
                        id);

        cards_found++;
        if (cards_found == 1)
                printk(KERN_INFO PFX "v%s Ken Hollis (kenji@bitgate.com)\n",
                                                        WATCHDOG_VERSION);

        if (cards_found > 1) {
                printk(KERN_ERR PFX "This driver only supports 1 device\n");
                return -ENODEV;
        }

        if (pcwd_ioports[id] == 0x0000) {
                printk(KERN_ERR PFX "No I/O-Address for card detected\n");
                return -ENODEV;
        }
        pcwd_private.io_addr = pcwd_ioports[id];

        spin_lock_init(&pcwd_private.io_lock);

        /* Check card's revision */
        pcwd_private.revision = get_revision();

        if (!request_region(pcwd_private.io_addr,
                (pcwd_private.revision == PCWD_REVISION_A) ? 2 : 4, "PCWD")) {
                printk(KERN_ERR PFX "I/O address 0x%04x already in use\n",
                        pcwd_private.io_addr);
                ret = -EIO;
                goto error_request_region;
        }

        /* Initial variables */
        pcwd_private.supports_temp = 0;
        temp_panic = 0;
        pcwd_private.boot_status = 0x0000;

        /* get the boot_status */
        pcwd_get_status(&pcwd_private.boot_status);

        /* clear the "card caused reboot" flag */
        pcwd_clear_status();

        setup_timer(&pcwd_private.timer, pcwd_timer_ping, 0);

        /*  Disable the board  */
        pcwd_stop();

        /*  Check whether or not the card supports the temperature device */
        pcwd_check_temperature_support();

        /* Show info about the card itself */
        pcwd_show_card_info();

        /* If heartbeat = 0 then we use the heartbeat from the dip-switches */
        if (heartbeat == 0)
                heartbeat = heartbeat_tbl[(pcwd_get_option_switches() & 0x07)];

        /* Check that the heartbeat value is within it's range;
           if not reset to the default */
        if (pcwd_set_heartbeat(heartbeat)) {
                pcwd_set_heartbeat(WATCHDOG_HEARTBEAT);
                printk(KERN_INFO PFX
                  "heartbeat value must be 2 <= heartbeat <= 7200, using %d\n",
                                                        WATCHDOG_HEARTBEAT);
        }

        if (pcwd_private.supports_temp) {
                ret = misc_register(&temp_miscdev);
                if (ret) {
                        printk(KERN_ERR PFX
                            "cannot register miscdev on minor=%d (err=%d)\n",
                                                        TEMP_MINOR, ret);
                        goto error_misc_register_temp;
                }
        }

        ret = misc_register(&pcwd_miscdev);
        if (ret) {
                printk(KERN_ERR PFX
                        "cannot register miscdev on minor=%d (err=%d)\n",
                                        WATCHDOG_MINOR, ret);
                goto error_misc_register_watchdog;
        }

        printk(KERN_INFO PFX "initialized. heartbeat=%d sec (nowayout=%d)\n",
                heartbeat, nowayout);

        return 0;

error_misc_register_watchdog:
        if (pcwd_private.supports_temp)
                misc_deregister(&temp_miscdev);
error_misc_register_temp:
        release_region(pcwd_private.io_addr,
                        (pcwd_private.revision == PCWD_REVISION_A) ? 2 : 4);
error_request_region:
        pcwd_private.io_addr = 0x0000;
        cards_found--;
        return ret;
}

static int __devexit pcwd_isa_remove(struct device *dev, unsigned int id)
{
        if (debug >= DEBUG)
                printk(KERN_DEBUG PFX "pcwd_isa_remove id=%d\n",
                        id);

        if (!pcwd_private.io_addr)
                return 1;

        /*  Disable the board  */
        if (!nowayout)
                pcwd_stop();

        /* Deregister */
        misc_deregister(&pcwd_miscdev);
        if (pcwd_private.supports_temp)
                misc_deregister(&temp_miscdev);
        release_region(pcwd_private.io_addr,
                        (pcwd_private.revision == PCWD_REVISION_A) ? 2 : 4);
        pcwd_private.io_addr = 0x0000;
        cards_found--;

        return 0;
}

static void pcwd_isa_shutdown(struct device *dev, unsigned int id)

{
        if (debug >= DEBUG)
                printk(KERN_DEBUG PFX "pcwd_isa_shutdown id=%d\n",
                        id);

        pcwd_stop();
}

static struct isa_driver pcwd_isa_driver = {
        .match          = pcwd_isa_match,
        .probe          = pcwd_isa_probe,
        .remove         = __devexit_p(pcwd_isa_remove),
        .shutdown       = pcwd_isa_shutdown,
        .driver         = {
                .owner  = THIS_MODULE,
                .name   = WATCHDOG_NAME,
        },
};

static int __init pcwd_init_module(void)
{
        return isa_register_driver(&pcwd_isa_driver, PCWD_ISA_NR_CARDS);
}

static void __exit pcwd_cleanup_module(void)
{
        isa_unregister_driver(&pcwd_isa_driver);
        printk(KERN_INFO PFX "Watchdog Module Unloaded.\n");
}

module_init(pcwd_init_module);
module_exit(pcwd_cleanup_module);

MODULE_AUTHOR("Ken Hollis <kenji@bitgate.com>, "
                "Wim Van Sebroeck <wim@iguana.be>");
MODULE_DESCRIPTION("Berkshire ISA-PC Watchdog driver");
MODULE_VERSION(WATCHDOG_VERSION);
MODULE_LICENSE("GPL");
MODULE_ALIAS_MISCDEV(WATCHDOG_MINOR);
MODULE_ALIAS_MISCDEV(TEMP_MINOR);