/*
   * 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/

   */

  #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt

  #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 struct miscdevice */

  #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 DRIVER_VERSION WATCHDOG_DRIVER_NAME " driver, v" WATCHDOG_VERSION "
  "

  
  /*
   * 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 bool nowayout = WATCHDOG_NOWAYOUT;
  module_param(nowayout, bool, 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)

  		pr_debug("sending following data cmd=0x%02x
  ", 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)

  		pr_debug("received following data for cmd=0x%02x: port0=0x%02x last_port0=0x%02x
  ",
  			 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)

  		pr_debug("command_mode=%d
  ", 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)

  		pr_debug("command_mode=%d
  ", 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)

  		pr_info("ISA-PC Watchdog (REV.A) detected at port 0x%04x
  ",
  			pcwd_private.io_addr);

  	else if (pcwd_private.revision == PCWD_REVISION_C) {

  		pcwd_get_firmware();

  		pr_info("ISA-PC Watchdog (REV.C) detected at port 0x%04x (Firmware version: %s)
  ",

  			pcwd_private.io_addr, pcwd_private.fw_ver_str);

  		option_switches = pcwd_get_option_switches();

  		pr_info("Option switches (0x%02x): Temperature Reset Enable=%s, Power On Delay=%s
  ",

  			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)

  		pr_info("Temperature Option Detected
  ");

  
  	if (pcwd_private.boot_status & WDIOF_CARDRESET)

  		pr_info("Previous reboot was caused by the card
  ");

  
  	if (pcwd_private.boot_status & WDIOF_OVERHEAT) {

  		pr_emerg("Card senses a CPU Overheat. Panicking!
  ");
  		pr_emerg("CPU Overheat
  ");

  	}
  
  	if (pcwd_private.boot_status == 0)

  		pr_info("No previous trip detected - Cold boot or reset
  ");

  }

  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 {

  		pr_warn("Heartbeat lost! Will not ping the watchdog
  ");

  	}
  }
  
  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) {

  			pr_info("Could not start watchdog
  ");

  			return -EIO;
  		}
  	}

  
  	if (debug >= VERBOSE)

  		pr_debug("Watchdog started
  ");

  	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) {

  			pr_info("Could not stop watchdog
  ");

  			return -EIO;
  		}
  	}

  
  	if (debug >= VERBOSE)

  		pr_debug("Watchdog stopped
  ");

  	return 0;
  }
  
  static int pcwd_keepalive(void)
  {
  	/* user land ping */

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

  
  	if (debug >= DEBUG)

  		pr_debug("Watchdog keepalive signal send
  ");

  	return 0;
  }
  
  static int pcwd_set_heartbeat(int t)
  {

  	if (t < 2 || t > 7200) /* arbitrary upper limit */

  		return -EINVAL;
  
  	heartbeat = t;

  
  	if (debug >= VERBOSE)

  		pr_debug("New heartbeat: %d
  ", 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) {

  				pr_info("Temperature overheat trip!
  ");

  				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) {

  				pr_info("Temperature overheat trip!
  ");

  				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)

  			pr_info("clearing watchdog trip status
  ");

  		control_status = inb_p(pcwd_private.io_addr + 1);

  		if (debug >= DEBUG) {

  			pr_debug("status was: 0x%02x
  ", control_status);
  			pr_debug("sending: 0x%02x
  ",
  				 (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) {

  		pr_debug("temperature is: %d F
  ", *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 const 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 {

  		pr_crit("Unexpected close, not stopping watchdog!
  ");

  		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 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)

  		pr_debug("pcwd_isa_match id=%d
  ", id);

  	if (!request_region(base_addr, 4, "PCWD")) {

  		pr_info("Port 0x%04x unavailable
  ", 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 pcwd_isa_probe(struct device *dev, unsigned int id)

  {
  	int ret;

  	if (debug >= DEBUG)

  		pr_debug("pcwd_isa_probe id=%d
  ", id);

  	cards_found++;
  	if (cards_found == 1)

  		pr_info("v%s Ken Hollis (kenji@bitgate.com)
  ",

  							WATCHDOG_VERSION);

  
  	if (cards_found > 1) {

  		pr_err("This driver only supports 1 device
  ");

  		return -ENODEV;
  	}

  	if (pcwd_ioports[id] == 0x0000) {

  		pr_err("No I/O-Address for card detected
  ");

  		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")) {

  		pr_err("I/O address 0x%04x already in use
  ",
  		       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);

  		pr_info("heartbeat value must be 2 <= heartbeat <= 7200, using %d
  ",
  			WATCHDOG_HEARTBEAT);

  	}

  	if (pcwd_private.supports_temp) {

  		ret = misc_register(&temp_miscdev);
  		if (ret) {

  			pr_err("cannot register miscdev on minor=%d (err=%d)
  ",
  			       TEMP_MINOR, ret);

  			goto error_misc_register_temp;

  		}
  	}
  
  	ret = misc_register(&pcwd_miscdev);
  	if (ret) {

  		pr_err("cannot register miscdev on minor=%d (err=%d)
  ",
  		       WATCHDOG_MINOR, ret);

  		goto error_misc_register_watchdog;

  	}

  	pr_info("initialized. heartbeat=%d sec (nowayout=%d)
  ",

  		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 pcwd_isa_remove(struct device *dev, unsigned int id)

  {

  	if (debug >= DEBUG)

  		pr_debug("pcwd_isa_remove id=%d
  ", 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)

  		pr_debug("pcwd_isa_shutdown id=%d
  ", id);

  	pcwd_stop();

  }

  static struct isa_driver pcwd_isa_driver = {
  	.match		= pcwd_isa_match,
  	.probe		= pcwd_isa_probe,

  	.remove		= 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);

  	pr_info("Watchdog Module Unloaded
  ");

  }
  
  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");