/*
   *      NS pc87413-wdt Watchdog Timer driver for Linux 2.6.x.x
   *

   *      This code is based on wdt.c with original copyright.

   *

   *      (C) Copyright 2006 Sven Anders, <anders@anduras.de>
   *                     and Marcus Junker, <junker@anduras.de>

   *
   *      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 Sven Anders, Marcus Junker nor ANDURAS AG

   *      admit liability nor provide warranty for any of this software.
   *      This material is provided "AS-IS" and at no charge.
   *

   *      Release 1.1

   */

  #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt

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

  #include <linux/io.h>
  #include <linux/uaccess.h>

  /* #define DEBUG 1 */

  #define DEFAULT_TIMEOUT     1		/* 1 minute */

  #define MAX_TIMEOUT         255

  #define VERSION             "1.1"
  #define MODNAME             "pc87413 WDT"

  #define DPFX                MODNAME " - DEBUG: "

  #define WDT_INDEX_IO_PORT   (io+0)	/* I/O port base (index register) */

  #define WDT_DATA_IO_PORT    (WDT_INDEX_IO_PORT+1)
  #define SWC_LDN             0x04

  #define SIOCFG2             0x22	/* Serial IO register */

  #define WDCTL               0x10	/* Watchdog-Timer-Control-Register */

  #define WDTO                0x11	/* Watchdog timeout register */
  #define WDCFG               0x12	/* Watchdog config register */

  #define IO_DEFAULT	0x2E		/* Address used on Portwell Boards */
  
  static int io = IO_DEFAULT;

  static int swc_base_addr = -1;

  static int timeout = DEFAULT_TIMEOUT;	/* timeout value */

  static unsigned long timer_enabled;	/* is the timer enabled? */

  static char expect_close;		/* is the close expected? */

  static DEFINE_SPINLOCK(io_lock);	/* to guard us from io races */

  static bool nowayout = WATCHDOG_NOWAYOUT;

  /* -- Low level function ----------------------------------------*/

  /* Select pins for Watchdog output */

  static inline void pc87413_select_wdt_out(void)

  {

  	unsigned int cr_data = 0;

  	/* Step 1: Select multiple pin,pin55,as WDT output */

  
  	outb_p(SIOCFG2, WDT_INDEX_IO_PORT);

  	cr_data = inb(WDT_DATA_IO_PORT);

  
  	cr_data |= 0x80; /* Set Bit7 to 1*/
  	outb_p(SIOCFG2, WDT_INDEX_IO_PORT);
  
  	outb_p(cr_data, WDT_DATA_IO_PORT);

  #ifdef DEBUG

  	pr_info(DPFX

  		"Select multiple pin,pin55,as WDT output: Bit7 to 1: %d
  ",
  								cr_data);

  #endif

  }

  /* Enable SWC functions */

  static inline void pc87413_enable_swc(void)
  {

  	unsigned int cr_data = 0;

  
  	/* Step 2: Enable SWC functions */

  	outb_p(0x07, WDT_INDEX_IO_PORT);	/* Point SWC_LDN (LDN=4) */

  	outb_p(SWC_LDN, WDT_DATA_IO_PORT);

  	outb_p(0x30, WDT_INDEX_IO_PORT);	/* Read Index 0x30 First */

  	cr_data = inb(WDT_DATA_IO_PORT);

  	cr_data |= 0x01;			/* Set Bit0 to 1 */

  	outb_p(0x30, WDT_INDEX_IO_PORT);

  	outb_p(cr_data, WDT_DATA_IO_PORT);	/* Index0x30_bit0P1 */

  #ifdef DEBUG

  	pr_info(DPFX "pc87413 - Enable SWC functions
  ");

  #endif

  }

  /* Read SWC I/O base address */

  static void pc87413_get_swc_base_addr(void)

  {

  	unsigned char addr_l, addr_h = 0;

  
  	/* Step 3: Read SWC I/O Base Address */

  	outb_p(0x60, WDT_INDEX_IO_PORT);	/* Read Index 0x60 */

  	addr_h = inb(WDT_DATA_IO_PORT);

  	outb_p(0x61, WDT_INDEX_IO_PORT);	/* Read Index 0x61 */

  	addr_l = inb(WDT_DATA_IO_PORT);

  
  	swc_base_addr = (addr_h << 8) + addr_l;

  #ifdef DEBUG

  	pr_info(DPFX

  		"Read SWC I/O Base Address: low %d, high %d, res %d
  ",
  						addr_l, addr_h, swc_base_addr);

  #endif

  }

  /* Select Bank 3 of SWC */

  static inline void pc87413_swc_bank3(void)

  {
  	/* Step 4: Select Bank3 of SWC */

  	outb_p(inb(swc_base_addr + 0x0f) | 0x03, swc_base_addr + 0x0f);

  #ifdef DEBUG

  	pr_info(DPFX "Select Bank3 of SWC
  ");

  #endif

  }

  /* Set watchdog timeout to x minutes */

  static inline void pc87413_programm_wdto(char pc87413_time)

  {
  	/* Step 5: Programm WDTO, Twd. */

  	outb_p(pc87413_time, swc_base_addr + WDTO);

  #ifdef DEBUG

  	pr_info(DPFX "Set WDTO to %d minutes
  ", pc87413_time);

  #endif

  }

  /* Enable WDEN */

  static inline void pc87413_enable_wden(void)

  {
  	/* Step 6: Enable WDEN */

  	outb_p(inb(swc_base_addr + WDCTL) | 0x01, swc_base_addr + WDCTL);

  #ifdef DEBUG

  	pr_info(DPFX "Enable WDEN
  ");

  #endif

  }

  /* Enable SW_WD_TREN */

  static inline void pc87413_enable_sw_wd_tren(void)

  {
  	/* Enable SW_WD_TREN */

  	outb_p(inb(swc_base_addr + WDCFG) | 0x80, swc_base_addr + WDCFG);

  #ifdef DEBUG

  	pr_info(DPFX "Enable SW_WD_TREN
  ");

  #endif

  }

  /* Disable SW_WD_TREN */

  static inline void pc87413_disable_sw_wd_tren(void)

  {
  	/* Disable SW_WD_TREN */

  	outb_p(inb(swc_base_addr + WDCFG) & 0x7f, swc_base_addr + WDCFG);

  #ifdef DEBUG

  	pr_info(DPFX "pc87413 - Disable SW_WD_TREN
  ");

  #endif

  }

  /* Enable SW_WD_TRG */

  static inline void pc87413_enable_sw_wd_trg(void)

  {

  	/* Enable SW_WD_TRG */

  	outb_p(inb(swc_base_addr + WDCTL) | 0x80, swc_base_addr + WDCTL);

  #ifdef DEBUG

  	pr_info(DPFX "pc87413 - Enable SW_WD_TRG
  ");

  #endif

  }

  /* Disable SW_WD_TRG */

  static inline void pc87413_disable_sw_wd_trg(void)

  {

  	/* Disable SW_WD_TRG */

  	outb_p(inb(swc_base_addr + WDCTL) & 0x7f, swc_base_addr + WDCTL);

  #ifdef DEBUG

  	pr_info(DPFX "Disable SW_WD_TRG
  ");

  #endif

  }

  /* -- Higher level functions ------------------------------------*/

  /* Enable the watchdog */

  static void pc87413_enable(void)

  {

  	spin_lock(&io_lock);

  	pc87413_swc_bank3();
  	pc87413_programm_wdto(timeout);
  	pc87413_enable_wden();
  	pc87413_enable_sw_wd_tren();
  	pc87413_enable_sw_wd_trg();

  
  	spin_unlock(&io_lock);

  }

  /* Disable the watchdog */

  static void pc87413_disable(void)

  {

  	spin_lock(&io_lock);

  	pc87413_swc_bank3();
  	pc87413_disable_sw_wd_tren();
  	pc87413_disable_sw_wd_trg();
  	pc87413_programm_wdto(0);

  
  	spin_unlock(&io_lock);

  }

  /* Refresh the watchdog */

  static void pc87413_refresh(void)

  {

  	spin_lock(&io_lock);

  	pc87413_swc_bank3();
  	pc87413_disable_sw_wd_tren();
  	pc87413_disable_sw_wd_trg();
  	pc87413_programm_wdto(timeout);
  	pc87413_enable_wden();
  	pc87413_enable_sw_wd_tren();
  	pc87413_enable_sw_wd_trg();

  	spin_unlock(&io_lock);

  }

  /* -- File operations -------------------------------------------*/
  
  /**
   *	pc87413_open:
   *	@inode: inode of device
   *	@file: file handle to device
   *
   */
  
  static int pc87413_open(struct inode *inode, struct file *file)
  {
  	/* /dev/watchdog can only be opened once */
  
  	if (test_and_set_bit(0, &timer_enabled))
  		return -EBUSY;
  
  	if (nowayout)
  		__module_get(THIS_MODULE);

  	/* Reload and activate timer */
  	pc87413_refresh();

  	pr_info("Watchdog enabled. Timeout set to %d minute(s).
  ", timeout);

  
  	return nonseekable_open(inode, file);
  }

  
  /**

   *	pc87413_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 pc87413_release(struct inode *inode, struct file *file)

  {

  	/* Shut off the timer. */
  
  	if (expect_close == 42) {
  		pc87413_disable();

  		pr_info("Watchdog disabled, sleeping again...
  ");

  	} else {

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

  		pc87413_refresh();
  	}

  	clear_bit(0, &timer_enabled);
  	expect_close = 0;

  	return 0;

  }

  /**
   *	pc87413_status:
   *
   *      return, if the watchdog is enabled (timeout is set...)
   */
  
  
  static int pc87413_status(void)

  {

  	  return 0; /* currently not supported */

  }
  
  /**
   *	pc87413_write:
   *	@file: file handle to the watchdog

   *	@data: data buffer to write
   *	@len: length in 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 pc87413_write(struct file *file, const char __user *data,
  			     size_t len, loff_t *ppos)

  {

  	/* See if we got the magic character 'V' and reload the timer */
  	if (len) {
  		if (!nowayout) {
  			size_t i;
  
  			/* reset expect flag */
  			expect_close = 0;

  			/* scan to see whether or not we got the
  			   magic character */

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

  				if (get_user(c, data + i))

  					return -EFAULT;
  				if (c == 'V')
  					expect_close = 42;
  			}
  		}
  
  		/* someone wrote to us, we should reload the timer */
  		pc87413_refresh();

  	}

  	return len;

  }

  /**

   *	pc87413_ioctl:

   *	@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 long pc87413_ioctl(struct file *file, unsigned int cmd,
  						unsigned long arg)

  {

  	int new_timeout;
  
  	union {
  		struct watchdog_info __user *ident;
  		int __user *i;
  	} uarg;

  	static const struct watchdog_info ident = {

  		.options          = WDIOF_KEEPALIVEPING |

  				    WDIOF_SETTIMEOUT |
  				    WDIOF_MAGICCLOSE,

  		.firmware_version = 1,

  		.identity         = "PC87413(HF/F) watchdog",

  	};

  	uarg.i = (int __user *)arg;

  	switch (cmd) {
  	case WDIOC_GETSUPPORT:
  		return copy_to_user(uarg.ident, &ident,
  					sizeof(ident)) ? -EFAULT : 0;
  	case WDIOC_GETSTATUS:
  		return put_user(pc87413_status(), uarg.i);
  	case WDIOC_GETBOOTSTATUS:
  		return put_user(0, uarg.i);

  	case WDIOC_SETOPTIONS:
  	{
  		int options, retval = -EINVAL;
  		if (get_user(options, uarg.i))
  			return -EFAULT;
  		if (options & WDIOS_DISABLECARD) {
  			pc87413_disable();
  			retval = 0;
  		}
  		if (options & WDIOS_ENABLECARD) {
  			pc87413_enable();
  			retval = 0;
  		}
  		return retval;
  	}

  	case WDIOC_KEEPALIVE:
  		pc87413_refresh();

  #ifdef DEBUG

  		pr_info(DPFX "keepalive
  ");

  #endif

  		return 0;
  	case WDIOC_SETTIMEOUT:
  		if (get_user(new_timeout, uarg.i))
  			return -EFAULT;
  		/* the API states this is given in secs */
  		new_timeout /= 60;
  		if (new_timeout < 0 || new_timeout > MAX_TIMEOUT)
  			return -EINVAL;
  		timeout = new_timeout;
  		pc87413_refresh();
  		/* fall through and return the new timeout... */
  	case WDIOC_GETTIMEOUT:
  		new_timeout = timeout * 60;
  		return put_user(new_timeout, uarg.i);

  	default:
  		return -ENOTTY;

  	}

  }

  /* -- Notifier funtions -----------------------------------------*/

  /**
   *	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 pc87413_notify_sys(struct notifier_block *this,
  			      unsigned long code,
  			      void *unused)

  {

  	if (code == SYS_DOWN || code == SYS_HALT)

  		/* Turn the card off */
  		pc87413_disable();

  	return NOTIFY_DONE;
  }

  /* -- Module's structures ---------------------------------------*/

  static const struct file_operations pc87413_fops = {

  	.owner		= THIS_MODULE,

  	.llseek		= no_llseek,

  	.write		= pc87413_write,

  	.unlocked_ioctl	= pc87413_ioctl,

  	.open		= pc87413_open,
  	.release	= pc87413_release,
  };

  static struct notifier_block pc87413_notifier = {

  	.notifier_call  = pc87413_notify_sys,

  };

  static struct miscdevice pc87413_miscdev = {

  	.minor          = WATCHDOG_MINOR,
  	.name           = "watchdog",

  	.fops           = &pc87413_fops,

  };

  /* -- Module init functions -------------------------------------*/

  
  /**

   *	pc87413_init: module's "constructor"

   *
   *	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 pc87413_init(void)

  {
  	int ret;

  	pr_info("Version " VERSION " at io 0x%X
  ",

  							WDT_INDEX_IO_PORT);

  	if (!request_muxed_region(io, 2, MODNAME))
  		return -EBUSY;

  	ret = register_reboot_notifier(&pc87413_notifier);

  	if (ret != 0)

  		pr_err("cannot register reboot notifier (err=%d)
  ", ret);

  	ret = misc_register(&pc87413_miscdev);

  	if (ret != 0) {

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

  		goto reboot_unreg;

  	}

  	pr_info("initialized. timeout=%d min
  ", timeout);

  
  	pc87413_select_wdt_out();
  	pc87413_enable_swc();
  	pc87413_get_swc_base_addr();
  
  	if (!request_region(swc_base_addr, 0x20, MODNAME)) {

  		pr_err("cannot request SWC region at 0x%x
  ", swc_base_addr);

  		ret = -EBUSY;
  		goto misc_unreg;
  	}

  	pc87413_enable();

  
  	release_region(io, 2);

  	return 0;

  
  misc_unreg:
  	misc_deregister(&pc87413_miscdev);
  reboot_unreg:
  	unregister_reboot_notifier(&pc87413_notifier);
  	release_region(io, 2);
  	return ret;

  }

  /**
   *	pc87413_exit: module's "destructor"
   *
   *	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 pc87413_exit(void)
  {
  	/* Stop the timer before we leave */

  	if (!nowayout) {

  		pc87413_disable();

  		pr_info("Watchdog disabled
  ");

  	}
  
  	misc_deregister(&pc87413_miscdev);
  	unregister_reboot_notifier(&pc87413_notifier);

  	release_region(swc_base_addr, 0x20);

  	pr_info("watchdog component driver removed
  ");

  }

  
  module_init(pc87413_init);
  module_exit(pc87413_exit);

  MODULE_AUTHOR("Sven Anders <anders@anduras.de>");
  MODULE_AUTHOR("Marcus Junker <junker@anduras.de>");

  MODULE_DESCRIPTION("PC87413 WDT driver");

  MODULE_LICENSE("GPL");

  module_param(io, int, 0);

  MODULE_PARM_DESC(io, MODNAME " I/O port (default: "
  					__MODULE_STRING(IO_DEFAULT) ").");

  
  module_param(timeout, int, 0);

  MODULE_PARM_DESC(timeout,
  		"Watchdog timeout in minutes (default="

  				__MODULE_STRING(DEFAULT_TIMEOUT) ").");

  module_param(nowayout, bool, 0);

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