/*
 *	Eurotech CPU-1220/1410 on board WDT driver for Linux 2.4.x
 *
 *	(c) Copyright 2001 Ascensit <support@ascensit.com>
 *	(c) Copyright 2001 Rodolfo Giometti <giometti@ascensit.com>
 *	(c) Copyright 2002 Rob Radez <rob@osinvestor.com>
 *
 *	Based on wdt.c.
 *	Original copyright messages:
 *
 *      (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>*
 */

/* Changelog:
 *
 * 2002/04/25 - Rob Radez
 *	clean up #includes
 *	clean up locking
 *	make __setup param unique
 *	proper options in watchdog_info
 *	add WDIOC_GETSTATUS and WDIOC_SETOPTIONS ioctls
 *	add expect_close support
 *
 * 2001 - Rodolfo Giometti
 *	Initial release
 *
 * 2002.05.30 - Joel Becker <joel.becker@oracle.com>
 * 	Added Matt Domsch's nowayout module option.
 */

#include <linux/config.h>
#include <linux/module.h>
#include <linux/types.h>
#include <linux/errno.h>
#include <linux/kernel.h>
#include <linux/miscdevice.h>
#include <linux/watchdog.h>
#include <linux/ioport.h>
#include <linux/fcntl.h>
#include <asm/io.h>
#include <asm/uaccess.h>
#include <asm/system.h>
#include <linux/notifier.h>
#include <linux/reboot.h>
#include <linux/init.h>

static unsigned long eurwdt_is_open;
static int eurwdt_timeout;
static char eur_expect_close;
 
/*
 *      You must set these - there is no sane way to probe for this board.
 *      You can use wdt=x,y to set these now.
 */
 
static int io = 0x3f0;
static int irq = 10;
static char *ev = "int";
 
#define WDT_TIMEOUT		60                /* 1 minute */

#ifdef CONFIG_WATCHDOG_NOWAYOUT
static int nowayout = 1;
#else
static int nowayout = 0;
#endif

MODULE_PARM(nowayout,"i");
MODULE_PARM_DESC(nowayout, "Watchdog cannot be stopped once started (default=CONFIG_WATCHDOG_NOWAYOUT)");

/*
 * Some symbolic names 
 */

#define WDT_CTRL_REG		0x30
#define WDT_OUTPIN_CFG		0xe2
   #define WDT_EVENT_INT	   0x00
   #define WDT_EVENT_REBOOT	   0x08
#define WDT_UNIT_SEL		0xf1
   #define WDT_UNIT_SECS	   0x80
#define WDT_TIMEOUT_VAL		0xf2
#define WDT_TIMER_CFG		0xf3
 

#ifndef MODULE

/**
 *      eurwdt_setup:
 *      @str: command line string
 *
 *      Setup options. The board isn't really probe-able so we have to
 *      get the user to tell us the configuration. Sane people build it
 *      modular but the others come here.
 */
 
static int __init eurwdt_setup(char *str)
{
   int ints[4];
 
   str = get_options (str, ARRAY_SIZE(ints), ints);
 
   if (ints[0] > 0) {
      io = ints[1];
      if (ints[0] > 1)
         irq = ints[2];
   }
 
   return 1;
}
 
__setup("eurwdt=", eurwdt_setup);

#endif /* !MODULE */
 
MODULE_PARM(io, "i");
MODULE_PARM_DESC(io, "Eurotech WDT io port (default=0x3f0)");
MODULE_PARM(irq, "i");
MODULE_PARM_DESC(irq, "Eurotech WDT irq (default=10)");
MODULE_PARM(ev, "s");
MODULE_PARM_DESC(ev, "Eurotech WDT event type (default is `int')");


/*
 *      Programming support
 */

static inline void eurwdt_write_reg(u8 index, u8 data)
{
	outb(index, io);
	outb(data, io+1);
}

static inline void eurwdt_lock_chip(void)
{
	outb(0xaa, io);
}

static inline void eurwdt_unlock_chip(void)
{
	outb(0x55, io);
	eurwdt_write_reg(0x07, 0x08);   /* set the logical device */
}

static inline void eurwdt_set_timeout(int timeout)
{
	eurwdt_write_reg(WDT_TIMEOUT_VAL, (u8) timeout);
}

static inline void eurwdt_disable_timer(void)
{
	eurwdt_set_timeout(0);
}
 
static void eurwdt_activate_timer(void)
{
	eurwdt_disable_timer();
	eurwdt_write_reg(WDT_CTRL_REG, 0x01);      /* activate the WDT */
	eurwdt_write_reg(WDT_OUTPIN_CFG, !strcmp("int", ev) ?
                                    WDT_EVENT_INT : WDT_EVENT_REBOOT);
	/* Setting interrupt line */
	if (irq == 2 || irq > 15 || irq < 0) {
		printk(KERN_ERR ": invalid irq number\n");
		irq = 0;   /* if invalid we disable interrupt */
	}
	if (irq == 0)
		printk(KERN_INFO ": interrupt disabled\n");
	eurwdt_write_reg(WDT_TIMER_CFG, irq<<4);

	eurwdt_write_reg(WDT_UNIT_SEL, WDT_UNIT_SECS);   /* we use seconds */
	eurwdt_set_timeout(0);                           /* the default timeout */ 
}


/*
 *      Kernel methods.
 */
 
void eurwdt_interrupt(int irq, void *dev_id, struct pt_regs *regs)
{
	printk(KERN_CRIT "timeout WDT timeout\n");
 
#ifdef ONLY_TESTING
	printk(KERN_CRIT "Would Reboot.\n");
#else
	printk(KERN_CRIT "Initiating system reboot.\n");
	machine_restart(NULL);
#endif
}


/**
 *      eurwdt_ping:
 *
 *      Reload counter one with the watchdog timeout.
 */
 
static void eurwdt_ping(void)
{
	/* Write the watchdog default value */
	eurwdt_set_timeout(eurwdt_timeout);
}
 
/**
 *      eurwdt_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 eurwdt_write(struct file *file, const char *buf, size_t count, loff_t *ppos)
{
	/*  Can't seek (pwrite) on this device  */
	if (ppos != &file->f_pos)
		return -ESPIPE;
 
	if (count) {
		if (!nowayout) {
			size_t i;

			eur_expect_close = 0;

			for (i = 0; i != count; i++) {
				char c;
				if(get_user(c, buf+i))
					return -EFAULT;
				if (c == 'V')
					eur_expect_close = 42;
			}
		}
		eurwdt_ping();   /* the default timeout */
	}
	return count;
}

/**
 *      eurwdt_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.
 */
 
static int eurwdt_ioctl(struct inode *inode, struct file *file,
        unsigned int cmd, unsigned long arg)
{
	static struct watchdog_info ident = {
		options		: WDIOF_KEEPALIVEPING | WDIOF_SETTIMEOUT | WDIOF_MAGICCLOSE,
		firmware_version	: 0,
		identity		: "WDT Eurotech CPU-1220/1410"
	};
	int time;
 
	switch(cmd) {
		default:
			return -ENOTTY;
		case WDIOC_GETSUPPORT:
			return copy_to_user((struct watchdog_info *)arg, &ident, sizeof(ident)) ? -EFAULT : 0;
		case WDIOC_GETSTATUS:
		case WDIOC_GETBOOTSTATUS:
			return put_user(0, (int *) arg);
		case WDIOC_KEEPALIVE:
			eurwdt_ping();
			return 0;
		case WDIOC_SETTIMEOUT:
			if (copy_from_user(&time, (int *) arg, sizeof(int)))
				return -EFAULT;
			/* Sanity check */
			if (time < 0 || time > 255)
				return -EINVAL;
			eurwdt_timeout = time; 
			eurwdt_set_timeout(time); 
			/* Fall */
		case WDIOC_GETTIMEOUT:
			return put_user(eurwdt_timeout, (int *)arg);
		case WDIOC_SETOPTIONS:
		{
			int options, retval = -EINVAL;

			if (get_user(options, (int *)arg))
				return -EFAULT;
			if (options & WDIOS_DISABLECARD) {
				eurwdt_disable_timer();
				retval = 0;
			}

			if (options & WDIOS_ENABLECARD) {
				eurwdt_activate_timer();
				eurwdt_ping();
				retval = 0;
			}
			return retval;
		}
	}
}

/**
 *      eurwdt_open:
 *      @inode: inode of device
 *      @file: file handle to device
 *
 *      The misc device has been opened. The watchdog device is single
 *      open and on opening we load the counter.
 */
 
static int eurwdt_open(struct inode *inode, struct file *file)
{
	if (test_and_set_bit(0, &eurwdt_is_open))
		return -EBUSY;

	eurwdt_timeout = WDT_TIMEOUT;   /* initial timeout */

	/* Activate the WDT */
	eurwdt_activate_timer(); 

	return 0;
}
 
/**
 *      eurwdt_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 eurwdt_release(struct inode *inode, struct file *file)
{
	if (eur_expect_close == 42) {
		eurwdt_disable_timer();
	} else {
		printk(KERN_CRIT "eurwdt: Unexpected close, not stopping watchdog!\n");
		eurwdt_ping();
	}
	clear_bit(0, &eurwdt_is_open);
	eur_expect_close = 0;
	return 0;
}
 
/**
 *      eurwdt_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 eurwdt_notify_sys(struct notifier_block *this, unsigned long code,
        void *unused)
{
	if (code == SYS_DOWN || code == SYS_HALT) {
		/* Turn the card off */
		eurwdt_disable_timer();
	}
	return NOTIFY_DONE;
}
 
/*
 *      Kernel Interfaces
 */
 
 
static struct file_operations eurwdt_fops = {
        owner:          THIS_MODULE,
        llseek:         no_llseek,
        write:          eurwdt_write,
        ioctl:          eurwdt_ioctl,
        open:           eurwdt_open,
        release:        eurwdt_release,
};

static struct miscdevice eurwdt_miscdev =
{
        minor:		WATCHDOG_MINOR,
        name:		"watchdog",
        fops:		&eurwdt_fops,
};
 
/*
 *      The WDT card needs to learn about soft shutdowns in order to
 *      turn the timebomb registers off.
 */
 
static struct notifier_block eurwdt_notifier =
{
        eurwdt_notify_sys,
        NULL,
        0
};
 
/**
 *      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 eurwdt_exit(void)
{
	eurwdt_lock_chip();
	misc_deregister(&eurwdt_miscdev);
	unregister_reboot_notifier(&eurwdt_notifier);
	release_region(io, 2);
	free_irq(irq, NULL);
}
 
/**
 *      eurwdt_init:
 *
 *      Set up the WDT watchdog board. After grabbing the resources 
 *      we require we need also to unlock the device.
 *      The open() function will actually kick the board off.
 */
 
static int __init eurwdt_init(void)
{
	int ret;
 
	ret = misc_register(&eurwdt_miscdev);
	if (ret) {
		printk(KERN_ERR "eurwdt: can't misc_register on minor=%d\n", WATCHDOG_MINOR);
		goto out;
	}
	ret = request_irq(irq, eurwdt_interrupt, SA_INTERRUPT, "eurwdt", NULL);
	if(ret) {
		printk(KERN_ERR "eurwdt: IRQ %d is not free.\n", irq);
		goto outmisc;
	}

	if (!request_region(io, 2, "eurwdt")) {
		printk(KERN_ERR "eurwdt: IO %X is not free.\n", io);
		ret = -EBUSY;
		goto outirq;
	}

	ret = register_reboot_notifier(&eurwdt_notifier);
	if (ret) {
		printk(KERN_ERR "eurwdt: can't register reboot notifier (err=%d)\n", ret);
		goto outreg;
	}
	eurwdt_unlock_chip();
 
	ret = 0;
	printk(KERN_INFO "Eurotech WDT driver 0.01 at %X (Interrupt %d)"
                    " - timeout event: %s\n",  io, irq, (!strcmp("int", ev) ? "int" : "reboot"));
	return ret;
outreg:
	release_region(io, 2);
outirq:
	free_irq(irq, NULL);
outmisc:
	misc_deregister(&eurwdt_miscdev);
out:
	return ret;
}
 
module_init(eurwdt_init);
module_exit(eurwdt_exit);
 
MODULE_AUTHOR("Rodolfo Giometti");
MODULE_DESCRIPTION("Driver for Eurotech CPU-1220/1410 on board watchdog");
MODULE_LICENSE("GPL");
EXPORT_NO_SYMBOLS;