/*
   * sma cpu5 watchdog driver
   *
   * Copyright (C) 2003 Heiko Ronsdorf <hero@ihg.uni-duisburg.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.
   *
   * This program is distributed in the hope that it will be useful,
   * but WITHOUT ANY WARRANTY; without even the implied warranty of
   * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
   * GNU General Public License for more details.
   *
   * You should have received a copy of the GNU General Public License
   * along with this program; if not, write to the Free Software
   * Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
   *
   */
  
  #include <linux/module.h>
  #include <linux/moduleparam.h>
  #include <linux/types.h>
  #include <linux/errno.h>
  #include <linux/miscdevice.h>
  #include <linux/fs.h>
  #include <linux/init.h>
  #include <linux/ioport.h>
  #include <linux/timer.h>

  #include <linux/completion.h>

  #include <linux/jiffies.h>

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

  #include <linux/watchdog.h>
  
  /* adjustable parameters */

  static int verbose;

  static int port = 0x91;
  static int ticks = 10000;

  static DEFINE_SPINLOCK(cpu5wdt_lock);

  
  #define PFX			"cpu5wdt: "
  
  #define CPU5WDT_EXTENT          0x0A
  
  #define CPU5WDT_STATUS_REG      0x00
  #define CPU5WDT_TIME_A_REG      0x02
  #define CPU5WDT_TIME_B_REG      0x03
  #define CPU5WDT_MODE_REG        0x04
  #define CPU5WDT_TRIGGER_REG     0x07
  #define CPU5WDT_ENABLE_REG      0x08
  #define CPU5WDT_RESET_REG       0x09
  
  #define CPU5WDT_INTERVAL	(HZ/10+1)
  
  /* some device data */
  
  static struct {

  	struct completion stop;

  	int running;

  	struct timer_list timer;

  	int queue;

  	int default_ticks;
  	unsigned long inuse;
  } cpu5wdt_device;
  
  /* generic helper functions */
  
  static void cpu5wdt_trigger(unsigned long unused)
  {

  	if (verbose > 2)

  		printk(KERN_DEBUG PFX "trigger at %i ticks
  ", ticks);

  	if (cpu5wdt_device.running)

  		ticks--;

  	spin_lock(&cpu5wdt_lock);

  	/* keep watchdog alive */
  	outb(1, port + CPU5WDT_TRIGGER_REG);
  
  	/* requeue?? */

  	if (cpu5wdt_device.queue && ticks)
  		mod_timer(&cpu5wdt_device.timer, jiffies + CPU5WDT_INTERVAL);

  	else {
  		/* ticks doesn't matter anyway */

  		complete(&cpu5wdt_device.stop);

  	}

  	spin_unlock(&cpu5wdt_lock);

  
  }
  
  static void cpu5wdt_reset(void)
  {
  	ticks = cpu5wdt_device.default_ticks;

  	if (verbose)

  		printk(KERN_DEBUG PFX "reset (%i ticks)
  ", (int) ticks);
  
  }
  
  static void cpu5wdt_start(void)
  {

  	unsigned long flags;
  
  	spin_lock_irqsave(&cpu5wdt_lock, flags);
  	if (!cpu5wdt_device.queue) {

  		cpu5wdt_device.queue = 1;
  		outb(0, port + CPU5WDT_TIME_A_REG);
  		outb(0, port + CPU5WDT_TIME_B_REG);
  		outb(1, port + CPU5WDT_MODE_REG);
  		outb(0, port + CPU5WDT_RESET_REG);
  		outb(0, port + CPU5WDT_ENABLE_REG);

  		mod_timer(&cpu5wdt_device.timer, jiffies + CPU5WDT_INTERVAL);

  	}
  	/* if process dies, counter is not decremented */
  	cpu5wdt_device.running++;

  	spin_unlock_irqrestore(&cpu5wdt_lock, flags);

  }
  
  static int cpu5wdt_stop(void)
  {

  	unsigned long flags;

  	spin_lock_irqsave(&cpu5wdt_lock, flags);
  	if (cpu5wdt_device.running)
  		cpu5wdt_device.running = 0;

  	ticks = cpu5wdt_device.default_ticks;

  	spin_unlock_irqrestore(&cpu5wdt_lock, flags);
  	if (verbose)

  		printk(KERN_CRIT PFX "stop not possible
  ");

  	return -EIO;
  }
  
  /* filesystem operations */
  
  static int cpu5wdt_open(struct inode *inode, struct file *file)
  {

  	if (test_and_set_bit(0, &cpu5wdt_device.inuse))

  		return -EBUSY;

  	return nonseekable_open(inode, file);
  }
  
  static int cpu5wdt_release(struct inode *inode, struct file *file)
  {
  	clear_bit(0, &cpu5wdt_device.inuse);
  	return 0;
  }

  static long cpu5wdt_ioctl(struct file *file, unsigned int cmd,
  						unsigned long arg)

  {
  	void __user *argp = (void __user *)arg;

  	int __user *p = argp;

  	unsigned int value;

  	static const struct watchdog_info ident = {

  		.options = WDIOF_CARDRESET,
  		.identity = "CPU5 WDT",
  	};

  	switch (cmd) {

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

  		break;
  	case WDIOC_GETSTATUS:
  		value = inb(port + CPU5WDT_STATUS_REG);
  		value = (value >> 2) & 1;
  		return put_user(value, p);
  	case WDIOC_GETBOOTSTATUS:
  		return put_user(0, p);

  	case WDIOC_SETOPTIONS:
  		if (get_user(value, p))
  			return -EFAULT;
  		if (value & WDIOS_ENABLECARD)
  			cpu5wdt_start();
  		if (value & WDIOS_DISABLECARD)
  			cpu5wdt_stop();
  		break;

  	case WDIOC_KEEPALIVE:
  		cpu5wdt_reset();
  		break;

  	default:
  		return -ENOTTY;

  	}
  	return 0;
  }

  static ssize_t cpu5wdt_write(struct file *file, const char __user *buf,
  						size_t count, loff_t *ppos)

  {

  	if (!count)

  		return -EIO;

  	cpu5wdt_reset();

  	return count;
  }

  static const struct file_operations cpu5wdt_fops = {

  	.owner		= THIS_MODULE,
  	.llseek		= no_llseek,

  	.unlocked_ioctl	= cpu5wdt_ioctl,

  	.open		= cpu5wdt_open,
  	.write		= cpu5wdt_write,
  	.release	= cpu5wdt_release,
  };
  
  static struct miscdevice cpu5wdt_misc = {
  	.minor	= WATCHDOG_MINOR,
  	.name	= "watchdog",
  	.fops	= &cpu5wdt_fops,
  };
  
  /* init/exit function */
  
  static int __devinit cpu5wdt_init(void)
  {
  	unsigned int val;
  	int err;

  	if (verbose)
  		printk(KERN_DEBUG PFX
  				"port=0x%x, verbose=%i
  ", port, verbose);

  	init_completion(&cpu5wdt_device.stop);

  	cpu5wdt_device.queue = 0;
  	setup_timer(&cpu5wdt_device.timer, cpu5wdt_trigger, 0);
  	cpu5wdt_device.default_ticks = ticks;
  
  	if (!request_region(port, CPU5WDT_EXTENT, PFX)) {

  		printk(KERN_ERR PFX "request_region failed
  ");
  		err = -EBUSY;
  		goto no_port;
  	}
  
  	/* watchdog reboot? */
  	val = inb(port + CPU5WDT_STATUS_REG);
  	val = (val >> 2) & 1;

  	if (!val)

  		printk(KERN_INFO PFX "sorry, was my fault
  ");

  	err = misc_register(&cpu5wdt_misc);
  	if (err < 0) {
  		printk(KERN_ERR PFX "misc_register failed
  ");
  		goto no_misc;
  	}

  
  	printk(KERN_INFO PFX "init success
  ");

  	return 0;

  no_misc:

  	release_region(port, CPU5WDT_EXTENT);
  no_port:

  	return err;
  }
  
  static int __devinit cpu5wdt_init_module(void)
  {
  	return cpu5wdt_init();
  }
  
  static void __devexit cpu5wdt_exit(void)
  {

  	if (cpu5wdt_device.queue) {

  		cpu5wdt_device.queue = 0;

  		wait_for_completion(&cpu5wdt_device.stop);

  	}
  
  	misc_deregister(&cpu5wdt_misc);
  
  	release_region(port, CPU5WDT_EXTENT);
  
  }
  
  static void __devexit cpu5wdt_exit_module(void)
  {
  	cpu5wdt_exit();
  }
  
  /* module entry points */
  
  module_init(cpu5wdt_init_module);
  module_exit(cpu5wdt_exit_module);
  
  MODULE_AUTHOR("Heiko Ronsdorf <hero@ihg.uni-duisburg.de>");
  MODULE_DESCRIPTION("sma cpu5 watchdog driver");
  MODULE_SUPPORTED_DEVICE("sma cpu5 watchdog");
  MODULE_LICENSE("GPL");
  MODULE_ALIAS_MISCDEV(WATCHDOG_MINOR);
  
  module_param(port, int, 0);
  MODULE_PARM_DESC(port, "base address of watchdog card, default is 0x91");
  
  module_param(verbose, int, 0);
  MODULE_PARM_DESC(verbose, "be verbose, default is 0 (no)");
  
  module_param(ticks, int, 0);
  MODULE_PARM_DESC(ticks, "count down ticks, default is 10000");