/*
   *	Watchdog driver for the mpcore watchdog timer
   *
   *	(c) Copyright 2004 ARM Limited
   *
   *	Based on the SoftDog driver:

   *	(c) Copyright 1996 Alan Cox <alan@lxorguk.ukuu.org.uk>,

   *						All Rights Reserved.

   *
   *	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>
   *
   */
  #include <linux/module.h>
  #include <linux/moduleparam.h>

  #include <linux/types.h>
  #include <linux/miscdevice.h>
  #include <linux/watchdog.h>
  #include <linux/fs.h>
  #include <linux/reboot.h>
  #include <linux/init.h>
  #include <linux/interrupt.h>

  #include <linux/platform_device.h>

  #include <linux/uaccess.h>

  #include <linux/slab.h>

  #include <linux/io.h>

  #include <asm/smp_twd.h>

  
  struct mpcore_wdt {
  	unsigned long	timer_alive;
  	struct device	*dev;
  	void __iomem	*base;
  	int		irq;
  	unsigned int	perturb;
  	char		expect_close;
  };
  
  static struct platform_device *mpcore_wdt_dev;

  static DEFINE_SPINLOCK(wdt_lock);

  
  #define TIMER_MARGIN	60
  static int mpcore_margin = TIMER_MARGIN;
  module_param(mpcore_margin, int, 0);

  MODULE_PARM_DESC(mpcore_margin,
  	"MPcore timer margin in seconds. (0 < mpcore_margin < 65536, default="
  				__MODULE_STRING(TIMER_MARGIN) ")");

  
  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) ")");

  
  #define ONLY_TESTING	0
  static int mpcore_noboot = ONLY_TESTING;
  module_param(mpcore_noboot, int, 0);

  MODULE_PARM_DESC(mpcore_noboot, "MPcore watchdog action, "
  	"set to 1 to ignore reboots, 0 to reboot (default="
  					__MODULE_STRING(ONLY_TESTING) ")");

  
  /*
   *	This is the interrupt handler.  Note that we only use this
   *	in testing mode, so don't actually do a reboot here.
   */

  static irqreturn_t mpcore_wdt_fire(int irq, void *arg)

  {
  	struct mpcore_wdt *wdt = arg;
  
  	/* Check it really was our interrupt */
  	if (readl(wdt->base + TWD_WDOG_INTSTAT)) {

  		dev_printk(KERN_CRIT, wdt->dev,
  					"Triggered - Reboot ignored.
  ");

  		/* Clear the interrupt on the watchdog */
  		writel(1, wdt->base + TWD_WDOG_INTSTAT);

  		return IRQ_HANDLED;
  	}

  	return IRQ_NONE;
  }
  
  /*
   *	mpcore_wdt_keepalive - reload the timer
   *
   *	Note that the spec says a DIFFERENT value must be written to the reload
   *	register each time.  The "perturb" variable deals with this by adding 1
   *	to the count every other time the function is called.
   */
  static void mpcore_wdt_keepalive(struct mpcore_wdt *wdt)
  {

  	unsigned long count;

  	spin_lock(&wdt_lock);

  	/* Assume prescale is set to 256 */

  	count =  __raw_readl(wdt->base + TWD_WDOG_COUNTER);
  	count = (0xFFFFFFFFU - count) * (HZ / 5);
  	count = (count / 256) * mpcore_margin;

  
  	/* Reload the counter */
  	writel(count + wdt->perturb, wdt->base + TWD_WDOG_LOAD);

  	wdt->perturb = wdt->perturb ? 0 : 1;

  	spin_unlock(&wdt_lock);

  }
  
  static void mpcore_wdt_stop(struct mpcore_wdt *wdt)
  {

  	spin_lock(&wdt_lock);

  	writel(0x12345678, wdt->base + TWD_WDOG_DISABLE);
  	writel(0x87654321, wdt->base + TWD_WDOG_DISABLE);
  	writel(0x0, wdt->base + TWD_WDOG_CONTROL);

  	spin_unlock(&wdt_lock);

  }
  
  static void mpcore_wdt_start(struct mpcore_wdt *wdt)
  {
  	dev_printk(KERN_INFO, wdt->dev, "enabling watchdog.
  ");
  
  	/* This loads the count register but does NOT start the count yet */
  	mpcore_wdt_keepalive(wdt);
  
  	if (mpcore_noboot) {
  		/* Enable watchdog - prescale=256, watchdog mode=0, enable=1 */
  		writel(0x0000FF01, wdt->base + TWD_WDOG_CONTROL);
  	} else {
  		/* Enable watchdog - prescale=256, watchdog mode=1, enable=1 */
  		writel(0x0000FF09, wdt->base + TWD_WDOG_CONTROL);
  	}
  }
  
  static int mpcore_wdt_set_heartbeat(int t)
  {
  	if (t < 0x0001 || t > 0xFFFF)
  		return -EINVAL;
  
  	mpcore_margin = t;
  	return 0;
  }
  
  /*
   *	/dev/watchdog handling
   */
  static int mpcore_wdt_open(struct inode *inode, struct file *file)
  {

  	struct mpcore_wdt *wdt = platform_get_drvdata(mpcore_wdt_dev);

  
  	if (test_and_set_bit(0, &wdt->timer_alive))
  		return -EBUSY;
  
  	if (nowayout)
  		__module_get(THIS_MODULE);
  
  	file->private_data = wdt;
  
  	/*
  	 *	Activate timer
  	 */
  	mpcore_wdt_start(wdt);
  
  	return nonseekable_open(inode, file);
  }
  
  static int mpcore_wdt_release(struct inode *inode, struct file *file)
  {
  	struct mpcore_wdt *wdt = file->private_data;
  
  	/*
  	 *	Shut off the timer.

  	 *	Lock it in if it's a module and we set nowayout

  	 */

  	if (wdt->expect_close == 42)

  		mpcore_wdt_stop(wdt);

  	else {
  		dev_printk(KERN_CRIT, wdt->dev,
  				"unexpected close, not stopping watchdog!
  ");

  		mpcore_wdt_keepalive(wdt);
  	}
  	clear_bit(0, &wdt->timer_alive);
  	wdt->expect_close = 0;
  	return 0;
  }

  static ssize_t mpcore_wdt_write(struct file *file, const char *data,
  						size_t len, loff_t *ppos)

  {
  	struct mpcore_wdt *wdt = file->private_data;

  	/*
  	 *	Refresh the timer.
  	 */
  	if (len) {
  		if (!nowayout) {
  			size_t i;
  
  			/* In case it was set long ago */
  			wdt->expect_close = 0;
  
  			for (i = 0; i != len; i++) {
  				char c;
  
  				if (get_user(c, data + i))
  					return -EFAULT;
  				if (c == 'V')
  					wdt->expect_close = 42;
  			}
  		}
  		mpcore_wdt_keepalive(wdt);
  	}
  	return len;
  }

  static const struct watchdog_info ident = {

  	.options		= WDIOF_SETTIMEOUT |
  				  WDIOF_KEEPALIVEPING |
  				  WDIOF_MAGICCLOSE,
  	.identity		= "MPcore Watchdog",
  };

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

  {
  	struct mpcore_wdt *wdt = file->private_data;
  	int ret;
  	union {
  		struct watchdog_info ident;
  		int i;
  	} uarg;
  
  	if (_IOC_DIR(cmd) && _IOC_SIZE(cmd) > sizeof(uarg))

  		return -ENOTTY;

  
  	if (_IOC_DIR(cmd) & _IOC_WRITE) {
  		ret = copy_from_user(&uarg, (void __user *)arg, _IOC_SIZE(cmd));
  		if (ret)
  			return -EFAULT;
  	}
  
  	switch (cmd) {
  	case WDIOC_GETSUPPORT:
  		uarg.ident = ident;
  		ret = 0;
  		break;

  	case WDIOC_GETSTATUS:
  	case WDIOC_GETBOOTSTATUS:
  		uarg.i = 0;
  		ret = 0;
  		break;

  	case WDIOC_SETOPTIONS:
  		ret = -EINVAL;
  		if (uarg.i & WDIOS_DISABLECARD) {
  			mpcore_wdt_stop(wdt);
  			ret = 0;
  		}
  		if (uarg.i & WDIOS_ENABLECARD) {
  			mpcore_wdt_start(wdt);
  			ret = 0;
  		}
  		break;

  	case WDIOC_KEEPALIVE:
  		mpcore_wdt_keepalive(wdt);
  		ret = 0;
  		break;
  
  	case WDIOC_SETTIMEOUT:
  		ret = mpcore_wdt_set_heartbeat(uarg.i);
  		if (ret)
  			break;
  
  		mpcore_wdt_keepalive(wdt);
  		/* Fall */
  	case WDIOC_GETTIMEOUT:
  		uarg.i = mpcore_margin;
  		ret = 0;
  		break;
  
  	default:

  		return -ENOTTY;

  	}
  
  	if (ret == 0 && _IOC_DIR(cmd) & _IOC_READ) {
  		ret = copy_to_user((void __user *)arg, &uarg, _IOC_SIZE(cmd));
  		if (ret)
  			ret = -EFAULT;
  	}
  	return ret;
  }
  
  /*
   *	System shutdown handler.  Turn off the watchdog if we're
   *	restarting or halting the system.
   */

  static void mpcore_wdt_shutdown(struct platform_device *dev)

  {

  	struct mpcore_wdt *wdt = platform_get_drvdata(dev);

  
  	if (system_state == SYSTEM_RESTART || system_state == SYSTEM_HALT)
  		mpcore_wdt_stop(wdt);
  }
  
  /*
   *	Kernel Interfaces
   */

  static const struct file_operations mpcore_wdt_fops = {

  	.owner		= THIS_MODULE,
  	.llseek		= no_llseek,
  	.write		= mpcore_wdt_write,

  	.unlocked_ioctl	= mpcore_wdt_ioctl,

  	.open		= mpcore_wdt_open,
  	.release	= mpcore_wdt_release,
  };
  
  static struct miscdevice mpcore_wdt_miscdev = {
  	.minor		= WATCHDOG_MINOR,
  	.name		= "watchdog",
  	.fops		= &mpcore_wdt_fops,
  };

  static int __devinit mpcore_wdt_probe(struct platform_device *dev)

  {

  	struct mpcore_wdt *wdt;
  	struct resource *res;
  	int ret;
  
  	/* We only accept one device, and it must have an id of -1 */
  	if (dev->id != -1)
  		return -ENODEV;
  
  	res = platform_get_resource(dev, IORESOURCE_MEM, 0);
  	if (!res) {
  		ret = -ENODEV;
  		goto err_out;
  	}

  	wdt = kzalloc(sizeof(struct mpcore_wdt), GFP_KERNEL);

  	if (!wdt) {
  		ret = -ENOMEM;
  		goto err_out;
  	}

  
  	wdt->dev = &dev->dev;
  	wdt->irq = platform_get_irq(dev, 0);

  	if (wdt->irq < 0) {
  		ret = -ENXIO;
  		goto err_free;
  	}

  	wdt->base = ioremap(res->start, resource_size(res));

  	if (!wdt->base) {
  		ret = -ENOMEM;
  		goto err_free;
  	}

  	mpcore_wdt_miscdev.parent = &dev->dev;

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

  		dev_printk(KERN_ERR, wdt->dev,

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

  		goto err_misc;
  	}

  	ret = request_irq(wdt->irq, mpcore_wdt_fire, 0, "mpcore_wdt", wdt);

  	if (ret) {

  		dev_printk(KERN_ERR, wdt->dev,

  			"cannot register IRQ%d for watchdog
  ", wdt->irq);

  		goto err_irq;
  	}
  
  	mpcore_wdt_stop(wdt);

  	platform_set_drvdata(dev, wdt);

  	mpcore_wdt_dev = dev;
  
  	return 0;

  err_irq:

  	misc_deregister(&mpcore_wdt_miscdev);

  err_misc:

  	iounmap(wdt->base);

  err_free:

  	kfree(wdt);

  err_out:

  	return ret;
  }

  static int __devexit mpcore_wdt_remove(struct platform_device *dev)

  {

  	struct mpcore_wdt *wdt = platform_get_drvdata(dev);

  	platform_set_drvdata(dev, NULL);

  
  	misc_deregister(&mpcore_wdt_miscdev);
  
  	mpcore_wdt_dev = NULL;
  
  	free_irq(wdt->irq, wdt);
  	iounmap(wdt->base);
  	kfree(wdt);
  	return 0;
  }

  #ifdef CONFIG_PM
  static int mpcore_wdt_suspend(struct platform_device *dev, pm_message_t msg)
  {
  	struct mpcore_wdt *wdt = platform_get_drvdata(dev);
  	mpcore_wdt_stop(wdt);		/* Turn the WDT off */
  	return 0;
  }
  
  static int mpcore_wdt_resume(struct platform_device *dev)
  {
  	struct mpcore_wdt *wdt = platform_get_drvdata(dev);
  	/* re-activate timer */
  	if (test_bit(0, &wdt->timer_alive))
  		mpcore_wdt_start(wdt);
  	return 0;
  }
  #else
  #define mpcore_wdt_suspend	NULL
  #define mpcore_wdt_resume	NULL
  #endif

  /* work with hotplug and coldplug */
  MODULE_ALIAS("platform:mpcore_wdt");

  static struct platform_driver mpcore_wdt_driver = {

  	.probe		= mpcore_wdt_probe,
  	.remove		= __devexit_p(mpcore_wdt_remove),

  	.suspend	= mpcore_wdt_suspend,
  	.resume		= mpcore_wdt_resume,

  	.shutdown	= mpcore_wdt_shutdown,

  	.driver		= {
  		.owner	= THIS_MODULE,
  		.name	= "mpcore_wdt",
  	},

  };

  static char banner[] __initdata = KERN_INFO "MPcore Watchdog Timer: 0.1. "
  		"mpcore_noboot=%d mpcore_margin=%d sec (nowayout= %d)
  ";

  
  static int __init mpcore_wdt_init(void)
  {
  	/*
  	 * Check that the margin value is within it's range;
  	 * if not reset to the default
  	 */
  	if (mpcore_wdt_set_heartbeat(mpcore_margin)) {
  		mpcore_wdt_set_heartbeat(TIMER_MARGIN);

  		printk(KERN_INFO "mpcore_margin value must be 0 < mpcore_margin < 65536, using %d
  ",

  			TIMER_MARGIN);
  	}
  
  	printk(banner, mpcore_noboot, mpcore_margin, nowayout);

  	return platform_driver_register(&mpcore_wdt_driver);

  }
  
  static void __exit mpcore_wdt_exit(void)
  {

  	platform_driver_unregister(&mpcore_wdt_driver);

  }
  
  module_init(mpcore_wdt_init);
  module_exit(mpcore_wdt_exit);
  
  MODULE_AUTHOR("ARM Limited");
  MODULE_DESCRIPTION("MPcore Watchdog Device Driver");
  MODULE_LICENSE("GPL");
  MODULE_ALIAS_MISCDEV(WATCHDOG_MINOR);