text: /* $Id: riowatchdog.c,v 1.3.2.2 2002/01/23 18:48:02 davem Exp $
   * riowatchdog.c - driver for hw watchdog inside Super I/O of RIO
   *
   * Copyright (C) 2001 David S. Miller (davem@redhat.com)
   */
  
  #include <linux/kernel.h>
  #include <linux/module.h>
  #include <linux/types.h>
  #include <linux/fs.h>
  #include <linux/errno.h>
  #include <linux/init.h>
  #include <linux/miscdevice.h>
  
  #include <asm/io.h>
  #include <asm/ebus.h>
  #include <asm/bbc.h>
  #include <asm/oplib.h>
  #include <asm/uaccess.h>
  
  #include <asm/watchdog.h>
  
  /* RIO uses the NatSemi Super I/O power management logical device
   * as its' watchdog.
   *
   * When the watchdog triggers, it asserts a line to the BBC (Boot Bus
   * Controller) of the machine.  The BBC can only be configured to
   * trigger a power-on reset when the signal is asserted.  The BBC
   * can be configured to ignore the signal entirely as well.
   *
   * The only Super I/O device register we care about is at index
   * 0x05 (WDTO_INDEX) which is the watchdog time-out in minutes (1-255).
   * If set to zero, this disables the watchdog.  When set, the system
   * must periodically (before watchdog expires) clear (set to zero) and
   * re-set the watchdog else it will trigger.
   *
   * There are two other indexed watchdog registers inside this Super I/O
   * logical device, but they are unused.  The first, at index 0x06 is
   * the watchdog control and can be used to make the watchdog timer re-set
   * when the PS/2 mouse or serial lines show activity.  The second, at
   * index 0x07 is merely a sampling of the line from the watchdog to the
   * BBC.
   *
   * The watchdog device generates no interrupts.
   */
  
  MODULE_AUTHOR("David S. Miller <davem@redhat.com>");
  MODULE_DESCRIPTION("Hardware watchdog driver for Sun RIO");
  MODULE_SUPPORTED_DEVICE("watchdog");
  MODULE_LICENSE("GPL");
  
  #define RIOWD_NAME	"pmc"
  #define RIOWD_MINOR	215
  
  static DEFINE_SPINLOCK(riowd_lock);
  
  static void __iomem *bbc_regs;
  static void __iomem *riowd_regs;
  #define WDTO_INDEX	0x05
  
  static int riowd_timeout = 1;		/* in minutes */
  module_param(riowd_timeout, int, 0);
  MODULE_PARM_DESC(riowd_timeout, "Watchdog timeout in minutes");
  
  #if 0 /* Currently unused. */
  static u8 riowd_readreg(int index)
  {
  	unsigned long flags;
  	u8 ret;
  
  	spin_lock_irqsave(&riowd_lock, flags);
  	writeb(index, riowd_regs + 0);
  	ret = readb(riowd_regs + 1);
  	spin_unlock_irqrestore(&riowd_lock, flags);
  
  	return ret;
  }
  #endif
  
  static void riowd_writereg(u8 val, int index)
  {
  	unsigned long flags;
  
  	spin_lock_irqsave(&riowd_lock, flags);
  	writeb(index, riowd_regs + 0);
  	writeb(val, riowd_regs + 1);
  	spin_unlock_irqrestore(&riowd_lock, flags);
  }
  
  static void riowd_pingtimer(void)
  {
  	riowd_writereg(riowd_timeout, WDTO_INDEX);
  }
  
  static void riowd_stoptimer(void)
  {
  	u8 val;
  
  	riowd_writereg(0, WDTO_INDEX);
  
  	val = readb(bbc_regs + BBC_WDACTION);
  	val &= ~BBC_WDACTION_RST;
  	writeb(val, bbc_regs + BBC_WDACTION);
  }
  
  static void riowd_starttimer(void)
  {
  	u8 val;
  
  	riowd_writereg(riowd_timeout, WDTO_INDEX);
  
  	val = readb(bbc_regs + BBC_WDACTION);
  	val |= BBC_WDACTION_RST;
  	writeb(val, bbc_regs + BBC_WDACTION);
  }
  
  static int riowd_open(struct inode *inode, struct file *filp)
  {
  	nonseekable_open(inode, filp);
  	return 0;
  }
  
  static int riowd_release(struct inode *inode, struct file *filp)
  {
  	return 0;
  }
  
  static int riowd_ioctl(struct inode *inode, struct file *filp,
  		       unsigned int cmd, unsigned long arg)
  {
  	static struct watchdog_info info = {
  	       	WDIOF_SETTIMEOUT, 0, "Natl. Semiconductor PC97317"
  	};
  	void __user *argp = (void __user *)arg;
  	unsigned int options;
  	int new_margin;
  
  	switch (cmd) {
  	case WDIOC_GETSUPPORT:
  		if (copy_to_user(argp, &info, sizeof(info)))
  			return -EFAULT;
  		break;
  
  	case WDIOC_GETSTATUS:
  	case WDIOC_GETBOOTSTATUS:
  		if (put_user(0, (int __user *)argp))
  			return -EFAULT;
  		break;
  
  	case WDIOC_KEEPALIVE:
  		riowd_pingtimer();
  		break;
  
  	case WDIOC_SETOPTIONS:
  		if (copy_from_user(&options, argp, sizeof(options)))
  			return -EFAULT;
  
  		if (options & WDIOS_DISABLECARD)
  			riowd_stoptimer();
  		else if (options & WDIOS_ENABLECARD)
  			riowd_starttimer();
  		else
  			return -EINVAL;
  
  		break;
  
  	case WDIOC_SETTIMEOUT:
  		if (get_user(new_margin, (int __user *)argp))
  			return -EFAULT;
  		if ((new_margin < 60) || (new_margin > (255 * 60)))
  		    return -EINVAL;
  		riowd_timeout = (new_margin + 59) / 60;
  		riowd_pingtimer();
  		/* Fall */
  
  	case WDIOC_GETTIMEOUT:
  		return put_user(riowd_timeout * 60, (int __user *)argp);
  
  	default:
  		return -EINVAL;
  	};
  
  	return 0;
  }
  
  static ssize_t riowd_write(struct file *file, const char __user *buf, size_t count, loff_t *ppos)
  {
  	if (count) {
  		riowd_pingtimer();
  		return 1;
  	}
  
  	return 0;
  }
  
  static struct file_operations riowd_fops = {
  	.owner =	THIS_MODULE,
  	.ioctl =	riowd_ioctl,
  	.open =		riowd_open,
  	.write =	riowd_write,
  	.release =	riowd_release,
  };
  
  static struct miscdevice riowd_miscdev = { RIOWD_MINOR, RIOWD_NAME, &riowd_fops };
  
  static int __init riowd_bbc_init(void)
  {
  	struct 	linux_ebus *ebus = NULL;
  	struct 	linux_ebus_device *edev = NULL;
  	u8 val;
  
  	for_each_ebus(ebus) {
  		for_each_ebusdev(edev, ebus) {
  			if (!strcmp(edev->prom_name, "bbc"))
  				goto found_bbc;
  		}
  	}
  
  found_bbc:
  	if (!edev)
  		return -ENODEV;
  	bbc_regs = ioremap(edev->resource[0].start, BBC_REGS_SIZE);
  	if (!bbc_regs)
  		return -ENODEV;
  
  	/* Turn it off. */
  	val = readb(bbc_regs + BBC_WDACTION);
  	val &= ~BBC_WDACTION_RST;
  	writeb(val, bbc_regs + BBC_WDACTION);
  
  	return 0;
  }
  
  static int __init riowd_init(void)
  {
  	struct 	linux_ebus *ebus = NULL;
  	struct 	linux_ebus_device *edev = NULL;
  
  	for_each_ebus(ebus) {
  		for_each_ebusdev(edev, ebus) {
  			if (!strcmp(edev->prom_name, RIOWD_NAME))
  				goto ebus_done;
  		}
  	}
  
  ebus_done:
  	if (!edev)
  		goto fail;
  
  	riowd_regs = ioremap(edev->resource[0].start, 2);
  	if (riowd_regs == NULL) {
  		printk(KERN_ERR "pmc: Cannot map registers.\n");
  		return -ENODEV;
  	}
  
  	if (riowd_bbc_init()) {
  		printk(KERN_ERR "pmc: Failure initializing BBC config.\n");
  		goto fail;
  	}
  
  	if (misc_register(&riowd_miscdev)) {
  		printk(KERN_ERR "pmc: Cannot register watchdog misc device.\n");
  		goto fail;
  	}
  
  	printk(KERN_INFO "pmc: Hardware watchdog [%i minutes], "
  	       "regs at %p\n", riowd_timeout, riowd_regs);
  
  	return 0;
  
  fail:
  	if (riowd_regs) {
  		iounmap(riowd_regs);
  		riowd_regs = NULL;
  	}
  	if (bbc_regs) {
  		iounmap(bbc_regs);
  		bbc_regs = NULL;
  	}
  	return -ENODEV;
  }
  
  static void __exit riowd_cleanup(void)
  {
  	misc_deregister(&riowd_miscdev);
  	iounmap(riowd_regs);
  	riowd_regs = NULL;
  	iounmap(bbc_regs);
  	bbc_regs = NULL;
  }
  
  module_init(riowd_init);
  module_exit(riowd_cleanup);
  