/*
   *	ALi M7101 PMU Computer Watchdog Timer driver
   *
   *	Based on w83877f_wdt.c by Scott Jennings <linuxdrivers@oro.net>
   *	and the Cobalt kernel WDT timer driver by Tim Hockin
   *	                                      <thockin@cobaltnet.com>
   *
   *	(c)2002 Steve Hill <steve@navaho.co.uk>
   *
   *  This WDT driver is different from most other Linux WDT
   *  drivers in that the driver will ping the watchdog by itself,
   *  because this particular WDT has a very short timeout (1.6
   *  seconds) and it would be insane to count on any userspace
   *  daemon always getting scheduled within that time frame.
   *
   *  Additions:
   *   Aug 23, 2004 - Added use_gpio module parameter for use on revision a1d PMUs
   *                  found on very old cobalt hardware.
   *                  -- Mike Waychison <michael.waychison@sun.com>
   */
  
  #include <linux/module.h>
  #include <linux/moduleparam.h>
  #include <linux/types.h>
  #include <linux/timer.h>
  #include <linux/miscdevice.h>
  #include <linux/watchdog.h>
  #include <linux/ioport.h>
  #include <linux/notifier.h>
  #include <linux/reboot.h>
  #include <linux/init.h>
  #include <linux/fs.h>
  #include <linux/pci.h>

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

  #include <asm/system.h>
  
  #define OUR_NAME "alim7101_wdt"
  #define PFX OUR_NAME ": "
  
  #define WDT_ENABLE 0x9C
  #define WDT_DISABLE 0x8C
  
  #define ALI_7101_WDT    0x92
  #define ALI_7101_GPIO   0x7D
  #define ALI_7101_GPIO_O 0x7E
  #define ALI_WDT_ARM     0x01
  
  /*
   * We're going to use a 1 second timeout.
   * If we reset the watchdog every ~250ms we should be safe.  */
  
  #define WDT_INTERVAL (HZ/4+1)
  
  /*
   * We must not require too good response from the userspace daemon.
   * Here we require the userspace daemon to send us a heartbeat
   * char to /dev/watchdog every 30 seconds.
   */
  
  #define WATCHDOG_TIMEOUT 30            /* 30 sec default timeout */

  /* in seconds, will be multiplied by HZ to get seconds to wait for a ping */
  static int timeout = WATCHDOG_TIMEOUT;

  module_param(timeout, int, 0);

  MODULE_PARM_DESC(timeout,
  		"Watchdog timeout in seconds. (1<=timeout<=3600, default="
  				__MODULE_STRING(WATCHDOG_TIMEOUT) ")");

  static int use_gpio; /* Use the pic (for a1d revision alim7101) */

  module_param(use_gpio, int, 0);

  MODULE_PARM_DESC(use_gpio,
  		"Use the gpio watchdog (required by old cobalt boards).");

  
  static void wdt_timer_ping(unsigned long);

  static DEFINE_TIMER(timer, wdt_timer_ping, 0, 1);

  static unsigned long next_heartbeat;
  static unsigned long wdt_is_open;
  static char wdt_expect_close;
  static struct pci_dev *alim7101_pmu;

  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) ")");

  
  /*
   *	Whack the dog
   */
  
  static void wdt_timer_ping(unsigned long data)
  {
  	/* If we got a heartbeat pulse within the WDT_US_INTERVAL
  	 * we agree to ping the WDT
  	 */

  	char tmp;

  	if (time_before(jiffies, next_heartbeat)) {

  		/* Ping the WDT (this is actually a disarm/arm sequence) */
  		pci_read_config_byte(alim7101_pmu, 0x92, &tmp);

  		pci_write_config_byte(alim7101_pmu,
  					ALI_7101_WDT, (tmp & ~ALI_WDT_ARM));
  		pci_write_config_byte(alim7101_pmu,
  					ALI_7101_WDT, (tmp | ALI_WDT_ARM));

  		if (use_gpio) {

  			pci_read_config_byte(alim7101_pmu,
  					ALI_7101_GPIO_O, &tmp);
  			pci_write_config_byte(alim7101_pmu,
  					ALI_7101_GPIO_O, tmp | 0x20);
  			pci_write_config_byte(alim7101_pmu,
  					ALI_7101_GPIO_O, tmp & ~0x20);

  		}
  	} else {

  		printk(KERN_WARNING PFX
  			"Heartbeat lost! Will not ping the watchdog
  ");

  	}
  	/* Re-set the timer interval */

  	mod_timer(&timer, jiffies + WDT_INTERVAL);

  }
  
  /*
   * Utility routines
   */
  
  static void wdt_change(int writeval)
  {

  	char tmp;

  
  	pci_read_config_byte(alim7101_pmu, ALI_7101_WDT, &tmp);
  	if (writeval == WDT_ENABLE) {

  		pci_write_config_byte(alim7101_pmu,
  					ALI_7101_WDT, (tmp | ALI_WDT_ARM));

  		if (use_gpio) {

  			pci_read_config_byte(alim7101_pmu,
  					ALI_7101_GPIO_O, &tmp);
  			pci_write_config_byte(alim7101_pmu,
  					ALI_7101_GPIO_O, tmp & ~0x20);

  		}
  
  	} else {

  		pci_write_config_byte(alim7101_pmu,
  					ALI_7101_WDT, (tmp & ~ALI_WDT_ARM));

  		if (use_gpio) {

  			pci_read_config_byte(alim7101_pmu,
  					ALI_7101_GPIO_O, &tmp);
  			pci_write_config_byte(alim7101_pmu,
  					ALI_7101_GPIO_O, tmp | 0x20);

  		}
  	}
  }
  
  static void wdt_startup(void)
  {
  	next_heartbeat = jiffies + (timeout * HZ);
  
  	/* We must enable before we kick off the timer in case the timer
  	   occurs as we ping it */
  
  	wdt_change(WDT_ENABLE);
  
  	/* Start the timer */

  	mod_timer(&timer, jiffies + WDT_INTERVAL);

  
  	printk(KERN_INFO PFX "Watchdog timer is now enabled.
  ");
  }
  
  static void wdt_turnoff(void)
  {
  	/* Stop the timer */
  	del_timer_sync(&timer);
  	wdt_change(WDT_DISABLE);
  	printk(KERN_INFO PFX "Watchdog timer is now disabled...
  ");
  }
  
  static void wdt_keepalive(void)
  {
  	/* user land ping */
  	next_heartbeat = jiffies + (timeout * HZ);
  }
  
  /*
   * /dev/watchdog handling
   */

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

  {
  	/* See if we got the magic character 'V' and reload the timer */

  	if (count) {

  		if (!nowayout) {
  			size_t ofs;
  
  			/* note: just in case someone wrote the magic character
  			 * five months ago... */
  			wdt_expect_close = 0;
  
  			/* now scan */
  			for (ofs = 0; ofs != count; ofs++) {
  				char c;

  				if (get_user(c, buf + ofs))

  					return -EFAULT;
  				if (c == 'V')
  					wdt_expect_close = 42;
  			}
  		}
  		/* someone wrote to us, we should restart timer */
  		wdt_keepalive();
  	}
  	return count;
  }

  static int fop_open(struct inode *inode, struct file *file)

  {
  	/* Just in case we're already talking to someone... */

  	if (test_and_set_bit(0, &wdt_is_open))

  		return -EBUSY;
  	/* Good, fire up the show */
  	wdt_startup();
  	return nonseekable_open(inode, file);
  }

  static int fop_close(struct inode *inode, struct file *file)

  {

  	if (wdt_expect_close == 42)

  		wdt_turnoff();
  	else {
  		/* wim: shouldn't there be a: del_timer(&timer); */

  		printk(KERN_CRIT PFX
  		  "device file closed unexpectedly. Will not stop the WDT!
  ");

  	}
  	clear_bit(0, &wdt_is_open);
  	wdt_expect_close = 0;
  	return 0;
  }

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

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

  	static const struct watchdog_info ident = {

  		.options = WDIOF_KEEPALIVEPING | WDIOF_SETTIMEOUT
  							| WDIOF_MAGICCLOSE,

  		.firmware_version = 1,
  		.identity = "ALiM7101",
  	};

  	switch (cmd) {
  	case WDIOC_GETSUPPORT:
  		return copy_to_user(argp, &ident, sizeof(ident)) ? -EFAULT : 0;
  	case WDIOC_GETSTATUS:
  	case WDIOC_GETBOOTSTATUS:
  		return put_user(0, p);

  	case WDIOC_SETOPTIONS:

  	{

  		int new_options, retval = -EINVAL;

  		if (get_user(new_options, p))
  			return -EFAULT;
  		if (new_options & WDIOS_DISABLECARD) {
  			wdt_turnoff();
  			retval = 0;

  		}

  		if (new_options & WDIOS_ENABLECARD) {
  			wdt_startup();
  			retval = 0;

  		}

  		return retval;
  	}

  	case WDIOC_KEEPALIVE:
  		wdt_keepalive();
  		return 0;

  	case WDIOC_SETTIMEOUT:
  	{
  		int new_timeout;
  
  		if (get_user(new_timeout, p))
  			return -EFAULT;
  		/* arbitrary upper limit */
  		if (new_timeout < 1 || new_timeout > 3600)
  			return -EINVAL;
  		timeout = new_timeout;
  		wdt_keepalive();
  		/* Fall through */
  	}
  	case WDIOC_GETTIMEOUT:
  		return put_user(timeout, p);
  	default:
  		return -ENOTTY;

  	}
  }

  static const struct file_operations wdt_fops = {

  	.owner		=	THIS_MODULE,
  	.llseek		=	no_llseek,
  	.write		=	fop_write,
  	.open		=	fop_open,
  	.release	=	fop_close,
  	.unlocked_ioctl	=	fop_ioctl,

  };
  
  static struct miscdevice wdt_miscdev = {

  	.minor	=	WATCHDOG_MINOR,
  	.name	=	"watchdog",
  	.fops	=	&wdt_fops,

  };
  
  /*
   *	Notifier for system down
   */

  static int wdt_notify_sys(struct notifier_block *this,
  					unsigned long code, void *unused)

  {

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

  		wdt_turnoff();

  	if (code == SYS_RESTART) {

  		/*

  		 * Cobalt devices have no way of rebooting themselves other
  		 * than getting the watchdog to pull reset, so we restart the
  		 * watchdog on reboot with no heartbeat

  		 */
  		wdt_change(WDT_ENABLE);

  		printk(KERN_INFO PFX "Watchdog timer is now enabled "
  			"with no heartbeat - should reboot in ~1 second.
  ");

  	}
  	return NOTIFY_DONE;
  }
  
  /*
   *	The WDT needs to learn about soft shutdowns in order to
   *	turn the timebomb registers off.
   */

  static struct notifier_block wdt_notifier = {

  	.notifier_call = wdt_notify_sys,
  };
  
  static void __exit alim7101_wdt_unload(void)
  {
  	wdt_turnoff();
  	/* Deregister */
  	misc_deregister(&wdt_miscdev);
  	unregister_reboot_notifier(&wdt_notifier);

  	pci_dev_put(alim7101_pmu);

  }
  
  static int __init alim7101_wdt_init(void)
  {
  	int rc = -EBUSY;
  	struct pci_dev *ali1543_south;
  	char tmp;
  
  	printk(KERN_INFO PFX "Steve Hill <steve@navaho.co.uk>.
  ");

  	alim7101_pmu = pci_get_device(PCI_VENDOR_ID_AL, PCI_DEVICE_ID_AL_M7101,
  		NULL);

  	if (!alim7101_pmu) {

  		printk(KERN_INFO PFX
  			"ALi M7101 PMU not present - WDT not set
  ");

  		return -EBUSY;
  	}
  
  	/* Set the WDT in the PMU to 1 second */
  	pci_write_config_byte(alim7101_pmu, ALI_7101_WDT, 0x02);

  	ali1543_south = pci_get_device(PCI_VENDOR_ID_AL, PCI_DEVICE_ID_AL_M1533,
  		NULL);

  	if (!ali1543_south) {

  		printk(KERN_INFO PFX
  			"ALi 1543 South-Bridge not present - WDT not set
  ");

  		goto err_out;

  	}
  	pci_read_config_byte(ali1543_south, 0x5e, &tmp);

  	pci_dev_put(ali1543_south);

  	if ((tmp & 0x1e) == 0x00) {
  		if (!use_gpio) {

  			printk(KERN_INFO PFX
  				"Detected old alim7101 revision 'a1d'.  "
  				"If this is a cobalt board, set the 'use_gpio' "
  				"module parameter.
  ");

  			goto err_out;

  		}

  		nowayout = 1;
  	} else if ((tmp & 0x1e) != 0x12 && (tmp & 0x1e) != 0x00) {

  		printk(KERN_INFO PFX
  			"ALi 1543 South-Bridge does not have the correct "
  			"revision number (???1001?) - WDT not set
  ");

  		goto err_out;

  	}

  	if (timeout < 1 || timeout > 3600) {
  		/* arbitrary upper limit */

  		timeout = WATCHDOG_TIMEOUT;

  		printk(KERN_INFO PFX
  			"timeout value must be 1 <= x <= 3600, using %d
  ",
  								timeout);

  	}

  	rc = register_reboot_notifier(&wdt_notifier);

  	if (rc) {

  		printk(KERN_ERR PFX
  			"cannot register reboot notifier (err=%d)
  ", rc);

  		goto err_out;
  	}

  	rc = misc_register(&wdt_miscdev);

  	if (rc) {

  		printk(KERN_ERR PFX
  			"cannot register miscdev on minor=%d (err=%d)
  ",

  			wdt_miscdev.minor, rc);
  		goto err_out_reboot;

  	}

  	if (nowayout)

  		__module_get(THIS_MODULE);

  	printk(KERN_INFO PFX "WDT driver for ALi M7101 initialised. "
  					"timeout=%d sec (nowayout=%d)
  ",

  		timeout, nowayout);
  	return 0;

  err_out_reboot:
  	unregister_reboot_notifier(&wdt_notifier);

  err_out:

  	pci_dev_put(alim7101_pmu);

  	return rc;
  }
  
  module_init(alim7101_wdt_init);
  module_exit(alim7101_wdt_unload);

  static DEFINE_PCI_DEVICE_TABLE(alim7101_pci_tbl) __used = {

  	{ PCI_DEVICE(PCI_VENDOR_ID_AL, PCI_DEVICE_ID_AL_M1533) },
  	{ PCI_DEVICE(PCI_VENDOR_ID_AL, PCI_DEVICE_ID_AL_M7101) },

  	{ }
  };
  
  MODULE_DEVICE_TABLE(pci, alim7101_pci_tbl);

  MODULE_AUTHOR("Steve Hill");
  MODULE_DESCRIPTION("ALi M7101 PMU Computer Watchdog Timer driver");
  MODULE_LICENSE("GPL");
  MODULE_ALIAS_MISCDEV(WATCHDOG_MINOR);