/*
   *	Watchdog for the 7101 PMU version found in the ALi M1535 chipsets
   *
   *	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.
   */

  #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt

  #include <linux/module.h>
  #include <linux/moduleparam.h>
  #include <linux/types.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/uaccess.h>
  #include <linux/io.h>

  
  #define WATCHDOG_NAME "ALi_M1535"

  #define WATCHDOG_TIMEOUT 60	/* 60 sec default timeout */
  
  /* internal variables */
  static unsigned long ali_is_open;
  static char ali_expect_release;
  static struct pci_dev *ali_pci;

  static u32 ali_timeout_bits;		/* stores the computed timeout */

  static DEFINE_SPINLOCK(ali_lock);	/* Guards the hardware */

  
  /* module parameters */
  static int timeout = WATCHDOG_TIMEOUT;
  module_param(timeout, int, 0);

  MODULE_PARM_DESC(timeout,
  		"Watchdog timeout in seconds. (0 < timeout < 18000, default="
  				__MODULE_STRING(WATCHDOG_TIMEOUT) ")");

  static bool nowayout = WATCHDOG_NOWAYOUT;
  module_param(nowayout, bool, 0);

  MODULE_PARM_DESC(nowayout,
  		"Watchdog cannot be stopped once started (default="
  				__MODULE_STRING(WATCHDOG_NOWAYOUT) ")");

  
  /*
   *	ali_start	-	start watchdog countdown
   *
   *	Starts the timer running providing the timer has a counter
   *	configuration set.
   */
  
  static void ali_start(void)
  {
  	u32 val;
  
  	spin_lock(&ali_lock);
  
  	pci_read_config_dword(ali_pci, 0xCC, &val);
  	val &= ~0x3F;	/* Mask count */

  	val |= (1 << 25) | ali_timeout_bits;

  	pci_write_config_dword(ali_pci, 0xCC, val);
  
  	spin_unlock(&ali_lock);
  }
  
  /*
   *	ali_stop	-	stop the timer countdown
   *
   *	Stop the ALi watchdog countdown
   */
  
  static void ali_stop(void)
  {
  	u32 val;
  
  	spin_lock(&ali_lock);
  
  	pci_read_config_dword(ali_pci, 0xCC, &val);

  	val &= ~0x3F;		/* Mask count to zero (disabled) */
  	val &= ~(1 << 25);	/* and for safety mask the reset enable */

  	pci_write_config_dword(ali_pci, 0xCC, val);
  
  	spin_unlock(&ali_lock);
  }
  
  /*
   *	ali_keepalive	-	send a keepalive to the watchdog
   *

   *	Send a keepalive to the timer (actually we restart the timer).

   */
  
  static void ali_keepalive(void)
  {
  	ali_start();
  }
  
  /*
   *	ali_settimer	-	compute the timer reload value
   *	@t: time in seconds
   *
   *	Computes the timeout values needed
   */
  
  static int ali_settimer(int t)
  {

  	if (t < 0)

  		return -EINVAL;

  	else if (t < 60)

  		ali_timeout_bits = t|(1 << 6);

  	else if (t < 3600)

  		ali_timeout_bits = (t / 60)|(1 << 7);

  	else if (t < 18000)

  		ali_timeout_bits = (t / 300)|(1 << 6)|(1 << 7);

  	else
  		return -EINVAL;

  
  	timeout = t;
  	return 0;
  }
  
  /*
   *	/dev/watchdog handling
   */
  
  /*
   *	ali_write	-	writes to ALi watchdog
   *	@file: file from VFS
   *	@data: user address of data
   *	@len: length of data
   *	@ppos: pointer to the file offset
   *
   *	Handle a write to the ALi watchdog. Writing to the file pings
   *	the watchdog and resets it. Writing the magic 'V' sequence allows
   *	the next close to turn off the watchdog.
   */
  
  static ssize_t ali_write(struct file *file, const char __user *data,

  						size_t len, loff_t *ppos)

  {
  	/* See if we got the magic character 'V' and reload the timer */
  	if (len) {
  		if (!nowayout) {
  			size_t i;

  			/* note: just in case someone wrote the
  			   magic character five months ago... */

  			ali_expect_release = 0;

  			/* scan to see whether or not we got
  			   the magic character */

  			for (i = 0; i != len; i++) {
  				char c;

  				if (get_user(c, data + i))

  					return -EFAULT;
  				if (c == 'V')
  					ali_expect_release = 42;
  			}
  		}
  
  		/* someone wrote to us, we should reload the timer */
  		ali_start();
  	}
  	return len;
  }
  
  /*
   *	ali_ioctl	-	handle watchdog ioctls

   *	@file: VFS file pointer
   *	@cmd: ioctl number
   *	@arg: arguments to the ioctl
   *
   *	Handle the watchdog ioctls supported by the ALi driver. Really
   *	we want an extension to enable irq ack monitoring and the like
   */

  static long ali_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 =	0,
  		.identity =		"ALi M1535 WatchDog Timer",
  	};
  
  	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) {
  			ali_stop();
  			retval = 0;

  		}

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

  		}

  		return retval;
  	}

  	case WDIOC_KEEPALIVE:
  		ali_keepalive();
  		return 0;

  	case WDIOC_SETTIMEOUT:
  	{
  		int new_timeout;
  		if (get_user(new_timeout, p))
  			return -EFAULT;
  		if (ali_settimer(new_timeout))
  			return -EINVAL;
  		ali_keepalive();
  		/* Fall */
  	}
  	case WDIOC_GETTIMEOUT:
  		return put_user(timeout, p);
  	default:
  		return -ENOTTY;

  	}
  }
  
  /*
   *	ali_open	-	handle open of ali watchdog
   *	@inode: inode from VFS
   *	@file: file from VFS
   *
   *	Open the ALi watchdog device. Ensure only one person opens it
   *	at a time. Also start the watchdog running.
   */
  
  static int ali_open(struct inode *inode, struct file *file)
  {
  	/* /dev/watchdog can only be opened once */
  	if (test_and_set_bit(0, &ali_is_open))
  		return -EBUSY;
  
  	/* Activate */
  	ali_start();
  	return nonseekable_open(inode, file);
  }
  
  /*
   *	ali_release	-	close an ALi watchdog
   *	@inode: inode from VFS
   *	@file: file from VFS
   *
   *	Close the ALi watchdog device. Actual shutdown of the timer
   *	only occurs if the magic sequence has been set.
   */
  
  static int ali_release(struct inode *inode, struct file *file)
  {
  	/*
  	 *      Shut off the timer.
  	 */

  	if (ali_expect_release == 42)

  		ali_stop();

  	else {

  		pr_crit("Unexpected close, not stopping watchdog!
  ");

  		ali_keepalive();
  	}
  	clear_bit(0, &ali_is_open);
  	ali_expect_release = 0;
  	return 0;
  }
  
  /*
   *	ali_notify_sys	-	System down notifier
   *
   *	Notifier for system down
   */

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

  {

  	if (code == SYS_DOWN || code == SYS_HALT)
  		ali_stop();		/* Turn the WDT off */

  	return NOTIFY_DONE;
  }
  
  /*
   *	Data for PCI driver interface
   *
   *	This data only exists for exporting the supported
   *	PCI ids via MODULE_DEVICE_TABLE.  We do not actually
   *	register a pci_driver, because someone else might one day
   *	want to register another driver on the same PCI id.
   */

  static const struct pci_device_id ali_pci_tbl[] __used = {

  	{ PCI_VENDOR_ID_AL, 0x1533, PCI_ANY_ID, PCI_ANY_ID,},

  	{ PCI_VENDOR_ID_AL, 0x1535, PCI_ANY_ID, PCI_ANY_ID,},

  	{ 0, },
  };
  MODULE_DEVICE_TABLE(pci, ali_pci_tbl);
  
  /*
   *	ali_find_watchdog	-	find a 1535 and 7101
   *
   *	Scans the PCI hardware for a 1535 series bridge and matching 7101
   *	watchdog device. This may be overtight but it is better to be safe
   */
  
  static int __init ali_find_watchdog(void)
  {
  	struct pci_dev *pdev;
  	u32 wdog;

  	/* Check for a 1533/1535 series bridge */

  	pdev = pci_get_device(PCI_VENDOR_ID_AL, 0x1535, NULL);

  	if (pdev == NULL)
  		pdev = pci_get_device(PCI_VENDOR_ID_AL, 0x1533, NULL);
  	if (pdev == NULL)

  		return -ENODEV;

  	pci_dev_put(pdev);

  
  	/* Check for the a 7101 PMU */

  	pdev = pci_get_device(PCI_VENDOR_ID_AL, 0x7101, NULL);

  	if (pdev == NULL)

  		return -ENODEV;

  	if (pci_enable_device(pdev)) {

  		pci_dev_put(pdev);

  		return -EIO;

  	}

  
  	ali_pci = pdev;
  
  	/*
  	 *	Initialize the timer bits
  	 */
  	pci_read_config_dword(pdev, 0xCC, &wdog);

  	/* Timer bits */
  	wdog &= ~0x3F;
  	/* Issued events */

  	wdog &= ~((1 << 27)|(1 << 26)|(1 << 25)|(1 << 24));

  	/* No monitor bits */

  	wdog &= ~((1 << 16)|(1 << 13)|(1 << 12)|(1 << 11)|(1 << 10)|(1 << 9));

  
  	pci_write_config_dword(pdev, 0xCC, wdog);
  
  	return 0;
  }
  
  /*
   *	Kernel Interfaces
   */

  static const struct file_operations ali_fops = {

  	.owner		=	THIS_MODULE,
  	.llseek		=	no_llseek,

  	.write		=	ali_write,
  	.unlocked_ioctl =	ali_ioctl,

  	.open		=	ali_open,
  	.release	=	ali_release,

  };
  
  static struct miscdevice ali_miscdev = {
  	.minor =	WATCHDOG_MINOR,
  	.name =		"watchdog",
  	.fops =		&ali_fops,
  };
  
  static struct notifier_block ali_notifier = {
  	.notifier_call =	ali_notify_sys,
  };
  
  /*
   *	watchdog_init	-	module initialiser
   *
   *	Scan for a suitable watchdog and if so initialize it. Return an error
   *	if we cannot, the error causes the module to unload
   */
  
  static int __init watchdog_init(void)
  {
  	int ret;

  	/* Check whether or not the hardware watchdog is there */

  	if (ali_find_watchdog() != 0)

  		return -ENODEV;

  	/* Check that the timeout value is within it's range;
  	   if not reset to the default */

  	if (timeout < 1 || timeout >= 18000) {
  		timeout = WATCHDOG_TIMEOUT;

  		pr_info("timeout value must be 0 < timeout < 18000, using %d
  ",
  			timeout);

  	}
  
  	/* Calculate the watchdog's timeout */
  	ali_settimer(timeout);

  	ret = register_reboot_notifier(&ali_notifier);

  	if (ret != 0) {

  		pr_err("cannot register reboot notifier (err=%d)
  ", ret);

  		goto out;
  	}

  	ret = misc_register(&ali_miscdev);

  	if (ret != 0) {

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

  		goto unreg_reboot;

  	}

  	pr_info("initialized. timeout=%d sec (nowayout=%d)
  ",

  		timeout, nowayout);
  
  out:
  	return ret;

  unreg_reboot:
  	unregister_reboot_notifier(&ali_notifier);

  	goto out;
  }
  
  /*
   *	watchdog_exit	-	module de-initialiser
   *
   *	Called while unloading a successfully installed watchdog module.
   */
  
  static void __exit watchdog_exit(void)
  {
  	/* Stop the timer before we leave */
  	ali_stop();
  
  	/* Deregister */

  	misc_deregister(&ali_miscdev);

  	unregister_reboot_notifier(&ali_notifier);

  	pci_dev_put(ali_pci);

  }
  
  module_init(watchdog_init);
  module_exit(watchdog_exit);
  
  MODULE_AUTHOR("Alan Cox");
  MODULE_DESCRIPTION("ALi M1535 PMU Watchdog Timer driver");
  MODULE_LICENSE("GPL");