/*
 *	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.
 */

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

#define WATCHDOG_NAME "ALi_M1535"
#define PFX WATCHDOG_NAME ": "
#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 spinlock_t 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 int nowayout = WATCHDOG_NOWAYOUT;
module_param(nowayout, int, 0);
MODULE_PARM_DESC(nowayout, "Watchdog cannot be stopped once started (default=CONFIG_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
 *	@inode: VFS inode
 *	@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 int ali_ioctl(struct inode *inode, struct file *file,
			  unsigned int cmd, unsigned long arg)
{
	void __user *argp = (void __user *)arg;
	int __user *p = argp;
	static 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_KEEPALIVE:
			ali_keepalive();
			return 0;

		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_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 -ENOIOCTLCMD;
	}
}

/*
 *	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 {
		printk(KERN_CRIT PFX "Unexpected close, not stopping watchdog!\n");
		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) {
		/* Turn the WDT off */
		ali_stop();
	}

	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 struct pci_device_id ali_pci_tbl[] = {
	{ 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 1535 series bridge */
	pdev = pci_find_device(PCI_VENDOR_ID_AL, 0x1535, NULL);
	if(pdev == NULL)
		return -ENODEV;

	/* Check for the a 7101 PMU */
	pdev = pci_find_device(PCI_VENDOR_ID_AL, 0x7101, NULL);
	if(pdev == NULL)
		return -ENODEV;

	if(pci_enable_device(pdev))
		return -EIO;

	ali_pci = pdev;

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

	wdog &= ~0x3F;		/* Timer bits */
	wdog &= ~((1<<27)|(1<<26)|(1<<25)|(1<<24));	/* Issued events */
	wdog &= ~((1<<16)|(1<<13)|(1<<12)|(1<<11)|(1<<10)|(1<<9));	/* No monitor bits */

	pci_write_config_dword(pdev, 0xCC, wdog);

	return 0;
}

/*
 *	Kernel Interfaces
 */

static struct file_operations ali_fops = {
	.owner =	THIS_MODULE,
	.llseek =	no_llseek,
	.write =	ali_write,
	.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;

	spin_lock_init(&ali_lock);

	/* 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;
		printk(KERN_INFO PFX "timeout value must be 0<timeout<18000, using %d\n",
			timeout);
	}

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

	ret = misc_register(&ali_miscdev);
	if (ret != 0) {
		printk(KERN_ERR PFX "cannot register miscdev on minor=%d (err=%d)\n",
			WATCHDOG_MINOR, ret);
		goto out;
	}

	ret = register_reboot_notifier(&ali_notifier);
	if (ret != 0) {
		printk(KERN_ERR PFX "cannot register reboot notifier (err=%d)\n",
			ret);
		goto unreg_miscdev;
	}

	printk(KERN_INFO PFX "initialized. timeout=%d sec (nowayout=%d)\n",
		timeout, nowayout);

out:
	return ret;
unreg_miscdev:
	misc_deregister(&ali_miscdev);
	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 */
	unregister_reboot_notifier(&ali_notifier);
	misc_deregister(&ali_miscdev);
}

module_init(watchdog_init);
module_exit(watchdog_exit);

MODULE_AUTHOR("Alan Cox");
MODULE_DESCRIPTION("ALi M1535 PMU Watchdog Timer driver");
MODULE_LICENSE("GPL");
MODULE_ALIAS_MISCDEV(WATCHDOG_MINOR);