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  /*
   *        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 <linux/uaccess.h>
 #include <linux/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 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 int nowayout = WATCHDOG_NOWAYOUT;
 module_param(nowayout, int, 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 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 {
                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)
                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 struct pci_device_id ali_pci_tbl[] = {
        { 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;
                printk(KERN_INFO PFX
                     "timeout value must be 0 < timeout < 18000, using %d\n",
                                                        timeout);
        }

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

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

        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 unreg_reboot;
        }

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