/*
 *      Wdt977  0.04:   A Watchdog Device for Netwinder W83977AF chip
 *
 *      (c) Copyright 1998 Rebel.com (Woody Suwalski <woody@netwinder.org>)
 *
 *                      -----------------------
 *
 *      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.
 *
 *                      -----------------------
 *      14-Dec-2001 Matt Domsch <Matt_Domsch@dell.com>
 *           Added nowayout module option to override CONFIG_WATCHDOG_NOWAYOUT
 *      19-Dec-2001 Woody Suwalski: Netwinder fixes, ioctl interface
 *      06-Jan-2002 Woody Suwalski: For compatibility, convert all timeouts
 *                                  from minutes to seconds.
 *      07-Jul-2003 Daniele Bellucci: Audit return code of misc_register in
 *                                    nwwatchdog_init.
 *      25-Oct-2005 Woody Suwalski: Convert addresses to #defs, add spinlocks
 *                                  remove limitiation to be used on
 *                                  Netwinders only
 */

#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt

#include <linux/module.h>
#include <linux/moduleparam.h>
#include <linux/types.h>
#include <linux/kernel.h>
#include <linux/fs.h>
#include <linux/miscdevice.h>
#include <linux/init.h>
#include <linux/ioport.h>
#include <linux/watchdog.h>
#include <linux/notifier.h>
#include <linux/reboot.h>
#include <linux/io.h>
#include <linux/uaccess.h>

#include <asm/mach-types.h>

#define WATCHDOG_VERSION  "0.04"
#define WATCHDOG_NAME     "Wdt977"

#define IO_INDEX_PORT   0x370           /* on some systems it can be 0x3F0 */
#define IO_DATA_PORT    (IO_INDEX_PORT + 1)

#define UNLOCK_DATA     0x87
#define LOCK_DATA       0xAA
#define DEVICE_REGISTER 0x07


#define DEFAULT_TIMEOUT 60                      /* default timeout in seconds */

static  int timeout = DEFAULT_TIMEOUT;
static  int timeoutM;                           /* timeout in minutes */
static  unsigned long timer_alive;
static  int testmode;
static  char expect_close;
static  DEFINE_SPINLOCK(spinlock);

module_param(timeout, int, 0);
MODULE_PARM_DESC(timeout, "Watchdog timeout in seconds (60..15300, default="
                                __MODULE_STRING(DEFAULT_TIMEOUT) ")");
module_param(testmode, int, 0);
MODULE_PARM_DESC(testmode, "Watchdog testmode (1 = no reboot), default=0");

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) ")");

/*
 * Start the watchdog
 */

static int wdt977_start(void)
{
        unsigned long flags;

        spin_lock_irqsave(&spinlock, flags);

        /* unlock the SuperIO chip */
        outb_p(UNLOCK_DATA, IO_INDEX_PORT);
        outb_p(UNLOCK_DATA, IO_INDEX_PORT);

        /* select device Aux2 (device=8) and set watchdog regs F2, F3 and F4
         * F2 has the timeout in minutes
         * F3 could be set to the POWER LED blink (with GP17 set to PowerLed)
         *   at timeout, and to reset timer on kbd/mouse activity (not impl.)
         * F4 is used to just clear the TIMEOUT'ed state (bit 0)
         */
        outb_p(DEVICE_REGISTER, IO_INDEX_PORT);
        outb_p(0x08, IO_DATA_PORT);
        outb_p(0xF2, IO_INDEX_PORT);
        outb_p(timeoutM, IO_DATA_PORT);
        outb_p(0xF3, IO_INDEX_PORT);
        outb_p(0x00, IO_DATA_PORT);     /* another setting is 0E for
                                           kbd/mouse/LED */
        outb_p(0xF4, IO_INDEX_PORT);
        outb_p(0x00, IO_DATA_PORT);

        /* At last select device Aux1 (dev=7) and set GP16 as a
         * watchdog output. In test mode watch the bit 1 on F4 to
         * indicate "triggered"
         */
        if (!testmode) {
                outb_p(DEVICE_REGISTER, IO_INDEX_PORT);
                outb_p(0x07, IO_DATA_PORT);
                outb_p(0xE6, IO_INDEX_PORT);
                outb_p(0x08, IO_DATA_PORT);
        }

        /* lock the SuperIO chip */
        outb_p(LOCK_DATA, IO_INDEX_PORT);

        spin_unlock_irqrestore(&spinlock, flags);
        pr_info("activated\n");

        return 0;
}

/*
 * Stop the watchdog
 */

static int wdt977_stop(void)
{
        unsigned long flags;
        spin_lock_irqsave(&spinlock, flags);

        /* unlock the SuperIO chip */
        outb_p(UNLOCK_DATA, IO_INDEX_PORT);
        outb_p(UNLOCK_DATA, IO_INDEX_PORT);

        /* select device Aux2 (device=8) and set watchdog regs F2,F3 and F4
        * F3 is reset to its default state
        * F4 can clear the TIMEOUT'ed state (bit 0) - back to default
        * We can not use GP17 as a PowerLed, as we use its usage as a RedLed
        */
        outb_p(DEVICE_REGISTER, IO_INDEX_PORT);
        outb_p(0x08, IO_DATA_PORT);
        outb_p(0xF2, IO_INDEX_PORT);
        outb_p(0xFF, IO_DATA_PORT);
        outb_p(0xF3, IO_INDEX_PORT);
        outb_p(0x00, IO_DATA_PORT);
        outb_p(0xF4, IO_INDEX_PORT);
        outb_p(0x00, IO_DATA_PORT);
        outb_p(0xF2, IO_INDEX_PORT);
        outb_p(0x00, IO_DATA_PORT);

        /* at last select device Aux1 (dev=7) and set
           GP16 as a watchdog output */
        outb_p(DEVICE_REGISTER, IO_INDEX_PORT);
        outb_p(0x07, IO_DATA_PORT);
        outb_p(0xE6, IO_INDEX_PORT);
        outb_p(0x08, IO_DATA_PORT);

        /* lock the SuperIO chip */
        outb_p(LOCK_DATA, IO_INDEX_PORT);

        spin_unlock_irqrestore(&spinlock, flags);
        pr_info("shutdown\n");

        return 0;
}

/*
 * Send a keepalive ping to the watchdog
 * This is done by simply re-writing the timeout to reg. 0xF2
 */

static int wdt977_keepalive(void)
{
        unsigned long flags;
        spin_lock_irqsave(&spinlock, flags);

        /* unlock the SuperIO chip */
        outb_p(UNLOCK_DATA, IO_INDEX_PORT);
        outb_p(UNLOCK_DATA, IO_INDEX_PORT);

        /* select device Aux2 (device=8) and kicks watchdog reg F2 */
        /* F2 has the timeout in minutes */
        outb_p(DEVICE_REGISTER, IO_INDEX_PORT);
        outb_p(0x08, IO_DATA_PORT);
        outb_p(0xF2, IO_INDEX_PORT);
        outb_p(timeoutM, IO_DATA_PORT);

        /* lock the SuperIO chip */
        outb_p(LOCK_DATA, IO_INDEX_PORT);
        spin_unlock_irqrestore(&spinlock, flags);

        return 0;
}

/*
 * Set the watchdog timeout value
 */

static int wdt977_set_timeout(int t)
{
        int tmrval;

        /* convert seconds to minutes, rounding up */
        tmrval = (t + 59) / 60;

        if (machine_is_netwinder()) {
                /* we have a hw bug somewhere, so each 977 minute is actually
                 * only 30sec. This limits the max timeout to half of device
                 * max of 255 minutes...
                 */
                tmrval += tmrval;
        }

        if (tmrval < 1 || tmrval > 255)
                return -EINVAL;

        /* timeout is the timeout in seconds, timeoutM is
           the timeout in minutes) */
        timeout = t;
        timeoutM = tmrval;
        return 0;
}

/*
 * Get the watchdog status
 */

static int wdt977_get_status(int *status)
{
        int new_status;
        unsigned long flags;

        spin_lock_irqsave(&spinlock, flags);

        /* unlock the SuperIO chip */
        outb_p(UNLOCK_DATA, IO_INDEX_PORT);
        outb_p(UNLOCK_DATA, IO_INDEX_PORT);

        /* select device Aux2 (device=8) and read watchdog reg F4 */
        outb_p(DEVICE_REGISTER, IO_INDEX_PORT);
        outb_p(0x08, IO_DATA_PORT);
        outb_p(0xF4, IO_INDEX_PORT);
        new_status = inb_p(IO_DATA_PORT);

        /* lock the SuperIO chip */
        outb_p(LOCK_DATA, IO_INDEX_PORT);

        spin_unlock_irqrestore(&spinlock, flags);

        *status = 0;
        if (new_status & 1)
                *status |= WDIOF_CARDRESET;

        return 0;
}


/*
 *      /dev/watchdog handling
 */

static int wdt977_open(struct inode *inode, struct file *file)
{
        /* If the watchdog is alive we don't need to start it again */
        if (test_and_set_bit(0, &timer_alive))
                return -EBUSY;

        if (nowayout)
                __module_get(THIS_MODULE);

        wdt977_start();
        return nonseekable_open(inode, file);
}

static int wdt977_release(struct inode *inode, struct file *file)
{
        /*
         *      Shut off the timer.
         *      Lock it in if it's a module and we set nowayout
         */
        if (expect_close == 42) {
                wdt977_stop();
                clear_bit(0, &timer_alive);
        } else {
                wdt977_keepalive();
                pr_crit("Unexpected close, not stopping watchdog!\n");
        }
        expect_close = 0;
        return 0;
}


/*
 *      wdt977_write:
 *      @file: file handle to the watchdog
 *      @buf: buffer to write (unused as data does not matter here
 *      @count: count of bytes
 *      @ppos: pointer to the position to write. No seeks allowed
 *
 *      A write to a watchdog device is defined as a keepalive signal. Any
 *      write of data will do, as we we don't define content meaning.
 */

static ssize_t wdt977_write(struct file *file, const char __user *buf,
                            size_t count, loff_t *ppos)
{
        if (count) {
                if (!nowayout) {
                        size_t i;

                        /* In case it was set long ago */
                        expect_close = 0;

                        for (i = 0; i != count; i++) {
                                char c;
                                if (get_user(c, buf + i))
                                        return -EFAULT;
                                if (c == 'V')
                                        expect_close = 42;
                        }
                }

                /* someone wrote to us, we should restart timer */
                wdt977_keepalive();
        }
        return count;
}

static const struct watchdog_info ident = {
        .options =              WDIOF_SETTIMEOUT |
                                WDIOF_MAGICCLOSE |
                                WDIOF_KEEPALIVEPING,
        .firmware_version =     1,
        .identity =             WATCHDOG_NAME,
};

/*
 *      wdt977_ioctl:
 *      @inode: inode of the device
 *      @file: file handle to the device
 *      @cmd: watchdog command
 *      @arg: argument pointer
 *
 *      The watchdog API defines a common set of functions for all watchdogs
 *      according to their available features.
 */

static long wdt977_ioctl(struct file *file, unsigned int cmd,
                                                        unsigned long arg)
{
        int status;
        int new_options, retval = -EINVAL;
        int new_timeout;
        union {
                struct watchdog_info __user *ident;
                int __user *i;
        } uarg;

        uarg.i = (int __user *)arg;

        switch (cmd) {
        case WDIOC_GETSUPPORT:
                return copy_to_user(uarg.ident, &ident,
                        sizeof(ident)) ? -EFAULT : 0;

        case WDIOC_GETSTATUS:
                wdt977_get_status(&status);
                return put_user(status, uarg.i);

        case WDIOC_GETBOOTSTATUS:
                return put_user(0, uarg.i);

        case WDIOC_SETOPTIONS:
                if (get_user(new_options, uarg.i))
                        return -EFAULT;

                if (new_options & WDIOS_DISABLECARD) {
                        wdt977_stop();
                        retval = 0;
                }

                if (new_options & WDIOS_ENABLECARD) {
                        wdt977_start();
                        retval = 0;
                }

                return retval;

        case WDIOC_KEEPALIVE:
                wdt977_keepalive();
                return 0;

        case WDIOC_SETTIMEOUT:
                if (get_user(new_timeout, uarg.i))
                        return -EFAULT;

                if (wdt977_set_timeout(new_timeout))
                        return -EINVAL;

                wdt977_keepalive();
                /* Fall */

        case WDIOC_GETTIMEOUT:
                return put_user(timeout, uarg.i);

        default:
                return -ENOTTY;

        }
}

static int wdt977_notify_sys(struct notifier_block *this, unsigned long code,
        void *unused)
{
        if (code == SYS_DOWN || code == SYS_HALT)
                wdt977_stop();
        return NOTIFY_DONE;
}

static const struct file_operations wdt977_fops = {
        .owner          = THIS_MODULE,
        .llseek         = no_llseek,
        .write          = wdt977_write,
        .unlocked_ioctl = wdt977_ioctl,
        .open           = wdt977_open,
        .release        = wdt977_release,
};

static struct miscdevice wdt977_miscdev = {
        .minor          = WATCHDOG_MINOR,
        .name           = "watchdog",
        .fops           = &wdt977_fops,
};

static struct notifier_block wdt977_notifier = {
        .notifier_call = wdt977_notify_sys,
};

static int __init wd977_init(void)
{
        int rc;

        pr_info("driver v%s\n", WATCHDOG_VERSION);

        /* Check that the timeout value is within its range;
           if not reset to the default */
        if (wdt977_set_timeout(timeout)) {
                wdt977_set_timeout(DEFAULT_TIMEOUT);
                pr_info("timeout value must be 60 < timeout < 15300, using %d\n",
                        DEFAULT_TIMEOUT);
        }

        /* on Netwinder the IOports are already reserved by
         * arch/arm/mach-footbridge/netwinder-hw.c
         */
        if (!machine_is_netwinder()) {
                if (!request_region(IO_INDEX_PORT, 2, WATCHDOG_NAME)) {
                        pr_err("I/O address 0x%04x already in use\n",
                               IO_INDEX_PORT);
                        rc = -EIO;
                        goto err_out;
                }
        }

        rc = register_reboot_notifier(&wdt977_notifier);
        if (rc) {
                pr_err("cannot register reboot notifier (err=%d)\n", rc);
                goto err_out_region;
        }

        rc = misc_register(&wdt977_miscdev);
        if (rc) {
                pr_err("cannot register miscdev on minor=%d (err=%d)\n",
                       wdt977_miscdev.minor, rc);
                goto err_out_reboot;
        }

        pr_info("initialized. timeout=%d sec (nowayout=%d, testmode=%i)\n",
                timeout, nowayout, testmode);

        return 0;

err_out_reboot:
        unregister_reboot_notifier(&wdt977_notifier);
err_out_region:
        if (!machine_is_netwinder())
                release_region(IO_INDEX_PORT, 2);
err_out:
        return rc;
}

static void __exit wd977_exit(void)
{
        wdt977_stop();
        misc_deregister(&wdt977_miscdev);
        unregister_reboot_notifier(&wdt977_notifier);
        release_region(IO_INDEX_PORT, 2);
}

module_init(wd977_init);
module_exit(wd977_exit);

MODULE_AUTHOR("Woody Suwalski <woodys@xandros.com>");
MODULE_DESCRIPTION("W83977AF Watchdog driver");
MODULE_LICENSE("GPL");
MODULE_ALIAS_MISCDEV(WATCHDOG_MINOR);