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/*

 *      SMsC 37B787 Watchdog Timer driver for Linux 2.6.x.x

 *

 *      Based on acquirewdt.c by Alan Cox <alan@redhat.com>

 *       and some other existing drivers

 *

 *      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.

 *

 *      The authors do NOT admit liability nor provide warranty for

 *      any of this software. This material is provided "AS-IS" in

 *      the hope that it may be useful for others.

 *

 *      (C) Copyright 2003-2006  Sven Anders <anders@anduras.de>

 *

 *  History:

 *      2003 - Created version 1.0 for Linux 2.4.x.

 *      2006 - Ported to Linux 2.6, added nowayout and MAGICCLOSE

 *             features. Released version 1.1

 *

 *  Theory of operation:

 *

 *      A Watchdog Timer (WDT) is a hardware circuit that can

 *      reset the computer system in case of a software fault.

 *      You probably knew that already.

 *

 *      Usually a userspace daemon will notify the kernel WDT driver

 *      via the /dev/watchdog special device file that userspace is

 *      still alive, at regular intervals.  When such a notification

 *      occurs, the driver will usually tell the hardware watchdog

 *      that everything is in order, and that the watchdog should wait

 *      for yet another little while to reset the system.

 *      If userspace fails (RAM error, kernel bug, whatever), the

 *      notifications cease to occur, and the hardware watchdog will

 *      reset the system (causing a reboot) after the timeout occurs.

 *

 * Create device with:

 *  mknod /dev/watchdog c 10 130

 *

 * For an example userspace keep-alive daemon, see:

 *   Documentation/watchdog/watchdog.txt

 */

#include <linux/module.h>

#include <linux/moduleparam.h>

#include <linux/types.h>

#include <linux/miscdevice.h>

#include <linux/watchdog.h>

#include <linux/delay.h>

#include <linux/fs.h>

#include <linux/ioport.h>

#include <linux/notifier.h>

#include <linux/reboot.h>

#include <linux/init.h>

#include <linux/spinlock.h>

#include <asm/io.h>

#include <asm/uaccess.h>

#include <asm/system.h>

/* enable support for minutes as units? */

/* (does not always work correctly, so disabled by default!) */

#define SMSC_SUPPORT_MINUTES

#undef SMSC_SUPPORT_MINUTES

#define MAX_TIMEOUT     255

#define UNIT_SECOND     0

#define UNIT_MINUTE     1

#define MODNAME         "smsc37b787_wdt: "

#define VERSION         "1.1"

#define IOPORT          0x3F0

#define IOPORT_SIZE     2

#define IODEV_NO        8

static int unit = UNIT_SECOND;  /* timer's unit */

static int timeout = 60;        /* timeout value: default is 60 "units" */

static unsigned long timer_enabled = 0;   /* is the timer enabled? */

static char expect_close;       /* is the close expected? */

static DEFINE_SPINLOCK(io_lock);/* to guard the watchdog from io races */

static int nowayout = WATCHDOG_NOWAYOUT;

/* -- Low level function ----------------------------------------*/

/* unlock the IO chip */

static inline void open_io_config(void)

{

        outb(0x55, IOPORT);

        mdelay(1);

        outb(0x55, IOPORT);

}

/* lock the IO chip */

static inline void close_io_config(void)

{

        outb(0xAA, IOPORT);

}

/* select the IO device */

static inline void select_io_device(unsigned char devno)

{

        outb(0x07, IOPORT);

        outb(devno, IOPORT+1);

}

/* write to the control register */

static inline void write_io_cr(unsigned char reg, unsigned char data)

{

        outb(reg, IOPORT);

        outb(data, IOPORT+1);

}

/* read from the control register */

static inline char read_io_cr(unsigned char reg)

{

        outb(reg, IOPORT);

        return inb(IOPORT+1);

}

/* -- Medium level functions ------------------------------------*/

static inline void gpio_bit12(unsigned char reg)

{

        // -- General Purpose I/O Bit 1.2 --

        // Bit 0,   In/Out: 0 = Output, 1 = Input

        // Bit 1,   Polarity: 0 = No Invert, 1 = Invert

        // Bit 2,   Group Enable Intr.: 0 = Disable, 1 = Enable

        // Bit 3/4, Function select: 00 = GPI/O, 01 = WDT, 10 = P17,

        //                           11 = Either Edge Triggered Intr. 2

        // Bit 5/6  (Reserved)

        // Bit 7,   Output Type: 0 = Push Pull Bit, 1 = Open Drain

        write_io_cr(0xE2, reg);

}

static inline void gpio_bit13(unsigned char reg)

{

        // -- General Purpose I/O Bit 1.3 --

        // Bit 0,  In/Out: 0 = Output, 1 = Input

        // Bit 1,  Polarity: 0 = No Invert, 1 = Invert

        // Bit 2,  Group Enable Intr.: 0 = Disable, 1 = Enable

        // Bit 3,  Function select: 0 = GPI/O, 1 = LED

        // Bit 4-6 (Reserved)

        // Bit 7,  Output Type: 0 = Push Pull Bit, 1 = Open Drain

        write_io_cr(0xE3, reg);

}

static inline void wdt_timer_units(unsigned char new_units)

{

        // -- Watchdog timer units --

        // Bit 0-6 (Reserved)

        // Bit 7,  WDT Time-out Value Units Select

        //         (0 = Minutes, 1 = Seconds)

        write_io_cr(0xF1, new_units);

}

static inline void wdt_timeout_value(unsigned char new_timeout)

{

        // -- Watchdog Timer Time-out Value --

        // Bit 0-7 Binary coded units (0=Disabled, 1..255)

        write_io_cr(0xF2, new_timeout);

}

static inline void wdt_timer_conf(unsigned char conf)

{

        // -- Watchdog timer configuration --

        // Bit 0   Joystick enable: 0* = No Reset, 1 = Reset WDT upon Gameport I/O

        // Bit 1   Keyboard enable: 0* = No Reset, 1 = Reset WDT upon KBD Intr.

        // Bit 2   Mouse enable: 0* = No Reset, 1 = Reset WDT upon Mouse Intr.

        // Bit 3   Reset the timer

        //         (Wrong in SMsC documentation? Given as: PowerLED Timout Enabled)

        // Bit 4-7 WDT Interrupt Mapping: (0000* = Disabled,

        //            0001=IRQ1, 0010=(Invalid), 0011=IRQ3 to 1111=IRQ15)

        write_io_cr(0xF3, conf);

}

static inline void wdt_timer_ctrl(unsigned char reg)

{

        // -- Watchdog timer control --

        // Bit 0   Status Bit: 0 = Timer counting, 1 = Timeout occured

        // Bit 1   Power LED Toggle: 0 = Disable Toggle, 1 = Toggle at 1 Hz

        // Bit 2   Force Timeout: 1 = Forces WD timeout event (self-cleaning)

        // Bit 3   P20 Force Timeout enabled:

        //          0 = P20 activity does not generate the WD timeout event

        //          1 = P20 Allows rising edge of P20, from the keyboard

        //              controller, to force the WD timeout event.

        // Bit 4   (Reserved)

        // -- Soft power management --

        // Bit 5   Stop Counter: 1 = Stop software power down counter

        //            set via register 0xB8, (self-cleaning)

        //            (Upon read: 0 = Counter running, 1 = Counter stopped)

        // Bit 6   Restart Counter: 1 = Restart software power down counter

        //            set via register 0xB8, (self-cleaning)

        // Bit 7   SPOFF: 1 = Force software power down (self-cleaning)

        write_io_cr(0xF4, reg);

}

/* -- Higher level functions ------------------------------------*/

/* initialize watchdog */

static void wb_smsc_wdt_initialize(void)

{

        unsigned char old;

        spin_lock(&io_lock);

        open_io_config();

        select_io_device(IODEV_NO);

        // enable the watchdog

        gpio_bit13(0x08);  // Select pin 80 = LED not GPIO

        gpio_bit12(0x0A);  // Set pin 79 = WDT not GPIO/Output/Polarity=Invert

        // disable the timeout

        wdt_timeout_value(0);

        // reset control register

        wdt_timer_ctrl(0x00);

        // reset configuration register

        wdt_timer_conf(0x00);

        // read old (timer units) register

        old = read_io_cr(0xF1) & 0x7F;

        if (unit == UNIT_SECOND) old |= 0x80; // set to seconds

        // set the watchdog timer units

        wdt_timer_units(old);

        close_io_config();

        spin_unlock(&io_lock);

}

/* shutdown the watchdog */

static void wb_smsc_wdt_shutdown(void)

{

        spin_lock(&io_lock);

        open_io_config();

        select_io_device(IODEV_NO);

        // disable the watchdog

        gpio_bit13(0x09);

        gpio_bit12(0x09);

        // reset watchdog config register

        wdt_timer_conf(0x00);

        // reset watchdog control register

        wdt_timer_ctrl(0x00);

        // disable timeout

        wdt_timeout_value(0x00);

        close_io_config();

        spin_unlock(&io_lock);

}

/* set timeout => enable watchdog */

static void wb_smsc_wdt_set_timeout(unsigned char new_timeout)

{

        spin_lock(&io_lock);

        open_io_config();

        select_io_device(IODEV_NO);

        // set Power LED to blink, if we enable the timeout

        wdt_timer_ctrl((new_timeout == 0) ? 0x00 : 0x02);

        // set timeout value

        wdt_timeout_value(new_timeout);

        close_io_config();

        spin_unlock(&io_lock);

}

/* get timeout */

static unsigned char wb_smsc_wdt_get_timeout(void)

{

        unsigned char set_timeout;

        spin_lock(&io_lock);

        open_io_config();

        select_io_device(IODEV_NO);

        set_timeout = read_io_cr(0xF2);

        close_io_config();

        spin_unlock(&io_lock);

        return set_timeout;

}

/* disable watchdog */

static void wb_smsc_wdt_disable(void)

{

        // set the timeout to 0 to disable the watchdog

        wb_smsc_wdt_set_timeout(0);

}

/* enable watchdog by setting the current timeout */

static void wb_smsc_wdt_enable(void)

{

        // set the current timeout...

        wb_smsc_wdt_set_timeout(timeout);

}

/* reset the timer */

static void wb_smsc_wdt_reset_timer(void)

{

        spin_lock(&io_lock);

        open_io_config();

        select_io_device(IODEV_NO);

        // reset the timer

        wdt_timeout_value(timeout);

        wdt_timer_conf(0x08);

        close_io_config();

        spin_unlock(&io_lock);

}

/* return, if the watchdog is enabled (timeout is set...) */

static int wb_smsc_wdt_status(void)

{

        return (wb_smsc_wdt_get_timeout() == 0) ? 0 : WDIOF_KEEPALIVEPING;

}

/* -- File operations -------------------------------------------*/

/* open => enable watchdog and set initial timeout */

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

{

        /* /dev/watchdog can only be opened once */

        if (test_and_set_bit(0, &timer_enabled))

                return -EBUSY;

        if (nowayout)

                __module_get(THIS_MODULE);

        /* Reload and activate timer */

        wb_smsc_wdt_enable();

        printk(KERN_INFO MODNAME "Watchdog enabled. Timeout set to %d %s.\n", timeout, (unit == UNIT_SECOND) ? "second(s)" : "minute(s)");

        return nonseekable_open(inode, file);

}

/* close => shut off the timer */

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

{

        /* Shut off the timer. */

        if (expect_close == 42) {

                wb_smsc_wdt_disable();

                printk(KERN_INFO MODNAME "Watchdog disabled, sleeping again...\n");

        } else {

                printk(KERN_CRIT MODNAME "Unexpected close, not stopping watchdog!\n");

                wb_smsc_wdt_reset_timer();

        }

        clear_bit(0, &timer_enabled);

        expect_close = 0;

        return 0;

}

/* write => update the timer to keep the machine alive */

static ssize_t wb_smsc_wdt_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;

                        /* reset expect flag */

                        expect_close = 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')

                                        expect_close = 42;

                        }

                }

                /* someone wrote to us, we should reload the timer */

                wb_smsc_wdt_reset_timer();

        }

        return len;

}

/* ioctl => control interface */

static int wb_smsc_wdt_ioctl(struct inode *inode, struct file *file,

                             unsigned int cmd, unsigned long arg)

{

        int new_timeout;

        union {

                struct watchdog_info __user *ident;

                int __user *i;

        } uarg;

        static struct watchdog_info ident = {

                .options =              WDIOF_KEEPALIVEPING |

                                        WDIOF_SETTIMEOUT |

                                        WDIOF_MAGICCLOSE,

                .firmware_version =     0,

                .identity =             "SMsC 37B787 Watchdog"

        };

        uarg.i = (int __user *)arg;

        switch (cmd) {

                default:

                        return -ENOTTY;

                case WDIOC_GETSUPPORT:

                        return copy_to_user(uarg.ident, &ident,

                                sizeof(ident)) ? -EFAULT : 0;

                case WDIOC_GETSTATUS:

                        return put_user(wb_smsc_wdt_status(), uarg.i);

                case WDIOC_GETBOOTSTATUS:

                        return put_user(0, uarg.i);

                case WDIOC_KEEPALIVE:

                        wb_smsc_wdt_reset_timer();

                        return 0;

                case WDIOC_SETTIMEOUT:

                        if (get_user(new_timeout, uarg.i))

                                return -EFAULT;

                        // the API states this is given in secs

                        if (unit == UNIT_MINUTE)

                          new_timeout /= 60;

                        if (new_timeout < 0 || new_timeout > MAX_TIMEOUT)

                                return -EINVAL;

                        timeout = new_timeout;

                        wb_smsc_wdt_set_timeout(timeout);

                        // fall through and return the new timeout...

                case WDIOC_GETTIMEOUT:

                        new_timeout = timeout;

                        if (unit == UNIT_MINUTE)

                          new_timeout *= 60;

                        return put_user(new_timeout, uarg.i);

                case WDIOC_SETOPTIONS:

                {

                        int options, retval = -EINVAL;

                        if (get_user(options, uarg.i))

                                return -EFAULT;

                        if (options & WDIOS_DISABLECARD) {

                                wb_smsc_wdt_disable();

                                retval = 0;

                        }

                        if (options & WDIOS_ENABLECARD) {

                                wb_smsc_wdt_enable();

                                retval = 0;

                        }

                        return retval;

                }

        }

}

/* -- Notifier funtions -----------------------------------------*/

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

{

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

        {

                // set timeout to 0, to avoid possible race-condition

                timeout = 0;

                wb_smsc_wdt_disable();

        }

        return NOTIFY_DONE;

}

/* -- Module's structures ---------------------------------------*/

static const struct file_operations wb_smsc_wdt_fops =

{

        .owner          = THIS_MODULE,

        .llseek         = no_llseek,

        .write          = wb_smsc_wdt_write,

        .ioctl          = wb_smsc_wdt_ioctl,

        .open           = wb_smsc_wdt_open,

        .release        = wb_smsc_wdt_release,

};

static struct notifier_block wb_smsc_wdt_notifier =

{

        .notifier_call  = wb_smsc_wdt_notify_sys,

};

static struct miscdevice wb_smsc_wdt_miscdev =

{

        .minor          = WATCHDOG_MINOR,

        .name           = "watchdog",

        .fops           = &wb_smsc_wdt_fops,

};

/* -- Module init functions -------------------------------------*/

/* module's "constructor" */

static int __init wb_smsc_wdt_init(void)

{

        int ret;

        printk("SMsC 37B787 watchdog component driver " VERSION " initialising...\n");

        if (!request_region(IOPORT, IOPORT_SIZE, "SMsC 37B787 watchdog")) {

                printk(KERN_ERR MODNAME "Unable to register IO port %#x\n", IOPORT);

                ret = -EBUSY;

                goto out_pnp;

        }

        // set new maximum, if it's too big

        if (timeout > MAX_TIMEOUT)

               timeout = MAX_TIMEOUT;

        // init the watchdog timer

        wb_smsc_wdt_initialize();

        ret = register_reboot_notifier(&wb_smsc_wdt_notifier);

        if (ret) {

                printk(KERN_ERR MODNAME "Unable to register reboot notifier err = %d\n", ret);

                goto out_io;

        }

        ret = misc_register(&wb_smsc_wdt_miscdev);

        if (ret) {

                printk(KERN_ERR MODNAME "Unable to register miscdev on minor %d\n", WATCHDOG_MINOR);

                goto out_rbt;

        }

        // output info

        printk(KERN_INFO MODNAME "Timeout set to %d %s.\n", timeout, (unit == UNIT_SECOND) ? "second(s)" : "minute(s)");

        printk(KERN_INFO MODNAME "Watchdog initialized and sleeping (nowayout=%d)...\n", nowayout);

        // ret = 0

out_clean:

        return ret;

out_rbt:

        unregister_reboot_notifier(&wb_smsc_wdt_notifier);

out_io:

        release_region(IOPORT, IOPORT_SIZE);

out_pnp:

        goto out_clean;

}

/* module's "destructor" */

static void __exit wb_smsc_wdt_exit(void)

{

        /* Stop the timer before we leave */

        if (!nowayout)

        {

                wb_smsc_wdt_shutdown();

                printk(KERN_INFO MODNAME "Watchdog disabled.\n");

        }

        misc_deregister(&wb_smsc_wdt_miscdev);

        unregister_reboot_notifier(&wb_smsc_wdt_notifier);

        release_region(IOPORT, IOPORT_SIZE);

        printk("SMsC 37B787 watchdog component driver removed.\n");

}

module_init(wb_smsc_wdt_init);

module_exit(wb_smsc_wdt_exit);

MODULE_AUTHOR("Sven Anders <anders@anduras.de>");

MODULE_DESCRIPTION("Driver for SMsC 37B787 watchdog component (Version " VERSION ")");

MODULE_LICENSE("GPL");

MODULE_ALIAS_MISCDEV(WATCHDOG_MINOR);

#ifdef SMSC_SUPPORT_MINUTES

module_param(unit, int, 0);

MODULE_PARM_DESC(unit, "set unit to use, 0=seconds or 1=minutes, default is 0");

#endif

module_param(timeout, int, 0);

MODULE_PARM_DESC(timeout, "range is 1-255 units, default is 60");

module_param(nowayout, int, 0);

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