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/*

 *      National Semiconductor PC87307/PC97307 (ala SC1200) WDT driver

 *      (c) Copyright 2002 Zwane Mwaikambo <zwane@commfireservices.com>,

 *                      All Rights Reserved.

 *      Based on wdt.c and wdt977.c by Alan Cox and Woody Suwalski respectively.

 *

 *      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 author(s) of this software shall not be held liable for damages

 *      of any nature resulting due to the use of this software. This

 *      software is provided AS-IS with no warranties.

 *

 *      Changelog:

 *      20020220 Zwane Mwaikambo        Code based on datasheet, no hardware.

 *      20020221 Zwane Mwaikambo        Cleanups as suggested by Jeff Garzik and Alan Cox.

 *      20020222 Zwane Mwaikambo        Added probing.

 *      20020225 Zwane Mwaikambo        Added ISAPNP support.

 *      20020412 Rob Radez              Broke out start/stop functions

 *               <rob@osinvestor.com>   Return proper status instead of temperature warning

 *                                      Add WDIOC_GETBOOTSTATUS and WDIOC_SETOPTIONS ioctls

 *                                      Fix CONFIG_WATCHDOG_NOWAYOUT

 *      20020530 Joel Becker            Add Matt Domsch's nowayout module option

 *      20030116 Adam Belay             Updated to the latest pnp code

 *

 */

#include <linux/module.h>

#include <linux/moduleparam.h>

#include <linux/miscdevice.h>

#include <linux/watchdog.h>

#include <linux/ioport.h>

#include <linux/spinlock.h>

#include <linux/notifier.h>

#include <linux/reboot.h>

#include <linux/init.h>

#include <linux/pnp.h>

#include <linux/fs.h>

#include <asm/semaphore.h>

#include <asm/io.h>

#include <asm/uaccess.h>

#define SC1200_MODULE_VER       "build 20020303"

#define SC1200_MODULE_NAME      "sc1200wdt"

#define PFX                     SC1200_MODULE_NAME ": "

#define MAX_TIMEOUT     255     /* 255 minutes */

#define PMIR            (io)    /* Power Management Index Register */

#define PMDR            (io+1)  /* Power Management Data Register */

/* Data Register indexes */

#define FER1            0x00    /* Function enable register 1 */

#define FER2            0x01    /* Function enable register 2 */

#define PMC1            0x02    /* Power Management Ctrl 1 */

#define PMC2            0x03    /* Power Management Ctrl 2 */

#define PMC3            0x04    /* Power Management Ctrl 3 */

#define WDTO            0x05    /* Watchdog timeout register */

#define WDCF            0x06    /* Watchdog config register */

#define WDST            0x07    /* Watchdog status register */

/* WDCF bitfields - which devices assert WDO */

#define KBC_IRQ         0x01    /* Keyboard Controller */

#define MSE_IRQ         0x02    /* Mouse */

#define UART1_IRQ       0x03    /* Serial0 */

#define UART2_IRQ       0x04    /* Serial1 */

/* 5 -7 are reserved */

static char banner[] __initdata = KERN_INFO PFX SC1200_MODULE_VER;

static int timeout = 1;

static int io = -1;

static int io_len = 2;          /* for non plug and play */

static struct semaphore open_sem;

static char expect_close;

static DEFINE_SPINLOCK(sc1200wdt_lock); /* io port access serialisation */

#if defined CONFIG_PNP

static int isapnp = 1;

static struct pnp_dev *wdt_dev;

module_param(isapnp, int, 0);

MODULE_PARM_DESC(isapnp, "When set to 0 driver ISA PnP support will be disabled");

#endif

module_param(io, int, 0);

MODULE_PARM_DESC(io, "io port");

module_param(timeout, int, 0);

MODULE_PARM_DESC(timeout, "range is 0-255 minutes, default is 1");

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) ")");

/* Read from Data Register */

static inline void sc1200wdt_read_data(unsigned char index, unsigned char *data)

{

        spin_lock(&sc1200wdt_lock);

        outb_p(index, PMIR);

        *data = inb(PMDR);

        spin_unlock(&sc1200wdt_lock);

}

/* Write to Data Register */

static inline void sc1200wdt_write_data(unsigned char index, unsigned char data)

{

        spin_lock(&sc1200wdt_lock);

        outb_p(index, PMIR);

        outb(data, PMDR);

        spin_unlock(&sc1200wdt_lock);

}

static void sc1200wdt_start(void)

{

        unsigned char reg;

        sc1200wdt_read_data(WDCF, &reg);

        /* assert WDO when any of the following interrupts are triggered too */

        reg |= (KBC_IRQ | MSE_IRQ | UART1_IRQ | UART2_IRQ);

        sc1200wdt_write_data(WDCF, reg);

        /* set the timeout and get the ball rolling */

        sc1200wdt_write_data(WDTO, timeout);

}

static void sc1200wdt_stop(void)

{

        sc1200wdt_write_data(WDTO, 0);

}

/* This returns the status of the WDO signal, inactive high. */

static inline int sc1200wdt_status(void)

{

        unsigned char ret;

        sc1200wdt_read_data(WDST, &ret);

        /* If the bit is inactive, the watchdog is enabled, so return

         * KEEPALIVEPING which is a bit of a kludge because there's nothing

         * else for enabled/disabled status

         */

        return (ret & 0x01) ? 0 : WDIOF_KEEPALIVEPING;   /* bits 1 - 7 are undefined */

}

static int sc1200wdt_open(struct inode *inode, struct file *file)

{

        /* allow one at a time */

        if (down_trylock(&open_sem))

                return -EBUSY;

        if (timeout > MAX_TIMEOUT)

                timeout = MAX_TIMEOUT;

        sc1200wdt_start();

        printk(KERN_INFO PFX "Watchdog enabled, timeout = %d min(s)", timeout);

        return nonseekable_open(inode, file);

}

static int sc1200wdt_ioctl(struct inode *inode, struct file *file, unsigned int cmd, unsigned long arg)

{

        int new_timeout;

        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 = "PC87307/PC97307",

        };

        switch (cmd) {

                default:

                        return -ENOTTY;

                case WDIOC_GETSUPPORT:

                        if (copy_to_user(argp, &ident, sizeof ident))

                                return -EFAULT;

                        return 0;

                case WDIOC_GETSTATUS:

                        return put_user(sc1200wdt_status(), p);

                case WDIOC_GETBOOTSTATUS:

                        return put_user(0, p);

                case WDIOC_KEEPALIVE:

                        sc1200wdt_write_data(WDTO, timeout);

                        return 0;

                case WDIOC_SETTIMEOUT:

                        if (get_user(new_timeout, p))

                                return -EFAULT;

                        /* the API states this is given in secs */

                        new_timeout /= 60;

                        if (new_timeout < 0 || new_timeout > MAX_TIMEOUT)

                                return -EINVAL;

                        timeout = new_timeout;

                        sc1200wdt_write_data(WDTO, timeout);

                        /* fall through and return the new timeout */

                case WDIOC_GETTIMEOUT:

                        return put_user(timeout * 60, p);

                case WDIOC_SETOPTIONS:

                {

                        int options, retval = -EINVAL;

                        if (get_user(options, p))

                                return -EFAULT;

                        if (options & WDIOS_DISABLECARD) {

                                sc1200wdt_stop();

                                retval = 0;

                        }

                        if (options & WDIOS_ENABLECARD) {

                                sc1200wdt_start();

                                retval = 0;

                        }

                        return retval;

                }

        }

}

static int sc1200wdt_release(struct inode *inode, struct file *file)

{

        if (expect_close == 42) {

                sc1200wdt_stop();

                printk(KERN_INFO PFX "Watchdog disabled\n");

        } else {

                sc1200wdt_write_data(WDTO, timeout);

                printk(KERN_CRIT PFX "Unexpected close!, timeout = %d min(s)\n", timeout);

        }

        up(&open_sem);

        expect_close = 0;

        return 0;

}

static ssize_t sc1200wdt_write(struct file *file, const char __user *data, size_t len, loff_t *ppos)

{

        if (len) {

                if (!nowayout) {

                        size_t i;

                        expect_close = 0;

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

                                char c;

                                if (get_user(c, data+i))

                                        return -EFAULT;

                                if (c == 'V')

                                        expect_close = 42;

                        }

                }

                sc1200wdt_write_data(WDTO, timeout);

                return len;

        }

        return 0;

}

static int sc1200wdt_notify_sys(struct notifier_block *this, unsigned long code, void *unused)

{

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

                sc1200wdt_stop();

        return NOTIFY_DONE;

}

static struct notifier_block sc1200wdt_notifier =

{

        .notifier_call =        sc1200wdt_notify_sys,

};

static const struct file_operations sc1200wdt_fops =

{

        .owner          = THIS_MODULE,

        .llseek         = no_llseek,

        .write          = sc1200wdt_write,

        .ioctl          = sc1200wdt_ioctl,

        .open           = sc1200wdt_open,

        .release        = sc1200wdt_release,

};

static struct miscdevice sc1200wdt_miscdev =

{

        .minor          = WATCHDOG_MINOR,

        .name           = "watchdog",

        .fops           = &sc1200wdt_fops,

};

static int __init sc1200wdt_probe(void)

{

        /* The probe works by reading the PMC3 register's default value of 0x0e

         * there is one caveat, if the device disables the parallel port or any

         * of the UARTs we won't be able to detect it.

         * Nb. This could be done with accuracy by reading the SID registers, but

         * we don't have access to those io regions.

         */

        unsigned char reg;

        sc1200wdt_read_data(PMC3, &reg);

        reg &= 0x0f;                            /* we don't want the UART busy bits */

        return (reg == 0x0e) ? 0 : -ENODEV;

}

#if defined CONFIG_PNP

static struct pnp_device_id scl200wdt_pnp_devices[] = {

        /* National Semiconductor PC87307/PC97307 watchdog component */

        {.id = "NSC0800", .driver_data = 0},

        {.id = ""},

};

static int scl200wdt_pnp_probe(struct pnp_dev * dev, const struct pnp_device_id *dev_id)

{

        /* this driver only supports one card at a time */

        if (wdt_dev || !isapnp)

                return -EBUSY;

        wdt_dev = dev;

        io = pnp_port_start(wdt_dev, 0);

        io_len = pnp_port_len(wdt_dev, 0);

        if (!request_region(io, io_len, SC1200_MODULE_NAME)) {

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

                return -EBUSY;

        }

        printk(KERN_INFO "scl200wdt: PnP device found at io port %#x/%d\n", io, io_len);

        return 0;

}

static void scl200wdt_pnp_remove(struct pnp_dev * dev)

{

        if (wdt_dev){

                release_region(io, io_len);

                wdt_dev = NULL;

        }

}

static struct pnp_driver scl200wdt_pnp_driver = {

        .name           = "scl200wdt",

        .id_table       = scl200wdt_pnp_devices,

        .probe          = scl200wdt_pnp_probe,

        .remove         = scl200wdt_pnp_remove,

};

#endif /* CONFIG_PNP */

static int __init sc1200wdt_init(void)

{

        int ret;

        printk("%s\n", banner);

        sema_init(&open_sem, 1);

#if defined CONFIG_PNP

        if (isapnp) {

                ret = pnp_register_driver(&scl200wdt_pnp_driver);

                if (ret)

                        goto out_clean;

        }

#endif

        if (io == -1) {

                printk(KERN_ERR PFX "io parameter must be specified\n");

                ret = -EINVAL;

                goto out_pnp;

        }

#if defined CONFIG_PNP

        /* now that the user has specified an IO port and we haven't detected

         * any devices, disable pnp support */

        isapnp = 0;

        pnp_unregister_driver(&scl200wdt_pnp_driver);

#endif

        if (!request_region(io, io_len, SC1200_MODULE_NAME)) {

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

                ret = -EBUSY;

                goto out_pnp;

        }

        ret = sc1200wdt_probe();

        if (ret)

                goto out_io;

        ret = register_reboot_notifier(&sc1200wdt_notifier);

        if (ret) {

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

                goto out_io;

        }

        ret = misc_register(&sc1200wdt_miscdev);

        if (ret) {

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

                goto out_rbt;

        }

        /* ret = 0 */

out_clean:

        return ret;

out_rbt:

        unregister_reboot_notifier(&sc1200wdt_notifier);

out_io:

        release_region(io, io_len);

out_pnp:

#if defined CONFIG_PNP

        if (isapnp)

                pnp_unregister_driver(&scl200wdt_pnp_driver);

#endif

        goto out_clean;

}

static void __exit sc1200wdt_exit(void)

{

        misc_deregister(&sc1200wdt_miscdev);

        unregister_reboot_notifier(&sc1200wdt_notifier);

#if defined CONFIG_PNP

        if(isapnp)

                pnp_unregister_driver(&scl200wdt_pnp_driver);

        else

#endif

        release_region(io, io_len);

}

module_init(sc1200wdt_init);

module_exit(sc1200wdt_exit);

MODULE_AUTHOR("Zwane Mwaikambo <zwane@commfireservices.com>");

MODULE_DESCRIPTION("Driver for National Semiconductor PC87307/PC97307 watchdog component");

MODULE_LICENSE("GPL");

MODULE_ALIAS_MISCDEV(WATCHDOG_MINOR);