sc1200wdt.c

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/*
 *  National Semiconductor PC87307/PC97307 (ala SC1200) WDT driver
 *  (c) Copyright 2002 Zwane Mwaikambo <[email protected]>,
 *          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
 *       <[email protected]>   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
 *
 */

#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt

#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 <linux/semaphore.h>
#include <linux/io.h>
#include <linux/uaccess.h>

#define SC1200_MODULE_VER   "build 20020303"
#define SC1200_MODULE_NAME  "sc1200wdt"

#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 int timeout = 1;
static int io = -1;
static int io_len = 2;      /* for non plug and play */
static unsigned long open_flag;
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 bool nowayout = WATCHDOG_NOWAYOUT;
module_param(nowayout, bool, 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)
{
    outb_p(index, PMIR);
    *data = inb(PMDR);
}

static void sc1200wdt_read_data(unsigned char index, unsigned char *data)
{
    spin_lock(&sc1200wdt_lock);
    __sc1200wdt_read_data(index, data);
    spin_unlock(&sc1200wdt_lock);
}

/* Write to Data Register */
static inline void __sc1200wdt_write_data(unsigned char index,
                        unsigned char data)
{
    outb_p(index, PMIR);
    outb(data, PMDR);
}

static inline void sc1200wdt_write_data(unsigned char index,
                        unsigned char data)
{
    spin_lock(&sc1200wdt_lock);
    __sc1200wdt_write_data(index, data);
    spin_unlock(&sc1200wdt_lock);
}


static void sc1200wdt_start(void)
{
    unsigned char reg;
    spin_lock(&sc1200wdt_lock);

    __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);

    spin_unlock(&sc1200wdt_lock);
}

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;
}

static int sc1200wdt_open(struct inode *inode, struct file *file)
{
    /* allow one at a time */
    if (test_and_set_bit(0, &open_flag))
        return -EBUSY;

    if (timeout > MAX_TIMEOUT)
        timeout = MAX_TIMEOUT;

    sc1200wdt_start();
    pr_info("Watchdog enabled, timeout = %d min(s)", timeout);

    return nonseekable_open(inode, file);
}


static long sc1200wdt_ioctl(struct file *file, unsigned int cmd,
                        unsigned long arg)
{
    int new_timeout;
    void __user *argp = (void __user *)arg;
    int __user *p = argp;
    static const struct watchdog_info ident = {
        .options = WDIOF_KEEPALIVEPING | WDIOF_SETTIMEOUT |
                            WDIOF_MAGICCLOSE,
        .firmware_version = 0,
        .identity = "PC87307/PC97307",
    };

    switch (cmd) {
    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_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;
    }
    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);

    default:
        return -ENOTTY;
    }
}


static int sc1200wdt_release(struct inode *inode, struct file *file)
{
    if (expect_close == 42) {
        sc1200wdt_stop();
        pr_info("Watchdog disabled\n");
    } else {
        sc1200wdt_write_data(WDTO, timeout);
        pr_crit("Unexpected close!, timeout = %d min(s)\n", timeout);
    }
    clear_bit(0, &open_flag);
    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,
    .unlocked_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)) {
        pr_err("Unable to register IO port %#x\n", io);
        return -EBUSY;
    }

    pr_info("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;

    pr_info("%s\n", SC1200_MODULE_VER);

#if defined CONFIG_PNP
    if (isapnp) {
        ret = pnp_register_driver(&scl200wdt_pnp_driver);
        if (ret)
            goto out_clean;
    }
#endif

    if (io == -1) {
        pr_err("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)) {
        pr_err("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) {
        pr_err("Unable to register reboot notifier err = %d\n", ret);
        goto out_io;
    }

    ret = misc_register(&sc1200wdt_miscdev);
    if (ret) {
        pr_err("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 <[email protected]>");
MODULE_DESCRIPTION(
    "Driver for National Semiconductor PC87307/PC97307 watchdog component");
MODULE_LICENSE("GPL");
MODULE_ALIAS_MISCDEV(WATCHDOG_MINOR);