pc87413_wdt.c

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/*
 *      NS pc87413-wdt Watchdog Timer driver for Linux 2.6.x.x
 *
 *      This code is based on wdt.c with original copyright.
 *
 *      (C) Copyright 2006 Sven Anders, <[email protected]>
 *                     and Marcus Junker, <[email protected]>
 *
 *      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.
 *
 *      Neither Sven Anders, Marcus Junker nor ANDURAS AG
 *      admit liability nor provide warranty for any of this software.
 *      This material is provided "AS-IS" and at no charge.
 *
 *      Release 1.1
 */

#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt

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


/* #define DEBUG 1 */

#define DEFAULT_TIMEOUT     1       /* 1 minute */
#define MAX_TIMEOUT         255

#define VERSION             "1.1"
#define MODNAME             "pc87413 WDT"
#define DPFX                MODNAME " - DEBUG: "

#define WDT_INDEX_IO_PORT   (io+0)  /* I/O port base (index register) */
#define WDT_DATA_IO_PORT    (WDT_INDEX_IO_PORT+1)
#define SWC_LDN             0x04
#define SIOCFG2             0x22    /* Serial IO register */
#define WDCTL               0x10    /* Watchdog-Timer-Control-Register */
#define WDTO                0x11    /* Watchdog timeout register */
#define WDCFG               0x12    /* Watchdog config register */

#define IO_DEFAULT  0x2E        /* Address used on Portwell Boards */

static int io = IO_DEFAULT;
static int swc_base_addr = -1;

static int timeout = DEFAULT_TIMEOUT;   /* timeout value */
static unsigned long timer_enabled; /* is the timer enabled? */

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

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

static bool nowayout = WATCHDOG_NOWAYOUT;

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

/* Select pins for Watchdog output */

static inline void pc87413_select_wdt_out(void)
{
    unsigned int cr_data = 0;

    /* Step 1: Select multiple pin,pin55,as WDT output */

    outb_p(SIOCFG2, WDT_INDEX_IO_PORT);

    cr_data = inb(WDT_DATA_IO_PORT);

    cr_data |= 0x80; /* Set Bit7 to 1*/
    outb_p(SIOCFG2, WDT_INDEX_IO_PORT);

    outb_p(cr_data, WDT_DATA_IO_PORT);

#ifdef DEBUG
    pr_info(DPFX
        "Select multiple pin,pin55,as WDT output: Bit7 to 1: %d\n",
                                cr_data);
#endif
}

/* Enable SWC functions */

static inline void pc87413_enable_swc(void)
{
    unsigned int cr_data = 0;

    /* Step 2: Enable SWC functions */

    outb_p(0x07, WDT_INDEX_IO_PORT);    /* Point SWC_LDN (LDN=4) */
    outb_p(SWC_LDN, WDT_DATA_IO_PORT);

    outb_p(0x30, WDT_INDEX_IO_PORT);    /* Read Index 0x30 First */
    cr_data = inb(WDT_DATA_IO_PORT);
    cr_data |= 0x01;            /* Set Bit0 to 1 */
    outb_p(0x30, WDT_INDEX_IO_PORT);
    outb_p(cr_data, WDT_DATA_IO_PORT);  /* Index0x30_bit0P1 */

#ifdef DEBUG
    pr_info(DPFX "pc87413 - Enable SWC functions\n");
#endif
}

/* Read SWC I/O base address */

static void pc87413_get_swc_base_addr(void)
{
    unsigned char addr_l, addr_h = 0;

    /* Step 3: Read SWC I/O Base Address */

    outb_p(0x60, WDT_INDEX_IO_PORT);    /* Read Index 0x60 */
    addr_h = inb(WDT_DATA_IO_PORT);

    outb_p(0x61, WDT_INDEX_IO_PORT);    /* Read Index 0x61 */

    addr_l = inb(WDT_DATA_IO_PORT);

    swc_base_addr = (addr_h << 8) + addr_l;
#ifdef DEBUG
    pr_info(DPFX
        "Read SWC I/O Base Address: low %d, high %d, res %d\n",
                        addr_l, addr_h, swc_base_addr);
#endif
}

/* Select Bank 3 of SWC */

static inline void pc87413_swc_bank3(void)
{
    /* Step 4: Select Bank3 of SWC */
    outb_p(inb(swc_base_addr + 0x0f) | 0x03, swc_base_addr + 0x0f);
#ifdef DEBUG
    pr_info(DPFX "Select Bank3 of SWC\n");
#endif
}

/* Set watchdog timeout to x minutes */

static inline void pc87413_programm_wdto(char pc87413_time)
{
    /* Step 5: Programm WDTO, Twd. */
    outb_p(pc87413_time, swc_base_addr + WDTO);
#ifdef DEBUG
    pr_info(DPFX "Set WDTO to %d minutes\n", pc87413_time);
#endif
}

/* Enable WDEN */

static inline void pc87413_enable_wden(void)
{
    /* Step 6: Enable WDEN */
    outb_p(inb(swc_base_addr + WDCTL) | 0x01, swc_base_addr + WDCTL);
#ifdef DEBUG
    pr_info(DPFX "Enable WDEN\n");
#endif
}

/* Enable SW_WD_TREN */
static inline void pc87413_enable_sw_wd_tren(void)
{
    /* Enable SW_WD_TREN */
    outb_p(inb(swc_base_addr + WDCFG) | 0x80, swc_base_addr + WDCFG);
#ifdef DEBUG
    pr_info(DPFX "Enable SW_WD_TREN\n");
#endif
}

/* Disable SW_WD_TREN */

static inline void pc87413_disable_sw_wd_tren(void)
{
    /* Disable SW_WD_TREN */
    outb_p(inb(swc_base_addr + WDCFG) & 0x7f, swc_base_addr + WDCFG);
#ifdef DEBUG
    pr_info(DPFX "pc87413 - Disable SW_WD_TREN\n");
#endif
}

/* Enable SW_WD_TRG */

static inline void pc87413_enable_sw_wd_trg(void)
{
    /* Enable SW_WD_TRG */
    outb_p(inb(swc_base_addr + WDCTL) | 0x80, swc_base_addr + WDCTL);
#ifdef DEBUG
    pr_info(DPFX "pc87413 - Enable SW_WD_TRG\n");
#endif
}

/* Disable SW_WD_TRG */

static inline void pc87413_disable_sw_wd_trg(void)
{
    /* Disable SW_WD_TRG */
    outb_p(inb(swc_base_addr + WDCTL) & 0x7f, swc_base_addr + WDCTL);
#ifdef DEBUG
    pr_info(DPFX "Disable SW_WD_TRG\n");
#endif
}

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

/* Enable the watchdog */

static void pc87413_enable(void)
{
    spin_lock(&io_lock);

    pc87413_swc_bank3();
    pc87413_programm_wdto(timeout);
    pc87413_enable_wden();
    pc87413_enable_sw_wd_tren();
    pc87413_enable_sw_wd_trg();

    spin_unlock(&io_lock);
}

/* Disable the watchdog */

static void pc87413_disable(void)
{
    spin_lock(&io_lock);

    pc87413_swc_bank3();
    pc87413_disable_sw_wd_tren();
    pc87413_disable_sw_wd_trg();
    pc87413_programm_wdto(0);

    spin_unlock(&io_lock);
}

/* Refresh the watchdog */

static void pc87413_refresh(void)
{
    spin_lock(&io_lock);

    pc87413_swc_bank3();
    pc87413_disable_sw_wd_tren();
    pc87413_disable_sw_wd_trg();
    pc87413_programm_wdto(timeout);
    pc87413_enable_wden();
    pc87413_enable_sw_wd_tren();
    pc87413_enable_sw_wd_trg();

    spin_unlock(&io_lock);
}

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

static int pc87413_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 */
    pc87413_refresh();

    pr_info("Watchdog enabled. Timeout set to %d minute(s).\n", timeout);

    return nonseekable_open(inode, file);
}

static int pc87413_release(struct inode *inode, struct file *file)
{
    /* Shut off the timer. */

    if (expect_close == 42) {
        pc87413_disable();
        pr_info("Watchdog disabled, sleeping again...\n");
    } else {
        pr_crit("Unexpected close, not stopping watchdog!\n");
        pc87413_refresh();
    }
    clear_bit(0, &timer_enabled);
    expect_close = 0;
    return 0;
}

static int pc87413_status(void)
{
      return 0; /* currently not supported */
}

static ssize_t pc87413_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 */
        pc87413_refresh();
    }
    return len;
}

static long pc87413_ioctl(struct file *file, unsigned int cmd,
                        unsigned long arg)
{
    int new_timeout;

    union {
        struct watchdog_info __user *ident;
        int __user *i;
    } uarg;

    static const struct watchdog_info ident = {
        .options          = WDIOF_KEEPALIVEPING |
                    WDIOF_SETTIMEOUT |
                    WDIOF_MAGICCLOSE,
        .firmware_version = 1,
        .identity         = "PC87413(HF/F) watchdog",
    };

    uarg.i = (int __user *)arg;

    switch (cmd) {
    case WDIOC_GETSUPPORT:
        return copy_to_user(uarg.ident, &ident,
                    sizeof(ident)) ? -EFAULT : 0;
    case WDIOC_GETSTATUS:
        return put_user(pc87413_status(), uarg.i);
    case WDIOC_GETBOOTSTATUS:
        return put_user(0, uarg.i);
    case WDIOC_SETOPTIONS:
    {
        int options, retval = -EINVAL;
        if (get_user(options, uarg.i))
            return -EFAULT;
        if (options & WDIOS_DISABLECARD) {
            pc87413_disable();
            retval = 0;
        }
        if (options & WDIOS_ENABLECARD) {
            pc87413_enable();
            retval = 0;
        }
        return retval;
    }
    case WDIOC_KEEPALIVE:
        pc87413_refresh();
#ifdef DEBUG
        pr_info(DPFX "keepalive\n");
#endif
        return 0;
    case WDIOC_SETTIMEOUT:
        if (get_user(new_timeout, uarg.i))
            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;
        pc87413_refresh();
        /* fall through and return the new timeout... */
    case WDIOC_GETTIMEOUT:
        new_timeout = timeout * 60;
        return put_user(new_timeout, uarg.i);
    default:
        return -ENOTTY;
    }
}

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

static int pc87413_notify_sys(struct notifier_block *this,
                  unsigned long code,
                  void *unused)
{
    if (code == SYS_DOWN || code == SYS_HALT)
        /* Turn the card off */
        pc87413_disable();
    return NOTIFY_DONE;
}

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

static const struct file_operations pc87413_fops = {
    .owner      = THIS_MODULE,
    .llseek     = no_llseek,
    .write      = pc87413_write,
    .unlocked_ioctl = pc87413_ioctl,
    .open       = pc87413_open,
    .release    = pc87413_release,
};

static struct notifier_block pc87413_notifier = {
    .notifier_call  = pc87413_notify_sys,
};

static struct miscdevice pc87413_miscdev = {
    .minor          = WATCHDOG_MINOR,
    .name           = "watchdog",
    .fops           = &pc87413_fops,
};

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

static int __init pc87413_init(void)
{
    int ret;

    pr_info("Version " VERSION " at io 0x%X\n",
                            WDT_INDEX_IO_PORT);

    if (!request_muxed_region(io, 2, MODNAME))
        return -EBUSY;

    ret = register_reboot_notifier(&pc87413_notifier);
    if (ret != 0) {
        pr_err("cannot register reboot notifier (err=%d)\n", ret);
    }

    ret = misc_register(&pc87413_miscdev);
    if (ret != 0) {
        pr_err("cannot register miscdev on minor=%d (err=%d)\n",
               WATCHDOG_MINOR, ret);
        goto reboot_unreg;
    }
    pr_info("initialized. timeout=%d min\n", timeout);

    pc87413_select_wdt_out();
    pc87413_enable_swc();
    pc87413_get_swc_base_addr();

    if (!request_region(swc_base_addr, 0x20, MODNAME)) {
        pr_err("cannot request SWC region at 0x%x\n", swc_base_addr);
        ret = -EBUSY;
        goto misc_unreg;
    }

    pc87413_enable();

    release_region(io, 2);
    return 0;

misc_unreg:
    misc_deregister(&pc87413_miscdev);
reboot_unreg:
    unregister_reboot_notifier(&pc87413_notifier);
    release_region(io, 2);
    return ret;
}

static void __exit pc87413_exit(void)
{
    /* Stop the timer before we leave */
    if (!nowayout) {
        pc87413_disable();
        pr_info("Watchdog disabled\n");
    }

    misc_deregister(&pc87413_miscdev);
    unregister_reboot_notifier(&pc87413_notifier);
    release_region(swc_base_addr, 0x20);

    pr_info("watchdog component driver removed\n");
}

module_init(pc87413_init);
module_exit(pc87413_exit);

MODULE_AUTHOR("Sven Anders <[email protected]>, "
        "Marcus Junker <[email protected]>,");
MODULE_DESCRIPTION("PC87413 WDT driver");
MODULE_LICENSE("GPL");

MODULE_ALIAS_MISCDEV(WATCHDOG_MINOR);

module_param(io, int, 0);
MODULE_PARM_DESC(io, MODNAME " I/O port (default: "
                    __MODULE_STRING(IO_DEFAULT) ").");

module_param(timeout, int, 0);
MODULE_PARM_DESC(timeout,
        "Watchdog timeout in minutes (default="
                __MODULE_STRING(DEFAULT_TIMEOUT) ").");

module_param(nowayout, bool, 0);
MODULE_PARM_DESC(nowayout,
        "Watchdog cannot be stopped once started (default="
                __MODULE_STRING(WATCHDOG_NOWAYOUT) ")");