alim7101_wdt.c

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/*
 *  ALi M7101 PMU Computer Watchdog Timer driver
 *
 *  Based on w83877f_wdt.c by Scott Jennings <[email protected]>
 *  and the Cobalt kernel WDT timer driver by Tim Hockin
 *                                        <[email protected]>
 *
 *  (c)2002 Steve Hill <[email protected]>
 *
 *  This WDT driver is different from most other Linux WDT
 *  drivers in that the driver will ping the watchdog by itself,
 *  because this particular WDT has a very short timeout (1.6
 *  seconds) and it would be insane to count on any userspace
 *  daemon always getting scheduled within that time frame.
 *
 *  Additions:
 *   Aug 23, 2004 - Added use_gpio module parameter for use on revision a1d PMUs
 *                  found on very old cobalt hardware.
 *                  -- Mike Waychison <[email protected]>
 */

#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt

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


#define WDT_ENABLE 0x9C
#define WDT_DISABLE 0x8C

#define ALI_7101_WDT    0x92
#define ALI_7101_GPIO   0x7D
#define ALI_7101_GPIO_O 0x7E
#define ALI_WDT_ARM     0x01

/*
 * We're going to use a 1 second timeout.
 * If we reset the watchdog every ~250ms we should be safe.  */

#define WDT_INTERVAL (HZ/4+1)

/*
 * We must not require too good response from the userspace daemon.
 * Here we require the userspace daemon to send us a heartbeat
 * char to /dev/watchdog every 30 seconds.
 */

#define WATCHDOG_TIMEOUT 30            /* 30 sec default timeout */
/* in seconds, will be multiplied by HZ to get seconds to wait for a ping */
static int timeout = WATCHDOG_TIMEOUT;
module_param(timeout, int, 0);
MODULE_PARM_DESC(timeout,
        "Watchdog timeout in seconds. (1<=timeout<=3600, default="
                __MODULE_STRING(WATCHDOG_TIMEOUT) ")");

static int use_gpio; /* Use the pic (for a1d revision alim7101) */
module_param(use_gpio, int, 0);
MODULE_PARM_DESC(use_gpio,
        "Use the gpio watchdog (required by old cobalt boards).");

static void wdt_timer_ping(unsigned long);
static DEFINE_TIMER(timer, wdt_timer_ping, 0, 1);
static unsigned long next_heartbeat;
static unsigned long wdt_is_open;
static char wdt_expect_close;
static struct pci_dev *alim7101_pmu;

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) ")");

/*
 *  Whack the dog
 */

static void wdt_timer_ping(unsigned long data)
{
    /* If we got a heartbeat pulse within the WDT_US_INTERVAL
     * we agree to ping the WDT
     */
    char tmp;

    if (time_before(jiffies, next_heartbeat)) {
        /* Ping the WDT (this is actually a disarm/arm sequence) */
        pci_read_config_byte(alim7101_pmu, 0x92, &tmp);
        pci_write_config_byte(alim7101_pmu,
                    ALI_7101_WDT, (tmp & ~ALI_WDT_ARM));
        pci_write_config_byte(alim7101_pmu,
                    ALI_7101_WDT, (tmp | ALI_WDT_ARM));
        if (use_gpio) {
            pci_read_config_byte(alim7101_pmu,
                    ALI_7101_GPIO_O, &tmp);
            pci_write_config_byte(alim7101_pmu,
                    ALI_7101_GPIO_O, tmp | 0x20);
            pci_write_config_byte(alim7101_pmu,
                    ALI_7101_GPIO_O, tmp & ~0x20);
        }
    } else {
        pr_warn("Heartbeat lost! Will not ping the watchdog\n");
    }
    /* Re-set the timer interval */
    mod_timer(&timer, jiffies + WDT_INTERVAL);
}

/*
 * Utility routines
 */

static void wdt_change(int writeval)
{
    char tmp;

    pci_read_config_byte(alim7101_pmu, ALI_7101_WDT, &tmp);
    if (writeval == WDT_ENABLE) {
        pci_write_config_byte(alim7101_pmu,
                    ALI_7101_WDT, (tmp | ALI_WDT_ARM));
        if (use_gpio) {
            pci_read_config_byte(alim7101_pmu,
                    ALI_7101_GPIO_O, &tmp);
            pci_write_config_byte(alim7101_pmu,
                    ALI_7101_GPIO_O, tmp & ~0x20);
        }

    } else {
        pci_write_config_byte(alim7101_pmu,
                    ALI_7101_WDT, (tmp & ~ALI_WDT_ARM));
        if (use_gpio) {
            pci_read_config_byte(alim7101_pmu,
                    ALI_7101_GPIO_O, &tmp);
            pci_write_config_byte(alim7101_pmu,
                    ALI_7101_GPIO_O, tmp | 0x20);
        }
    }
}

static void wdt_startup(void)
{
    next_heartbeat = jiffies + (timeout * HZ);

    /* We must enable before we kick off the timer in case the timer
       occurs as we ping it */

    wdt_change(WDT_ENABLE);

    /* Start the timer */
    mod_timer(&timer, jiffies + WDT_INTERVAL);

    pr_info("Watchdog timer is now enabled\n");
}

static void wdt_turnoff(void)
{
    /* Stop the timer */
    del_timer_sync(&timer);
    wdt_change(WDT_DISABLE);
    pr_info("Watchdog timer is now disabled...\n");
}

static void wdt_keepalive(void)
{
    /* user land ping */
    next_heartbeat = jiffies + (timeout * HZ);
}

/*
 * /dev/watchdog handling
 */

static ssize_t fop_write(struct file *file, const char __user *buf,
                        size_t count, loff_t *ppos)
{
    /* See if we got the magic character 'V' and reload the timer */
    if (count) {
        if (!nowayout) {
            size_t ofs;

            /* note: just in case someone wrote the magic character
             * five months ago... */
            wdt_expect_close = 0;

            /* now scan */
            for (ofs = 0; ofs != count; ofs++) {
                char c;
                if (get_user(c, buf + ofs))
                    return -EFAULT;
                if (c == 'V')
                    wdt_expect_close = 42;
            }
        }
        /* someone wrote to us, we should restart timer */
        wdt_keepalive();
    }
    return count;
}

static int fop_open(struct inode *inode, struct file *file)
{
    /* Just in case we're already talking to someone... */
    if (test_and_set_bit(0, &wdt_is_open))
        return -EBUSY;
    /* Good, fire up the show */
    wdt_startup();
    return nonseekable_open(inode, file);
}

static int fop_close(struct inode *inode, struct file *file)
{
    if (wdt_expect_close == 42)
        wdt_turnoff();
    else {
        /* wim: shouldn't there be a: del_timer(&timer); */
        pr_crit("device file closed unexpectedly. Will not stop the WDT!\n");
    }
    clear_bit(0, &wdt_is_open);
    wdt_expect_close = 0;
    return 0;
}

static long fop_ioctl(struct file *file, unsigned int cmd, unsigned long arg)
{
    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 = 1,
        .identity = "ALiM7101",
    };

    switch (cmd) {
    case WDIOC_GETSUPPORT:
        return copy_to_user(argp, &ident, sizeof(ident)) ? -EFAULT : 0;
    case WDIOC_GETSTATUS:
    case WDIOC_GETBOOTSTATUS:
        return put_user(0, p);
    case WDIOC_SETOPTIONS:
    {
        int new_options, retval = -EINVAL;

        if (get_user(new_options, p))
            return -EFAULT;
        if (new_options & WDIOS_DISABLECARD) {
            wdt_turnoff();
            retval = 0;
        }
        if (new_options & WDIOS_ENABLECARD) {
            wdt_startup();
            retval = 0;
        }
        return retval;
    }
    case WDIOC_KEEPALIVE:
        wdt_keepalive();
        return 0;
    case WDIOC_SETTIMEOUT:
    {
        int new_timeout;

        if (get_user(new_timeout, p))
            return -EFAULT;
        /* arbitrary upper limit */
        if (new_timeout < 1 || new_timeout > 3600)
            return -EINVAL;
        timeout = new_timeout;
        wdt_keepalive();
        /* Fall through */
    }
    case WDIOC_GETTIMEOUT:
        return put_user(timeout, p);
    default:
        return -ENOTTY;
    }
}

static const struct file_operations wdt_fops = {
    .owner      =   THIS_MODULE,
    .llseek     =   no_llseek,
    .write      =   fop_write,
    .open       =   fop_open,
    .release    =   fop_close,
    .unlocked_ioctl =   fop_ioctl,
};

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

/*
 *  Notifier for system down
 */

static int wdt_notify_sys(struct notifier_block *this,
                    unsigned long code, void *unused)
{
    if (code == SYS_DOWN || code == SYS_HALT)
        wdt_turnoff();

    if (code == SYS_RESTART) {
        /*
         * Cobalt devices have no way of rebooting themselves other
         * than getting the watchdog to pull reset, so we restart the
         * watchdog on reboot with no heartbeat
         */
        wdt_change(WDT_ENABLE);
        pr_info("Watchdog timer is now enabled with no heartbeat - should reboot in ~1 second\n");
    }
    return NOTIFY_DONE;
}

/*
 *  The WDT needs to learn about soft shutdowns in order to
 *  turn the timebomb registers off.
 */

static struct notifier_block wdt_notifier = {
    .notifier_call = wdt_notify_sys,
};

static void __exit alim7101_wdt_unload(void)
{
    wdt_turnoff();
    /* Deregister */
    misc_deregister(&wdt_miscdev);
    unregister_reboot_notifier(&wdt_notifier);
    pci_dev_put(alim7101_pmu);
}

static int __init alim7101_wdt_init(void)
{
    int rc = -EBUSY;
    struct pci_dev *ali1543_south;
    char tmp;

    pr_info("Steve Hill <[email protected]>\n");
    alim7101_pmu = pci_get_device(PCI_VENDOR_ID_AL, PCI_DEVICE_ID_AL_M7101,
        NULL);
    if (!alim7101_pmu) {
        pr_info("ALi M7101 PMU not present - WDT not set\n");
        return -EBUSY;
    }

    /* Set the WDT in the PMU to 1 second */
    pci_write_config_byte(alim7101_pmu, ALI_7101_WDT, 0x02);

    ali1543_south = pci_get_device(PCI_VENDOR_ID_AL, PCI_DEVICE_ID_AL_M1533,
        NULL);
    if (!ali1543_south) {
        pr_info("ALi 1543 South-Bridge not present - WDT not set\n");
        goto err_out;
    }
    pci_read_config_byte(ali1543_south, 0x5e, &tmp);
    pci_dev_put(ali1543_south);
    if ((tmp & 0x1e) == 0x00) {
        if (!use_gpio) {
            pr_info("Detected old alim7101 revision 'a1d'.  If this is a cobalt board, set the 'use_gpio' module parameter.\n");
            goto err_out;
        }
        nowayout = 1;
    } else if ((tmp & 0x1e) != 0x12 && (tmp & 0x1e) != 0x00) {
        pr_info("ALi 1543 South-Bridge does not have the correct revision number (???1001?) - WDT not set\n");
        goto err_out;
    }

    if (timeout < 1 || timeout > 3600) {
        /* arbitrary upper limit */
        timeout = WATCHDOG_TIMEOUT;
        pr_info("timeout value must be 1 <= x <= 3600, using %d\n",
            timeout);
    }

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

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

    if (nowayout)
        __module_get(THIS_MODULE);

    pr_info("WDT driver for ALi M7101 initialised. timeout=%d sec (nowayout=%d)\n",
        timeout, nowayout);
    return 0;

err_out_reboot:
    unregister_reboot_notifier(&wdt_notifier);
err_out:
    pci_dev_put(alim7101_pmu);
    return rc;
}

module_init(alim7101_wdt_init);
module_exit(alim7101_wdt_unload);

static DEFINE_PCI_DEVICE_TABLE(alim7101_pci_tbl) __used = {
    { PCI_DEVICE(PCI_VENDOR_ID_AL, PCI_DEVICE_ID_AL_M1533) },
    { PCI_DEVICE(PCI_VENDOR_ID_AL, PCI_DEVICE_ID_AL_M7101) },
    { }
};

MODULE_DEVICE_TABLE(pci, alim7101_pci_tbl);

MODULE_AUTHOR("Steve Hill");
MODULE_DESCRIPTION("ALi M7101 PMU Computer Watchdog Timer driver");
MODULE_LICENSE("GPL");
MODULE_ALIAS_MISCDEV(WATCHDOG_MINOR);