wdrtas.c

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/*
 * FIXME: add wdrtas_get_status and wdrtas_get_boot_status as soon as
 * RTAS calls are available
 */

/*
 * RTAS watchdog driver
 *
 * (C) Copyright IBM Corp. 2005
 * device driver to exploit watchdog RTAS functions
 *
 * Authors : Utz Bacher <[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, or (at your option)
 * any later version.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program; if not, write to the Free Software
 * Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
 */

#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt

#include <linux/fs.h>
#include <linux/init.h>
#include <linux/kernel.h>
#include <linux/miscdevice.h>
#include <linux/module.h>
#include <linux/notifier.h>
#include <linux/reboot.h>
#include <linux/types.h>
#include <linux/watchdog.h>
#include <linux/uaccess.h>

#include <asm/rtas.h>

#define WDRTAS_MAGIC_CHAR       42
#define WDRTAS_SUPPORTED_MASK       (WDIOF_SETTIMEOUT | \
                     WDIOF_MAGICCLOSE)

MODULE_AUTHOR("Utz Bacher <[email protected]>");
MODULE_DESCRIPTION("RTAS watchdog driver");
MODULE_LICENSE("GPL");
MODULE_ALIAS_MISCDEV(WATCHDOG_MINOR);
MODULE_ALIAS_MISCDEV(TEMP_MINOR);

static bool wdrtas_nowayout = WATCHDOG_NOWAYOUT;
static atomic_t wdrtas_miscdev_open = ATOMIC_INIT(0);
static char wdrtas_expect_close;

static int wdrtas_interval;

#define WDRTAS_THERMAL_SENSOR       3
static int wdrtas_token_get_sensor_state;
#define WDRTAS_SURVEILLANCE_IND     9000
static int wdrtas_token_set_indicator;
#define WDRTAS_SP_SPI           28
static int wdrtas_token_get_sp;
static int wdrtas_token_event_scan;

#define WDRTAS_DEFAULT_INTERVAL     300

#define WDRTAS_LOGBUFFER_LEN        128
static char wdrtas_logbuffer[WDRTAS_LOGBUFFER_LEN];


/*** watchdog access functions */

static int wdrtas_set_interval(int interval)
{
    long result;
    static int print_msg = 10;

    /* rtas uses minutes */
    interval = (interval + 59) / 60;

    result = rtas_call(wdrtas_token_set_indicator, 3, 1, NULL,
               WDRTAS_SURVEILLANCE_IND, 0, interval);
    if (result < 0 && print_msg) {
        pr_err("setting the watchdog to %i timeout failed: %li\n",
               interval, result);
        print_msg--;
    }

    return result;
}

#define WDRTAS_SP_SPI_LEN 4

static int wdrtas_get_interval(int fallback_value)
{
    long result;
    char value[WDRTAS_SP_SPI_LEN];

    spin_lock(&rtas_data_buf_lock);
    memset(rtas_data_buf, 0, WDRTAS_SP_SPI_LEN);
    result = rtas_call(wdrtas_token_get_sp, 3, 1, NULL,
               WDRTAS_SP_SPI, __pa(rtas_data_buf),
               WDRTAS_SP_SPI_LEN);

    memcpy(value, rtas_data_buf, WDRTAS_SP_SPI_LEN);
    spin_unlock(&rtas_data_buf_lock);

    if (value[0] != 0 || value[1] != 2 || value[3] != 0 || result < 0) {
        pr_warn("could not get sp_spi watchdog timeout (%li). Continuing\n",
            result);
        return fallback_value;
    }

    /* rtas uses minutes */
    return ((int)value[2]) * 60;
}

static void wdrtas_timer_start(void)
{
    wdrtas_set_interval(wdrtas_interval);
}

static void wdrtas_timer_stop(void)
{
    wdrtas_set_interval(0);
}

static void wdrtas_log_scanned_event(void)
{
    int i;

    for (i = 0; i < WDRTAS_LOGBUFFER_LEN; i += 16)
        pr_info("dumping event (line %i/%i), data = "
            "%02x %02x %02x %02x  %02x %02x %02x %02x   "
            "%02x %02x %02x %02x  %02x %02x %02x %02x\n",
            (i / 16) + 1, (WDRTAS_LOGBUFFER_LEN / 16),
            wdrtas_logbuffer[i + 0], wdrtas_logbuffer[i + 1],
            wdrtas_logbuffer[i + 2], wdrtas_logbuffer[i + 3],
            wdrtas_logbuffer[i + 4], wdrtas_logbuffer[i + 5],
            wdrtas_logbuffer[i + 6], wdrtas_logbuffer[i + 7],
            wdrtas_logbuffer[i + 8], wdrtas_logbuffer[i + 9],
            wdrtas_logbuffer[i + 10], wdrtas_logbuffer[i + 11],
            wdrtas_logbuffer[i + 12], wdrtas_logbuffer[i + 13],
            wdrtas_logbuffer[i + 14], wdrtas_logbuffer[i + 15]);
}

static void wdrtas_timer_keepalive(void)
{
    long result;

    do {
        result = rtas_call(wdrtas_token_event_scan, 4, 1, NULL,
                   RTAS_EVENT_SCAN_ALL_EVENTS, 0,
                   (void *)__pa(wdrtas_logbuffer),
                   WDRTAS_LOGBUFFER_LEN);
        if (result < 0)
            pr_err("event-scan failed: %li\n", result);
        if (result == 0)
            wdrtas_log_scanned_event();
    } while (result == 0);
}

static int wdrtas_get_temperature(void)
{
    int result;
    int temperature = 0;

    result = rtas_get_sensor(WDRTAS_THERMAL_SENSOR, 0, &temperature);

    if (result < 0)
        pr_warn("reading the thermal sensor failed: %i\n", result);
    else
        temperature = ((temperature * 9) / 5) + 32; /* fahrenheit */

    return temperature;
}

static int wdrtas_get_status(void)
{
    return 0; /* TODO */
}

static int wdrtas_get_boot_status(void)
{
    return 0; /* TODO */
}

/*** watchdog API and operations stuff */

/* wdrtas_write - called when watchdog device is written to
 * @file: file structure
 * @buf: user buffer with data
 * @len: amount to data written
 * @ppos: position in file
 *
 * returns the number of successfully processed characters, which is always
 * the number of bytes passed to this function
 *
 * wdrtas_write processes all the data given to it and looks for the magic
 * character 'V'. This character allows the watchdog device to be closed
 * properly.
 */
static ssize_t wdrtas_write(struct file *file, const char __user *buf,
         size_t len, loff_t *ppos)
{
    int i;
    char c;

    if (!len)
        goto out;

    if (!wdrtas_nowayout) {
        wdrtas_expect_close = 0;
        /* look for 'V' */
        for (i = 0; i < len; i++) {
            if (get_user(c, buf + i))
                return -EFAULT;
            /* allow to close device */
            if (c == 'V')
                wdrtas_expect_close = WDRTAS_MAGIC_CHAR;
        }
    }

    wdrtas_timer_keepalive();

out:
    return len;
}

static long wdrtas_ioctl(struct file *file, unsigned int cmd,
                            unsigned long arg)
{
    int __user *argp = (void __user *)arg;
    int i;
    static const struct watchdog_info wdinfo = {
        .options = WDRTAS_SUPPORTED_MASK,
        .firmware_version = 0,
        .identity = "wdrtas",
    };

    switch (cmd) {
    case WDIOC_GETSUPPORT:
        if (copy_to_user(argp, &wdinfo, sizeof(wdinfo)))
            return -EFAULT;
        return 0;

    case WDIOC_GETSTATUS:
        i = wdrtas_get_status();
        return put_user(i, argp);

    case WDIOC_GETBOOTSTATUS:
        i = wdrtas_get_boot_status();
        return put_user(i, argp);

    case WDIOC_GETTEMP:
        if (wdrtas_token_get_sensor_state == RTAS_UNKNOWN_SERVICE)
            return -EOPNOTSUPP;

        i = wdrtas_get_temperature();
        return put_user(i, argp);

    case WDIOC_SETOPTIONS:
        if (get_user(i, argp))
            return -EFAULT;
        if (i & WDIOS_DISABLECARD)
            wdrtas_timer_stop();
        if (i & WDIOS_ENABLECARD) {
            wdrtas_timer_keepalive();
            wdrtas_timer_start();
        }
        /* not implemented. Done by H8
        if (i & WDIOS_TEMPPANIC) {
        } */
        return 0;

    case WDIOC_KEEPALIVE:
        wdrtas_timer_keepalive();
        return 0;

    case WDIOC_SETTIMEOUT:
        if (get_user(i, argp))
            return -EFAULT;

        if (wdrtas_set_interval(i))
            return -EINVAL;

        wdrtas_timer_keepalive();

        if (wdrtas_token_get_sp == RTAS_UNKNOWN_SERVICE)
            wdrtas_interval = i;
        else
            wdrtas_interval = wdrtas_get_interval(i);
        /* fallthrough */

    case WDIOC_GETTIMEOUT:
        return put_user(wdrtas_interval, argp);

    default:
        return -ENOTTY;
    }
}

static int wdrtas_open(struct inode *inode, struct file *file)
{
    /* only open once */
    if (atomic_inc_return(&wdrtas_miscdev_open) > 1) {
        atomic_dec(&wdrtas_miscdev_open);
        return -EBUSY;
    }

    wdrtas_timer_start();
    wdrtas_timer_keepalive();

    return nonseekable_open(inode, file);
}

static int wdrtas_close(struct inode *inode, struct file *file)
{
    /* only stop watchdog, if this was announced using 'V' before */
    if (wdrtas_expect_close == WDRTAS_MAGIC_CHAR)
        wdrtas_timer_stop();
    else {
        pr_warn("got unexpected close. Watchdog not stopped.\n");
        wdrtas_timer_keepalive();
    }

    wdrtas_expect_close = 0;
    atomic_dec(&wdrtas_miscdev_open);
    return 0;
}

static ssize_t wdrtas_temp_read(struct file *file, char __user *buf,
         size_t count, loff_t *ppos)
{
    int temperature = 0;

    temperature = wdrtas_get_temperature();
    if (temperature < 0)
        return temperature;

    if (copy_to_user(buf, &temperature, 1))
        return -EFAULT;

    return 1;
}

static int wdrtas_temp_open(struct inode *inode, struct file *file)
{
    return nonseekable_open(inode, file);
}

static int wdrtas_temp_close(struct inode *inode, struct file *file)
{
    return 0;
}

static int wdrtas_reboot(struct notifier_block *this,
                    unsigned long code, void *ptr)
{
    if (code == SYS_DOWN || code == SYS_HALT)
        wdrtas_timer_stop();

    return NOTIFY_DONE;
}

/*** initialization stuff */

static const struct file_operations wdrtas_fops = {
    .owner      = THIS_MODULE,
    .llseek     = no_llseek,
    .write      = wdrtas_write,
    .unlocked_ioctl = wdrtas_ioctl,
    .open       = wdrtas_open,
    .release    = wdrtas_close,
};

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

static const struct file_operations wdrtas_temp_fops = {
    .owner      = THIS_MODULE,
    .llseek     = no_llseek,
    .read       = wdrtas_temp_read,
    .open       = wdrtas_temp_open,
    .release    = wdrtas_temp_close,
};

static struct miscdevice wdrtas_tempdev = {
    .minor =    TEMP_MINOR,
    .name =     "temperature",
    .fops =     &wdrtas_temp_fops,
};

static struct notifier_block wdrtas_notifier = {
    .notifier_call =    wdrtas_reboot,
};

static int wdrtas_get_tokens(void)
{
    wdrtas_token_get_sensor_state = rtas_token("get-sensor-state");
    if (wdrtas_token_get_sensor_state == RTAS_UNKNOWN_SERVICE) {
        pr_warn("couldn't get token for get-sensor-state. Trying to continue without temperature support.\n");
    }

    wdrtas_token_get_sp = rtas_token("ibm,get-system-parameter");
    if (wdrtas_token_get_sp == RTAS_UNKNOWN_SERVICE) {
        pr_warn("couldn't get token for ibm,get-system-parameter. Trying to continue with a default timeout value of %i seconds.\n",
            WDRTAS_DEFAULT_INTERVAL);
    }

    wdrtas_token_set_indicator = rtas_token("set-indicator");
    if (wdrtas_token_set_indicator == RTAS_UNKNOWN_SERVICE) {
        pr_err("couldn't get token for set-indicator. Terminating watchdog code.\n");
        return -EIO;
    }

    wdrtas_token_event_scan = rtas_token("event-scan");
    if (wdrtas_token_event_scan == RTAS_UNKNOWN_SERVICE) {
        pr_err("couldn't get token for event-scan. Terminating watchdog code.\n");
        return -EIO;
    }

    return 0;
}

static void wdrtas_unregister_devs(void)
{
    misc_deregister(&wdrtas_miscdev);
    if (wdrtas_token_get_sensor_state != RTAS_UNKNOWN_SERVICE)
        misc_deregister(&wdrtas_tempdev);
}

static int wdrtas_register_devs(void)
{
    int result;

    result = misc_register(&wdrtas_miscdev);
    if (result) {
        pr_err("couldn't register watchdog misc device. Terminating watchdog code.\n");
        return result;
    }

    if (wdrtas_token_get_sensor_state != RTAS_UNKNOWN_SERVICE) {
        result = misc_register(&wdrtas_tempdev);
        if (result) {
            pr_warn("couldn't register watchdog temperature misc device. Continuing without temperature support.\n");
            wdrtas_token_get_sensor_state = RTAS_UNKNOWN_SERVICE;
        }
    }

    return 0;
}

static int __init wdrtas_init(void)
{
    if (wdrtas_get_tokens())
        return -ENODEV;

    if (wdrtas_register_devs())
        return -ENODEV;

    if (register_reboot_notifier(&wdrtas_notifier)) {
        pr_err("could not register reboot notifier. Terminating watchdog code.\n");
        wdrtas_unregister_devs();
        return -ENODEV;
    }

    if (wdrtas_token_get_sp == RTAS_UNKNOWN_SERVICE)
        wdrtas_interval = WDRTAS_DEFAULT_INTERVAL;
    else
        wdrtas_interval = wdrtas_get_interval(WDRTAS_DEFAULT_INTERVAL);

    return 0;
}

static void __exit wdrtas_exit(void)
{
    if (!wdrtas_nowayout)
        wdrtas_timer_stop();

    wdrtas_unregister_devs();

    unregister_reboot_notifier(&wdrtas_notifier);
}

module_init(wdrtas_init);
module_exit(wdrtas_exit);