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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 <utz.bacher@de.ibm.com>

 *

 * 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.

 */

#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 <asm/rtas.h>

#include <asm/uaccess.h>

#define WDRTAS_MAGIC_CHAR               42

#define WDRTAS_SUPPORTED_MASK           (WDIOF_SETTIMEOUT | \

                                         WDIOF_MAGICCLOSE)

MODULE_AUTHOR("Utz Bacher <utz.bacher@de.ibm.com>");

MODULE_DESCRIPTION("RTAS watchdog driver");

MODULE_LICENSE("GPL");

MODULE_ALIAS_MISCDEV(WATCHDOG_MINOR);

MODULE_ALIAS_MISCDEV(TEMP_MINOR);

#ifdef CONFIG_WATCHDOG_NOWAYOUT

static int wdrtas_nowayout = 1;

#else

static int wdrtas_nowayout = 0;

#endif

static atomic_t wdrtas_miscdev_open = ATOMIC_INIT(0);

static char wdrtas_expect_close = 0;

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 */

/**

 * wdrtas_set_interval - sets the watchdog interval

 * @interval: new interval

 *

 * returns 0 on success, <0 on failures

 *

 * wdrtas_set_interval sets the watchdog keepalive interval by calling the

 * RTAS function set-indicator (surveillance). The unit of interval is

 * seconds.

 */

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) ) {

                printk(KERN_ERR "wdrtas: setting the watchdog to %i "

                       "timeout failed: %li\n", interval, result);

                print_msg--;

        }

        return result;

}

/**

 * wdrtas_get_interval - returns the current watchdog interval

 * @fallback_value: value (in seconds) to use, if the RTAS call fails

 *

 * returns the interval

 *

 * wdrtas_get_interval returns the current watchdog keepalive interval

 * as reported by the RTAS function ibm,get-system-parameter. The unit

 * of the return value is seconds.

 */

static int

wdrtas_get_interval(int fallback_value)

{

        long result;

        char value[4];

        result = rtas_call(wdrtas_token_get_sp, 3, 1, NULL,

                           WDRTAS_SP_SPI, (void *)__pa(&value), 4);

        if ( (value[0] != 0) || (value[1] != 2) || (value[3] != 0) ||

             (result < 0) ) {

                printk(KERN_WARNING "wdrtas: could not get sp_spi watchdog "

                       "timeout (%li). Continuing\n", result);

                return fallback_value;

        }

        /* rtas uses minutes */

        return ((int)value[2]) * 60;

}

/**

 * wdrtas_timer_start - starts watchdog

 *

 * wdrtas_timer_start starts the watchdog by calling the RTAS function

 * set-interval (surveillance)

 */

static void

wdrtas_timer_start(void)

{

        wdrtas_set_interval(wdrtas_interval);

}

/**

 * wdrtas_timer_stop - stops watchdog

 *

 * wdrtas_timer_stop stops the watchdog timer by calling the RTAS function

 * set-interval (surveillance)

 */

static void

wdrtas_timer_stop(void)

{

        wdrtas_set_interval(0);

}

/**

 * wdrtas_log_scanned_event - logs an event we received during keepalive

 *

 * wdrtas_log_scanned_event prints a message to the log buffer dumping

 * the results of the last event-scan call

 */

static void

wdrtas_log_scanned_event(void)

{

        int i;

        for (i = 0; i < WDRTAS_LOGBUFFER_LEN; i += 16)

                printk(KERN_INFO "wdrtas: 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]);

}

/**

 * wdrtas_timer_keepalive - resets watchdog timer to keep system alive

 *

 * wdrtas_timer_keepalive restarts the watchdog timer by calling the

 * RTAS function event-scan and repeats these calls as long as there are

 * events available. All events will be dumped.

 */

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)

                        printk(KERN_ERR "wdrtas: event-scan failed: %li\n",

                               result);

                if (result == 0)

                        wdrtas_log_scanned_event();

        } while (result == 0);

}

/**

 * wdrtas_get_temperature - returns current temperature

 *

 * returns temperature or <0 on failures

 *

 * wdrtas_get_temperature returns the current temperature in Fahrenheit. It

 * uses the RTAS call get-sensor-state, token 3 to do so

 */

static int

wdrtas_get_temperature(void)

{

        long result;

        int temperature = 0;

        result = rtas_call(wdrtas_token_get_sensor_state, 2, 2,

                           (void *)__pa(&temperature),

                           WDRTAS_THERMAL_SENSOR, 0);

        if (result < 0)

                printk(KERN_WARNING "wdrtas: reading the thermal sensor "

                       "faild: %li\n", result);

        else

                temperature = ((temperature * 9) / 5) + 32; /* fahrenheit */

        return temperature;

}

/**

 * wdrtas_get_status - returns the status of the watchdog

 *

 * returns a bitmask of defines WDIOF_... as defined in

 * include/linux/watchdog.h

 */

static int

wdrtas_get_status(void)

{

        return 0; /* TODO */

}

/**

 * wdrtas_get_boot_status - returns the reason for the last boot

 *

 * returns a bitmask of defines WDIOF_... as defined in

 * include/linux/watchdog.h, indicating why the watchdog rebooted the system

 */

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;

}

/**

 * wdrtas_ioctl - ioctl function for the watchdog device

 * @inode: inode structure

 * @file: file structure

 * @cmd: command for ioctl

 * @arg: argument pointer

 *

 * returns 0 on success, <0 on failure

 *

 * wdrtas_ioctl implements the watchdog API ioctls

 */

static int

wdrtas_ioctl(struct inode *inode, struct file *file,

             unsigned int cmd, unsigned long arg)

{

        int __user *argp = (void __user *)arg;

        int i;

        static 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();

                }

                if (i & WDIOS_TEMPPANIC) {

                        /* not implemented. Done by H8 */

                }

                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;

        }

}

/**

 * wdrtas_open - open function of watchdog device

 * @inode: inode structure

 * @file: file structure

 *

 * returns 0 on success, -EBUSY if the file has been opened already, <0 on

 * other failures

 *

 * function called when watchdog device is opened

 */

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);

}

/**

 * wdrtas_close - close function of watchdog device

 * @inode: inode structure

 * @file: file structure

 *

 * returns 0 on success

 *

 * close function. Always succeeds

 */

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 {

                printk(KERN_WARNING "wdrtas: got unexpected close. Watchdog "

                       "not stopped.\n");

                wdrtas_timer_keepalive();

        }

        wdrtas_expect_close = 0;

        atomic_dec(&wdrtas_miscdev_open);

        return 0;

}

/**

 * wdrtas_temp_read - gives back the temperature in fahrenheit

 * @file: file structure

 * @buf: user buffer

 * @count: number of bytes to be read

 * @ppos: position in file

 *

 * returns always 1 or -EFAULT in case of user space copy failures, <0 on

 * other failures

 *

 * wdrtas_temp_read gives the temperature to the users by copying this

 * value as one byte into the user space buffer. The unit is Fahrenheit...

 */

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;

}

/**

 * wdrtas_temp_open - open function of temperature device

 * @inode: inode structure

 * @file: file structure

 *

 * returns 0 on success, <0 on failure

 *

 * function called when temperature device is opened

 */

static int

wdrtas_temp_open(struct inode *inode, struct file *file)

{

        return nonseekable_open(inode, file);

}

/**

 * wdrtas_temp_close - close function of temperature device

 * @inode: inode structure

 * @file: file structure

 *

 * returns 0 on success

 *

 * close function. Always succeeds

 */

static int

wdrtas_temp_close(struct inode *inode, struct file *file)

{

        return 0;

}

/**

 * wdrtas_reboot - reboot notifier function

 * @nb: notifier block structure

 * @code: reboot code

 * @ptr: unused

 *

 * returns NOTIFY_DONE

 *

 * wdrtas_reboot stops the watchdog in case of a reboot

 */

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,

        .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,

};

/**

 * wdrtas_get_tokens - reads in RTAS tokens

 *

 * returns 0 on succes, <0 on failure

 *

 * wdrtas_get_tokens reads in the tokens for the RTAS calls used in

 * this watchdog driver. It tolerates, if "get-sensor-state" and

 * "ibm,get-system-parameter" are not available.

 */

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) {

                printk(KERN_WARNING "wdrtas: 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) {

                printk(KERN_WARNING "wdrtas: 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) {

                printk(KERN_ERR "wdrtas: 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) {

                printk(KERN_ERR "wdrtas: couldn't get token for event-scan. "

                       "Terminating watchdog code.\n");

                return -EIO;

        }

        return 0;

}

/**

 * wdrtas_unregister_devs - unregisters the misc dev handlers

 *

 * wdrtas_register_devs unregisters the watchdog and temperature watchdog

 * misc devs

 */

static void

wdrtas_unregister_devs(void)

{

        misc_deregister(&wdrtas_miscdev);

        if (wdrtas_token_get_sensor_state != RTAS_UNKNOWN_SERVICE)

                misc_deregister(&wdrtas_tempdev);

}

/**

 * wdrtas_register_devs - registers the misc dev handlers

 *

 * returns 0 on succes, <0 on failure

 *

 * wdrtas_register_devs registers the watchdog and temperature watchdog

 * misc devs

 */

static int

wdrtas_register_devs(void)

{

        int result;

        result = misc_register(&wdrtas_miscdev);

        if (result) {

                printk(KERN_ERR "wdrtas: 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) {

                        printk(KERN_WARNING "wdrtas: couldn't register "

                               "watchdog temperature misc device. Continuing "

                               "without temperature support.\n");

                        wdrtas_token_get_sensor_state = RTAS_UNKNOWN_SERVICE;

                }

        }

        return 0;

}

/**

 * wdrtas_init - init function of the watchdog driver

 *

 * returns 0 on succes, <0 on failure

 *

 * registers the file handlers and the reboot notifier

 */

static int __init

wdrtas_init(void)

{

        if (wdrtas_get_tokens())

                return -ENODEV;

        if (wdrtas_register_devs())

                return -ENODEV;

        if (register_reboot_notifier(&wdrtas_notifier)) {

                printk(KERN_ERR "wdrtas: 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;

}

/**

 * wdrtas_exit - exit function of the watchdog driver

 *

 * unregisters the file handlers and the reboot notifier

 */

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);