wdrtas.c

linux-2.6.15.6

/*
 * 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 <[e-mail]>
 *
 * 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/config.h>
#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 <[e-mail]>");
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();