wdt_avr.c

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/*
 * Copyright (C) 2006 by egnite Software GmbH. All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
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 *
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 *    notice, this list of conditions and the following disclaimer in the
 *    documentation and/or other materials provided with the distribution.
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 *    from this software without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY EGNITE SOFTWARE GMBH AND CONTRIBUTORS
 * ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
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/*
 * $Log$
 * Revision 1.2  2008/08/11 06:59:18  haraldkipp
 * BSD types replaced by stdint types (feature request #1282721).
 *
 * Revision 1.1  2006/05/25 09:13:23  haraldkipp
 * Platform independent watchdog API added.
 *
 */

#if defined(__GNUC__)
#include <avr/wdt.h>
#endif
#include <sys/timer.h>
#include <dev/watchdog.h>


#ifndef NUT_WDT_FREQ
#define NUT_WDT_FREQ    1165000
#endif

static ureg_t nested;
static uint8_t wdt_div;


uint32_t AvrWatchDogStart(uint32_t ms)
{
    uint32_t ticks;

    wdt_reset();

    ticks = ((NUT_WDT_FREQ / 1000UL) * ms) >> 14;
    for (wdt_div = 0; wdt_div < 7 && ticks; wdt_div++) {
        ticks >>= 1;
    }
    wdt_enable(wdt_div);
    
    nested = 1;

    return (16384UL << wdt_div) / (NUT_WDT_FREQ / 1000UL);
}

void AvrWatchDogRestart(void)
{
    wdt_reset();
}

void AvrWatchDogDisable(void)
{
    if (nested) {
        nested++;
    }
    wdt_disable();
}

void AvrWatchDogEnable(void)
{
    if (nested > 1 && --nested == 1) {
        wdt_enable(wdt_div);
    }
}