2.3-InternetRadio/nutos/nut/arch/avr/dev/wdt_avr.c

/*
 * Copyright (C) 2006 by egnite Software GmbH. All rights reserved.
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 * modification, are permitted provided that the following conditions
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 *
 * 1. Redistributions of source code must retain the above copyright
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 *    notice, this list of conditions and the following disclaimer in the
 *    documentation and/or other materials provided with the distribution.
 * 3. Neither the name of the copyright holders nor the names of
 *    contributors may be used to endorse or promote products derived
 *    from this software without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
 * ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
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/*!
 * \file arch/avr/dev/wdt_avr.c
 * \brief AVR watchdog support.
 *
 * \verbatim
 * $Id: wdt_avr.c 4706 2012-10-06 17:42:01Z haraldkipp $
 * \endverbatim
 */

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

/*!
 * \addtogroup xgNutArchAvrDevWatchDog
 */
/*@{*/

/*!
 * \brief Watchdog oscillator frequency.
 */
#ifndef NUT_WDT_FREQ
#define NUT_WDT_FREQ    1165000
#endif

static ureg_t nested;
static uint8_t wdt_div;


/*!
 * \brief Start the AVR hardware watch dog timer.
 *
 * For portability, applications should use the platform independent
 * \ref xgWatchDog "Watchdog Driver API".
 *
 * \param ms Desired watchdog timeout in milliseconds.
 *
 * \return The actual watchdog timeout.
 */
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);
}

/*!
 * \brief Re-start the AVR hardware watch dog timer.
 *
 * For portability, applications should use the platform independent
 * \ref xgWatchDog "Watchdog Driver API".
 */
void AvrWatchDogRestart(void)
{
    wdt_reset();
}

/*!
 * \brief Disable the AVR hardware watch dog timer.
 *
 * For portability, applications should use the platform independent
 * \ref xgWatchDog "Watchdog Driver API".
 */
void AvrWatchDogDisable(void)
{
    if (nested) {
        nested++;
    }
    wdt_disable();
}

/*!
 * \brief Enable the AVR hardware watch dog timer.
 *
 * For portability, applications should use the platform independent
 * \ref xgWatchDog "Watchdog Driver API".
 */
void AvrWatchDogEnable(void)
{
    if (nested > 1 && --nested == 1) {
        wdt_enable(wdt_div);
    }
}

/*@}*/