wdt.c

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/*
 * $Log: wdt.c,v $
 *
 */

#include <sys/timer.h>
#include <dev/watchdog.h>
#include <arch/avr32.h>

#include <avr32/io.h>

// AP7000 includes lack this define, even though they are the same as UC30512
#if !defined(AVR32_WDT_KEY_VALUE)
#define AVR32_WDT_KEY_VALUE                            0x00000055
#endif


static ureg_t nested;

static void wdt_set_ctrl(unsigned long ctrl)
{
    AVR32_WDT.ctrl = ctrl | (AVR32_WDT_KEY_VALUE << AVR32_WDT_CTRL_KEY_OFFSET);
    AVR32_WDT.ctrl = ctrl | ((~AVR32_WDT_KEY_VALUE << AVR32_WDT_CTRL_KEY_OFFSET) & AVR32_WDT_CTRL_KEY_MASK);
}

static long long wdt_get_us_timeout_period(void)
{
    unsigned int slowclock = NutArchClockGet(NUT_HWCLK_SLOW_CLOCK);
    // Read CTRL.PSEL and translate it into us.
    return (AVR32_WDT.ctrl & AVR32_WDT_CTRL_EN_MASK) ?
        ((1ULL << (((AVR32_WDT.ctrl & AVR32_WDT_CTRL_PSEL_MASK) >> AVR32_WDT_CTRL_PSEL_OFFSET) + 1)) *
         1000000 + slowclock / 2) / slowclock : -1;
}

uint32_t Avr32WatchDogStart(uint32_t ms)
{
    unsigned long long int timeout = ms * 1000;

    unsigned int slowclock = NutArchClockGet(NUT_HWCLK_SLOW_CLOCK);

    Avr32WatchDogDisable();

#define MIN_US_TIMEOUT_PERIOD  \
        (((1ULL <<  1 ) * 1000000 + slowclock / 2) / slowclock)
#define MAX_US_TIMEOUT_PERIOD  \
        (((1ULL << (1 << AVR32_WDT_CTRL_PSEL_SIZE)) * 1000000 + slowclock / 2) / slowclock)

    // Set the CTRL.EN bit and translate the us timeout to fit in CTRL.PSEL using
    // the formula wdt = 2pow(PSEL+1) / fRCosc in useconds.
    if (timeout < MIN_US_TIMEOUT_PERIOD)
        timeout = MIN_US_TIMEOUT_PERIOD;
    else if (timeout > MAX_US_TIMEOUT_PERIOD)
        timeout = MAX_US_TIMEOUT_PERIOD;

    wdt_set_ctrl(AVR32_WDT_CTRL_EN_MASK |
                 ((32 - __builtin_clz(((((timeout * slowclock + 500000) / 1000000) << 1) - 1) >> 1) -
                   1) << AVR32_WDT_CTRL_PSEL_OFFSET));

    Avr32WatchDogRestart();
    nested = 1;

    // Return the actual wdt period in us.
    return wdt_get_us_timeout_period() / 1000;
}

void Avr32WatchDogRestart(void)
{
    wdt_set_ctrl(AVR32_WDT.ctrl | AVR32_WDT_CTRL_EN_MASK);
    AVR32_WDT.clr = 0;
}

void Avr32WatchDogDisable(void)
{
    if (nested) {
        nested++;
    }
    wdt_set_ctrl(AVR32_WDT.ctrl & ~AVR32_WDT_CTRL_EN_MASK);
}

void Avr32WatchDogEnable(void)
{
    if (nested > 1 && --nested == 1) {
        Avr32WatchDogRestart();
    }
}