2.3-InternetRadio/nutos/nut/arch/m68k/coldfire/dev/mcf5225x/mcf5225x_ostimer.c

/*
 * Copyright 2012 by Embedded Technologies s.r.o
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 *
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright
 *    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
 * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
 * FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
 * COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
 * BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS
 * OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED
 * AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
 * OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF
 * THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
 * SUCH DAMAGE.
 *
 * For additional information see http://www.ethernut.de/
 */
#include <cfg/os.h>
#include <cfg/clock.h>

#include <arch/m68k.h>
#include <dev/irqreg.h>
#include <sys/timer.h>

/*!
 * \addtogroup xgNutArchM68kMCF5225XOsTimer
 */
/*@{*/

#ifndef NUT_TICK_FREQ
/*!
 * \brief System timer interrupt frequency.
 *
 * Specifies the number of interrupts per second, typically 1000.
 * In order to reduce overhead, you may choose lower values. Note,
 * that Nut/OS API timer values are given in milliseconds. Thus,
 * lower values will reduce the available resolution, while
 * larger values may not provide any benefit.
 */
#define NUT_TICK_FREQ       1000UL
#endif

#define EXT_CLOCK_HZ        48000000UL
#define CHANEL              0   /* PIT0 */

/*!
 * \brief Initialize system timer.
 *
 * Applications must not call this function.
 *
 * It is automatically called by Nut/OS during initialization to register
 * the system timer interrupt handler. It is an essential part of the
 * hardware dependant code and must be available for any platform that is
 * running Nut/OS.
 *
 * The number of system timer interrupts is define by \ref NUT_TICK_FREQ.
 *
 * Timer interrupts are enabled when this function returns.
 *
 * \param handler This routine should be called each time, when a 
 *                system timer interrupt occurs.
 */
void NutRegisterTimer(void (*handler) (void *))
{
    /*
     * Note, that this timer will no longer be available for
     * applications.
     */
     
    uint8_t prescaler = 0;
    uint32_t modulus;

    /*
     * It is recommended to use NutClockGet() to determine the input
     * clock frequency.
     * 
     * Count PIT Count Register value.
     * Timeout Frequency = fsys/2 / (2^PCSRn[PRE] * (PMRn[PM] + 1)) in Hertz
     * PMRn[PM] = (fsys/2 / (2^PCSRn[PRE] * NUT_TICK_FREQ)) - 1
     */
    modulus = NutClockGet() / 2;
    modulus /= 1 << prescaler;
    modulus /= NUT_TICK_FREQ;
    modulus--;

    /* The prescaler bits select the internal bus clock divisor to generate the PIT clock. */
    MCF_PIT_PCSR(CHANEL) = 0x00 | MCF_PIT_PCSR_PRE(prescaler);

    /* Set PIT Count Register value. */
    MCF_PIT_PMR(CHANEL) = modulus;

    /* Enable reload for periodic mode */
    MCF_PIT_PCSR(CHANEL) |= MCF_PIT_PCSR_RLD;

    /* Init Interrupt */
    NutRegisterIrqHandler(&sig_PIT0, handler, NULL);

    /*
     * Enable PIT interrup and clear interrupt flag
     * NOTE: Interrupt is still disabled by interrupt controller.
     */
    MCF_PIT_PCSR(CHANEL) |= MCF_PIT_PCSR_PIE | MCF_PIT_PCSR_PIF;

    /* Enable timer */
    MCF_PIT_PCSR(CHANEL) |= MCF_PIT_PCSR_EN | MCF_PIT_PCSR_DBG;
}

#ifndef NUT_CPU_FREQ
/*!
 * \brief Return the specified clock frequency.
 *
 * Applications must not call this function, but use NutClockGet()
 * instead.
 *
 * Simple implementations may not provide this function, in which case
 * \ref NUT_CPU_FREQ must define the CPU frequency in Hertz. This can
 * be done in the Configurator.
 *
 * \param idx This zero based index specifies the clock to retrieve. The
 *            number of available hardware clocks depends on the target
 *            harware and is specified by NUT_HWCLK_MAX + 1. Typically
 *            \ref NUT_HWCLK_CPU is used to retrieve the current CPU
 *            clock. Additional indices may be available to retrieve one
 *            or more peripheral clocks or a special slow clock.
 *
 * \return Clock frequency in Hertz.
 */
uint32_t NutArchClockGet(int idx)
 {
    int fout, fref, mfd, rfd, divider, lpdr;

    /* The PLL pre divider - 48MHz / (CCHR + 1) = 8MHz */
    divider = MCF_CLOCK_CCHR + 1;
    fref = EXT_CLOCK_HZ / divider;

    /* The LPDR divides down the system clock by a factor of 2^LPDR. */
    lpdr = 1 << MCF_CLOCK_LPDR;


    mfd = (MCF_CLOCK_SYNCR & 0x7000) >> 12;
    mfd = 2 * (mfd + 2); // MIN_MFD
    rfd = (MCF_CLOCK_SYNCR & 0x0700) >> 8;
    rfd = 1 << rfd;

    /* Return current PLL output */
    if ((MCF_CLOCK_SYNCR & MCF_CLOCK_SYNCR_CLKSRC) && (MCF_CLOCK_SYNCR & MCF_CLOCK_SYNCR_PLLEN)) {
        fout = (fref * (mfd / rfd)) / lpdr;
    } else {
        fout = fref / lpdr;
    }
    return fout;
}
#endif

/*!
 * \brief Return the number of system ticks per second.
 *
 * This routine is used by Nut/OS to convert tick counts into
 * milliseconds.
 *
 * Applications typically do not deal with system ticks. Instead,
 * they use milliseconds to specify timeouts or call NutGetMillis()
 * and NutGetSeconds() to retrieve an elapsed time.
 *
 * \return System tick frequency in Hertz, typically the value of
 *         \ref NUT_TICK_FREQ.
 */
uint32_t NutGetTickClock(void)
{
    return NUT_TICK_FREQ;
}

/*!
 * \brief Calculate system ticks for a given number of milliseconds.
 *
 * This routine is used by Nut/OS to retrieve the number of system
 * ticks for a given timeout.
 *
 * \param ms Number of milliseconds.
 *
 * \return Number of system ticks. The resolution is limited to the
 *         granularity of the system timer.
 */
uint32_t NutTimerMillisToTicks(uint32_t ms)
{
    return (ms * NutGetTickClock()) / 1000;
}

/*@}*/