Subversion Repositories openrisc_2011-10-31

/* ----------------------------------------------------------------------------

 *         ATMEL Microcontroller Software Support

 * ----------------------------------------------------------------------------

 * Copyright (c) 2008, Atmel Corporation

 *

 * All rights reserved.

 *

 * Redistribution and use in source and binary forms, with or without

 * modification, are permitted provided that the following conditions are met:

 *

 * - Redistributions of source code must retain the above copyright notice,

 * this list of conditions and the disclaimer below.

 *

 * Atmel's name may not be used to endorse or promote products derived from

 * this software without specific prior written permission.

 *

 * DISCLAIMER: THIS SOFTWARE IS PROVIDED BY ATMEL "AS IS" AND ANY EXPRESS OR

 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF

 * MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NON-INFRINGEMENT ARE

 * DISCLAIMED. IN NO EVENT SHALL ATMEL 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.

 * ----------------------------------------------------------------------------

 */

//------------------------------------------------------------------------------

//         Headers

//------------------------------------------------------------------------------

#include "pwmc.h"

#include <board.h>

#include <utility/assert.h>

#include <utility/trace.h>

//------------------------------------------------------------------------------

//         Local functions

//------------------------------------------------------------------------------

//------------------------------------------------------------------------------

/// Finds a prescaler/divisor couple to generate the desired frequency from

/// MCK.

/// Returns the value to enter in PWMC_MR or 0 if the configuration cannot be

/// met.

/// \param frequency  Desired frequency in Hz.

/// \param mck  Master clock frequency in Hz.

//------------------------------------------------------------------------------

static unsigned short FindClockConfiguration(

    unsigned int frequency,

    unsigned int mck)

{

    unsigned int divisors[11] = {1, 2, 4, 8, 16, 32, 64, 128, 256, 512, 1024};

    unsigned char divisor = 0;

    unsigned int prescaler;

    SANITY_CHECK(frequency < mck);

    // Find prescaler and divisor values

    prescaler = (mck / divisors[divisor]) / frequency;

    while ((prescaler > 255) && (divisor < 11)) {

        divisor++;

        prescaler = (mck / divisors[divisor]) / frequency;

    }

    // Return result

    if (divisor < 11) {

        trace_LOG(trace_DEBUG, "-D- Found divisor=%u and prescaler=%u for freq=%uHz\n\r",

                  divisors[divisor], prescaler, frequency);

        return prescaler | (divisor << 8);

    }

    else {

        return 0;

    }

}

//------------------------------------------------------------------------------

//         Global functions

//------------------------------------------------------------------------------

//------------------------------------------------------------------------------

/// Configures PWM a channel with the given parameters.

/// The PWM controller must have been clocked in the PMC prior to calling this

/// function.

/// \param channel  Channel number.

/// \param prescaler  Channel prescaler.

/// \param alignment  Channel alignment.

/// \param polarity  Channel polarity.

//------------------------------------------------------------------------------

void PWMC_ConfigureChannel(

    unsigned char channel,

    unsigned int prescaler,

    unsigned int alignment,

    unsigned int polarity)

{

    SANITY_CHECK(prescaler < AT91C_PWMC_CPRE_MCKB);

    SANITY_CHECK((alignment & ~AT91C_PWMC_CALG) == 0);

    SANITY_CHECK((polarity & ~AT91C_PWMC_CPOL) == 0);

    // Disable channel

    AT91C_BASE_PWMC->PWMC_DIS = 1 << channel;

    // Configure channel

    AT91C_BASE_PWMC->PWMC_CH[channel].PWMC_CMR = prescaler | alignment | polarity;

}

//------------------------------------------------------------------------------

/// Configures PWM clocks A & B to run at the given frequencies. This function

/// finds the best MCK divisor and prescaler values automatically.

/// \param clka  Desired clock A frequency (0 if not used).

/// \param clkb  Desired clock B frequency (0 if not used).

/// \param mck  Master clock frequency.

//------------------------------------------------------------------------------

void PWMC_ConfigureClocks(unsigned int clka, unsigned int clkb, unsigned int mck)

{

    unsigned int mode = 0;

    unsigned int result;

    // Clock A

    if (clka != 0) {

        result = FindClockConfiguration(clka, mck);

        ASSERT(result != 0, "-F- Could not generate the desired PWM frequency (%uHz)\n\r", clka);

        mode |= result;

    }

    // Clock B

    if (clkb != 0) {

        result = FindClockConfiguration(clkb, mck);

        ASSERT(result != 0, "-F- Could not generate the desired PWM frequency (%uHz)\n\r", clkb);

        mode |= (result << 16);

    }

    // Configure clocks

    trace_LOG(trace_DEBUG, "-D- Setting PWMC_MR = 0x%08X\n\r", mode);

    AT91C_BASE_PWMC->PWMC_MR = mode;

}

//------------------------------------------------------------------------------

/// Sets the period value used by a PWM channel. This function writes directly

/// to the CPRD register if the channel is disabled; otherwise, it uses the

/// update register CUPD.

/// \param channel  Channel number.

/// \param period  Period value.

//------------------------------------------------------------------------------

void PWMC_SetPeriod(unsigned char channel, unsigned short period)

{

    // If channel is disabled, write to CPRD

    if ((AT91C_BASE_PWMC->PWMC_SR & (1 << channel)) == 0) {

        AT91C_BASE_PWMC->PWMC_CH[channel].PWMC_CPRDR = period;

    }

    // Otherwise use update register

    else {

        AT91C_BASE_PWMC->PWMC_CH[channel].PWMC_CMR |= AT91C_PWMC_CPD;

        AT91C_BASE_PWMC->PWMC_CH[channel].PWMC_CUPDR = period;

    }

}

//------------------------------------------------------------------------------

/// Sets the duty cycle used by a PWM channel. This function writes directly to

/// the CDTY register if the channel is disabled; otherwise it uses the

/// update register CUPD.

/// Note that the duty cycle must always be inferior or equal to the channel

/// period.

/// \param channel  Channel number.

/// \param duty  Duty cycle value.

//------------------------------------------------------------------------------

void PWMC_SetDutyCycle(unsigned char channel, unsigned short duty)

{

    SANITY_CHECK(duty <= AT91C_BASE_PWMC->PWMC_CH[channel].PWMC_CPRDR);

    // SAM7S errata

#if defined(at91sam7s16) || defined(at91sam7s161) || defined(at91sam7s32) \

    || defined(at91sam7s321) || defined(at91sam7s64) || defined(at91sam7s128) \

    || defined(at91sam7s256) || defined(at91sam7s512)

    ASSERT(duty > 0, "-F- Duty cycle value 0 is not permitted on SAM7S chips.\n\r");

    ASSERT((duty > 1) || (AT91C_BASE_PWMC->PWMC_CH[channel].PWMC_CMR & AT91C_PWMC_CALG),

           "-F- Duty cycle value 1 is not permitted in left-aligned mode on SAM7S chips.\n\r");

#endif

    // If channel is disabled, write to CDTY

    if ((AT91C_BASE_PWMC->PWMC_SR & (1 << channel)) == 0) {

        AT91C_BASE_PWMC->PWMC_CH[channel].PWMC_CDTYR = duty;

    }

    // Otherwise use update register

    else {

        AT91C_BASE_PWMC->PWMC_CH[channel].PWMC_CMR &= ~AT91C_PWMC_CPD;

        AT91C_BASE_PWMC->PWMC_CH[channel].PWMC_CUPDR = duty;

    }

}

//------------------------------------------------------------------------------

/// Enables the given PWM channel. This does NOT enable the corresponding pin;

/// this must be done in the user code.

/// \param channel  Channel number.

//------------------------------------------------------------------------------

void PWMC_EnableChannel(unsigned char channel)

{

    AT91C_BASE_PWMC->PWMC_ENA = 1 << channel;

}

//------------------------------------------------------------------------------

/// Disables the given PWM channel.

/// \param channel  Channel number.

//------------------------------------------------------------------------------

void PWMC_DisableChannel(unsigned char channel)

{

    AT91C_BASE_PWMC->PWMC_DIS = 1 << channel;

}

//------------------------------------------------------------------------------

/// Enables the period interrupt for the given PWM channel.

/// \param channel  Channel number.

//------------------------------------------------------------------------------

void PWMC_EnableChannelIt(unsigned char channel)

{

    AT91C_BASE_PWMC->PWMC_IER = 1 << channel;

}

//------------------------------------------------------------------------------

/// Disables the period interrupt for the given PWM channel.

/// \param channel  Channel number.

//------------------------------------------------------------------------------

void PWMC_DisableChannelIt(unsigned char channel)

{

    AT91C_BASE_PWMC->PWMC_IDR = 1 << channel;

}