Subversion Repositories openrisc

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

 *         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.

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

 */

#ifndef trace_LEVEL

    #define trace_LEVEL  1

#endif

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

//         Headers

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

#include "twi.h"

#include <utility/math.h>

#include <utility/assert.h>

#include <utility/trace.h>

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

//         Global functions

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

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

/// Configures a TWI peripheral to operate in master mode, at the given

/// frequency (in Hz). The duty cycle of the TWI clock is set to 50%.

/// \param pTwi  Pointer to an AT91S_TWI instance.

/// \param twck  Desired TWI clock frequency.

/// \param mck  Master clock frequency.

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

void TWI_Configure(AT91S_TWI *pTwi, unsigned int twck, unsigned int mck)

{

    unsigned int ckdiv = 0;

    unsigned int cldiv;

    unsigned char ok = 0;

    trace_LOG(trace_DEBUG, "-D- TWI_Configure()\n\r");

    SANITY_CHECK(pTwi);

    // Reset the TWI

    pTwi->TWI_CR = AT91C_TWI_SWRST;

    // Set master mode

    pTwi->TWI_CR = AT91C_TWI_MSEN;

    // Configure clock

    while (!ok) {

        cldiv = ((mck / (2 * twck)) - 3) / power(2, ckdiv);

        if (cldiv <= 255) {

            ok = 1;

        }

        else {

            ckdiv++;

        }

    }

    ASSERT(ckdiv < 8, "-F- Cannot find valid TWI clock parameters\n\r");

    trace_LOG(trace_INFO, "-D- Using CKDIV = %u and CLDIV/CHDIV = %u\n\r", ckdiv, cldiv);

    pTwi->TWI_CWGR = (ckdiv << 16) | (cldiv << 8) | cldiv;

}

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

/// Sends a STOP condition on the TWI.

/// \param pTwi  Pointer to an AT91S_TWI instance.

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

void TWI_Stop(AT91S_TWI *pTwi)

{

    SANITY_CHECK(pTwi);

    pTwi->TWI_CR = AT91C_TWI_STOP;

}

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

/// Starts a read operation on the TWI bus with the specified slave, and returns

/// immediately. Data must then be read using TWI_ReadByte() whenever a byte is

/// available (poll using TWI_ByteReceived()).

/// \param pTwi  Pointer to an AT91S_TWI instance.

/// \param address  Slave address on the bus.

/// \param iaddress  Optional internal address bytes.

/// \param isize  Number of internal address bytes.

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

void TWI_StartRead(

    AT91S_TWI *pTwi,

    unsigned char address,

    unsigned int iaddress,

    unsigned char isize)

{

    trace_LOG(trace_DEBUG, "-D- TWI_StartRead()\n\r");

    SANITY_CHECK(pTwi);

    SANITY_CHECK((address & 0x80) == 0);

    SANITY_CHECK((iaddress & 0xFF000000) == 0);

    SANITY_CHECK(isize < 4);

    // Set slave address and number of internal address bytes

    pTwi->TWI_MMR = (isize << 8) | AT91C_TWI_MREAD | (address << 16);

    // Set internal address bytes

    pTwi->TWI_IADR = iaddress;

    // Send START condition

    pTwi->TWI_CR = AT91C_TWI_START;

}

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

/// Reads a byte from the TWI bus. The read operation must have been started

/// using TWI_StartRead() and a byte must be available (check with

/// TWI_ByteReceived()).

/// Returns the byte read.

/// \param pTwi  Pointer to an AT91S_TWI instance.

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

unsigned char TWI_ReadByte(AT91S_TWI *pTwi)

{

    SANITY_CHECK(pTwi);

    return pTwi->TWI_RHR;

}

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

/// Sends a byte of data to one of the TWI slaves on the bus. This function

/// must be called once before TWI_StartWrite() with the first byte of data

/// to send, then it shall be called repeatedly after that to send the

/// remaining bytes.

/// \param pTwi  Pointer to an AT91S_TWI instance.

/// \param byte  Byte to send.

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

void TWI_WriteByte(AT91S_TWI *pTwi, unsigned char byte)

{

    SANITY_CHECK(pTwi);

    pTwi->TWI_THR = byte;

}

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

/// Starts a write operation on the TWI to access the selected slave, then

/// returns immediately. A byte of data must be provided to start the write;

/// other bytes are written next.

/// \param pTwi  Pointer to an AT91S_TWI instance.

/// \param address  Address of slave to acccess on the bus.

/// \param iaddress  Optional slave internal address.

/// \param isize  Number of internal address bytes.

/// \param byte  First byte to send.

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

void TWI_StartWrite(

    AT91S_TWI *pTwi,

    unsigned char address,

    unsigned int iaddress,

    unsigned char isize,

    unsigned char byte)

{

    trace_LOG(trace_DEBUG, "-D- TWI_StartWrite()\n\r");

    SANITY_CHECK(pTwi);

    SANITY_CHECK((address & 0x80) == 0);

    SANITY_CHECK((iaddress & 0xFF000000) == 0);

    SANITY_CHECK(isize < 4);

    // Set slave address and number of internal address bytes

    pTwi->TWI_MMR = (isize << 8) | (address << 16);

    // Set internal address bytes

    pTwi->TWI_IADR = iaddress;

    // Write first byte to send

    TWI_WriteByte(pTwi, byte);

}

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

/// Returns 1 if a byte has been received and can be read on the given TWI

/// peripheral; otherwise, returns 0. This function resets the status register

/// of the TWI.

/// \param pTwi  Pointer to an AT91S_TWI instance.

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

unsigned char TWI_ByteReceived(AT91S_TWI *pTwi)

{

    return ((pTwi->TWI_SR & AT91C_TWI_RXRDY) == AT91C_TWI_RXRDY);

}

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

/// Returns 1 if a byte has been sent, so another one can be stored for

/// transmission; otherwise returns 0. This function clears the status register

/// of the TWI.

/// \param pTwi  Pointer to an AT91S_TWI instance.

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

unsigned char TWI_ByteSent(AT91S_TWI *pTwi)

{

    return ((pTwi->TWI_SR & AT91C_TWI_TXRDY) == AT91C_TWI_TXRDY);

}

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

/// Returns 1 if the current transmission is complete (the STOP has been sent);

/// otherwise returns 0.

/// \param pTwi  Pointer to an AT91S_TWI instance.

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

unsigned char TWI_TransferComplete(AT91S_TWI *pTwi)

{

    return ((pTwi->TWI_SR & AT91C_TWI_TXCOMP) == AT91C_TWI_TXCOMP);

}

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

/// Enables the selected interrupts sources on a TWI peripheral.

/// \param pTwi  Pointer to an AT91S_TWI instance.

/// \param sources  Bitwise OR of selected interrupt sources.

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

void TWI_EnableIt(AT91S_TWI *pTwi, unsigned int sources)

{

    SANITY_CHECK(pTwi);

    SANITY_CHECK((sources & 0xFFFFFEF8) == 0);

    pTwi->TWI_IER = sources;

}

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

/// Disables the selected interrupts sources on a TWI peripheral.

/// \param pTwi  Pointer to an AT91S_TWI instance.

/// \param sources  Bitwise OR of selected interrupt sources.

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

void TWI_DisableIt(AT91S_TWI *pTwi, unsigned int sources)

{

    SANITY_CHECK(pTwi);

    SANITY_CHECK((sources & 0xFFFFFEF8) == 0);

    pTwi->TWI_IDR = sources;

}

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

/// Returns the current status register of the given TWI peripheral. This

/// resets the internal value of the status register, so further read may yield

/// different values.

/// \param pTwi  Pointer to an AT91S_TWI instance.

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

unsigned int TWI_GetStatus(AT91S_TWI *pTwi)

{

    SANITY_CHECK(pTwi);

    return pTwi->TWI_SR;

}

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

/// Returns the current status register of the given TWI peripheral, but

/// masking interrupt sources which are not currently enabled.

/// This resets the internal value of the status register, so further read may

/// yield different values.

/// \param pTwi  Pointer to an AT91S_TWI instance.

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

unsigned int TWI_GetMaskedStatus(AT91S_TWI *pTwi)

{

    unsigned int status;

    SANITY_CHECK(pTwi);

    status = pTwi->TWI_SR;

    status &= pTwi->TWI_IMR;

    return status;

}