MakefileBasedBuild/Atmel/sam3x/sam3x-ek/libraries/libchip_sam3x/source/spi.c

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/** \addtogroup spi_module Working with SPI
 * The SPI driver provides the interface to configure and use the SPI
 * peripheral.
 *
 * The Serial Peripheral Interface (SPI) circuit is a synchronous serial
 * data link that provides communication with external devices in Master
 * or Slave Mode.
 *
 * To use the SPI, the user has to follow these few steps:
 * -# Enable the SPI pins required by the application (see pio.h).
 * -# Configure the SPI using the \ref SPI_Configure(). This enables the
 *    peripheral clock. The mode register is loaded with the given value.
 * -# Configure all the necessary chip selects with \ref SPI_ConfigureNPCS().
 * -# Enable the SPI by calling \ref SPI_Enable().
 * -# Send/receive data using \ref SPI_Write() and \ref SPI_Read(). Note that 
\ref SPI_Read()
 *    must be called after \ref SPI_Write() to retrieve the last value read.
 * -# Send/receive data using the PDC with the \ref SPI_WriteBuffer() and
 *    \ref SPI_ReadBuffer() functions.
 * -# Disable the SPI by calling \ref SPI_Disable().
 *
 * For more accurate information, please look at the SPI section of the
 * Datasheet.
 *
 * Related files :\n
 * \ref spi.c\n
 * \ref spi.h.\n
*/
/*@{*/
/*@}*/

/**
 * \file
 *
 * Implementation of Serial Peripheral Interface (SPI) controller.
 *
 */

/*----------------------------------------------------------------------------
 *        Headers
 *----------------------------------------------------------------------------*/

#include "chip.h"

#include <stdint.h>

/*----------------------------------------------------------------------------
 *        Exported functions
 *----------------------------------------------------------------------------*/

/**
 * \brief Enables a SPI peripheral.
 *
 * \param spi  Pointer to an Spi instance.
 */
extern void SPI_Enable( Spi* spi )
{
    spi->SPI_CR = SPI_CR_SPIEN ;
}

/**
 * \brief Disables a SPI peripheral.
 *
 * \param spi  Pointer to an Spi instance.
 */
extern void SPI_Disable( Spi* spi )
{
    spi->SPI_CR = SPI_CR_SPIDIS ;
}

/**
 * \brief Enables one or more interrupt sources of a SPI peripheral.
 *
 * \param spi  Pointer to an Spi instance.
 * \param sources Bitwise OR of selected interrupt sources.
 */
extern void SPI_EnableIt( Spi* spi, uint32_t dwSources )
{
    spi->SPI_IER = dwSources ;
}

/**
 * \brief Disables one or more interrupt sources of a SPI peripheral.
 *
 * \param spi  Pointer to an Spi instance.
 * \param sources Bitwise OR of selected interrupt sources.
 */
extern void SPI_DisableIt( Spi* spi, uint32_t dwSources )
{
    spi->SPI_IDR = dwSources ;
}

/**
 * \brief Configures a SPI peripheral as specified. The configuration can be computed
 * using several macros (see \ref spi_configuration_macros).
 *
 * \param spi  Pointer to an Spi instance.
 * \param id   Peripheral ID of the SPI.
 * \param configuration  Value of the SPI configuration register.
 */
extern void SPI_Configure( Spi* spi, uint32_t dwId, uint32_t dwConfiguration )
{
    PMC_EnablePeripheral( dwId ) ;
    spi->SPI_CR = SPI_CR_SPIDIS ;

    /* Execute a software reset of the SPI twice */
    spi->SPI_CR = SPI_CR_SWRST ;
    spi->SPI_CR = SPI_CR_SWRST ;
    spi->SPI_MR = dwConfiguration ;
}

/**
 * \brief Configures SPI chip select.
 *
 * \param spi  Pointer to an Spi instance.
 * \param cS  Chip select of NPSCx.
 */
extern void SPI_ChipSelect( Spi* spi, uint8_t cS)
{
    spi->SPI_MR |= SPI_MR_PCS_Msk ;
    spi->SPI_MR &= ~(SPI_MR_PCS ( cS )) ;
}

/**
 * \brief Configures SPI Mode Register.
 *
 * \param spi  Pointer to an Spi instance.
 * \param configuration  Value of the SPI mode register.
 */
extern void SPI_SetMode( Spi* spi, 
                         uint32_t dwConfiguration )
{
    spi->SPI_MR = dwConfiguration ;
}

/**
 * \brief Configures SPI to release last used CS line.
 *
 * \param spi  Pointer to an Spi instance.
 */
extern void SPI_ReleaseCS( Spi* spi )
{
    spi->SPI_CR = SPI_CR_LASTXFER ;
}


/**
 * \brief Configures a chip select of a SPI peripheral. The chip select configuration
 * is computed using several macros (see \ref spi_configuration_macros).
 *
 * \param spi   Pointer to an Spi instance.
 * \param npcs  Chip select to configure (0, 1, 2 or 3).
 * \param configuration  Desired chip select configuration.
 */
void SPI_ConfigureNPCS( Spi* spi, uint32_t dwNpcs, uint32_t dwConfiguration )
{
    spi->SPI_CSR[dwNpcs] = dwConfiguration ;
}

/**
 * \brief Configures a chip select active mode of a SPI peripheral.
 *
 * \param spi   Pointer to an Spi instance.
 * \param dwNpcs  Chip select to configure (0, 1, 2 or 3).
 * \param bReleaseOnLast CS controlled by last transfer.
 *                       SPI_ReleaseCS() is used to deactive CS. 
 */
void SPI_ConfigureCSMode( Spi* spi, uint32_t dwNpcs, uint32_t bReleaseOnLast )
{
    if (bReleaseOnLast)
    {
        spi->SPI_CSR[dwNpcs] |=  SPI_CSR_CSAAT;
    }
    else
    {
        spi->SPI_CSR[dwNpcs] &= ~SPI_CSR_CSAAT;
    }
}

/**
 * \brief Get the current status register of the given SPI peripheral.
 * \note This resets the internal value of the status register, so further
 * read may yield different values.
 * \param spi   Pointer to a Spi instance.
 * \return  SPI status register.
 */
extern uint32_t SPI_GetStatus( Spi* spi )
{
    return spi->SPI_SR ;
}

/**
 * \brief Reads and returns the last word of data received by a SPI peripheral. This
 * method must be called after a successful SPI_Write call.
 *
 * \param spi  Pointer to an Spi instance.
 *
 * \return readed data.
 */
extern uint32_t SPI_Read( Spi* spi )
{
    while ( (spi->SPI_SR & SPI_SR_RDRF) == 0 ) ;

    return spi->SPI_RDR & 0xFFFF ;
}

/**
 * \brief Sends data through a SPI peripheral. If the SPI is configured to use a fixed
 * peripheral select, the npcs value is meaningless. Otherwise, it identifies
 * the component which shall be addressed.
 *
 * \param spi   Pointer to an Spi instance.
 * \param npcs  Chip select of the component to address (0, 1, 2 or 3).
 * \param data  Word of data to send.
 */
extern void SPI_Write( Spi* spi, uint32_t dwNpcs, uint16_t wData )
{
    /* Send data */
    while ( (spi->SPI_SR & SPI_SR_TXEMPTY) == 0 ) ;
    spi->SPI_TDR = wData | SPI_PCS( dwNpcs ) ;
    while ( (spi->SPI_SR & SPI_SR_TDRE) == 0 ) ;
}

/**
 * \brief Sends last data through a SPI peripheral.
 * If the SPI is configured to use a fixed peripheral select, the npcs value is
 * meaningless. Otherwise, it identifies the component which shall be addressed.
 *
 * \param spi   Pointer to an Spi instance.
 * \param npcs  Chip select of the component to address (0, 1, 2 or 3).
 * \param data  Word of data to send.
 */
extern void SPI_WriteLast( Spi* spi, uint32_t dwNpcs, uint16_t wData )
{
    /* Send data */
    while ( (spi->SPI_SR & SPI_SR_TXEMPTY) == 0 ) ;
    spi->SPI_TDR = wData | SPI_PCS( dwNpcs ) | SPI_TDR_LASTXFER ;
    while ( (spi->SPI_SR & SPI_SR_TDRE) == 0 ) ;
}

/**
 * \brief Check if SPI transfer finish.
 *
 * \param spi  Pointer to an Spi instance.
 *
 * \return Returns 1 if there is no pending write operation on the SPI; otherwise
 * returns 0.
 */
extern uint32_t SPI_IsFinished( Spi* spi )
{
    return ((spi->SPI_SR & SPI_SR_TXEMPTY) != 0) ;
}