/* ----------------------------------------------------------------------------
 *         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 "ac97c.h"
#include <board.h>
#include <aic/aic.h>
#include <utility/assert.h>
#include <utility/trace.h>
#include <utility/math.h>

//------------------------------------------------------------------------------
//         Local constants
//------------------------------------------------------------------------------

/// Maximum size of one PDC buffer (in bytes).
#define MAX_PDC_COUNTER	65535

//------------------------------------------------------------------------------
//         Local types
//------------------------------------------------------------------------------

//------------------------------------------------------------------------------
/// AC97 transfer descriptor. Tracks the status and parameters of a transfer
/// on the AC97 bus.
//------------------------------------------------------------------------------
typedef struct _Ac97Transfer {

	/// Buffer containing the slots to send.
	unsigned char *pBuffer;
	/// Total number of samples to send.
	volatile unsigned int numSamples;
	/// Optional callback function.
	Ac97Callback callback;
	/// Optional argument to the callback function.
	void *pArg;

} Ac97Transfer;

//------------------------------------------------------------------------------
/// AC97 controller driver structure. Monitors the status of transfers on all
/// AC97 channels.
//------------------------------------------------------------------------------
typedef struct _Ac97c {

    /// List of transfers occuring on each channel.
	Ac97Transfer transfers[5];
} Ac97c;

//------------------------------------------------------------------------------
//         Local variables
//------------------------------------------------------------------------------

/// Global AC97 controller instance.
static Ac97c ac97c;

//------------------------------------------------------------------------------
//         Local functions
//------------------------------------------------------------------------------

//------------------------------------------------------------------------------
/// Returns the size of one sample (in bytes) on the given channel.
/// \param channel  Channel number.
//------------------------------------------------------------------------------
static unsigned char GetSampleSize(unsigned char channel)
{
    unsigned int size = 0;

    SANITY_CHECK((channel == AC97C_CHANNEL_A)
                 || (channel == AC97C_CHANNEL_B)
                 || (channel == AC97C_CHANNEL_CODEC));

    // Check selected channel
    switch (channel) {
        case AC97C_CHANNEL_CODEC: return 2;
        case AC97C_CHANNEL_A: size = (AT91C_BASE_AC97C->AC97C_CAMR & AT91C_AC97C_SIZE) >> 16; break;
        case AC97C_CHANNEL_B: size = (AT91C_BASE_AC97C->AC97C_CBMR & AT91C_AC97C_SIZE) >> 16; break;
    }

    // Compute size in bytes given SIZE field
    if ((size & 2) != 0) {

        return 2;
    }
    else {

        return 4;
    }
}

//------------------------------------------------------------------------------
/// Interrupt service routine for Codec, is invoked by AC97C_Handler.
//------------------------------------------------------------------------------
static void CodecHandler(void)
{
    unsigned int status;
    unsigned int data;
    Ac97Transfer *pTransfer = &(ac97c.transfers[AC97C_CODEC_TRANSFER]);

    // Read CODEC status register
    status = AT91C_BASE_AC97C->AC97C_COSR;
    status &= AT91C_BASE_AC97C->AC97C_COMR;

    // A sample has been transmitted
    if (status & AT91C_AC97C_TXRDY) {

        pTransfer->numSamples--;

        // If there are remaining samples, transmit one
        if (pTransfer->numSamples > 0) {

            data = *((unsigned int *) pTransfer->pBuffer);
            AT91C_BASE_AC97C->AC97C_COMR &= ~(AT91C_AC97C_TXRDY);
            AT91C_BASE_AC97C->AC97C_COTHR = data;

            // Check if transfer is read or write
            if ((data & AT91C_AC97C_READ) != 0) {
    
                AT91C_BASE_AC97C->AC97C_COMR |= AT91C_AC97C_RXRDY;
            }
            else {
            
                pTransfer->pBuffer += sizeof(unsigned int);
                AT91C_BASE_AC97C->AC97C_COMR |= AT91C_AC97C_TXRDY;
            }
        }
        // Transfer finished
        else {

            AT91C_BASE_AC97C->AC97C_IDR = AT91C_AC97C_COEVT;
            AT91C_BASE_AC97C->AC97C_COMR &= ~(AT91C_AC97C_TXRDY);
            if (pTransfer->callback) {

                pTransfer->callback(pTransfer->pArg, 0, 0);
            }
        }   
    }

    // A sample has been received
    if (status & AT91C_AC97C_RXRDY) {

        // Store sample
        data = AT91C_BASE_AC97C->AC97C_CORHR;
        *((unsigned int *) pTransfer->pBuffer) = data;

        pTransfer->pBuffer += sizeof(unsigned int);
        pTransfer->numSamples--;

        // Transfer finished
        if (pTransfer->numSamples > 0) {

            data = *((unsigned int *) pTransfer->pBuffer);
            AT91C_BASE_AC97C->AC97C_COMR &= ~(AT91C_AC97C_RXRDY);
            AT91C_BASE_AC97C->AC97C_COTHR = data;

            // Check if transfer is read or write
            if ((data & AT91C_AC97C_READ) != 0) {
    
                AT91C_BASE_AC97C->AC97C_COMR |= AT91C_AC97C_RXRDY;
            }
            else {
            
                pTransfer->pBuffer += sizeof(unsigned int);
                AT91C_BASE_AC97C->AC97C_COMR |= AT91C_AC97C_TXRDY;
            }
        }
        else {

            AT91C_BASE_AC97C->AC97C_IDR = AT91C_AC97C_COEVT;
            AT91C_BASE_AC97C->AC97C_COMR &= ~(AT91C_AC97C_RXRDY);
            if (pTransfer->callback) {

                pTransfer->callback(pTransfer->pArg, 0, 0);
            }
        }
    }
}

//------------------------------------------------------------------------------
/// Interrupt service routine for channel A, is invoked by AC97C_Handler.
//------------------------------------------------------------------------------
static void ChannelAHandler(void)
{
    unsigned int status;
    Ac97Transfer *pTransmit = &(ac97c.transfers[AC97C_CHANNEL_A_TRANSMIT]);
    Ac97Transfer *pReceive = &(ac97c.transfers[AC97C_CHANNEL_A_RECEIVE]);

    // Read channel A status register
    status = AT91C_BASE_AC97C->AC97C_CASR;

    // A buffer has been transmitted
    if ((status & AT91C_AC97C_ENDTX) != 0) {

        // Update transfer information
        if (pTransmit->numSamples > MAX_PDC_COUNTER) {

            pTransmit->numSamples -= MAX_PDC_COUNTER;
        }
        else {

            pTransmit->numSamples = 0;
        }

        // Transmit new buffers if necessary
        if (pTransmit->numSamples > MAX_PDC_COUNTER) {

            // Fill next PDC
            AT91C_BASE_AC97C->AC97C_TNPR = (unsigned int) pTransmit->pBuffer;
            if (pTransmit->numSamples > 2 * MAX_PDC_COUNTER) {

                AT91C_BASE_AC97C->AC97C_TNCR = MAX_PDC_COUNTER;
                pTransmit->pBuffer += MAX_PDC_COUNTER * GetSampleSize(AC97C_CHANNEL_A);
            }
            else {

                AT91C_BASE_AC97C->AC97C_TNCR = pTransmit->numSamples - MAX_PDC_COUNTER;
            }
        }
        // Only one buffer remaining
        else {

            AT91C_BASE_AC97C->AC97C_CAMR &= ~AT91C_AC97C_ENDTX;
            AT91C_BASE_AC97C->AC97C_CAMR |= AT91C_AC97C_TXBUFE;
        }
    }

    // Transmit completed
    if ((status & AT91C_AC97C_TXBUFE) != 0) {

        pTransmit->numSamples = 0;
        AT91C_BASE_AC97C->AC97C_PTCR = AT91C_PDC_TXTDIS;
        AT91C_BASE_AC97C->AC97C_CAMR &= ~AT91C_AC97C_TXBUFE;
        if (pTransmit->callback) {

            pTransmit->callback(pTransmit->pArg, 0, 0);
        }
    }

    // A buffer has been received
    if (status & AT91C_AC97C_ENDRX) {

        if (pReceive->numSamples > MAX_PDC_COUNTER) {
        
            pReceive->numSamples -= MAX_PDC_COUNTER;
        }
        else {

            pReceive->numSamples = 0;
        }

        // Transfer remaining samples
        if (pReceive->numSamples > MAX_PDC_COUNTER) {

            AT91C_BASE_AC97C->AC97C_RNPR = (unsigned int) pReceive->pBuffer;
            if (pReceive->numSamples > 2 * MAX_PDC_COUNTER) {
            
                AT91C_BASE_AC97C->AC97C_RNCR = MAX_PDC_COUNTER;
                pReceive->pBuffer += MAX_PDC_COUNTER * GetSampleSize(AC97C_CHANNEL_A);
            }
            else {

                AT91C_BASE_AC97C->AC97C_RNCR = pReceive->numSamples - MAX_PDC_COUNTER;
            }
        }
        // Only one buffer remaining
        else {

            AT91C_BASE_AC97C->AC97C_CAMR &= ~(AT91C_AC97C_ENDRX);
            AT91C_BASE_AC97C->AC97C_CAMR |= AT91C_AC97C_RXBUFF;
        }
    }

    // Receive complete
    if ((status & AT91C_AC97C_RXBUFF) != 0) {

        pReceive->numSamples = 0;
        AT91C_BASE_AC97C->AC97C_PTCR = AT91C_PDC_RXTDIS;
        AT91C_BASE_AC97C->AC97C_CAMR &= ~AT91C_AC97C_RXBUFF;
        if (pReceive->callback) {

            pReceive->callback(pReceive->pArg, 0, 0);
        }
    }
}

//------------------------------------------------------------------------------
//         Exported functions
//------------------------------------------------------------------------------
//------------------------------------------------------------------------------
/// This handler function must be called by the AC97C interrupt service routine.
/// Identifies which event was activated and calls the associated function.
//------------------------------------------------------------------------------ 
void AC97C_Handler(void)
{
    unsigned int status;

    // Get the real interrupt source
    status = AT91C_BASE_AC97C->AC97C_SR;
    status &= AT91C_BASE_AC97C->AC97C_IMR;
    
    // Check if an event on the codec channel is active
    if ((status & AT91C_AC97C_COEVT) != 0) {

        CodecHandler();    
    }
    // Check if an event on channel A is active
    if ((status & AT91C_AC97C_CAEVT) != 0) {

        ChannelAHandler();  
    }
}