/*
 * File:    fecbd.c
 * Purpose: Provide a simple buffer management driver
 *
 * Notes:
 */
#include <common.h>
#include <linux/types.h>

#include <mach/mcf54xx-regs.h>
#include <proc/mcdapi/MCD_dma.h>
#include <proc/net/net.h>
#include <proc/fecbd.h>
#include <proc/fec.h>
#include <proc/dma_utils.h>

#define ASSERT(x) if (!(x)) hang();

/*
 * This implements a simple static buffer descriptor
 * ring for each channel and each direction
 *
 * FEC Buffer Descriptors need to be aligned to a 4-byte boundary.
 * In order to accomplish this, data is over-allocated and manually
 * aligned at runtime
 *
 * Enough space is allocated for each of the two FEC channels to have
 * NRXBD Rx BDs and NTXBD Tx BDs
 *
 */
FECBD unaligned_bds[(2 * NRXBD) + (2 * NTXBD) + 1];

/*
 * These pointers are used to reference into the chunck of data set
 * aside for buffer descriptors
 */
FECBD *RxBD;
FECBD *TxBD;

/*
 * Macros to easier access to the BD ring
 */
#define RxBD(ch,i)      RxBD[(ch * NRXBD) + i]
#define TxBD(ch,i)      TxBD[(ch * NTXBD) + i]

/*
 * Buffer descriptor indexes
 */
static int iTxbd_new;
static int iTxbd_old;
static int iRxbd;

/*
 * Initialize the FEC Buffer Descriptor ring
 * Buffer Descriptor format is defined by the MCDAPI
 *
 * Parameters:
 *  ch      FEC channel
 */
void
fecbd_init(uint8_t ch)
{
    NBUF *nbuf;
    int i;

    /*
     * Align Buffer Descriptors to 4-byte boundary
     */
    RxBD = (FECBD *)(((int)unaligned_bds + 3) & 0xFFFFFFFC);
    TxBD = (FECBD *)((int)RxBD + (sizeof(FECBD) * 2 * NRXBD));

    /*
     * Initialize the Rx Buffer Descriptor ring
     */
    for (i = 0; i < NRXBD; ++i)
    {
        /* Grab a network buffer from the free list */
        nbuf = nbuf_alloc();
        ASSERT(nbuf);

        /* Initialize the BD */
        RxBD(ch,i).status = RX_BD_E | RX_BD_INTERRUPT;
        RxBD(ch,i).length = RX_BUF_SZ;
        RxBD(ch,i).data =  nbuf->data;

        /* Add the network buffer to the Rx queue */
        nbuf_add(NBUF_RX_RING, nbuf);
    }

    /*
     * Set the WRAP bit on the last one
     */
    RxBD(ch,i-1).status |= RX_BD_W;

    /*
     * Initialize the Tx Buffer Descriptor ring
     */
    for (i = 0; i < NTXBD; ++i)
    {
        TxBD(ch,i).status = TX_BD_INTERRUPT;
        TxBD(ch,i).length = 0;
        TxBD(ch,i).data = NULL;
    }

    /*
     * Set the WRAP bit on the last one
     */
    TxBD(ch,i-1).status |= TX_BD_W;

    /*
     * Initialize the buffer descriptor indexes
     */
    iTxbd_new = iTxbd_old = iRxbd = 0;
}

void
fecbd_dump(uint8_t ch)
{
    #ifdef CONFIG_DRIVER_NET_MCF54XX_DEBUG
    int i;

    printf("\n------------ FEC%d BDs -----------\n",ch);
    printf("RxBD Ring\n");
    for (i=0; i<NRXBD; i++)
    {
        printf("%02d: BD Addr=0x%08x, Ctrl=0x%04x, Lgth=%04d, DataPtr=0x%08x\n",
            i, &RxBD(ch,i),
            RxBD(ch,i).status,
            RxBD(ch,i).length,
            RxBD(ch,i).data);
    }
    printf("TxBD Ring\n");
    for (i=0; i<NTXBD; i++)
    {
        printf("%02d: BD Addr=0x%08x, Ctrl=0x%04x, Lgth=%04d, DataPtr=0x%08x\n",
            i, &TxBD(ch,i),
            TxBD(ch,i).status,
            TxBD(ch,i).length,
            TxBD(ch,i).data);
    }
    printf("--------------------------------\n\n");
    #endif
}

/*
 * Return the address of the first buffer descriptor in the ring.
 *
 * Parameters:
 *  ch          FEC channel
 *  direction   Rx or Tx Macro
 *
 * Return Value:
 *  The start address of the selected Buffer Descriptor ring
 */
uint32_t
fecbd_get_start(uint8_t ch, uint8_t direction)
{
    switch (direction)
    {
        case Rx:
            return (uint32_t)((int)RxBD + (ch * sizeof(FECBD) * NRXBD));
        case Tx:
        default:
            return (uint32_t)((int)TxBD + (ch * sizeof(FECBD) * NTXBD));
    }
}

FECBD *
fecbd_rx_alloc(uint8_t ch)
{
    int i = iRxbd;

    /* Check to see if the ring of BDs is full */
    if (RxBD(ch,i).status & RX_BD_E)
        return NULL;

    /* Increment the circular index */
    iRxbd = (uint8_t)((iRxbd + 1) % NRXBD);

    return &RxBD(ch,i);
}

/*
 * This function keeps track of the next available Tx BD in the ring
 *
 * Parameters:
 *  ch  FEC channel
 *
 * Return Value:
 *  Pointer to next available buffer descriptor.
 *  NULL if the BD ring is full
 */
FECBD *
fecbd_tx_alloc(uint8_t ch)
{
    int i = iTxbd_new;

    /* Check to see if the ring of BDs is full */
    if (TxBD(ch,i).status & TX_BD_R)
        return NULL;

    /* Increment the circular index */
    iTxbd_new = (uint8_t)((iTxbd_new + 1) % NTXBD);

    return &TxBD(ch,i);
}

/*
 * This function keeps track of the Tx BDs that have already been
 * processed by the FEC
 *
 * Parameters:
 *  ch  FEC channel
 *
 * Return Value:
 *  Pointer to the oldest buffer descriptor that has already been sent
 *  by the FEC, NULL if the BD ring is empty
 */
FECBD *
fecbd_tx_free(uint8_t ch)
{
    int i = iTxbd_old;

    /* Check to see if the ring of BDs is empty */
    if ((TxBD(ch,i).data == NULL) || (TxBD(ch,i).status & TX_BD_R))
        return NULL;

    /* Increment the circular index */
    iTxbd_old = (uint8_t)((iTxbd_old + 1) % NTXBD);

    return &TxBD(ch,i);
}