ethread.c

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/* ethread.c - ethread */

#include <xinu.h>

/*------------------------------------------------------------------------
 * ethread - read an incoming packet on TI AM335X Ethernet
 *------------------------------------------------------------------------
 */
int32   ethread (
        struct  dentry *devptr,
        void    *buf,
        uint32  count
    )
{
    struct  ethcblk *ethptr;    /* Ethernet ctl blk ptr */
    struct  eth_a_csreg *csrptr;    /* Ethernet CSR pointer */
    struct  eth_a_rx_desc *rdescptr;/* Rx Desc. pointer */
    struct  eth_a_rx_desc *prev;    /* Prev Rx desc pointer */
    uint32  retval;         /* Num of bytes returned*/

    ethptr = &ethertab[devptr->dvminor];

    /* Get the pointer to Ethernet CSR */
    csrptr = (struct eth_a_csreg *)ethptr->csr;

    /* Wait for a packet */
    wait(ethptr->isem);

    /* Get pointer to the descriptor */
    rdescptr = (struct eth_a_rx_desc *)ethptr->rxRing +
                        ethptr->rxHead;

    /* Read the packet length */
    retval = rdescptr->packlen;
    if(retval > count) {
        retval = count;
    }

    /* Copy the packet into user provided buffer */
    memcpy((char *)buf, (char *)rdescptr->buffer, retval);

    /* Initialize the descriptor for next packet */
    rdescptr->stat = ETH_AM335X_RDS_OWN;
    rdescptr->bufoff = 0;
    rdescptr->buflen = ETH_BUF_SIZE;
    rdescptr->packlen = 0;
    rdescptr->next = NULL;

    /* Insert the descriptor into Rx queue */
    prev = (struct eth_a_rx_desc *)csrptr->stateram->rx_hdp[0];
    if(prev == NULL) {
        kprintf("hdp 0, adding %x\n", rdescptr);
        csrptr->stateram->rx_hdp[0] = (uint32)rdescptr;
    }
    else {
        while(prev->next != NULL) {
            prev = prev->next;
        }
        prev->next = rdescptr;
    }

    /* Increment the head index of rx ring */
    ethptr->rxHead++;
    if(ethptr->rxHead >= ethptr->rxRingSize) {
        ethptr->rxHead = 0;
    }

    return retval;
}