RX_FRAME_PORT
status = ioread16(lp->virt_addr + RX_FRAME_PORT);
length = ioread16(lp->virt_addr + RX_FRAME_PORT);
readwords(lp, RX_FRAME_PORT, skb_put(skb, length), length >> 1);
skb->data[length-1] = ioread16(lp->virt_addr + RX_FRAME_PORT);
#define TX_FRAME_PORT RX_FRAME_PORT