[intelxl] Allow for arbitrary placement of ring tail registers

The virtual function transmit and receive ring tail register offsets
do not match those of the physical function.  Allow the tail register
offsets to be specified separately.

Signed-off-by: Michael Brown <mcb30@ipxe.org>

src/drivers/net/intelxl.c

  */
 static int intelxl_create_ring ( struct intelxl_nic *intelxl,
 				 struct intelxl_ring *ring ) {
-	void *ring_regs = ( intelxl->regs + ring->reg );
 	physaddr_t address;
 	int rc;
 
 	memset ( ring->desc.raw, 0, ring->len );
 
 	/* Reset tail pointer */
-	writel ( 0, ( ring_regs + INTELXL_QXX_TAIL ) );
+	writel ( 0, ( intelxl->regs + ring->tail ) );
 
 	/* Program queue context */
 	address = virt_to_bus ( ring->desc.raw );
 	ring->cons = 0;
 
 	DBGC ( intelxl, "INTELXL %p ring %06x is at [%08llx,%08llx)\n",
-	       intelxl, ring->reg, ( ( unsigned long long ) address ),
+	       intelxl, ( ring->reg + ring->tail ),
+	       ( ( unsigned long long ) address ),
 	       ( ( unsigned long long ) address + ring->len ) );
 
 	return 0;
 	if ( refilled ) {
 		wmb();
 		rx_tail = ( intelxl->rx.prod % INTELXL_RX_NUM_DESC );
-		writel ( rx_tail,
-			 ( intelxl->regs + intelxl->rx.reg + INTELXL_QXX_TAIL));
+		writel ( rx_tail, ( intelxl->regs + intelxl->rx.tail ) );
 	}
 }
 
 	wmb();
 
 	/* Notify card that there are packets ready to transmit */
-	writel ( tx_tail,
-		 ( intelxl->regs + intelxl->tx.reg + INTELXL_QXX_TAIL ) );
+	writel ( tx_tail, ( intelxl->regs + intelxl->tx.tail ) );
 
 	DBGC2 ( intelxl, "INTELXL %p TX %d is [%llx,%llx)\n", intelxl, tx_idx,
 		( ( unsigned long long ) address ),
 
 	/* Configure queue register addresses */
 	intelxl->tx.reg = INTELXL_QTX ( intelxl->queue );
+	intelxl->tx.tail = ( intelxl->tx.reg + INTELXL_QXX_TAIL );
 	intelxl->rx.reg = INTELXL_QRX ( intelxl->queue );
+	intelxl->rx.tail = ( intelxl->rx.reg + INTELXL_QXX_TAIL );
 
 	/* Configure interrupt causes */
 	writel ( ( INTELXL_QINT_TQCTL_NEXTQ_INDX_NONE |

src/drivers/net/intelxl.h

 
 	/** Register block */
 	unsigned int reg;
+	/** Tail register */
+	unsigned int tail;
 	/** Length (in bytes) */
 	size_t len;
 	/** Program queue context