davinci_emac: use internal addresses in buffer descriptors

On AM35xx CPPI RAM had different addresses when accessed from the CPU
and from the EMAC. We need to account this to deal with the buffer
descriptors correctly.

Signed-off-by: Ilya Yanok <yanok@emcraft.com>
diff --git a/drivers/net/davinci_emac.c b/drivers/net/davinci_emac.c
index 43c4373..2ac6874 100644
--- a/drivers/net/davinci_emac.c
+++ b/drivers/net/davinci_emac.c
@@ -48,6 +48,27 @@
 unsigned int	emac_dbg = 0;
 #define debug_emac(fmt,args...)	if (emac_dbg) printf(fmt,##args)
 
+#ifdef EMAC_HW_RAM_ADDR
+static inline unsigned long BD_TO_HW(unsigned long x)
+{
+	if (x == 0)
+		return 0;
+
+	return x - EMAC_WRAPPER_RAM_ADDR + EMAC_HW_RAM_ADDR;
+}
+
+static inline unsigned long HW_TO_BD(unsigned long x)
+{
+	if (x == 0)
+		return 0;
+
+	return x - EMAC_HW_RAM_ADDR + EMAC_WRAPPER_RAM_ADDR;
+}
+#else
+#define BD_TO_HW(x)	(x)
+#define HW_TO_BD(x)	(x)
+#endif
+
 #ifdef DAVINCI_EMAC_GIG_ENABLE
 #define emac_gigabit_enable(phy_addr)	davinci_eth_gigabit_enable(phy_addr)
 #else
@@ -448,7 +469,7 @@
 	/* Create RX queue and set receive process in place */
 	emac_rx_active_head = emac_rx_desc;
 	for (cnt = 0; cnt < EMAC_MAX_RX_BUFFERS; cnt++) {
-		rx_desc->next = (u_int32_t)(rx_desc + 1);
+		rx_desc->next = BD_TO_HW((u_int32_t)(rx_desc + 1));
 		rx_desc->buffer = &emac_rx_buffers[cnt * (EMAC_MAX_ETHERNET_PKT_SIZE + EMAC_PKT_ALIGN)];
 		rx_desc->buff_off_len = EMAC_MAX_ETHERNET_PKT_SIZE;
 		rx_desc->pkt_flag_len = EMAC_CPPI_OWNERSHIP_BIT;
@@ -501,7 +522,7 @@
 	emac_gigabit_enable(active_phy_addr[index]);
 
 	/* Start receive process */
-	writel((u_int32_t)emac_rx_desc, &adap_emac->RX0HDP);
+	writel(BD_TO_HW((u_int32_t)emac_rx_desc), &adap_emac->RX0HDP);
 
 	debug_emac("- emac_open\n");
 
@@ -619,7 +640,7 @@
 				      EMAC_CPPI_OWNERSHIP_BIT |
 				      EMAC_CPPI_EOP_BIT);
 	/* Send the packet */
-	writel((unsigned long)emac_tx_desc, &adap_emac->TX0HDP);
+	writel(BD_TO_HW((unsigned long)emac_tx_desc), &adap_emac->TX0HDP);
 
 	/* Wait for packet to complete or link down */
 	while (1) {
@@ -663,14 +684,14 @@
 		}
 
 		/* Ack received packet descriptor */
-		writel((unsigned long)rx_curr_desc, &adap_emac->RX0CP);
+		writel(BD_TO_HW((ulong)rx_curr_desc), &adap_emac->RX0CP);
 		curr_desc = rx_curr_desc;
 		emac_rx_active_head =
-			(volatile emac_desc *) rx_curr_desc->next;
+			(volatile emac_desc *) (HW_TO_BD(rx_curr_desc->next));
 
 		if (status & EMAC_CPPI_EOQ_BIT) {
 			if (emac_rx_active_head) {
-				writel((unsigned long)emac_rx_active_head,
+				writel(BD_TO_HW((ulong)emac_rx_active_head),
 				       &adap_emac->RX0HDP);
 			} else {
 				emac_rx_queue_active = 0;
@@ -688,7 +709,7 @@
 			emac_rx_active_head = curr_desc;
 			emac_rx_active_tail = curr_desc;
 			if (emac_rx_queue_active != 0) {
-				writel((unsigned long)emac_rx_active_head,
+				writel(BD_TO_HW((ulong)emac_rx_active_head),
 				       &adap_emac->RX0HDP);
 				printf ("INFO: emac_rcv_pkt: active queue head = 0, HDP fired\n");
 				emac_rx_queue_active = 1;
@@ -696,10 +717,10 @@
 		} else {
 			tail_desc = emac_rx_active_tail;
 			emac_rx_active_tail = curr_desc;
-			tail_desc->next = (unsigned int) curr_desc;
+			tail_desc->next = BD_TO_HW((ulong) curr_desc);
 			status = tail_desc->pkt_flag_len;
 			if (status & EMAC_CPPI_EOQ_BIT) {
-				writel((unsigned long)curr_desc,
+				writel(BD_TO_HW((ulong)curr_desc),
 				       &adap_emac->RX0HDP);
 				status &= ~EMAC_CPPI_EOQ_BIT;
 				tail_desc->pkt_flag_len = status;