net: macb: Fix 64 bit addressing support for GEM

This patch adds support for 32 bit GEM in
64 bit system. It checks capability at runtime
and uses appropriate buffer descriptor.

Signed-off-by: Rafal Ozieblo <rafalo@cadence.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

drivers/net/ethernet/cadence/macb.h

@@ -385,6 +385,8 @@
 /* Bitfields in DCFG6. */
 #define GEM_PBUF_LSO_OFFSET			27
 #define GEM_PBUF_LSO_SIZE			1
+#define GEM_DAW64_OFFSET			23
+#define GEM_DAW64_SIZE				1
 
 /* Constants for CLK */
 #define MACB_CLK_DIV8				0
@@ -487,12 +489,20 @@
 struct macb_dma_desc {
 	u32	addr;
 	u32	ctrl;
-#ifdef CONFIG_ARCH_DMA_ADDR_T_64BIT
-	u32     addrh;
-	u32     resvd;
-#endif
 };
 
+#ifdef CONFIG_ARCH_DMA_ADDR_T_64BIT
+enum macb_hw_dma_cap {
+	HW_DMA_CAP_32B,
+	HW_DMA_CAP_64B,
+};
+
+struct macb_dma_desc_64 {
+	u32 addrh;
+	u32 resvd;
+};
+#endif
+
 /* DMA descriptor bitfields */
 #define MACB_RX_USED_OFFSET			0
 #define MACB_RX_USED_SIZE			1
@@ -874,6 +884,10 @@ struct macb {
 	unsigned int		jumbo_max_len;
 
 	u32			wol;
+
+#ifdef CONFIG_ARCH_DMA_ADDR_T_64BIT
+	enum macb_hw_dma_cap hw_dma_cap;
+#endif
 };
 
 static inline bool macb_is_gem(struct macb *bp)