net: ll_temac: Fix support for 64-bit platforms

The use of buffer descriptor APP4 field (32-bit) for storing skb pointer
obviously does not work on 64-bit platforms.
As APP3 is also unused, we can use that to store the other half of 64-bit
pointer values.

Contrary to what is hinted at in commit message of commit 15bfe05c
("net: ethernet: xilinx: Mark XILINX_LL_TEMAC broken on 64-bit")
there are no other pointers stored in cdmac_bd.
Signed-off-by: Esben Haabendal <esben@geanix.com>
Reviewed-by: Andrew Lunn <andrew@lunn.ch>
Signed-off-by: David S. Miller <davem@davemloft.net>

drivers/net/ethernet/xilinx/Kconfig

@@ -34,7 +34,6 @@ config XILINX_AXI_EMAC
 config XILINX_LL_TEMAC
 	tristate "Xilinx LL TEMAC (LocalLink Tri-mode Ethernet MAC) driver"
 	depends on (PPC || MICROBLAZE)
-	depends on !64BIT || BROKEN
 	select PHYLIB
 	---help---
 	  This driver supports the Xilinx 10/100/1000 LocalLink TEMAC

drivers/net/ethernet/xilinx/ll_temac_main.c

@@ -619,11 +619,39 @@ static void temac_adjust_link(struct net_device *ndev)
 	mutex_unlock(&lp->indirect_mutex);
 }
 
+#ifdef CONFIG_64BIT
+
+void ptr_to_txbd(void *p, struct cdmac_bd *bd)
+{
+	bd->app3 = (u32)(((u64)p) >> 32);
+	bd->app4 = (u32)((u64)p & 0xFFFFFFFF);
+}
+
+void *ptr_from_txbd(struct cdmac_bd *bd)
+{
+	return (void *)(((u64)(bd->app3) << 32) | bd->app4);
+}
+
+#else
+
+void ptr_to_txbd(void *p, struct cmdac_bd *bd)
+{
+	bd->app4 = (u32)p;
+}
+
+void *ptr_from_txbd(struct cdmac_bd *bd)
+{
+	return (void *)(bd->app4);
+}
+
+#endif
+
 static void temac_start_xmit_done(struct net_device *ndev)
 {
 	struct temac_local *lp = netdev_priv(ndev);
 	struct cdmac_bd *cur_p;
 	unsigned int stat = 0;
+	struct sk_buff *skb;
 
 	cur_p = &lp->tx_bd_v[lp->tx_bd_ci];
 	stat = cur_p->app0;
@@ -631,8 +659,9 @@ static void temac_start_xmit_done(struct net_device *ndev)
 	while (stat & STS_CTRL_APP0_CMPLT) {
 		dma_unmap_single(ndev->dev.parent, cur_p->phys, cur_p->len,
 				 DMA_TO_DEVICE);
-		if (cur_p->app4)
-			dev_consume_skb_irq((struct sk_buff *)cur_p->app4);
+		skb = (struct sk_buff *)ptr_from_txbd(cur_p);
+		if (skb)
+			dev_consume_skb_irq(skb);
 		cur_p->app0 = 0;
 		cur_p->app1 = 0;
 		cur_p->app2 = 0;
@@ -711,7 +740,7 @@ temac_start_xmit(struct sk_buff *skb, struct net_device *ndev)
 	cur_p->len = skb_headlen(skb);
 	cur_p->phys = dma_map_single(ndev->dev.parent, skb->data,
 				     skb_headlen(skb), DMA_TO_DEVICE);
-	cur_p->app4 = (unsigned long)skb;
+	ptr_to_txbd((void *)skb, cur_p);
 
 	for (ii = 0; ii < num_frag; ii++) {
 		lp->tx_bd_tail++;