net/macb: add HW features to macb driver

index e9daa07..91870e9 100644
@@ -264,7 +264,8 @@ static void macb_handle_link_change(struct net_device *dev)
 				reg |= MACB_BIT(FD);
 			if (phydev->speed == SPEED_100)
 				reg |= MACB_BIT(SPD);
-			if (phydev->speed == SPEED_1000)
+			if (phydev->speed == SPEED_1000 &&
+			    bp->caps & MACB_CAPS_GIGABIT_MODE_AVAILABLE)
 				reg |= GEM_BIT(GBE);
 
 			macb_or_gem_writel(bp, NCFGR, reg);

@@ -337,7 +338,7 @@ static int macb_mii_probe(struct net_device *dev)
 	}
 
 	/* mask with MAC supported features */
-	if (macb_is_gem(bp))
+	if (macb_is_gem(bp) && bp->caps & MACB_CAPS_GIGABIT_MODE_AVAILABLE)
 		phydev->supported &= PHY_GBIT_FEATURES;
 	else
 		phydev->supported &= PHY_BASIC_FEATURES;

@@ -1342,7 +1343,7 @@ static u32 macb_dbw(struct macb *bp)
 /*
  * Configure the receive DMA engine
  * - use the correct receive buffer size
- * - set the possibility to use INCR16 bursts
+ * - set best burst length for DMA operations
  *   (if not supported by FIFO, it will fallback to default)
  * - set both rx/tx packet buffers to full memory size
  * These are configurable parameters for GEM.

@@ -1354,24 +1355,16 @@ static void macb_configure_dma(struct macb *bp)
 	if (macb_is_gem(bp)) {
 		dmacfg = gem_readl(bp, DMACFG) & ~GEM_BF(RXBS, -1L);
 		dmacfg |= GEM_BF(RXBS, bp->rx_buffer_size / RX_BUFFER_MULTIPLE);
-		dmacfg |= GEM_BF(FBLDO, 16);
+		if (bp->dma_burst_length)
+			dmacfg = GEM_BFINS(FBLDO, bp->dma_burst_length, dmacfg);
 		dmacfg |= GEM_BIT(TXPBMS) | GEM_BF(RXBMS, -1L);
 		dmacfg &= ~GEM_BIT(ENDIA);
+		netdev_dbg(bp->dev, "Cadence configure DMA with 0x%08x\n",
+			   dmacfg);
 		gem_writel(bp, DMACFG, dmacfg);
 	}
 }
 
-/*
- * Configure peripheral capacities according to integration options used
- */
-static void macb_configure_caps(struct macb *bp)
-{
-	if (macb_is_gem(bp)) {
-		if (GEM_BFEXT(IRQCOR, gem_readl(bp, DCFG1)) == 0)
-			bp->caps |= MACB_CAPS_ISR_CLEAR_ON_WRITE;
-	}
-}
-
 static void macb_init_hw(struct macb *bp)
 {
 	u32 config;

@@ -1394,7 +1387,6 @@ static void macb_init_hw(struct macb *bp)
 	bp->duplex = DUPLEX_HALF;
 
 	macb_configure_dma(bp);
-	macb_configure_caps(bp);
 
 	/* Initialize TX and RX buffers */
 	macb_writel(bp, RBQP, bp->rx_ring_dma);

@@ -1783,17 +1775,61 @@ static const struct net_device_ops macb_netdev_ops = {
 };
 
 #if defined(CONFIG_OF)
+static struct macb_config pc302gem_config = {
+	.caps = MACB_CAPS_GIGABIT_MODE_AVAILABLE,
+	.dma_burst_length = 16,
+};
+
 static const struct of_device_id macb_dt_ids[] = {
 	{ .compatible = "cdns,at32ap7000-macb" },
 	{ .compatible = "cdns,at91sam9260-macb" },
 	{ .compatible = "cdns,macb" },
-	{ .compatible = "cdns,pc302-gem" },
-	{ .compatible = "cdns,gem" },
+	{ .compatible = "cdns,pc302-gem", .data = &pc302gem_config },
+	{ .compatible = "cdns,gem", .data = &pc302gem_config },
 	{ /* sentinel */ }
 };
 MODULE_DEVICE_TABLE(of, macb_dt_ids);
 #endif
 
+/*
+ * Configure peripheral capacities according to device tree
+ * and integration options used
+ */
+static void macb_configure_caps(struct macb *bp)
+{
+	u32 dcfg;
+	const struct of_device_id *match;
+	const struct macb_config *config;
+
+	if (bp->pdev->dev.of_node) {
+		match = of_match_node(macb_dt_ids, bp->pdev->dev.of_node);
+		if (match && match->data) {
+			config = (const struct macb_config *)match->data;
+
+			bp->caps = config->caps;
+			/*
+			 * As we have access to the matching node, configure
+			 * DMA burst length as well
+			 */
+			bp->dma_burst_length = config->dma_burst_length;
+		}
+	}
+
+	if (MACB_BFEXT(IDNUM, macb_readl(bp, MID)) == 0x2)
+		bp->caps |= MACB_CAPS_MACB_IS_GEM;
+
+	if (macb_is_gem(bp)) {
+		dcfg = gem_readl(bp, DCFG1);
+		if (GEM_BFEXT(IRQCOR, dcfg) == 0)
+			bp->caps |= MACB_CAPS_ISR_CLEAR_ON_WRITE;
+		dcfg = gem_readl(bp, DCFG2);
+		if ((dcfg & (GEM_BIT(RX_PKT_BUFF) | GEM_BIT(TX_PKT_BUFF))) == 0)
+			bp->caps |= MACB_CAPS_FIFO_MODE;
+	}
+
+	netdev_dbg(bp->dev, "Cadence caps 0x%08x\n", bp->caps);
+}
+
 static int __init macb_probe(struct platform_device *pdev)
 {
 	struct macb_platform_data *pdata;

@@ -1897,6 +1933,9 @@ static int __init macb_probe(struct platform_device *pdev)
 
 	dev->base_addr = regs->start;
 
+	/* setup capacities */
+	macb_configure_caps(bp);
+
 	/* setup appropriated routines according to adapter type */
 	if (macb_is_gem(bp)) {
 		bp->macbgem_ops.mog_alloc_rx_buffers = gem_alloc_rx_buffers;

index 51c0244..7ce751b 100644
@@ -305,6 +305,12 @@
 #define GEM_DBWDEF_OFFSET			25
 #define GEM_DBWDEF_SIZE				3
 
+/* Bitfields in DCFG2. */
+#define GEM_RX_PKT_BUFF_OFFSET			20
+#define GEM_RX_PKT_BUFF_SIZE			1
+#define GEM_TX_PKT_BUFF_OFFSET			21
+#define GEM_TX_PKT_BUFF_SIZE			1
+
 /* Constants for CLK */
 #define MACB_CLK_DIV8				0
 #define MACB_CLK_DIV16				1

@@ -326,7 +332,10 @@
 #define MACB_MAN_CODE				2
 
 /* Capability mask bits */
-#define MACB_CAPS_ISR_CLEAR_ON_WRITE		0x1
+#define MACB_CAPS_ISR_CLEAR_ON_WRITE		0x00000001
+#define MACB_CAPS_FIFO_MODE			0x10000000
+#define MACB_CAPS_GIGABIT_MODE_AVAILABLE	0x20000000
+#define MACB_CAPS_MACB_IS_GEM			0x80000000
 
 /* Bit manipulation macros */
 #define MACB_BIT(name)					\

@@ -554,6 +563,11 @@ struct macb_or_gem_ops {
 	int	(*mog_rx)(struct macb *bp, int budget);
 };
 
+struct macb_config {
+	u32			caps;
+	unsigned int		dma_burst_length;
+};
+
 struct macb {
 	void __iomem		*regs;
 

@@ -595,6 +609,7 @@ struct macb {
 	unsigned int 		duplex;
 
 	u32			caps;
+	unsigned int		dma_burst_length;
 
 	phy_interface_t		phy_interface;
 

@@ -615,7 +630,7 @@ void macb_get_hwaddr(struct macb *bp);
 
 static inline bool macb_is_gem(struct macb *bp)
 {
-	return MACB_BFEXT(IDNUM, macb_readl(bp, MID)) == 0x2;
+	return !!(bp->caps & MACB_CAPS_MACB_IS_GEM);
 }
 
 #endif /* _MACB_H */

index 91870e9..2e4bfe3 100644
@@ -52,6 +52,9 @@
 					| MACB_BIT(TXERR))
 #define MACB_TX_INT_FLAGS	(MACB_TX_ERR_FLAGS | MACB_BIT(TCOMP))
 
+#define MACB_MAX_TX_LEN		((unsigned int)((1 << MACB_TX_FRMLEN_SIZE) - 1))
+#define GEM_MAX_TX_LEN		((unsigned int)((1 << GEM_TX_FRMLEN_SIZE) - 1))
+
 /*
  * Graceful stop timeouts in us. We should allow up to
  * 1 frame time (10 Mbits/s, full-duplex, ignoring collisions)

@@ -468,6 +471,24 @@ static int macb_halt_tx(struct macb *bp)
 	return -ETIMEDOUT;
 }
 
+static void macb_tx_unmap(struct macb *bp, struct macb_tx_skb *tx_skb)
+{
+	if (tx_skb->mapping) {
+		if (tx_skb->mapped_as_page)
+			dma_unmap_page(&bp->pdev->dev, tx_skb->mapping,
+				       tx_skb->size, DMA_TO_DEVICE);
+		else
+			dma_unmap_single(&bp->pdev->dev, tx_skb->mapping,
+					 tx_skb->size, DMA_TO_DEVICE);
+		tx_skb->mapping = 0;
+	}
+
+	if (tx_skb->skb) {
+		dev_kfree_skb_any(tx_skb->skb);
+		tx_skb->skb = NULL;
+	}
+}
+
 static void macb_tx_error_task(struct work_struct *work)
 {
 	struct macb	*bp = container_of(work, struct macb, tx_error_task);

@@ -505,10 +526,23 @@ static void macb_tx_error_task(struct work_struct *work)
 		skb = tx_skb->skb;
 
 		if (ctrl & MACB_BIT(TX_USED)) {
-			netdev_vdbg(bp->dev, "txerr skb %u (data %p) TX complete\n",
-				    macb_tx_ring_wrap(tail), skb->data);
-			bp->stats.tx_packets++;
-			bp->stats.tx_bytes += skb->len;
+			/* skb is set for the last buffer of the frame */
+			while (!skb) {
+				macb_tx_unmap(bp, tx_skb);
+				tail++;
+				tx_skb = macb_tx_skb(bp, tail);
+				skb = tx_skb->skb;
+			}
+
+			/* ctrl still refers to the first buffer descriptor
+			 * since it's the only one written back by the hardware
+			 */
+			if (!(ctrl & MACB_BIT(TX_BUF_EXHAUSTED))) {
+				netdev_vdbg(bp->dev, "txerr skb %u (data %p) TX complete\n",
+					    macb_tx_ring_wrap(tail), skb->data);
+				bp->stats.tx_packets++;
+				bp->stats.tx_bytes += skb->len;
+			}
 		} else {
 			/*
 			 * "Buffers exhausted mid-frame" errors may only happen

@@ -522,10 +556,7 @@ static void macb_tx_error_task(struct work_struct *work)
 			desc->ctrl = ctrl | MACB_BIT(TX_USED);
 		}
 
-		dma_unmap_single(&bp->pdev->dev, tx_skb->mapping, skb->len,
-				 DMA_TO_DEVICE);
-		tx_skb->skb = NULL;
-		dev_kfree_skb(skb);
+		macb_tx_unmap(bp, tx_skb);
 	}
 
 	/* Make descriptor updates visible to hardware */

@@ -573,20 +604,35 @@ static void macb_tx_interrupt(struct macb *bp)
 
 		ctrl = desc->ctrl;
 
+		/* TX_USED bit is only set by hardware on the very first buffer
+		 * descriptor of the transmitted frame.
+		 */
 		if (!(ctrl & MACB_BIT(TX_USED)))
 			break;
 
-		tx_skb = macb_tx_skb(bp, tail);
-		skb = tx_skb->skb;
+		/* Process all buffers of the current transmitted frame */
+		for (;; tail++) {
+			tx_skb = macb_tx_skb(bp, tail);
+			skb = tx_skb->skb;
+
+			/* First, update TX stats if needed */
+			if (skb) {
+				netdev_vdbg(bp->dev, "skb %u (data %p) TX complete\n",
+					    macb_tx_ring_wrap(tail), skb->data);
+				bp->stats.tx_packets++;
+				bp->stats.tx_bytes += skb->len;
+			}
 
-		netdev_vdbg(bp->dev, "skb %u (data %p) TX complete\n",
-			macb_tx_ring_wrap(tail), skb->data);
-		dma_unmap_single(&bp->pdev->dev, tx_skb->mapping, skb->len,
-				 DMA_TO_DEVICE);
-		bp->stats.tx_packets++;
-		bp->stats.tx_bytes += skb->len;
-		tx_skb->skb = NULL;
-		dev_kfree_skb_irq(skb);
+			/* Now we can safely release resources */
+			macb_tx_unmap(bp, tx_skb);
+
+			/* skb is set only for the last buffer of the frame.
+			 * WARNING: at this point skb has been freed by
+			 * macb_tx_unmap().
+			 */
+			if (skb)
+				break;
+		}
 	}
 
 	bp->tx_tail = tail;

@@ -1002,15 +1048,145 @@ static void macb_poll_controller(struct net_device *dev)
 }
 #endif
 
-static int macb_start_xmit(struct sk_buff *skb, struct net_device *dev)
+static inline unsigned int macb_count_tx_descriptors(struct macb *bp,
+						     unsigned int len)
+{
+	return (len + bp->max_tx_length - 1) / bp->max_tx_length;
+}
+
+static unsigned int macb_tx_map(struct macb *bp,
+				struct sk_buff *skb)
 {
-	struct macb *bp = netdev_priv(dev);
 	dma_addr_t mapping;
-	unsigned int len, entry;
+	unsigned int len, entry, i, tx_head = bp->tx_head;
+	struct macb_tx_skb *tx_skb = NULL;
 	struct macb_dma_desc *desc;
-	struct macb_tx_skb *tx_skb;
+	unsigned int offset, size, count = 0;
+	unsigned int f, nr_frags = skb_shinfo(skb)->nr_frags;
+	unsigned int eof = 1;
 	u32 ctrl;
+
+	/* First, map non-paged data */
+	len = skb_headlen(skb);
+	offset = 0;
+	while (len) {
+		size = min(len, bp->max_tx_length);
+		entry = macb_tx_ring_wrap(tx_head);
+		tx_skb = &bp->tx_skb[entry];
+
+		mapping = dma_map_single(&bp->pdev->dev,
+					 skb->data + offset,
+					 size, DMA_TO_DEVICE);
+		if (dma_mapping_error(&bp->pdev->dev, mapping))
+			goto dma_error;
+
+		/* Save info to properly release resources */
+		tx_skb->skb = NULL;
+		tx_skb->mapping = mapping;
+		tx_skb->size = size;
+		tx_skb->mapped_as_page = false;
+
+		len -= size;
+		offset += size;
+		count++;
+		tx_head++;
+	}
+
+	/* Then, map paged data from fragments */
+	for (f = 0; f < nr_frags; f++) {
+		const skb_frag_t *frag = &skb_shinfo(skb)->frags[f];
+
+		len = skb_frag_size(frag);
+		offset = 0;
+		while (len) {
+			size = min(len, bp->max_tx_length);
+			entry = macb_tx_ring_wrap(tx_head);
+			tx_skb = &bp->tx_skb[entry];
+
+			mapping = skb_frag_dma_map(&bp->pdev->dev, frag,
+						   offset, size, DMA_TO_DEVICE);
+			if (dma_mapping_error(&bp->pdev->dev, mapping))
+				goto dma_error;
+
+			/* Save info to properly release resources */
+			tx_skb->skb = NULL;
+			tx_skb->mapping = mapping;
+			tx_skb->size = size;
+			tx_skb->mapped_as_page = true;
+
+			len -= size;
+			offset += size;
+			count++;
+			tx_head++;
+		}
+	}
+
+	/* Should never happen */
+	if (unlikely(tx_skb == NULL)) {
+		netdev_err(bp->dev, "BUG! empty skb!\n");
+		return 0;
+	}
+
+	/* This is the last buffer of the frame: save socket buffer */
+	tx_skb->skb = skb;
+
+	/* Update TX ring: update buffer descriptors in reverse order
+	 * to avoid race condition
+	 */
+
+	/* Set 'TX_USED' bit in buffer descriptor at tx_head position
+	 * to set the end of TX queue
+	 */
+	i = tx_head;
+	entry = macb_tx_ring_wrap(i);
+	ctrl = MACB_BIT(TX_USED);
+	desc = &bp->tx_ring[entry];
+	desc->ctrl = ctrl;
+
+	do {
+		i--;
+		entry = macb_tx_ring_wrap(i);
+		tx_skb = &bp->tx_skb[entry];
+		desc = &bp->tx_ring[entry];
+
+		ctrl = (u32)tx_skb->size;
+		if (eof) {
+			ctrl |= MACB_BIT(TX_LAST);
+			eof = 0;
+		}
+		if (unlikely(entry == (TX_RING_SIZE - 1)))
+			ctrl |= MACB_BIT(TX_WRAP);
+
+		/* Set TX buffer descriptor */
+		desc->addr = tx_skb->mapping;
+		/* desc->addr must be visible to hardware before clearing
+		 * 'TX_USED' bit in desc->ctrl.
+		 */
+		wmb();
+		desc->ctrl = ctrl;
+	} while (i != bp->tx_head);
+
+	bp->tx_head = tx_head;
+
+	return count;
+
+dma_error:
+	netdev_err(bp->dev, "TX DMA map failed\n");
+
+	for (i = bp->tx_head; i != tx_head; i++) {
+		tx_skb = macb_tx_skb(bp, i);
+
+		macb_tx_unmap(bp, tx_skb);
+	}
+
+	return 0;
+}
+
+static int macb_start_xmit(struct sk_buff *skb, struct net_device *dev)
+{
+	struct macb *bp = netdev_priv(dev);
 	unsigned long flags;
+	unsigned int count, nr_frags, frag_size, f;
 
 #if defined(DEBUG) && defined(VERBOSE_DEBUG)
 	netdev_vdbg(bp->dev,

@@ -1021,44 +1197,34 @@ static int macb_start_xmit(struct sk_buff *skb, struct net_device *dev)
 		       skb->data, 16, true);
 #endif
 
-	len = skb->len;
+	/* Count how many TX buffer descriptors are needed to send this
+	 * socket buffer: skb fragments of jumbo frames may need to be
+	 * splitted into many buffer descriptors.
+	 */
+	count = macb_count_tx_descriptors(bp, skb_headlen(skb));
+	nr_frags = skb_shinfo(skb)->nr_frags;
+	for (f = 0; f < nr_frags; f++) {
+		frag_size = skb_frag_size(&skb_shinfo(skb)->frags[f]);
+		count += macb_count_tx_descriptors(bp, frag_size);
+	}
+
 	spin_lock_irqsave(&bp->lock, flags);
 
 	/* This is a hard error, log it. */
-	if (CIRC_SPACE(bp->tx_head, bp->tx_tail, TX_RING_SIZE) < 1) {
+	if (CIRC_SPACE(bp->tx_head, bp->tx_tail, TX_RING_SIZE) < count) {
 		netif_stop_queue(dev);
 		spin_unlock_irqrestore(&bp->lock, flags);
-		netdev_err(bp->dev, "BUG! Tx Ring full when queue awake!\n");
 		netdev_dbg(bp->dev, "tx_head = %u, tx_tail = %u\n",
 			   bp->tx_head, bp->tx_tail);
 		return NETDEV_TX_BUSY;
 	}
 
-	entry = macb_tx_ring_wrap(bp->tx_head);
-	netdev_vdbg(bp->dev, "Allocated ring entry %u\n", entry);
-	mapping = dma_map_single(&bp->pdev->dev, skb->data,
-				 len, DMA_TO_DEVICE);
-	if (dma_mapping_error(&bp->pdev->dev, mapping)) {
+	/* Map socket buffer for DMA transfer */
+	if (!macb_tx_map(bp, skb)) {
 		dev_kfree_skb_any(skb);
 		goto unlock;
 	}
 
-	bp->tx_head++;
-	tx_skb = &bp->tx_skb[entry];
-	tx_skb->skb = skb;
-	tx_skb->mapping = mapping;
-	netdev_vdbg(bp->dev, "Mapped skb data %p to DMA addr %08lx\n",
-		   skb->data, (unsigned long)mapping);
-
-	ctrl = MACB_BF(TX_FRMLEN, len);
-	ctrl |= MACB_BIT(TX_LAST);
-	if (entry == (TX_RING_SIZE - 1))
-		ctrl |= MACB_BIT(TX_WRAP);
-
-	desc = &bp->tx_ring[entry];
-	desc->addr = mapping;
-	desc->ctrl = ctrl;
-
 	/* Make newly initialized descriptor visible to hardware */
 	wmb();
 

@@ -1776,7 +1942,12 @@ static const struct net_device_ops macb_netdev_ops = {
 
 #if defined(CONFIG_OF)
 static struct macb_config pc302gem_config = {
-	.caps = MACB_CAPS_GIGABIT_MODE_AVAILABLE,
+	.caps = MACB_CAPS_SG_DISABLED | MACB_CAPS_GIGABIT_MODE_AVAILABLE,
+	.dma_burst_length = 16,
+};
+
+static struct macb_config sama5d3_config = {
+	.caps = MACB_CAPS_SG_DISABLED | MACB_CAPS_GIGABIT_MODE_AVAILABLE,
 	.dma_burst_length = 16,
 };
 

@@ -1786,6 +1957,7 @@ static const struct of_device_id macb_dt_ids[] = {
 	{ .compatible = "cdns,macb" },
 	{ .compatible = "cdns,pc302-gem", .data = &pc302gem_config },
 	{ .compatible = "cdns,gem", .data = &pc302gem_config },
+	{ .compatible = "atmel,sama5d3-gem", .data = &sama5d3_config },
 	{ /* sentinel */ }
 };
 MODULE_DEVICE_TABLE(of, macb_dt_ids);

@@ -1864,9 +2036,6 @@ static int __init macb_probe(struct platform_device *pdev)
 
 	SET_NETDEV_DEV(dev, &pdev->dev);
 
-	/* TODO: Actually, we have some interesting features... */
-	dev->features |= 0;
-
 	bp = netdev_priv(dev);
 	bp->pdev = pdev;
 	bp->dev = dev;

@@ -1938,17 +2107,25 @@ static int __init macb_probe(struct platform_device *pdev)
 
 	/* setup appropriated routines according to adapter type */
 	if (macb_is_gem(bp)) {
+		bp->max_tx_length = GEM_MAX_TX_LEN;
 		bp->macbgem_ops.mog_alloc_rx_buffers = gem_alloc_rx_buffers;
 		bp->macbgem_ops.mog_free_rx_buffers = gem_free_rx_buffers;
 		bp->macbgem_ops.mog_init_rings = gem_init_rings;
 		bp->macbgem_ops.mog_rx = gem_rx;
 	} else {
+		bp->max_tx_length = MACB_MAX_TX_LEN;
 		bp->macbgem_ops.mog_alloc_rx_buffers = macb_alloc_rx_buffers;
 		bp->macbgem_ops.mog_free_rx_buffers = macb_free_rx_buffers;
 		bp->macbgem_ops.mog_init_rings = macb_init_rings;
 		bp->macbgem_ops.mog_rx = macb_rx;
 	}
 
+	/* Set features */
+	dev->hw_features = NETIF_F_SG;
+	if (bp->caps & MACB_CAPS_SG_DISABLED)
+		dev->hw_features &= ~NETIF_F_SG;
+	dev->features = dev->hw_features;
+
 	/* Set MII management clock divider */
 	config = macb_mdc_clk_div(bp);
 	config |= macb_dbw(bp);

index 7ce751b..7bf8285 100644
@@ -335,6 +335,7 @@
 #define MACB_CAPS_ISR_CLEAR_ON_WRITE		0x00000001
 #define MACB_CAPS_FIFO_MODE			0x10000000
 #define MACB_CAPS_GIGABIT_MODE_AVAILABLE	0x20000000
+#define MACB_CAPS_SG_DISABLED			0x40000000
 #define MACB_CAPS_MACB_IS_GEM			0x80000000
 
 /* Bit manipulation macros */

@@ -468,14 +469,23 @@ struct macb_dma_desc {
 #define MACB_TX_USED_OFFSET			31
 #define MACB_TX_USED_SIZE			1
 
+#define GEM_TX_FRMLEN_OFFSET			0
+#define GEM_TX_FRMLEN_SIZE			14
+
 /**
  * struct macb_tx_skb - data about an skb which is being transmitted
- * @skb: skb currently being transmitted
- * @mapping: DMA address of the skb's data buffer
+ * @skb: skb currently being transmitted, only set for the last buffer
+ *       of the frame
+ * @mapping: DMA address of the skb's fragment buffer
+ * @size: size of the DMA mapped buffer
+ * @mapped_as_page: true when buffer was mapped with skb_frag_dma_map(),
+ *                  false when buffer was mapped with dma_map_single()
  */
 struct macb_tx_skb {
 	struct sk_buff		*skb;
 	dma_addr_t		mapping;
+	size_t			size;
+	bool			mapped_as_page;
 };
 
 /*

@@ -617,6 +627,7 @@ struct macb {
 	struct sk_buff *skb;			/* holds skb until xmit interrupt completes */
 	dma_addr_t skb_physaddr;		/* phys addr from pci_map_single */
 	int skb_length;				/* saved skb length for pci_unmap_single */
+	unsigned int		max_tx_length;
 };
 
 extern const struct ethtool_ops macb_ethtool_ops;

index 2e4bfe3..cc36269 100644
@@ -1525,6 +1525,10 @@ static void macb_configure_dma(struct macb *bp)
 			dmacfg = GEM_BFINS(FBLDO, bp->dma_burst_length, dmacfg);
 		dmacfg |= GEM_BIT(TXPBMS) | GEM_BF(RXBMS, -1L);
 		dmacfg &= ~GEM_BIT(ENDIA);
+		if (bp->dev->features & NETIF_F_HW_CSUM)
+			dmacfg |= GEM_BIT(TXCOEN);
+		else
+			dmacfg &= ~GEM_BIT(TXCOEN);
 		netdev_dbg(bp->dev, "Cadence configure DMA with 0x%08x\n",
 			   dmacfg);
 		gem_writel(bp, DMACFG, dmacfg);

@@ -1925,6 +1929,27 @@ int macb_ioctl(struct net_device *dev, struct ifreq *rq, int cmd)
 }
 EXPORT_SYMBOL_GPL(macb_ioctl);
 
+static int macb_set_features(struct net_device *netdev,
+			     netdev_features_t features)
+{
+	struct macb *bp = netdev_priv(netdev);
+	netdev_features_t changed = features ^ netdev->features;
+
+	/* TX checksum offload */
+	if ((changed & NETIF_F_HW_CSUM) && macb_is_gem(bp)) {
+		u32 dmacfg;
+
+		dmacfg = gem_readl(bp, DMACFG);
+		if (features & NETIF_F_HW_CSUM)
+			dmacfg |= GEM_BIT(TXCOEN);
+		else
+			dmacfg &= ~GEM_BIT(TXCOEN);
+		gem_writel(bp, DMACFG, dmacfg);
+	}
+
+	return 0;
+}
+
 static const struct net_device_ops macb_netdev_ops = {
 	.ndo_open		= macb_open,
 	.ndo_stop		= macb_close,

@@ -1938,6 +1963,7 @@ static const struct net_device_ops macb_netdev_ops = {
 #ifdef CONFIG_NET_POLL_CONTROLLER
 	.ndo_poll_controller	= macb_poll_controller,
 #endif
+	.ndo_set_features	= macb_set_features,
 };
 
 #if defined(CONFIG_OF)

@@ -2122,6 +2148,9 @@ static int __init macb_probe(struct platform_device *pdev)
 
 	/* Set features */
 	dev->hw_features = NETIF_F_SG;
+	/* Checksum offload is only available on gem with packet buffer */
+	if (macb_is_gem(bp) && !(bp->caps & MACB_CAPS_FIFO_MODE))
+		dev->hw_features |= NETIF_F_HW_CSUM;
 	if (bp->caps & MACB_CAPS_SG_DISABLED)
 		dev->hw_features &= ~NETIF_F_SG;
 	dev->features = dev->hw_features;

index cc36269..6836f88 100644
@@ -765,6 +765,10 @@ static int gem_rx(struct macb *bp, int budget)
 
 		skb->protocol = eth_type_trans(skb, bp->dev);
 		skb_checksum_none_assert(skb);
+		if (bp->dev->features & NETIF_F_RXCSUM &&
+		    !(bp->dev->flags & IFF_PROMISC) &&
+		    GEM_BFEXT(RX_CSUM, ctrl) & GEM_RX_CSUM_CHECKED_MASK)
+			skb->ip_summed = CHECKSUM_UNNECESSARY;
 
 		bp->stats.rx_packets++;
 		bp->stats.rx_bytes += skb->len;

@@ -1549,6 +1553,8 @@ static void macb_init_hw(struct macb *bp)
 	config |= MACB_BIT(BIG);		/* Receive oversized frames */
 	if (bp->dev->flags & IFF_PROMISC)
 		config |= MACB_BIT(CAF);	/* Copy All Frames */
+	else if (macb_is_gem(bp) && bp->dev->features & NETIF_F_RXCSUM)
+		config |= GEM_BIT(RXCOEN);
 	if (!(bp->dev->flags & IFF_BROADCAST))
 		config |= MACB_BIT(NBC);	/* No BroadCast */
 	config |= macb_dbw(bp);

@@ -1662,13 +1668,22 @@ void macb_set_rx_mode(struct net_device *dev)
 
 	cfg = macb_readl(bp, NCFGR);
 
-	if (dev->flags & IFF_PROMISC)
+	if (dev->flags & IFF_PROMISC) {
 		/* Enable promiscuous mode */
 		cfg |= MACB_BIT(CAF);
-	else if (dev->flags & (~IFF_PROMISC))
-		 /* Disable promiscuous mode */
+
+		/* Disable RX checksum offload */
+		if (macb_is_gem(bp))
+			cfg &= ~GEM_BIT(RXCOEN);
+	} else {
+		/* Disable promiscuous mode */
 		cfg &= ~MACB_BIT(CAF);
 
+		/* Enable RX checksum offload only if requested */
+		if (macb_is_gem(bp) && dev->features & NETIF_F_RXCSUM)
+			cfg |= GEM_BIT(RXCOEN);
+	}
+
 	if (dev->flags & IFF_ALLMULTI) {
 		/* Enable all multicast mode */
 		macb_or_gem_writel(bp, HRB, -1);

@@ -1947,6 +1962,19 @@ static int macb_set_features(struct net_device *netdev,
 		gem_writel(bp, DMACFG, dmacfg);
 	}
 
+	/* RX checksum offload */
+	if ((changed & NETIF_F_RXCSUM) && macb_is_gem(bp)) {
+		u32 netcfg;
+
+		netcfg = gem_readl(bp, NCFGR);
+		if (features & NETIF_F_RXCSUM &&
+		    !(netdev->flags & IFF_PROMISC))
+			netcfg |= GEM_BIT(RXCOEN);
+		else
+			netcfg &= ~GEM_BIT(RXCOEN);
+		gem_writel(bp, NCFGR, netcfg);
+	}
+
 	return 0;
 }
 

@@ -2150,7 +2178,7 @@ static int __init macb_probe(struct platform_device *pdev)
 	dev->hw_features = NETIF_F_SG;
 	/* Checksum offload is only available on gem with packet buffer */
 	if (macb_is_gem(bp) && !(bp->caps & MACB_CAPS_FIFO_MODE))
-		dev->hw_features |= NETIF_F_HW_CSUM;
+		dev->hw_features |= NETIF_F_HW_CSUM | NETIF_F_RXCSUM;
 	if (bp->caps & MACB_CAPS_SG_DISABLED)
 		dev->hw_features &= ~NETIF_F_SG;
 	dev->features = dev->hw_features;

index 7bf8285..517c09d 100644
@@ -164,6 +164,8 @@
 #define GEM_CLK_SIZE				3
 #define GEM_DBW_OFFSET				21
 #define GEM_DBW_SIZE				2
+#define GEM_RXCOEN_OFFSET			24
+#define GEM_RXCOEN_SIZE				1
 
 /* Constants for data bus width. */
 #define GEM_DBW32				0

@@ -452,6 +454,14 @@ struct macb_dma_desc {
 #define MACB_RX_BROADCAST_OFFSET		31
 #define MACB_RX_BROADCAST_SIZE			1
 
+/* RX checksum offload disabled: bit 24 clear in NCFGR */
+#define GEM_RX_TYPEID_MATCH_OFFSET		22
+#define GEM_RX_TYPEID_MATCH_SIZE		2
+
+/* RX checksum offload enabled: bit 24 set in NCFGR */
+#define GEM_RX_CSUM_OFFSET			22
+#define GEM_RX_CSUM_SIZE			2
+
 #define MACB_TX_FRMLEN_OFFSET			0
 #define MACB_TX_FRMLEN_SIZE			11
 #define MACB_TX_LAST_OFFSET			15

@@ -472,6 +482,15 @@ struct macb_dma_desc {
 #define GEM_TX_FRMLEN_OFFSET			0
 #define GEM_TX_FRMLEN_SIZE			14
 
+/* Buffer descriptor constants */
+#define GEM_RX_CSUM_NONE			0
+#define GEM_RX_CSUM_IP_ONLY			1
+#define GEM_RX_CSUM_IP_TCP			2
+#define GEM_RX_CSUM_IP_UDP			3
+
+/* limit RX checksum offload to TCP and UDP packets */
+#define GEM_RX_CSUM_CHECKED_MASK		2
+
 /**
  * struct macb_tx_skb - data about an skb which is being transmitted
  * @skb: skb currently being transmitted, only set for the last buffer

index 6836f88..ca5d779 100644
@@ -2005,6 +2005,11 @@ static struct macb_config sama5d3_config = {
 	.dma_burst_length = 16,
 };
 
+static struct macb_config sama5d4_config = {
+	.caps = 0,
+	.dma_burst_length = 4,
+};
+
 static const struct of_device_id macb_dt_ids[] = {
 	{ .compatible = "cdns,at32ap7000-macb" },
 	{ .compatible = "cdns,at91sam9260-macb" },

@@ -2012,6 +2017,7 @@ static const struct of_device_id macb_dt_ids[] = {
 	{ .compatible = "cdns,pc302-gem", .data = &pc302gem_config },
 	{ .compatible = "cdns,gem", .data = &pc302gem_config },
 	{ .compatible = "atmel,sama5d3-gem", .data = &sama5d3_config },
+	{ .compatible = "atmel,sama5d4-gem", .data = &sama5d4_config },
 	{ /* sentinel */ }
 };
 MODULE_DEVICE_TABLE(of, macb_dt_ids);