[PATCH] LSO feature added to Cadence GEM driver

[PATCH] LSO feature added to Cadence GEM driver

[Rafal Ozieblo]

New Cadence GEM hardware support Large Segment Offload (LSO):
TCP segmentation offload (TSO) as well as UDP fragmentation
offload (UFO). Support for those features was added to the driver.

Signed-off-by: Rafal Ozieblo <rafalo@cadence.com>
---
 drivers/net/ethernet/cadence/macb.c | 141 +++++++++++++++++++++++++++++++++---
 drivers/net/ethernet/cadence/macb.h |  14 ++++
 2 files changed, 143 insertions(+), 12 deletions(-)

diff --git a/drivers/net/ethernet/cadence/macb.c b/drivers/net/ethernet/cadence/macb.c
index b32444a..f659d57 100644
--- a/drivers/net/ethernet/cadence/macb.c
+++ b/drivers/net/ethernet/cadence/macb.c
@@ -32,7 +32,9 @@
 #include <linux/of_gpio.h>
 #include <linux/of_mdio.h>
 #include <linux/of_net.h>
-
+#include <linux/ip.h>
+#include <linux/udp.h>
+#include <linux/tcp.h>
 #include "macb.h"
 
 #define MACB_RX_BUFFER_SIZE	128
@@ -53,8 +55,10 @@
 					| 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))
+/* Max length of transmit frame must be a multiple of 8 bytes */
+#define MACB_TX_LEN_ALIGN	8
+#define MACB_MAX_TX_LEN		((unsigned int)((1 << MACB_TX_FRMLEN_SIZE) - 1) & ~((unsigned int)(MACB_TX_LEN_ALIGN - 1)))
+#define GEM_MAX_TX_LEN		((unsigned int)((1 << GEM_TX_FRMLEN_SIZE) - 1) & ~((unsigned int)(MACB_TX_LEN_ALIGN - 1)))
 
 #define GEM_MTU_MIN_SIZE	68
 
@@ -1212,7 +1216,8 @@ static void macb_poll_controller(struct net_device *dev)
 
 static unsigned int macb_tx_map(struct macb *bp,
 				struct macb_queue *queue,
-				struct sk_buff *skb)
+				struct sk_buff *skb,
+				unsigned int hdrlen)
 {
 	dma_addr_t mapping;
 	unsigned int len, entry, i, tx_head = queue->tx_head;
@@ -1220,14 +1225,27 @@ static unsigned int macb_tx_map(struct macb *bp,
 	struct macb_dma_desc *desc;
 	unsigned int offset, size, count = 0;
 	unsigned int f, nr_frags = skb_shinfo(skb)->nr_frags;
-	unsigned int eof = 1;
-	u32 ctrl;
+	unsigned int eof = 1, mss_mfs = 0;
+	u32 ctrl, lso_ctrl = 0, seq_ctrl = 0;
+
+	/* LSO */
+	if (skb_shinfo(skb)->gso_size != 0) {
+		if (IPPROTO_UDP == (((struct iphdr *)skb_network_header(skb))->protocol))
+			/* UDP - UFO */
+			lso_ctrl = MACB_LSO_UFO_ENABLE;
+		else
+			/* TCP - TSO */
+			lso_ctrl = MACB_LSO_TSO_ENABLE;
+	}
 
 	/* First, map non-paged data */
 	len = skb_headlen(skb);
+
+	/* first buffer length */
+	size = hdrlen;
+
 	offset = 0;
 	while (len) {
-		size = min(len, bp->max_tx_length);
 		entry = macb_tx_ring_wrap(tx_head);
 		tx_skb = &queue->tx_skb[entry];
 
@@ -1247,6 +1265,8 @@ static unsigned int macb_tx_map(struct macb *bp,
 		offset += size;
 		count++;
 		tx_head++;
+
+		size = min(len, bp->max_tx_length);
 	}
 
 	/* Then, map paged data from fragments */
@@ -1300,6 +1320,20 @@ static unsigned int macb_tx_map(struct macb *bp,
 	desc = &queue->tx_ring[entry];
 	desc->ctrl = ctrl;
 
+	if (lso_ctrl) {
+		if (lso_ctrl == MACB_LSO_UFO_ENABLE)
+			/* include header and FCS in value given to h/w */
+			mss_mfs = skb_shinfo(skb)->gso_size +
+					skb_transport_offset(skb) + 4;
+		else /* TSO */ {
+			mss_mfs = skb_shinfo(skb)->gso_size;
+			/* TCP Sequence Number Source Select
+			 * can be set only for TSO
+			 */
+			seq_ctrl = 0;
+		}
+	}
+
 	do {
 		i--;
 		entry = macb_tx_ring_wrap(i);
@@ -1314,6 +1348,16 @@ static unsigned int macb_tx_map(struct macb *bp,
 		if (unlikely(entry == (TX_RING_SIZE - 1)))
 			ctrl |= MACB_BIT(TX_WRAP);
 
+		/* First descriptor is header descriptor */
+		if (i == queue->tx_head) {
+			ctrl |= MACB_BF(TX_LSO, lso_ctrl);
+			ctrl |= MACB_BF(TX_TCP_SEQ_SRC, seq_ctrl);
+		} else
+			/* Only set MSS/MFS on payload descriptors
+			 * (second or later descriptor)
+			 */
+			ctrl |= MACB_BF(MSS_MFS, mss_mfs);
+
 		/* Set TX buffer descriptor */
 		macb_set_addr(desc, tx_skb->mapping);
 		/* desc->addr must be visible to hardware before clearing
@@ -1339,6 +1383,37 @@ static unsigned int macb_tx_map(struct macb *bp,
 	return 0;
 }
 
+static int macb_lso_check_compatibility(struct sk_buff *skb, unsigned int hdrlen)
+{
+	unsigned int nr_frags, f;
+
+	if (skb_shinfo(skb)->gso_size == 0)
+		/* not LSO */
+		return -EPERM;
+
+	/* there is only one buffer */
+	if (!skb_is_nonlinear(skb))
+		return 0;
+
+	/* For LSO:
+	 * When software supplies two or more payload buffers all payload buffers
+	 * apart from the last must be a multiple of 8 bytes in size.
+	 */
+	if (!IS_ALIGNED(skb_headlen(skb) - hdrlen, MACB_TX_LEN_ALIGN))
+		return -EPERM;
+
+	nr_frags = skb_shinfo(skb)->nr_frags;
+	/* No need to check last fragment */
+	nr_frags--;
+	for (f = 0; f < nr_frags; f++) {
+		const skb_frag_t *frag = &skb_shinfo(skb)->frags[f];
+
+		if (!IS_ALIGNED(skb_frag_size(frag), MACB_TX_LEN_ALIGN))
+			return -EPERM;
+	}
+	return 0;
+}
+
 static inline int macb_clear_csum(struct sk_buff *skb)
 {
 	/* no change for packets without checksum offloading */
@@ -1363,7 +1438,33 @@ static int macb_start_xmit(struct sk_buff *skb, struct net_device *dev)
 	struct macb *bp = netdev_priv(dev);
 	struct macb_queue *queue = &bp->queues[queue_index];
 	unsigned long flags;
-	unsigned int count, nr_frags, frag_size, f;
+	unsigned int desc_cnt, nr_frags, frag_size, f;
+	unsigned int is_lso = 0, is_udp, hdrlen;
+
+	is_lso = (skb_shinfo(skb)->gso_size != 0);
+
+	if (is_lso) {
+		is_udp = (IPPROTO_UDP == (((struct iphdr *)skb_network_header(skb))->protocol));
+
+		/* length of headers */
+		if (is_udp)
+			/* only queue eth + ip headers separately for UDP */
+			hdrlen = skb_transport_offset(skb);
+		else
+			hdrlen = skb_transport_offset(skb) + tcp_hdrlen(skb);
+		if (skb_headlen(skb) < hdrlen) {
+			netdev_err(bp->dev, "Error - LSO headers fragmented!!!\n");
+			/* if this is required, would need to copy to single buffer */
+			return NETDEV_TX_BUSY;
+		}
+		if (macb_lso_check_compatibility(skb, hdrlen)) {
+			if (skb_linearize(skb)) {
+				netdev_err(bp->dev, "Can't linearize buffer\n");
+				return NETDEV_TX_BUSY;
+			}
+		}
+	} else
+		hdrlen = min(skb_headlen(skb), bp->max_tx_length);
 
 #if defined(DEBUG) && defined(VERBOSE_DEBUG)
 	netdev_vdbg(bp->dev,
@@ -1378,17 +1479,21 @@ static int macb_start_xmit(struct sk_buff *skb, struct net_device *dev)
 	 * socket buffer: skb fragments of jumbo frames may need to be
 	 * split into many buffer descriptors.
 	 */
-	count = DIV_ROUND_UP(skb_headlen(skb), bp->max_tx_length);
+	if (is_lso && (skb_headlen(skb) > hdrlen))
+		/* extra header descriptor if also payload in first buffer */
+		desc_cnt = DIV_ROUND_UP((skb_headlen(skb) - hdrlen), bp->max_tx_length) + 1;
+	else
+		desc_cnt = DIV_ROUND_UP(skb_headlen(skb), bp->max_tx_length);
 	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 += DIV_ROUND_UP(frag_size, bp->max_tx_length);
+		desc_cnt += DIV_ROUND_UP(frag_size, bp->max_tx_length);
 	}
 
 	spin_lock_irqsave(&bp->lock, flags);
 
 	/* This is a hard error, log it. */
-	if (CIRC_SPACE(queue->tx_head, queue->tx_tail, TX_RING_SIZE) < count) {
+	if (CIRC_SPACE(queue->tx_head, queue->tx_tail, TX_RING_SIZE) < desc_cnt) {
 		netif_stop_subqueue(dev, queue_index);
 		spin_unlock_irqrestore(&bp->lock, flags);
 		netdev_dbg(bp->dev, "tx_head = %u, tx_tail = %u\n",
@@ -1396,13 +1501,19 @@ static int macb_start_xmit(struct sk_buff *skb, struct net_device *dev)
 		return NETDEV_TX_BUSY;
 	}
 
+	if (is_lso) {
+		if (is_udp)
+			/* zero UDP checksum, not calculated by h/w for UFO */
+			udp_hdr(skb)->check = 0;
+	}
+
 	if (macb_clear_csum(skb)) {
 		dev_kfree_skb_any(skb);
 		goto unlock;
 	}
 
 	/* Map socket buffer for DMA transfer */
-	if (!macb_tx_map(bp, queue, skb)) {
+	if (!macb_tx_map(bp, queue, skb, hdrlen)) {
 		dev_kfree_skb_any(skb);
 		goto unlock;
 	}
@@ -2501,6 +2612,12 @@ static int macb_init(struct platform_device *pdev)
 
 	/* Set features */
 	dev->hw_features = NETIF_F_SG;
+
+	/* Check LSO capability */
+	if (GEM_BFEXT(PBUF_LSO, gem_readl(bp, DCFG6)))
+		dev->hw_features |= NETIF_F_TSO
+				| NETIF_F_UFO;
+
 	/* 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 | NETIF_F_RXCSUM;
diff --git a/drivers/net/ethernet/cadence/macb.h b/drivers/net/ethernet/cadence/macb.h
index 8bed4b5..534aded 100644
--- a/drivers/net/ethernet/cadence/macb.h
+++ b/drivers/net/ethernet/cadence/macb.h
@@ -382,6 +382,10 @@
 #define GEM_TX_PKT_BUFF_OFFSET			21
 #define GEM_TX_PKT_BUFF_SIZE			1
 
+/* Bitfields in DCFG6. */
+#define GEM_PBUF_LSO_OFFSET			27
+#define GEM_PBUF_LSO_SIZE			1
+
 /* Constants for CLK */
 #define MACB_CLK_DIV8				0
 #define MACB_CLK_DIV16				1
@@ -414,6 +418,10 @@
 #define MACB_CAPS_SG_DISABLED			0x40000000
 #define MACB_CAPS_MACB_IS_GEM			0x80000000
 
+/* LSO settings */
+#define MACB_LSO_UFO_ENABLE			0x01
+#define MACB_LSO_TSO_ENABLE			0x02
+
 /* Bit manipulation macros */
 #define MACB_BIT(name)					\
 	(1 << MACB_##name##_OFFSET)
@@ -545,6 +553,12 @@ struct macb_dma_desc {
 #define MACB_TX_LAST_SIZE			1
 #define MACB_TX_NOCRC_OFFSET			16
 #define MACB_TX_NOCRC_SIZE			1
+#define MACB_MSS_MFS_OFFSET			16
+#define MACB_MSS_MFS_SIZE			14
+#define MACB_TX_LSO_OFFSET			17
+#define MACB_TX_LSO_SIZE			2
+#define MACB_TX_TCP_SEQ_SRC_OFFSET		19
+#define MACB_TX_TCP_SEQ_SRC_SIZE		1
 #define MACB_TX_BUF_EXHAUSTED_OFFSET		27
 #define MACB_TX_BUF_EXHAUSTED_SIZE		1
 #define MACB_TX_UNDERRUN_OFFSET			28
-- 
2.4.5

Re: [PATCH] LSO feature added to Cadence GEM driver

[Eric Dumazet]

On Mon, 2016-10-24 at 14:18 +0100, Rafal Ozieblo wrote:
> New Cadence GEM hardware support Large Segment Offload (LSO):
> TCP segmentation offload (TSO) as well as UDP fragmentation
> offload (UFO). Support for those features was added to the driver.
> 
> Signed-off-by: Rafal Ozieblo <rafalo@cadence.com>

...
>  
> +static int macb_lso_check_compatibility(struct sk_buff *skb, unsigned int hdrlen)
> +{
> +	unsigned int nr_frags, f;
> +
> +	if (skb_shinfo(skb)->gso_size == 0)
> +		/* not LSO */
> +		return -EPERM;
> +
> +	/* there is only one buffer */
> +	if (!skb_is_nonlinear(skb))
> +		return 0;
> +
> +	/* For LSO:
> +	 * When software supplies two or more payload buffers all payload buffers
> +	 * apart from the last must be a multiple of 8 bytes in size.
> +	 */
> +	if (!IS_ALIGNED(skb_headlen(skb) - hdrlen, MACB_TX_LEN_ALIGN))
> +		return -EPERM;
> +
> +	nr_frags = skb_shinfo(skb)->nr_frags;
> +	/* No need to check last fragment */
> +	nr_frags--;
> +	for (f = 0; f < nr_frags; f++) {
> +		const skb_frag_t *frag = &skb_shinfo(skb)->frags[f];
> +
> +		if (!IS_ALIGNED(skb_frag_size(frag), MACB_TX_LEN_ALIGN))
> +			return -EPERM;
> +	}
> +	return 0;
> +}
> +

Very strange hardware requirements ;(

You should implement an .ndo_features_check method
to perform the checks from core networking stack, and not from your
ndo_start_xmit()

This has the huge advantage of not falling back to skb_linearize(skb)
which is very likely to fail with ~64 KB skbs anyway.

(Your ndo_features_check() would request software GSO instead ...)

[PATCH v2] LSO feature added to Cadence GEM driver

[Rafal Ozieblo]

New Cadence GEM hardware support Large Segment Offload (LSO):
TCP segmentation offload (TSO) as well as UDP fragmentation
offload (UFO). Support for those features was added to the driver.

Signed-off-by: Rafal Ozieblo <rafalo@cadence.com>
---
Changed in v2:
macb_lso_check_compatibility() changed to macb_features_check() 
(with little modifications) and bind to .ndo_features_check.
(after Eric Dumazet suggestion)
---
 drivers/net/ethernet/cadence/macb.c | 142 +++++++++++++++++++++++++++++++++---
 drivers/net/ethernet/cadence/macb.h |  14 ++++
 2 files changed, 144 insertions(+), 12 deletions(-)

diff --git a/drivers/net/ethernet/cadence/macb.c b/drivers/net/ethernet/cadence/macb.c
index b32444a..30169fd 100644
--- a/drivers/net/ethernet/cadence/macb.c
+++ b/drivers/net/ethernet/cadence/macb.c
@@ -32,7 +32,9 @@
 #include <linux/of_gpio.h>
 #include <linux/of_mdio.h>
 #include <linux/of_net.h>
-
+#include <linux/ip.h>
+#include <linux/udp.h>
+#include <linux/tcp.h>
 #include "macb.h"
 
 #define MACB_RX_BUFFER_SIZE	128
@@ -53,10 +55,13 @@
 					| 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))
+/* Max length of transmit frame must be a multiple of 8 bytes */
+#define MACB_TX_LEN_ALIGN	8
+#define MACB_MAX_TX_LEN		((unsigned int)((1 << MACB_TX_FRMLEN_SIZE) - 1) & ~((unsigned int)(MACB_TX_LEN_ALIGN - 1)))
+#define GEM_MAX_TX_LEN		((unsigned int)((1 << GEM_TX_FRMLEN_SIZE) - 1) & ~((unsigned int)(MACB_TX_LEN_ALIGN - 1)))
 
 #define GEM_MTU_MIN_SIZE	68
+#define MACB_NETIF_LSO		(NETIF_F_TSO | NETIF_F_UFO)
 
 #define MACB_WOL_HAS_MAGIC_PACKET	(0x1 << 0)
 #define MACB_WOL_ENABLED		(0x1 << 1)
@@ -1212,7 +1217,8 @@ static void macb_poll_controller(struct net_device *dev)
 
 static unsigned int macb_tx_map(struct macb *bp,
 				struct macb_queue *queue,
-				struct sk_buff *skb)
+				struct sk_buff *skb,
+				unsigned int hdrlen)
 {
 	dma_addr_t mapping;
 	unsigned int len, entry, i, tx_head = queue->tx_head;
@@ -1220,14 +1226,27 @@ static unsigned int macb_tx_map(struct macb *bp,
 	struct macb_dma_desc *desc;
 	unsigned int offset, size, count = 0;
 	unsigned int f, nr_frags = skb_shinfo(skb)->nr_frags;
-	unsigned int eof = 1;
-	u32 ctrl;
+	unsigned int eof = 1, mss_mfs = 0;
+	u32 ctrl, lso_ctrl = 0, seq_ctrl = 0;
+
+	/* LSO */
+	if (skb_shinfo(skb)->gso_size != 0) {
+		if (IPPROTO_UDP == (((struct iphdr *)skb_network_header(skb))->protocol))
+			/* UDP - UFO */
+			lso_ctrl = MACB_LSO_UFO_ENABLE;
+		else
+			/* TCP - TSO */
+			lso_ctrl = MACB_LSO_TSO_ENABLE;
+	}
 
 	/* First, map non-paged data */
 	len = skb_headlen(skb);
+
+	/* first buffer length */
+	size = hdrlen;
+
 	offset = 0;
 	while (len) {
-		size = min(len, bp->max_tx_length);
 		entry = macb_tx_ring_wrap(tx_head);
 		tx_skb = &queue->tx_skb[entry];
 
@@ -1247,6 +1266,8 @@ static unsigned int macb_tx_map(struct macb *bp,
 		offset += size;
 		count++;
 		tx_head++;
+
+		size = min(len, bp->max_tx_length);
 	}
 
 	/* Then, map paged data from fragments */
@@ -1300,6 +1321,20 @@ static unsigned int macb_tx_map(struct macb *bp,
 	desc = &queue->tx_ring[entry];
 	desc->ctrl = ctrl;
 
+	if (lso_ctrl) {
+		if (lso_ctrl == MACB_LSO_UFO_ENABLE)
+			/* include header and FCS in value given to h/w */
+			mss_mfs = skb_shinfo(skb)->gso_size +
+					skb_transport_offset(skb) + 4;
+		else /* TSO */ {
+			mss_mfs = skb_shinfo(skb)->gso_size;
+			/* TCP Sequence Number Source Select
+			 * can be set only for TSO
+			 */
+			seq_ctrl = 0;
+		}
+	}
+
 	do {
 		i--;
 		entry = macb_tx_ring_wrap(i);
@@ -1314,6 +1349,16 @@ static unsigned int macb_tx_map(struct macb *bp,
 		if (unlikely(entry == (TX_RING_SIZE - 1)))
 			ctrl |= MACB_BIT(TX_WRAP);
 
+		/* First descriptor is header descriptor */
+		if (i == queue->tx_head) {
+			ctrl |= MACB_BF(TX_LSO, lso_ctrl);
+			ctrl |= MACB_BF(TX_TCP_SEQ_SRC, seq_ctrl);
+		} else
+			/* Only set MSS/MFS on payload descriptors
+			 * (second or later descriptor)
+			 */
+			ctrl |= MACB_BF(MSS_MFS, mss_mfs);
+
 		/* Set TX buffer descriptor */
 		macb_set_addr(desc, tx_skb->mapping);
 		/* desc->addr must be visible to hardware before clearing
@@ -1339,6 +1384,43 @@ static unsigned int macb_tx_map(struct macb *bp,
 	return 0;
 }
 
+static netdev_features_t macb_features_check(struct sk_buff *skb,
+					     struct net_device *dev,
+					     netdev_features_t features)
+{
+	unsigned int nr_frags, f;
+	unsigned int hdrlen;
+
+	/* Validate LSO compatibility */
+
+	/* there is only one buffer */
+	if (!skb_is_nonlinear(skb))
+		return features;
+
+	/* length of header */
+	hdrlen = skb_transport_offset(skb);
+	if (IPPROTO_TCP == (((struct iphdr *)skb_network_header(skb))->protocol))
+		hdrlen += tcp_hdrlen(skb);
+
+	/* For LSO:
+	 * When software supplies two or more payload buffers all payload buffers
+	 * apart from the last must be a multiple of 8 bytes in size.
+	 */
+	if (!IS_ALIGNED(skb_headlen(skb) - hdrlen, MACB_TX_LEN_ALIGN))
+		return features & ~MACB_NETIF_LSO;
+
+	nr_frags = skb_shinfo(skb)->nr_frags;
+	/* No need to check last fragment */
+	nr_frags--;
+	for (f = 0; f < nr_frags; f++) {
+		const skb_frag_t *frag = &skb_shinfo(skb)->frags[f];
+
+		if (!IS_ALIGNED(skb_frag_size(frag), MACB_TX_LEN_ALIGN))
+			return features & ~MACB_NETIF_LSO;
+	}
+	return features;
+}
+
 static inline int macb_clear_csum(struct sk_buff *skb)
 {
 	/* no change for packets without checksum offloading */
@@ -1363,7 +1445,27 @@ static int macb_start_xmit(struct sk_buff *skb, struct net_device *dev)
 	struct macb *bp = netdev_priv(dev);
 	struct macb_queue *queue = &bp->queues[queue_index];
 	unsigned long flags;
-	unsigned int count, nr_frags, frag_size, f;
+	unsigned int desc_cnt, nr_frags, frag_size, f;
+	unsigned int is_lso = 0, is_udp, hdrlen;
+
+	is_lso = (skb_shinfo(skb)->gso_size != 0);
+
+	if (is_lso) {
+		is_udp = (IPPROTO_UDP == (((struct iphdr *)skb_network_header(skb))->protocol));
+
+		/* length of headers */
+		if (is_udp)
+			/* only queue eth + ip headers separately for UDP */
+			hdrlen = skb_transport_offset(skb);
+		else
+			hdrlen = skb_transport_offset(skb) + tcp_hdrlen(skb);
+		if (skb_headlen(skb) < hdrlen) {
+			netdev_err(bp->dev, "Error - LSO headers fragmented!!!\n");
+			/* if this is required, would need to copy to single buffer */
+			return NETDEV_TX_BUSY;
+		}
+	} else
+		hdrlen = min(skb_headlen(skb), bp->max_tx_length);
 
 #if defined(DEBUG) && defined(VERBOSE_DEBUG)
 	netdev_vdbg(bp->dev,
@@ -1378,17 +1480,21 @@ static int macb_start_xmit(struct sk_buff *skb, struct net_device *dev)
 	 * socket buffer: skb fragments of jumbo frames may need to be
 	 * split into many buffer descriptors.
 	 */
-	count = DIV_ROUND_UP(skb_headlen(skb), bp->max_tx_length);
+	if (is_lso && (skb_headlen(skb) > hdrlen))
+		/* extra header descriptor if also payload in first buffer */
+		desc_cnt = DIV_ROUND_UP((skb_headlen(skb) - hdrlen), bp->max_tx_length) + 1;
+	else
+		desc_cnt = DIV_ROUND_UP(skb_headlen(skb), bp->max_tx_length);
 	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 += DIV_ROUND_UP(frag_size, bp->max_tx_length);
+		desc_cnt += DIV_ROUND_UP(frag_size, bp->max_tx_length);
 	}
 
 	spin_lock_irqsave(&bp->lock, flags);
 
 	/* This is a hard error, log it. */
-	if (CIRC_SPACE(queue->tx_head, queue->tx_tail, TX_RING_SIZE) < count) {
+	if (CIRC_SPACE(queue->tx_head, queue->tx_tail, TX_RING_SIZE) < desc_cnt) {
 		netif_stop_subqueue(dev, queue_index);
 		spin_unlock_irqrestore(&bp->lock, flags);
 		netdev_dbg(bp->dev, "tx_head = %u, tx_tail = %u\n",
@@ -1396,13 +1502,19 @@ static int macb_start_xmit(struct sk_buff *skb, struct net_device *dev)
 		return NETDEV_TX_BUSY;
 	}
 
+	if (is_lso) {
+		if (is_udp)
+			/* zero UDP checksum, not calculated by h/w for UFO */
+			udp_hdr(skb)->check = 0;
+	}
+
 	if (macb_clear_csum(skb)) {
 		dev_kfree_skb_any(skb);
 		goto unlock;
 	}
 
 	/* Map socket buffer for DMA transfer */
-	if (!macb_tx_map(bp, queue, skb)) {
+	if (!macb_tx_map(bp, queue, skb, hdrlen)) {
 		dev_kfree_skb_any(skb);
 		goto unlock;
 	}
@@ -2298,6 +2410,7 @@ static const struct net_device_ops macb_netdev_ops = {
 	.ndo_poll_controller	= macb_poll_controller,
 #endif
 	.ndo_set_features	= macb_set_features,
+	.ndo_features_check	= macb_features_check,
 };
 
 /* Configure peripheral capabilities according to device tree
@@ -2501,6 +2614,11 @@ static int macb_init(struct platform_device *pdev)
 
 	/* Set features */
 	dev->hw_features = NETIF_F_SG;
+
+	/* Check LSO capability */
+	if (GEM_BFEXT(PBUF_LSO, gem_readl(bp, DCFG6)))
+		dev->hw_features |= MACB_NETIF_LSO;
+
 	/* 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 | NETIF_F_RXCSUM;
diff --git a/drivers/net/ethernet/cadence/macb.h b/drivers/net/ethernet/cadence/macb.h
index 8bed4b5..534aded 100644
--- a/drivers/net/ethernet/cadence/macb.h
+++ b/drivers/net/ethernet/cadence/macb.h
@@ -382,6 +382,10 @@
 #define GEM_TX_PKT_BUFF_OFFSET			21
 #define GEM_TX_PKT_BUFF_SIZE			1
 
+/* Bitfields in DCFG6. */
+#define GEM_PBUF_LSO_OFFSET			27
+#define GEM_PBUF_LSO_SIZE			1
+
 /* Constants for CLK */
 #define MACB_CLK_DIV8				0
 #define MACB_CLK_DIV16				1
@@ -414,6 +418,10 @@
 #define MACB_CAPS_SG_DISABLED			0x40000000
 #define MACB_CAPS_MACB_IS_GEM			0x80000000
 
+/* LSO settings */
+#define MACB_LSO_UFO_ENABLE			0x01
+#define MACB_LSO_TSO_ENABLE			0x02
+
 /* Bit manipulation macros */
 #define MACB_BIT(name)					\
 	(1 << MACB_##name##_OFFSET)
@@ -545,6 +553,12 @@ struct macb_dma_desc {
 #define MACB_TX_LAST_SIZE			1
 #define MACB_TX_NOCRC_OFFSET			16
 #define MACB_TX_NOCRC_SIZE			1
+#define MACB_MSS_MFS_OFFSET			16
+#define MACB_MSS_MFS_SIZE			14
+#define MACB_TX_LSO_OFFSET			17
+#define MACB_TX_LSO_SIZE			2
+#define MACB_TX_TCP_SEQ_SRC_OFFSET		19
+#define MACB_TX_TCP_SEQ_SRC_SIZE		1
 #define MACB_TX_BUF_EXHAUSTED_OFFSET		27
 #define MACB_TX_BUF_EXHAUSTED_SIZE		1
 #define MACB_TX_UNDERRUN_OFFSET			28
-- 
2.4.5

Re: [PATCH v2] LSO feature added to Cadence GEM driver

[David Miller]

From: Rafal Ozieblo <rafalo@cadence.com>
Date: Tue, 25 Oct 2016 13:05:30 +0100

> New Cadence GEM hardware support Large Segment Offload (LSO):
> TCP segmentation offload (TSO) as well as UDP fragmentation
> offload (UFO). Support for those features was added to the driver.
> 
> Signed-off-by: Rafal Ozieblo <rafalo@cadence.com>

Patch does not apply cleanly to net-next, please respin.

Also please fix your Subject line, it should be of the form:

	[PATCH net-next v2] cadence: Add LSO support.

[PATCH net-next v3] cadence: Add LSO support.

[Rafal Ozieblo]

New Cadence GEM hardware support Large Segment Offload (LSO):
TCP segmentation offload (TSO) as well as UDP fragmentation
offload (UFO). Support for those features was added to the driver.

Signed-off-by: Rafal Ozieblo <rafalo@cadence.com>
---
Changed in v2:
macb_lso_check_compatibility() changed to macb_features_check()
(with little modifications) and bind to .ndo_features_check.
(after Eric Dumazet suggestion)
---
Changed in v3:
Respin to net-next.
---
 drivers/net/ethernet/cadence/macb.c | 142 +++++++++++++++++++++++++++++++++---
 drivers/net/ethernet/cadence/macb.h |  14 ++++
 2 files changed, 144 insertions(+), 12 deletions(-)

diff --git a/drivers/net/ethernet/cadence/macb.c b/drivers/net/ethernet/cadence/macb.c
index e1847ce..1eeaa4b 100644
--- a/drivers/net/ethernet/cadence/macb.c
+++ b/drivers/net/ethernet/cadence/macb.c
@@ -32,7 +32,9 @@
 #include <linux/of_gpio.h>
 #include <linux/of_mdio.h>
 #include <linux/of_net.h>
-
+#include <linux/ip.h>
+#include <linux/udp.h>
+#include <linux/tcp.h>
 #include "macb.h"
 
 #define MACB_RX_BUFFER_SIZE	128
@@ -60,10 +62,13 @@
 					| 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))
+/* Max length of transmit frame must be a multiple of 8 bytes */
+#define MACB_TX_LEN_ALIGN	8
+#define MACB_MAX_TX_LEN		((unsigned int)((1 << MACB_TX_FRMLEN_SIZE) - 1) & ~((unsigned int)(MACB_TX_LEN_ALIGN - 1)))
+#define GEM_MAX_TX_LEN		((unsigned int)((1 << GEM_TX_FRMLEN_SIZE) - 1) & ~((unsigned int)(MACB_TX_LEN_ALIGN - 1)))
 
 #define GEM_MTU_MIN_SIZE	ETH_MIN_MTU
+#define MACB_NETIF_LSO		(NETIF_F_TSO | NETIF_F_UFO)
 
 #define MACB_WOL_HAS_MAGIC_PACKET	(0x1 << 0)
 #define MACB_WOL_ENABLED		(0x1 << 1)
@@ -1223,7 +1228,8 @@ static void macb_poll_controller(struct net_device *dev)
 
 static unsigned int macb_tx_map(struct macb *bp,
 				struct macb_queue *queue,
-				struct sk_buff *skb)
+				struct sk_buff *skb,
+				unsigned int hdrlen)
 {
 	dma_addr_t mapping;
 	unsigned int len, entry, i, tx_head = queue->tx_head;
@@ -1231,14 +1237,27 @@ static unsigned int macb_tx_map(struct macb *bp,
 	struct macb_dma_desc *desc;
 	unsigned int offset, size, count = 0;
 	unsigned int f, nr_frags = skb_shinfo(skb)->nr_frags;
-	unsigned int eof = 1;
-	u32 ctrl;
+	unsigned int eof = 1, mss_mfs = 0;
+	u32 ctrl, lso_ctrl = 0, seq_ctrl = 0;
+
+	/* LSO */
+	if (skb_shinfo(skb)->gso_size != 0) {
+		if (IPPROTO_UDP == (((struct iphdr *)skb_network_header(skb))->protocol))
+			/* UDP - UFO */
+			lso_ctrl = MACB_LSO_UFO_ENABLE;
+		else
+			/* TCP - TSO */
+			lso_ctrl = MACB_LSO_TSO_ENABLE;
+	}
 
 	/* First, map non-paged data */
 	len = skb_headlen(skb);
+
+	/* first buffer length */
+	size = hdrlen;
+
 	offset = 0;
 	while (len) {
-		size = min(len, bp->max_tx_length);
 		entry = macb_tx_ring_wrap(bp, tx_head);
 		tx_skb = &queue->tx_skb[entry];
 
@@ -1258,6 +1277,8 @@ static unsigned int macb_tx_map(struct macb *bp,
 		offset += size;
 		count++;
 		tx_head++;
+
+		size = min(len, bp->max_tx_length);
 	}
 
 	/* Then, map paged data from fragments */
@@ -1311,6 +1332,20 @@ static unsigned int macb_tx_map(struct macb *bp,
 	desc = &queue->tx_ring[entry];
 	desc->ctrl = ctrl;
 
+	if (lso_ctrl) {
+		if (lso_ctrl == MACB_LSO_UFO_ENABLE)
+			/* include header and FCS in value given to h/w */
+			mss_mfs = skb_shinfo(skb)->gso_size +
+					skb_transport_offset(skb) + 4;
+		else /* TSO */ {
+			mss_mfs = skb_shinfo(skb)->gso_size;
+			/* TCP Sequence Number Source Select
+			 * can be set only for TSO
+			 */
+			seq_ctrl = 0;
+		}
+	}
+
 	do {
 		i--;
 		entry = macb_tx_ring_wrap(bp, i);
@@ -1325,6 +1360,16 @@ static unsigned int macb_tx_map(struct macb *bp,
 		if (unlikely(entry == (bp->tx_ring_size - 1)))
 			ctrl |= MACB_BIT(TX_WRAP);
 
+		/* First descriptor is header descriptor */
+		if (i == queue->tx_head) {
+			ctrl |= MACB_BF(TX_LSO, lso_ctrl);
+			ctrl |= MACB_BF(TX_TCP_SEQ_SRC, seq_ctrl);
+		} else
+			/* Only set MSS/MFS on payload descriptors
+			 * (second or later descriptor)
+			 */
+			ctrl |= MACB_BF(MSS_MFS, mss_mfs);
+
 		/* Set TX buffer descriptor */
 		macb_set_addr(desc, tx_skb->mapping);
 		/* desc->addr must be visible to hardware before clearing
@@ -1350,6 +1395,43 @@ static unsigned int macb_tx_map(struct macb *bp,
 	return 0;
 }
 
+static netdev_features_t macb_features_check(struct sk_buff *skb,
+					     struct net_device *dev,
+					     netdev_features_t features)
+{
+	unsigned int nr_frags, f;
+	unsigned int hdrlen;
+
+	/* Validate LSO compatibility */
+
+	/* there is only one buffer */
+	if (!skb_is_nonlinear(skb))
+		return features;
+
+	/* length of header */
+	hdrlen = skb_transport_offset(skb);
+	if (IPPROTO_TCP == (((struct iphdr *)skb_network_header(skb))->protocol))
+		hdrlen += tcp_hdrlen(skb);
+
+	/* For LSO:
+	 * When software supplies two or more payload buffers all payload buffers
+	 * apart from the last must be a multiple of 8 bytes in size.
+	 */
+	if (!IS_ALIGNED(skb_headlen(skb) - hdrlen, MACB_TX_LEN_ALIGN))
+		return features & ~MACB_NETIF_LSO;
+
+	nr_frags = skb_shinfo(skb)->nr_frags;
+	/* No need to check last fragment */
+	nr_frags--;
+	for (f = 0; f < nr_frags; f++) {
+		const skb_frag_t *frag = &skb_shinfo(skb)->frags[f];
+
+		if (!IS_ALIGNED(skb_frag_size(frag), MACB_TX_LEN_ALIGN))
+			return features & ~MACB_NETIF_LSO;
+	}
+	return features;
+}
+
 static inline int macb_clear_csum(struct sk_buff *skb)
 {
 	/* no change for packets without checksum offloading */
@@ -1374,7 +1456,27 @@ static int macb_start_xmit(struct sk_buff *skb, struct net_device *dev)
 	struct macb *bp = netdev_priv(dev);
 	struct macb_queue *queue = &bp->queues[queue_index];
 	unsigned long flags;
-	unsigned int count, nr_frags, frag_size, f;
+	unsigned int desc_cnt, nr_frags, frag_size, f;
+	unsigned int is_lso = 0, is_udp, hdrlen;
+
+	is_lso = (skb_shinfo(skb)->gso_size != 0);
+
+	if (is_lso) {
+		is_udp = (IPPROTO_UDP == (((struct iphdr *)skb_network_header(skb))->protocol));
+
+		/* length of headers */
+		if (is_udp)
+			/* only queue eth + ip headers separately for UDP */
+			hdrlen = skb_transport_offset(skb);
+		else
+			hdrlen = skb_transport_offset(skb) + tcp_hdrlen(skb);
+		if (skb_headlen(skb) < hdrlen) {
+			netdev_err(bp->dev, "Error - LSO headers fragmented!!!\n");
+			/* if this is required, would need to copy to single buffer */
+			return NETDEV_TX_BUSY;
+		}
+	} else
+		hdrlen = min(skb_headlen(skb), bp->max_tx_length);
 
 #if defined(DEBUG) && defined(VERBOSE_DEBUG)
 	netdev_vdbg(bp->dev,
@@ -1389,18 +1491,22 @@ static int macb_start_xmit(struct sk_buff *skb, struct net_device *dev)
 	 * socket buffer: skb fragments of jumbo frames may need to be
 	 * split into many buffer descriptors.
 	 */
-	count = DIV_ROUND_UP(skb_headlen(skb), bp->max_tx_length);
+	if (is_lso && (skb_headlen(skb) > hdrlen))
+		/* extra header descriptor if also payload in first buffer */
+		desc_cnt = DIV_ROUND_UP((skb_headlen(skb) - hdrlen), bp->max_tx_length) + 1;
+	else
+		desc_cnt = DIV_ROUND_UP(skb_headlen(skb), bp->max_tx_length);
 	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 += DIV_ROUND_UP(frag_size, bp->max_tx_length);
+		desc_cnt += DIV_ROUND_UP(frag_size, bp->max_tx_length);
 	}
 
 	spin_lock_irqsave(&bp->lock, flags);
 
 	/* This is a hard error, log it. */
 	if (CIRC_SPACE(queue->tx_head, queue->tx_tail,
-		       bp->tx_ring_size) < count) {
+		       bp->tx_ring_size) < desc_cnt) {
 		netif_stop_subqueue(dev, queue_index);
 		spin_unlock_irqrestore(&bp->lock, flags);
 		netdev_dbg(bp->dev, "tx_head = %u, tx_tail = %u\n",
@@ -1408,13 +1514,19 @@ static int macb_start_xmit(struct sk_buff *skb, struct net_device *dev)
 		return NETDEV_TX_BUSY;
 	}
 
+	if (is_lso) {
+		if (is_udp)
+			/* zero UDP checksum, not calculated by h/w for UFO */
+			udp_hdr(skb)->check = 0;
+	}
+
 	if (macb_clear_csum(skb)) {
 		dev_kfree_skb_any(skb);
 		goto unlock;
 	}
 
 	/* Map socket buffer for DMA transfer */
-	if (!macb_tx_map(bp, queue, skb)) {
+	if (!macb_tx_map(bp, queue, skb, hdrlen)) {
 		dev_kfree_skb_any(skb);
 		goto unlock;
 	}
@@ -2354,6 +2466,7 @@ static const struct net_device_ops macb_netdev_ops = {
 	.ndo_poll_controller	= macb_poll_controller,
 #endif
 	.ndo_set_features	= macb_set_features,
+	.ndo_features_check	= macb_features_check,
 };
 
 /* Configure peripheral capabilities according to device tree
@@ -2560,6 +2673,11 @@ static int macb_init(struct platform_device *pdev)
 
 	/* Set features */
 	dev->hw_features = NETIF_F_SG;
+
+	/* Check LSO capability */
+	if (GEM_BFEXT(PBUF_LSO, gem_readl(bp, DCFG6)))
+		dev->hw_features |= MACB_NETIF_LSO;
+
 	/* 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 | NETIF_F_RXCSUM;
diff --git a/drivers/net/ethernet/cadence/macb.h b/drivers/net/ethernet/cadence/macb.h
index 1216950..d67adad 100644
--- a/drivers/net/ethernet/cadence/macb.h
+++ b/drivers/net/ethernet/cadence/macb.h
@@ -382,6 +382,10 @@
 #define GEM_TX_PKT_BUFF_OFFSET			21
 #define GEM_TX_PKT_BUFF_SIZE			1
 
+/* Bitfields in DCFG6. */
+#define GEM_PBUF_LSO_OFFSET			27
+#define GEM_PBUF_LSO_SIZE			1
+
 /* Constants for CLK */
 #define MACB_CLK_DIV8				0
 #define MACB_CLK_DIV16				1
@@ -414,6 +418,10 @@
 #define MACB_CAPS_SG_DISABLED			0x40000000
 #define MACB_CAPS_MACB_IS_GEM			0x80000000
 
+/* LSO settings */
+#define MACB_LSO_UFO_ENABLE			0x01
+#define MACB_LSO_TSO_ENABLE			0x02
+
 /* Bit manipulation macros */
 #define MACB_BIT(name)					\
 	(1 << MACB_##name##_OFFSET)
@@ -545,6 +553,12 @@ struct macb_dma_desc {
 #define MACB_TX_LAST_SIZE			1
 #define MACB_TX_NOCRC_OFFSET			16
 #define MACB_TX_NOCRC_SIZE			1
+#define MACB_MSS_MFS_OFFSET			16
+#define MACB_MSS_MFS_SIZE			14
+#define MACB_TX_LSO_OFFSET			17
+#define MACB_TX_LSO_SIZE			2
+#define MACB_TX_TCP_SEQ_SRC_OFFSET		19
+#define MACB_TX_TCP_SEQ_SRC_SIZE		1
 #define MACB_TX_BUF_EXHAUSTED_OFFSET		27
 #define MACB_TX_BUF_EXHAUSTED_SIZE		1
 #define MACB_TX_UNDERRUN_OFFSET			28
-- 
2.4.5

Re: [PATCH net-next v3] cadence: Add LSO support.

[David Miller]

From: Rafal Ozieblo <rafalo@cadence.com>
Date: Fri, 4 Nov 2016 11:40:18 +0000

> +		if (IPPROTO_UDP == (((struct iphdr *)skb_network_header(skb))->protocol))

This is simply "ip_hdr(skb)->protocol", please use it everywhere you
have this ugly cast thing in this change.

Thanks.

[PATCH net-next v4] cadence: Add LSO support.

[Rafal Ozieblo]

New Cadence GEM hardware support Large Segment Offload (LSO):
TCP segmentation offload (TSO) as well as UDP fragmentation
offload (UFO). Support for those features was added to the driver.

Signed-off-by: Rafal Ozieblo <rafalo@cadence.com>
---
Changed in v2:
macb_lso_check_compatibility() changed to macb_features_check()
(with little modifications) and bind to .ndo_features_check.
(after Eric Dumazet suggestion)
---
Changed in v3:
Respin to net-next.
---
Changed in v4:
(struct iphdr*)skb_network_header(skb) changed to ip_hdr(skb)
---
 drivers/net/ethernet/cadence/macb.c | 142 +++++++++++++++++++++++++++++++++---
 drivers/net/ethernet/cadence/macb.h |  14 ++++
 2 files changed, 144 insertions(+), 12 deletions(-)

diff --git a/drivers/net/ethernet/cadence/macb.c b/drivers/net/ethernet/cadence/macb.c
index e1847ce..2a46aae 100644
--- a/drivers/net/ethernet/cadence/macb.c
+++ b/drivers/net/ethernet/cadence/macb.c
@@ -32,7 +32,9 @@
 #include <linux/of_gpio.h>
 #include <linux/of_mdio.h>
 #include <linux/of_net.h>
-
+#include <linux/ip.h>
+#include <linux/udp.h>
+#include <linux/tcp.h>
 #include "macb.h"
 
 #define MACB_RX_BUFFER_SIZE	128
@@ -60,10 +62,13 @@
 					| 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))
+/* Max length of transmit frame must be a multiple of 8 bytes */
+#define MACB_TX_LEN_ALIGN	8
+#define MACB_MAX_TX_LEN		((unsigned int)((1 << MACB_TX_FRMLEN_SIZE) - 1) & ~((unsigned int)(MACB_TX_LEN_ALIGN - 1)))
+#define GEM_MAX_TX_LEN		((unsigned int)((1 << GEM_TX_FRMLEN_SIZE) - 1) & ~((unsigned int)(MACB_TX_LEN_ALIGN - 1)))
 
 #define GEM_MTU_MIN_SIZE	ETH_MIN_MTU
+#define MACB_NETIF_LSO		(NETIF_F_TSO | NETIF_F_UFO)
 
 #define MACB_WOL_HAS_MAGIC_PACKET	(0x1 << 0)
 #define MACB_WOL_ENABLED		(0x1 << 1)
@@ -1223,7 +1228,8 @@ static void macb_poll_controller(struct net_device *dev)
 
 static unsigned int macb_tx_map(struct macb *bp,
 				struct macb_queue *queue,
-				struct sk_buff *skb)
+				struct sk_buff *skb,
+				unsigned int hdrlen)
 {
 	dma_addr_t mapping;
 	unsigned int len, entry, i, tx_head = queue->tx_head;
@@ -1231,14 +1237,27 @@ static unsigned int macb_tx_map(struct macb *bp,
 	struct macb_dma_desc *desc;
 	unsigned int offset, size, count = 0;
 	unsigned int f, nr_frags = skb_shinfo(skb)->nr_frags;
-	unsigned int eof = 1;
-	u32 ctrl;
+	unsigned int eof = 1, mss_mfs = 0;
+	u32 ctrl, lso_ctrl = 0, seq_ctrl = 0;
+
+	/* LSO */
+	if (skb_shinfo(skb)->gso_size != 0) {
+		if (IPPROTO_UDP == (ip_hdr(skb)->protocol))
+			/* UDP - UFO */
+			lso_ctrl = MACB_LSO_UFO_ENABLE;
+		else
+			/* TCP - TSO */
+			lso_ctrl = MACB_LSO_TSO_ENABLE;
+	}
 
 	/* First, map non-paged data */
 	len = skb_headlen(skb);
+
+	/* first buffer length */
+	size = hdrlen;
+
 	offset = 0;
 	while (len) {
-		size = min(len, bp->max_tx_length);
 		entry = macb_tx_ring_wrap(bp, tx_head);
 		tx_skb = &queue->tx_skb[entry];
 
@@ -1258,6 +1277,8 @@ static unsigned int macb_tx_map(struct macb *bp,
 		offset += size;
 		count++;
 		tx_head++;
+
+		size = min(len, bp->max_tx_length);
 	}
 
 	/* Then, map paged data from fragments */
@@ -1311,6 +1332,20 @@ static unsigned int macb_tx_map(struct macb *bp,
 	desc = &queue->tx_ring[entry];
 	desc->ctrl = ctrl;
 
+	if (lso_ctrl) {
+		if (lso_ctrl == MACB_LSO_UFO_ENABLE)
+			/* include header and FCS in value given to h/w */
+			mss_mfs = skb_shinfo(skb)->gso_size +
+					skb_transport_offset(skb) + 4;
+		else /* TSO */ {
+			mss_mfs = skb_shinfo(skb)->gso_size;
+			/* TCP Sequence Number Source Select
+			 * can be set only for TSO
+			 */
+			seq_ctrl = 0;
+		}
+	}
+
 	do {
 		i--;
 		entry = macb_tx_ring_wrap(bp, i);
@@ -1325,6 +1360,16 @@ static unsigned int macb_tx_map(struct macb *bp,
 		if (unlikely(entry == (bp->tx_ring_size - 1)))
 			ctrl |= MACB_BIT(TX_WRAP);
 
+		/* First descriptor is header descriptor */
+		if (i == queue->tx_head) {
+			ctrl |= MACB_BF(TX_LSO, lso_ctrl);
+			ctrl |= MACB_BF(TX_TCP_SEQ_SRC, seq_ctrl);
+		} else
+			/* Only set MSS/MFS on payload descriptors
+			 * (second or later descriptor)
+			 */
+			ctrl |= MACB_BF(MSS_MFS, mss_mfs);
+
 		/* Set TX buffer descriptor */
 		macb_set_addr(desc, tx_skb->mapping);
 		/* desc->addr must be visible to hardware before clearing
@@ -1350,6 +1395,43 @@ static unsigned int macb_tx_map(struct macb *bp,
 	return 0;
 }
 
+static netdev_features_t macb_features_check(struct sk_buff *skb,
+					     struct net_device *dev,
+					     netdev_features_t features)
+{
+	unsigned int nr_frags, f;
+	unsigned int hdrlen;
+
+	/* Validate LSO compatibility */
+
+	/* there is only one buffer */
+	if (!skb_is_nonlinear(skb))
+		return features;
+
+	/* length of header */
+	hdrlen = skb_transport_offset(skb);
+	if (IPPROTO_TCP == (ip_hdr(skb)->protocol))
+		hdrlen += tcp_hdrlen(skb);
+
+	/* For LSO:
+	 * When software supplies two or more payload buffers all payload buffers
+	 * apart from the last must be a multiple of 8 bytes in size.
+	 */
+	if (!IS_ALIGNED(skb_headlen(skb) - hdrlen, MACB_TX_LEN_ALIGN))
+		return features & ~MACB_NETIF_LSO;
+
+	nr_frags = skb_shinfo(skb)->nr_frags;
+	/* No need to check last fragment */
+	nr_frags--;
+	for (f = 0; f < nr_frags; f++) {
+		const skb_frag_t *frag = &skb_shinfo(skb)->frags[f];
+
+		if (!IS_ALIGNED(skb_frag_size(frag), MACB_TX_LEN_ALIGN))
+			return features & ~MACB_NETIF_LSO;
+	}
+	return features;
+}
+
 static inline int macb_clear_csum(struct sk_buff *skb)
 {
 	/* no change for packets without checksum offloading */
@@ -1374,7 +1456,27 @@ static int macb_start_xmit(struct sk_buff *skb, struct net_device *dev)
 	struct macb *bp = netdev_priv(dev);
 	struct macb_queue *queue = &bp->queues[queue_index];
 	unsigned long flags;
-	unsigned int count, nr_frags, frag_size, f;
+	unsigned int desc_cnt, nr_frags, frag_size, f;
+	unsigned int is_lso = 0, is_udp, hdrlen;
+
+	is_lso = (skb_shinfo(skb)->gso_size != 0);
+
+	if (is_lso) {
+		is_udp = (IPPROTO_UDP == (ip_hdr(skb)->protocol));
+
+		/* length of headers */
+		if (is_udp)
+			/* only queue eth + ip headers separately for UDP */
+			hdrlen = skb_transport_offset(skb);
+		else
+			hdrlen = skb_transport_offset(skb) + tcp_hdrlen(skb);
+		if (skb_headlen(skb) < hdrlen) {
+			netdev_err(bp->dev, "Error - LSO headers fragmented!!!\n");
+			/* if this is required, would need to copy to single buffer */
+			return NETDEV_TX_BUSY;
+		}
+	} else
+		hdrlen = min(skb_headlen(skb), bp->max_tx_length);
 
 #if defined(DEBUG) && defined(VERBOSE_DEBUG)
 	netdev_vdbg(bp->dev,
@@ -1389,18 +1491,22 @@ static int macb_start_xmit(struct sk_buff *skb, struct net_device *dev)
 	 * socket buffer: skb fragments of jumbo frames may need to be
 	 * split into many buffer descriptors.
 	 */
-	count = DIV_ROUND_UP(skb_headlen(skb), bp->max_tx_length);
+	if (is_lso && (skb_headlen(skb) > hdrlen))
+		/* extra header descriptor if also payload in first buffer */
+		desc_cnt = DIV_ROUND_UP((skb_headlen(skb) - hdrlen), bp->max_tx_length) + 1;
+	else
+		desc_cnt = DIV_ROUND_UP(skb_headlen(skb), bp->max_tx_length);
 	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 += DIV_ROUND_UP(frag_size, bp->max_tx_length);
+		desc_cnt += DIV_ROUND_UP(frag_size, bp->max_tx_length);
 	}
 
 	spin_lock_irqsave(&bp->lock, flags);
 
 	/* This is a hard error, log it. */
 	if (CIRC_SPACE(queue->tx_head, queue->tx_tail,
-		       bp->tx_ring_size) < count) {
+		       bp->tx_ring_size) < desc_cnt) {
 		netif_stop_subqueue(dev, queue_index);
 		spin_unlock_irqrestore(&bp->lock, flags);
 		netdev_dbg(bp->dev, "tx_head = %u, tx_tail = %u\n",
@@ -1408,13 +1514,19 @@ static int macb_start_xmit(struct sk_buff *skb, struct net_device *dev)
 		return NETDEV_TX_BUSY;
 	}
 
+	if (is_lso) {
+		if (is_udp)
+			/* zero UDP checksum, not calculated by h/w for UFO */
+			udp_hdr(skb)->check = 0;
+	}
+
 	if (macb_clear_csum(skb)) {
 		dev_kfree_skb_any(skb);
 		goto unlock;
 	}
 
 	/* Map socket buffer for DMA transfer */
-	if (!macb_tx_map(bp, queue, skb)) {
+	if (!macb_tx_map(bp, queue, skb, hdrlen)) {
 		dev_kfree_skb_any(skb);
 		goto unlock;
 	}
@@ -2354,6 +2466,7 @@ static const struct net_device_ops macb_netdev_ops = {
 	.ndo_poll_controller	= macb_poll_controller,
 #endif
 	.ndo_set_features	= macb_set_features,
+	.ndo_features_check	= macb_features_check,
 };
 
 /* Configure peripheral capabilities according to device tree
@@ -2560,6 +2673,11 @@ static int macb_init(struct platform_device *pdev)
 
 	/* Set features */
 	dev->hw_features = NETIF_F_SG;
+
+	/* Check LSO capability */
+	if (GEM_BFEXT(PBUF_LSO, gem_readl(bp, DCFG6)))
+		dev->hw_features |= MACB_NETIF_LSO;
+
 	/* 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 | NETIF_F_RXCSUM;
diff --git a/drivers/net/ethernet/cadence/macb.h b/drivers/net/ethernet/cadence/macb.h
index 1216950..d67adad 100644
--- a/drivers/net/ethernet/cadence/macb.h
+++ b/drivers/net/ethernet/cadence/macb.h
@@ -382,6 +382,10 @@
 #define GEM_TX_PKT_BUFF_OFFSET			21
 #define GEM_TX_PKT_BUFF_SIZE			1
 
+/* Bitfields in DCFG6. */
+#define GEM_PBUF_LSO_OFFSET			27
+#define GEM_PBUF_LSO_SIZE			1
+
 /* Constants for CLK */
 #define MACB_CLK_DIV8				0
 #define MACB_CLK_DIV16				1
@@ -414,6 +418,10 @@
 #define MACB_CAPS_SG_DISABLED			0x40000000
 #define MACB_CAPS_MACB_IS_GEM			0x80000000
 
+/* LSO settings */
+#define MACB_LSO_UFO_ENABLE			0x01
+#define MACB_LSO_TSO_ENABLE			0x02
+
 /* Bit manipulation macros */
 #define MACB_BIT(name)					\
 	(1 << MACB_##name##_OFFSET)
@@ -545,6 +553,12 @@ struct macb_dma_desc {
 #define MACB_TX_LAST_SIZE			1
 #define MACB_TX_NOCRC_OFFSET			16
 #define MACB_TX_NOCRC_SIZE			1
+#define MACB_MSS_MFS_OFFSET			16
+#define MACB_MSS_MFS_SIZE			14
+#define MACB_TX_LSO_OFFSET			17
+#define MACB_TX_LSO_SIZE			2
+#define MACB_TX_TCP_SEQ_SRC_OFFSET		19
+#define MACB_TX_TCP_SEQ_SRC_SIZE		1
 #define MACB_TX_BUF_EXHAUSTED_OFFSET		27
 #define MACB_TX_BUF_EXHAUSTED_SIZE		1
 #define MACB_TX_UNDERRUN_OFFSET			28
-- 
2.4.5

Re: [PATCH net-next v4] cadence: Add LSO support.

[Florian Fainelli]

On 11/08/2016 05:41 AM, Rafal Ozieblo wrote:
> New Cadence GEM hardware support Large Segment Offload (LSO):
> TCP segmentation offload (TSO) as well as UDP fragmentation
> offload (UFO). Support for those features was added to the driver.
> 
> Signed-off-by: Rafal Ozieblo <rafalo@cadence.com>
> ---

> -#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))
> +/* Max length of transmit frame must be a multiple of 8 bytes */
> +#define MACB_TX_LEN_ALIGN	8
> +#define MACB_MAX_TX_LEN		((unsigned int)((1 << MACB_TX_FRMLEN_SIZE) - 1) & ~((unsigned int)(MACB_TX_LEN_ALIGN - 1)))
> +#define GEM_MAX_TX_LEN		((unsigned int)((1 << GEM_TX_FRMLEN_SIZE) - 1) & ~((unsigned int)(MACB_TX_LEN_ALIGN - 1)))
>  
>  #define GEM_MTU_MIN_SIZE	ETH_MIN_MTU
> +#define MACB_NETIF_LSO		(NETIF_F_TSO | NETIF_F_UFO)

Not a huge fan of this definition, since it is always used in conjuction
with netdev_features_t, having it expanded all the time is kind of nicer
for the reader, but this is just personal preference here.

>  
>  #define MACB_WOL_HAS_MAGIC_PACKET	(0x1 << 0)
>  #define MACB_WOL_ENABLED		(0x1 << 1)
> @@ -1223,7 +1228,8 @@ static void macb_poll_controller(struct net_device *dev)
>  
>  static unsigned int macb_tx_map(struct macb *bp,
>  				struct macb_queue *queue,
> -				struct sk_buff *skb)
> +				struct sk_buff *skb,
> +				unsigned int hdrlen)
>  {
>  	dma_addr_t mapping;
>  	unsigned int len, entry, i, tx_head = queue->tx_head;
> @@ -1231,14 +1237,27 @@ static unsigned int macb_tx_map(struct macb *bp,
>  	struct macb_dma_desc *desc;
>  	unsigned int offset, size, count = 0;
>  	unsigned int f, nr_frags = skb_shinfo(skb)->nr_frags;
> -	unsigned int eof = 1;
> -	u32 ctrl;
> +	unsigned int eof = 1, mss_mfs = 0;
> +	u32 ctrl, lso_ctrl = 0, seq_ctrl = 0;
> +
> +	/* LSO */
> +	if (skb_shinfo(skb)->gso_size != 0) {
> +		if (IPPROTO_UDP == (ip_hdr(skb)->protocol))

Most checks are usually done the other way with the left and right
member swapped.

> +			/* UDP - UFO */
> +			lso_ctrl = MACB_LSO_UFO_ENABLE;
> +		else
> +			/* TCP - TSO */
> +			lso_ctrl = MACB_LSO_TSO_ENABLE;
> +	}

>  
>  	/* Then, map paged data from fragments */
> @@ -1311,6 +1332,20 @@ static unsigned int macb_tx_map(struct macb *bp,
>  	desc = &queue->tx_ring[entry];
>  	desc->ctrl = ctrl;
>  
> +	if (lso_ctrl) {
> +		if (lso_ctrl == MACB_LSO_UFO_ENABLE)
> +			/* include header and FCS in value given to h/w */
> +			mss_mfs = skb_shinfo(skb)->gso_size +
> +					skb_transport_offset(skb) + 4;

ETH_FCS_LEN instead of 4?


> +static netdev_features_t macb_features_check(struct sk_buff *skb,
> +					     struct net_device *dev,
> +					     netdev_features_t features)
> +{
> +	unsigned int nr_frags, f;
> +	unsigned int hdrlen;
> +
> +	/* Validate LSO compatibility */
> +
> +	/* there is only one buffer */
> +	if (!skb_is_nonlinear(skb))
> +		return features;
> +
> +	/* length of header */
> +	hdrlen = skb_transport_offset(skb);
> +	if (IPPROTO_TCP == (ip_hdr(skb)->protocol))
> +		hdrlen += tcp_hdrlen(skb);

Same here, please reverse the left and right members, no need for
parenthesis aground ip_hdr(skb)->protocol.

> +
> +	/* For LSO:
> +	 * When software supplies two or more payload buffers all payload buffers
> +	 * apart from the last must be a multiple of 8 bytes in size.
> +	 */
> +	if (!IS_ALIGNED(skb_headlen(skb) - hdrlen, MACB_TX_LEN_ALIGN))
> +		return features & ~MACB_NETIF_LSO;
> +
> +	nr_frags = skb_shinfo(skb)->nr_frags;
> +	/* No need to check last fragment */
> +	nr_frags--;
> +	for (f = 0; f < nr_frags; f++) {
> +		const skb_frag_t *frag = &skb_shinfo(skb)->frags[f];
> +
> +		if (!IS_ALIGNED(skb_frag_size(frag), MACB_TX_LEN_ALIGN))
> +			return features & ~MACB_NETIF_LSO;
> +	}
> +	return features;
> +}
> +
>  static inline int macb_clear_csum(struct sk_buff *skb)
>  {
>  	/* no change for packets without checksum offloading */
> @@ -1374,7 +1456,27 @@ static int macb_start_xmit(struct sk_buff *skb, struct net_device *dev)
>  	struct macb *bp = netdev_priv(dev);
>  	struct macb_queue *queue = &bp->queues[queue_index];
>  	unsigned long flags;
> -	unsigned int count, nr_frags, frag_size, f;
> +	unsigned int desc_cnt, nr_frags, frag_size, f;
> +	unsigned int is_lso = 0, is_udp, hdrlen;
> +
> +	is_lso = (skb_shinfo(skb)->gso_size != 0);
> +
> +	if (is_lso) {
> +		is_udp = (IPPROTO_UDP == (ip_hdr(skb)->protocol));

Same here, and you may want to declare is_udp as boolean and do this:

		is_udp = !!(ip_hdr(skb)->protocl == IPPROTO_UDP);

> +
> +		/* length of headers */
> +		if (is_udp)
> +			/* only queue eth + ip headers separately for UDP */
> +			hdrlen = skb_transport_offset(skb);
> +		else
> +			hdrlen = skb_transport_offset(skb) + tcp_hdrlen(skb);
> +		if (skb_headlen(skb) < hdrlen) {
> +			netdev_err(bp->dev, "Error - LSO headers fragmented!!!\n");
> +			/* if this is required, would need to copy to single buffer */
> +			return NETDEV_TX_BUSY;
> +		}

>  
> +	if (is_lso) {
> +		if (is_udp)
> +			/* zero UDP checksum, not calculated by h/w for UFO */
> +			udp_hdr(skb)->check = 0;

is_udp is only set when (is_lso) is checked, so the two conditions are
redundant, just checking is_udp should be enough?
-- 
Florian

[PATCH net-next v5]] cadence: Add LSO support.

[Rafal Ozieblo]

New Cadence GEM hardware support Large Segment Offload (LSO):
TCP segmentation offload (TSO) as well as UDP fragmentation
offload (UFO). Support for those features was added to the driver.

Signed-off-by: Rafal Ozieblo <rafalo@cadence.com>
---
Changed in v2:
macb_lso_check_compatibility() changed to macb_features_check()
(with little modifications) and bind to .ndo_features_check.
(after Eric Dumazet suggestion)
---
Changed in v3:
Respin to net-next.
---
Changed in v4:
(struct iphdr*)skb_network_header(skb) changed to ip_hdr(skb)
---
Changed in v5:
Changes after Florian Fainelli comments
---
 drivers/net/ethernet/cadence/macb.c | 142 +++++++++++++++++++++++++++++++++---
 drivers/net/ethernet/cadence/macb.h |  14 ++++
 2 files changed, 144 insertions(+), 12 deletions(-)

diff --git a/drivers/net/ethernet/cadence/macb.c b/drivers/net/ethernet/cadence/macb.c
index e1847ce..dd38ef7 100644
--- a/drivers/net/ethernet/cadence/macb.c
+++ b/drivers/net/ethernet/cadence/macb.c
@@ -32,7 +32,9 @@
 #include <linux/of_gpio.h>
 #include <linux/of_mdio.h>
 #include <linux/of_net.h>
-
+#include <linux/ip.h>
+#include <linux/udp.h>
+#include <linux/tcp.h>
 #include "macb.h"
 
 #define MACB_RX_BUFFER_SIZE	128
@@ -60,10 +62,13 @@
 					| 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))
+/* Max length of transmit frame must be a multiple of 8 bytes */
+#define MACB_TX_LEN_ALIGN	8
+#define MACB_MAX_TX_LEN		((unsigned int)((1 << MACB_TX_FRMLEN_SIZE) - 1) & ~((unsigned int)(MACB_TX_LEN_ALIGN - 1)))
+#define GEM_MAX_TX_LEN		((unsigned int)((1 << GEM_TX_FRMLEN_SIZE) - 1) & ~((unsigned int)(MACB_TX_LEN_ALIGN - 1)))
 
 #define GEM_MTU_MIN_SIZE	ETH_MIN_MTU
+#define MACB_NETIF_LSO		(NETIF_F_TSO | NETIF_F_UFO)
 
 #define MACB_WOL_HAS_MAGIC_PACKET	(0x1 << 0)
 #define MACB_WOL_ENABLED		(0x1 << 1)
@@ -1223,7 +1228,8 @@ static void macb_poll_controller(struct net_device *dev)
 
 static unsigned int macb_tx_map(struct macb *bp,
 				struct macb_queue *queue,
-				struct sk_buff *skb)
+				struct sk_buff *skb,
+				unsigned int hdrlen)
 {
 	dma_addr_t mapping;
 	unsigned int len, entry, i, tx_head = queue->tx_head;
@@ -1231,14 +1237,27 @@ static unsigned int macb_tx_map(struct macb *bp,
 	struct macb_dma_desc *desc;
 	unsigned int offset, size, count = 0;
 	unsigned int f, nr_frags = skb_shinfo(skb)->nr_frags;
-	unsigned int eof = 1;
-	u32 ctrl;
+	unsigned int eof = 1, mss_mfs = 0;
+	u32 ctrl, lso_ctrl = 0, seq_ctrl = 0;
+
+	/* LSO */
+	if (skb_shinfo(skb)->gso_size != 0) {
+		if (ip_hdr(skb)->protocol == IPPROTO_UDP)
+			/* UDP - UFO */
+			lso_ctrl = MACB_LSO_UFO_ENABLE;
+		else
+			/* TCP - TSO */
+			lso_ctrl = MACB_LSO_TSO_ENABLE;
+	}
 
 	/* First, map non-paged data */
 	len = skb_headlen(skb);
+
+	/* first buffer length */
+	size = hdrlen;
+
 	offset = 0;
 	while (len) {
-		size = min(len, bp->max_tx_length);
 		entry = macb_tx_ring_wrap(bp, tx_head);
 		tx_skb = &queue->tx_skb[entry];
 
@@ -1258,6 +1277,8 @@ static unsigned int macb_tx_map(struct macb *bp,
 		offset += size;
 		count++;
 		tx_head++;
+
+		size = min(len, bp->max_tx_length);
 	}
 
 	/* Then, map paged data from fragments */
@@ -1311,6 +1332,21 @@ static unsigned int macb_tx_map(struct macb *bp,
 	desc = &queue->tx_ring[entry];
 	desc->ctrl = ctrl;
 
+	if (lso_ctrl) {
+		if (lso_ctrl == MACB_LSO_UFO_ENABLE)
+			/* include header and FCS in value given to h/w */
+			mss_mfs = skb_shinfo(skb)->gso_size +
+					skb_transport_offset(skb) +
+					ETH_FCS_LEN;
+		else /* TSO */ {
+			mss_mfs = skb_shinfo(skb)->gso_size;
+			/* TCP Sequence Number Source Select
+			 * can be set only for TSO
+			 */
+			seq_ctrl = 0;
+		}
+	}
+
 	do {
 		i--;
 		entry = macb_tx_ring_wrap(bp, i);
@@ -1325,6 +1361,16 @@ static unsigned int macb_tx_map(struct macb *bp,
 		if (unlikely(entry == (bp->tx_ring_size - 1)))
 			ctrl |= MACB_BIT(TX_WRAP);
 
+		/* First descriptor is header descriptor */
+		if (i == queue->tx_head) {
+			ctrl |= MACB_BF(TX_LSO, lso_ctrl);
+			ctrl |= MACB_BF(TX_TCP_SEQ_SRC, seq_ctrl);
+		} else
+			/* Only set MSS/MFS on payload descriptors
+			 * (second or later descriptor)
+			 */
+			ctrl |= MACB_BF(MSS_MFS, mss_mfs);
+
 		/* Set TX buffer descriptor */
 		macb_set_addr(desc, tx_skb->mapping);
 		/* desc->addr must be visible to hardware before clearing
@@ -1350,6 +1396,43 @@ static unsigned int macb_tx_map(struct macb *bp,
 	return 0;
 }
 
+static netdev_features_t macb_features_check(struct sk_buff *skb,
+					     struct net_device *dev,
+					     netdev_features_t features)
+{
+	unsigned int nr_frags, f;
+	unsigned int hdrlen;
+
+	/* Validate LSO compatibility */
+
+	/* there is only one buffer */
+	if (!skb_is_nonlinear(skb))
+		return features;
+
+	/* length of header */
+	hdrlen = skb_transport_offset(skb);
+	if (ip_hdr(skb)->protocol == IPPROTO_TCP)
+		hdrlen += tcp_hdrlen(skb);
+
+	/* For LSO:
+	 * When software supplies two or more payload buffers all payload buffers
+	 * apart from the last must be a multiple of 8 bytes in size.
+	 */
+	if (!IS_ALIGNED(skb_headlen(skb) - hdrlen, MACB_TX_LEN_ALIGN))
+		return features & ~MACB_NETIF_LSO;
+
+	nr_frags = skb_shinfo(skb)->nr_frags;
+	/* No need to check last fragment */
+	nr_frags--;
+	for (f = 0; f < nr_frags; f++) {
+		const skb_frag_t *frag = &skb_shinfo(skb)->frags[f];
+
+		if (!IS_ALIGNED(skb_frag_size(frag), MACB_TX_LEN_ALIGN))
+			return features & ~MACB_NETIF_LSO;
+	}
+	return features;
+}
+
 static inline int macb_clear_csum(struct sk_buff *skb)
 {
 	/* no change for packets without checksum offloading */
@@ -1374,7 +1457,28 @@ static int macb_start_xmit(struct sk_buff *skb, struct net_device *dev)
 	struct macb *bp = netdev_priv(dev);
 	struct macb_queue *queue = &bp->queues[queue_index];
 	unsigned long flags;
-	unsigned int count, nr_frags, frag_size, f;
+	unsigned int desc_cnt, nr_frags, frag_size, f;
+	unsigned int hdrlen;
+	bool is_lso, is_udp = 0;
+
+	is_lso = (skb_shinfo(skb)->gso_size != 0);
+
+	if (is_lso) {
+		is_udp = !!(ip_hdr(skb)->protocol == IPPROTO_UDP);
+
+		/* length of headers */
+		if (is_udp)
+			/* only queue eth + ip headers separately for UDP */
+			hdrlen = skb_transport_offset(skb);
+		else
+			hdrlen = skb_transport_offset(skb) + tcp_hdrlen(skb);
+		if (skb_headlen(skb) < hdrlen) {
+			netdev_err(bp->dev, "Error - LSO headers fragmented!!!\n");
+			/* if this is required, would need to copy to single buffer */
+			return NETDEV_TX_BUSY;
+		}
+	} else
+		hdrlen = min(skb_headlen(skb), bp->max_tx_length);
 
 #if defined(DEBUG) && defined(VERBOSE_DEBUG)
 	netdev_vdbg(bp->dev,
@@ -1389,18 +1493,22 @@ static int macb_start_xmit(struct sk_buff *skb, struct net_device *dev)
 	 * socket buffer: skb fragments of jumbo frames may need to be
 	 * split into many buffer descriptors.
 	 */
-	count = DIV_ROUND_UP(skb_headlen(skb), bp->max_tx_length);
+	if (is_lso && (skb_headlen(skb) > hdrlen))
+		/* extra header descriptor if also payload in first buffer */
+		desc_cnt = DIV_ROUND_UP((skb_headlen(skb) - hdrlen), bp->max_tx_length) + 1;
+	else
+		desc_cnt = DIV_ROUND_UP(skb_headlen(skb), bp->max_tx_length);
 	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 += DIV_ROUND_UP(frag_size, bp->max_tx_length);
+		desc_cnt += DIV_ROUND_UP(frag_size, bp->max_tx_length);
 	}
 
 	spin_lock_irqsave(&bp->lock, flags);
 
 	/* This is a hard error, log it. */
 	if (CIRC_SPACE(queue->tx_head, queue->tx_tail,
-		       bp->tx_ring_size) < count) {
+		       bp->tx_ring_size) < desc_cnt) {
 		netif_stop_subqueue(dev, queue_index);
 		spin_unlock_irqrestore(&bp->lock, flags);
 		netdev_dbg(bp->dev, "tx_head = %u, tx_tail = %u\n",
@@ -1408,13 +1516,17 @@ static int macb_start_xmit(struct sk_buff *skb, struct net_device *dev)
 		return NETDEV_TX_BUSY;
 	}
 
+	if (is_udp) /* is_udp is only set when (is_lso) is checked */
+		/* zero UDP checksum, not calculated by h/w for UFO */
+		udp_hdr(skb)->check = 0;
+
 	if (macb_clear_csum(skb)) {
 		dev_kfree_skb_any(skb);
 		goto unlock;
 	}
 
 	/* Map socket buffer for DMA transfer */
-	if (!macb_tx_map(bp, queue, skb)) {
+	if (!macb_tx_map(bp, queue, skb, hdrlen)) {
 		dev_kfree_skb_any(skb);
 		goto unlock;
 	}
@@ -2354,6 +2466,7 @@ static const struct net_device_ops macb_netdev_ops = {
 	.ndo_poll_controller	= macb_poll_controller,
 #endif
 	.ndo_set_features	= macb_set_features,
+	.ndo_features_check	= macb_features_check,
 };
 
 /* Configure peripheral capabilities according to device tree
@@ -2560,6 +2673,11 @@ static int macb_init(struct platform_device *pdev)
 
 	/* Set features */
 	dev->hw_features = NETIF_F_SG;
+
+	/* Check LSO capability */
+	if (GEM_BFEXT(PBUF_LSO, gem_readl(bp, DCFG6)))
+		dev->hw_features |= MACB_NETIF_LSO;
+
 	/* 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 | NETIF_F_RXCSUM;
diff --git a/drivers/net/ethernet/cadence/macb.h b/drivers/net/ethernet/cadence/macb.h
index 1216950..d67adad 100644
--- a/drivers/net/ethernet/cadence/macb.h
+++ b/drivers/net/ethernet/cadence/macb.h
@@ -382,6 +382,10 @@
 #define GEM_TX_PKT_BUFF_OFFSET			21
 #define GEM_TX_PKT_BUFF_SIZE			1
 
+/* Bitfields in DCFG6. */
+#define GEM_PBUF_LSO_OFFSET			27
+#define GEM_PBUF_LSO_SIZE			1
+
 /* Constants for CLK */
 #define MACB_CLK_DIV8				0
 #define MACB_CLK_DIV16				1
@@ -414,6 +418,10 @@
 #define MACB_CAPS_SG_DISABLED			0x40000000
 #define MACB_CAPS_MACB_IS_GEM			0x80000000
 
+/* LSO settings */
+#define MACB_LSO_UFO_ENABLE			0x01
+#define MACB_LSO_TSO_ENABLE			0x02
+
 /* Bit manipulation macros */
 #define MACB_BIT(name)					\
 	(1 << MACB_##name##_OFFSET)
@@ -545,6 +553,12 @@ struct macb_dma_desc {
 #define MACB_TX_LAST_SIZE			1
 #define MACB_TX_NOCRC_OFFSET			16
 #define MACB_TX_NOCRC_SIZE			1
+#define MACB_MSS_MFS_OFFSET			16
+#define MACB_MSS_MFS_SIZE			14
+#define MACB_TX_LSO_OFFSET			17
+#define MACB_TX_LSO_SIZE			2
+#define MACB_TX_TCP_SEQ_SRC_OFFSET		19
+#define MACB_TX_TCP_SEQ_SRC_SIZE		1
 #define MACB_TX_BUF_EXHAUSTED_OFFSET		27
 #define MACB_TX_BUF_EXHAUSTED_SIZE		1
 #define MACB_TX_UNDERRUN_OFFSET			28
-- 
2.4.5

Re: [PATCH net-next v5]] cadence: Add LSO support.

[David Miller]

From: Rafal Ozieblo <rafalo@cadence.com>
Date: Wed, 9 Nov 2016 13:41:02 +0000

First, please remove the spurious closing bracket in your Subject line
in future submittions.

> +	if (is_udp) /* is_udp is only set when (is_lso) is checked */
> +		/* zero UDP checksum, not calculated by h/w for UFO */
> +		udp_hdr(skb)->check = 0;

This is really not ok.

If UFO is in use it should not silently disable UDP checksums.

If you cannot support UFO with proper checksumming, then you cannot
enable support for that feature.

[PATCH net-next v6] cadence: Add LSO support.

[Rafal Ozieblo]

New Cadence GEM hardware support Large Segment Offload (LSO):
TCP segmentation offload (TSO) as well as UDP fragmentation
offload (UFO). Support for those features was added to the driver.
---
Changed in v2:
macb_lso_check_compatibility() changed to macb_features_check()
(with little modifications) and bind to .ndo_features_check.
(after Eric Dumazet suggestion)
---
Changed in v3:
Respin to net-next.
---
Changed in v4:
(struct iphdr*)skb_network_header(skb) changed to ip_hdr(skb)
---
Changed in v5:
Changes after Florian Fainelli comments
---
Changes in v6:
UDP checksum zeroing removed. There is no need to zeroing
UDP checksum during UFO operation.

Signed-off-by: Rafal Ozieblo <rafalo@cadence.com>
---
 drivers/net/ethernet/cadence/macb.c | 138 ++++++++++++++++++++++++++++++++----
 drivers/net/ethernet/cadence/macb.h |  14 ++++
 2 files changed, 140 insertions(+), 12 deletions(-)

diff --git a/drivers/net/ethernet/cadence/macb.c b/drivers/net/ethernet/cadence/macb.c
index e1847ce..654b5bf 100644
--- a/drivers/net/ethernet/cadence/macb.c
+++ b/drivers/net/ethernet/cadence/macb.c
@@ -32,7 +32,9 @@
 #include <linux/of_gpio.h>
 #include <linux/of_mdio.h>
 #include <linux/of_net.h>
-
+#include <linux/ip.h>
+#include <linux/udp.h>
+#include <linux/tcp.h>
 #include "macb.h"
 
 #define MACB_RX_BUFFER_SIZE	128
@@ -60,10 +62,13 @@
 					| 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))
+/* Max length of transmit frame must be a multiple of 8 bytes */
+#define MACB_TX_LEN_ALIGN	8
+#define MACB_MAX_TX_LEN		((unsigned int)((1 << MACB_TX_FRMLEN_SIZE) - 1) & ~((unsigned int)(MACB_TX_LEN_ALIGN - 1)))
+#define GEM_MAX_TX_LEN		((unsigned int)((1 << GEM_TX_FRMLEN_SIZE) - 1) & ~((unsigned int)(MACB_TX_LEN_ALIGN - 1)))
 
 #define GEM_MTU_MIN_SIZE	ETH_MIN_MTU
+#define MACB_NETIF_LSO		(NETIF_F_TSO | NETIF_F_UFO)
 
 #define MACB_WOL_HAS_MAGIC_PACKET	(0x1 << 0)
 #define MACB_WOL_ENABLED		(0x1 << 1)
@@ -1223,7 +1228,8 @@ static void macb_poll_controller(struct net_device *dev)
 
 static unsigned int macb_tx_map(struct macb *bp,
 				struct macb_queue *queue,
-				struct sk_buff *skb)
+				struct sk_buff *skb,
+				unsigned int hdrlen)
 {
 	dma_addr_t mapping;
 	unsigned int len, entry, i, tx_head = queue->tx_head;
@@ -1231,14 +1237,27 @@ static unsigned int macb_tx_map(struct macb *bp,
 	struct macb_dma_desc *desc;
 	unsigned int offset, size, count = 0;
 	unsigned int f, nr_frags = skb_shinfo(skb)->nr_frags;
-	unsigned int eof = 1;
-	u32 ctrl;
+	unsigned int eof = 1, mss_mfs = 0;
+	u32 ctrl, lso_ctrl = 0, seq_ctrl = 0;
+
+	/* LSO */
+	if (skb_shinfo(skb)->gso_size != 0) {
+		if (ip_hdr(skb)->protocol == IPPROTO_UDP)
+			/* UDP - UFO */
+			lso_ctrl = MACB_LSO_UFO_ENABLE;
+		else
+			/* TCP - TSO */
+			lso_ctrl = MACB_LSO_TSO_ENABLE;
+	}
 
 	/* First, map non-paged data */
 	len = skb_headlen(skb);
+
+	/* first buffer length */
+	size = hdrlen;
+
 	offset = 0;
 	while (len) {
-		size = min(len, bp->max_tx_length);
 		entry = macb_tx_ring_wrap(bp, tx_head);
 		tx_skb = &queue->tx_skb[entry];
 
@@ -1258,6 +1277,8 @@ static unsigned int macb_tx_map(struct macb *bp,
 		offset += size;
 		count++;
 		tx_head++;
+
+		size = min(len, bp->max_tx_length);
 	}
 
 	/* Then, map paged data from fragments */
@@ -1311,6 +1332,21 @@ static unsigned int macb_tx_map(struct macb *bp,
 	desc = &queue->tx_ring[entry];
 	desc->ctrl = ctrl;
 
+	if (lso_ctrl) {
+		if (lso_ctrl == MACB_LSO_UFO_ENABLE)
+			/* include header and FCS in value given to h/w */
+			mss_mfs = skb_shinfo(skb)->gso_size +
+					skb_transport_offset(skb) +
+					ETH_FCS_LEN;
+		else /* TSO */ {
+			mss_mfs = skb_shinfo(skb)->gso_size;
+			/* TCP Sequence Number Source Select
+			 * can be set only for TSO
+			 */
+			seq_ctrl = 0;
+		}
+	}
+
 	do {
 		i--;
 		entry = macb_tx_ring_wrap(bp, i);
@@ -1325,6 +1361,16 @@ static unsigned int macb_tx_map(struct macb *bp,
 		if (unlikely(entry == (bp->tx_ring_size - 1)))
 			ctrl |= MACB_BIT(TX_WRAP);
 
+		/* First descriptor is header descriptor */
+		if (i == queue->tx_head) {
+			ctrl |= MACB_BF(TX_LSO, lso_ctrl);
+			ctrl |= MACB_BF(TX_TCP_SEQ_SRC, seq_ctrl);
+		} else
+			/* Only set MSS/MFS on payload descriptors
+			 * (second or later descriptor)
+			 */
+			ctrl |= MACB_BF(MSS_MFS, mss_mfs);
+
 		/* Set TX buffer descriptor */
 		macb_set_addr(desc, tx_skb->mapping);
 		/* desc->addr must be visible to hardware before clearing
@@ -1350,6 +1396,43 @@ static unsigned int macb_tx_map(struct macb *bp,
 	return 0;
 }
 
+static netdev_features_t macb_features_check(struct sk_buff *skb,
+					     struct net_device *dev,
+					     netdev_features_t features)
+{
+	unsigned int nr_frags, f;
+	unsigned int hdrlen;
+
+	/* Validate LSO compatibility */
+
+	/* there is only one buffer */
+	if (!skb_is_nonlinear(skb))
+		return features;
+
+	/* length of header */
+	hdrlen = skb_transport_offset(skb);
+	if (ip_hdr(skb)->protocol == IPPROTO_TCP)
+		hdrlen += tcp_hdrlen(skb);
+
+	/* For LSO:
+	 * When software supplies two or more payload buffers all payload buffers
+	 * apart from the last must be a multiple of 8 bytes in size.
+	 */
+	if (!IS_ALIGNED(skb_headlen(skb) - hdrlen, MACB_TX_LEN_ALIGN))
+		return features & ~MACB_NETIF_LSO;
+
+	nr_frags = skb_shinfo(skb)->nr_frags;
+	/* No need to check last fragment */
+	nr_frags--;
+	for (f = 0; f < nr_frags; f++) {
+		const skb_frag_t *frag = &skb_shinfo(skb)->frags[f];
+
+		if (!IS_ALIGNED(skb_frag_size(frag), MACB_TX_LEN_ALIGN))
+			return features & ~MACB_NETIF_LSO;
+	}
+	return features;
+}
+
 static inline int macb_clear_csum(struct sk_buff *skb)
 {
 	/* no change for packets without checksum offloading */
@@ -1374,7 +1457,28 @@ static int macb_start_xmit(struct sk_buff *skb, struct net_device *dev)
 	struct macb *bp = netdev_priv(dev);
 	struct macb_queue *queue = &bp->queues[queue_index];
 	unsigned long flags;
-	unsigned int count, nr_frags, frag_size, f;
+	unsigned int desc_cnt, nr_frags, frag_size, f;
+	unsigned int hdrlen;
+	bool is_lso, is_udp = 0;
+
+	is_lso = (skb_shinfo(skb)->gso_size != 0);
+
+	if (is_lso) {
+		is_udp = !!(ip_hdr(skb)->protocol == IPPROTO_UDP);
+
+		/* length of headers */
+		if (is_udp)
+			/* only queue eth + ip headers separately for UDP */
+			hdrlen = skb_transport_offset(skb);
+		else
+			hdrlen = skb_transport_offset(skb) + tcp_hdrlen(skb);
+		if (skb_headlen(skb) < hdrlen) {
+			netdev_err(bp->dev, "Error - LSO headers fragmented!!!\n");
+			/* if this is required, would need to copy to single buffer */
+			return NETDEV_TX_BUSY;
+		}
+	} else
+		hdrlen = min(skb_headlen(skb), bp->max_tx_length);
 
 #if defined(DEBUG) && defined(VERBOSE_DEBUG)
 	netdev_vdbg(bp->dev,
@@ -1389,18 +1493,22 @@ static int macb_start_xmit(struct sk_buff *skb, struct net_device *dev)
 	 * socket buffer: skb fragments of jumbo frames may need to be
 	 * split into many buffer descriptors.
 	 */
-	count = DIV_ROUND_UP(skb_headlen(skb), bp->max_tx_length);
+	if (is_lso && (skb_headlen(skb) > hdrlen))
+		/* extra header descriptor if also payload in first buffer */
+		desc_cnt = DIV_ROUND_UP((skb_headlen(skb) - hdrlen), bp->max_tx_length) + 1;
+	else
+		desc_cnt = DIV_ROUND_UP(skb_headlen(skb), bp->max_tx_length);
 	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 += DIV_ROUND_UP(frag_size, bp->max_tx_length);
+		desc_cnt += DIV_ROUND_UP(frag_size, bp->max_tx_length);
 	}
 
 	spin_lock_irqsave(&bp->lock, flags);
 
 	/* This is a hard error, log it. */
 	if (CIRC_SPACE(queue->tx_head, queue->tx_tail,
-		       bp->tx_ring_size) < count) {
+		       bp->tx_ring_size) < desc_cnt) {
 		netif_stop_subqueue(dev, queue_index);
 		spin_unlock_irqrestore(&bp->lock, flags);
 		netdev_dbg(bp->dev, "tx_head = %u, tx_tail = %u\n",
@@ -1414,7 +1522,7 @@ static int macb_start_xmit(struct sk_buff *skb, struct net_device *dev)
 	}
 
 	/* Map socket buffer for DMA transfer */
-	if (!macb_tx_map(bp, queue, skb)) {
+	if (!macb_tx_map(bp, queue, skb, hdrlen)) {
 		dev_kfree_skb_any(skb);
 		goto unlock;
 	}
@@ -2354,6 +2462,7 @@ static const struct net_device_ops macb_netdev_ops = {
 	.ndo_poll_controller	= macb_poll_controller,
 #endif
 	.ndo_set_features	= macb_set_features,
+	.ndo_features_check	= macb_features_check,
 };
 
 /* Configure peripheral capabilities according to device tree
@@ -2560,6 +2669,11 @@ static int macb_init(struct platform_device *pdev)
 
 	/* Set features */
 	dev->hw_features = NETIF_F_SG;
+
+	/* Check LSO capability */
+	if (GEM_BFEXT(PBUF_LSO, gem_readl(bp, DCFG6)))
+		dev->hw_features |= MACB_NETIF_LSO;
+
 	/* 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 | NETIF_F_RXCSUM;
diff --git a/drivers/net/ethernet/cadence/macb.h b/drivers/net/ethernet/cadence/macb.h
index 1216950..d67adad 100644
--- a/drivers/net/ethernet/cadence/macb.h
+++ b/drivers/net/ethernet/cadence/macb.h
@@ -382,6 +382,10 @@
 #define GEM_TX_PKT_BUFF_OFFSET			21
 #define GEM_TX_PKT_BUFF_SIZE			1
 
+/* Bitfields in DCFG6. */
+#define GEM_PBUF_LSO_OFFSET			27
+#define GEM_PBUF_LSO_SIZE			1
+
 /* Constants for CLK */
 #define MACB_CLK_DIV8				0
 #define MACB_CLK_DIV16				1
@@ -414,6 +418,10 @@
 #define MACB_CAPS_SG_DISABLED			0x40000000
 #define MACB_CAPS_MACB_IS_GEM			0x80000000
 
+/* LSO settings */
+#define MACB_LSO_UFO_ENABLE			0x01
+#define MACB_LSO_TSO_ENABLE			0x02
+
 /* Bit manipulation macros */
 #define MACB_BIT(name)					\
 	(1 << MACB_##name##_OFFSET)
@@ -545,6 +553,12 @@ struct macb_dma_desc {
 #define MACB_TX_LAST_SIZE			1
 #define MACB_TX_NOCRC_OFFSET			16
 #define MACB_TX_NOCRC_SIZE			1
+#define MACB_MSS_MFS_OFFSET			16
+#define MACB_MSS_MFS_SIZE			14
+#define MACB_TX_LSO_OFFSET			17
+#define MACB_TX_LSO_SIZE			2
+#define MACB_TX_TCP_SEQ_SRC_OFFSET		19
+#define MACB_TX_TCP_SEQ_SRC_SIZE		1
 #define MACB_TX_BUF_EXHAUSTED_OFFSET		27
 #define MACB_TX_BUF_EXHAUSTED_SIZE		1
 #define MACB_TX_UNDERRUN_OFFSET			28
-- 
2.4.5

Re: [PATCH net-next v6] cadence: Add LSO support.

[David Miller]

From: Rafal Ozieblo <rafalo@cadence.com>
Date: Wed, 16 Nov 2016 10:02:34 +0000

> New Cadence GEM hardware support Large Segment Offload (LSO):
> TCP segmentation offload (TSO) as well as UDP fragmentation
> offload (UFO). Support for those features was added to the driver.
> ---
> Changed in v2:
> macb_lso_check_compatibility() changed to macb_features_check()
> (with little modifications) and bind to .ndo_features_check.
> (after Eric Dumazet suggestion)
> ---
> Changed in v3:
> Respin to net-next.
> ---
> Changed in v4:
> (struct iphdr*)skb_network_header(skb) changed to ip_hdr(skb)
> ---
> Changed in v5:
> Changes after Florian Fainelli comments
> ---
> Changes in v6:
> UDP checksum zeroing removed. There is no need to zeroing
> UDP checksum during UFO operation.
> 
> Signed-off-by: Rafal Ozieblo <rafalo@cadence.com>

Applied.

But you really, truly, screwed up this commit message.

Everything after "---" will be deleted from the commit message when I
apply your patch with GIT.  Which means your entire changelog plus
your signoff were removed.

Please do this properly in the future.