sfc: Firmware-Assisted TSO version 2
authorBert Kenward <bkenward@solarflare.com>
Thu, 17 Nov 2016 10:51:54 +0000 (10:51 +0000)
committerDavid S. Miller <davem@davemloft.net>
Fri, 18 Nov 2016 16:55:38 +0000 (11:55 -0500)
Add support for FATSOv2 to the driver. FATSOv2 offloads far more of the task
 of TCP segmentation to the firmware, such that we now just pass a single
 super-packet to the NIC. This means TSO has a great deal in common with a
 normal DMA transmit, apart from adding a couple of option descriptors.
 NIC-specific checks have been moved off the fast path and in to
 initialisation where possible.

This also moves FATSOv1/SWTSO to a new file (tx_tso.c).  The end of transmit
 and some error handling is now outside TSO, since it is common with other
 code.

Signed-off-by: Edward Cree <ecree@solarflare.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
drivers/net/ethernet/sfc/Makefile
drivers/net/ethernet/sfc/ef10.c
drivers/net/ethernet/sfc/ethtool.c
drivers/net/ethernet/sfc/falcon.c
drivers/net/ethernet/sfc/farch.c
drivers/net/ethernet/sfc/net_driver.h
drivers/net/ethernet/sfc/nic.h
drivers/net/ethernet/sfc/siena.c
drivers/net/ethernet/sfc/tx.c
drivers/net/ethernet/sfc/tx.h [new file with mode: 0644]
drivers/net/ethernet/sfc/tx_tso.c [new file with mode: 0644]

index ce8470fe79d5524f8ac0b1536f70d04e5ede2007..b3b620f3d91f8bf687fc8ff486170f0135706ce9 100644 (file)
@@ -1,7 +1,7 @@
 sfc-y                  += efx.o nic.o farch.o falcon.o siena.o ef10.o tx.o \
                           rx.o selftest.o ethtool.o qt202x_phy.o mdio_10g.o \
                           tenxpress.o txc43128_phy.o falcon_boards.o \
-                          mcdi.o mcdi_port.o mcdi_mon.o ptp.o
+                          mcdi.o mcdi_port.o mcdi_mon.o ptp.o tx_tso.o
 sfc-$(CONFIG_SFC_MTD)  += mtd.o
 sfc-$(CONFIG_SFC_SRIOV)        += sriov.o siena_sriov.o ef10_sriov.o
 
index e61807e6d47b124886bd71d2357cf9cda1a49225..4b69ed9e63362c624b86fc9717f20358459f54f5 100644 (file)
@@ -2086,6 +2086,78 @@ static inline void efx_ef10_push_tx_desc(struct efx_tx_queue *tx_queue,
                        ER_DZ_TX_DESC_UPD, tx_queue->queue);
 }
 
+/* Add Firmware-Assisted TSO v2 option descriptors to a queue.
+ */
+static int efx_ef10_tx_tso_desc(struct efx_tx_queue *tx_queue,
+                               struct sk_buff *skb,
+                               bool *data_mapped)
+{
+       struct efx_tx_buffer *buffer;
+       struct tcphdr *tcp;
+       struct iphdr *ip;
+
+       u16 ipv4_id;
+       u32 seqnum;
+       u32 mss;
+
+       EFX_BUG_ON_PARANOID(tx_queue->tso_version != 2);
+
+       mss = skb_shinfo(skb)->gso_size;
+
+       if (unlikely(mss < 4)) {
+               WARN_ONCE(1, "MSS of %u is too small for TSO v2\n", mss);
+               return -EINVAL;
+       }
+
+       ip = ip_hdr(skb);
+       if (ip->version == 4) {
+               /* Modify IPv4 header if needed. */
+               ip->tot_len = 0;
+               ip->check = 0;
+               ipv4_id = ip->id;
+       } else {
+               /* Modify IPv6 header if needed. */
+               struct ipv6hdr *ipv6 = ipv6_hdr(skb);
+
+               ipv6->payload_len = 0;
+               ipv4_id = 0;
+       }
+
+       tcp = tcp_hdr(skb);
+       seqnum = ntohl(tcp->seq);
+
+       buffer = efx_tx_queue_get_insert_buffer(tx_queue);
+
+       buffer->flags = EFX_TX_BUF_OPTION;
+       buffer->len = 0;
+       buffer->unmap_len = 0;
+       EFX_POPULATE_QWORD_5(buffer->option,
+                       ESF_DZ_TX_DESC_IS_OPT, 1,
+                       ESF_DZ_TX_OPTION_TYPE, ESE_DZ_TX_OPTION_DESC_TSO,
+                       ESF_DZ_TX_TSO_OPTION_TYPE,
+                       ESE_DZ_TX_TSO_OPTION_DESC_FATSO2A,
+                       ESF_DZ_TX_TSO_IP_ID, ipv4_id,
+                       ESF_DZ_TX_TSO_TCP_SEQNO, seqnum
+                       );
+       ++tx_queue->insert_count;
+
+       buffer = efx_tx_queue_get_insert_buffer(tx_queue);
+
+       buffer->flags = EFX_TX_BUF_OPTION;
+       buffer->len = 0;
+       buffer->unmap_len = 0;
+       EFX_POPULATE_QWORD_4(buffer->option,
+                       ESF_DZ_TX_DESC_IS_OPT, 1,
+                       ESF_DZ_TX_OPTION_TYPE, ESE_DZ_TX_OPTION_DESC_TSO,
+                       ESF_DZ_TX_TSO_OPTION_TYPE,
+                       ESE_DZ_TX_TSO_OPTION_DESC_FATSO2B,
+                       ESF_DZ_TX_TSO_TCP_MSS, mss
+                       );
+       ++tx_queue->insert_count;
+
+       return 0;
+}
+
 static void efx_ef10_tx_init(struct efx_tx_queue *tx_queue)
 {
        MCDI_DECLARE_BUF(inbuf, MC_CMD_INIT_TXQ_IN_LEN(EFX_MAX_DMAQ_SIZE * 8 /
@@ -2095,6 +2167,7 @@ static void efx_ef10_tx_init(struct efx_tx_queue *tx_queue)
        struct efx_channel *channel = tx_queue->channel;
        struct efx_nic *efx = tx_queue->efx;
        struct efx_ef10_nic_data *nic_data = efx->nic_data;
+       bool tso_v2 = false;
        size_t inlen;
        dma_addr_t dma_addr;
        efx_qword_t *txd;
@@ -2102,13 +2175,33 @@ static void efx_ef10_tx_init(struct efx_tx_queue *tx_queue)
        int i;
        BUILD_BUG_ON(MC_CMD_INIT_TXQ_OUT_LEN != 0);
 
+       /* TSOv2 is a limited resource that can only be configured on a limited
+        * number of queues. TSO without checksum offload is not really a thing,
+        * so we only enable it for those queues.
+        *
+        * TODO: handle failure to allocate this in the case where we've used
+        * all the queues.
+        */
+       if (csum_offload && (nic_data->datapath_caps2 &
+                       (1 << MC_CMD_GET_CAPABILITIES_V2_OUT_TX_TSO_V2_LBN))) {
+               tso_v2 = true;
+               netif_dbg(efx, hw, efx->net_dev, "Using TSOv2 for channel %u\n",
+                               channel->channel);
+       }
+
        MCDI_SET_DWORD(inbuf, INIT_TXQ_IN_SIZE, tx_queue->ptr_mask + 1);
        MCDI_SET_DWORD(inbuf, INIT_TXQ_IN_TARGET_EVQ, channel->channel);
        MCDI_SET_DWORD(inbuf, INIT_TXQ_IN_LABEL, tx_queue->queue);
        MCDI_SET_DWORD(inbuf, INIT_TXQ_IN_INSTANCE, tx_queue->queue);
-       MCDI_POPULATE_DWORD_2(inbuf, INIT_TXQ_IN_FLAGS,
+       MCDI_POPULATE_DWORD_3(inbuf, INIT_TXQ_IN_FLAGS,
+                             /* This flag was removed from mcdi_pcol.h for
+                              * the non-_EXT version of INIT_TXQ.  However,
+                              * firmware still honours it.
+                              */
+                             INIT_TXQ_EXT_IN_FLAG_TSOV2_EN, tso_v2,
                              INIT_TXQ_IN_FLAG_IP_CSUM_DIS, !csum_offload,
                              INIT_TXQ_IN_FLAG_TCP_CSUM_DIS, !csum_offload);
+
        MCDI_SET_DWORD(inbuf, INIT_TXQ_IN_OWNER_ID, 0);
        MCDI_SET_DWORD(inbuf, INIT_TXQ_IN_PORT_ID, nic_data->vport_id);
 
@@ -2146,8 +2239,11 @@ static void efx_ef10_tx_init(struct efx_tx_queue *tx_queue)
                             ESF_DZ_TX_OPTION_IP_CSUM, csum_offload);
        tx_queue->write_count = 1;
 
-       if (nic_data->datapath_caps &
-           (1 << MC_CMD_GET_CAPABILITIES_OUT_TX_TSO_LBN)) {
+       if (tso_v2) {
+               tx_queue->handle_tso = efx_ef10_tx_tso_desc;
+               tx_queue->tso_version = 2;
+       } else if (nic_data->datapath_caps &
+                       (1 << MC_CMD_GET_CAPABILITIES_OUT_TX_TSO_LBN)) {
                tx_queue->tso_version = 1;
        }
 
@@ -2202,6 +2298,25 @@ static inline void efx_ef10_notify_tx_desc(struct efx_tx_queue *tx_queue)
                        ER_DZ_TX_DESC_UPD_DWORD, tx_queue->queue);
 }
 
+#define EFX_EF10_MAX_TX_DESCRIPTOR_LEN 0x3fff
+
+static unsigned int efx_ef10_tx_limit_len(struct efx_tx_queue *tx_queue,
+                                         dma_addr_t dma_addr, unsigned int len)
+{
+       if (len > EFX_EF10_MAX_TX_DESCRIPTOR_LEN) {
+               /* If we need to break across multiple descriptors we should
+                * stop at a page boundary. This assumes the length limit is
+                * greater than the page size.
+                */
+               dma_addr_t end = dma_addr + EFX_EF10_MAX_TX_DESCRIPTOR_LEN;
+
+               BUILD_BUG_ON(EFX_EF10_MAX_TX_DESCRIPTOR_LEN < EFX_PAGE_SIZE);
+               len = (end & (~(EFX_PAGE_SIZE - 1))) - dma_addr;
+       }
+
+       return len;
+}
+
 static void efx_ef10_tx_write(struct efx_tx_queue *tx_queue)
 {
        unsigned int old_write_count = tx_queue->write_count;
@@ -5469,6 +5584,7 @@ const struct efx_nic_type efx_hunt_a0_vf_nic_type = {
        .tx_init = efx_ef10_tx_init,
        .tx_remove = efx_ef10_tx_remove,
        .tx_write = efx_ef10_tx_write,
+       .tx_limit_len = efx_ef10_tx_limit_len,
        .rx_push_rss_config = efx_ef10_vf_rx_push_rss_config,
        .rx_probe = efx_ef10_rx_probe,
        .rx_init = efx_ef10_rx_init,
@@ -5575,6 +5691,7 @@ const struct efx_nic_type efx_hunt_a0_nic_type = {
        .tx_init = efx_ef10_tx_init,
        .tx_remove = efx_ef10_tx_remove,
        .tx_write = efx_ef10_tx_write,
+       .tx_limit_len = efx_ef10_tx_limit_len,
        .rx_push_rss_config = efx_ef10_pf_rx_push_rss_config,
        .rx_probe = efx_ef10_rx_probe,
        .rx_init = efx_ef10_rx_init,
index bf126f935ade1b68005bc36112aeab43aff97542..bd5edd61bf64c13670cdf9369f3ea98188cb967a 100644 (file)
@@ -71,6 +71,7 @@ static const struct efx_sw_stat_desc efx_sw_stat_desc[] = {
        EFX_ETHTOOL_UINT_TXQ_STAT(tso_packets),
        EFX_ETHTOOL_UINT_TXQ_STAT(pushes),
        EFX_ETHTOOL_UINT_TXQ_STAT(pio_packets),
+       EFX_ETHTOOL_UINT_TXQ_STAT(cb_packets),
        EFX_ETHTOOL_ATOMIC_NIC_ERROR_STAT(rx_reset),
        EFX_ETHTOOL_UINT_CHANNEL_STAT(rx_tobe_disc),
        EFX_ETHTOOL_UINT_CHANNEL_STAT(rx_ip_hdr_chksum_err),
index 1a7092602aec6b0fad10dc006f504060284a2b52..6a1e74b9344547c3cb32885c3211e744902ef312 100644 (file)
@@ -2750,6 +2750,7 @@ const struct efx_nic_type falcon_a1_nic_type = {
        .tx_init = efx_farch_tx_init,
        .tx_remove = efx_farch_tx_remove,
        .tx_write = efx_farch_tx_write,
+       .tx_limit_len = efx_farch_tx_limit_len,
        .rx_push_rss_config = dummy_rx_push_rss_config,
        .rx_probe = efx_farch_rx_probe,
        .rx_init = efx_farch_rx_init,
@@ -2849,6 +2850,7 @@ const struct efx_nic_type falcon_b0_nic_type = {
        .tx_init = efx_farch_tx_init,
        .tx_remove = efx_farch_tx_remove,
        .tx_write = efx_farch_tx_write,
+       .tx_limit_len = efx_farch_tx_limit_len,
        .rx_push_rss_config = falcon_b0_rx_push_rss_config,
        .rx_probe = efx_farch_rx_probe,
        .rx_init = efx_farch_rx_init,
index 4762ec444cb8ee985cbc09985d07fade1027208b..3d5b91bc4ce67cc226a60c1a98a6c5286e0b759b 100644 (file)
@@ -356,6 +356,21 @@ void efx_farch_tx_write(struct efx_tx_queue *tx_queue)
        }
 }
 
+unsigned int efx_farch_tx_limit_len(struct efx_tx_queue *tx_queue,
+                                   dma_addr_t dma_addr, unsigned int len)
+{
+       /* Don't cross 4K boundaries with descriptors. */
+       unsigned int limit = (~dma_addr & (EFX_PAGE_SIZE - 1)) + 1;
+
+       len = min(limit, len);
+
+       if (EFX_WORKAROUND_5391(tx_queue->efx) && (dma_addr & 0xf))
+               len = min_t(unsigned int, len, 512 - (dma_addr & 0xf));
+
+       return len;
+}
+
+
 /* Allocate hardware resources for a TX queue */
 int efx_farch_tx_probe(struct efx_tx_queue *tx_queue)
 {
index fec51c4b2607457cdc26351b1d68b36020942968..2da3e8fb6d716d35d791caacac8362b722de7d46 100644 (file)
@@ -189,13 +189,17 @@ struct efx_tx_buffer {
  * @channel: The associated channel
  * @core_txq: The networking core TX queue structure
  * @buffer: The software buffer ring
- * @tsoh_page: Array of pages of TSO header buffers
+ * @cb_page: Array of pages of copy buffers.  Carved up according to
+ *     %EFX_TX_CB_ORDER into %EFX_TX_CB_SIZE-sized chunks.
  * @txd: The hardware descriptor ring
  * @ptr_mask: The size of the ring minus 1.
  * @piobuf: PIO buffer region for this TX queue (shared with its partner).
  *     Size of the region is efx_piobuf_size.
  * @piobuf_offset: Buffer offset to be specified in PIO descriptors
  * @initialised: Has hardware queue been initialised?
+ * @tx_min_size: Minimum transmit size for this queue. Depends on HW.
+ * @handle_tso: TSO xmit preparation handler.  Sets up the TSO metadata and
+ *     may also map tx data, depending on the nature of the TSO implementation.
  * @read_count: Current read pointer.
  *     This is the number of buffers that have been removed from both rings.
  * @old_write_count: The value of @write_count when last checked.
@@ -224,6 +228,7 @@ struct efx_tx_buffer {
  * @pushes: Number of times the TX push feature has been used
  * @pio_packets: Number of times the TX PIO feature has been used
  * @xmit_more_available: Are any packets waiting to be pushed to the NIC
+ * @cb_packets: Number of times the TX copybreak feature has been used
  * @empty_read_count: If the completion path has seen the queue as empty
  *     and the transmission path has not yet checked this, the value of
  *     @read_count bitwise-added to %EFX_EMPTY_COUNT_VALID; otherwise 0.
@@ -236,12 +241,16 @@ struct efx_tx_queue {
        struct efx_channel *channel;
        struct netdev_queue *core_txq;
        struct efx_tx_buffer *buffer;
-       struct efx_buffer *tsoh_page;
+       struct efx_buffer *cb_page;
        struct efx_special_buffer txd;
        unsigned int ptr_mask;
        void __iomem *piobuf;
        unsigned int piobuf_offset;
        bool initialised;
+       unsigned int tx_min_size;
+
+       /* Function pointers used in the fast path. */
+       int (*handle_tso)(struct efx_tx_queue*, struct sk_buff*, bool *);
 
        /* Members used mainly on the completion path */
        unsigned int read_count ____cacheline_aligned_in_smp;
@@ -260,6 +269,7 @@ struct efx_tx_queue {
        unsigned int pushes;
        unsigned int pio_packets;
        bool xmit_more_available;
+       unsigned int cb_packets;
        /* Statistics to supplement MAC stats */
        unsigned long tx_packets;
 
@@ -269,6 +279,9 @@ struct efx_tx_queue {
        atomic_t flush_outstanding;
 };
 
+#define EFX_TX_CB_ORDER        7
+#define EFX_TX_CB_SIZE (1 << EFX_TX_CB_ORDER) - NET_IP_ALIGN
+
 /**
  * struct efx_rx_buffer - An Efx RX data buffer
  * @dma_addr: DMA base address of the buffer
@@ -1288,6 +1301,8 @@ struct efx_nic_type {
        void (*tx_init)(struct efx_tx_queue *tx_queue);
        void (*tx_remove)(struct efx_tx_queue *tx_queue);
        void (*tx_write)(struct efx_tx_queue *tx_queue);
+       unsigned int (*tx_limit_len)(struct efx_tx_queue *tx_queue,
+                                    dma_addr_t dma_addr, unsigned int len);
        int (*rx_push_rss_config)(struct efx_nic *efx, bool user,
                                  const u32 *rx_indir_table);
        int (*rx_probe)(struct efx_rx_queue *rx_queue);
@@ -1545,4 +1560,32 @@ static inline netdev_features_t efx_supported_features(const struct efx_nic *efx
        return net_dev->features | net_dev->hw_features;
 }
 
+/* Get the current TX queue insert index. */
+static inline unsigned int
+efx_tx_queue_get_insert_index(const struct efx_tx_queue *tx_queue)
+{
+       return tx_queue->insert_count & tx_queue->ptr_mask;
+}
+
+/* Get a TX buffer. */
+static inline struct efx_tx_buffer *
+__efx_tx_queue_get_insert_buffer(const struct efx_tx_queue *tx_queue)
+{
+       return &tx_queue->buffer[efx_tx_queue_get_insert_index(tx_queue)];
+}
+
+/* Get a TX buffer, checking it's not currently in use. */
+static inline struct efx_tx_buffer *
+efx_tx_queue_get_insert_buffer(const struct efx_tx_queue *tx_queue)
+{
+       struct efx_tx_buffer *buffer =
+               __efx_tx_queue_get_insert_buffer(tx_queue);
+
+       EFX_BUG_ON_PARANOID(buffer->len);
+       EFX_BUG_ON_PARANOID(buffer->flags);
+       EFX_BUG_ON_PARANOID(buffer->unmap_len);
+
+       return buffer;
+}
+
 #endif /* EFX_NET_DRIVER_H */
index 73bee7ea332a9178ae663fa040ec518345af22a6..06dd96e25bb65b2466080c8634f50a99e0e0050b 100644 (file)
@@ -681,6 +681,8 @@ void efx_farch_tx_init(struct efx_tx_queue *tx_queue);
 void efx_farch_tx_fini(struct efx_tx_queue *tx_queue);
 void efx_farch_tx_remove(struct efx_tx_queue *tx_queue);
 void efx_farch_tx_write(struct efx_tx_queue *tx_queue);
+unsigned int efx_farch_tx_limit_len(struct efx_tx_queue *tx_queue,
+                                   dma_addr_t dma_addr, unsigned int len);
 int efx_farch_rx_probe(struct efx_rx_queue *rx_queue);
 void efx_farch_rx_init(struct efx_rx_queue *rx_queue);
 void efx_farch_rx_fini(struct efx_rx_queue *rx_queue);
index 04ed1b4c7cd98ac424d83e54dda2f4f6aee76af7..3975cad19d3771aa0f1b444a6a235a5bf51bef3a 100644 (file)
@@ -977,6 +977,7 @@ const struct efx_nic_type siena_a0_nic_type = {
        .tx_init = efx_farch_tx_init,
        .tx_remove = efx_farch_tx_remove,
        .tx_write = efx_farch_tx_write,
+       .tx_limit_len = efx_farch_tx_limit_len,
        .rx_push_rss_config = siena_rx_push_rss_config,
        .rx_probe = efx_farch_rx_probe,
        .rx_init = efx_farch_rx_init,
index 2337789115579972ae4608445872af0b933b3759..3089e888a08d0da02d1ee94a8c8caeebde384b47 100644 (file)
@@ -22,6 +22,7 @@
 #include "efx.h"
 #include "io.h"
 #include "nic.h"
+#include "tx.h"
 #include "workarounds.h"
 #include "ef10_regs.h"
 
@@ -33,29 +34,30 @@ unsigned int efx_piobuf_size __read_mostly = EFX_PIOBUF_SIZE_DEF;
 
 #endif /* EFX_USE_PIO */
 
-static inline unsigned int
-efx_tx_queue_get_insert_index(const struct efx_tx_queue *tx_queue)
+static inline u8 *efx_tx_get_copy_buffer(struct efx_tx_queue *tx_queue,
+                                        struct efx_tx_buffer *buffer)
 {
-       return tx_queue->insert_count & tx_queue->ptr_mask;
-}
+       unsigned int index = efx_tx_queue_get_insert_index(tx_queue);
+       struct efx_buffer *page_buf =
+               &tx_queue->cb_page[index >> (PAGE_SHIFT - EFX_TX_CB_ORDER)];
+       unsigned int offset =
+               ((index << EFX_TX_CB_ORDER) + NET_IP_ALIGN) & (PAGE_SIZE - 1);
 
-static inline struct efx_tx_buffer *
-__efx_tx_queue_get_insert_buffer(const struct efx_tx_queue *tx_queue)
-{
-       return &tx_queue->buffer[efx_tx_queue_get_insert_index(tx_queue)];
+       if (unlikely(!page_buf->addr) &&
+           efx_nic_alloc_buffer(tx_queue->efx, page_buf, PAGE_SIZE,
+                                GFP_ATOMIC))
+               return NULL;
+       buffer->dma_addr = page_buf->dma_addr + offset;
+       buffer->unmap_len = 0;
+       return (u8 *)page_buf->addr + offset;
 }
 
-static inline struct efx_tx_buffer *
-efx_tx_queue_get_insert_buffer(const struct efx_tx_queue *tx_queue)
+u8 *efx_tx_get_copy_buffer_limited(struct efx_tx_queue *tx_queue,
+                                  struct efx_tx_buffer *buffer, size_t len)
 {
-       struct efx_tx_buffer *buffer =
-               __efx_tx_queue_get_insert_buffer(tx_queue);
-
-       EFX_BUG_ON_PARANOID(buffer->len);
-       EFX_BUG_ON_PARANOID(buffer->flags);
-       EFX_BUG_ON_PARANOID(buffer->unmap_len);
-
-       return buffer;
+       if (len > EFX_TX_CB_SIZE)
+               return NULL;
+       return efx_tx_get_copy_buffer(tx_queue, buffer);
 }
 
 static void efx_dequeue_buffer(struct efx_tx_queue *tx_queue,
@@ -90,27 +92,6 @@ static void efx_dequeue_buffer(struct efx_tx_queue *tx_queue,
        buffer->flags = 0;
 }
 
-static int efx_enqueue_skb_tso(struct efx_tx_queue *tx_queue,
-                              struct sk_buff *skb);
-
-static inline unsigned
-efx_max_tx_len(struct efx_nic *efx, dma_addr_t dma_addr)
-{
-       /* Depending on the NIC revision, we can use descriptor
-        * lengths up to 8K or 8K-1.  However, since PCI Express
-        * devices must split read requests at 4K boundaries, there is
-        * little benefit from using descriptors that cross those
-        * boundaries and we keep things simple by not doing so.
-        */
-       unsigned len = (~dma_addr & (EFX_PAGE_SIZE - 1)) + 1;
-
-       /* Work around hardware bug for unaligned buffers. */
-       if (EFX_WORKAROUND_5391(efx) && (dma_addr & 0xf))
-               len = min_t(unsigned, len, 512 - (dma_addr & 0xf));
-
-       return len;
-}
-
 unsigned int efx_tx_max_skb_descs(struct efx_nic *efx)
 {
        /* Header and payload descriptor for each output segment, plus
@@ -173,6 +154,39 @@ static void efx_tx_maybe_stop_queue(struct efx_tx_queue *txq1)
        }
 }
 
+static int efx_enqueue_skb_copy(struct efx_tx_queue *tx_queue,
+                               struct sk_buff *skb)
+{
+       unsigned int min_len = tx_queue->tx_min_size;
+       unsigned int copy_len = skb->len;
+       struct efx_tx_buffer *buffer;
+       u8 *copy_buffer;
+       int rc;
+
+       EFX_BUG_ON_PARANOID(copy_len > EFX_TX_CB_SIZE);
+
+       buffer = efx_tx_queue_get_insert_buffer(tx_queue);
+
+       copy_buffer = efx_tx_get_copy_buffer(tx_queue, buffer);
+       if (unlikely(!copy_buffer))
+               return -ENOMEM;
+
+       rc = skb_copy_bits(skb, 0, copy_buffer, copy_len);
+       EFX_WARN_ON_PARANOID(rc);
+       if (unlikely(copy_len < min_len)) {
+               memset(copy_buffer + copy_len, 0, min_len - copy_len);
+               buffer->len = min_len;
+       } else {
+               buffer->len = copy_len;
+       }
+
+       buffer->skb = skb;
+       buffer->flags = EFX_TX_BUF_SKB;
+
+       ++tx_queue->insert_count;
+       return rc;
+}
+
 #ifdef EFX_USE_PIO
 
 struct efx_short_copy_buffer {
@@ -267,8 +281,8 @@ static void efx_skb_copy_bits_to_pio(struct efx_nic *efx, struct sk_buff *skb,
        EFX_BUG_ON_PARANOID(skb_shinfo(skb)->frag_list);
 }
 
-static struct efx_tx_buffer *
-efx_enqueue_skb_pio(struct efx_tx_queue *tx_queue, struct sk_buff *skb)
+static int efx_enqueue_skb_pio(struct efx_tx_queue *tx_queue,
+                              struct sk_buff *skb)
 {
        struct efx_tx_buffer *buffer =
                efx_tx_queue_get_insert_buffer(tx_queue);
@@ -292,7 +306,7 @@ efx_enqueue_skb_pio(struct efx_tx_queue *tx_queue, struct sk_buff *skb)
                efx_flush_copy_buffer(tx_queue->efx, piobuf, &copy_buf);
        } else {
                /* Pad the write to the size of a cache line.
-                * We can do this because we know the skb_shared_info sruct is
+                * We can do this because we know the skb_shared_info struct is
                 * after the source, and the destination buffer is big enough.
                 */
                BUILD_BUG_ON(L1_CACHE_BYTES >
@@ -301,6 +315,9 @@ efx_enqueue_skb_pio(struct efx_tx_queue *tx_queue, struct sk_buff *skb)
                                 ALIGN(skb->len, L1_CACHE_BYTES) >> 3);
        }
 
+       buffer->skb = skb;
+       buffer->flags = EFX_TX_BUF_SKB | EFX_TX_BUF_OPTION;
+
        EFX_POPULATE_QWORD_5(buffer->option,
                             ESF_DZ_TX_DESC_IS_OPT, 1,
                             ESF_DZ_TX_OPTION_TYPE, ESE_DZ_TX_OPTION_DESC_PIO,
@@ -308,127 +325,192 @@ efx_enqueue_skb_pio(struct efx_tx_queue *tx_queue, struct sk_buff *skb)
                             ESF_DZ_TX_PIO_BYTE_CNT, skb->len,
                             ESF_DZ_TX_PIO_BUF_ADDR,
                             tx_queue->piobuf_offset);
-       ++tx_queue->pio_packets;
        ++tx_queue->insert_count;
-       return buffer;
+       return 0;
 }
 #endif /* EFX_USE_PIO */
 
-/*
- * Add a socket buffer to a TX queue
- *
- * This maps all fragments of a socket buffer for DMA and adds them to
- * the TX queue.  The queue's insert pointer will be incremented by
- * the number of fragments in the socket buffer.
- *
- * If any DMA mapping fails, any mapped fragments will be unmapped,
- * the queue's insert pointer will be restored to its original value.
- *
- * This function is split out from efx_hard_start_xmit to allow the
- * loopback test to direct packets via specific TX queues.
- *
- * Returns NETDEV_TX_OK.
- * You must hold netif_tx_lock() to call this function.
- */
-netdev_tx_t efx_enqueue_skb(struct efx_tx_queue *tx_queue, struct sk_buff *skb)
+static struct efx_tx_buffer *efx_tx_map_chunk(struct efx_tx_queue *tx_queue,
+                                             dma_addr_t dma_addr,
+                                             size_t len)
 {
-       struct efx_nic *efx = tx_queue->efx;
-       struct device *dma_dev = &efx->pci_dev->dev;
+       const struct efx_nic_type *nic_type = tx_queue->efx->type;
        struct efx_tx_buffer *buffer;
-       unsigned int old_insert_count = tx_queue->insert_count;
-       skb_frag_t *fragment;
-       unsigned int len, unmap_len = 0;
-       dma_addr_t dma_addr, unmap_addr = 0;
        unsigned int dma_len;
-       unsigned short dma_flags;
-       int i = 0;
 
-       if (skb_shinfo(skb)->gso_size)
-               return efx_enqueue_skb_tso(tx_queue, skb);
+       /* Map the fragment taking account of NIC-dependent DMA limits. */
+       do {
+               buffer = efx_tx_queue_get_insert_buffer(tx_queue);
+               dma_len = nic_type->tx_limit_len(tx_queue, dma_addr, len);
 
-       /* Get size of the initial fragment */
-       len = skb_headlen(skb);
+               buffer->len = dma_len;
+               buffer->dma_addr = dma_addr;
+               buffer->flags = EFX_TX_BUF_CONT;
+               len -= dma_len;
+               dma_addr += dma_len;
+               ++tx_queue->insert_count;
+       } while (len);
 
-       /* Pad if necessary */
-       if (EFX_WORKAROUND_15592(efx) && skb->len <= 32) {
-               EFX_BUG_ON_PARANOID(skb->data_len);
-               len = 32 + 1;
-               if (skb_pad(skb, len - skb->len))
-                       return NETDEV_TX_OK;
-       }
+       return buffer;
+}
 
-       /* Consider using PIO for short packets */
-#ifdef EFX_USE_PIO
-       if (skb->len <= efx_piobuf_size && !skb->xmit_more &&
-           efx_nic_may_tx_pio(tx_queue)) {
-               buffer = efx_enqueue_skb_pio(tx_queue, skb);
-               dma_flags = EFX_TX_BUF_OPTION;
-               goto finish_packet;
-       }
-#endif
+/* Map all data from an SKB for DMA and create descriptors on the queue.
+ */
+static int efx_tx_map_data(struct efx_tx_queue *tx_queue, struct sk_buff *skb,
+                          unsigned int segment_count)
+{
+       struct efx_nic *efx = tx_queue->efx;
+       struct device *dma_dev = &efx->pci_dev->dev;
+       unsigned int frag_index, nr_frags;
+       dma_addr_t dma_addr, unmap_addr;
+       unsigned short dma_flags;
+       size_t len, unmap_len;
 
-       /* Map for DMA.  Use dma_map_single rather than dma_map_page
-        * since this is more efficient on machines with sparse
-        * memory.
-        */
-       dma_flags = EFX_TX_BUF_MAP_SINGLE;
-       dma_addr = dma_map_single(dma_dev, skb->data, len, PCI_DMA_TODEVICE);
+       nr_frags = skb_shinfo(skb)->nr_frags;
+       frag_index = 0;
 
-       /* Process all fragments */
-       while (1) {
-               if (unlikely(dma_mapping_error(dma_dev, dma_addr)))
-                       goto dma_err;
+       /* Map header data. */
+       len = skb_headlen(skb);
+       dma_addr = dma_map_single(dma_dev, skb->data, len, DMA_TO_DEVICE);
+       dma_flags = EFX_TX_BUF_MAP_SINGLE;
+       unmap_len = len;
+       unmap_addr = dma_addr;
 
-               /* Store fields for marking in the per-fragment final
-                * descriptor */
-               unmap_len = len;
-               unmap_addr = dma_addr;
+       if (unlikely(dma_mapping_error(dma_dev, dma_addr)))
+               return -EIO;
 
-               /* Add to TX queue, splitting across DMA boundaries */
-               do {
-                       buffer = efx_tx_queue_get_insert_buffer(tx_queue);
+       if (segment_count) {
+               /* For TSO we need to put the header in to a separate
+                * descriptor. Map this separately if necessary.
+                */
+               size_t header_len = skb_transport_header(skb) - skb->data +
+                               (tcp_hdr(skb)->doff << 2u);
+
+               if (header_len != len) {
+                       tx_queue->tso_long_headers++;
+                       efx_tx_map_chunk(tx_queue, dma_addr, header_len);
+                       len -= header_len;
+                       dma_addr += header_len;
+               }
+       }
 
-                       dma_len = efx_max_tx_len(efx, dma_addr);
-                       if (likely(dma_len >= len))
-                               dma_len = len;
+       /* Add descriptors for each fragment. */
+       do {
+               struct efx_tx_buffer *buffer;
+               skb_frag_t *fragment;
 
-                       /* Fill out per descriptor fields */
-                       buffer->len = dma_len;
-                       buffer->dma_addr = dma_addr;
-                       buffer->flags = EFX_TX_BUF_CONT;
-                       len -= dma_len;
-                       dma_addr += dma_len;
-                       ++tx_queue->insert_count;
-               } while (len);
+               buffer = efx_tx_map_chunk(tx_queue, dma_addr, len);
 
-               /* Transfer ownership of the unmapping to the final buffer */
+               /* The final descriptor for a fragment is responsible for
+                * unmapping the whole fragment.
+                */
                buffer->flags = EFX_TX_BUF_CONT | dma_flags;
                buffer->unmap_len = unmap_len;
                buffer->dma_offset = buffer->dma_addr - unmap_addr;
-               unmap_len = 0;
 
-               /* Get address and size of next fragment */
-               if (i >= skb_shinfo(skb)->nr_frags)
-                       break;
-               fragment = &skb_shinfo(skb)->frags[i];
+               if (frag_index >= nr_frags) {
+                       /* Store SKB details with the final buffer for
+                        * the completion.
+                        */
+                       buffer->skb = skb;
+                       buffer->flags = EFX_TX_BUF_SKB | dma_flags;
+                       return 0;
+               }
+
+               /* Move on to the next fragment. */
+               fragment = &skb_shinfo(skb)->frags[frag_index++];
                len = skb_frag_size(fragment);
-               i++;
-               /* Map for DMA */
+               dma_addr = skb_frag_dma_map(dma_dev, fragment,
+                               0, len, DMA_TO_DEVICE);
                dma_flags = 0;
-               dma_addr = skb_frag_dma_map(dma_dev, fragment, 0, len,
-                                           DMA_TO_DEVICE);
+               unmap_len = len;
+               unmap_addr = dma_addr;
+
+               if (unlikely(dma_mapping_error(dma_dev, dma_addr)))
+                       return -EIO;
+       } while (1);
+}
+
+/* Remove buffers put into a tx_queue.  None of the buffers must have
+ * an skb attached.
+ */
+static void efx_enqueue_unwind(struct efx_tx_queue *tx_queue)
+{
+       struct efx_tx_buffer *buffer;
+
+       /* Work backwards until we hit the original insert pointer value */
+       while (tx_queue->insert_count != tx_queue->write_count) {
+               --tx_queue->insert_count;
+               buffer = __efx_tx_queue_get_insert_buffer(tx_queue);
+               efx_dequeue_buffer(tx_queue, buffer, NULL, NULL);
        }
+}
+
+static int efx_tx_tso_sw(struct efx_tx_queue *tx_queue, struct sk_buff *skb,
+                        bool *data_mapped)
+{
+       return efx_enqueue_skb_tso(tx_queue, skb, data_mapped);
+}
+
+/*
+ * Add a socket buffer to a TX queue
+ *
+ * This maps all fragments of a socket buffer for DMA and adds them to
+ * the TX queue.  The queue's insert pointer will be incremented by
+ * the number of fragments in the socket buffer.
+ *
+ * If any DMA mapping fails, any mapped fragments will be unmapped,
+ * the queue's insert pointer will be restored to its original value.
+ *
+ * This function is split out from efx_hard_start_xmit to allow the
+ * loopback test to direct packets via specific TX queues.
+ *
+ * Returns NETDEV_TX_OK.
+ * You must hold netif_tx_lock() to call this function.
+ */
+netdev_tx_t efx_enqueue_skb(struct efx_tx_queue *tx_queue, struct sk_buff *skb)
+{
+       bool data_mapped = false;
+       unsigned int segments;
+       unsigned int skb_len;
 
-       /* Transfer ownership of the skb to the final buffer */
+       skb_len = skb->len;
+       segments = skb_is_gso(skb) ? skb_shinfo(skb)->gso_segs : 0;
+       if (segments == 1)
+               segments = 0; /* Don't use TSO for a single segment. */
+
+       /* Handle TSO first - it's *possible* (although unlikely) that we might
+        * be passed a packet to segment that's smaller than the copybreak/PIO
+        * size limit.
+        */
+       if (segments) {
+               EFX_BUG_ON_PARANOID(!tx_queue->handle_tso);
+               if (tx_queue->handle_tso(tx_queue, skb, &data_mapped))
+                       goto err;
 #ifdef EFX_USE_PIO
-finish_packet:
+       } else if (skb_len <= efx_piobuf_size && !skb->xmit_more &&
+                  efx_nic_may_tx_pio(tx_queue)) {
+               /* Use PIO for short packets with an empty queue. */
+               if (efx_enqueue_skb_pio(tx_queue, skb))
+                       goto err;
+               tx_queue->pio_packets++;
+               data_mapped = true;
 #endif
-       buffer->skb = skb;
-       buffer->flags = EFX_TX_BUF_SKB | dma_flags;
+       } else if (skb_len < tx_queue->tx_min_size ||
+                       (skb->data_len && skb_len <= EFX_TX_CB_SIZE)) {
+               /* Pad short packets or coalesce short fragmented packets. */
+               if (efx_enqueue_skb_copy(tx_queue, skb))
+                       goto err;
+               tx_queue->cb_packets++;
+               data_mapped = true;
+       }
 
-       netdev_tx_sent_queue(tx_queue->core_txq, skb->len);
+       /* Map for DMA and create descriptors if we haven't done so already. */
+       if (!data_mapped && (efx_tx_map_data(tx_queue, skb, segments)))
+               goto err;
 
-       efx_tx_maybe_stop_queue(tx_queue);
+       /* Update BQL */
+       netdev_tx_sent_queue(tx_queue->core_txq, skb_len);
 
        /* Pass off to hardware */
        if (!skb->xmit_more || netif_xmit_stopped(tx_queue->core_txq)) {
@@ -446,37 +528,22 @@ finish_packet:
                tx_queue->xmit_more_available = skb->xmit_more;
        }
 
-       tx_queue->tx_packets++;
+       if (segments) {
+               tx_queue->tso_bursts++;
+               tx_queue->tso_packets += segments;
+               tx_queue->tx_packets  += segments;
+       } else {
+               tx_queue->tx_packets++;
+       }
+
+       efx_tx_maybe_stop_queue(tx_queue);
 
        return NETDEV_TX_OK;
 
- dma_err:
-       netif_err(efx, tx_err, efx->net_dev,
-                 " TX queue %d could not map skb with %d bytes %d "
-                 "fragments for DMA\n", tx_queue->queue, skb->len,
-                 skb_shinfo(skb)->nr_frags + 1);
 
-       /* Mark the packet as transmitted, and free the SKB ourselves */
+err:
+       efx_enqueue_unwind(tx_queue);
        dev_kfree_skb_any(skb);
-
-       /* Work backwards until we hit the original insert pointer value */
-       while (tx_queue->insert_count != old_insert_count) {
-               unsigned int pkts_compl = 0, bytes_compl = 0;
-               --tx_queue->insert_count;
-               buffer = __efx_tx_queue_get_insert_buffer(tx_queue);
-               efx_dequeue_buffer(tx_queue, buffer, &pkts_compl, &bytes_compl);
-       }
-
-       /* Free the fragment we were mid-way through pushing */
-       if (unmap_len) {
-               if (dma_flags & EFX_TX_BUF_MAP_SINGLE)
-                       dma_unmap_single(dma_dev, unmap_addr, unmap_len,
-                                        DMA_TO_DEVICE);
-               else
-                       dma_unmap_page(dma_dev, unmap_addr, unmap_len,
-                                      DMA_TO_DEVICE);
-       }
-
        return NETDEV_TX_OK;
 }
 
@@ -667,19 +734,9 @@ void efx_xmit_done(struct efx_tx_queue *tx_queue, unsigned int index)
        }
 }
 
-/* Size of page-based TSO header buffers.  Larger blocks must be
- * allocated from the heap.
- */
-#define TSOH_STD_SIZE  128
-#define TSOH_PER_PAGE  (PAGE_SIZE / TSOH_STD_SIZE)
-
-/* At most half the descriptors in the queue at any time will refer to
- * a TSO header buffer, since they must always be followed by a
- * payload descriptor referring to an skb.
- */
-static unsigned int efx_tsoh_page_count(struct efx_tx_queue *tx_queue)
+static unsigned int efx_tx_cb_page_count(struct efx_tx_queue *tx_queue)
 {
-       return DIV_ROUND_UP(tx_queue->ptr_mask + 1, 2 * TSOH_PER_PAGE);
+       return DIV_ROUND_UP(tx_queue->ptr_mask + 1, PAGE_SIZE >> EFX_TX_CB_ORDER);
 }
 
 int efx_probe_tx_queue(struct efx_tx_queue *tx_queue)
@@ -703,14 +760,11 @@ int efx_probe_tx_queue(struct efx_tx_queue *tx_queue)
        if (!tx_queue->buffer)
                return -ENOMEM;
 
-       if (tx_queue->queue & EFX_TXQ_TYPE_OFFLOAD) {
-               tx_queue->tsoh_page =
-                       kcalloc(efx_tsoh_page_count(tx_queue),
-                               sizeof(tx_queue->tsoh_page[0]), GFP_KERNEL);
-               if (!tx_queue->tsoh_page) {
-                       rc = -ENOMEM;
-                       goto fail1;
-               }
+       tx_queue->cb_page = kcalloc(efx_tx_cb_page_count(tx_queue),
+                                   sizeof(tx_queue->cb_page[0]), GFP_KERNEL);
+       if (!tx_queue->cb_page) {
+               rc = -ENOMEM;
+               goto fail1;
        }
 
        /* Allocate hardware ring */
@@ -721,8 +775,8 @@ int efx_probe_tx_queue(struct efx_tx_queue *tx_queue)
        return 0;
 
 fail2:
-       kfree(tx_queue->tsoh_page);
-       tx_queue->tsoh_page = NULL;
+       kfree(tx_queue->cb_page);
+       tx_queue->cb_page = NULL;
 fail1:
        kfree(tx_queue->buffer);
        tx_queue->buffer = NULL;
@@ -731,7 +785,9 @@ fail1:
 
 void efx_init_tx_queue(struct efx_tx_queue *tx_queue)
 {
-       netif_dbg(tx_queue->efx, drv, tx_queue->efx->net_dev,
+       struct efx_nic *efx = tx_queue->efx;
+
+       netif_dbg(efx, drv, efx->net_dev,
                  "initialising TX queue %d\n", tx_queue->queue);
 
        tx_queue->insert_count = 0;
@@ -742,6 +798,14 @@ void efx_init_tx_queue(struct efx_tx_queue *tx_queue)
        tx_queue->empty_read_count = 0 | EFX_EMPTY_COUNT_VALID;
        tx_queue->xmit_more_available = false;
 
+       /* Set up default function pointers. These may get replaced by
+        * efx_nic_init_tx() based off NIC/queue capabilities.
+        */
+       tx_queue->handle_tso = efx_tx_tso_sw;
+
+       /* Some older hardware requires Tx writes larger than 32. */
+       tx_queue->tx_min_size = EFX_WORKAROUND_15592(efx) ? 33 : 0;
+
        /* Set up TX descriptor ring */
        efx_nic_init_tx(tx_queue);
 
@@ -781,589 +845,14 @@ void efx_remove_tx_queue(struct efx_tx_queue *tx_queue)
                  "destroying TX queue %d\n", tx_queue->queue);
        efx_nic_remove_tx(tx_queue);
 
-       if (tx_queue->tsoh_page) {
-               for (i = 0; i < efx_tsoh_page_count(tx_queue); i++)
+       if (tx_queue->cb_page) {
+               for (i = 0; i < efx_tx_cb_page_count(tx_queue); i++)
                        efx_nic_free_buffer(tx_queue->efx,
-                                           &tx_queue->tsoh_page[i]);
-               kfree(tx_queue->tsoh_page);
-               tx_queue->tsoh_page = NULL;
+                                           &tx_queue->cb_page[i]);
+               kfree(tx_queue->cb_page);
+               tx_queue->cb_page = NULL;
        }
 
        kfree(tx_queue->buffer);
        tx_queue->buffer = NULL;
 }
-
-
-/* Efx TCP segmentation acceleration.
- *
- * Why?  Because by doing it here in the driver we can go significantly
- * faster than the GSO.
- *
- * Requires TX checksum offload support.
- */
-
-#define PTR_DIFF(p1, p2)  ((u8 *)(p1) - (u8 *)(p2))
-
-/**
- * struct tso_state - TSO state for an SKB
- * @out_len: Remaining length in current segment
- * @seqnum: Current sequence number
- * @ipv4_id: Current IPv4 ID, host endian
- * @packet_space: Remaining space in current packet
- * @dma_addr: DMA address of current position
- * @in_len: Remaining length in current SKB fragment
- * @unmap_len: Length of SKB fragment
- * @unmap_addr: DMA address of SKB fragment
- * @dma_flags: TX buffer flags for DMA mapping - %EFX_TX_BUF_MAP_SINGLE or 0
- * @protocol: Network protocol (after any VLAN header)
- * @ip_off: Offset of IP header
- * @tcp_off: Offset of TCP header
- * @header_len: Number of bytes of header
- * @ip_base_len: IPv4 tot_len or IPv6 payload_len, before TCP payload
- * @header_dma_addr: Header DMA address, when using option descriptors
- * @header_unmap_len: Header DMA mapped length, or 0 if not using option
- *     descriptors
- *
- * The state used during segmentation.  It is put into this data structure
- * just to make it easy to pass into inline functions.
- */
-struct tso_state {
-       /* Output position */
-       unsigned out_len;
-       unsigned seqnum;
-       u16 ipv4_id;
-       unsigned packet_space;
-
-       /* Input position */
-       dma_addr_t dma_addr;
-       unsigned in_len;
-       unsigned unmap_len;
-       dma_addr_t unmap_addr;
-       unsigned short dma_flags;
-
-       __be16 protocol;
-       unsigned int ip_off;
-       unsigned int tcp_off;
-       unsigned header_len;
-       unsigned int ip_base_len;
-       dma_addr_t header_dma_addr;
-       unsigned int header_unmap_len;
-};
-
-
-/*
- * Verify that our various assumptions about sk_buffs and the conditions
- * under which TSO will be attempted hold true.  Return the protocol number.
- */
-static __be16 efx_tso_check_protocol(struct sk_buff *skb)
-{
-       __be16 protocol = skb->protocol;
-
-       EFX_BUG_ON_PARANOID(((struct ethhdr *)skb->data)->h_proto !=
-                           protocol);
-       if (protocol == htons(ETH_P_8021Q)) {
-               struct vlan_ethhdr *veh = (struct vlan_ethhdr *)skb->data;
-               protocol = veh->h_vlan_encapsulated_proto;
-       }
-
-       if (protocol == htons(ETH_P_IP)) {
-               EFX_BUG_ON_PARANOID(ip_hdr(skb)->protocol != IPPROTO_TCP);
-       } else {
-               EFX_BUG_ON_PARANOID(protocol != htons(ETH_P_IPV6));
-               EFX_BUG_ON_PARANOID(ipv6_hdr(skb)->nexthdr != NEXTHDR_TCP);
-       }
-       EFX_BUG_ON_PARANOID((PTR_DIFF(tcp_hdr(skb), skb->data)
-                            + (tcp_hdr(skb)->doff << 2u)) >
-                           skb_headlen(skb));
-
-       return protocol;
-}
-
-static u8 *efx_tsoh_get_buffer(struct efx_tx_queue *tx_queue,
-                              struct efx_tx_buffer *buffer, unsigned int len)
-{
-       u8 *result;
-
-       EFX_BUG_ON_PARANOID(buffer->len);
-       EFX_BUG_ON_PARANOID(buffer->flags);
-       EFX_BUG_ON_PARANOID(buffer->unmap_len);
-
-       if (likely(len <= TSOH_STD_SIZE - NET_IP_ALIGN)) {
-               unsigned index =
-                       (tx_queue->insert_count & tx_queue->ptr_mask) / 2;
-               struct efx_buffer *page_buf =
-                       &tx_queue->tsoh_page[index / TSOH_PER_PAGE];
-               unsigned offset =
-                       TSOH_STD_SIZE * (index % TSOH_PER_PAGE) + NET_IP_ALIGN;
-
-               if (unlikely(!page_buf->addr) &&
-                   efx_nic_alloc_buffer(tx_queue->efx, page_buf, PAGE_SIZE,
-                                        GFP_ATOMIC))
-                       return NULL;
-
-               result = (u8 *)page_buf->addr + offset;
-               buffer->dma_addr = page_buf->dma_addr + offset;
-               buffer->flags = EFX_TX_BUF_CONT;
-       } else {
-               tx_queue->tso_long_headers++;
-
-               buffer->heap_buf = kmalloc(NET_IP_ALIGN + len, GFP_ATOMIC);
-               if (unlikely(!buffer->heap_buf))
-                       return NULL;
-               result = (u8 *)buffer->heap_buf + NET_IP_ALIGN;
-               buffer->flags = EFX_TX_BUF_CONT | EFX_TX_BUF_HEAP;
-       }
-
-       buffer->len = len;
-
-       return result;
-}
-
-/**
- * efx_tx_queue_insert - push descriptors onto the TX queue
- * @tx_queue:          Efx TX queue
- * @dma_addr:          DMA address of fragment
- * @len:               Length of fragment
- * @final_buffer:      The final buffer inserted into the queue
- *
- * Push descriptors onto the TX queue.
- */
-static void efx_tx_queue_insert(struct efx_tx_queue *tx_queue,
-                               dma_addr_t dma_addr, unsigned len,
-                               struct efx_tx_buffer **final_buffer)
-{
-       struct efx_tx_buffer *buffer;
-       struct efx_nic *efx = tx_queue->efx;
-       unsigned dma_len;
-
-       EFX_BUG_ON_PARANOID(len <= 0);
-
-       while (1) {
-               buffer = efx_tx_queue_get_insert_buffer(tx_queue);
-               ++tx_queue->insert_count;
-
-               EFX_BUG_ON_PARANOID(tx_queue->insert_count -
-                                   tx_queue->read_count >=
-                                   efx->txq_entries);
-
-               buffer->dma_addr = dma_addr;
-
-               dma_len = efx_max_tx_len(efx, dma_addr);
-
-               /* If there is enough space to send then do so */
-               if (dma_len >= len)
-                       break;
-
-               buffer->len = dma_len;
-               buffer->flags = EFX_TX_BUF_CONT;
-               dma_addr += dma_len;
-               len -= dma_len;
-       }
-
-       EFX_BUG_ON_PARANOID(!len);
-       buffer->len = len;
-       *final_buffer = buffer;
-}
-
-
-/*
- * Put a TSO header into the TX queue.
- *
- * This is special-cased because we know that it is small enough to fit in
- * a single fragment, and we know it doesn't cross a page boundary.  It
- * also allows us to not worry about end-of-packet etc.
- */
-static int efx_tso_put_header(struct efx_tx_queue *tx_queue,
-                             struct efx_tx_buffer *buffer, u8 *header)
-{
-       if (unlikely(buffer->flags & EFX_TX_BUF_HEAP)) {
-               buffer->dma_addr = dma_map_single(&tx_queue->efx->pci_dev->dev,
-                                                 header, buffer->len,
-                                                 DMA_TO_DEVICE);
-               if (unlikely(dma_mapping_error(&tx_queue->efx->pci_dev->dev,
-                                              buffer->dma_addr))) {
-                       kfree(buffer->heap_buf);
-                       buffer->len = 0;
-                       buffer->flags = 0;
-                       return -ENOMEM;
-               }
-               buffer->unmap_len = buffer->len;
-               buffer->dma_offset = 0;
-               buffer->flags |= EFX_TX_BUF_MAP_SINGLE;
-       }
-
-       ++tx_queue->insert_count;
-       return 0;
-}
-
-
-/* Remove buffers put into a tx_queue.  None of the buffers must have
- * an skb attached.
- */
-static void efx_enqueue_unwind(struct efx_tx_queue *tx_queue,
-                              unsigned int insert_count)
-{
-       struct efx_tx_buffer *buffer;
-
-       /* Work backwards until we hit the original insert pointer value */
-       while (tx_queue->insert_count != insert_count) {
-               --tx_queue->insert_count;
-               buffer = __efx_tx_queue_get_insert_buffer(tx_queue);
-               efx_dequeue_buffer(tx_queue, buffer, NULL, NULL);
-       }
-}
-
-
-/* Parse the SKB header and initialise state. */
-static int tso_start(struct tso_state *st, struct efx_nic *efx,
-                    struct efx_tx_queue *tx_queue,
-                    const struct sk_buff *skb)
-{
-       struct device *dma_dev = &efx->pci_dev->dev;
-       unsigned int header_len, in_len;
-       bool use_opt_desc = false;
-       dma_addr_t dma_addr;
-
-       if (tx_queue->tso_version == 1)
-               use_opt_desc = true;
-
-       st->ip_off = skb_network_header(skb) - skb->data;
-       st->tcp_off = skb_transport_header(skb) - skb->data;
-       header_len = st->tcp_off + (tcp_hdr(skb)->doff << 2u);
-       in_len = skb_headlen(skb) - header_len;
-       st->header_len = header_len;
-       st->in_len = in_len;
-       if (st->protocol == htons(ETH_P_IP)) {
-               st->ip_base_len = st->header_len - st->ip_off;
-               st->ipv4_id = ntohs(ip_hdr(skb)->id);
-       } else {
-               st->ip_base_len = st->header_len - st->tcp_off;
-               st->ipv4_id = 0;
-       }
-       st->seqnum = ntohl(tcp_hdr(skb)->seq);
-
-       EFX_BUG_ON_PARANOID(tcp_hdr(skb)->urg);
-       EFX_BUG_ON_PARANOID(tcp_hdr(skb)->syn);
-       EFX_BUG_ON_PARANOID(tcp_hdr(skb)->rst);
-
-       st->out_len = skb->len - header_len;
-
-       if (!use_opt_desc) {
-               st->header_unmap_len = 0;
-
-               if (likely(in_len == 0)) {
-                       st->dma_flags = 0;
-                       st->unmap_len = 0;
-                       return 0;
-               }
-
-               dma_addr = dma_map_single(dma_dev, skb->data + header_len,
-                                         in_len, DMA_TO_DEVICE);
-               st->dma_flags = EFX_TX_BUF_MAP_SINGLE;
-               st->dma_addr = dma_addr;
-               st->unmap_addr = dma_addr;
-               st->unmap_len = in_len;
-       } else {
-               dma_addr = dma_map_single(dma_dev, skb->data,
-                                         skb_headlen(skb), DMA_TO_DEVICE);
-               st->header_dma_addr = dma_addr;
-               st->header_unmap_len = skb_headlen(skb);
-               st->dma_flags = 0;
-               st->dma_addr = dma_addr + header_len;
-               st->unmap_len = 0;
-       }
-
-       return unlikely(dma_mapping_error(dma_dev, dma_addr)) ? -ENOMEM : 0;
-}
-
-static int tso_get_fragment(struct tso_state *st, struct efx_nic *efx,
-                           skb_frag_t *frag)
-{
-       st->unmap_addr = skb_frag_dma_map(&efx->pci_dev->dev, frag, 0,
-                                         skb_frag_size(frag), DMA_TO_DEVICE);
-       if (likely(!dma_mapping_error(&efx->pci_dev->dev, st->unmap_addr))) {
-               st->dma_flags = 0;
-               st->unmap_len = skb_frag_size(frag);
-               st->in_len = skb_frag_size(frag);
-               st->dma_addr = st->unmap_addr;
-               return 0;
-       }
-       return -ENOMEM;
-}
-
-
-/**
- * tso_fill_packet_with_fragment - form descriptors for the current fragment
- * @tx_queue:          Efx TX queue
- * @skb:               Socket buffer
- * @st:                        TSO state
- *
- * Form descriptors for the current fragment, until we reach the end
- * of fragment or end-of-packet.
- */
-static void tso_fill_packet_with_fragment(struct efx_tx_queue *tx_queue,
-                                         const struct sk_buff *skb,
-                                         struct tso_state *st)
-{
-       struct efx_tx_buffer *buffer;
-       int n;
-
-       if (st->in_len == 0)
-               return;
-       if (st->packet_space == 0)
-               return;
-
-       EFX_BUG_ON_PARANOID(st->in_len <= 0);
-       EFX_BUG_ON_PARANOID(st->packet_space <= 0);
-
-       n = min(st->in_len, st->packet_space);
-
-       st->packet_space -= n;
-       st->out_len -= n;
-       st->in_len -= n;
-
-       efx_tx_queue_insert(tx_queue, st->dma_addr, n, &buffer);
-
-       if (st->out_len == 0) {
-               /* Transfer ownership of the skb */
-               buffer->skb = skb;
-               buffer->flags = EFX_TX_BUF_SKB;
-       } else if (st->packet_space != 0) {
-               buffer->flags = EFX_TX_BUF_CONT;
-       }
-
-       if (st->in_len == 0) {
-               /* Transfer ownership of the DMA mapping */
-               buffer->unmap_len = st->unmap_len;
-               buffer->dma_offset = buffer->unmap_len - buffer->len;
-               buffer->flags |= st->dma_flags;
-               st->unmap_len = 0;
-       }
-
-       st->dma_addr += n;
-}
-
-
-/**
- * tso_start_new_packet - generate a new header and prepare for the new packet
- * @tx_queue:          Efx TX queue
- * @skb:               Socket buffer
- * @st:                        TSO state
- *
- * Generate a new header and prepare for the new packet.  Return 0 on
- * success, or -%ENOMEM if failed to alloc header.
- */
-static int tso_start_new_packet(struct efx_tx_queue *tx_queue,
-                               const struct sk_buff *skb,
-                               struct tso_state *st)
-{
-       struct efx_tx_buffer *buffer =
-               efx_tx_queue_get_insert_buffer(tx_queue);
-       bool is_last = st->out_len <= skb_shinfo(skb)->gso_size;
-       u8 tcp_flags_clear;
-
-       if (!is_last) {
-               st->packet_space = skb_shinfo(skb)->gso_size;
-               tcp_flags_clear = 0x09; /* mask out FIN and PSH */
-       } else {
-               st->packet_space = st->out_len;
-               tcp_flags_clear = 0x00;
-       }
-
-       if (!st->header_unmap_len) {
-               /* Allocate and insert a DMA-mapped header buffer. */
-               struct tcphdr *tsoh_th;
-               unsigned ip_length;
-               u8 *header;
-               int rc;
-
-               header = efx_tsoh_get_buffer(tx_queue, buffer, st->header_len);
-               if (!header)
-                       return -ENOMEM;
-
-               tsoh_th = (struct tcphdr *)(header + st->tcp_off);
-
-               /* Copy and update the headers. */
-               memcpy(header, skb->data, st->header_len);
-
-               tsoh_th->seq = htonl(st->seqnum);
-               ((u8 *)tsoh_th)[13] &= ~tcp_flags_clear;
-
-               ip_length = st->ip_base_len + st->packet_space;
-
-               if (st->protocol == htons(ETH_P_IP)) {
-                       struct iphdr *tsoh_iph =
-                               (struct iphdr *)(header + st->ip_off);
-
-                       tsoh_iph->tot_len = htons(ip_length);
-                       tsoh_iph->id = htons(st->ipv4_id);
-               } else {
-                       struct ipv6hdr *tsoh_iph =
-                               (struct ipv6hdr *)(header + st->ip_off);
-
-                       tsoh_iph->payload_len = htons(ip_length);
-               }
-
-               rc = efx_tso_put_header(tx_queue, buffer, header);
-               if (unlikely(rc))
-                       return rc;
-       } else {
-               /* Send the original headers with a TSO option descriptor
-                * in front
-                */
-               u8 tcp_flags = ((u8 *)tcp_hdr(skb))[13] & ~tcp_flags_clear;
-
-               buffer->flags = EFX_TX_BUF_OPTION;
-               buffer->len = 0;
-               buffer->unmap_len = 0;
-               EFX_POPULATE_QWORD_5(buffer->option,
-                                    ESF_DZ_TX_DESC_IS_OPT, 1,
-                                    ESF_DZ_TX_OPTION_TYPE,
-                                    ESE_DZ_TX_OPTION_DESC_TSO,
-                                    ESF_DZ_TX_TSO_TCP_FLAGS, tcp_flags,
-                                    ESF_DZ_TX_TSO_IP_ID, st->ipv4_id,
-                                    ESF_DZ_TX_TSO_TCP_SEQNO, st->seqnum);
-               ++tx_queue->insert_count;
-
-               /* We mapped the headers in tso_start().  Unmap them
-                * when the last segment is completed.
-                */
-               buffer = efx_tx_queue_get_insert_buffer(tx_queue);
-               buffer->dma_addr = st->header_dma_addr;
-               buffer->len = st->header_len;
-               if (is_last) {
-                       buffer->flags = EFX_TX_BUF_CONT | EFX_TX_BUF_MAP_SINGLE;
-                       buffer->unmap_len = st->header_unmap_len;
-                       buffer->dma_offset = 0;
-                       /* Ensure we only unmap them once in case of a
-                        * later DMA mapping error and rollback
-                        */
-                       st->header_unmap_len = 0;
-               } else {
-                       buffer->flags = EFX_TX_BUF_CONT;
-                       buffer->unmap_len = 0;
-               }
-               ++tx_queue->insert_count;
-       }
-
-       st->seqnum += skb_shinfo(skb)->gso_size;
-
-       /* Linux leaves suitable gaps in the IP ID space for us to fill. */
-       ++st->ipv4_id;
-
-       ++tx_queue->tso_packets;
-
-       ++tx_queue->tx_packets;
-
-       return 0;
-}
-
-
-/**
- * efx_enqueue_skb_tso - segment and transmit a TSO socket buffer
- * @tx_queue:          Efx TX queue
- * @skb:               Socket buffer
- *
- * Context: You must hold netif_tx_lock() to call this function.
- *
- * Add socket buffer @skb to @tx_queue, doing TSO or return != 0 if
- * @skb was not enqueued.  In all cases @skb is consumed.  Return
- * %NETDEV_TX_OK.
- */
-static int efx_enqueue_skb_tso(struct efx_tx_queue *tx_queue,
-                              struct sk_buff *skb)
-{
-       struct efx_nic *efx = tx_queue->efx;
-       unsigned int old_insert_count = tx_queue->insert_count;
-       int frag_i, rc;
-       struct tso_state state;
-
-       /* Find the packet protocol and sanity-check it */
-       state.protocol = efx_tso_check_protocol(skb);
-
-       rc = tso_start(&state, efx, tx_queue, skb);
-       if (rc)
-               goto mem_err;
-
-       if (likely(state.in_len == 0)) {
-               /* Grab the first payload fragment. */
-               EFX_BUG_ON_PARANOID(skb_shinfo(skb)->nr_frags < 1);
-               frag_i = 0;
-               rc = tso_get_fragment(&state, efx,
-                                     skb_shinfo(skb)->frags + frag_i);
-               if (rc)
-                       goto mem_err;
-       } else {
-               /* Payload starts in the header area. */
-               frag_i = -1;
-       }
-
-       if (tso_start_new_packet(tx_queue, skb, &state) < 0)
-               goto mem_err;
-
-       while (1) {
-               tso_fill_packet_with_fragment(tx_queue, skb, &state);
-
-               /* Move onto the next fragment? */
-               if (state.in_len == 0) {
-                       if (++frag_i >= skb_shinfo(skb)->nr_frags)
-                               /* End of payload reached. */
-                               break;
-                       rc = tso_get_fragment(&state, efx,
-                                             skb_shinfo(skb)->frags + frag_i);
-                       if (rc)
-                               goto mem_err;
-               }
-
-               /* Start at new packet? */
-               if (state.packet_space == 0 &&
-                   tso_start_new_packet(tx_queue, skb, &state) < 0)
-                       goto mem_err;
-       }
-
-       netdev_tx_sent_queue(tx_queue->core_txq, skb->len);
-
-       efx_tx_maybe_stop_queue(tx_queue);
-
-       /* Pass off to hardware */
-       if (!skb->xmit_more || netif_xmit_stopped(tx_queue->core_txq)) {
-               struct efx_tx_queue *txq2 = efx_tx_queue_partner(tx_queue);
-
-               /* There could be packets left on the partner queue if those
-                * SKBs had skb->xmit_more set. If we do not push those they
-                * could be left for a long time and cause a netdev watchdog.
-                */
-               if (txq2->xmit_more_available)
-                       efx_nic_push_buffers(txq2);
-
-               efx_nic_push_buffers(tx_queue);
-       } else {
-               tx_queue->xmit_more_available = skb->xmit_more;
-       }
-
-       tx_queue->tso_bursts++;
-       return NETDEV_TX_OK;
-
- mem_err:
-       netif_err(efx, tx_err, efx->net_dev,
-                 "Out of memory for TSO headers, or DMA mapping error\n");
-       dev_kfree_skb_any(skb);
-
-       /* Free the DMA mapping we were in the process of writing out */
-       if (state.unmap_len) {
-               if (state.dma_flags & EFX_TX_BUF_MAP_SINGLE)
-                       dma_unmap_single(&efx->pci_dev->dev, state.unmap_addr,
-                                        state.unmap_len, DMA_TO_DEVICE);
-               else
-                       dma_unmap_page(&efx->pci_dev->dev, state.unmap_addr,
-                                      state.unmap_len, DMA_TO_DEVICE);
-       }
-
-       /* Free the header DMA mapping, if using option descriptors */
-       if (state.header_unmap_len)
-               dma_unmap_single(&efx->pci_dev->dev, state.header_dma_addr,
-                                state.header_unmap_len, DMA_TO_DEVICE);
-
-       efx_enqueue_unwind(tx_queue, old_insert_count);
-       return NETDEV_TX_OK;
-}
diff --git a/drivers/net/ethernet/sfc/tx.h b/drivers/net/ethernet/sfc/tx.h
new file mode 100644 (file)
index 0000000..1cccc97
--- /dev/null
@@ -0,0 +1,27 @@
+/****************************************************************************
+ * Driver for Solarflare network controllers and boards
+ * Copyright 2005-2006 Fen Systems Ltd.
+ * Copyright 2006-2015 Solarflare Communications Inc.
+ *
+ * This program is free software; you can redistribute it and/or modify it
+ * under the terms of the GNU General Public License version 2 as published
+ * by the Free Software Foundation, incorporated herein by reference.
+ */
+
+#ifndef EFX_TX_H
+#define EFX_TX_H
+
+#include <linux/types.h>
+
+/* Driver internal tx-path related declarations. */
+
+unsigned int efx_tx_limit_len(struct efx_tx_queue *tx_queue,
+                             dma_addr_t dma_addr, unsigned int len);
+
+u8 *efx_tx_get_copy_buffer_limited(struct efx_tx_queue *tx_queue,
+                                  struct efx_tx_buffer *buffer, size_t len);
+
+int efx_enqueue_skb_tso(struct efx_tx_queue *tx_queue, struct sk_buff *skb,
+                       bool *data_mapped);
+
+#endif /* EFX_TX_H */
diff --git a/drivers/net/ethernet/sfc/tx_tso.c b/drivers/net/ethernet/sfc/tx_tso.c
new file mode 100644 (file)
index 0000000..99936d7
--- /dev/null
@@ -0,0 +1,570 @@
+/****************************************************************************
+ * Driver for Solarflare network controllers and boards
+ * Copyright 2005-2006 Fen Systems Ltd.
+ * Copyright 2005-2015 Solarflare Communications Inc.
+ *
+ * This program is free software; you can redistribute it and/or modify it
+ * under the terms of the GNU General Public License version 2 as published
+ * by the Free Software Foundation, incorporated herein by reference.
+ */
+
+#include <linux/pci.h>
+#include <linux/tcp.h>
+#include <linux/ip.h>
+#include <linux/in.h>
+#include <linux/ipv6.h>
+#include <linux/slab.h>
+#include <net/ipv6.h>
+#include <linux/if_ether.h>
+#include <linux/highmem.h>
+#include <linux/moduleparam.h>
+#include <linux/cache.h>
+#include "net_driver.h"
+#include "efx.h"
+#include "io.h"
+#include "nic.h"
+#include "tx.h"
+#include "workarounds.h"
+#include "ef10_regs.h"
+
+/* Efx legacy TCP segmentation acceleration.
+ *
+ * Why?  Because by doing it here in the driver we can go significantly
+ * faster than the GSO.
+ *
+ * Requires TX checksum offload support.
+ */
+
+#define PTR_DIFF(p1, p2)  ((u8 *)(p1) - (u8 *)(p2))
+
+/**
+ * struct tso_state - TSO state for an SKB
+ * @out_len: Remaining length in current segment
+ * @seqnum: Current sequence number
+ * @ipv4_id: Current IPv4 ID, host endian
+ * @packet_space: Remaining space in current packet
+ * @dma_addr: DMA address of current position
+ * @in_len: Remaining length in current SKB fragment
+ * @unmap_len: Length of SKB fragment
+ * @unmap_addr: DMA address of SKB fragment
+ * @dma_flags: TX buffer flags for DMA mapping - %EFX_TX_BUF_MAP_SINGLE or 0
+ * @protocol: Network protocol (after any VLAN header)
+ * @ip_off: Offset of IP header
+ * @tcp_off: Offset of TCP header
+ * @header_len: Number of bytes of header
+ * @ip_base_len: IPv4 tot_len or IPv6 payload_len, before TCP payload
+ * @header_dma_addr: Header DMA address, when using option descriptors
+ * @header_unmap_len: Header DMA mapped length, or 0 if not using option
+ *     descriptors
+ *
+ * The state used during segmentation.  It is put into this data structure
+ * just to make it easy to pass into inline functions.
+ */
+struct tso_state {
+       /* Output position */
+       unsigned int out_len;
+       unsigned int seqnum;
+       u16 ipv4_id;
+       unsigned int packet_space;
+
+       /* Input position */
+       dma_addr_t dma_addr;
+       unsigned int in_len;
+       unsigned int unmap_len;
+       dma_addr_t unmap_addr;
+       unsigned short dma_flags;
+
+       __be16 protocol;
+       unsigned int ip_off;
+       unsigned int tcp_off;
+       unsigned int header_len;
+       unsigned int ip_base_len;
+       dma_addr_t header_dma_addr;
+       unsigned int header_unmap_len;
+};
+
+static inline void prefetch_ptr(struct efx_tx_queue *tx_queue)
+{
+       unsigned int insert_ptr = efx_tx_queue_get_insert_index(tx_queue);
+       char *ptr;
+
+       ptr = (char *) (tx_queue->buffer + insert_ptr);
+       prefetch(ptr);
+       prefetch(ptr + 0x80);
+
+       ptr = (char *) (((efx_qword_t *)tx_queue->txd.buf.addr) + insert_ptr);
+       prefetch(ptr);
+       prefetch(ptr + 0x80);
+}
+
+/**
+ * efx_tx_queue_insert - push descriptors onto the TX queue
+ * @tx_queue:          Efx TX queue
+ * @dma_addr:          DMA address of fragment
+ * @len:               Length of fragment
+ * @final_buffer:      The final buffer inserted into the queue
+ *
+ * Push descriptors onto the TX queue.
+ */
+static void efx_tx_queue_insert(struct efx_tx_queue *tx_queue,
+                               dma_addr_t dma_addr, unsigned int len,
+                               struct efx_tx_buffer **final_buffer)
+{
+       struct efx_tx_buffer *buffer;
+       unsigned int dma_len;
+
+       EFX_BUG_ON_PARANOID(len <= 0);
+
+       while (1) {
+               buffer = efx_tx_queue_get_insert_buffer(tx_queue);
+               ++tx_queue->insert_count;
+
+               EFX_BUG_ON_PARANOID(tx_queue->insert_count -
+                                   tx_queue->read_count >=
+                                   tx_queue->efx->txq_entries);
+
+               buffer->dma_addr = dma_addr;
+
+               dma_len = tx_queue->efx->type->tx_limit_len(tx_queue,
+                               dma_addr, len);
+
+               /* If there's space for everything this is our last buffer. */
+               if (dma_len >= len)
+                       break;
+
+               buffer->len = dma_len;
+               buffer->flags = EFX_TX_BUF_CONT;
+               dma_addr += dma_len;
+               len -= dma_len;
+       }
+
+       EFX_BUG_ON_PARANOID(!len);
+       buffer->len = len;
+       *final_buffer = buffer;
+}
+
+/*
+ * Verify that our various assumptions about sk_buffs and the conditions
+ * under which TSO will be attempted hold true.  Return the protocol number.
+ */
+static __be16 efx_tso_check_protocol(struct sk_buff *skb)
+{
+       __be16 protocol = skb->protocol;
+
+       EFX_BUG_ON_PARANOID(((struct ethhdr *)skb->data)->h_proto !=
+                           protocol);
+       if (protocol == htons(ETH_P_8021Q)) {
+               struct vlan_ethhdr *veh = (struct vlan_ethhdr *)skb->data;
+
+               protocol = veh->h_vlan_encapsulated_proto;
+       }
+
+       if (protocol == htons(ETH_P_IP)) {
+               EFX_BUG_ON_PARANOID(ip_hdr(skb)->protocol != IPPROTO_TCP);
+       } else {
+               EFX_BUG_ON_PARANOID(protocol != htons(ETH_P_IPV6));
+               EFX_BUG_ON_PARANOID(ipv6_hdr(skb)->nexthdr != NEXTHDR_TCP);
+       }
+       EFX_BUG_ON_PARANOID((PTR_DIFF(tcp_hdr(skb), skb->data)
+                            + (tcp_hdr(skb)->doff << 2u)) >
+                           skb_headlen(skb));
+
+       return protocol;
+}
+
+static u8 *efx_tsoh_get_buffer(struct efx_tx_queue *tx_queue,
+                              struct efx_tx_buffer *buffer, unsigned int len)
+{
+       u8 *result;
+
+       EFX_BUG_ON_PARANOID(buffer->len);
+       EFX_BUG_ON_PARANOID(buffer->flags);
+       EFX_BUG_ON_PARANOID(buffer->unmap_len);
+
+       result = efx_tx_get_copy_buffer_limited(tx_queue, buffer, len);
+
+       if (result) {
+               buffer->flags = EFX_TX_BUF_CONT;
+       } else {
+               buffer->heap_buf = kmalloc(NET_IP_ALIGN + len, GFP_ATOMIC);
+               if (unlikely(!buffer->heap_buf))
+                       return NULL;
+               tx_queue->tso_long_headers++;
+               result = (u8 *)buffer->heap_buf + NET_IP_ALIGN;
+               buffer->flags = EFX_TX_BUF_CONT | EFX_TX_BUF_HEAP;
+       }
+
+       buffer->len = len;
+
+       return result;
+}
+
+/*
+ * Put a TSO header into the TX queue.
+ *
+ * This is special-cased because we know that it is small enough to fit in
+ * a single fragment, and we know it doesn't cross a page boundary.  It
+ * also allows us to not worry about end-of-packet etc.
+ */
+static int efx_tso_put_header(struct efx_tx_queue *tx_queue,
+                             struct efx_tx_buffer *buffer, u8 *header)
+{
+       if (unlikely(buffer->flags & EFX_TX_BUF_HEAP)) {
+               buffer->dma_addr = dma_map_single(&tx_queue->efx->pci_dev->dev,
+                                                 header, buffer->len,
+                                                 DMA_TO_DEVICE);
+               if (unlikely(dma_mapping_error(&tx_queue->efx->pci_dev->dev,
+                                              buffer->dma_addr))) {
+                       kfree(buffer->heap_buf);
+                       buffer->len = 0;
+                       buffer->flags = 0;
+                       return -ENOMEM;
+               }
+               buffer->unmap_len = buffer->len;
+               buffer->dma_offset = 0;
+               buffer->flags |= EFX_TX_BUF_MAP_SINGLE;
+       }
+
+       ++tx_queue->insert_count;
+       return 0;
+}
+
+
+/* Parse the SKB header and initialise state. */
+static int tso_start(struct tso_state *st, struct efx_nic *efx,
+                    struct efx_tx_queue *tx_queue,
+                    const struct sk_buff *skb)
+{
+       struct device *dma_dev = &efx->pci_dev->dev;
+       unsigned int header_len, in_len;
+       bool use_opt_desc = false;
+       dma_addr_t dma_addr;
+
+       if (tx_queue->tso_version == 1)
+               use_opt_desc = true;
+
+       st->ip_off = skb_network_header(skb) - skb->data;
+       st->tcp_off = skb_transport_header(skb) - skb->data;
+       header_len = st->tcp_off + (tcp_hdr(skb)->doff << 2u);
+       in_len = skb_headlen(skb) - header_len;
+       st->header_len = header_len;
+       st->in_len = in_len;
+       if (st->protocol == htons(ETH_P_IP)) {
+               st->ip_base_len = st->header_len - st->ip_off;
+               st->ipv4_id = ntohs(ip_hdr(skb)->id);
+       } else {
+               st->ip_base_len = st->header_len - st->tcp_off;
+               st->ipv4_id = 0;
+       }
+       st->seqnum = ntohl(tcp_hdr(skb)->seq);
+
+       EFX_BUG_ON_PARANOID(tcp_hdr(skb)->urg);
+       EFX_BUG_ON_PARANOID(tcp_hdr(skb)->syn);
+       EFX_BUG_ON_PARANOID(tcp_hdr(skb)->rst);
+
+       st->out_len = skb->len - header_len;
+
+       if (!use_opt_desc) {
+               st->header_unmap_len = 0;
+
+               if (likely(in_len == 0)) {
+                       st->dma_flags = 0;
+                       st->unmap_len = 0;
+                       return 0;
+               }
+
+               dma_addr = dma_map_single(dma_dev, skb->data + header_len,
+                                         in_len, DMA_TO_DEVICE);
+               st->dma_flags = EFX_TX_BUF_MAP_SINGLE;
+               st->dma_addr = dma_addr;
+               st->unmap_addr = dma_addr;
+               st->unmap_len = in_len;
+       } else {
+               dma_addr = dma_map_single(dma_dev, skb->data,
+                                         skb_headlen(skb), DMA_TO_DEVICE);
+               st->header_dma_addr = dma_addr;
+               st->header_unmap_len = skb_headlen(skb);
+               st->dma_flags = 0;
+               st->dma_addr = dma_addr + header_len;
+               st->unmap_len = 0;
+       }
+
+       return unlikely(dma_mapping_error(dma_dev, dma_addr)) ? -ENOMEM : 0;
+}
+
+static int tso_get_fragment(struct tso_state *st, struct efx_nic *efx,
+                           skb_frag_t *frag)
+{
+       st->unmap_addr = skb_frag_dma_map(&efx->pci_dev->dev, frag, 0,
+                                         skb_frag_size(frag), DMA_TO_DEVICE);
+       if (likely(!dma_mapping_error(&efx->pci_dev->dev, st->unmap_addr))) {
+               st->dma_flags = 0;
+               st->unmap_len = skb_frag_size(frag);
+               st->in_len = skb_frag_size(frag);
+               st->dma_addr = st->unmap_addr;
+               return 0;
+       }
+       return -ENOMEM;
+}
+
+
+/**
+ * tso_fill_packet_with_fragment - form descriptors for the current fragment
+ * @tx_queue:          Efx TX queue
+ * @skb:               Socket buffer
+ * @st:                        TSO state
+ *
+ * Form descriptors for the current fragment, until we reach the end
+ * of fragment or end-of-packet.
+ */
+static void tso_fill_packet_with_fragment(struct efx_tx_queue *tx_queue,
+                                         const struct sk_buff *skb,
+                                         struct tso_state *st)
+{
+       struct efx_tx_buffer *buffer;
+       int n;
+
+       if (st->in_len == 0)
+               return;
+       if (st->packet_space == 0)
+               return;
+
+       EFX_BUG_ON_PARANOID(st->in_len <= 0);
+       EFX_BUG_ON_PARANOID(st->packet_space <= 0);
+
+       n = min(st->in_len, st->packet_space);
+
+       st->packet_space -= n;
+       st->out_len -= n;
+       st->in_len -= n;
+
+       efx_tx_queue_insert(tx_queue, st->dma_addr, n, &buffer);
+
+       if (st->out_len == 0) {
+               /* Transfer ownership of the skb */
+               buffer->skb = skb;
+               buffer->flags = EFX_TX_BUF_SKB;
+       } else if (st->packet_space != 0) {
+               buffer->flags = EFX_TX_BUF_CONT;
+       }
+
+       if (st->in_len == 0) {
+               /* Transfer ownership of the DMA mapping */
+               buffer->unmap_len = st->unmap_len;
+               buffer->dma_offset = buffer->unmap_len - buffer->len;
+               buffer->flags |= st->dma_flags;
+               st->unmap_len = 0;
+       }
+
+       st->dma_addr += n;
+}
+
+
+#define TCP_FLAGS_OFFSET 13
+
+/**
+ * tso_start_new_packet - generate a new header and prepare for the new packet
+ * @tx_queue:          Efx TX queue
+ * @skb:               Socket buffer
+ * @st:                        TSO state
+ *
+ * Generate a new header and prepare for the new packet.  Return 0 on
+ * success, or -%ENOMEM if failed to alloc header.
+ */
+static int tso_start_new_packet(struct efx_tx_queue *tx_queue,
+                               const struct sk_buff *skb,
+                               struct tso_state *st)
+{
+       struct efx_tx_buffer *buffer =
+               efx_tx_queue_get_insert_buffer(tx_queue);
+       bool is_last = st->out_len <= skb_shinfo(skb)->gso_size;
+       u8 tcp_flags_mask;
+
+       if (!is_last) {
+               st->packet_space = skb_shinfo(skb)->gso_size;
+               tcp_flags_mask = 0x09; /* mask out FIN and PSH */
+       } else {
+               st->packet_space = st->out_len;
+               tcp_flags_mask = 0x00;
+       }
+
+       if (!st->header_unmap_len) {
+               /* Allocate and insert a DMA-mapped header buffer. */
+               struct tcphdr *tsoh_th;
+               unsigned int ip_length;
+               u8 *header;
+               int rc;
+
+               header = efx_tsoh_get_buffer(tx_queue, buffer, st->header_len);
+               if (!header)
+                       return -ENOMEM;
+
+               tsoh_th = (struct tcphdr *)(header + st->tcp_off);
+
+               /* Copy and update the headers. */
+               memcpy(header, skb->data, st->header_len);
+
+               tsoh_th->seq = htonl(st->seqnum);
+               ((u8 *)tsoh_th)[TCP_FLAGS_OFFSET] &= ~tcp_flags_mask;
+
+               ip_length = st->ip_base_len + st->packet_space;
+
+               if (st->protocol == htons(ETH_P_IP)) {
+                       struct iphdr *tsoh_iph =
+                               (struct iphdr *)(header + st->ip_off);
+
+                       tsoh_iph->tot_len = htons(ip_length);
+                       tsoh_iph->id = htons(st->ipv4_id);
+               } else {
+                       struct ipv6hdr *tsoh_iph =
+                               (struct ipv6hdr *)(header + st->ip_off);
+
+                       tsoh_iph->payload_len = htons(ip_length);
+               }
+
+               rc = efx_tso_put_header(tx_queue, buffer, header);
+               if (unlikely(rc))
+                       return rc;
+       } else {
+               /* Send the original headers with a TSO option descriptor
+                * in front
+                */
+               u8 tcp_flags = ((u8 *)tcp_hdr(skb))[TCP_FLAGS_OFFSET] &
+                               ~tcp_flags_mask;
+
+               buffer->flags = EFX_TX_BUF_OPTION;
+               buffer->len = 0;
+               buffer->unmap_len = 0;
+               EFX_POPULATE_QWORD_5(buffer->option,
+                                    ESF_DZ_TX_DESC_IS_OPT, 1,
+                                    ESF_DZ_TX_OPTION_TYPE,
+                                    ESE_DZ_TX_OPTION_DESC_TSO,
+                                    ESF_DZ_TX_TSO_TCP_FLAGS, tcp_flags,
+                                    ESF_DZ_TX_TSO_IP_ID, st->ipv4_id,
+                                    ESF_DZ_TX_TSO_TCP_SEQNO, st->seqnum);
+               ++tx_queue->insert_count;
+
+               /* We mapped the headers in tso_start().  Unmap them
+                * when the last segment is completed.
+                */
+               buffer = efx_tx_queue_get_insert_buffer(tx_queue);
+               buffer->dma_addr = st->header_dma_addr;
+               buffer->len = st->header_len;
+               if (is_last) {
+                       buffer->flags = EFX_TX_BUF_CONT | EFX_TX_BUF_MAP_SINGLE;
+                       buffer->unmap_len = st->header_unmap_len;
+                       buffer->dma_offset = 0;
+                       /* Ensure we only unmap them once in case of a
+                        * later DMA mapping error and rollback
+                        */
+                       st->header_unmap_len = 0;
+               } else {
+                       buffer->flags = EFX_TX_BUF_CONT;
+                       buffer->unmap_len = 0;
+               }
+               ++tx_queue->insert_count;
+       }
+
+       st->seqnum += skb_shinfo(skb)->gso_size;
+
+       /* Linux leaves suitable gaps in the IP ID space for us to fill. */
+       ++st->ipv4_id;
+
+       return 0;
+}
+
+/**
+ * efx_enqueue_skb_tso - segment and transmit a TSO socket buffer
+ * @tx_queue:          Efx TX queue
+ * @skb:               Socket buffer
+ * @data_mapped:        Did we map the data? Always set to true
+ *                      by this on success.
+ *
+ * Context: You must hold netif_tx_lock() to call this function.
+ *
+ * Add socket buffer @skb to @tx_queue, doing TSO or return != 0 if
+ * @skb was not enqueued.  In all cases @skb is consumed.  Return
+ * %NETDEV_TX_OK.
+ */
+int efx_enqueue_skb_tso(struct efx_tx_queue *tx_queue,
+                       struct sk_buff *skb,
+                       bool *data_mapped)
+{
+       struct efx_nic *efx = tx_queue->efx;
+       int frag_i, rc;
+       struct tso_state state;
+
+       prefetch(skb->data);
+
+       /* Find the packet protocol and sanity-check it */
+       state.protocol = efx_tso_check_protocol(skb);
+
+       EFX_BUG_ON_PARANOID(tx_queue->write_count != tx_queue->insert_count);
+
+       rc = tso_start(&state, efx, tx_queue, skb);
+       if (rc)
+               goto mem_err;
+
+       if (likely(state.in_len == 0)) {
+               /* Grab the first payload fragment. */
+               EFX_BUG_ON_PARANOID(skb_shinfo(skb)->nr_frags < 1);
+               frag_i = 0;
+               rc = tso_get_fragment(&state, efx,
+                                     skb_shinfo(skb)->frags + frag_i);
+               if (rc)
+                       goto mem_err;
+       } else {
+               /* Payload starts in the header area. */
+               frag_i = -1;
+       }
+
+       if (tso_start_new_packet(tx_queue, skb, &state) < 0)
+               goto mem_err;
+
+       prefetch_ptr(tx_queue);
+
+       while (1) {
+               tso_fill_packet_with_fragment(tx_queue, skb, &state);
+
+               /* Move onto the next fragment? */
+               if (state.in_len == 0) {
+                       if (++frag_i >= skb_shinfo(skb)->nr_frags)
+                               /* End of payload reached. */
+                               break;
+                       rc = tso_get_fragment(&state, efx,
+                                             skb_shinfo(skb)->frags + frag_i);
+                       if (rc)
+                               goto mem_err;
+               }
+
+               /* Start at new packet? */
+               if (state.packet_space == 0 &&
+                   tso_start_new_packet(tx_queue, skb, &state) < 0)
+                       goto mem_err;
+       }
+
+       *data_mapped = true;
+
+       return 0;
+
+ mem_err:
+       netif_err(efx, tx_err, efx->net_dev,
+                 "Out of memory for TSO headers, or DMA mapping error\n");
+
+       /* Free the DMA mapping we were in the process of writing out */
+       if (state.unmap_len) {
+               if (state.dma_flags & EFX_TX_BUF_MAP_SINGLE)
+                       dma_unmap_single(&efx->pci_dev->dev, state.unmap_addr,
+                                        state.unmap_len, DMA_TO_DEVICE);
+               else
+                       dma_unmap_page(&efx->pci_dev->dev, state.unmap_addr,
+                                      state.unmap_len, DMA_TO_DEVICE);
+       }
+
+       /* Free the header DMA mapping, if using option descriptors */
+       if (state.header_unmap_len)
+               dma_unmap_single(&efx->pci_dev->dev, state.header_dma_addr,
+                                state.header_unmap_len, DMA_TO_DEVICE);
+
+       return -ENOMEM;
+}