Merge branch 'irq-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel...

[deliverable/linux.git] / drivers / net / ethernet / mellanox / mlx4 / en_tx.c

/*
 * Copyright (c) 2007 Mellanox Technologies. All rights reserved.
 *
 * This software is available to you under a choice of one of two
 * licenses.  You may choose to be licensed under the terms of the GNU
 * General Public License (GPL) Version 2, available from the file
 * COPYING in the main directory of this source tree, or the
 * OpenIB.org BSD license below:
 *
 *     Redistribution and use in source and binary forms, with or
 *     without modification, are permitted provided that the following
 *     conditions are met:
 *
 *      - Redistributions of source code must retain the above
 *        copyright notice, this list of conditions and the following
 *        disclaimer.
 *
 *      - Redistributions in binary form must reproduce the above
 *        copyright notice, this list of conditions and the following
 *        disclaimer in the documentation and/or other materials
 *        provided with the distribution.
 *
 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
 * EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
 * MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
 * NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS
 * BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN
 * ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN
 * CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
 * SOFTWARE.
 *
 */

#include <asm/page.h>
#include <linux/mlx4/cq.h>
#include <linux/slab.h>
#include <linux/mlx4/qp.h>
#include <linux/skbuff.h>
#include <linux/if_vlan.h>
#include <linux/vmalloc.h>
#include <linux/tcp.h>
#include <linux/moduleparam.h>

#include "mlx4_en.h"

enum {
        MAX_INLINE = 104, /* 128 - 16 - 4 - 4 */
        MAX_BF = 256,
};

static int inline_thold __read_mostly = MAX_INLINE;

module_param_named(inline_thold, inline_thold, int, 0444);
MODULE_PARM_DESC(inline_thold, "threshold for using inline data");

int mlx4_en_create_tx_ring(struct mlx4_en_priv *priv,
                           struct mlx4_en_tx_ring **pring, int qpn, u32 size,
                           u16 stride, int node)
{
        struct mlx4_en_dev *mdev = priv->mdev;
        struct mlx4_en_tx_ring *ring;
        int tmp;
        int err;

        ring = kzalloc_node(sizeof(*ring), GFP_KERNEL, node);
        if (!ring) {
                ring = kzalloc(sizeof(*ring), GFP_KERNEL);
                if (!ring) {
                        en_err(priv, "Failed allocating TX ring\n");
                        return -ENOMEM;
                }
        }

        ring->size = size;
        ring->size_mask = size - 1;
        ring->stride = stride;

        inline_thold = min(inline_thold, MAX_INLINE);

        tmp = size * sizeof(struct mlx4_en_tx_info);
        ring->tx_info = vmalloc_node(tmp, node);
        if (!ring->tx_info) {
                ring->tx_info = vmalloc(tmp);
                if (!ring->tx_info) {
                        err = -ENOMEM;
                        goto err_ring;
                }
        }

        en_dbg(DRV, priv, "Allocated tx_info ring at addr:%p size:%d\n",
                 ring->tx_info, tmp);

        ring->bounce_buf = kmalloc_node(MAX_DESC_SIZE, GFP_KERNEL, node);
        if (!ring->bounce_buf) {
                ring->bounce_buf = kmalloc(MAX_DESC_SIZE, GFP_KERNEL);
                if (!ring->bounce_buf) {
                        err = -ENOMEM;
                        goto err_info;
                }
        }
        ring->buf_size = ALIGN(size * ring->stride, MLX4_EN_PAGE_SIZE);

        /* Allocate HW buffers on provided NUMA node */
        set_dev_node(&mdev->dev->pdev->dev, node);
        err = mlx4_alloc_hwq_res(mdev->dev, &ring->wqres, ring->buf_size,
                                 2 * PAGE_SIZE);
        set_dev_node(&mdev->dev->pdev->dev, mdev->dev->numa_node);
        if (err) {
                en_err(priv, "Failed allocating hwq resources\n");
                goto err_bounce;
        }

        err = mlx4_en_map_buffer(&ring->wqres.buf);
        if (err) {
                en_err(priv, "Failed to map TX buffer\n");
                goto err_hwq_res;
        }

        ring->buf = ring->wqres.buf.direct.buf;

        en_dbg(DRV, priv, "Allocated TX ring (addr:%p) - buf:%p size:%d "
               "buf_size:%d dma:%llx\n", ring, ring->buf, ring->size,
               ring->buf_size, (unsigned long long) ring->wqres.buf.direct.map);

        ring->qpn = qpn;
        err = mlx4_qp_alloc(mdev->dev, ring->qpn, &ring->qp);
        if (err) {
                en_err(priv, "Failed allocating qp %d\n", ring->qpn);
                goto err_map;
        }
        ring->qp.event = mlx4_en_sqp_event;

        err = mlx4_bf_alloc(mdev->dev, &ring->bf, node);
        if (err) {
                en_dbg(DRV, priv, "working without blueflame (%d)", err);
                ring->bf.uar = &mdev->priv_uar;
                ring->bf.uar->map = mdev->uar_map;
                ring->bf_enabled = false;
        } else
                ring->bf_enabled = true;

        ring->hwtstamp_tx_type = priv->hwtstamp_config.tx_type;

        *pring = ring;
        return 0;

err_map:
        mlx4_en_unmap_buffer(&ring->wqres.buf);
err_hwq_res:
        mlx4_free_hwq_res(mdev->dev, &ring->wqres, ring->buf_size);
err_bounce:
        kfree(ring->bounce_buf);
        ring->bounce_buf = NULL;
err_info:
        vfree(ring->tx_info);
        ring->tx_info = NULL;
err_ring:
        kfree(ring);
        *pring = NULL;
        return err;
}

void mlx4_en_destroy_tx_ring(struct mlx4_en_priv *priv,
                             struct mlx4_en_tx_ring **pring)
{
        struct mlx4_en_dev *mdev = priv->mdev;
        struct mlx4_en_tx_ring *ring = *pring;
        en_dbg(DRV, priv, "Destroying tx ring, qpn: %d\n", ring->qpn);

        if (ring->bf_enabled)
                mlx4_bf_free(mdev->dev, &ring->bf);
        mlx4_qp_remove(mdev->dev, &ring->qp);
        mlx4_qp_free(mdev->dev, &ring->qp);
        mlx4_en_unmap_buffer(&ring->wqres.buf);
        mlx4_free_hwq_res(mdev->dev, &ring->wqres, ring->buf_size);
        kfree(ring->bounce_buf);
        ring->bounce_buf = NULL;
        vfree(ring->tx_info);
        ring->tx_info = NULL;
        kfree(ring);
        *pring = NULL;
}

int mlx4_en_activate_tx_ring(struct mlx4_en_priv *priv,
                             struct mlx4_en_tx_ring *ring,
                             int cq, int user_prio)
{
        struct mlx4_en_dev *mdev = priv->mdev;
        int err;

        ring->cqn = cq;
        ring->prod = 0;
        ring->cons = 0xffffffff;
        ring->last_nr_txbb = 1;
        ring->poll_cnt = 0;
        memset(ring->tx_info, 0, ring->size * sizeof(struct mlx4_en_tx_info));
        memset(ring->buf, 0, ring->buf_size);

        ring->qp_state = MLX4_QP_STATE_RST;
        ring->doorbell_qpn = ring->qp.qpn << 8;

        mlx4_en_fill_qp_context(priv, ring->size, ring->stride, 1, 0, ring->qpn,
                                ring->cqn, user_prio, &ring->context);
        if (ring->bf_enabled)
                ring->context.usr_page = cpu_to_be32(ring->bf.uar->index);

        err = mlx4_qp_to_ready(mdev->dev, &ring->wqres.mtt, &ring->context,
                               &ring->qp, &ring->qp_state);

        return err;
}

void mlx4_en_deactivate_tx_ring(struct mlx4_en_priv *priv,
                                struct mlx4_en_tx_ring *ring)
{
        struct mlx4_en_dev *mdev = priv->mdev;

        mlx4_qp_modify(mdev->dev, NULL, ring->qp_state,
                       MLX4_QP_STATE_RST, NULL, 0, 0, &ring->qp);
}

static void mlx4_en_stamp_wqe(struct mlx4_en_priv *priv,
                              struct mlx4_en_tx_ring *ring, int index,
                              u8 owner)
{
        __be32 stamp = cpu_to_be32(STAMP_VAL | (!!owner << STAMP_SHIFT));
        struct mlx4_en_tx_desc *tx_desc = ring->buf + index * TXBB_SIZE;
        struct mlx4_en_tx_info *tx_info = &ring->tx_info[index];
        void *end = ring->buf + ring->buf_size;
        __be32 *ptr = (__be32 *)tx_desc;
        int i;

        /* Optimize the common case when there are no wraparounds */
        if (likely((void *)tx_desc + tx_info->nr_txbb * TXBB_SIZE <= end)) {
                /* Stamp the freed descriptor */
                for (i = 0; i < tx_info->nr_txbb * TXBB_SIZE;
                     i += STAMP_STRIDE) {
                        *ptr = stamp;
                        ptr += STAMP_DWORDS;
                }
        } else {
                /* Stamp the freed descriptor */
                for (i = 0; i < tx_info->nr_txbb * TXBB_SIZE;
                     i += STAMP_STRIDE) {
                        *ptr = stamp;
                        ptr += STAMP_DWORDS;
                        if ((void *)ptr >= end) {
                                ptr = ring->buf;
                                stamp ^= cpu_to_be32(0x80000000);
                        }
                }
        }
}


static u32 mlx4_en_free_tx_desc(struct mlx4_en_priv *priv,
                                struct mlx4_en_tx_ring *ring,
                                int index, u8 owner, u64 timestamp)
{
        struct mlx4_en_dev *mdev = priv->mdev;
        struct mlx4_en_tx_info *tx_info = &ring->tx_info[index];
        struct mlx4_en_tx_desc *tx_desc = ring->buf + index * TXBB_SIZE;
        struct mlx4_wqe_data_seg *data = (void *) tx_desc + tx_info->data_offset;
        struct sk_buff *skb = tx_info->skb;
        struct skb_frag_struct *frag;
        void *end = ring->buf + ring->buf_size;
        int frags = skb_shinfo(skb)->nr_frags;
        int i;
        struct skb_shared_hwtstamps hwts;

        if (timestamp) {
                mlx4_en_fill_hwtstamps(mdev, &hwts, timestamp);
                skb_tstamp_tx(skb, &hwts);
        }

        /* Optimize the common case when there are no wraparounds */
        if (likely((void *) tx_desc + tx_info->nr_txbb * TXBB_SIZE <= end)) {
                if (!tx_info->inl) {
                        if (tx_info->linear) {
                                dma_unmap_single(priv->ddev,
                                        (dma_addr_t) be64_to_cpu(data->addr),
                                         be32_to_cpu(data->byte_count),
                                         PCI_DMA_TODEVICE);
                                ++data;
                        }

                        for (i = 0; i < frags; i++) {
                                frag = &skb_shinfo(skb)->frags[i];
                                dma_unmap_page(priv->ddev,
                                        (dma_addr_t) be64_to_cpu(data[i].addr),
                                        skb_frag_size(frag), PCI_DMA_TODEVICE);
                        }
                }
        } else {
                if (!tx_info->inl) {
                        if ((void *) data >= end) {
                                data = ring->buf + ((void *)data - end);
                        }

                        if (tx_info->linear) {
                                dma_unmap_single(priv->ddev,
                                        (dma_addr_t) be64_to_cpu(data->addr),
                                         be32_to_cpu(data->byte_count),
                                         PCI_DMA_TODEVICE);
                                ++data;
                        }

                        for (i = 0; i < frags; i++) {
                                /* Check for wraparound before unmapping */
                                if ((void *) data >= end)
                                        data = ring->buf;
                                frag = &skb_shinfo(skb)->frags[i];
                                dma_unmap_page(priv->ddev,
                                        (dma_addr_t) be64_to_cpu(data->addr),
                                         skb_frag_size(frag), PCI_DMA_TODEVICE);
                                ++data;
                        }
                }
        }
        dev_kfree_skb_any(skb);
        return tx_info->nr_txbb;
}


int mlx4_en_free_tx_buf(struct net_device *dev, struct mlx4_en_tx_ring *ring)
{
        struct mlx4_en_priv *priv = netdev_priv(dev);
        int cnt = 0;

        /* Skip last polled descriptor */
        ring->cons += ring->last_nr_txbb;
        en_dbg(DRV, priv, "Freeing Tx buf - cons:0x%x prod:0x%x\n",
                 ring->cons, ring->prod);

        if ((u32) (ring->prod - ring->cons) > ring->size) {
                if (netif_msg_tx_err(priv))
                        en_warn(priv, "Tx consumer passed producer!\n");
                return 0;
        }

        while (ring->cons != ring->prod) {
                ring->last_nr_txbb = mlx4_en_free_tx_desc(priv, ring,
                                                ring->cons & ring->size_mask,
                                                !!(ring->cons & ring->size), 0);
                ring->cons += ring->last_nr_txbb;
                cnt++;
        }

        netdev_tx_reset_queue(ring->tx_queue);

        if (cnt)
                en_dbg(DRV, priv, "Freed %d uncompleted tx descriptors\n", cnt);

        return cnt;
}

static void mlx4_en_process_tx_cq(struct net_device *dev, struct mlx4_en_cq *cq)
{
        struct mlx4_en_priv *priv = netdev_priv(dev);
        struct mlx4_cq *mcq = &cq->mcq;
        struct mlx4_en_tx_ring *ring = priv->tx_ring[cq->ring];
        struct mlx4_cqe *cqe;
        u16 index;
        u16 new_index, ring_index, stamp_index;
        u32 txbbs_skipped = 0;
        u32 txbbs_stamp = 0;
        u32 cons_index = mcq->cons_index;
        int size = cq->size;
        u32 size_mask = ring->size_mask;
        struct mlx4_cqe *buf = cq->buf;
        u32 packets = 0;
        u32 bytes = 0;
        int factor = priv->cqe_factor;
        u64 timestamp = 0;

        if (!priv->port_up)
                return;

        index = cons_index & size_mask;
        cqe = &buf[(index << factor) + factor];
        ring_index = ring->cons & size_mask;
        stamp_index = ring_index;

        /* Process all completed CQEs */
        while (XNOR(cqe->owner_sr_opcode & MLX4_CQE_OWNER_MASK,
                        cons_index & size)) {
                /*
                 * make sure we read the CQE after we read the
                 * ownership bit
                 */
                rmb();

                if (unlikely((cqe->owner_sr_opcode & MLX4_CQE_OPCODE_MASK) ==
                             MLX4_CQE_OPCODE_ERROR)) {
                        struct mlx4_err_cqe *cqe_err = (struct mlx4_err_cqe *)cqe;

                        en_err(priv, "CQE error - vendor syndrome: 0x%x syndrome: 0x%x\n",
                               cqe_err->vendor_err_syndrome,
                               cqe_err->syndrome);
                }

                /* Skip over last polled CQE */
                new_index = be16_to_cpu(cqe->wqe_index) & size_mask;

                do {
                        txbbs_skipped += ring->last_nr_txbb;
                        ring_index = (ring_index + ring->last_nr_txbb) & size_mask;
                        if (ring->tx_info[ring_index].ts_requested)
                                timestamp = mlx4_en_get_cqe_ts(cqe);

                        /* free next descriptor */
                        ring->last_nr_txbb = mlx4_en_free_tx_desc(
                                        priv, ring, ring_index,
                                        !!((ring->cons + txbbs_skipped) &
                                        ring->size), timestamp);

                        mlx4_en_stamp_wqe(priv, ring, stamp_index,
                                          !!((ring->cons + txbbs_stamp) &
                                                ring->size));
                        stamp_index = ring_index;
                        txbbs_stamp = txbbs_skipped;
                        packets++;
                        bytes += ring->tx_info[ring_index].nr_bytes;
                } while (ring_index != new_index);

                ++cons_index;
                index = cons_index & size_mask;
                cqe = &buf[(index << factor) + factor];
        }


        /*
         * To prevent CQ overflow we first update CQ consumer and only then
         * the ring consumer.
         */
        mcq->cons_index = cons_index;
        mlx4_cq_set_ci(mcq);
        wmb();
        ring->cons += txbbs_skipped;
        netdev_tx_completed_queue(ring->tx_queue, packets, bytes);

        /*
         * Wakeup Tx queue if this stopped, and at least 1 packet
         * was completed
         */
        if (netif_tx_queue_stopped(ring->tx_queue) && txbbs_skipped > 0) {
                netif_tx_wake_queue(ring->tx_queue);
                priv->port_stats.wake_queue++;
        }
}

void mlx4_en_tx_irq(struct mlx4_cq *mcq)
{
        struct mlx4_en_cq *cq = container_of(mcq, struct mlx4_en_cq, mcq);
        struct mlx4_en_priv *priv = netdev_priv(cq->dev);

        mlx4_en_process_tx_cq(cq->dev, cq);
        mlx4_en_arm_cq(priv, cq);
}


static struct mlx4_en_tx_desc *mlx4_en_bounce_to_desc(struct mlx4_en_priv *priv,
                                                      struct mlx4_en_tx_ring *ring,
                                                      u32 index,
                                                      unsigned int desc_size)
{
        u32 copy = (ring->size - index) * TXBB_SIZE;
        int i;

        for (i = desc_size - copy - 4; i >= 0; i -= 4) {
                if ((i & (TXBB_SIZE - 1)) == 0)
                        wmb();

                *((u32 *) (ring->buf + i)) =
                        *((u32 *) (ring->bounce_buf + copy + i));
        }

        for (i = copy - 4; i >= 4 ; i -= 4) {
                if ((i & (TXBB_SIZE - 1)) == 0)
                        wmb();

                *((u32 *) (ring->buf + index * TXBB_SIZE + i)) =
                        *((u32 *) (ring->bounce_buf + i));
        }

        /* Return real descriptor location */
        return ring->buf + index * TXBB_SIZE;
}

static int is_inline(struct sk_buff *skb, void **pfrag)
{
        void *ptr;

        if (inline_thold && !skb_is_gso(skb) && skb->len <= inline_thold) {
                if (skb_shinfo(skb)->nr_frags == 1) {
                        ptr = skb_frag_address_safe(&skb_shinfo(skb)->frags[0]);
                        if (unlikely(!ptr))
                                return 0;

                        if (pfrag)
                                *pfrag = ptr;

                        return 1;
                } else if (unlikely(skb_shinfo(skb)->nr_frags))
                        return 0;
                else
                        return 1;
        }

        return 0;
}

static int inline_size(struct sk_buff *skb)
{
        if (skb->len + CTRL_SIZE + sizeof(struct mlx4_wqe_inline_seg)
            <= MLX4_INLINE_ALIGN)
                return ALIGN(skb->len + CTRL_SIZE +
                             sizeof(struct mlx4_wqe_inline_seg), 16);
        else
                return ALIGN(skb->len + CTRL_SIZE + 2 *
                             sizeof(struct mlx4_wqe_inline_seg), 16);
}

static int get_real_size(struct sk_buff *skb, struct net_device *dev,
                         int *lso_header_size)
{
        struct mlx4_en_priv *priv = netdev_priv(dev);
        int real_size;

        if (skb_is_gso(skb)) {
                *lso_header_size = skb_transport_offset(skb) + tcp_hdrlen(skb);
                real_size = CTRL_SIZE + skb_shinfo(skb)->nr_frags * DS_SIZE +
                        ALIGN(*lso_header_size + 4, DS_SIZE);
                if (unlikely(*lso_header_size != skb_headlen(skb))) {
                        /* We add a segment for the skb linear buffer only if
                         * it contains data */
                        if (*lso_header_size < skb_headlen(skb))
                                real_size += DS_SIZE;
                        else {
                                if (netif_msg_tx_err(priv))
                                        en_warn(priv, "Non-linear headers\n");
                                return 0;
                        }
                }
        } else {
                *lso_header_size = 0;
                if (!is_inline(skb, NULL))
                        real_size = CTRL_SIZE + (skb_shinfo(skb)->nr_frags + 1) * DS_SIZE;
                else
                        real_size = inline_size(skb);
        }

        return real_size;
}

static void build_inline_wqe(struct mlx4_en_tx_desc *tx_desc, struct sk_buff *skb,
                             int real_size, u16 *vlan_tag, int tx_ind, void *fragptr)
{
        struct mlx4_wqe_inline_seg *inl = &tx_desc->inl;
        int spc = MLX4_INLINE_ALIGN - CTRL_SIZE - sizeof *inl;

        if (skb->len <= spc) {
                inl->byte_count = cpu_to_be32(1 << 31 | skb->len);
                skb_copy_from_linear_data(skb, inl + 1, skb_headlen(skb));
                if (skb_shinfo(skb)->nr_frags)
                        memcpy(((void *)(inl + 1)) + skb_headlen(skb), fragptr,
                               skb_frag_size(&skb_shinfo(skb)->frags[0]));

        } else {
                inl->byte_count = cpu_to_be32(1 << 31 | spc);
                if (skb_headlen(skb) <= spc) {
                        skb_copy_from_linear_data(skb, inl + 1, skb_headlen(skb));
                        if (skb_headlen(skb) < spc) {
                                memcpy(((void *)(inl + 1)) + skb_headlen(skb),
                                        fragptr, spc - skb_headlen(skb));
                                fragptr +=  spc - skb_headlen(skb);
                        }
                        inl = (void *) (inl + 1) + spc;
                        memcpy(((void *)(inl + 1)), fragptr, skb->len - spc);
                } else {
                        skb_copy_from_linear_data(skb, inl + 1, spc);
                        inl = (void *) (inl + 1) + spc;
                        skb_copy_from_linear_data_offset(skb, spc, inl + 1,
                                        skb_headlen(skb) - spc);
                        if (skb_shinfo(skb)->nr_frags)
                                memcpy(((void *)(inl + 1)) + skb_headlen(skb) - spc,
                                        fragptr, skb_frag_size(&skb_shinfo(skb)->frags[0]));
                }

                wmb();
                inl->byte_count = cpu_to_be32(1 << 31 | (skb->len - spc));
        }
}

u16 mlx4_en_select_queue(struct net_device *dev, struct sk_buff *skb)
{
        struct mlx4_en_priv *priv = netdev_priv(dev);
        u16 rings_p_up = priv->num_tx_rings_p_up;
        u8 up = 0;

        if (dev->num_tc)
                return skb_tx_hash(dev, skb);

        if (vlan_tx_tag_present(skb))
                up = vlan_tx_tag_get(skb) >> VLAN_PRIO_SHIFT;

        return __netdev_pick_tx(dev, skb) % rings_p_up + up * rings_p_up;
}

static void mlx4_bf_copy(void __iomem *dst, unsigned long *src, unsigned bytecnt)
{
        __iowrite64_copy(dst, src, bytecnt / 8);
}

netdev_tx_t mlx4_en_xmit(struct sk_buff *skb, struct net_device *dev)
{
        struct mlx4_en_priv *priv = netdev_priv(dev);
        struct mlx4_en_dev *mdev = priv->mdev;
        struct device *ddev = priv->ddev;
        struct mlx4_en_tx_ring *ring;
        struct mlx4_en_tx_desc *tx_desc;
        struct mlx4_wqe_data_seg *data;
        struct mlx4_en_tx_info *tx_info;
        int tx_ind = 0;
        int nr_txbb;
        int desc_size;
        int real_size;
        u32 index, bf_index;
        __be32 op_own;
        u16 vlan_tag = 0;
        int i;
        int lso_header_size;
        void *fragptr;
        bool bounce = false;

        if (!priv->port_up)
                goto tx_drop;

        real_size = get_real_size(skb, dev, &lso_header_size);
        if (unlikely(!real_size))
                goto tx_drop;

        /* Align descriptor to TXBB size */
        desc_size = ALIGN(real_size, TXBB_SIZE);
        nr_txbb = desc_size / TXBB_SIZE;
        if (unlikely(nr_txbb > MAX_DESC_TXBBS)) {
                if (netif_msg_tx_err(priv))
                        en_warn(priv, "Oversized header or SG list\n");
                goto tx_drop;
        }

        tx_ind = skb->queue_mapping;
        ring = priv->tx_ring[tx_ind];
        if (vlan_tx_tag_present(skb))
                vlan_tag = vlan_tx_tag_get(skb);

        /* Check available TXBBs And 2K spare for prefetch */
        if (unlikely(((int)(ring->prod - ring->cons)) >
                     ring->size - HEADROOM - MAX_DESC_TXBBS)) {
                /* every full Tx ring stops queue */
                netif_tx_stop_queue(ring->tx_queue);
                priv->port_stats.queue_stopped++;

                /* If queue was emptied after the if, and before the
                 * stop_queue - need to wake the queue, or else it will remain
                 * stopped forever.
                 * Need a memory barrier to make sure ring->cons was not
                 * updated before queue was stopped.
                 */
                wmb();

                if (unlikely(((int)(ring->prod - ring->cons)) <=
                             ring->size - HEADROOM - MAX_DESC_TXBBS)) {
                        netif_tx_wake_queue(ring->tx_queue);
                        priv->port_stats.wake_queue++;
                } else {
                        return NETDEV_TX_BUSY;
                }
        }

        /* Track current inflight packets for performance analysis */
        AVG_PERF_COUNTER(priv->pstats.inflight_avg,
                         (u32) (ring->prod - ring->cons - 1));

        /* Packet is good - grab an index and transmit it */
        index = ring->prod & ring->size_mask;
        bf_index = ring->prod;

        /* See if we have enough space for whole descriptor TXBB for setting
         * SW ownership on next descriptor; if not, use a bounce buffer. */
        if (likely(index + nr_txbb <= ring->size))
                tx_desc = ring->buf + index * TXBB_SIZE;
        else {
                tx_desc = (struct mlx4_en_tx_desc *) ring->bounce_buf;
                bounce = true;
        }

        /* Save skb in tx_info ring */
        tx_info = &ring->tx_info[index];
        tx_info->skb = skb;
        tx_info->nr_txbb = nr_txbb;

        if (lso_header_size)
                data = ((void *)&tx_desc->lso + ALIGN(lso_header_size + 4,
                                                      DS_SIZE));
        else
                data = &tx_desc->data;

        /* valid only for none inline segments */
        tx_info->data_offset = (void *)data - (void *)tx_desc;

        tx_info->linear = (lso_header_size < skb_headlen(skb) &&
                           !is_inline(skb, NULL)) ? 1 : 0;

        data += skb_shinfo(skb)->nr_frags + tx_info->linear - 1;

        if (is_inline(skb, &fragptr)) {
                tx_info->inl = 1;
        } else {
                /* Map fragments */
                for (i = skb_shinfo(skb)->nr_frags - 1; i >= 0; i--) {
                        struct skb_frag_struct *frag;
                        dma_addr_t dma;

                        frag = &skb_shinfo(skb)->frags[i];
                        dma = skb_frag_dma_map(ddev, frag,
                                               0, skb_frag_size(frag),
                                               DMA_TO_DEVICE);
                        if (dma_mapping_error(ddev, dma))
                                goto tx_drop_unmap;

                        data->addr = cpu_to_be64(dma);
                        data->lkey = cpu_to_be32(mdev->mr.key);
                        wmb();
                        data->byte_count = cpu_to_be32(skb_frag_size(frag));
                        --data;
                }

                /* Map linear part */
                if (tx_info->linear) {
                        u32 byte_count = skb_headlen(skb) - lso_header_size;
                        dma_addr_t dma;

                        dma = dma_map_single(ddev, skb->data +
                                             lso_header_size, byte_count,
                                             PCI_DMA_TODEVICE);
                        if (dma_mapping_error(ddev, dma))
                                goto tx_drop_unmap;

                        data->addr = cpu_to_be64(dma);
                        data->lkey = cpu_to_be32(mdev->mr.key);
                        wmb();
                        data->byte_count = cpu_to_be32(byte_count);
                }
                tx_info->inl = 0;
        }

        /*
         * For timestamping add flag to skb_shinfo and
         * set flag for further reference
         */
        if (ring->hwtstamp_tx_type == HWTSTAMP_TX_ON &&
            skb_shinfo(skb)->tx_flags & SKBTX_HW_TSTAMP) {
                skb_shinfo(skb)->tx_flags |= SKBTX_IN_PROGRESS;
                tx_info->ts_requested = 1;
        }

        /* Prepare ctrl segement apart opcode+ownership, which depends on
         * whether LSO is used */
        tx_desc->ctrl.vlan_tag = cpu_to_be16(vlan_tag);
        tx_desc->ctrl.ins_vlan = MLX4_WQE_CTRL_INS_VLAN *
                !!vlan_tx_tag_present(skb);
        tx_desc->ctrl.fence_size = (real_size / 16) & 0x3f;
        tx_desc->ctrl.srcrb_flags = priv->ctrl_flags;
        if (likely(skb->ip_summed == CHECKSUM_PARTIAL)) {
                tx_desc->ctrl.srcrb_flags |= cpu_to_be32(MLX4_WQE_CTRL_IP_CSUM |
                                                         MLX4_WQE_CTRL_TCP_UDP_CSUM);
                ring->tx_csum++;
        }

        if (priv->flags & MLX4_EN_FLAG_ENABLE_HW_LOOPBACK) {
                struct ethhdr *ethh;

                /* Copy dst mac address to wqe. This allows loopback in eSwitch,
                 * so that VFs and PF can communicate with each other
                 */
                ethh = (struct ethhdr *)skb->data;
                tx_desc->ctrl.srcrb_flags16[0] = get_unaligned((__be16 *)ethh->h_dest);
                tx_desc->ctrl.imm = get_unaligned((__be32 *)(ethh->h_dest + 2));
        }

        /* Handle LSO (TSO) packets */
        if (lso_header_size) {
                /* Mark opcode as LSO */
                op_own = cpu_to_be32(MLX4_OPCODE_LSO | (1 << 6)) |
                        ((ring->prod & ring->size) ?
                                cpu_to_be32(MLX4_EN_BIT_DESC_OWN) : 0);

                /* Fill in the LSO prefix */
                tx_desc->lso.mss_hdr_size = cpu_to_be32(
                        skb_shinfo(skb)->gso_size << 16 | lso_header_size);

                /* Copy headers;
                 * note that we already verified that it is linear */
                memcpy(tx_desc->lso.header, skb->data, lso_header_size);

                priv->port_stats.tso_packets++;
                i = ((skb->len - lso_header_size) / skb_shinfo(skb)->gso_size) +
                        !!((skb->len - lso_header_size) % skb_shinfo(skb)->gso_size);
                tx_info->nr_bytes = skb->len + (i - 1) * lso_header_size;
                ring->packets += i;
        } else {
                /* Normal (Non LSO) packet */
                op_own = cpu_to_be32(MLX4_OPCODE_SEND) |
                        ((ring->prod & ring->size) ?
                         cpu_to_be32(MLX4_EN_BIT_DESC_OWN) : 0);
                tx_info->nr_bytes = max_t(unsigned int, skb->len, ETH_ZLEN);
                ring->packets++;

        }
        ring->bytes += tx_info->nr_bytes;
        netdev_tx_sent_queue(ring->tx_queue, tx_info->nr_bytes);
        AVG_PERF_COUNTER(priv->pstats.tx_pktsz_avg, skb->len);

        if (tx_info->inl) {
                build_inline_wqe(tx_desc, skb, real_size, &vlan_tag, tx_ind, fragptr);
                tx_info->inl = 1;
        }

        ring->prod += nr_txbb;

        /* If we used a bounce buffer then copy descriptor back into place */
        if (bounce)
                tx_desc = mlx4_en_bounce_to_desc(priv, ring, index, desc_size);

        skb_tx_timestamp(skb);

        if (ring->bf_enabled && desc_size <= MAX_BF && !bounce && !vlan_tx_tag_present(skb)) {
                *(__be32 *) (&tx_desc->ctrl.vlan_tag) |= cpu_to_be32(ring->doorbell_qpn);
                op_own |= htonl((bf_index & 0xffff) << 8);
                /* Ensure new descirptor hits memory
                * before setting ownership of this descriptor to HW */
                wmb();
                tx_desc->ctrl.owner_opcode = op_own;

                wmb();

                mlx4_bf_copy(ring->bf.reg + ring->bf.offset, (unsigned long *) &tx_desc->ctrl,
                     desc_size);

                wmb();

                ring->bf.offset ^= ring->bf.buf_size;
        } else {
                /* Ensure new descirptor hits memory
                * before setting ownership of this descriptor to HW */
                wmb();
                tx_desc->ctrl.owner_opcode = op_own;
                wmb();
                iowrite32be(ring->doorbell_qpn, ring->bf.uar->map + MLX4_SEND_DOORBELL);
        }

        return NETDEV_TX_OK;

tx_drop_unmap:
        en_err(priv, "DMA mapping error\n");

        for (i++; i < skb_shinfo(skb)->nr_frags; i++) {
                data++;
                dma_unmap_page(ddev, (dma_addr_t) be64_to_cpu(data->addr),
                               be32_to_cpu(data->byte_count),
                               PCI_DMA_TODEVICE);
        }

tx_drop:
        dev_kfree_skb_any(skb);
        priv->stats.tx_dropped++;
        return NETDEV_TX_OK;
}