/*
 * This file is part of the Chelsio T4 Ethernet driver for Linux.
 *
 * Copyright (c) 2003-2014 Chelsio Communications, Inc. 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 <linux/skbuff.h>
#include <linux/netdevice.h>
#include <linux/etherdevice.h>
#include <linux/if_vlan.h>
#include <linux/ip.h>
#include <linux/dma-mapping.h>
#include <linux/jiffies.h>
#include <linux/prefetch.h>
#include <linux/export.h>
#include <net/xfrm.h>
#include <net/ipv6.h>
#include <net/tcp.h>
#include <net/busy_poll.h>
#ifdef CONFIG_CHELSIO_T4_FCOE
#include <scsi/fc/fc_fcoe.h>
#endif /* CONFIG_CHELSIO_T4_FCOE */
#include "cxgb4.h"
#include "t4_regs.h"
#include "t4_values.h"
#include "t4_msg.h"
#include "t4fw_api.h"
#include "cxgb4_ptp.h"
#include "cxgb4_uld.h"

/*
 * Rx buffer size.  We use largish buffers if possible but settle for single
 * pages under memory shortage.
 */
#if PAGE_SHIFT >= 16
# define FL_PG_ORDER 0
#else
# define FL_PG_ORDER (16 - PAGE_SHIFT)
#endif

/* RX_PULL_LEN should be <= RX_COPY_THRES */
#define RX_COPY_THRES    256
#define RX_PULL_LEN      128

/*
 * Main body length for sk_buffs used for Rx Ethernet packets with fragments.
 * Should be >= RX_PULL_LEN but possibly bigger to give pskb_may_pull some room.
 */
#define RX_PKT_SKB_LEN   512

/*
 * Max number of Tx descriptors we clean up at a time.  Should be modest as
 * freeing skbs isn't cheap and it happens while holding locks.  We just need
 * to free packets faster than they arrive, we eventually catch up and keep
 * the amortized cost reasonable.  Must be >= 2 * TXQ_STOP_THRES.  It should
 * also match the CIDX Flush Threshold.
 */
#define MAX_TX_RECLAIM 32

/*
 * Max number of Rx buffers we replenish at a time.  Again keep this modest,
 * allocating buffers isn't cheap either.
 */
#define MAX_RX_REFILL 16U

/*
 * Period of the Rx queue check timer.  This timer is infrequent as it has
 * something to do only when the system experiences severe memory shortage.
 */
#define RX_QCHECK_PERIOD (HZ / 2)

/*
 * Period of the Tx queue check timer.
 */
#define TX_QCHECK_PERIOD (HZ / 2)

/*
 * Max number of Tx descriptors to be reclaimed by the Tx timer.
 */
#define MAX_TIMER_TX_RECLAIM 100

/*
 * Timer index used when backing off due to memory shortage.
 */
#define NOMEM_TMR_IDX (SGE_NTIMERS - 1)

/*
 * Suspension threshold for non-Ethernet Tx queues.  We require enough room
 * for a full sized WR.
 */
#define TXQ_STOP_THRES (SGE_MAX_WR_LEN / sizeof(struct tx_desc))

/*
 * Max Tx descriptor space we allow for an Ethernet packet to be inlined
 * into a WR.
 */
#define MAX_IMM_TX_PKT_LEN 256

/*
 * Max size of a WR sent through a control Tx queue.
 */
#define MAX_CTRL_WR_LEN SGE_MAX_WR_LEN

struct rx_sw_desc {                /* SW state per Rx descriptor */
        struct page *page;
        dma_addr_t dma_addr;
};

/*
 * Rx buffer sizes for "useskbs" Free List buffers (one ingress packet pe skb
 * buffer).  We currently only support two sizes for 1500- and 9000-byte MTUs.
 * We could easily support more but there doesn't seem to be much need for
 * that ...
 */
#define FL_MTU_SMALL 1500
#define FL_MTU_LARGE 9000

static inline unsigned int fl_mtu_bufsize(struct adapter *adapter,
                                          unsigned int mtu)
{
        struct sge *s = &adapter->sge;

        return ALIGN(s->pktshift + ETH_HLEN + VLAN_HLEN + mtu, s->fl_align);
}

#define FL_MTU_SMALL_BUFSIZE(adapter) fl_mtu_bufsize(adapter, FL_MTU_SMALL)
#define FL_MTU_LARGE_BUFSIZE(adapter) fl_mtu_bufsize(adapter, FL_MTU_LARGE)

/*
 * Bits 0..3 of rx_sw_desc.dma_addr have special meaning.  The hardware uses
 * these to specify the buffer size as an index into the SGE Free List Buffer
 * Size register array.  We also use bit 4, when the buffer has been unmapped
 * for DMA, but this is of course never sent to the hardware and is only used
 * to prevent double unmappings.  All of the above requires that the Free List
 * Buffers which we allocate have the bottom 5 bits free (0) -- i.e. are
 * 32-byte or or a power of 2 greater in alignment.  Since the SGE's minimal
 * Free List Buffer alignment is 32 bytes, this works out for us ...
 */
enum {
        RX_BUF_FLAGS     = 0x1f,   /* bottom five bits are special */
        RX_BUF_SIZE      = 0x0f,   /* bottom three bits are for buf sizes */
        RX_UNMAPPED_BUF  = 0x10,   /* buffer is not mapped */

        /*
         * XXX We shouldn't depend on being able to use these indices.
         * XXX Especially when some other Master PF has initialized the
         * XXX adapter or we use the Firmware Configuration File.  We
         * XXX should really search through the Host Buffer Size register
         * XXX array for the appropriately sized buffer indices.
         */
        RX_SMALL_PG_BUF  = 0x0,   /* small (PAGE_SIZE) page buffer */
        RX_LARGE_PG_BUF  = 0x1,   /* buffer large (FL_PG_ORDER) page buffer */

        RX_SMALL_MTU_BUF = 0x2,   /* small MTU buffer */
        RX_LARGE_MTU_BUF = 0x3,   /* large MTU buffer */
};

static int timer_pkt_quota[] = {1, 1, 2, 3, 4, 5};
#define MIN_NAPI_WORK  1

static inline dma_addr_t get_buf_addr(const struct rx_sw_desc *d)
{
        return d->dma_addr & ~(dma_addr_t)RX_BUF_FLAGS;
}

static inline bool is_buf_mapped(const struct rx_sw_desc *d)
{
        return !(d->dma_addr & RX_UNMAPPED_BUF);
}

/**
 *      txq_avail - return the number of available slots in a Tx queue
 *      @q: the Tx queue
 *
 *      Returns the number of descriptors in a Tx queue available to write new
 *      packets.
 */
static inline unsigned int txq_avail(const struct sge_txq *q)
{
        return q->size - 1 - q->in_use;
}

/**
 *      fl_cap - return the capacity of a free-buffer list
 *      @fl: the FL
 *
 *      Returns the capacity of a free-buffer list.  The capacity is less than
 *      the size because one descriptor needs to be left unpopulated, otherwise
 *      HW will think the FL is empty.
 */
static inline unsigned int fl_cap(const struct sge_fl *fl)
{
        return fl->size - 8;   /* 1 descriptor = 8 buffers */
}

/**
 *      fl_starving - return whether a Free List is starving.
 *      @adapter: pointer to the adapter
 *      @fl: the Free List
 *
 *      Tests specified Free List to see whether the number of buffers
 *      available to the hardware has falled below our "starvation"
 *      threshold.
 */
static inline bool fl_starving(const struct adapter *adapter,
                               const struct sge_fl *fl)
{
        const struct sge *s = &adapter->sge;

        return fl->avail - fl->pend_cred <= s->fl_starve_thres;
}

int cxgb4_map_skb(struct device *dev, const struct sk_buff *skb,
                  dma_addr_t *addr)
{
        const skb_frag_t *fp, *end;
        const struct skb_shared_info *si;

        *addr = dma_map_single(dev, skb->data, skb_headlen(skb), DMA_TO_DEVICE);
        if (dma_mapping_error(dev, *addr))
                goto out_err;

        si = skb_shinfo(skb);
        end = &si->frags[si->nr_frags];

        for (fp = si->frags; fp < end; fp++) {
                *++addr = skb_frag_dma_map(dev, fp, 0, skb_frag_size(fp),
                                           DMA_TO_DEVICE);
                if (dma_mapping_error(dev, *addr))
                        goto unwind;
        }
        return 0;

unwind:
        while (fp-- > si->frags)
                dma_unmap_page(dev, *--addr, skb_frag_size(fp), DMA_TO_DEVICE);

        dma_unmap_single(dev, addr[-1], skb_headlen(skb), DMA_TO_DEVICE);
out_err:
        return -ENOMEM;
}
EXPORT_SYMBOL(cxgb4_map_skb);

#ifdef CONFIG_NEED_DMA_MAP_STATE
static void unmap_skb(struct device *dev, const struct sk_buff *skb,
                      const dma_addr_t *addr)
{
        const skb_frag_t *fp, *end;
        const struct skb_shared_info *si;

        dma_unmap_single(dev, *addr++, skb_headlen(skb), DMA_TO_DEVICE);

        si = skb_shinfo(skb);
        end = &si->frags[si->nr_frags];
        for (fp = si->frags; fp < end; fp++)
                dma_unmap_page(dev, *addr++, skb_frag_size(fp), DMA_TO_DEVICE);
}

/**
 *      deferred_unmap_destructor - unmap a packet when it is freed
 *      @skb: the packet
 *
 *      This is the packet destructor used for Tx packets that need to remain
 *      mapped until they are freed rather than until their Tx descriptors are
 *      freed.
 */
static void deferred_unmap_destructor(struct sk_buff *skb)
{
        unmap_skb(skb->dev->dev.parent, skb, (dma_addr_t *)skb->head);
}
#endif

static void unmap_sgl(struct device *dev, const struct sk_buff *skb,
                      const struct ulptx_sgl *sgl, const struct sge_txq *q)
{
        const struct ulptx_sge_pair *p;
        unsigned int nfrags = skb_shinfo(skb)->nr_frags;

        if (likely(skb_headlen(skb)))
                dma_unmap_single(dev, be64_to_cpu(sgl->addr0), ntohl(sgl->len0),
                                 DMA_TO_DEVICE);
        else {
                dma_unmap_page(dev, be64_to_cpu(sgl->addr0), ntohl(sgl->len0),
                               DMA_TO_DEVICE);
                nfrags--;
        }

        /*
         * the complexity below is because of the possibility of a wrap-around
         * in the middle of an SGL
         */
        for (p = sgl->sge; nfrags >= 2; nfrags -= 2) {
                if (likely((u8 *)(p + 1) <= (u8 *)q->stat)) {
unmap:                  dma_unmap_page(dev, be64_to_cpu(p->addr[0]),
                                       ntohl(p->len[0]), DMA_TO_DEVICE);
                        dma_unmap_page(dev, be64_to_cpu(p->addr[1]),
                                       ntohl(p->len[1]), DMA_TO_DEVICE);
                        p++;
                } else if ((u8 *)p == (u8 *)q->stat) {
                        p = (const struct ulptx_sge_pair *)q->desc;
                        goto unmap;
                } else if ((u8 *)p + 8 == (u8 *)q->stat) {
                        const __be64 *addr = (const __be64 *)q->desc;

                        dma_unmap_page(dev, be64_to_cpu(addr[0]),
                                       ntohl(p->len[0]), DMA_TO_DEVICE);
                        dma_unmap_page(dev, be64_to_cpu(addr[1]),
                                       ntohl(p->len[1]), DMA_TO_DEVICE);
                        p = (const struct ulptx_sge_pair *)&addr[2];
                } else {
                        const __be64 *addr = (const __be64 *)q->desc;

                        dma_unmap_page(dev, be64_to_cpu(p->addr[0]),
                                       ntohl(p->len[0]), DMA_TO_DEVICE);
                        dma_unmap_page(dev, be64_to_cpu(addr[0]),
                                       ntohl(p->len[1]), DMA_TO_DEVICE);
                        p = (const struct ulptx_sge_pair *)&addr[1];
                }
        }
        if (nfrags) {
                __be64 addr;

                if ((u8 *)p == (u8 *)q->stat)
                        p = (const struct ulptx_sge_pair *)q->desc;
                addr = (u8 *)p + 16 <= (u8 *)q->stat ? p->addr[0] :
                                                       *(const __be64 *)q->desc;
                dma_unmap_page(dev, be64_to_cpu(addr), ntohl(p->len[0]),
                               DMA_TO_DEVICE);
        }
}

/**
 *      free_tx_desc - reclaims Tx descriptors and their buffers
 *      @adapter: the adapter
 *      @q: the Tx queue to reclaim descriptors from
 *      @n: the number of descriptors to reclaim
 *      @unmap: whether the buffers should be unmapped for DMA
 *
 *      Reclaims Tx descriptors from an SGE Tx queue and frees the associated
 *      Tx buffers.  Called with the Tx queue lock held.
 */
void free_tx_desc(struct adapter *adap, struct sge_txq *q,
                  unsigned int n, bool unmap)
{
        struct tx_sw_desc *d;
        unsigned int cidx = q->cidx;
        struct device *dev = adap->pdev_dev;

        d = &q->sdesc[cidx];
        while (n--) {
                if (d->skb) {                       /* an SGL is present */
                        if (unmap)
                                unmap_sgl(dev, d->skb, d->sgl, q);
                        dev_consume_skb_any(d->skb);
                        d->skb = NULL;
                }
                ++d;
                if (++cidx == q->size) {
                        cidx = 0;
                        d = q->sdesc;
                }
        }
        q->cidx = cidx;
}

/*
 * Return the number of reclaimable descriptors in a Tx queue.
 */
static inline int reclaimable(const struct sge_txq *q)
{
        int hw_cidx = ntohs(READ_ONCE(q->stat->cidx));
        hw_cidx -= q->cidx;
        return hw_cidx < 0 ? hw_cidx + q->size : hw_cidx;
}

/**
 *      reclaim_completed_tx - reclaims completed TX Descriptors
 *      @adap: the adapter
 *      @q: the Tx queue to reclaim completed descriptors from
 *      @maxreclaim: the maximum number of TX Descriptors to reclaim or -1
 *      @unmap: whether the buffers should be unmapped for DMA
 *
 *      Reclaims Tx Descriptors that the SGE has indicated it has processed,
 *      and frees the associated buffers if possible.  If @max == -1, then
 *      we'll use a defaiult maximum.  Called with the TX Queue locked.
 */
static inline int reclaim_completed_tx(struct adapter *adap, struct sge_txq *q,
                                       int maxreclaim, bool unmap)
{
        int reclaim = reclaimable(q);

        if (reclaim) {
                /*
                 * Limit the amount of clean up work we do at a time to keep
                 * the Tx lock hold time O(1).
                 */
                if (maxreclaim < 0)
                        maxreclaim = MAX_TX_RECLAIM;
                if (reclaim > maxreclaim)
                        reclaim = maxreclaim;

                free_tx_desc(adap, q, reclaim, unmap);
                q->in_use -= reclaim;
        }

        return reclaim;
}

/**
 *      cxgb4_reclaim_completed_tx - reclaims completed Tx descriptors
 *      @adap: the adapter
 *      @q: the Tx queue to reclaim completed descriptors from
 *      @unmap: whether the buffers should be unmapped for DMA
 *
 *      Reclaims Tx descriptors that the SGE has indicated it has processed,
 *      and frees the associated buffers if possible.  Called with the Tx
 *      queue locked.
 */
void cxgb4_reclaim_completed_tx(struct adapter *adap, struct sge_txq *q,
                                bool unmap)
{
        (void)reclaim_completed_tx(adap, q, -1, unmap);
}
EXPORT_SYMBOL(cxgb4_reclaim_completed_tx);

static inline int get_buf_size(struct adapter *adapter,
                               const struct rx_sw_desc *d)
{
        struct sge *s = &adapter->sge;
        unsigned int rx_buf_size_idx = d->dma_addr & RX_BUF_SIZE;
        int buf_size;

        switch (rx_buf_size_idx) {
        case RX_SMALL_PG_BUF:
                buf_size = PAGE_SIZE;
                break;

        case RX_LARGE_PG_BUF:
                buf_size = PAGE_SIZE << s->fl_pg_order;
                break;

        case RX_SMALL_MTU_BUF:
                buf_size = FL_MTU_SMALL_BUFSIZE(adapter);
                break;

        case RX_LARGE_MTU_BUF:
                buf_size = FL_MTU_LARGE_BUFSIZE(adapter);
                break;

        default:
                BUG();
        }

        return buf_size;
}

/**
 *      free_rx_bufs - free the Rx buffers on an SGE free list
 *      @adap: the adapter
 *      @q: the SGE free list to free buffers from
 *      @n: how many buffers to free
 *
 *      Release the next @n buffers on an SGE free-buffer Rx queue.   The
 *      buffers must be made inaccessible to HW before calling this function.
 */
static void free_rx_bufs(struct adapter *adap, struct sge_fl *q, int n)
{
        while (n--) {
                struct rx_sw_desc *d = &q->sdesc[q->cidx];

                if (is_buf_mapped(d))
                        dma_unmap_page(adap->pdev_dev, get_buf_addr(d),
                                       get_buf_size(adap, d),
                                       PCI_DMA_FROMDEVICE);
                put_page(d->page);
                d->page = NULL;
                if (++q->cidx == q->size)
                        q->cidx = 0;
                q->avail--;
        }
}

/**
 *      unmap_rx_buf - unmap the current Rx buffer on an SGE free list
 *      @adap: the adapter
 *      @q: the SGE free list
 *
 *      Unmap the current buffer on an SGE free-buffer Rx queue.   The
 *      buffer must be made inaccessible to HW before calling this function.
 *
 *      This is similar to @free_rx_bufs above but does not free the buffer.
 *      Do note that the FL still loses any further access to the buffer.
 */
static void unmap_rx_buf(struct adapter *adap, struct sge_fl *q)
{
        struct rx_sw_desc *d = &q->sdesc[q->cidx];

        if (is_buf_mapped(d))
                dma_unmap_page(adap->pdev_dev, get_buf_addr(d),
                               get_buf_size(adap, d), PCI_DMA_FROMDEVICE);
        d->page = NULL;
        if (++q->cidx == q->size)
                q->cidx = 0;
        q->avail--;
}

static inline void ring_fl_db(struct adapter *adap, struct sge_fl *q)
{
        if (q->pend_cred >= 8) {
                u32 val = adap->params.arch.sge_fl_db;

                if (is_t4(adap->params.chip))
                        val |= PIDX_V(q->pend_cred / 8);
                else
                        val |= PIDX_T5_V(q->pend_cred / 8);

                /* Make sure all memory writes to the Free List queue are
                 * committed before we tell the hardware about them.
                 */
                wmb();

                /* If we don't have access to the new User Doorbell (T5+), use
                 * the old doorbell mechanism; otherwise use the new BAR2
                 * mechanism.
                 */
                if (unlikely(q->bar2_addr == NULL)) {
                        t4_write_reg(adap, MYPF_REG(SGE_PF_KDOORBELL_A),
                                     val | QID_V(q->cntxt_id));
                } else {
                        writel(val | QID_V(q->bar2_qid),
                               q->bar2_addr + SGE_UDB_KDOORBELL);

                        /* This Write memory Barrier will force the write to
                         * the User Doorbell area to be flushed.
                         */
                        wmb();
                }
                q->pend_cred &= 7;
        }
}

static inline void set_rx_sw_desc(struct rx_sw_desc *sd, struct page *pg,
                                  dma_addr_t mapping)
{
        sd->page = pg;
        sd->dma_addr = mapping;      /* includes size low bits */
}

/**
 *      refill_fl - refill an SGE Rx buffer ring
 *      @adap: the adapter
 *      @q: the ring to refill
 *      @n: the number of new buffers to allocate
 *      @gfp: the gfp flags for the allocations
 *
 *      (Re)populate an SGE free-buffer queue with up to @n new packet buffers,
 *      allocated with the supplied gfp flags.  The caller must assure that
 *      @n does not exceed the queue's capacity.  If afterwards the queue is
 *      found critically low mark it as starving in the bitmap of starving FLs.
 *
 *      Returns the number of buffers allocated.
 */
static unsigned int refill_fl(struct adapter *adap, struct sge_fl *q, int n,
                              gfp_t gfp)
{
        struct sge *s = &adap->sge;
        struct page *pg;
        dma_addr_t mapping;
        unsigned int cred = q->avail;
        __be64 *d = &q->desc[q->pidx];
        struct rx_sw_desc *sd = &q->sdesc[q->pidx];
        int node;

#ifdef CONFIG_DEBUG_FS
        if (test_bit(q->cntxt_id - adap->sge.egr_start, adap->sge.blocked_fl))
                goto out;
#endif

        gfp |= __GFP_NOWARN;
        node = dev_to_node(adap->pdev_dev);

        if (s->fl_pg_order == 0)
                goto alloc_small_pages;

        /*
         * Prefer large buffers
         */
        while (n) {
                pg = alloc_pages_node(node, gfp | __GFP_COMP, s->fl_pg_order);
                if (unlikely(!pg)) {
                        q->large_alloc_failed++;
                        break;       /* fall back to single pages */
                }

                mapping = dma_map_page(adap->pdev_dev, pg, 0,
                                       PAGE_SIZE << s->fl_pg_order,
                                       PCI_DMA_FROMDEVICE);
                if (unlikely(dma_mapping_error(adap->pdev_dev, mapping))) {
                        __free_pages(pg, s->fl_pg_order);
                        q->mapping_err++;
                        goto out;   /* do not try small pages for this error */
                }
                mapping |= RX_LARGE_PG_BUF;
                *d++ = cpu_to_be64(mapping);

                set_rx_sw_desc(sd, pg, mapping);
                sd++;

                q->avail++;
                if (++q->pidx == q->size) {
                        q->pidx = 0;
                        sd = q->sdesc;
                        d = q->desc;
                }
                n--;
        }

alloc_small_pages:
        while (n--) {
                pg = alloc_pages_node(node, gfp, 0);
                if (unlikely(!pg)) {
                        q->alloc_failed++;
                        break;
                }

                mapping = dma_map_page(adap->pdev_dev, pg, 0, PAGE_SIZE,
                                       PCI_DMA_FROMDEVICE);
                if (unlikely(dma_mapping_error(adap->pdev_dev, mapping))) {
                        put_page(pg);
                        q->mapping_err++;
                        goto out;
                }
                *d++ = cpu_to_be64(mapping);

                set_rx_sw_desc(sd, pg, mapping);
                sd++;

                q->avail++;
                if (++q->pidx == q->size) {
                        q->pidx = 0;
                        sd = q->sdesc;
                        d = q->desc;
                }
        }

out:    cred = q->avail - cred;
        q->pend_cred += cred;
        ring_fl_db(adap, q);

        if (unlikely(fl_starving(adap, q))) {
                smp_wmb();
                q->low++;
                set_bit(q->cntxt_id - adap->sge.egr_start,
                        adap->sge.starving_fl);
        }

        return cred;
}

static inline void __refill_fl(struct adapter *adap, struct sge_fl *fl)
{
        refill_fl(adap, fl, min(MAX_RX_REFILL, fl_cap(fl) - fl->avail),
                  GFP_ATOMIC);
}

/**
 *      alloc_ring - allocate resources for an SGE descriptor ring
 *      @dev: the PCI device's core device
 *      @nelem: the number of descriptors
 *      @elem_size: the size of each descriptor
 *      @sw_size: the size of the SW state associated with each ring element
 *      @phys: the physical address of the allocated ring
 *      @metadata: address of the array holding the SW state for the ring
 *      @stat_size: extra space in HW ring for status information
 *      @node: preferred node for memory allocations
 *
 *      Allocates resources for an SGE descriptor ring, such as Tx queues,
 *      free buffer lists, or response queues.  Each SGE ring requires
 *      space for its HW descriptors plus, optionally, space for the SW state
 *      associated with each HW entry (the metadata).  The function returns
 *      three values: the virtual address for the HW ring (the return value
 *      of the function), the bus address of the HW ring, and the address
 *      of the SW ring.
 */
static void *alloc_ring(struct device *dev, size_t nelem, size_t elem_size,
                        size_t sw_size, dma_addr_t *phys, void *metadata,
                        size_t stat_size, int node)
{
        size_t len = nelem * elem_size + stat_size;
        void *s = NULL;
        void *p = dma_alloc_coherent(dev, len, phys, GFP_KERNEL);

        if (!p)
                return NULL;
        if (sw_size) {
                s = kcalloc_node(sw_size, nelem, GFP_KERNEL, node);

                if (!s) {
                        dma_free_coherent(dev, len, p, *phys);
                        return NULL;
                }
        }
        if (metadata)
                *(void **)metadata = s;
        return p;
}

/**
 *      sgl_len - calculates the size of an SGL of the given capacity
 *      @n: the number of SGL entries
 *
 *      Calculates the number of flits needed for a scatter/gather list that
 *      can hold the given number of entries.
 */
static inline unsigned int sgl_len(unsigned int n)
{
        /* A Direct Scatter Gather List uses 32-bit lengths and 64-bit PCI DMA
         * addresses.  The DSGL Work Request starts off with a 32-bit DSGL
         * ULPTX header, then Length0, then Address0, then, for 1 <= i <= N,
         * repeated sequences of { Length[i], Length[i+1], Address[i],
         * Address[i+1] } (this ensures that all addresses are on 64-bit
         * boundaries).  If N is even, then Length[N+1] should be set to 0 and
         * Address[N+1] is omitted.
         *
         * The following calculation incorporates all of the above.  It's
         * somewhat hard to follow but, briefly: the "+2" accounts for the
         * first two flits which include the DSGL header, Length0 and
         * Address0; the "(3*(n-1))/2" covers the main body of list entries (3
         * flits for every pair of the remaining N) +1 if (n-1) is odd; and
         * finally the "+((n-1)&1)" adds the one remaining flit needed if
         * (n-1) is odd ...
         */
        n--;
        return (3 * n) / 2 + (n & 1) + 2;
}

/**
 *      flits_to_desc - returns the num of Tx descriptors for the given flits
 *      @n: the number of flits
 *
 *      Returns the number of Tx descriptors needed for the supplied number
 *      of flits.
 */
static inline unsigned int flits_to_desc(unsigned int n)
{
        BUG_ON(n > SGE_MAX_WR_LEN / 8);
        return DIV_ROUND_UP(n, 8);
}

/**
 *      is_eth_imm - can an Ethernet packet be sent as immediate data?
 *      @skb: the packet
 *
 *      Returns whether an Ethernet packet is small enough to fit as
 *      immediate data. Return value corresponds to headroom required.
 */
static inline int is_eth_imm(const struct sk_buff *skb, unsigned int chip_ver)
{
        int hdrlen = 0;

        if (skb->encapsulation && skb_shinfo(skb)->gso_size &&
            chip_ver > CHELSIO_T5) {
                hdrlen = sizeof(struct cpl_tx_tnl_lso);
                hdrlen += sizeof(struct cpl_tx_pkt_core);
        } else {
                hdrlen = skb_shinfo(skb)->gso_size ?
                         sizeof(struct cpl_tx_pkt_lso_core) : 0;
                hdrlen += sizeof(struct cpl_tx_pkt);
        }
        if (skb->len <= MAX_IMM_TX_PKT_LEN - hdrlen)
                return hdrlen;
        return 0;
}

/**
 *      calc_tx_flits - calculate the number of flits for a packet Tx WR
 *      @skb: the packet
 *
 *      Returns the number of flits needed for a Tx WR for the given Ethernet
 *      packet, including the needed WR and CPL headers.
 */
static inline unsigned int calc_tx_flits(const struct sk_buff *skb,
                                         unsigned int chip_ver)
{
        unsigned int flits;
        int hdrlen = is_eth_imm(skb, chip_ver);

        /* If the skb is small enough, we can pump it out as a work request
         * with only immediate data.  In that case we just have to have the
         * TX Packet header plus the skb data in the Work Request.
         */

        if (hdrlen)
                return DIV_ROUND_UP(skb->len + hdrlen, sizeof(__be64));

        /* Otherwise, we're going to have to construct a Scatter gather list
         * of the skb body and fragments.  We also include the flits necessary
         * for the TX Packet Work Request and CPL.  We always have a firmware
         * Write Header (incorporated as part of the cpl_tx_pkt_lso and
         * cpl_tx_pkt structures), followed by either a TX Packet Write CPL
         * message or, if we're doing a Large Send Offload, an LSO CPL message
         * with an embedded TX Packet Write CPL message.
         */
        flits = sgl_len(skb_shinfo(skb)->nr_frags + 1);
        if (skb_shinfo(skb)->gso_size) {
                if (skb->encapsulation && chip_ver > CHELSIO_T5)
                        hdrlen = sizeof(struct fw_eth_tx_pkt_wr) +
                                 sizeof(struct cpl_tx_tnl_lso);
                else
                        hdrlen = sizeof(struct fw_eth_tx_pkt_wr) +
                                 sizeof(struct cpl_tx_pkt_lso_core);

                hdrlen += sizeof(struct cpl_tx_pkt_core);
                flits += (hdrlen / sizeof(__be64));
        } else {
                flits += (sizeof(struct fw_eth_tx_pkt_wr) +
                          sizeof(struct cpl_tx_pkt_core)) / sizeof(__be64);
        }
        return flits;
}

/**
 *      calc_tx_descs - calculate the number of Tx descriptors for a packet
 *      @skb: the packet
 *
 *      Returns the number of Tx descriptors needed for the given Ethernet
 *      packet, including the needed WR and CPL headers.
 */
static inline unsigned int calc_tx_descs(const struct sk_buff *skb,
                                         unsigned int chip_ver)
{
        return flits_to_desc(calc_tx_flits(skb, chip_ver));
}

/**
 *      cxgb4_write_sgl - populate a scatter/gather list for a packet
 *      @skb: the packet
 *      @q: the Tx queue we are writing into
 *      @sgl: starting location for writing the SGL
 *      @end: points right after the end of the SGL
 *      @start: start offset into skb main-body data to include in the SGL
 *      @addr: the list of bus addresses for the SGL elements
 *
 *      Generates a gather list for the buffers that make up a packet.
 *      The caller must provide adequate space for the SGL that will be written.
 *      The SGL includes all of the packet's page fragments and the data in its
 *      main body except for the first @start bytes.  @sgl must be 16-byte
 *      aligned and within a Tx descriptor with available space.  @end points
 *      right after the end of the SGL but does not account for any potential
 *      wrap around, i.e., @end > @sgl.
 */
void cxgb4_write_sgl(const struct sk_buff *skb, struct sge_txq *q,
                     struct ulptx_sgl *sgl, u64 *end, unsigned int start,
                     const dma_addr_t *addr)
{
        unsigned int i, len;
        struct ulptx_sge_pair *to;
        const struct skb_shared_info *si = skb_shinfo(skb);
        unsigned int nfrags = si->nr_frags;
        struct ulptx_sge_pair buf[MAX_SKB_FRAGS / 2 + 1];

        len = skb_headlen(skb) - start;
        if (likely(len)) {
                sgl->len0 = htonl(len);
                sgl->addr0 = cpu_to_be64(addr[0] + start);
                nfrags++;
        } else {
                sgl->len0 = htonl(skb_frag_size(&si->frags[0]));
                sgl->addr0 = cpu_to_be64(addr[1]);
        }

        sgl->cmd_nsge = htonl(ULPTX_CMD_V(ULP_TX_SC_DSGL) |
                              ULPTX_NSGE_V(nfrags));
        if (likely(--nfrags == 0))
                return;
        /*
         * Most of the complexity below deals with the possibility we hit the
         * end of the queue in the middle of writing the SGL.  For this case
         * only we create the SGL in a temporary buffer and then copy it.
         */
        to = (u8 *)end > (u8 *)q->stat ? buf : sgl->sge;

        for (i = (nfrags != si->nr_frags); nfrags >= 2; nfrags -= 2, to++) {
                to->len[0] = cpu_to_be32(skb_frag_size(&si->frags[i]));
                to->len[1] = cpu_to_be32(skb_frag_size(&si->frags[++i]));
                to->addr[0] = cpu_to_be64(addr[i]);
                to->addr[1] = cpu_to_be64(addr[++i]);
        }
        if (nfrags) {
                to->len[0] = cpu_to_be32(skb_frag_size(&si->frags[i]));
                to->len[1] = cpu_to_be32(0);
                to->addr[0] = cpu_to_be64(addr[i + 1]);
        }
        if (unlikely((u8 *)end > (u8 *)q->stat)) {
                unsigned int part0 = (u8 *)q->stat - (u8 *)sgl->sge, part1;

                if (likely(part0))
                        memcpy(sgl->sge, buf, part0);
                part1 = (u8 *)end - (u8 *)q->stat;
                memcpy(q->desc, (u8 *)buf + part0, part1);
                end = (void *)q->desc + part1;
        }
        if ((uintptr_t)end & 8)           /* 0-pad to multiple of 16 */
                *end = 0;
}
EXPORT_SYMBOL(cxgb4_write_sgl);

/* This function copies 64 byte coalesced work request to
 * memory mapped BAR2 space. For coalesced WR SGE fetches
 * data from the FIFO instead of from Host.
 */
static void cxgb_pio_copy(u64 __iomem *dst, u64 *src)
{
        int count = 8;

        while (count) {
                writeq(*src, dst);
                src++;
                dst++;
                count--;
        }
}

/**
 *      cxgb4_ring_tx_db - check and potentially ring a Tx queue's doorbell
 *      @adap: the adapter
 *      @q: the Tx queue
 *      @n: number of new descriptors to give to HW
 *
 *      Ring the doorbel for a Tx queue.
 */
inline void cxgb4_ring_tx_db(struct adapter *adap, struct sge_txq *q, int n)
{
        /* Make sure that all writes to the TX Descriptors are committed
         * before we tell the hardware about them.
         */
        wmb();

        /* If we don't have access to the new User Doorbell (T5+), use the old
         * doorbell mechanism; otherwise use the new BAR2 mechanism.
         */
        if (unlikely(q->bar2_addr == NULL)) {
                u32 val = PIDX_V(n);
                unsigned long flags;

                /* For T4 we need to participate in the Doorbell Recovery
                 * mechanism.
                 */
                spin_lock_irqsave(&q->db_lock, flags);
                if (!q->db_disabled)
                        t4_write_reg(adap, MYPF_REG(SGE_PF_KDOORBELL_A),
                                     QID_V(q->cntxt_id) | val);
                else
                        q->db_pidx_inc += n;
                q->db_pidx = q->pidx;
                spin_unlock_irqrestore(&q->db_lock, flags);
        } else {
                u32 val = PIDX_T5_V(n);

                /* T4 and later chips share the same PIDX field offset within
                 * the doorbell, but T5 and later shrank the field in order to
                 * gain a bit for Doorbell Priority.  The field was absurdly
                 * large in the first place (14 bits) so we just use the T5
                 * and later limits and warn if a Queue ID is too large.
                 */
                WARN_ON(val & DBPRIO_F);

                /* If we're only writing a single TX Descriptor and we can use
                 * Inferred QID registers, we can use the Write Combining
                 * Gather Buffer; otherwise we use the simple doorbell.
                 */
                if (n == 1 && q->bar2_qid == 0) {

                        int index = (q->pidx
                                     ? (q->pidx - 1)
                                     : (q->size - 1));
                        u64 *wr = (u64 *)&q->desc[index];

                        cxgb_pio_copy((u64 __iomem *)
                                      (q->bar2_addr + SGE_UDB_WCDOORBELL),
                                      wr);
                } else {
                        writel(val | QID_V(q->bar2_qid),
                               q->bar2_addr + SGE_UDB_KDOORBELL);
                }

                /* This Write Memory Barrier will force the write to the User
                 * Doorbell area to be flushed.  This is needed to prevent
                 * writes on different CPUs for the same queue from hitting
                 * the adapter out of order.  This is required when some Work
                 * Requests take the Write Combine Gather Buffer path (user
                 * doorbell area offset [SGE_UDB_WCDOORBELL..+63]) and some
                 * take the traditional path where we simply increment the
                 * PIDX (User Doorbell area SGE_UDB_KDOORBELL) and have the
                 * hardware DMA read the actual Work Request.
                 */
                wmb();
        }
}
EXPORT_SYMBOL(cxgb4_ring_tx_db);

/**
 *      cxgb4_inline_tx_skb - inline a packet's data into Tx descriptors
 *      @skb: the packet
 *      @q: the Tx queue where the packet will be inlined
 *      @pos: starting position in the Tx queue where to inline the packet
 *
 *      Inline a packet's contents directly into Tx descriptors, starting at
 *      the given position within the Tx DMA ring.
 *      Most of the complexity of this operation is dealing with wrap arounds
 *      in the middle of the packet we want to inline.
 */
void cxgb4_inline_tx_skb(const struct sk_buff *skb,
                         const struct sge_txq *q, void *pos)
{
        int left = (void *)q->stat - pos;
        u64 *p;

        if (likely(skb->len <= left)) {
                if (likely(!skb->data_len))
                        skb_copy_from_linear_data(skb, pos, skb->len);
                else
                        skb_copy_bits(skb, 0, pos, skb->len);
                pos += skb->len;
        } else {
                skb_copy_bits(skb, 0, pos, left);
                skb_copy_bits(skb, left, q->desc, skb->len - left);
                pos = (void *)q->desc + (skb->len - left);
        }

        /* 0-pad to multiple of 16 */
        p = PTR_ALIGN(pos, 8);
        if ((uintptr_t)p & 8)
                *p = 0;
}
EXPORT_SYMBOL(cxgb4_inline_tx_skb);

static void *inline_tx_skb_header(const struct sk_buff *skb,
                                  const struct sge_txq *q,  void *pos,
                                  int length)
{
        u64 *p;
        int left = (void *)q->stat - pos;

        if (likely(length <= left)) {
                memcpy(pos, skb->data, length);
                pos += length;
        } else {
                memcpy(pos, skb->data, left);
                memcpy(q->desc, skb->data + left, length - left);
                pos = (void *)q->desc + (length - left);
        }
        /* 0-pad to multiple of 16 */
        p = PTR_ALIGN(pos, 8);
        if ((uintptr_t)p & 8) {
                *p = 0;
                return p + 1;
        }
        return p;
}

/*
 * Figure out what HW csum a packet wants and return the appropriate control
 * bits.
 */
static u64 hwcsum(enum chip_type chip, const struct sk_buff *skb)
{
        int csum_type;
        bool inner_hdr_csum = false;
        u16 proto, ver;

        if (skb->encapsulation &&
            (CHELSIO_CHIP_VERSION(chip) > CHELSIO_T5))
                inner_hdr_csum = true;

        if (inner_hdr_csum) {
                ver = inner_ip_hdr(skb)->version;
                proto = (ver == 4) ? inner_ip_hdr(skb)->protocol :
                        inner_ipv6_hdr(skb)->nexthdr;
        } else {
                ver = ip_hdr(skb)->version;
                proto = (ver == 4) ? ip_hdr(skb)->protocol :
                        ipv6_hdr(skb)->nexthdr;
        }

        if (ver == 4) {
                if (proto == IPPROTO_TCP)
                        csum_type = TX_CSUM_TCPIP;
                else if (proto == IPPROTO_UDP)
                        csum_type = TX_CSUM_UDPIP;
                else {
nocsum:                 /*
                         * unknown protocol, disable HW csum
                         * and hope a bad packet is detected
                         */
                        return TXPKT_L4CSUM_DIS_F;
                }
        } else {
                /*
                 * this doesn't work with extension headers
                 */
                if (proto == IPPROTO_TCP)
                        csum_type = TX_CSUM_TCPIP6;
                else if (proto == IPPROTO_UDP)
                        csum_type = TX_CSUM_UDPIP6;
                else
                        goto nocsum;
        }

        if (likely(csum_type >= TX_CSUM_TCPIP)) {
                int eth_hdr_len, l4_len;
                u64 hdr_len;

                if (inner_hdr_csum) {
                        /* This allows checksum offload for all encapsulated
                         * packets like GRE etc..
                         */
                        l4_len = skb_inner_network_header_len(skb);
                        eth_hdr_len = skb_inner_network_offset(skb) - ETH_HLEN;
                } else {
                        l4_len = skb_network_header_len(skb);
                        eth_hdr_len = skb_network_offset(skb) - ETH_HLEN;
                }
                hdr_len = TXPKT_IPHDR_LEN_V(l4_len);

                if (CHELSIO_CHIP_VERSION(chip) <= CHELSIO_T5)
                        hdr_len |= TXPKT_ETHHDR_LEN_V(eth_hdr_len);
                else
                        hdr_len |= T6_TXPKT_ETHHDR_LEN_V(eth_hdr_len);
                return TXPKT_CSUM_TYPE_V(csum_type) | hdr_len;
        } else {
                int start = skb_transport_offset(skb);

                return TXPKT_CSUM_TYPE_V(csum_type) |
                        TXPKT_CSUM_START_V(start) |
                        TXPKT_CSUM_LOC_V(start + skb->csum_offset);
        }
}

static void eth_txq_stop(struct sge_eth_txq *q)
{
        netif_tx_stop_queue(q->txq);
        q->q.stops++;
}

static inline void txq_advance(struct sge_txq *q, unsigned int n)
{
        q->in_use += n;
        q->pidx += n;
        if (q->pidx >= q->size)
                q->pidx -= q->size;
}

#ifdef CONFIG_CHELSIO_T4_FCOE
static inline int
cxgb_fcoe_offload(struct sk_buff *skb, struct adapter *adap,
                  const struct port_info *pi, u64 *cntrl)
{
        const struct cxgb_fcoe *fcoe = &pi->fcoe;

        if (!(fcoe->flags & CXGB_FCOE_ENABLED))
                return 0;

        if (skb->protocol != htons(ETH_P_FCOE))
                return 0;

        skb_reset_mac_header(skb);
        skb->mac_len = sizeof(struct ethhdr);

        skb_set_network_header(skb, skb->mac_len);
        skb_set_transport_header(skb, skb->mac_len + sizeof(struct fcoe_hdr));

        if (!cxgb_fcoe_sof_eof_supported(adap, skb))
                return -ENOTSUPP;

        /* FC CRC offload */
        *cntrl = TXPKT_CSUM_TYPE_V(TX_CSUM_FCOE) |
                     TXPKT_L4CSUM_DIS_F | TXPKT_IPCSUM_DIS_F |
                     TXPKT_CSUM_START_V(CXGB_FCOE_TXPKT_CSUM_START) |
                     TXPKT_CSUM_END_V(CXGB_FCOE_TXPKT_CSUM_END) |
                     TXPKT_CSUM_LOC_V(CXGB_FCOE_TXPKT_CSUM_END);
        return 0;
}
#endif /* CONFIG_CHELSIO_T4_FCOE */

/* Returns tunnel type if hardware supports offloading of the same.
 * It is called only for T5 and onwards.
 */
enum cpl_tx_tnl_lso_type cxgb_encap_offload_supported(struct sk_buff *skb)
{
        u8 l4_hdr = 0;
        enum cpl_tx_tnl_lso_type tnl_type = TX_TNL_TYPE_OPAQUE;
        struct port_info *pi = netdev_priv(skb->dev);
        struct adapter *adapter = pi->adapter;

        if (skb->inner_protocol_type != ENCAP_TYPE_ETHER ||
            skb->inner_protocol != htons(ETH_P_TEB))
                return tnl_type;

        switch (vlan_get_protocol(skb)) {
        case htons(ETH_P_IP):
                l4_hdr = ip_hdr(skb)->protocol;
                break;
        case htons(ETH_P_IPV6):
                l4_hdr = ipv6_hdr(skb)->nexthdr;
                break;
        default:
                return tnl_type;
        }

        switch (l4_hdr) {
        case IPPROTO_UDP:
                if (adapter->vxlan_port == udp_hdr(skb)->dest)
                        tnl_type = TX_TNL_TYPE_VXLAN;
                else if (adapter->geneve_port == udp_hdr(skb)->dest)
                        tnl_type = TX_TNL_TYPE_GENEVE;
                break;
        default:
                return tnl_type;
        }

        return tnl_type;
}

static inline void t6_fill_tnl_lso(struct sk_buff *skb,
                                   struct cpl_tx_tnl_lso *tnl_lso,
                                   enum cpl_tx_tnl_lso_type tnl_type)
{
        u32 val;
        int in_eth_xtra_len;
        int l3hdr_len = skb_network_header_len(skb);
        int eth_xtra_len = skb_network_offset(skb) - ETH_HLEN;
        const struct skb_shared_info *ssi = skb_shinfo(skb);
        bool v6 = (ip_hdr(skb)->version == 6);

        val = CPL_TX_TNL_LSO_OPCODE_V(CPL_TX_TNL_LSO) |
              CPL_TX_TNL_LSO_FIRST_F |
              CPL_TX_TNL_LSO_LAST_F |
              (v6 ? CPL_TX_TNL_LSO_IPV6OUT_F : 0) |
              CPL_TX_TNL_LSO_ETHHDRLENOUT_V(eth_xtra_len / 4) |
              CPL_TX_TNL_LSO_IPHDRLENOUT_V(l3hdr_len / 4) |
              (v6 ? 0 : CPL_TX_TNL_LSO_IPHDRCHKOUT_F) |
              CPL_TX_TNL_LSO_IPLENSETOUT_F |
              (v6 ? 0 : CPL_TX_TNL_LSO_IPIDINCOUT_F);
        tnl_lso->op_to_IpIdSplitOut = htonl(val);

        tnl_lso->IpIdOffsetOut = 0;

        /* Get the tunnel header length */
        val = skb_inner_mac_header(skb) - skb_mac_header(skb);
        in_eth_xtra_len = skb_inner_network_header(skb) -
                          skb_inner_mac_header(skb) - ETH_HLEN;

        switch (tnl_type) {
        case TX_TNL_TYPE_VXLAN:
        case TX_TNL_TYPE_GENEVE:
                tnl_lso->UdpLenSetOut_to_TnlHdrLen =
                        htons(CPL_TX_TNL_LSO_UDPCHKCLROUT_F |
                        CPL_TX_TNL_LSO_UDPLENSETOUT_F);
                break;
        default:
                tnl_lso->UdpLenSetOut_to_TnlHdrLen = 0;
                break;
        }

        tnl_lso->UdpLenSetOut_to_TnlHdrLen |=
                 htons(CPL_TX_TNL_LSO_TNLHDRLEN_V(val) |
                       CPL_TX_TNL_LSO_TNLTYPE_V(tnl_type));

        tnl_lso->r1 = 0;

        val = CPL_TX_TNL_LSO_ETHHDRLEN_V(in_eth_xtra_len / 4) |
              CPL_TX_TNL_LSO_IPV6_V(inner_ip_hdr(skb)->version == 6) |
              CPL_TX_TNL_LSO_IPHDRLEN_V(skb_inner_network_header_len(skb) / 4) |
              CPL_TX_TNL_LSO_TCPHDRLEN_V(inner_tcp_hdrlen(skb) / 4);
        tnl_lso->Flow_to_TcpHdrLen = htonl(val);

        tnl_lso->IpIdOffset = htons(0);

        tnl_lso->IpIdSplit_to_Mss = htons(CPL_TX_TNL_LSO_MSS_V(ssi->gso_size));
        tnl_lso->TCPSeqOffset = htonl(0);
        tnl_lso->EthLenOffset_Size = htonl(CPL_TX_TNL_LSO_SIZE_V(skb->len));
}

/**
 *      t4_sge_eth_txq_egress_update - handle Ethernet TX Queue update
 *      @adap: the adapter
 *      @eq: the Ethernet TX Queue
 *      @maxreclaim: the maximum number of TX Descriptors to reclaim or -1
 *
 *      We're typically called here to update the state of an Ethernet TX
 *      Queue with respect to the hardware's progress in consuming the TX
 *      Work Requests that we've put on that Egress Queue.  This happens
 *      when we get Egress Queue Update messages and also prophylactically
 *      in regular timer-based Ethernet TX Queue maintenance.
 */
int t4_sge_eth_txq_egress_update(struct adapter *adap, struct sge_eth_txq *eq,
                                 int maxreclaim)
{
        struct sge_txq *q = &eq->q;
        unsigned int reclaimed;

        if (!q->in_use || !__netif_tx_trylock(eq->txq))
                return 0;

        /* Reclaim pending completed TX Descriptors. */
        reclaimed = reclaim_completed_tx(adap, &eq->q, maxreclaim, true);

        /* If the TX Queue is currently stopped and there's now more than half
         * the queue available, restart it.  Otherwise bail out since the rest
         * of what we want do here is with the possibility of shipping any
         * currently buffered Coalesced TX Work Request.
         */
        if (netif_tx_queue_stopped(eq->txq) && txq_avail(q) > (q->size / 2)) {
                netif_tx_wake_queue(eq->txq);
                eq->q.restarts++;
        }

        __netif_tx_unlock(eq->txq);
        return reclaimed;
}

/**
 *      cxgb4_eth_xmit - add a packet to an Ethernet Tx queue
 *      @skb: the packet
 *      @dev: the egress net device
 *
 *      Add a packet to an SGE Ethernet Tx queue.  Runs with softirqs disabled.
 */
static netdev_tx_t cxgb4_eth_xmit(struct sk_buff *skb, struct net_device *dev)
{
        u32 wr_mid, ctrl0, op;
        u64 cntrl, *end, *sgl;
        int qidx, credits;
        unsigned int flits, ndesc;
        struct adapter *adap;
        struct sge_eth_txq *q;
        const struct port_info *pi;
        struct fw_eth_tx_pkt_wr *wr;
        struct cpl_tx_pkt_core *cpl;
        const struct skb_shared_info *ssi;
        dma_addr_t addr[MAX_SKB_FRAGS + 1];
        bool immediate = false;
        int len, max_pkt_len;
        bool ptp_enabled = is_ptp_enabled(skb, dev);
        unsigned int chip_ver;
        enum cpl_tx_tnl_lso_type tnl_type = TX_TNL_TYPE_OPAQUE;

#ifdef CONFIG_CHELSIO_T4_FCOE
        int err;
#endif /* CONFIG_CHELSIO_T4_FCOE */

        /*
         * The chip min packet length is 10 octets but play safe and reject
         * anything shorter than an Ethernet header.
         */
        if (unlikely(skb->len < ETH_HLEN)) {
out_free:       dev_kfree_skb_any(skb);
                return NETDEV_TX_OK;
        }

        /* Discard the packet if the length is greater than mtu */
        max_pkt_len = ETH_HLEN + dev->mtu;
        if (skb_vlan_tagged(skb))
                max_pkt_len += VLAN_HLEN;
        if (!skb_shinfo(skb)->gso_size && (unlikely(skb->len > max_pkt_len)))
                goto out_free;

        pi = netdev_priv(dev);
        adap = pi->adapter;
        ssi = skb_shinfo(skb);
#ifdef CONFIG_CHELSIO_IPSEC_INLINE
        if (xfrm_offload(skb) && !ssi->gso_size)
                return adap->uld[CXGB4_ULD_CRYPTO].tx_handler(skb, dev);
#endif /* CHELSIO_IPSEC_INLINE */

        qidx = skb_get_queue_mapping(skb);
        if (ptp_enabled) {
                spin_lock(&adap->ptp_lock);
                if (!(adap->ptp_tx_skb)) {
                        skb_shinfo(skb)->tx_flags |= SKBTX_IN_PROGRESS;
                        adap->ptp_tx_skb = skb_get(skb);
                } else {
                        spin_unlock(&adap->ptp_lock);
                        goto out_free;
                }
                q = &adap->sge.ptptxq;
        } else {
                q = &adap->sge.ethtxq[qidx + pi->first_qset];
        }
        skb_tx_timestamp(skb);

        reclaim_completed_tx(adap, &q->q, -1, true);
        cntrl = TXPKT_L4CSUM_DIS_F | TXPKT_IPCSUM_DIS_F;

#ifdef CONFIG_CHELSIO_T4_FCOE
        err = cxgb_fcoe_offload(skb, adap, pi, &cntrl);
        if (unlikely(err == -ENOTSUPP)) {
                if (ptp_enabled)
                        spin_unlock(&adap->ptp_lock);
                goto out_free;
        }
#endif /* CONFIG_CHELSIO_T4_FCOE */

        chip_ver = CHELSIO_CHIP_VERSION(adap->params.chip);
        flits = calc_tx_flits(skb, chip_ver);
        ndesc = flits_to_desc(flits);
        credits = txq_avail(&q->q) - ndesc;

        if (unlikely(credits < 0)) {
                eth_txq_stop(q);
                dev_err(adap->pdev_dev,
                        "%s: Tx ring %u full while queue awake!\n",
                        dev->name, qidx);
                if (ptp_enabled)
                        spin_unlock(&adap->ptp_lock);
                return NETDEV_TX_BUSY;
        }

        if (is_eth_imm(skb, chip_ver))
                immediate = true;

        if (skb->encapsulation && chip_ver > CHELSIO_T5)
                tnl_type = cxgb_encap_offload_supported(skb);

        if (!immediate &&
            unlikely(cxgb4_map_skb(adap->pdev_dev, skb, addr) < 0)) {
                q->mapping_err++;
                if (ptp_enabled)
                        spin_unlock(&adap->ptp_lock);
                goto out_free;
        }

        wr_mid = FW_WR_LEN16_V(DIV_ROUND_UP(flits, 2));
        if (unlikely(credits < ETHTXQ_STOP_THRES)) {
                /* After we're done injecting the Work Request for this
                 * packet, we'll be below our "stop threshold" so stop the TX
                 * Queue now and schedule a request for an SGE Egress Queue
                 * Update message. The queue will get started later on when
                 * the firmware processes this Work Request and sends us an
                 * Egress Queue Status Update message indicating that space
                 * has opened up.
                 */
                eth_txq_stop(q);

                /* If we're using the SGE Doorbell Queue Timer facility, we
                 * don't need to ask the Firmware to send us Egress Queue CIDX
                 * Updates: the Hardware will do this automatically.  And
                 * since we send the Ingress Queue CIDX Updates to the
                 * corresponding Ethernet Response Queue, we'll get them very
                 * quickly.
                 */
                if (!q->dbqt)
                        wr_mid |= FW_WR_EQUEQ_F | FW_WR_EQUIQ_F;
        }

        wr = (void *)&q->q.desc[q->q.pidx];
        wr->equiq_to_len16 = htonl(wr_mid);
        wr->r3 = cpu_to_be64(0);
        end = (u64 *)wr + flits;

        len = immediate ? skb->len : 0;
        len += sizeof(*cpl);
        if (ssi->gso_size) {
                struct cpl_tx_pkt_lso_core *lso = (void *)(wr + 1);
                bool v6 = (ssi->gso_type & SKB_GSO_TCPV6) != 0;
                int l3hdr_len = skb_network_header_len(skb);
                int eth_xtra_len = skb_network_offset(skb) - ETH_HLEN;
                struct cpl_tx_tnl_lso *tnl_lso = (void *)(wr + 1);

                if (tnl_type)
                        len += sizeof(*tnl_lso);
                else
                        len += sizeof(*lso);

                wr->op_immdlen = htonl(FW_WR_OP_V(FW_ETH_TX_PKT_WR) |
                                       FW_WR_IMMDLEN_V(len));
                if (tnl_type) {
                        struct iphdr *iph = ip_hdr(skb);

                        t6_fill_tnl_lso(skb, tnl_lso, tnl_type);
                        cpl = (void *)(tnl_lso + 1);
                        /* Driver is expected to compute partial checksum that
                         * does not include the IP Total Length.
                         */
                        if (iph->version == 4) {
                                iph->check = 0;
                                iph->tot_len = 0;
                                iph->check = (u16)(~ip_fast_csum((u8 *)iph,
                                                                 iph->ihl));
                        }
                        if (skb->ip_summed == CHECKSUM_PARTIAL)
                                cntrl = hwcsum(adap->params.chip, skb);
                } else {
                        lso->lso_ctrl = htonl(LSO_OPCODE_V(CPL_TX_PKT_LSO) |
                                        LSO_FIRST_SLICE_F | LSO_LAST_SLICE_F |
                                        LSO_IPV6_V(v6) |
                                        LSO_ETHHDR_LEN_V(eth_xtra_len / 4) |
                                        LSO_IPHDR_LEN_V(l3hdr_len / 4) |
                                        LSO_TCPHDR_LEN_V(tcp_hdr(skb)->doff));
                        lso->ipid_ofst = htons(0);
                        lso->mss = htons(ssi->gso_size);
                        lso->seqno_offset = htonl(0);
                        if (is_t4(adap->params.chip))
                                lso->len = htonl(skb->len);
                        else
                                lso->len = htonl(LSO_T5_XFER_SIZE_V(skb->len));
                        cpl = (void *)(lso + 1);

                        if (CHELSIO_CHIP_VERSION(adap->params.chip)
                            <= CHELSIO_T5)
                                cntrl = TXPKT_ETHHDR_LEN_V(eth_xtra_len);
                        else
                                cntrl = T6_TXPKT_ETHHDR_LEN_V(eth_xtra_len);

                        cntrl |= TXPKT_CSUM_TYPE_V(v6 ?
                                 TX_CSUM_TCPIP6 : TX_CSUM_TCPIP) |
                                 TXPKT_IPHDR_LEN_V(l3hdr_len);
                }
                sgl = (u64 *)(cpl + 1); /* sgl start here */
                if (unlikely((u8 *)sgl >= (u8 *)q->q.stat)) {
                        /* If current position is already at the end of the
                         * txq, reset the current to point to start of the queue
                         * and update the end ptr as well.
                         */
                        if (sgl == (u64 *)q->q.stat) {
                                int left = (u8 *)end - (u8 *)q->q.stat;

                                end = (void *)q->q.desc + left;
                                sgl = (void *)q->q.desc;
                        }
                }
                q->tso++;
                q->tx_cso += ssi->gso_segs;
        } else {
                if (ptp_enabled)
                        op = FW_PTP_TX_PKT_WR;
                else
                        op = FW_ETH_TX_PKT_WR;
                wr->op_immdlen = htonl(FW_WR_OP_V(op) |
                                       FW_WR_IMMDLEN_V(len));
                cpl = (void *)(wr + 1);
                sgl = (u64 *)(cpl + 1);
                if (skb->ip_summed == CHECKSUM_PARTIAL) {
                        cntrl = hwcsum(adap->params.chip, skb) |
                                TXPKT_IPCSUM_DIS_F;
                        q->tx_cso++;
                }
        }

        if (skb_vlan_tag_present(skb)) {
                q->vlan_ins++;
                cntrl |= TXPKT_VLAN_VLD_F | TXPKT_VLAN_V(skb_vlan_tag_get(skb));
#ifdef CONFIG_CHELSIO_T4_FCOE
                if (skb->protocol == htons(ETH_P_FCOE))
                        cntrl |= TXPKT_VLAN_V(
                                 ((skb->priority & 0x7) << VLAN_PRIO_SHIFT));
#endif /* CONFIG_CHELSIO_T4_FCOE */
        }

        ctrl0 = TXPKT_OPCODE_V(CPL_TX_PKT_XT) | TXPKT_INTF_V(pi->tx_chan) |
                TXPKT_PF_V(adap->pf);
        if (ptp_enabled)
                ctrl0 |= TXPKT_TSTAMP_F;
#ifdef CONFIG_CHELSIO_T4_DCB
        if (is_t4(adap->params.chip))
                ctrl0 |= TXPKT_OVLAN_IDX_V(q->dcb_prio);
        else
                ctrl0 |= TXPKT_T5_OVLAN_IDX_V(q->dcb_prio);
#endif
        cpl->ctrl0 = htonl(ctrl0);
        cpl->pack = htons(0);
        cpl->len = htons(skb->len);
        cpl->ctrl1 = cpu_to_be64(cntrl);

        if (immediate) {
                cxgb4_inline_tx_skb(skb, &q->q, sgl);
                dev_consume_skb_any(skb);
        } else {
                int last_desc;

                cxgb4_write_sgl(skb, &q->q, (void *)sgl, end, 0, addr);
                skb_orphan(skb);

                last_desc = q->q.pidx + ndesc - 1;
                if (last_desc >= q->q.size)
                        last_desc -= q->q.size;
                q->q.sdesc[last_desc].skb = skb;
                q->q.sdesc[last_desc].sgl = (struct ulptx_sgl *)sgl;
        }

        txq_advance(&q->q, ndesc);

        cxgb4_ring_tx_db(adap, &q->q, ndesc);
        if (ptp_enabled)
                spin_unlock(&adap->ptp_lock);
        return NETDEV_TX_OK;
}

/* Constants ... */
enum {
        /* Egress Queue sizes, producer and consumer indices are all in units
         * of Egress Context Units bytes.  Note that as far as the hardware is
         * concerned, the free list is an Egress Queue (the host produces free
         * buffers which the hardware consumes) and free list entries are
         * 64-bit PCI DMA addresses.
         */
        EQ_UNIT = SGE_EQ_IDXSIZE,
        FL_PER_EQ_UNIT = EQ_UNIT / sizeof(__be64),
        TXD_PER_EQ_UNIT = EQ_UNIT / sizeof(__be64),

        T4VF_ETHTXQ_MAX_HDR = (sizeof(struct fw_eth_tx_pkt_vm_wr) +
                               sizeof(struct cpl_tx_pkt_lso_core) +
                               sizeof(struct cpl_tx_pkt_core)) / sizeof(__be64),
};

/**
 *      t4vf_is_eth_imm - can an Ethernet packet be sent as immediate data?
 *      @skb: the packet
 *
 *      Returns whether an Ethernet packet is small enough to fit completely as
 *      immediate data.
 */
static inline int t4vf_is_eth_imm(const struct sk_buff *skb)
{
        /* The VF Driver uses the FW_ETH_TX_PKT_VM_WR firmware Work Request
         * which does not accommodate immediate data.  We could dike out all
         * of the support code for immediate data but that would tie our hands
         * too much if we ever want to enhace the firmware.  It would also
         * create more differences between the PF and VF Drivers.
         */
        return false;
}

/**
 *      t4vf_calc_tx_flits - calculate the number of flits for a packet TX WR
 *      @skb: the packet
 *
 *      Returns the number of flits needed for a TX Work Request for the
 *      given Ethernet packet, including the needed WR and CPL headers.
 */
static inline unsigned int t4vf_calc_tx_flits(const struct sk_buff *skb)
{
        unsigned int flits;

        /* If the skb is small enough, we can pump it out as a work request
         * with only immediate data.  In that case we just have to have the
         * TX Packet header plus the skb data in the Work Request.
         */
        if (t4vf_is_eth_imm(skb))
                return DIV_ROUND_UP(skb->len + sizeof(struct cpl_tx_pkt),
                                    sizeof(__be64));

        /* Otherwise, we're going to have to construct a Scatter gather list
         * of the skb body and fragments.  We also include the flits necessary
         * for the TX Packet Work Request and CPL.  We always have a firmware
         * Write Header (incorporated as part of the cpl_tx_pkt_lso and
         * cpl_tx_pkt structures), followed by either a TX Packet Write CPL
         * message or, if we're doing a Large Send Offload, an LSO CPL message
         * with an embedded TX Packet Write CPL message.
         */
        flits = sgl_len(skb_shinfo(skb)->nr_frags + 1);
        if (skb_shinfo(skb)->gso_size)
                flits += (sizeof(struct fw_eth_tx_pkt_vm_wr) +
                          sizeof(struct cpl_tx_pkt_lso_core) +
                          sizeof(struct cpl_tx_pkt_core)) / sizeof(__be64);
        else
                flits += (sizeof(struct fw_eth_tx_pkt_vm_wr) +
                          sizeof(struct cpl_tx_pkt_core)) / sizeof(__be64);
        return flits;
}

/**
 *      cxgb4_vf_eth_xmit - add a packet to an Ethernet TX queue
 *      @skb: the packet
 *      @dev: the egress net device
 *
 *      Add a packet to an SGE Ethernet TX queue.  Runs with softirqs disabled.
 */
static netdev_tx_t cxgb4_vf_eth_xmit(struct sk_buff *skb,
                                     struct net_device *dev)
{
        dma_addr_t addr[MAX_SKB_FRAGS + 1];
        const struct skb_shared_info *ssi;
        struct fw_eth_tx_pkt_vm_wr *wr;
        int qidx, credits, max_pkt_len;
        struct cpl_tx_pkt_core *cpl;
        const struct port_info *pi;
        unsigned int flits, ndesc;
        struct sge_eth_txq *txq;
        struct adapter *adapter;
        u64 cntrl, *end;
        u32 wr_mid;
        const size_t fw_hdr_copy_len = sizeof(wr->ethmacdst) +
                                       sizeof(wr->ethmacsrc) +
                                       sizeof(wr->ethtype) +
                                       sizeof(wr->vlantci);

        /* The chip minimum packet length is 10 octets but the firmware
         * command that we are using requires that we copy the Ethernet header
         * (including the VLAN tag) into the header so we reject anything
         * smaller than that ...
         */
        if (unlikely(skb->len < fw_hdr_copy_len))
                goto out_free;

        /* Discard the packet if the length is greater than mtu */
        max_pkt_len = ETH_HLEN + dev->mtu;
        if (skb_vlan_tag_present(skb))
                max_pkt_len += VLAN_HLEN;
        if (!skb_shinfo(skb)->gso_size && (unlikely(skb->len > max_pkt_len)))
                goto out_free;

        /* Figure out which TX Queue we're going to use. */
        pi = netdev_priv(dev);
        adapter = pi->adapter;
        qidx = skb_get_queue_mapping(skb);
        WARN_ON(qidx >= pi->nqsets);
        txq = &adapter->sge.ethtxq[pi->first_qset + qidx];

        /* Take this opportunity to reclaim any TX Descriptors whose DMA
         * transfers have completed.
         */
        reclaim_completed_tx(adapter, &txq->q, -1, true);

        /* Calculate the number of flits and TX Descriptors we're going to
         * need along with how many TX Descriptors will be left over after
         * we inject our Work Request.
         */
        flits = t4vf_calc_tx_flits(skb);
        ndesc = flits_to_desc(flits);
        credits = txq_avail(&txq->q) - ndesc;

        if (unlikely(credits < 0)) {
                /* Not enough room for this packet's Work Request.  Stop the
                 * TX Queue and return a "busy" condition.  The queue will get
                 * started later on when the firmware informs us that space
                 * has opened up.
                 */
                eth_txq_stop(txq);
                dev_err(adapter->pdev_dev,
                        "%s: TX ring %u full while queue awake!\n",
                        dev->name, qidx);
                return NETDEV_TX_BUSY;
        }

        if (!t4vf_is_eth_imm(skb) &&
            unlikely(cxgb4_map_skb(adapter->pdev_dev, skb, addr) < 0)) {
                /* We need to map the skb into PCI DMA space (because it can't
                 * be in-lined directly into the Work Request) and the mapping
                 * operation failed.  Record the error and drop the packet.
                 */
                txq->mapping_err++;
                goto out_free;
        }

        wr_mid = FW_WR_LEN16_V(DIV_ROUND_UP(flits, 2));
        if (unlikely(credits < ETHTXQ_STOP_THRES)) {
                /* After we're done injecting the Work Request for this
                 * packet, we'll be below our "stop threshold" so stop the TX
                 * Queue now and schedule a request for an SGE Egress Queue
                 * Update message.  The queue will get started later on when
                 * the firmware processes this Work Request and sends us an
                 * Egress Queue Status Update message indicating that space
                 * has opened up.
                 */
                eth_txq_stop(txq);

                /* If we're using the SGE Doorbell Queue Timer facility, we
                 * don't need to ask the Firmware to send us Egress Queue CIDX
                 * Updates: the Hardware will do this automatically.  And
                 * since we send the Ingress Queue CIDX Updates to the
                 * corresponding Ethernet Response Queue, we'll get them very
                 * quickly.
                 */
                if (!txq->dbqt)
                        wr_mid |= FW_WR_EQUEQ_F | FW_WR_EQUIQ_F;
        }

        /* Start filling in our Work Request.  Note that we do _not_ handle
         * the WR Header wrapping around the TX Descriptor Ring.  If our
         * maximum header size ever exceeds one TX Descriptor, we'll need to
         * do something else here.
         */
        WARN_ON(DIV_ROUND_UP(T4VF_ETHTXQ_MAX_HDR, TXD_PER_EQ_UNIT) > 1);
        wr = (void *)&txq->q.desc[txq->q.pidx];
        wr->equiq_to_len16 = cpu_to_be32(wr_mid);
        wr->r3[0] = cpu_to_be32(0);
        wr->r3[1] = cpu_to_be32(0);
        skb_copy_from_linear_data(skb, (void *)wr->ethmacdst, fw_hdr_copy_len);
        end = (u64 *)wr + flits;

        /* If this is a Large Send Offload packet we'll put in an LSO CPL
         * message with an encapsulated TX Packet CPL message.  Otherwise we
         * just use a TX Packet CPL message.
         */
        ssi = skb_shinfo(skb);
        if (ssi->gso_size) {
                struct cpl_tx_pkt_lso_core *lso = (void *)(wr + 1);
                bool v6 = (ssi->gso_type & SKB_GSO_TCPV6) != 0;
                int l3hdr_len = skb_network_header_len(skb);
                int eth_xtra_len = skb_network_offset(skb) - ETH_HLEN;

                wr->op_immdlen =
                        cpu_to_be32(FW_WR_OP_V(FW_ETH_TX_PKT_VM_WR) |
                                    FW_WR_IMMDLEN_V(sizeof(*lso) +
                                                    sizeof(*cpl)));
                 /* Fill in the LSO CPL message. */
                lso->lso_ctrl =
                        cpu_to_be32(LSO_OPCODE_V(CPL_TX_PKT_LSO) |
                                    LSO_FIRST_SLICE_F |
                                    LSO_LAST_SLICE_F |
                                    LSO_IPV6_V(v6) |
                                    LSO_ETHHDR_LEN_V(eth_xtra_len / 4) |
                                    LSO_IPHDR_LEN_V(l3hdr_len / 4) |
                                    LSO_TCPHDR_LEN_V(tcp_hdr(skb)->doff));
                lso->ipid_ofst = cpu_to_be16(0);
                lso->mss = cpu_to_be16(ssi->gso_size);
                lso->seqno_offset = cpu_to_be32(0);
                if (is_t4(adapter->params.chip))
                        lso->len = cpu_to_be32(skb->len);
                else
                        lso->len = cpu_to_be32(LSO_T5_XFER_SIZE_V(skb->len));

                /* Set up TX Packet CPL pointer, control word and perform
                 * accounting.
                 */
                cpl = (void *)(lso + 1);

                if (CHELSIO_CHIP_VERSION(adapter->params.chip) <= CHELSIO_T5)
                        cntrl = TXPKT_ETHHDR_LEN_V(eth_xtra_len);
                else
                        cntrl = T6_TXPKT_ETHHDR_LEN_V(eth_xtra_len);

                cntrl |= TXPKT_CSUM_TYPE_V(v6 ?
                                           TX_CSUM_TCPIP6 : TX_CSUM_TCPIP) |
                         TXPKT_IPHDR_LEN_V(l3hdr_len);
                txq->tso++;
                txq->tx_cso += ssi->gso_segs;
        } else {
                int len;

                len = (t4vf_is_eth_imm(skb)
                       ? skb->len + sizeof(*cpl)
                       : sizeof(*cpl));
                wr->op_immdlen =
                        cpu_to_be32(FW_WR_OP_V(FW_ETH_TX_PKT_VM_WR) |
                                    FW_WR_IMMDLEN_V(len));

                /* Set up TX Packet CPL pointer, control word and perform
                 * accounting.
                 */
                cpl = (void *)(wr + 1);
                if (skb->ip_summed == CHECKSUM_PARTIAL) {
                        cntrl = hwcsum(adapter->params.chip, skb) |
                                TXPKT_IPCSUM_DIS_F;
                        txq->tx_cso++;
                } else {
                        cntrl = TXPKT_L4CSUM_DIS_F | TXPKT_IPCSUM_DIS_F;
                }
        }

        /* If there's a VLAN tag present, add that to the list of things to
         * do in this Work Request.
         */
        if (skb_vlan_tag_present(skb)) {
                txq->vlan_ins++;
                cntrl |= TXPKT_VLAN_VLD_F | TXPKT_VLAN_V(skb_vlan_tag_get(skb));
        }

         /* Fill in the TX Packet CPL message header. */
        cpl->ctrl0 = cpu_to_be32(TXPKT_OPCODE_V(CPL_TX_PKT_XT) |
                                 TXPKT_INTF_V(pi->port_id) |
                                 TXPKT_PF_V(0));
        cpl->pack = cpu_to_be16(0);
        cpl->len = cpu_to_be16(skb->len);
        cpl->ctrl1 = cpu_to_be64(cntrl);

        /* Fill in the body of the TX Packet CPL message with either in-lined
         * data or a Scatter/Gather List.
         */
        if (t4vf_is_eth_imm(skb)) {
                /* In-line the packet's data and free the skb since we don't
                 * need it any longer.
                 */
                cxgb4_inline_tx_skb(skb, &txq->q, cpl + 1);
                dev_consume_skb_any(skb);
        } else {
                /* Write the skb's Scatter/Gather list into the TX Packet CPL
                 * message and retain a pointer to the skb so we can free it
                 * later when its DMA completes.  (We store the skb pointer
                 * in the Software Descriptor corresponding to the last TX
                 * Descriptor used by the Work Request.)
                 *
                 * The retained skb will be freed when the corresponding TX
                 * Descriptors are reclaimed after their DMAs complete.
                 * However, this could take quite a while since, in general,
                 * the hardware is set up to be lazy about sending DMA
                 * completion notifications to us and we mostly perform TX
                 * reclaims in the transmit routine.
                 *
                 * This is good for performamce but means that we rely on new
                 * TX packets arriving to run the destructors of completed
                 * packets, which open up space in their sockets' send queues.
                 * Sometimes we do not get such new packets causing TX to
                 * stall.  A single UDP transmitter is a good example of this
                 * situation.  We have a clean up timer that periodically
                 * reclaims completed packets but it doesn't run often enough
                 * (nor do we want it to) to prevent lengthy stalls.  A
                 * solution to this problem is to run the destructor early,
                 * after the packet is queued but before it's DMAd.  A con is
                 * that we lie to socket memory accounting, but the amount of
                 * extra memory is reasonable (limited by the number of TX
                 * descriptors), the packets do actually get freed quickly by
                 * new packets almost always, and for protocols like TCP that
                 * wait for acks to really free up the data the extra memory
                 * is even less.  On the positive side we run the destructors
                 * on the sending CPU rather than on a potentially different
                 * completing CPU, usually a good thing.
                 *
                 * Run the destructor before telling the DMA engine about the
                 * packet to make sure it doesn't complete and get freed
                 * prematurely.
                 */
                struct ulptx_sgl *sgl = (struct ulptx_sgl *)(cpl + 1);
                struct sge_txq *tq = &txq->q;
                int last_desc;

                /* If the Work Request header was an exact multiple of our TX
                 * Descriptor length, then it's possible that the starting SGL
                 * pointer lines up exactly with the end of our TX Descriptor
                 * ring.  If that's the case, wrap around to the beginning
                 * here ...
                 */
                if (unlikely((void *)sgl == (void *)tq->stat)) {
                        sgl = (void *)tq->desc;
                        end = (void *)((void *)tq->desc +
                                       ((void *)end - (void *)tq->stat));
                }

                cxgb4_write_sgl(skb, tq, sgl, end, 0, addr);
                skb_orphan(skb);

                last_desc = tq->pidx + ndesc - 1;
                if (last_desc >= tq->size)
                        last_desc -= tq->size;
                tq->sdesc[last_desc].skb = skb;
                tq->sdesc[last_desc].sgl = sgl;
        }

        /* Advance our internal TX Queue state, tell the hardware about
         * the new TX descriptors and return success.
         */
        txq_advance(&txq->q, ndesc);

        cxgb4_ring_tx_db(adapter, &txq->q, ndesc);
        return NETDEV_TX_OK;

out_free:
        /* An error of some sort happened.  Free the TX skb and tell the
         * OS that we've "dealt" with the packet ...
         */
        dev_kfree_skb_any(skb);
        return NETDEV_TX_OK;
}

netdev_tx_t t4_start_xmit(struct sk_buff *skb, struct net_device *dev)
{
        struct port_info *pi = netdev_priv(dev);

        if (unlikely(pi->eth_flags & PRIV_FLAG_PORT_TX_VM))
                return cxgb4_vf_eth_xmit(skb, dev);

        return cxgb4_eth_xmit(skb, dev);
}

/**
 *      reclaim_completed_tx_imm - reclaim completed control-queue Tx descs
 *      @q: the SGE control Tx queue
 *
 *      This is a variant of cxgb4_reclaim_completed_tx() that is used
 *      for Tx queues that send only immediate data (presently just
 *      the control queues) and thus do not have any sk_buffs to release.
 */
static inline void reclaim_completed_tx_imm(struct sge_txq *q)
{
        int hw_cidx = ntohs(READ_ONCE(q->stat->cidx));
        int reclaim = hw_cidx - q->cidx;

        if (reclaim < 0)
                reclaim += q->size;

        q->in_use -= reclaim;
        q->cidx = hw_cidx;
}

/**
 *      is_imm - check whether a packet can be sent as immediate data
 *      @skb: the packet
 *
 *      Returns true if a packet can be sent as a WR with immediate data.
 */
static inline int is_imm(const struct sk_buff *skb)
{
        return skb->len <= MAX_CTRL_WR_LEN;
}

/**
 *      ctrlq_check_stop - check if a control queue is full and should stop
 *      @q: the queue
 *      @wr: most recent WR written to the queue
 *
 *      Check if a control queue has become full and should be stopped.
 *      We clean up control queue descriptors very lazily, only when we are out.
 *      If the queue is still full after reclaiming any completed descriptors
 *      we suspend it and have the last WR wake it up.
 */
static void ctrlq_check_stop(struct sge_ctrl_txq *q, struct fw_wr_hdr *wr)
{
        reclaim_completed_tx_imm(&q->q);
        if (unlikely(txq_avail(&q->q) < TXQ_STOP_THRES)) {
                wr->lo |= htonl(FW_WR_EQUEQ_F | FW_WR_EQUIQ_F);
                q->q.stops++;
                q->full = 1;
        }
}

/**
 *      ctrl_xmit - send a packet through an SGE control Tx queue
 *      @q: the control queue
 *      @skb: the packet
 *
 *      Send a packet through an SGE control Tx queue.  Packets sent through
 *      a control queue must fit entirely as immediate data.
 */
static int ctrl_xmit(struct sge_ctrl_txq *q, struct sk_buff *skb)
{
        unsigned int ndesc;
        struct fw_wr_hdr *wr;

        if (unlikely(!is_imm(skb))) {
                WARN_ON(1);
                dev_kfree_skb(skb);
                return NET_XMIT_DROP;
        }

        ndesc = DIV_ROUND_UP(skb->len, sizeof(struct tx_desc));
        spin_lock(&q->sendq.lock);

        if (unlikely(q->full)) {
                skb->priority = ndesc;                  /* save for restart */
                __skb_queue_tail(&q->sendq, skb);
                spin_unlock(&q->sendq.lock);
                return NET_XMIT_CN;
        }

        wr = (struct fw_wr_hdr *)&q->q.desc[q->q.pidx];
        cxgb4_inline_tx_skb(skb, &q->q, wr);

        txq_advance(&q->q, ndesc);
        if (unlikely(txq_avail(&q->q) < TXQ_STOP_THRES))
                ctrlq_check_stop(q, wr);

        cxgb4_ring_tx_db(q->adap, &q->q, ndesc);
        spin_unlock(&q->sendq.lock);

        kfree_skb(skb);
        return NET_XMIT_SUCCESS;
}

/**
 *      restart_ctrlq - restart a suspended control queue
 *      @data: the control queue to restart
 *
 *      Resumes transmission on a suspended Tx control queue.
 */
static void restart_ctrlq(unsigned long data)
{
        struct sk_buff *skb;
        unsigned int written = 0;
        struct sge_ctrl_txq *q = (struct sge_ctrl_txq *)data;

        spin_lock(&q->sendq.lock);
        reclaim_completed_tx_imm(&q->q);
        BUG_ON(txq_avail(&q->q) < TXQ_STOP_THRES);  /* q should be empty */

        while ((skb = __skb_dequeue(&q->sendq)) != NULL) {
                struct fw_wr_hdr *wr;
                unsigned int ndesc = skb->priority;     /* previously saved */

                written += ndesc;
                /* Write descriptors and free skbs outside the lock to limit
                 * wait times.  q->full is still set so new skbs will be queued.
                 */
                wr = (struct fw_wr_hdr *)&q->q.desc[q->q.pidx];
                txq_advance(&q->q, ndesc);
                spin_unlock(&q->sendq.lock);

                cxgb4_inline_tx_skb(skb, &q->q, wr);
                kfree_skb(skb);

                if (unlikely(txq_avail(&q->q) < TXQ_STOP_THRES)) {
                        unsigned long old = q->q.stops;

                        ctrlq_check_stop(q, wr);
                        if (q->q.stops != old) {          /* suspended anew */
                                spin_lock(&q->sendq.lock);
                                goto ringdb;
                        }
                }
                if (written > 16) {
                        cxgb4_ring_tx_db(q->adap, &q->q, written);
                        written = 0;
                }
                spin_lock(&q->sendq.lock);
        }
        q->full = 0;
ringdb:
        if (written)
                cxgb4_ring_tx_db(q->adap, &q->q, written);
        spin_unlock(&q->sendq.lock);
}

/**
 *      t4_mgmt_tx - send a management message
 *      @adap: the adapter
 *      @skb: the packet containing the management message
 *
 *      Send a management message through control queue 0.
 */
int t4_mgmt_tx(struct adapter *adap, struct sk_buff *skb)
{
        int ret;

        local_bh_disable();
        ret = ctrl_xmit(&adap->sge.ctrlq[0], skb);
        local_bh_enable();
        return ret;
}

/**
 *      is_ofld_imm - check whether a packet can be sent as immediate data
 *      @skb: the packet
 *
 *      Returns true if a packet can be sent as an offload WR with immediate
 *      data.  We currently use the same limit as for Ethernet packets.
 */
static inline int is_ofld_imm(const struct sk_buff *skb)
{
        struct work_request_hdr *req = (struct work_request_hdr *)skb->data;
        unsigned long opcode = FW_WR_OP_G(ntohl(req->wr_hi));

        if (opcode == FW_CRYPTO_LOOKASIDE_WR)
                return skb->len <= SGE_MAX_WR_LEN;
        else
                return skb->len <= MAX_IMM_TX_PKT_LEN;
}

/**
 *      calc_tx_flits_ofld - calculate # of flits for an offload packet
 *      @skb: the packet
 *
 *      Returns the number of flits needed for the given offload packet.
 *      These packets are already fully constructed and no additional headers
 *      will be added.
 */
static inline unsigned int calc_tx_flits_ofld(const struct sk_buff *skb)
{
        unsigned int flits, cnt;

        if (is_ofld_imm(skb))
                return DIV_ROUND_UP(skb->len, 8);

        flits = skb_transport_offset(skb) / 8U;   /* headers */
        cnt = skb_shinfo(skb)->nr_frags;
        if (skb_tail_pointer(skb) != skb_transport_header(skb))
                cnt++;
        return flits + sgl_len(cnt);
}

/**
 *      txq_stop_maperr - stop a Tx queue due to I/O MMU exhaustion
 *      @adap: the adapter
 *      @q: the queue to stop
 *
 *      Mark a Tx queue stopped due to I/O MMU exhaustion and resulting
 *      inability to map packets.  A periodic timer attempts to restart
 *      queues so marked.
 */
static void txq_stop_maperr(struct sge_uld_txq *q)
{
        q->mapping_err++;
        q->q.stops++;
        set_bit(q->q.cntxt_id - q->adap->sge.egr_start,
                q->adap->sge.txq_maperr);
}

/**
 *      ofldtxq_stop - stop an offload Tx queue that has become full
 *      @q: the queue to stop
 *      @wr: the Work Request causing the queue to become full
 *
 *      Stops an offload Tx queue that has become full and modifies the packet
 *      being written to request a wakeup.
 */
static void ofldtxq_stop(struct sge_uld_txq *q, struct fw_wr_hdr *wr)
{
        wr->lo |= htonl(FW_WR_EQUEQ_F | FW_WR_EQUIQ_F);
        q->q.stops++;
        q->full = 1;
}

/**
 *      service_ofldq - service/restart a suspended offload queue
 *      @q: the offload queue
 *
 *      Services an offload Tx queue by moving packets from its Pending Send
 *      Queue to the Hardware TX ring.  The function starts and ends with the
 *      Send Queue locked, but drops the lock while putting the skb at the
 *      head of the Send Queue onto the Hardware TX Ring.  Dropping the lock
 *      allows more skbs to be added to the Send Queue by other threads.
 *      The packet being processed at the head of the Pending Send Queue is
 *      left on the queue in case we experience DMA Mapping errors, etc.
 *      and need to give up and restart later.
 *
 *      service_ofldq() can be thought of as a task which opportunistically
 *      uses other threads execution contexts.  We use the Offload Queue
 *      boolean "service_ofldq_running" to make sure that only one instance
 *      is ever running at a time ...
 */
static void service_ofldq(struct sge_uld_txq *q)
{
        u64 *pos, *before, *end;
        int credits;
        struct sk_buff *skb;
        struct sge_txq *txq;
        unsigned int left;
        unsigned int written = 0;
        unsigned int flits, ndesc;

        /* If another thread is currently in service_ofldq() processing the
         * Pending Send Queue then there's nothing to do. Otherwise, flag
         * that we're doing the work and continue.  Examining/modifying
         * the Offload Queue boolean "service_ofldq_running" must be done
         * while holding the Pending Send Queue Lock.
         */
        if (q->service_ofldq_running)
                return;
        q->service_ofldq_running = true;

        while ((skb = skb_peek(&q->sendq)) != NULL && !q->full) {
                /* We drop the lock while we're working with the skb at the
                 * head of the Pending Send Queue.  This allows more skbs to
                 * be added to the Pending Send Queue while we're working on
                 * this one.  We don't need to lock to guard the TX Ring
                 * updates because only one thread of execution is ever
                 * allowed into service_ofldq() at a time.
                 */
                spin_unlock(&q->sendq.lock);

                cxgb4_reclaim_completed_tx(q->adap, &q->q, false);

                flits = skb->priority;                /* previously saved */
                ndesc = flits_to_desc(flits);
                credits = txq_avail(&q->q) - ndesc;
                BUG_ON(credits < 0);
                if (unlikely(credits < TXQ_STOP_THRES))
                        ofldtxq_stop(q, (struct fw_wr_hdr *)skb->data);

                pos = (u64 *)&q->q.desc[q->q.pidx];
                if (is_ofld_imm(skb))
                        cxgb4_inline_tx_skb(skb, &q->q, pos);
                else if (cxgb4_map_skb(q->adap->pdev_dev, skb,
                                       (dma_addr_t *)skb->head)) {
                        txq_stop_maperr(q);
                        spin_lock(&q->sendq.lock);
                        break;
                } else {
                        int last_desc, hdr_len = skb_transport_offset(skb);

                        /* The WR headers  may not fit within one descriptor.
                         * So we need to deal with wrap-around here.
                         */
                        before = (u64 *)pos;
                        end = (u64 *)pos + flits;
                        txq = &q->q;
                        pos = (void *)inline_tx_skb_header(skb, &q->q,
                                                           (void *)pos,
                                                           hdr_len);
                        if (before > (u64 *)pos) {
                                left = (u8 *)end - (u8 *)txq->stat;
                                end = (void *)txq->desc + left;
                        }

                        /* If current position is already at the end of the
                         * ofld queue, reset the current to point to
                         * start of the queue and update the end ptr as well.
                         */
                        if (pos == (u64 *)txq->stat) {
                                left = (u8 *)end - (u8 *)txq->stat;
                                end = (void *)txq->desc + left;
                                pos = (void *)txq->desc;
                        }

                        cxgb4_write_sgl(skb, &q->q, (void *)pos,
                                        end, hdr_len,
                                        (dma_addr_t *)skb->head);
#ifdef CONFIG_NEED_DMA_MAP_STATE
                        skb->dev = q->adap->port[0];
                        skb->destructor = deferred_unmap_destructor;
#endif
                        last_desc = q->q.pidx + ndesc - 1;
                        if (last_desc >= q->q.size)
                                last_desc -= q->q.size;
                        q->q.sdesc[last_desc].skb = skb;
                }

                txq_advance(&q->q, ndesc);
                written += ndesc;
                if (unlikely(written > 32)) {
                        cxgb4_ring_tx_db(q->adap, &q->q, written);
                        written = 0;
                }

                /* Reacquire the Pending Send Queue Lock so we can unlink the
                 * skb we've just successfully transferred to the TX Ring and
                 * loop for the next skb which may be at the head of the
                 * Pending Send Queue.
                 */
                spin_lock(&q->sendq.lock);
                __skb_unlink(skb, &q->sendq);
                if (is_ofld_imm(skb))
                        kfree_skb(skb);
        }
        if (likely(written))
                cxgb4_ring_tx_db(q->adap, &q->q, written);

        /*Indicate that no thread is processing the Pending Send Queue
         * currently.
         */
        q->service_ofldq_running = false;
}

/**
 *      ofld_xmit - send a packet through an offload queue
 *      @q: the Tx offload queue
 *      @skb: the packet
 *
 *      Send an offload packet through an SGE offload queue.
 */
static int ofld_xmit(struct sge_uld_txq *q, struct sk_buff *skb)
{
        skb->priority = calc_tx_flits_ofld(skb);       /* save for restart */
        spin_lock(&q->sendq.lock);

        /* Queue the new skb onto the Offload Queue's Pending Send Queue.  If
         * that results in this new skb being the only one on the queue, start
         * servicing it.  If there are other skbs already on the list, then
         * either the queue is currently being processed or it's been stopped
         * for some reason and it'll be restarted at a later time.  Restart
         * paths are triggered by events like experiencing a DMA Mapping Error
         * or filling the Hardware TX Ring.
         */
        __skb_queue_tail(&q->sendq, skb);
        if (q->sendq.qlen == 1)
                service_ofldq(q);

        spin_unlock(&q->sendq.lock);
        return NET_XMIT_SUCCESS;
}

/**
 *      restart_ofldq - restart a suspended offload queue
 *      @data: the offload queue to restart
 *
 *      Resumes transmission on a suspended Tx offload queue.
 */
static void restart_ofldq(unsigned long data)
{
        struct sge_uld_txq *q = (struct sge_uld_txq *)data;

        spin_lock(&q->sendq.lock);
        q->full = 0;            /* the queue actually is completely empty now */
        service_ofldq(q);
        spin_unlock(&q->sendq.lock);
}

/**
 *      skb_txq - return the Tx queue an offload packet should use
 *      @skb: the packet
 *
 *      Returns the Tx queue an offload packet should use as indicated by bits
 *      1-15 in the packet's queue_mapping.
 */
static inline unsigned int skb_txq(const struct sk_buff *skb)
{
        return skb->queue_mapping >> 1;
}

/**
 *      is_ctrl_pkt - return whether an offload packet is a control packet
 *      @skb: the packet
 *
 *      Returns whether an offload packet should use an OFLD or a CTRL
 *      Tx queue as indicated by bit 0 in the packet's queue_mapping.
 */
static inline unsigned int is_ctrl_pkt(const struct sk_buff *skb)
{
        return skb->queue_mapping & 1;
}

static inline int uld_send(struct adapter *adap, struct sk_buff *skb,
                           unsigned int tx_uld_type)
{
        struct sge_uld_txq_info *txq_info;
        struct sge_uld_txq *txq;
        unsigned int idx = skb_txq(skb);

        if (unlikely(is_ctrl_pkt(skb))) {
                /* Single ctrl queue is a requirement for LE workaround path */
                if (adap->tids.nsftids)
                        idx = 0;
                return ctrl_xmit(&adap->sge.ctrlq[idx], skb);
        }

        txq_info = adap->sge.uld_txq_info[tx_uld_type];
        if (unlikely(!txq_info)) {
                WARN_ON(true);
                return NET_XMIT_DROP;
        }

        txq = &txq_info->uldtxq[idx];
        return ofld_xmit(txq, skb);
}

/**
 *      t4_ofld_send - send an offload packet
 *      @adap: the adapter
 *      @skb: the packet
 *
 *      Sends an offload packet.  We use the packet queue_mapping to select the
 *      appropriate Tx queue as follows: bit 0 indicates whether the packet
 *      should be sent as regular or control, bits 1-15 select the queue.
 */
int t4_ofld_send(struct adapter *adap, struct sk_buff *skb)
{
        int ret;

        local_bh_disable();
        ret = uld_send(adap, skb, CXGB4_TX_OFLD);
        local_bh_enable();
        return ret;
}

/**
 *      cxgb4_ofld_send - send an offload packet
 *      @dev: the net device
 *      @skb: the packet
 *
 *      Sends an offload packet.  This is an exported version of @t4_ofld_send,
 *      intended for ULDs.
 */
int cxgb4_ofld_send(struct net_device *dev, struct sk_buff *skb)
{
        return t4_ofld_send(netdev2adap(dev), skb);
}
EXPORT_SYMBOL(cxgb4_ofld_send);

static void *inline_tx_header(const void *src,
                              const struct sge_txq *q,
                              void *pos, int length)
{
        int left = (void *)q->stat - pos;
        u64 *p;

        if (likely(length <= left)) {
                memcpy(pos, src, length);
                pos += length;
        } else {
                memcpy(pos, src, left);
                memcpy(q->desc, src + left, length - left);
                pos = (void *)q->desc + (length - left);
        }
        /* 0-pad to multiple of 16 */
        p = PTR_ALIGN(pos, 8);
        if ((uintptr_t)p & 8) {
                *p = 0;
                return p + 1;
        }
        return p;
}

/**
 *      ofld_xmit_direct - copy a WR into offload queue
 *      @q: the Tx offload queue
 *      @src: location of WR
 *      @len: WR length
 *
 *      Copy an immediate WR into an uncontended SGE offload queue.
 */
static int ofld_xmit_direct(struct sge_uld_txq *q, const void *src,
                            unsigned int len)
{
        unsigned int ndesc;
        int credits;
        u64 *pos;

        /* Use the lower limit as the cut-off */
        if (len > MAX_IMM_OFLD_TX_DATA_WR_LEN) {
                WARN_ON(1);
                return NET_XMIT_DROP;
        }

        /* Don't return NET_XMIT_CN here as the current
         * implementation doesn't queue the request
         * using an skb when the following conditions not met
         */
        if (!spin_trylock(&q->sendq.lock))
                return NET_XMIT_DROP;

        if (q->full || !skb_queue_empty(&q->sendq) ||
            q->service_ofldq_running) {
                spin_unlock(&q->sendq.lock);
                return NET_XMIT_DROP;
        }
        ndesc = flits_to_desc(DIV_ROUND_UP(len, 8));
        credits = txq_avail(&q->q) - ndesc;
        pos = (u64 *)&q->q.desc[q->q.pidx];

        /* ofldtxq_stop modifies WR header in-situ */
        inline_tx_header(src, &q->q, pos, len);
        if (unlikely(credits < TXQ_STOP_THRES))
                ofldtxq_stop(q, (struct fw_wr_hdr *)pos);
        txq_advance(&q->q, ndesc);
        cxgb4_ring_tx_db(q->adap, &q->q, ndesc);

        spin_unlock(&q->sendq.lock);
        return NET_XMIT_SUCCESS;
}

int cxgb4_immdata_send(struct net_device *dev, unsigned int idx,
                       const void *src, unsigned int len)
{
        struct sge_uld_txq_info *txq_info;
        struct sge_uld_txq *txq;
        struct adapter *adap;
        int ret;

        adap = netdev2adap(dev);

        local_bh_disable();
        txq_info = adap->sge.uld_txq_info[CXGB4_TX_OFLD];
        if (unlikely(!txq_info)) {
                WARN_ON(true);
                local_bh_enable();
                return NET_XMIT_DROP;
        }
        txq = &txq_info->uldtxq[idx];

        ret = ofld_xmit_direct(txq, src, len);
        local_bh_enable();
        return net_xmit_eval(ret);
}
EXPORT_SYMBOL(cxgb4_immdata_send);

/**
 *      t4_crypto_send - send crypto packet
 *      @adap: the adapter
 *      @skb: the packet
 *
 *      Sends crypto packet.  We use the packet queue_mapping to select the
 *      appropriate Tx queue as follows: bit 0 indicates whether the packet
 *      should be sent as regular or control, bits 1-15 select the queue.
 */
static int t4_crypto_send(struct adapter *adap, struct sk_buff *skb)
{
        int ret;

        local_bh_disable();
        ret = uld_send(adap, skb, CXGB4_TX_CRYPTO);
        local_bh_enable();
        return ret;
}

/**
 *      cxgb4_crypto_send - send crypto packet
 *      @dev: the net device
 *      @skb: the packet
 *
 *      Sends crypto packet.  This is an exported version of @t4_crypto_send,
 *      intended for ULDs.
 */
int cxgb4_crypto_send(struct net_device *dev, struct sk_buff *skb)
{
        return t4_crypto_send(netdev2adap(dev), skb);
}
EXPORT_SYMBOL(cxgb4_crypto_send);

static inline void copy_frags(struct sk_buff *skb,
                              const struct pkt_gl *gl, unsigned int offset)
{
        int i;

        /* usually there's just one frag */
        __skb_fill_page_desc(skb, 0, gl->frags[0].page,
                             gl->frags[0].offset + offset,
                             gl->frags[0].size - offset);
        skb_shinfo(skb)->nr_frags = gl->nfrags;
        for (i = 1; i < gl->nfrags; i++)
                __skb_fill_page_desc(skb, i, gl->frags[i].page,
                                     gl->frags[i].offset,
                                     gl->frags[i].size);

        /* get a reference to the last page, we don't own it */
        get_page(gl->frags[gl->nfrags - 1].page);
}

/**
 *      cxgb4_pktgl_to_skb - build an sk_buff from a packet gather list
 *      @gl: the gather list
 *      @skb_len: size of sk_buff main body if it carries fragments
 *      @pull_len: amount of data to move to the sk_buff's main body
 *
 *      Builds an sk_buff from the given packet gather list.  Returns the
 *      sk_buff or %NULL if sk_buff allocation failed.
 */
struct sk_buff *cxgb4_pktgl_to_skb(const struct pkt_gl *gl,
                                   unsigned int skb_len, unsigned int pull_len)
{
        struct sk_buff *skb;

        /*
         * Below we rely on RX_COPY_THRES being less than the smallest Rx buffer
         * size, which is expected since buffers are at least PAGE_SIZEd.
         * In this case packets up to RX_COPY_THRES have only one fragment.
         */
        if (gl->tot_len <= RX_COPY_THRES) {
                skb = dev_alloc_skb(gl->tot_len);
                if (unlikely(!skb))
                        goto out;
                __skb_put(skb, gl->tot_len);
                skb_copy_to_linear_data(skb, gl->va, gl->tot_len);
        } else {
                skb = dev_alloc_skb(skb_len);
                if (unlikely(!skb))
                        goto out;
                __skb_put(skb, pull_len);
                skb_copy_to_linear_data(skb, gl->va, pull_len);

                copy_frags(skb, gl, pull_len);
                skb->len = gl->tot_len;
                skb->data_len = skb->len - pull_len;
                skb->truesize += skb->data_len;
        }
out:    return skb;
}
EXPORT_SYMBOL(cxgb4_pktgl_to_skb);

/**
 *      t4_pktgl_free - free a packet gather list
 *      @gl: the gather list
 *
 *      Releases the pages of a packet gather list.  We do not own the last
 *      page on the list and do not free it.
 */
static void t4_pktgl_free(const struct pkt_gl *gl)
{
        int n;
        const struct page_frag *p;

        for (p = gl->frags, n = gl->nfrags - 1; n--; p++)
                put_page(p->page);
}

/*
 * Process an MPS trace packet.  Give it an unused protocol number so it won't
 * be delivered to anyone and send it to the stack for capture.
 */
static noinline int handle_trace_pkt(struct adapter *adap,
                                     const struct pkt_gl *gl)
{
        struct sk_buff *skb;

        skb = cxgb4_pktgl_to_skb(gl, RX_PULL_LEN, RX_PULL_LEN);
        if (unlikely(!skb)) {
                t4_pktgl_free(gl);
                return 0;
        }

        if (is_t4(adap->params.chip))
                __skb_pull(skb, sizeof(struct cpl_trace_pkt));
        else
                __skb_pull(skb, sizeof(struct cpl_t5_trace_pkt));

        skb_reset_mac_header(skb);
        skb->protocol = htons(0xffff);
        skb->dev = adap->port[0];
        netif_receive_skb(skb);
        return 0;
}

/**
 * cxgb4_sgetim_to_hwtstamp - convert sge time stamp to hw time stamp
 * @adap: the adapter
 * @hwtstamps: time stamp structure to update
 * @sgetstamp: 60bit iqe timestamp
 *
 * Every ingress queue entry has the 60-bit timestamp, convert that timestamp
 * which is in Core Clock ticks into ktime_t and assign it
 **/
static void cxgb4_sgetim_to_hwtstamp(struct adapter *adap,
                                     struct skb_shared_hwtstamps *hwtstamps,
                                     u64 sgetstamp)
{
        u64 ns;
        u64 tmp = (sgetstamp * 1000 * 1000 + adap->params.vpd.cclk / 2);

        ns = div_u64(tmp, adap->params.vpd.cclk);

        memset(hwtstamps, 0, sizeof(*hwtstamps));
        hwtstamps->hwtstamp = ns_to_ktime(ns);
}

static void do_gro(struct sge_eth_rxq *rxq, const struct pkt_gl *gl,
                   const struct cpl_rx_pkt *pkt, unsigned long tnl_hdr_len)
{
        struct adapter *adapter = rxq->rspq.adap;
        struct sge *s = &adapter->sge;
        struct port_info *pi;
        int ret;
        struct sk_buff *skb;

        skb = napi_get_frags(&rxq->rspq.napi);
        if (unlikely(!skb)) {
                t4_pktgl_free(gl);
                rxq->stats.rx_drops++;
                return;
        }

        copy_frags(skb, gl, s->pktshift);
        if (tnl_hdr_len)
                skb->csum_level = 1;
        skb->len = gl->tot_len - s->pktshift;
        skb->data_len = skb->len;
        skb->truesize += skb->data_len;
        skb->ip_summed = CHECKSUM_UNNECESSARY;
        skb_record_rx_queue(skb, rxq->rspq.idx);
        pi = netdev_priv(skb->dev);
        if (pi->rxtstamp)
                cxgb4_sgetim_to_hwtstamp(adapter, skb_hwtstamps(skb),
                                         gl->sgetstamp);
        if (rxq->rspq.netdev->features & NETIF_F_RXHASH)
                skb_set_hash(skb, (__force u32)pkt->rsshdr.hash_val,
                             PKT_HASH_TYPE_L3);

        if (unlikely(pkt->vlan_ex)) {
                __vlan_hwaccel_put_tag(skb, htons(ETH_P_8021Q), ntohs(pkt->vlan));
                rxq->stats.vlan_ex++;
        }
        ret = napi_gro_frags(&rxq->rspq.napi);
        if (ret == GRO_HELD)
                rxq->stats.lro_pkts++;
        else if (ret == GRO_MERGED || ret == GRO_MERGED_FREE)
                rxq->stats.lro_merged++;
        rxq->stats.pkts++;
        rxq->stats.rx_cso++;
}

enum {
        RX_NON_PTP_PKT = 0,
        RX_PTP_PKT_SUC = 1,
        RX_PTP_PKT_ERR = 2
};

/**
 *     t4_systim_to_hwstamp - read hardware time stamp
 *     @adap: the adapter
 *     @skb: the packet
 *
 *     Read Time Stamp from MPS packet and insert in skb which
 *     is forwarded to PTP application
 */
static noinline int t4_systim_to_hwstamp(struct adapter *adapter,
                                         struct sk_buff *skb)
{
        struct skb_shared_hwtstamps *hwtstamps;
        struct cpl_rx_mps_pkt *cpl = NULL;
        unsigned char *data;
        int offset;

        cpl = (struct cpl_rx_mps_pkt *)skb->data;
        if (!(CPL_RX_MPS_PKT_TYPE_G(ntohl(cpl->op_to_r1_hi)) &
             X_CPL_RX_MPS_PKT_TYPE_PTP))
                return RX_PTP_PKT_ERR;

        data = skb->data + sizeof(*cpl);
        skb_pull(skb, 2 * sizeof(u64) + sizeof(struct cpl_rx_mps_pkt));
        offset = ETH_HLEN + IPV4_HLEN(skb->data) + UDP_HLEN;
        if (skb->len < offset + OFF_PTP_SEQUENCE_ID + sizeof(short))
                return RX_PTP_PKT_ERR;

        hwtstamps = skb_hwtstamps(skb);
        memset(hwtstamps, 0, sizeof(*hwtstamps));
        hwtstamps->hwtstamp = ns_to_ktime(be64_to_cpu(*((u64 *)data)));

        return RX_PTP_PKT_SUC;
}

/**
 *     t4_rx_hststamp - Recv PTP Event Message
 *     @adap: the adapter
 *     @rsp: the response queue descriptor holding the RX_PKT message
 *     @skb: the packet
 *
 *     PTP enabled and MPS packet, read HW timestamp
 */
static int t4_rx_hststamp(struct adapter *adapter, const __be64 *rsp,
                          struct sge_eth_rxq *rxq, struct sk_buff *skb)
{
        int ret;

        if (unlikely((*(u8 *)rsp == CPL_RX_MPS_PKT) &&
                     !is_t4(adapter->params.chip))) {
                ret = t4_systim_to_hwstamp(adapter, skb);
                if (ret == RX_PTP_PKT_ERR) {
                        kfree_skb(skb);
                        rxq->stats.rx_drops++;
                }
                return ret;
        }
        return RX_NON_PTP_PKT;
}

/**
 *      t4_tx_hststamp - Loopback PTP Transmit Event Message
 *      @adap: the adapter
 *      @skb: the packet
 *      @dev: the ingress net device
 *
 *      Read hardware timestamp for the loopback PTP Tx event message
 */
static int t4_tx_hststamp(struct adapter *adapter, struct sk_buff *skb,
                          struct net_device *dev)
{
        struct port_info *pi = netdev_priv(dev);

        if (!is_t4(adapter->params.chip) && adapter->ptp_tx_skb) {
                cxgb4_ptp_read_hwstamp(adapter, pi);
                kfree_skb(skb);
                return 0;
        }
        return 1;
}

/**
 *      t4_tx_completion_handler - handle CPL_SGE_EGR_UPDATE messages
 *      @rspq: Ethernet RX Response Queue associated with Ethernet TX Queue
 *      @rsp: Response Entry pointer into Response Queue
 *      @gl: Gather List pointer
 *
 *      For adapters which support the SGE Doorbell Queue Timer facility,
 *      we configure the Ethernet TX Queues to send CIDX Updates to the
 *      Associated Ethernet RX Response Queue with CPL_SGE_EGR_UPDATE
 *      messages.  This adds a small load to PCIe Link RX bandwidth and,
 *      potentially, higher CPU Interrupt load, but allows us to respond
 *      much more quickly to the CIDX Updates.  This is important for
 *      Upper Layer Software which isn't willing to have a large amount
 *      of TX Data outstanding before receiving DMA Completions.
 */
static void t4_tx_completion_handler(struct sge_rspq *rspq,
                                     const __be64 *rsp,
                                     const struct pkt_gl *gl)
{
        u8 opcode = ((const struct rss_header *)rsp)->opcode;
        struct port_info *pi = netdev_priv(rspq->netdev);
        struct adapter *adapter = rspq->adap;
        struct sge *s = &adapter->sge;
        struct sge_eth_txq *txq;

        /* skip RSS header */
        rsp++;

        /* FW can send EGR_UPDATEs encapsulated in a CPL_FW4_MSG.
         */
        if (unlikely(opcode == CPL_FW4_MSG &&
                     ((const struct cpl_fw4_msg *)rsp)->type ==
                                                        FW_TYPE_RSSCPL)) {
                rsp++;
                opcode = ((const struct rss_header *)rsp)->opcode;
                rsp++;
        }

        if (unlikely(opcode != CPL_SGE_EGR_UPDATE)) {
                pr_info("%s: unexpected FW4/CPL %#x on Rx queue\n",
                        __func__, opcode);
                return;
        }

        txq = &s->ethtxq[pi->first_qset + rspq->idx];

        /* We've got the Hardware Consumer Index Update in the Egress Update
         * message.  If we're using the SGE Doorbell Queue Timer mechanism,
         * these Egress Update messages will be our sole CIDX Updates we get
         * since we don't want to chew up PCIe bandwidth for both Ingress
         * Messages and Status Page writes.  However, The code which manages
         * reclaiming successfully DMA'ed TX Work Requests uses the CIDX value
         * stored in the Status Page at the end of the TX Queue.  It's easiest
         * to simply copy the CIDX Update value from the Egress Update message
         * to the Status Page.  Also note that no Endian issues need to be
         * considered here since both are Big Endian and we're just copying
         * bytes consistently ...
         */
        if (txq->dbqt) {
                struct cpl_sge_egr_update *egr;

                egr = (struct cpl_sge_egr_update *)rsp;
                WRITE_ONCE(txq->q.stat->cidx, egr->cidx);
        }

        t4_sge_eth_txq_egress_update(adapter, txq, -1);
}

/**
 *      t4_ethrx_handler - process an ingress ethernet packet
 *      @q: the response queue that received the packet
 *      @rsp: the response queue descriptor holding the RX_PKT message
 *      @si: the gather list of packet fragments
 *
 *      Process an ingress ethernet packet and deliver it to the stack.
 */
int t4_ethrx_handler(struct sge_rspq *q, const __be64 *rsp,
                     const struct pkt_gl *si)
{
        bool csum_ok;
        struct sk_buff *skb;
        const struct cpl_rx_pkt *pkt;
        struct sge_eth_rxq *rxq = container_of(q, struct sge_eth_rxq, rspq);
        struct adapter *adapter = q->adap;
        struct sge *s = &q->adap->sge;
        int cpl_trace_pkt = is_t4(q->adap->params.chip) ?
                            CPL_TRACE_PKT : CPL_TRACE_PKT_T5;
        u16 err_vec, tnl_hdr_len = 0;
        struct port_info *pi;
        int ret = 0;

        /* If we're looking at TX Queue CIDX Update, handle that separately
         * and return.
         */
        if (unlikely((*(u8 *)rsp == CPL_FW4_MSG) ||
                     (*(u8 *)rsp == CPL_SGE_EGR_UPDATE))) {
                t4_tx_completion_handler(q, rsp, si);
                return 0;
        }

        if (unlikely(*(u8 *)rsp == cpl_trace_pkt))
                return handle_trace_pkt(q->adap, si);

        pkt = (const struct cpl_rx_pkt *)rsp;
        /* Compressed error vector is enabled for T6 only */
        if (q->adap->params.tp.rx_pkt_encap) {
                err_vec = T6_COMPR_RXERR_VEC_G(be16_to_cpu(pkt->err_vec));
                tnl_hdr_len = T6_RX_TNLHDR_LEN_G(ntohs(pkt->err_vec));
        } else {
                err_vec = be16_to_cpu(pkt->err_vec);
        }

        csum_ok = pkt->csum_calc && !err_vec &&
                  (q->netdev->features & NETIF_F_RXCSUM);

        if (err_vec)
                rxq->stats.bad_rx_pkts++;

        if (((pkt->l2info & htonl(RXF_TCP_F)) ||