RT-AC56 3.0.0.4.374.37 core

[tomato.git] / release / src-rt-6.x.4708 / linux / linux-2.6.36 / drivers / net / cxgb4 / sge.c

/*
 * This file is part of the Chelsio T4 Ethernet driver for Linux.
 *
 * Copyright (c) 2003-2010 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 <net/ipv6.h>
#include <net/tcp.h>
#include "cxgb4.h"
#include "t4_regs.h"
#include "t4_msg.h"
#include "t4fw_api.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

/* Ethernet header padding prepended to RX_PKTs */
#define RX_PKT_PAD 2

/*
 * 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.
 */
#define MAX_TX_RECLAIM 16

/*
 * 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)

/*
 * An FL with <= FL_STARVE_THRES buffers is starving and a periodic timer will
 * attempt to refill it.
 */
#define FL_STARVE_THRES 4

/*
 * Suspend an Ethernet Tx queue with fewer available descriptors than this.
 * This is the same as calc_tx_descs() for a TSO packet with
 * nr_frags == MAX_SKB_FRAGS.
 */
#define ETHTXQ_STOP_THRES \
        (1 + DIV_ROUND_UP((3 * MAX_SKB_FRAGS) / 2 + (MAX_SKB_FRAGS & 1), 8))

/*
 * 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 128

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

enum {
        /* packet alignment in FL buffers */
        FL_ALIGN = L1_CACHE_BYTES < 32 ? 32 : L1_CACHE_BYTES,
        /* egress status entry size */
        STAT_LEN = L1_CACHE_BYTES > 64 ? 128 : 64
};

struct tx_sw_desc {                /* SW state per Tx descriptor */
        struct sk_buff *skb;
        struct ulptx_sgl *sgl;
};

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

/*
 * The low bits of rx_sw_desc.dma_addr have special meaning.
 */
enum {
        RX_LARGE_BUF    = 1 << 0, /* buffer is larger than PAGE_SIZE */
        RX_UNMAPPED_BUF = 1 << 1, /* buffer is not mapped */
};

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

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 */
}

static inline bool fl_starving(const struct sge_fl *fl)
{
        return fl->avail - fl->pend_cred <= FL_STARVE_THRES;
}

static int 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 = dma_map_page(dev, fp->page, fp->page_offset, fp->size,
                                       DMA_TO_DEVICE);
                if (dma_mapping_error(dev, *addr))
                        goto unwind;
        }
        return 0;

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

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

#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++, fp->size, 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.
 */
static 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);
                        kfree_skb(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(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
 *      @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.
 */
static inline void reclaim_completed_tx(struct adapter *adap, struct sge_txq *q,
                                        bool unmap)
{
        int avail = reclaimable(q);

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

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

static inline int get_buf_size(const struct rx_sw_desc *d)
{
#if FL_PG_ORDER > 0
        return (d->dma_addr & RX_LARGE_BUF) ? (PAGE_SIZE << FL_PG_ORDER) :
                                              PAGE_SIZE;
#else
        return PAGE_SIZE;
#endif
}

/**
 *      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(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(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) {
                wmb();
                t4_write_reg(adap, MYPF_REG(SGE_PF_KDOORBELL), DBPRIO |
                             QID(q->cntxt_id) | PIDX(q->pend_cred / 8));
                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 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];

        gfp |= __GFP_NOWARN;         /* failures are expected */

#if FL_PG_ORDER > 0
        /*
         * Prefer large buffers
         */
        while (n) {
                pg = alloc_pages(gfp | __GFP_COMP, 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 << FL_PG_ORDER,
                                       PCI_DMA_FROMDEVICE);
                if (unlikely(dma_mapping_error(adap->pdev_dev, mapping))) {
                        __free_pages(pg, FL_PG_ORDER);
                        goto out;   /* do not try small pages for this error */
                }
                mapping |= RX_LARGE_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--;
        }
#endif

        while (n--) {
                pg = __netdev_alloc_page(adap->port[0], gfp);
                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))) {
                        netdev_free_page(adap->port[0], pg);
                        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(q))) {
                smp_wmb();
                set_bit(q->cntxt_id, 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
 *
 *      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)
{
        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(nelem, sw_size, GFP_KERNEL);

                if (!s) {
                        dma_free_coherent(dev, len, p, *phys);
                        return NULL;
                }
        }
        if (metadata)
                *(void **)metadata = s;
        memset(p, 0, len);
        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)
{
        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.
 */
static inline int is_eth_imm(const struct sk_buff *skb)
{
        return skb->len <= MAX_IMM_TX_PKT_LEN - sizeof(struct cpl_tx_pkt);
}

/**
 *      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 flits;

        if (is_eth_imm(skb))
                return DIV_ROUND_UP(skb->len + sizeof(struct cpl_tx_pkt), 8);

        flits = sgl_len(skb_shinfo(skb)->nr_frags + 1) + 4;
        if (skb_shinfo(skb)->gso_size)
                flits += 2;
        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)
{
        return flits_to_desc(calc_tx_flits(skb));
}

/**
 *      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.
 */
static void 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(si->frags[0].size);
                sgl->addr0 = cpu_to_be64(addr[1]);
        }

        sgl->cmd_nsge = htonl(ULPTX_CMD(ULP_TX_SC_DSGL) | ULPTX_NSGE(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(si->frags[i].size);
                to->len[1] = cpu_to_be32(si->frags[++i].size);
                to->addr[0] = cpu_to_be64(addr[i]);
                to->addr[1] = cpu_to_be64(addr[++i]);
        }
        if (nfrags) {
                to->len[0] = cpu_to_be32(si->frags[i].size);
                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 */
                *(u64 *)end = 0;
}

/**
 *      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.
 */
static inline void ring_tx_db(struct adapter *adap, struct sge_txq *q, int n)
{
        wmb();            /* write descriptors before telling HW */
        t4_write_reg(adap, MYPF_REG(SGE_PF_KDOORBELL),
                     QID(q->cntxt_id) | PIDX(n));
}

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

        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;
}

/*
 * Figure out what HW csum a packet wants and return the appropriate control
 * bits.
 */
static u64 hwcsum(const struct sk_buff *skb)
{
        int csum_type;
        const struct iphdr *iph = ip_hdr(skb);

        if (iph->version == 4) {
                if (iph->protocol == IPPROTO_TCP)
                        csum_type = TX_CSUM_TCPIP;
                else if (iph->protocol == 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;
                }
        } else {
                /*
                 * this doesn't work with extension headers
                 */
                const struct ipv6hdr *ip6h = (const struct ipv6hdr *)iph;

                if (ip6h->nexthdr == IPPROTO_TCP)
                        csum_type = TX_CSUM_TCPIP6;
                else if (ip6h->nexthdr == IPPROTO_UDP)
                        csum_type = TX_CSUM_UDPIP6;
                else
                        goto nocsum;
        }

        if (likely(csum_type >= TX_CSUM_TCPIP))
                return TXPKT_CSUM_TYPE(csum_type) |
                        TXPKT_IPHDR_LEN(skb_network_header_len(skb)) |
                        TXPKT_ETHHDR_LEN(skb_network_offset(skb) - ETH_HLEN);
        else {
                int start = skb_transport_offset(skb);

                return TXPKT_CSUM_TYPE(csum_type) | TXPKT_CSUM_START(start) |
                        TXPKT_CSUM_LOC(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;
}

/**
 *      t4_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.
 */
netdev_tx_t t4_eth_xmit(struct sk_buff *skb, struct net_device *dev)
{
        u32 wr_mid;
        u64 cntrl, *end;
        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];

        /*
         * 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(skb);
                return NETDEV_TX_OK;
        }

        pi = netdev_priv(dev);
        adap = pi->adapter;
        qidx = skb_get_queue_mapping(skb);
        q = &adap->sge.ethtxq[qidx + pi->first_qset];

        reclaim_completed_tx(adap, &q->q, true);

        flits = calc_tx_flits(skb);
        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);
                return NETDEV_TX_BUSY;
        }

        if (!is_eth_imm(skb) &&
            unlikely(map_skb(adap->pdev_dev, skb, addr) < 0)) {
                q->mapping_err++;
                goto out_free;
        }

        wr_mid = FW_WR_LEN16(DIV_ROUND_UP(flits, 2));
        if (unlikely(credits < ETHTXQ_STOP_THRES)) {
                eth_txq_stop(q);
                wr_mid |= FW_WR_EQUEQ | FW_WR_EQUIQ;
        }

        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;

        ssi = skb_shinfo(skb);
        if (ssi->gso_size) {
                struct cpl_tx_pkt_lso *lso = (void *)wr;
                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 = htonl(FW_WR_OP(FW_ETH_TX_PKT_WR) |
                                       FW_WR_IMMDLEN(sizeof(*lso)));
                lso->c.lso_ctrl = htonl(LSO_OPCODE(CPL_TX_PKT_LSO) |
                                        LSO_FIRST_SLICE | LSO_LAST_SLICE |
                                        LSO_IPV6(v6) |
                                        LSO_ETHHDR_LEN(eth_xtra_len / 4) |
                                        LSO_IPHDR_LEN(l3hdr_len / 4) |
                                        LSO_TCPHDR_LEN(tcp_hdr(skb)->doff));
                lso->c.ipid_ofst = htons(0);
                lso->c.mss = htons(ssi->gso_size);
                lso->c.seqno_offset = htonl(0);
                lso->c.len = htonl(skb->len);
                cpl = (void *)(lso + 1);
                cntrl = TXPKT_CSUM_TYPE(v6 ? TX_CSUM_TCPIP6 : TX_CSUM_TCPIP) |
                        TXPKT_IPHDR_LEN(l3hdr_len) |
                        TXPKT_ETHHDR_LEN(eth_xtra_len);
                q->tso++;
                q->tx_cso += ssi->gso_segs;
        } else {
                int len;

                len = is_eth_imm(skb) ? skb->len + sizeof(*cpl) : sizeof(*cpl);
                wr->op_immdlen = htonl(FW_WR_OP(FW_ETH_TX_PKT_WR) |
                                       FW_WR_IMMDLEN(len));
                cpl = (void *)(wr + 1);
                if (skb->ip_summed == CHECKSUM_PARTIAL) {
                        cntrl = hwcsum(skb) | TXPKT_IPCSUM_DIS;
                        q->tx_cso++;
                } else
                        cntrl = TXPKT_L4CSUM_DIS | TXPKT_IPCSUM_DIS;
        }

        if (vlan_tx_tag_present(skb)) {
                q->vlan_ins++;
                cntrl |= TXPKT_VLAN_VLD | TXPKT_VLAN(vlan_tx_tag_get(skb));
        }

        cpl->ctrl0 = htonl(TXPKT_OPCODE(CPL_TX_PKT_XT) |
                           TXPKT_INTF(pi->tx_chan) | TXPKT_PF(0));
        cpl->pack = htons(0);
        cpl->len = htons(skb->len);
        cpl->ctrl1 = cpu_to_be64(cntrl);

        if (is_eth_imm(skb)) {
                inline_tx_skb(skb, &q->q, cpl + 1);
                dev_kfree_skb(skb);
        } else {
                int last_desc;

                write_sgl(skb, &q->q, (struct ulptx_sgl *)(cpl + 1), 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 *)(cpl + 1);
        }

        txq_advance(&q->q, ndesc);

        ring_tx_db(adap, &q->q, ndesc);
        return NETDEV_TX_OK;
}

/**
 *      reclaim_completed_tx_imm - reclaim completed control-queue Tx descs
 *      @q: the SGE control Tx queue
 *
 *      This is a variant of 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(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 | FW_WR_EQUIQ);
                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];
        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);

        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 */

                /*
                 * Write descriptors and free skbs outside the lock to limit
                 * wait times.  q->full is still set so new skbs will be queued.
                 */
                spin_unlock(&q->sendq.lock);

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

                written += ndesc;
                txq_advance(&q->q, ndesc);
                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) {
                        ring_tx_db(q->adap, &q->q, written);
                        written = 0;
                }
                spin_lock(&q->sendq.lock);
        }
        q->full = 0;
ringdb: if (written)
                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)
{
        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 != skb->transport_header)
                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_ofld_txq *q)
{
        q->mapping_err++;
        q->q.stops++;
        set_bit(q->q.cntxt_id, q->adap->sge.txq_maperr);
}

/**
 *      ofldtxq_stop - stop an offload Tx queue that has become full
 *      @q: the queue to stop
 *      @skb: the packet 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_ofld_txq *q, struct sk_buff *skb)
{
        struct fw_wr_hdr *wr = (struct fw_wr_hdr *)skb->data;

        wr->lo |= htonl(FW_WR_EQUEQ | FW_WR_EQUIQ);
        q->q.stops++;
        q->full = 1;
}

/**
 *      service_ofldq - restart a suspended offload queue
 *      @q: the offload queue
 *
 *      Services an offload Tx queue by moving packets from its packet queue
 *      to the HW Tx ring.  The function starts and ends with the queue locked.
 */
static void service_ofldq(struct sge_ofld_txq *q)
{
        u64 *pos;
        int credits;
        struct sk_buff *skb;
        unsigned int written = 0;
        unsigned int flits, ndesc;

        while ((skb = skb_peek(&q->sendq)) != NULL && !q->full) {
                /*
                 * We drop the lock but leave skb on sendq, thus retaining
                 * exclusive access to the state of the queue.
                 */
                spin_unlock(&q->sendq.lock);

                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, skb);

                pos = (u64 *)&q->q.desc[q->q.pidx];
                if (is_ofld_imm(skb))
                        inline_tx_skb(skb, &q->q, pos);
                else if (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);

                        memcpy(pos, skb->data, hdr_len);
                        write_sgl(skb, &q->q, (void *)pos + hdr_len,
                                  pos + flits, 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)) {
                        ring_tx_db(q->adap, &q->q, written);
                        written = 0;
                }

                spin_lock(&q->sendq.lock);
                __skb_unlink(skb, &q->sendq);
                if (is_ofld_imm(skb))
                        kfree_skb(skb);
        }
        if (likely(written))
                ring_tx_db(q->adap, &q->q, written);
}

/**
 *      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_ofld_txq *q, struct sk_buff *skb)
{
        skb->priority = calc_tx_flits_ofld(skb);       /* save for restart */
        spin_lock(&q->sendq.lock);
        __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_ofld_txq *q = (struct sge_ofld_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 ofld_send(struct adapter *adap, struct sk_buff *skb)
{
        unsigned int idx = skb_txq(skb);

        if (unlikely(is_ctrl_pkt(skb)))
                return ctrl_xmit(&adap->sge.ctrlq[idx], skb);
        return ofld_xmit(&adap->sge.ofldtxq[idx], 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 = ofld_send(adap, skb);
        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 inline void copy_frags(struct skb_shared_info *ssi,
                              const struct pkt_gl *gl, unsigned int offset)
{
        unsigned int n;

        /* usually there's just one frag */
        ssi->frags[0].page = gl->frags[0].page;
        ssi->frags[0].page_offset = gl->frags[0].page_offset + offset;
        ssi->frags[0].size = gl->frags[0].size - offset;
        ssi->nr_frags = gl->nfrags;
        n = gl->nfrags - 1;
        if (n)
                memcpy(&ssi->frags[1], &gl->frags[1], n * sizeof(skb_frag_t));

        /* get a reference to the last page, we don't own it */
        get_page(gl->frags[n].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_shinfo(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 skb_frag_t *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;
        struct cpl_trace_pkt *p;

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

        p = (struct cpl_trace_pkt *)skb->data;
        __skb_pull(skb, sizeof(*p));
        skb_reset_mac_header(skb);
        skb->protocol = htons(0xffff);
        skb->dev = adap->port[0];
        netif_receive_skb(skb);
        return 0;
}

static void do_gro(struct sge_eth_rxq *rxq, const struct pkt_gl *gl,
                   const struct cpl_rx_pkt *pkt)
{
        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_shinfo(skb), gl, RX_PKT_PAD);
        skb->len = gl->tot_len - RX_PKT_PAD;
        skb->data_len = skb->len;
        skb->truesize += skb->data_len;
        skb->ip_summed = CHECKSUM_UNNECESSARY;
        skb_record_rx_queue(skb, rxq->rspq.idx);
        if (rxq->rspq.netdev->features & NETIF_F_RXHASH)
                skb->rxhash = (__force u32)pkt->rsshdr.hash_val;

        if (unlikely(pkt->vlan_ex)) {
                struct port_info *pi = netdev_priv(rxq->rspq.netdev);
                struct vlan_group *grp = pi->vlan_grp;

                rxq->stats.vlan_ex++;
                if (likely(grp)) {
                        ret = vlan_gro_frags(&rxq->rspq.napi, grp,
                                             ntohs(pkt->vlan));
                        goto stats;
                }
        }
        ret = napi_gro_frags(&rxq->rspq.napi);
stats:  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++;
}

/**
 *      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;
        struct port_info *pi;
        const struct cpl_rx_pkt *pkt;
        struct sge_eth_rxq *rxq = container_of(q, struct sge_eth_rxq, rspq);

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

        pkt = (const struct cpl_rx_pkt *)rsp;
        csum_ok = pkt->csum_calc && !pkt->err_vec;
        if ((pkt->l2info & htonl(RXF_TCP)) &&
            (q->netdev->features & NETIF_F_GRO) && csum_ok && !pkt->ip_frag) {
                do_gro(rxq, si, pkt);
                return 0;
        }

        skb = cxgb4_pktgl_to_skb(si, RX_PKT_SKB_LEN, RX_PULL_LEN);
        if (unlikely(!skb)) {
                t4_pktgl_free(si);
                rxq->stats.rx_drops++;
                return 0;
        }

        __skb_pull(skb, RX_PKT_PAD);      /* remove ethernet header padding */
        skb->protocol = eth_type_trans(skb, q->netdev);
        skb_record_rx_queue(skb, q->idx);
        if (skb->dev->features & NETIF_F_RXHASH)
                skb->rxhash = (__force u32)pkt->rsshdr.hash_val;

        pi = netdev_priv(skb->dev);
        rxq->stats.pkts++;

        if (csum_ok && (pi->rx_offload & RX_CSO) &&
            (pkt->l2info & htonl(RXF_UDP | RXF_TCP))) {
                if (!pkt->ip_frag) {
                        skb->ip_summed = CHECKSUM_UNNECESSARY;
                        rxq->stats.rx_cso++;
                } else if (pkt->l2info & htonl(RXF_IP)) {
                        __sum16 c = (__force __sum16)pkt->csum;
                        skb->csum = csum_unfold(c);
                        skb->ip_summed = CHECKSUM_COMPLETE;
                        rxq->stats.rx_cso++;
                }
        } else
                skb->ip_summed = CHECKSUM_NONE;

        if (unlikely(pkt->vlan_ex)) {
                struct vlan_group *grp = pi->vlan_grp;

                rxq->stats.vlan_ex++;
                if (likely(grp))
                        vlan_hwaccel_receive_skb(skb, grp, ntohs(pkt->vlan));
                else
                        dev_kfree_skb_any(skb);
        } else
                netif_receive_skb(skb);

        return 0;
}

/**
 *      restore_rx_bufs - put back a packet's Rx buffers
 *      @si: the packet gather list
 *      @q: the SGE free list
 *      @frags: number of FL buffers to restore
 *
 *      Puts back on an FL the Rx buffers associated with @si.  The buffers
 *      have already been unmapped and are left unmapped, we mark them so to
 *      prevent further unmapping attempts.
 *
 *      This function undoes a series of @unmap_rx_buf calls when we find out
 *      that the current packet can't be processed right away afterall and we
 *      need to come back to it later.  This is a very rare event and there's
 *      no effort to make this particularly efficient.
 */
static void restore_rx_bufs(const struct pkt_gl *si, struct sge_fl *q,
                            int frags)
{
        struct rx_sw_desc *d;

        while (frags--) {
                if (q->cidx == 0)
                        q->cidx = q->size - 1;
                else
                        q->cidx--;
                d = &q->sdesc[q->cidx];
                d->page = si->frags[frags].page;
                d->dma_addr |= RX_UNMAPPED_BUF;
                q->avail++;
        }
}

/**
 *      is_new_response - check if a response is newly written
 *      @r: the response descriptor
 *      @q: the response queue
 *
 *      Returns true if a response descriptor contains a yet unprocessed
 *      response.
 */
static inline bool is_new_response(const struct rsp_ctrl *r,
                                   const struct sge_rspq *q)
{
        return RSPD_GEN(r->type_gen) == q->gen;
}

/**
 *      rspq_next - advance to the next entry in a response queue
 *      @q: the queue
 *
 *      Updates the state of a response queue to advance it to the next entry.
 */
static inline void rspq_next(struct sge_rspq *q)
{
        q->cur_desc = (void *)q->cur_desc + q->iqe_len;
        if (unlikely(++q->cidx == q->size)) {
                q->cidx = 0;
                q->gen ^= 1;
                q->cur_desc = q->desc;
        }
}

/**
 *      process_responses - process responses from an SGE response queue
 *      @q: the ingress queue to process
 *      @budget: how many responses can be processed in this round
 *
 *      Process responses from an SGE response queue up to the supplied budget.
 *      Responses include received packets as well as control messages from FW
 *      or HW.
 *
 *      Additionally choose the interrupt holdoff time for the next interrupt
 *      on this queue.  If the system is under memory shortage use a fairly
 *      long delay to help recovery.
 */
static int process_responses(struct sge_rspq *q, int budget)
{
        int ret, rsp_type;
        int budget_left = budget;
        const struct rsp_ctrl *rc;
        struct sge_eth_rxq *rxq = container_of(q, struct sge_eth_rxq, rspq);

        while (likely(budget_left)) {
                rc = (void *)q->cur_desc + (q->iqe_len - sizeof(*rc));
                if (!is_new_response(rc, q))
                        break;

                rmb();
                rsp_type = RSPD_TYPE(rc->type_gen);
                if (likely(rsp_type == RSP_TYPE_FLBUF)) {
                        skb_frag_t *fp;
                        struct pkt_gl si;
                        const struct rx_sw_desc *rsd;
                        u32 len = ntohl(rc->pldbuflen_qid), bufsz, frags;

                        if (len & RSPD_NEWBUF) {
                                if (likely(q->offset > 0)) {
                                        free_rx_bufs(q->adap, &rxq->fl, 1);
                                        q->offset = 0;
                                }
                                len = RSPD_LEN(len);
                        }
                        si.tot_len = len;

                        /* gather packet fragments */
                        for (frags = 0, fp = si.frags; ; frags++, fp++) {
                                rsd = &rxq->fl.sdesc[rxq->fl.cidx];
                                bufsz = get_buf_size(rsd);
                                fp->page = rsd->page;
                                fp->page_offset = q->offset;
                                fp->size = min(bufsz, len);
                                len -= fp->size;
                                if (!len)
                                        break;
                                unmap_rx_buf(q->adap, &rxq->fl);
                        }

                        /*
                         * Last buffer remains mapped so explicitly make it
                         * coherent for CPU access.
                         */
                        dma_sync_single_for_cpu(q->adap->pdev_dev,
                                                get_buf_addr(rsd),
                                                fp->size, DMA_FROM_DEVICE);

                        si.va = page_address(si.frags[0].page) +
                                si.frags[0].page_offset;
                        prefetch(si.va);

                        si.nfrags = frags + 1;
                        ret = q->handler(q, q->cur_desc, &si);
                        if (likely(ret == 0))
                                q->offset += ALIGN(fp->size, FL_ALIGN);
                        else
                                restore_rx_bufs(&si, &rxq->fl, frags);
                } else if (likely(rsp_type == RSP_TYPE_CPL)) {
                        ret = q->handler(q, q->cur_desc, NULL);
                } else {
                        ret = q->handler(q, (const __be64 *)rc, CXGB4_MSG_AN);
                }

                if (unlikely(ret)) {
                        /* couldn't process descriptor, back off for recovery */
                        q->next_intr_params = QINTR_TIMER_IDX(NOMEM_TMR_IDX);
                        break;
                }

                rspq_next(q);
                budget_left--;
        }

        if (q->offset >= 0 && rxq->fl.size - rxq->fl.avail >= 16)
                __refill_fl(q->adap, &rxq->fl);
        return budget - budget_left;
}

/**
 *      napi_rx_handler - the NAPI handler for Rx processing
 *      @napi: the napi instance
 *      @budget: how many packets we can process in this round
 *
 *      Handler for new data events when using NAPI.  This does not need any
 *      locking or protection from interrupts as data interrupts are off at
 *      this point and other adapter interrupts do not interfere (the latter
 *      in not a concern at all with MSI-X as non-data interrupts then have
 *      a separate handler).
 */
static int napi_rx_handler(struct napi_struct *napi, int budget)
{
        unsigned int params;
        struct sge_rspq *q = container_of(napi, struct sge_rspq, napi);
        int work_done = process_responses(q, budget);

        if (likely(work_done < budget)) {
                napi_complete(napi);
                params = q->next_intr_params;
                q->next_intr_params = q->intr_params;
        } else
                params = QINTR_TIMER_IDX(7);

        t4_write_reg(q->adap, MYPF_REG(SGE_PF_GTS), CIDXINC(work_done) |
                     INGRESSQID((u32)q->cntxt_id) | SEINTARM(params));
        return work_done;
}

/*
 * The MSI-X interrupt handler for an SGE response queue.
 */
irqreturn_t t4_sge_intr_msix(int irq, void *cookie)
{
        struct sge_rspq *q = cookie;

        napi_schedule(&q->napi);
        return IRQ_HANDLED;
}

/*
 * Process the indirect interrupt entries in the interrupt queue and kick off
 * NAPI for each queue that has generated an entry.
 */
static unsigned int process_intrq(struct adapter *adap)
{
        unsigned int credits;
        const struct rsp_ctrl *rc;
        struct sge_rspq *q = &adap->sge.intrq;

        spin_lock(&adap->sge.intrq_lock);
        for (credits = 0; ; credits++) {
                rc = (void *)q->cur_desc + (q->iqe_len - sizeof(*rc));
                if (!is_new_response(rc, q))
                        break;

                rmb();
                if (RSPD_TYPE(rc->type_gen) == RSP_TYPE_INTR) {
                        unsigned int qid = ntohl(rc->pldbuflen_qid);

                        napi_schedule(&adap->sge.ingr_map[qid]->napi);
                }

                rspq_next(q);
        }

        t4_write_reg(adap, MYPF_REG(SGE_PF_GTS), CIDXINC(credits) |
                     INGRESSQID(q->cntxt_id) | SEINTARM(q->intr_params));
        spin_unlock(&adap->sge.intrq_lock);
        return credits;
}

/*
 * The MSI interrupt handler, which handles data events from SGE response queues
 * as well as error and other async events as they all use the same MSI vector.
 */
static irqreturn_t t4_intr_msi(int irq, void *cookie)
{
        struct adapter *adap = cookie;

        t4_slow_intr_handler(adap);
        process_intrq(adap);
        return IRQ_HANDLED;
}

/*
 * Interrupt handler for legacy INTx interrupts.
 * Handles data events from SGE response queues as well as error and other
 * async events as they all use the same interrupt line.
 */
static irqreturn_t t4_intr_intx(int irq, void *cookie)
{
        struct adapter *adap = cookie;

        t4_write_reg(adap, MYPF_REG(PCIE_PF_CLI), 0);
        if (t4_slow_intr_handler(adap) | process_intrq(adap))
                return IRQ_HANDLED;
        return IRQ_NONE;             /* probably shared interrupt */
}

/**
 *      t4_intr_handler - select the top-level interrupt handler
 *      @adap: the adapter
 *
 *      Selects the top-level interrupt handler based on the type of interrupts
 *      (MSI-X, MSI, or INTx).
 */
irq_handler_t t4_intr_handler(struct adapter *adap)
{
        if (adap->flags & USING_MSIX)
                return t4_sge_intr_msix;
        if (adap->flags & USING_MSI)
                return t4_intr_msi;
        return t4_intr_intx;
}

static void sge_rx_timer_cb(unsigned long data)
{
        unsigned long m;
        unsigned int i, cnt[2];
        struct adapter *adap = (struct adapter *)data;
        struct sge *s = &adap->sge;

        for (i = 0; i < ARRAY_SIZE(s->starving_fl); i++)
                for (m = s->starving_fl[i]; m; m &= m - 1) {
                        struct sge_eth_rxq *rxq;
                        unsigned int id = __ffs(m) + i * BITS_PER_LONG;
                        struct sge_fl *fl = s->egr_map[id];

                        clear_bit(id, s->starving_fl);
                        smp_mb__after_clear_bit();

                        if (fl_starving(fl)) {
                                rxq = container_of(fl, struct sge_eth_rxq, fl);
                                if (napi_reschedule(&rxq->rspq.napi))
                                        fl->starving++;
                                else
                                        set_bit(id, s->starving_fl);
                        }
                }

        t4_write_reg(adap, SGE_DEBUG_INDEX, 13);
        cnt[0] = t4_read_reg(adap, SGE_DEBUG_DATA_HIGH);
        cnt[1] = t4_read_reg(adap, SGE_DEBUG_DATA_LOW);

        for (i = 0; i < 2; i++)
                if (cnt[i] >= s->starve_thres) {
                        if (s->idma_state[i] || cnt[i] == 0xffffffff)
                                continue;
                        s->idma_state[i] = 1;
                        t4_write_reg(adap, SGE_DEBUG_INDEX, 11);
                        m = t4_read_reg(adap, SGE_DEBUG_DATA_LOW) >> (i * 16);
                        dev_warn(adap->pdev_dev,
                                 "SGE idma%u starvation detected for "
                                 "queue %lu\n", i, m & 0xffff);
                } else if (s->idma_state[i])
                        s->idma_state[i] = 0;

        mod_timer(&s->rx_timer, jiffies + RX_QCHECK_PERIOD);
}

static void sge_tx_timer_cb(unsigned long data)
{
        unsigned long m;
        unsigned int i, budget;
        struct adapter *adap = (struct adapter *)data;
        struct sge *s = &adap->sge;

        for (i = 0; i < ARRAY_SIZE(s->txq_maperr); i++)
                for (m = s->txq_maperr[i]; m; m &= m - 1) {
                        unsigned long id = __ffs(m) + i * BITS_PER_LONG;
                        struct sge_ofld_txq *txq = s->egr_map[id];

                        clear_bit(id, s->txq_maperr);
                        tasklet_schedule(&txq->qresume_tsk);
                }

        budget = MAX_TIMER_TX_RECLAIM;
        i = s->ethtxq_rover;
        do {
                struct sge_eth_txq *q = &s->ethtxq[i];

                if (q->q.in_use &&
                    time_after_eq(jiffies, q->txq->trans_start + HZ / 100) &&
                    __netif_tx_trylock(q->txq)) {
                        int avail = reclaimable(&q->q);

                        if (avail) {
                                if (avail > budget)
                                        avail = budget;

                                free_tx_desc(adap, &q->q, avail, true);
                                q->q.in_use -= avail;
                                budget -= avail;
                        }
                        __netif_tx_unlock(q->txq);
                }

                if (++i >= s->ethqsets)
                        i = 0;
        } while (budget && i != s->ethtxq_rover);
        s->ethtxq_rover = i;
        mod_timer(&s->tx_timer, jiffies + (budget ? TX_QCHECK_PERIOD : 2));
}

int t4_sge_alloc_rxq(struct adapter *adap, struct sge_rspq *iq, bool fwevtq,
                     struct net_device *dev, int intr_idx,
                     struct sge_fl *fl, rspq_handler_t hnd)
{
        int ret, flsz = 0;
        struct fw_iq_cmd c;
        struct port_info *pi = netdev_priv(dev);

        /* Size needs to be multiple of 16, including status entry. */
        iq->size = roundup(iq->size, 16);

        iq->desc = alloc_ring(adap->pdev_dev, iq->size, iq->iqe_len, 0,
                              &iq->phys_addr, NULL, 0);
        if (!iq->desc)
                return -ENOMEM;

        memset(&c, 0, sizeof(c));
        c.op_to_vfn = htonl(FW_CMD_OP(FW_IQ_CMD) | FW_CMD_REQUEST |
                            FW_CMD_WRITE | FW_CMD_EXEC |
                            FW_IQ_CMD_PFN(adap->fn) | FW_IQ_CMD_VFN(0));
        c.alloc_to_len16 = htonl(FW_IQ_CMD_ALLOC | FW_IQ_CMD_IQSTART(1) |
                                 FW_LEN16(c));
        c.type_to_iqandstindex = htonl(FW_IQ_CMD_TYPE(FW_IQ_TYPE_FL_INT_CAP) |
                FW_IQ_CMD_IQASYNCH(fwevtq) | FW_IQ_CMD_VIID(pi->viid) |
                FW_IQ_CMD_IQANDST(intr_idx < 0) | FW_IQ_CMD_IQANUD(1) |
                FW_IQ_CMD_IQANDSTINDEX(intr_idx >= 0 ? intr_idx :
                                                        -intr_idx - 1));
        c.iqdroprss_to_iqesize = htons(FW_IQ_CMD_IQPCIECH(pi->tx_chan) |
                FW_IQ_CMD_IQGTSMODE |
                FW_IQ_CMD_IQINTCNTTHRESH(iq->pktcnt_idx) |
                FW_IQ_CMD_IQESIZE(ilog2(iq->iqe_len) - 4));
        c.iqsize = htons(iq->size);
        c.iqaddr = cpu_to_be64(iq->phys_addr);

        if (fl) {
                fl->size = roundup(fl->size, 8);
                fl->desc = alloc_ring(adap->pdev_dev, fl->size, sizeof(__be64),
                                      sizeof(struct rx_sw_desc), &fl->addr,
                                      &fl->sdesc, STAT_LEN);
                if (!fl->desc)
                        goto fl_nomem;

                flsz = fl->size / 8 + STAT_LEN / sizeof(struct tx_desc);
                c.iqns_to_fl0congen = htonl(FW_IQ_CMD_FL0PACKEN |
                                            FW_IQ_CMD_FL0PADEN);
                c.fl0dcaen_to_fl0cidxfthresh = htons(FW_IQ_CMD_FL0FBMIN(2) |
                                FW_IQ_CMD_FL0FBMAX(3));
                c.fl0size = htons(flsz);
                c.fl0addr = cpu_to_be64(fl->addr);
        }

        ret = t4_wr_mbox(adap, adap->fn, &c, sizeof(c), &c);
        if (ret)
                goto err;

        netif_napi_add(dev, &iq->napi, napi_rx_handler, 64);
        iq->cur_desc = iq->desc;
        iq->cidx = 0;
        iq->gen = 1;
        iq->next_intr_params = iq->intr_params;
        iq->cntxt_id = ntohs(c.iqid);
        iq->abs_id = ntohs(c.physiqid);
        iq->size--;                           /* subtract status entry */
        iq->adap = adap;
        iq->netdev = dev;
        iq->handler = hnd;

        /* set offset to -1 to distinguish ingress queues without FL */
        iq->offset = fl ? 0 : -1;

        adap->sge.ingr_map[iq->cntxt_id] = iq;

        if (fl) {
                fl->cntxt_id = ntohs(c.fl0id);
                fl->avail = fl->pend_cred = 0;
                fl->pidx = fl->cidx = 0;
                fl->alloc_failed = fl->large_alloc_failed = fl->starving = 0;
                adap->sge.egr_map[fl->cntxt_id] = fl;
                refill_fl(adap, fl, fl_cap(fl), GFP_KERNEL);
        }
        return 0;

fl_nomem:
        ret = -ENOMEM;
err:
        if (iq->desc) {
                dma_free_coherent(adap->pdev_dev, iq->size * iq->iqe_len,
                                  iq->desc, iq->phys_addr);
                iq->desc = NULL;
        }
        if (fl && fl->desc) {
                kfree(fl->sdesc);
                fl->sdesc = NULL;
                dma_free_coherent(adap->pdev_dev, flsz * sizeof(struct tx_desc),
                                  fl->desc, fl->addr);
                fl->desc = NULL;
        }
        return ret;
}

static void init_txq(struct adapter *adap, struct sge_txq *q, unsigned int id)
{
        q->in_use = 0;
        q->cidx = q->pidx = 0;
        q->stops = q->restarts = 0;
        q->stat = (void *)&q->desc[q->size];
        q->cntxt_id = id;
        adap->sge.egr_map[id] = q;
}

int t4_sge_alloc_eth_txq(struct adapter *adap, struct sge_eth_txq *txq,
                         struct net_device *dev, struct netdev_queue *netdevq,
                         unsigned int iqid)
{
        int ret, nentries;
        struct fw_eq_eth_cmd c;
        struct port_info *pi = netdev_priv(dev);

        /* Add status entries */
        nentries = txq->q.size + STAT_LEN / sizeof(struct tx_desc);

        txq->q.desc = alloc_ring(adap->pdev_dev, txq->q.size,
                        sizeof(struct tx_desc), sizeof(struct tx_sw_desc),
                        &txq->q.phys_addr, &txq->q.sdesc, STAT_LEN);
        if (!txq->q.desc)
                return -ENOMEM;

        memset(&c, 0, sizeof(c));
        c.op_to_vfn = htonl(FW_CMD_OP(FW_EQ_ETH_CMD) | FW_CMD_REQUEST |
                            FW_CMD_WRITE | FW_CMD_EXEC |
                            FW_EQ_ETH_CMD_PFN(adap->fn) | FW_EQ_ETH_CMD_VFN(0));
        c.alloc_to_len16 = htonl(FW_EQ_ETH_CMD_ALLOC |
                                 FW_EQ_ETH_CMD_EQSTART | FW_LEN16(c));
        c.viid_pkd = htonl(FW_EQ_ETH_CMD_VIID(pi->viid));
        c.fetchszm_to_iqid = htonl(FW_EQ_ETH_CMD_HOSTFCMODE(2) |
                                   FW_EQ_ETH_CMD_PCIECHN(pi->tx_chan) |
                                   FW_EQ_ETH_CMD_IQID(iqid));
        c.dcaen_to_eqsize = htonl(FW_EQ_ETH_CMD_FBMIN(2) |
                                  FW_EQ_ETH_CMD_FBMAX(3) |
                                  FW_EQ_ETH_CMD_CIDXFTHRESH(5) |
                                  FW_EQ_ETH_CMD_EQSIZE(nentries));
        c.eqaddr = cpu_to_be64(txq->q.phys_addr);

        ret = t4_wr_mbox(adap, adap->fn, &c, sizeof(c), &c);
        if (ret) {
                kfree(txq->q.sdesc);
                txq->q.sdesc = NULL;
                dma_free_coherent(adap->pdev_dev,
                                  nentries * sizeof(struct tx_desc),
                                  txq->q.desc, txq->q.phys_addr);
                txq->q.desc = NULL;
                return ret;
        }

        init_txq(adap, &txq->q, FW_EQ_ETH_CMD_EQID_GET(ntohl(c.eqid_pkd)));
        txq->txq = netdevq;
        txq->tso = txq->tx_cso = txq->vlan_ins = 0;
        txq->mapping_err = 0;
        return 0;
}

int t4_sge_alloc_ctrl_txq(struct adapter *adap, struct sge_ctrl_txq *txq,
                          struct net_device *dev, unsigned int iqid,
                          unsigned int cmplqid)
{
        int ret, nentries;
        struct fw_eq_ctrl_cmd c;
        struct port_info *pi = netdev_priv(dev);

        /* Add status entries */
        nentries = txq->q.size + STAT_LEN / sizeof(struct tx_desc);

        txq->q.desc = alloc_ring(adap->pdev_dev, nentries,
                                 sizeof(struct tx_desc), 0, &txq->q.phys_addr,
                                 NULL, 0);
        if (!txq->q.desc)
                return -ENOMEM;

        c.op_to_vfn = htonl(FW_CMD_OP(FW_EQ_CTRL_CMD) | FW_CMD_REQUEST |
                            FW_CMD_WRITE | FW_CMD_EXEC |
                            FW_EQ_CTRL_CMD_PFN(adap->fn) |
                            FW_EQ_CTRL_CMD_VFN(0));
        c.alloc_to_len16 = htonl(FW_EQ_CTRL_CMD_ALLOC |
                                 FW_EQ_CTRL_CMD_EQSTART | FW_LEN16(c));
        c.cmpliqid_eqid = htonl(FW_EQ_CTRL_CMD_CMPLIQID(cmplqid));
        c.physeqid_pkd = htonl(0);
        c.fetchszm_to_iqid = htonl(FW_EQ_CTRL_CMD_HOSTFCMODE(2) |
                                   FW_EQ_CTRL_CMD_PCIECHN(pi->tx_chan) |
                                   FW_EQ_CTRL_CMD_IQID(iqid));
        c.dcaen_to_eqsize = htonl(FW_EQ_CTRL_CMD_FBMIN(2) |
                                  FW_EQ_CTRL_CMD_FBMAX(3) |
                                  FW_EQ_CTRL_CMD_CIDXFTHRESH(5) |
                                  FW_EQ_CTRL_CMD_EQSIZE(nentries));
        c.eqaddr = cpu_to_be64(txq->q.phys_addr);

        ret = t4_wr_mbox(adap, adap->fn, &c, sizeof(c), &c);
        if (ret) {
                dma_free_coherent(adap->pdev_dev,
                                  nentries * sizeof(struct tx_desc),
                                  txq->q.desc, txq->q.phys_addr);
                txq->q.desc = NULL;
                return ret;
        }

        init_txq(adap, &txq->q, FW_EQ_CTRL_CMD_EQID_GET(ntohl(c.cmpliqid_eqid)));
        txq->adap = adap;
        skb_queue_head_init(&txq->sendq);
        tasklet_init(&txq->qresume_tsk, restart_ctrlq, (unsigned long)txq);
        txq->full = 0;
        return 0;
}

int t4_sge_alloc_ofld_txq(struct adapter *adap, struct sge_ofld_txq *txq,
                          struct net_device *dev, unsigned int iqid)
{
        int ret, nentries;
        struct fw_eq_ofld_cmd c;
        struct port_info *pi = netdev_priv(dev);

        /* Add status entries */
        nentries = txq->q.size + STAT_LEN / sizeof(struct tx_desc);

        txq->q.desc = alloc_ring(adap->pdev_dev, txq->q.size,
                        sizeof(struct tx_desc), sizeof(struct tx_sw_desc),
                        &txq->q.phys_addr, &txq->q.sdesc, STAT_LEN);
        if (!txq->q.desc)
                return -ENOMEM;

        memset(&c, 0, sizeof(c));
        c.op_to_vfn = htonl(FW_CMD_OP(FW_EQ_OFLD_CMD) | FW_CMD_REQUEST |
                            FW_CMD_WRITE | FW_CMD_EXEC |
                            FW_EQ_OFLD_CMD_PFN(adap->fn) |
                            FW_EQ_OFLD_CMD_VFN(0));
        c.alloc_to_len16 = htonl(FW_EQ_OFLD_CMD_ALLOC |
                                 FW_EQ_OFLD_CMD_EQSTART | FW_LEN16(c));
        c.fetchszm_to_iqid = htonl(FW_EQ_OFLD_CMD_HOSTFCMODE(2) |
                                   FW_EQ_OFLD_CMD_PCIECHN(pi->tx_chan) |
                                   FW_EQ_OFLD_CMD_IQID(iqid));
        c.dcaen_to_eqsize = htonl(FW_EQ_OFLD_CMD_FBMIN(2) |
                                  FW_EQ_OFLD_CMD_FBMAX(3) |
                                  FW_EQ_OFLD_CMD_CIDXFTHRESH(5) |
                                  FW_EQ_OFLD_CMD_EQSIZE(nentries));
        c.eqaddr = cpu_to_be64(txq->q.phys_addr);

        ret = t4_wr_mbox(adap, adap->fn, &c, sizeof(c), &c);
        if (ret) {
                kfree(txq->q.sdesc);
                txq->q.sdesc = NULL;
                dma_free_coherent(adap->pdev_dev,
                                  nentries * sizeof(struct tx_desc),
                                  txq->q.desc, txq->q.phys_addr);
                txq->q.desc = NULL;
                return ret;
        }

        init_txq(adap, &txq->q, FW_EQ_OFLD_CMD_EQID_GET(ntohl(c.eqid_pkd)));
        txq->adap = adap;
        skb_queue_head_init(&txq->sendq);
        tasklet_init(&txq->qresume_tsk, restart_ofldq, (unsigned long)txq);
        txq->full = 0;
        txq->mapping_err = 0;
        return 0;
}

static void free_txq(struct adapter *adap, struct sge_txq *q)
{
        dma_free_coherent(adap->pdev_dev,
                          q->size * sizeof(struct tx_desc) + STAT_LEN,
                          q->desc, q->phys_addr);
        q->cntxt_id = 0;
        q->sdesc = NULL;
        q->desc = NULL;
}

static void free_rspq_fl(struct adapter *adap, struct sge_rspq *rq,
                         struct sge_fl *fl)
{
        unsigned int fl_id = fl ? fl->cntxt_id : 0xffff;

        adap->sge.ingr_map[rq->cntxt_id] = NULL;
        t4_iq_free(adap, adap->fn, adap->fn, 0, FW_IQ_TYPE_FL_INT_CAP,
                   rq->cntxt_id, fl_id, 0xffff);
        dma_free_coherent(adap->pdev_dev, (rq->size + 1) * rq->iqe_len,
                          rq->desc, rq->phys_addr);
        netif_napi_del(&rq->napi);
        rq->netdev = NULL;
        rq->cntxt_id = rq->abs_id = 0;
        rq->desc = NULL;

        if (fl) {
                free_rx_bufs(adap, fl, fl->avail);
                dma_free_coherent(adap->pdev_dev, fl->size * 8 + STAT_LEN,
                                  fl->desc, fl->addr);
                kfree(fl->sdesc);
                fl->sdesc = NULL;
                fl->cntxt_id = 0;
                fl->desc = NULL;
        }
}

/**
 *      t4_free_sge_resources - free SGE resources
 *      @adap: the adapter
 *
 *      Frees resources used by the SGE queue sets.
 */
void t4_free_sge_resources(struct adapter *adap)
{
        int i;
        struct sge_eth_rxq *eq = adap->sge.ethrxq;
        struct sge_eth_txq *etq = adap->sge.ethtxq;
        struct sge_ofld_rxq *oq = adap->sge.ofldrxq;

        /* clean up Ethernet Tx/Rx queues */
        for (i = 0; i < adap->sge.ethqsets; i++, eq++, etq++) {
                if (eq->rspq.desc)
                        free_rspq_fl(adap, &eq->rspq, &eq->fl);
                if (etq->q.desc) {
                        t4_eth_eq_free(adap, adap->fn, adap->fn, 0,
                                       etq->q.cntxt_id);
                        free_tx_desc(adap, &etq->q, etq->q.in_use, true);
                        kfree(etq->q.sdesc);
                        free_txq(adap, &etq->q);
                }
        }

        /* clean up RDMA and iSCSI Rx queues */
        for (i = 0; i < adap->sge.ofldqsets; i++, oq++) {
                if (oq->rspq.desc)
                        free_rspq_fl(adap, &oq->rspq, &oq->fl);
        }
        for (i = 0, oq = adap->sge.rdmarxq; i < adap->sge.rdmaqs; i++, oq++) {
                if (oq->rspq.desc)
                        free_rspq_fl(adap, &oq->rspq, &oq->fl);
        }

        /* clean up offload Tx queues */
        for (i = 0; i < ARRAY_SIZE(adap->sge.ofldtxq); i++) {
                struct sge_ofld_txq *q = &adap->sge.ofldtxq[i];

                if (q->q.desc) {
                        tasklet_kill(&q->qresume_tsk);
                        t4_ofld_eq_free(adap, adap->fn, adap->fn, 0,
                                        q->q.cntxt_id);
                        free_tx_desc(adap, &q->q, q->q.in_use, false);
                        kfree(q->q.sdesc);
                        __skb_queue_purge(&q->sendq);
                        free_txq(adap, &q->q);
                }
        }

        /* clean up control Tx queues */
        for (i = 0; i < ARRAY_SIZE(adap->sge.ctrlq); i++) {
                struct sge_ctrl_txq *cq = &adap->sge.ctrlq[i];

                if (cq->q.desc) {
                        tasklet_kill(&cq->qresume_tsk);
                        t4_ctrl_eq_free(adap, adap->fn, adap->fn, 0,
                                        cq->q.cntxt_id);
                        __skb_queue_purge(&cq->sendq);
                        free_txq(adap, &cq->q);
                }
        }

        if (adap->sge.fw_evtq.desc)
                free_rspq_fl(adap, &adap->sge.fw_evtq, NULL);

        if (adap->sge.intrq.desc)
                free_rspq_fl(adap, &adap->sge.intrq, NULL);

        /* clear the reverse egress queue map */
        memset(adap->sge.egr_map, 0, sizeof(adap->sge.egr_map));
}

void t4_sge_start(struct adapter *adap)
{
        adap->sge.ethtxq_rover = 0;
        mod_timer(&adap->sge.rx_timer, jiffies + RX_QCHECK_PERIOD);
        mod_timer(&adap->sge.tx_timer, jiffies + TX_QCHECK_PERIOD);
}

/**
 *      t4_sge_stop - disable SGE operation
 *      @adap: the adapter
 *
 *      Stop tasklets and timers associated with the DMA engine.  Note that
 *      this is effective only if measures have been taken to disable any HW
 *      events that may restart them.
 */
void t4_sge_stop(struct adapter *adap)
{
        int i;
        struct sge *s = &adap->sge;

        if (in_interrupt())  /* actions below require waiting */
                return;

        if (s->rx_timer.function)
                del_timer_sync(&s->rx_timer);
        if (s->tx_timer.function)
                del_timer_sync(&s->tx_timer);

        for (i = 0; i < ARRAY_SIZE(s->ofldtxq); i++) {
                struct sge_ofld_txq *q = &s->ofldtxq[i];

                if (q->q.desc)
                        tasklet_kill(&q->qresume_tsk);
        }
        for (i = 0; i < ARRAY_SIZE(s->ctrlq); i++) {
                struct sge_ctrl_txq *cq = &s->ctrlq[i];

                if (cq->q.desc)
                        tasklet_kill(&cq->qresume_tsk);
        }
}

/**
 *      t4_sge_init - initialize SGE
 *      @adap: the adapter
 *
 *      Performs SGE initialization needed every time after a chip reset.
 *      We do not initialize any of the queues here, instead the driver
 *      top-level must request them individually.
 */
void t4_sge_init(struct adapter *adap)
{
        unsigned int i, v;
        struct sge *s = &adap->sge;
        unsigned int fl_align_log = ilog2(FL_ALIGN);

        t4_set_reg_field(adap, SGE_CONTROL, PKTSHIFT_MASK |
                         INGPADBOUNDARY_MASK | EGRSTATUSPAGESIZE,
                         INGPADBOUNDARY(fl_align_log - 5) | PKTSHIFT(2) |
                         RXPKTCPLMODE |
                         (STAT_LEN == 128 ? EGRSTATUSPAGESIZE : 0));

        for (i = v = 0; i < 32; i += 4)
                v |= (PAGE_SHIFT - 10) << i;
        t4_write_reg(adap, SGE_HOST_PAGE_SIZE, v);
        t4_write_reg(adap, SGE_FL_BUFFER_SIZE0, PAGE_SIZE);
#if FL_PG_ORDER > 0
        t4_write_reg(adap, SGE_FL_BUFFER_SIZE1, PAGE_SIZE << FL_PG_ORDER);
#endif
        t4_write_reg(adap, SGE_INGRESS_RX_THRESHOLD,
                     THRESHOLD_0(s->counter_val[0]) |
                     THRESHOLD_1(s->counter_val[1]) |
                     THRESHOLD_2(s->counter_val[2]) |
                     THRESHOLD_3(s->counter_val[3]));
        t4_write_reg(adap, SGE_TIMER_VALUE_0_AND_1,
                     TIMERVALUE0(us_to_core_ticks(adap, s->timer_val[0])) |
                     TIMERVALUE1(us_to_core_ticks(adap, s->timer_val[1])));
        t4_write_reg(adap, SGE_TIMER_VALUE_2_AND_3,
                     TIMERVALUE0(us_to_core_ticks(adap, s->timer_val[2])) |
                     TIMERVALUE1(us_to_core_ticks(adap, s->timer_val[3])));
        t4_write_reg(adap, SGE_TIMER_VALUE_4_AND_5,
                     TIMERVALUE0(us_to_core_ticks(adap, s->timer_val[4])) |
                     TIMERVALUE1(us_to_core_ticks(adap, s->timer_val[5])));
        setup_timer(&s->rx_timer, sge_rx_timer_cb, (unsigned long)adap);
        setup_timer(&s->tx_timer, sge_tx_timer_cb, (unsigned long)adap);
        s->starve_thres = core_ticks_per_usec(adap) * 1000000;  /* 1 s */
        s->idma_state[0] = s->idma_state[1] = 0;
        spin_lock_init(&s->intrq_lock);
}