/*
 * Copyright (c) 2006, 2007, 2008, 2009 QLogic Corporation. All rights reserved.
 * Copyright (c) 2005, 2006 PathScale, 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/spinlock.h>

#include "qib.h"
#include "qib_mad.h"

/*
 * Convert the AETH RNR timeout code into the number of microseconds.
 */
const u32 ib_qib_rnr_table[32] = {
        655360, /* 00: 655.36 */
        10,     /* 01:    .01 */
        20,     /* 02     .02 */
        30,     /* 03:    .03 */
        40,     /* 04:    .04 */
        60,     /* 05:    .06 */
        80,     /* 06:    .08 */
        120,    /* 07:    .12 */
        160,    /* 08:    .16 */
        240,    /* 09:    .24 */
        320,    /* 0A:    .32 */
        480,    /* 0B:    .48 */
        640,    /* 0C:    .64 */
        960,    /* 0D:    .96 */
        1280,   /* 0E:   1.28 */
        1920,   /* 0F:   1.92 */
        2560,   /* 10:   2.56 */
        3840,   /* 11:   3.84 */
        5120,   /* 12:   5.12 */
        7680,   /* 13:   7.68 */
        10240,  /* 14:  10.24 */
        15360,  /* 15:  15.36 */
        20480,  /* 16:  20.48 */
        30720,  /* 17:  30.72 */
        40960,  /* 18:  40.96 */
        61440,  /* 19:  61.44 */
        81920,  /* 1A:  81.92 */
        122880, /* 1B: 122.88 */
        163840, /* 1C: 163.84 */
        245760, /* 1D: 245.76 */
        327680, /* 1E: 327.68 */
        491520  /* 1F: 491.52 */
};

/*
 * Validate a RWQE and fill in the SGE state.
 * Return 1 if OK.
 */
static int qib_init_sge(struct qib_qp *qp, struct qib_rwqe *wqe)
{
        int i, j, ret;
        struct ib_wc wc;
        struct qib_lkey_table *rkt;
        struct qib_pd *pd;
        struct qib_sge_state *ss;

        rkt = &to_idev(qp->ibqp.device)->lk_table;
        pd = to_ipd(qp->ibqp.srq ? qp->ibqp.srq->pd : qp->ibqp.pd);
        ss = &qp->r_sge;
        ss->sg_list = qp->r_sg_list;
        qp->r_len = 0;
        for (i = j = 0; i < wqe->num_sge; i++) {
                if (wqe->sg_list[i].length == 0)
                        continue;
                /* Check LKEY */
                if (!qib_lkey_ok(rkt, pd, j ? &ss->sg_list[j - 1] : &ss->sge,
                                 &wqe->sg_list[i], IB_ACCESS_LOCAL_WRITE))
                        goto bad_lkey;
                qp->r_len += wqe->sg_list[i].length;
                j++;
        }
        ss->num_sge = j;
        ss->total_len = qp->r_len;
        ret = 1;
        goto bail;

bad_lkey:
        while (j) {
                struct qib_sge *sge = --j ? &ss->sg_list[j - 1] : &ss->sge;

                qib_put_mr(sge->mr);
        }
        ss->num_sge = 0;
        memset(&wc, 0, sizeof(wc));
        wc.wr_id = wqe->wr_id;
        wc.status = IB_WC_LOC_PROT_ERR;
        wc.opcode = IB_WC_RECV;
        wc.qp = &qp->ibqp;
        /* Signal solicited completion event. */
        qib_cq_enter(to_icq(qp->ibqp.recv_cq), &wc, 1);
        ret = 0;
bail:
        return ret;
}

/**
 * qib_get_rwqe - copy the next RWQE into the QP's RWQE
 * @qp: the QP
 * @wr_id_only: update qp->r_wr_id only, not qp->r_sge
 *
 * Return -1 if there is a local error, 0 if no RWQE is available,
 * otherwise return 1.
 *
 * Can be called from interrupt level.
 */
int qib_get_rwqe(struct qib_qp *qp, int wr_id_only)
{
        unsigned long flags;
        struct qib_rq *rq;
        struct qib_rwq *wq;
        struct qib_srq *srq;
        struct qib_rwqe *wqe;
        void (*handler)(struct ib_event *, void *);
        u32 tail;
        int ret;

        if (qp->ibqp.srq) {
                srq = to_isrq(qp->ibqp.srq);
                handler = srq->ibsrq.event_handler;
                rq = &srq->rq;
        } else {
                srq = NULL;
                handler = NULL;
                rq = &qp->r_rq;
        }

        spin_lock_irqsave(&rq->lock, flags);
        if (!(ib_qib_state_ops[qp->state] & QIB_PROCESS_RECV_OK)) {
                ret = 0;
                goto unlock;
        }

        wq = rq->wq;
        tail = wq->tail;
        /* Validate tail before using it since it is user writable. */
        if (tail >= rq->size)
                tail = 0;
        if (unlikely(tail == wq->head)) {
                ret = 0;
                goto unlock;
        }
        /* Make sure entry is read after head index is read. */
        smp_rmb();
        wqe = get_rwqe_ptr(rq, tail);
        /*
         * Even though we update the tail index in memory, the verbs
         * consumer is not supposed to post more entries until a
         * completion is generated.
         */
        if (++tail >= rq->size)
                tail = 0;
        wq->tail = tail;
        if (!wr_id_only && !qib_init_sge(qp, wqe)) {
                ret = -1;
                goto unlock;
        }
        qp->r_wr_id = wqe->wr_id;

        ret = 1;
        set_bit(QIB_R_WRID_VALID, &qp->r_aflags);
        if (handler) {
                u32 n;

                /*
                 * Validate head pointer value and compute
                 * the number of remaining WQEs.
                 */
                n = wq->head;
                if (n >= rq->size)
                        n = 0;
                if (n < tail)
                        n += rq->size - tail;
                else
                        n -= tail;
                if (n < srq->limit) {
                        struct ib_event ev;

                        srq->limit = 0;
                        spin_unlock_irqrestore(&rq->lock, flags);
                        ev.device = qp->ibqp.device;
                        ev.element.srq = qp->ibqp.srq;
                        ev.event = IB_EVENT_SRQ_LIMIT_REACHED;
                        handler(&ev, srq->ibsrq.srq_context);
                        goto bail;
                }
        }
unlock:
        spin_unlock_irqrestore(&rq->lock, flags);
bail:
        return ret;
}

/*
 * Switch to alternate path.
 * The QP s_lock should be held and interrupts disabled.
 */
void qib_migrate_qp(struct qib_qp *qp)
{
        struct ib_event ev;

        qp->s_mig_state = IB_MIG_MIGRATED;
        qp->remote_ah_attr = qp->alt_ah_attr;
        qp->port_num = qp->alt_ah_attr.port_num;
        qp->s_pkey_index = qp->s_alt_pkey_index;

        ev.device = qp->ibqp.device;
        ev.element.qp = &qp->ibqp;
        ev.event = IB_EVENT_PATH_MIG;
        qp->ibqp.event_handler(&ev, qp->ibqp.qp_context);
}

static __be64 get_sguid(struct qib_ibport *ibp, unsigned index)
{
        if (!index) {
                struct qib_pportdata *ppd = ppd_from_ibp(ibp);

                return ppd->guid;
        } else
                return ibp->guids[index - 1];
}

static int gid_ok(union ib_gid *gid, __be64 gid_prefix, __be64 id)
{
        return (gid->global.interface_id == id &&
                (gid->global.subnet_prefix == gid_prefix ||
                 gid->global.subnet_prefix == IB_DEFAULT_GID_PREFIX));
}

/*
 *
 * This should be called with the QP r_lock held.
 *
 * The s_lock will be acquired around the qib_migrate_qp() call.
 */
int qib_ruc_check_hdr(struct qib_ibport *ibp, struct qib_ib_header *hdr,
                      int has_grh, struct qib_qp *qp, u32 bth0)
{
        __be64 guid;
        unsigned long flags;

        if (qp->s_mig_state == IB_MIG_ARMED && (bth0 & IB_BTH_MIG_REQ)) {
                if (!has_grh) {
                        if (qp->alt_ah_attr.ah_flags & IB_AH_GRH)
                                goto err;
                } else {
                        if (!(qp->alt_ah_attr.ah_flags & IB_AH_GRH))
                                goto err;
                        guid = get_sguid(ibp, qp->alt_ah_attr.grh.sgid_index);
                        if (!gid_ok(&hdr->u.l.grh.dgid, ibp->gid_prefix, guid))
                                goto err;
                        if (!gid_ok(&hdr->u.l.grh.sgid,
                            qp->alt_ah_attr.grh.dgid.global.subnet_prefix,
                            qp->alt_ah_attr.grh.dgid.global.interface_id))
                                goto err;
                }
                if (!qib_pkey_ok((u16)bth0,
                                 qib_get_pkey(ibp, qp->s_alt_pkey_index))) {
                        qib_bad_pqkey(ibp, IB_NOTICE_TRAP_BAD_PKEY,
                                      (u16)bth0,
                                      (be16_to_cpu(hdr->lrh[0]) >> 4) & 0xF,
                                      0, qp->ibqp.qp_num,
                                      hdr->lrh[3], hdr->lrh[1]);
                        goto err;
                }
                /* Validate the SLID. See Ch. 9.6.1.5 and 17.2.8 */
                if (be16_to_cpu(hdr->lrh[3]) != qp->alt_ah_attr.dlid ||
                    ppd_from_ibp(ibp)->port != qp->alt_ah_attr.port_num)
                        goto err;
                spin_lock_irqsave(&qp->s_lock, flags);
                qib_migrate_qp(qp);
                spin_unlock_irqrestore(&qp->s_lock, flags);
        } else {
                if (!has_grh) {
                        if (qp->remote_ah_attr.ah_flags & IB_AH_GRH)
                                goto err;
                } else {
                        if (!(qp->remote_ah_attr.ah_flags & IB_AH_GRH))
                                goto err;
                        guid = get_sguid(ibp,
                                         qp->remote_ah_attr.grh.sgid_index);
                        if (!gid_ok(&hdr->u.l.grh.dgid, ibp->gid_prefix, guid))
                                goto err;
                        if (!gid_ok(&hdr->u.l.grh.sgid,
                            qp->remote_ah_attr.grh.dgid.global.subnet_prefix,
                            qp->remote_ah_attr.grh.dgid.global.interface_id))
                                goto err;
                }
                if (!qib_pkey_ok((u16)bth0,
                                 qib_get_pkey(ibp, qp->s_pkey_index))) {
                        qib_bad_pqkey(ibp, IB_NOTICE_TRAP_BAD_PKEY,
                                      (u16)bth0,
                                      (be16_to_cpu(hdr->lrh[0]) >> 4) & 0xF,
                                      0, qp->ibqp.qp_num,
                                      hdr->lrh[3], hdr->lrh[1]);
                        goto err;
                }
                /* Validate the SLID. See Ch. 9.6.1.5 */
                if (be16_to_cpu(hdr->lrh[3]) != qp->remote_ah_attr.dlid ||
                    ppd_from_ibp(ibp)->port != qp->port_num)
                        goto err;
                if (qp->s_mig_state == IB_MIG_REARM &&
                    !(bth0 & IB_BTH_MIG_REQ))
                        qp->s_mig_state = IB_MIG_ARMED;
        }

        return 0;

err:
        return 1;
}

/**
 * qib_ruc_loopback - handle UC and RC lookback requests
 * @sqp: the sending QP
 *
 * This is called from qib_do_send() to
 * forward a WQE addressed to the same HCA.
 * Note that although we are single threaded due to the tasklet, we still
 * have to protect against post_send().  We don't have to worry about
 * receive interrupts since this is a connected protocol and all packets
 * will pass through here.
 */
static void qib_ruc_loopback(struct qib_qp *sqp)
{
        struct qib_ibport *ibp = to_iport(sqp->ibqp.device, sqp->port_num);
        struct qib_qp *qp;
        struct qib_swqe *wqe;
        struct qib_sge *sge;
        unsigned long flags;
        struct ib_wc wc;
        u64 sdata;
        atomic64_t *maddr;
        enum ib_wc_status send_status;
        int release;
        int ret;

        /*
         * Note that we check the responder QP state after
         * checking the requester's state.
         */
        qp = qib_lookup_qpn(ibp, sqp->remote_qpn);

        spin_lock_irqsave(&sqp->s_lock, flags);

        /* Return if we are already busy processing a work request. */
        if ((sqp->s_flags & (QIB_S_BUSY | QIB_S_ANY_WAIT)) ||
            !(ib_qib_state_ops[sqp->state] & QIB_PROCESS_OR_FLUSH_SEND))
                goto unlock;

        sqp->s_flags |= QIB_S_BUSY;

again:
        if (sqp->s_last == sqp->s_head)
                goto clr_busy;
        wqe = get_swqe_ptr(sqp, sqp->s_last);

        /* Return if it is not OK to start a new work reqeust. */
        if (!(ib_qib_state_ops[sqp->state] & QIB_PROCESS_NEXT_SEND_OK)) {
                if (!(ib_qib_state_ops[sqp->state] & QIB_FLUSH_SEND))
                        goto clr_busy;
                /* We are in the error state, flush the work request. */
                send_status = IB_WC_WR_FLUSH_ERR;
                goto flush_send;
        }

        /*
         * We can rely on the entry not changing without the s_lock
         * being held until we update s_last.
         * We increment s_cur to indicate s_last is in progress.
         */
        if (sqp->s_last == sqp->s_cur) {
                if (++sqp->s_cur >= sqp->s_size)
                        sqp->s_cur = 0;
        }
        spin_unlock_irqrestore(&sqp->s_lock, flags);

        if (!qp || !(ib_qib_state_ops[qp->state] & QIB_PROCESS_RECV_OK) ||
            qp->ibqp.qp_type != sqp->ibqp.qp_type) {
                ibp->n_pkt_drops++;
                /*
                 * For RC, the requester would timeout and retry so
                 * shortcut the timeouts and just signal too many retries.
                 */
                if (sqp->ibqp.qp_type == IB_QPT_RC)
                        send_status = IB_WC_RETRY_EXC_ERR;
                else
                        send_status = IB_WC_SUCCESS;
                goto serr;
        }

        memset(&wc, 0, sizeof wc);
        send_status = IB_WC_SUCCESS;

        release = 1;
        sqp->s_sge.sge = wqe->sg_list[0];
        sqp->s_sge.sg_list = wqe->sg_list + 1;
        sqp->s_sge.num_sge = wqe->wr.num_sge;
        sqp->s_len = wqe->length;
        switch (wqe->wr.opcode) {
        case IB_WR_SEND_WITH_IMM:
                wc.wc_flags = IB_WC_WITH_IMM;
                wc.ex.imm_data = wqe->wr.ex.imm_data;
                /* FALLTHROUGH */
        case IB_WR_SEND:
                ret = qib_get_rwqe(qp, 0);
                if (ret < 0)
                        goto op_err;
                if (!ret)
                        goto rnr_nak;
                break;

        case IB_WR_RDMA_WRITE_WITH_IMM:
                if (unlikely(!(qp->qp_access_flags & IB_ACCESS_REMOTE_WRITE)))
                        goto inv_err;
                wc.wc_flags = IB_WC_WITH_IMM;
                wc.ex.imm_data = wqe->wr.ex.imm_data;
                ret = qib_get_rwqe(qp, 1);
                if (ret < 0)
                        goto op_err;
                if (!ret)
                        goto rnr_nak;
                /* FALLTHROUGH */
        case IB_WR_RDMA_WRITE:
                if (unlikely(!(qp->qp_access_flags & IB_ACCESS_REMOTE_WRITE)))
                        goto inv_err;
                if (wqe->length == 0)
                        break;
                if (unlikely(!qib_rkey_ok(qp, &qp->r_sge.sge, wqe->length,
                                          wqe->wr.wr.rdma.remote_addr,
                                          wqe->wr.wr.rdma.rkey,
                                          IB_ACCESS_REMOTE_WRITE)))
                        goto acc_err;
                qp->r_sge.sg_list = NULL;
                qp->r_sge.num_sge = 1;
                qp->r_sge.total_len = wqe->length;
                break;

        case IB_WR_RDMA_READ:
                if (unlikely(!(qp->qp_access_flags & IB_ACCESS_REMOTE_READ)))
                        goto inv_err;
                if (unlikely(!qib_rkey_ok(qp, &sqp->s_sge.sge, wqe->length,
                                          wqe->wr.wr.rdma.remote_addr,
                                          wqe->wr.wr.rdma.rkey,
                                          IB_ACCESS_REMOTE_READ)))
                        goto acc_err;
                release = 0;
                sqp->s_sge.sg_list = NULL;
                sqp->s_sge.num_sge = 1;
                qp->r_sge.sge = wqe->sg_list[0];
                qp->r_sge.sg_list = wqe->sg_list + 1;
                qp->r_sge.num_sge = wqe->wr.num_sge;
                qp->r_sge.total_len = wqe->length;
                break;

        case IB_WR_ATOMIC_CMP_AND_SWP:
        case IB_WR_ATOMIC_FETCH_AND_ADD:
                if (unlikely(!(qp->qp_access_flags & IB_ACCESS_REMOTE_ATOMIC)))
                        goto inv_err;
                if (unlikely(!qib_rkey_ok(qp, &qp->r_sge.sge, sizeof(u64),
                                          wqe->wr.wr.atomic.remote_addr,
                                          wqe->wr.wr.atomic.rkey,
                                          IB_ACCESS_REMOTE_ATOMIC)))
                        goto acc_err;
                /* Perform atomic OP and save result. */
                maddr = (atomic64_t *) qp->r_sge.sge.vaddr;
                sdata = wqe->wr.wr.atomic.compare_add;
                *(u64 *) sqp->s_sge.sge.vaddr =
                        (wqe->wr.opcode == IB_WR_ATOMIC_FETCH_AND_ADD) ?
                        (u64) atomic64_add_return(sdata, maddr) - sdata :
                        (u64) cmpxchg((u64 *) qp->r_sge.sge.vaddr,
                                      sdata, wqe->wr.wr.atomic.swap);
                qib_put_mr(qp->r_sge.sge.mr);
                qp->r_sge.num_sge = 0;
                goto send_comp;

        default:
                send_status = IB_WC_LOC_QP_OP_ERR;
                goto serr;
        }

        sge = &sqp->s_sge.sge;
        while (sqp->s_len) {
                u32 len = sqp->s_len;

                if (len > sge->length)
                        len = sge->length;
                if (len > sge->sge_length)
                        len = sge->sge_length;
                BUG_ON(len == 0);
                qib_copy_sge(&qp->r_sge, sge->vaddr, len, release);
                sge->vaddr += len;
                sge->length -= len;
                sge->sge_length -= len;
                if (sge->sge_length == 0) {
                        if (!release)
                                qib_put_mr(sge->mr);
                        if (--sqp->s_sge.num_sge)
                                *sge = *sqp->s_sge.sg_list++;
                } else if (sge->length == 0 && sge->mr->lkey) {
                        if (++sge->n >= QIB_SEGSZ) {
                                if (++sge->m >= sge->mr->mapsz)
                                        break;
                                sge->n = 0;
                        }
                        sge->vaddr =
                                sge->mr->map[sge->m]->segs[sge->n].vaddr;
                        sge->length =
                                sge->mr->map[sge->m]->segs[sge->n].length;
                }
                sqp->s_len -= len;
        }
        if (release)
                qib_put_ss(&qp->r_sge);

        if (!test_and_clear_bit(QIB_R_WRID_VALID, &qp->r_aflags))
                goto send_comp;

        if (wqe->wr.opcode == IB_WR_RDMA_WRITE_WITH_IMM)
                wc.opcode = IB_WC_RECV_RDMA_WITH_IMM;
        else
                wc.opcode = IB_WC_RECV;
        wc.wr_id = qp->r_wr_id;
        wc.status = IB_WC_SUCCESS;
        wc.byte_len = wqe->length;
        wc.qp = &qp->ibqp;
        wc.src_qp = qp->remote_qpn;
        wc.slid = qp->remote_ah_attr.dlid;
        wc.sl = qp->remote_ah_attr.sl;
        wc.port_num = 1;
        /* Signal completion event if the solicited bit is set. */
        qib_cq_enter(to_icq(qp->ibqp.recv_cq), &wc,
                       wqe->wr.send_flags & IB_SEND_SOLICITED);

send_comp:
        spin_lock_irqsave(&sqp->s_lock, flags);
        ibp->n_loop_pkts++;
flush_send:
        sqp->s_rnr_retry = sqp->s_rnr_retry_cnt;
        qib_send_complete(sqp, wqe, send_status);
        goto again;

rnr_nak:
        /* Handle RNR NAK */
        if (qp->ibqp.qp_type == IB_QPT_UC)
                goto send_comp;
        ibp->n_rnr_naks++;
        /*
         * Note: we don't need the s_lock held since the BUSY flag
         * makes this single threaded.
         */
        if (sqp->s_rnr_retry == 0) {
                send_status = IB_WC_RNR_RETRY_EXC_ERR;
                goto serr;
        }
        if (sqp->s_rnr_retry_cnt < 7)
                sqp->s_rnr_retry--;
        spin_lock_irqsave(&sqp->s_lock, flags);
        if (!(ib_qib_state_ops[sqp->state] & QIB_PROCESS_RECV_OK))
                goto clr_busy;
        sqp->s_flags |= QIB_S_WAIT_RNR;
        sqp->s_timer.function = qib_rc_rnr_retry;
        sqp->s_timer.expires = jiffies +
                usecs_to_jiffies(ib_qib_rnr_table[qp->r_min_rnr_timer]);
        add_timer(&sqp->s_timer);
        goto clr_busy;

op_err:
        send_status = IB_WC_REM_OP_ERR;
        wc.status = IB_WC_LOC_QP_OP_ERR;
        goto err;

inv_err:
        send_status = IB_WC_REM_INV_REQ_ERR;
        wc.status = IB_WC_LOC_QP_OP_ERR;
        goto err;

acc_err:
        send_status = IB_WC_REM_ACCESS_ERR;
        wc.status = IB_WC_LOC_PROT_ERR;
err:
        /* responder goes to error state */
        qib_rc_error(qp, wc.status);

serr:
        spin_lock_irqsave(&sqp->s_lock, flags);
        qib_send_complete(sqp, wqe, send_status);
        if (sqp->ibqp.qp_type == IB_QPT_RC) {
                int lastwqe = qib_error_qp(sqp, IB_WC_WR_FLUSH_ERR);

                sqp->s_flags &= ~QIB_S_BUSY;
                spin_unlock_irqrestore(&sqp->s_lock, flags);
                if (lastwqe) {
                        struct ib_event ev;

                        ev.device = sqp->ibqp.device;
                        ev.element.qp = &sqp->ibqp;
                        ev.event = IB_EVENT_QP_LAST_WQE_REACHED;
                        sqp->ibqp.event_handler(&ev, sqp->ibqp.qp_context);
                }
                goto done;
        }
clr_busy:
        sqp->s_flags &= ~QIB_S_BUSY;
unlock:
        spin_unlock_irqrestore(&sqp->s_lock, flags);
done:
        if (qp && atomic_dec_and_test(&qp->refcount))
                wake_up(&qp->wait);
}

/**
 * qib_make_grh - construct a GRH header
 * @ibp: a pointer to the IB port
 * @hdr: a pointer to the GRH header being constructed
 * @grh: the global route address to send to
 * @hwords: the number of 32 bit words of header being sent
 * @nwords: the number of 32 bit words of data being sent
 *
 * Return the size of the header in 32 bit words.
 */
u32 qib_make_grh(struct qib_ibport *ibp, struct ib_grh *hdr,
                 struct ib_global_route *grh, u32 hwords, u32 nwords)
{
        hdr->version_tclass_flow =
                cpu_to_be32((IB_GRH_VERSION << IB_GRH_VERSION_SHIFT) |
                            (grh->traffic_class << IB_GRH_TCLASS_SHIFT) |
                            (grh->flow_label << IB_GRH_FLOW_SHIFT));
        hdr->paylen = cpu_to_be16((hwords - 2 + nwords + SIZE_OF_CRC) << 2);
        /* next_hdr is defined by C8-7 in ch. 8.4.1 */
        hdr->next_hdr = IB_GRH_NEXT_HDR;
        hdr->hop_limit = grh->hop_limit;
        /* The SGID is 32-bit aligned. */
        hdr->sgid.global.subnet_prefix = ibp->gid_prefix;
        hdr->sgid.global.interface_id = grh->sgid_index ?
                ibp->guids[grh->sgid_index - 1] : ppd_from_ibp(ibp)->guid;
        hdr->dgid = grh->dgid;

        /* GRH header size in 32-bit words. */
        return sizeof(struct ib_grh) / sizeof(u32);
}

void qib_make_ruc_header(struct qib_qp *qp, struct qib_other_headers *ohdr,
                         u32 bth0, u32 bth2)
{
        struct qib_ibport *ibp = to_iport(qp->ibqp.device, qp->port_num);
        u16 lrh0;
        u32 nwords;
        u32 extra_bytes;

        /* Construct the header. */
        extra_bytes = -qp->s_cur_size & 3;
        nwords = (qp->s_cur_size + extra_bytes) >> 2;
        lrh0 = QIB_LRH_BTH;
        if (unlikely(qp->remote_ah_attr.ah_flags & IB_AH_GRH)) {
                qp->s_hdrwords += qib_make_grh(ibp, &qp->s_hdr->u.l.grh,
                                               &qp->remote_ah_attr.grh,
                                               qp->s_hdrwords, nwords);
                lrh0 = QIB_LRH_GRH;
        }
        lrh0 |= ibp->sl_to_vl[qp->remote_ah_attr.sl] << 12 |
                qp->remote_ah_attr.sl << 4;
        qp->s_hdr->lrh[0] = cpu_to_be16(lrh0);
        qp->s_hdr->lrh[1] = cpu_to_be16(qp->remote_ah_attr.dlid);
        qp->s_hdr->lrh[2] = cpu_to_be16(qp->s_hdrwords + nwords + SIZE_OF_CRC);
        qp->s_hdr->lrh[3] = cpu_to_be16(ppd_from_ibp(ibp)->lid |
                                       qp->remote_ah_attr.src_path_bits);
        bth0 |= qib_get_pkey(ibp, qp->s_pkey_index);
        bth0 |= extra_bytes << 20;
        if (qp->s_mig_state == IB_MIG_MIGRATED)
                bth0 |= IB_BTH_MIG_REQ;
        ohdr->bth[0] = cpu_to_be32(bth0);
        ohdr->bth[1] = cpu_to_be32(qp->remote_qpn);
        ohdr->bth[2] = cpu_to_be32(bth2);
}

/**
 * qib_do_send - perform a send on a QP
 * @work: contains a pointer to the QP
 *
 * Process entries in the send work queue until credit or queue is
 * exhausted.  Only allow one CPU to send a packet per QP (tasklet).
 * Otherwise, two threads could send packets out of order.
 */
void qib_do_send(struct work_struct *work)
{
        struct qib_qp *qp = container_of(work, struct qib_qp, s_work);
        struct qib_ibport *ibp = to_iport(qp->ibqp.device, qp->port_num);
        struct qib_pportdata *ppd = ppd_from_ibp(ibp);
        int (*make_req)(struct qib_qp *qp);
        unsigned long flags;

        if ((qp->ibqp.qp_type == IB_QPT_RC ||
             qp->ibqp.qp_type == IB_QPT_UC) &&
            (qp->remote_ah_attr.dlid & ~((1 << ppd->lmc) - 1)) == ppd->lid) {
                qib_ruc_loopback(qp);
                return;
        }

        if (qp->ibqp.qp_type == IB_QPT_RC)
                make_req = qib_make_rc_req;
        else if (qp->ibqp.qp_type == IB_QPT_UC)
                make_req = qib_make_uc_req;
        else
                make_req = qib_make_ud_req;

        spin_lock_irqsave(&qp->s_lock, flags);

        /* Return if we are already busy processing a work request. */
        if (!qib_send_ok(qp)) {
                spin_unlock_irqrestore(&qp->s_lock, flags);
                return;
        }

        qp->s_flags |= QIB_S_BUSY;

        spin_unlock_irqrestore(&qp->s_lock, flags);

        do {
                /* Check for a constructed packet to be sent. */
                if (qp->s_hdrwords != 0) {
                        /*
                         * If the packet cannot be sent now, return and
                         * the send tasklet will be woken up later.
                         */
                        if (qib_verbs_send(qp, qp->s_hdr, qp->s_hdrwords,
                                           qp->s_cur_sge, qp->s_cur_size))
                                break;
                        /* Record that s_hdr is empty. */
                        qp->s_hdrwords = 0;
                }
        } while (make_req(qp));
}

/*
 * This should be called with s_lock held.
 */
void qib_send_complete(struct qib_qp *qp, struct qib_swqe *wqe,
                       enum ib_wc_status status)
{
        u32 old_last, last;
        unsigned i;

        if (!(ib_qib_state_ops[qp->state] & QIB_PROCESS_OR_FLUSH_SEND))
                return;

        for (i = 0; i < wqe->wr.num_sge; i++) {
                struct qib_sge *sge = &wqe->sg_list[i];

                qib_put_mr(sge->mr);
        }
        if (qp->ibqp.qp_type == IB_QPT_UD ||
            qp->ibqp.qp_type == IB_QPT_SMI ||
            qp->ibqp.qp_type == IB_QPT_GSI)
                atomic_dec(&to_iah(wqe->wr.wr.ud.ah)->refcount);

        /* See ch. 11.2.4.1 and 10.7.3.1 */
        if (!(qp->s_flags & QIB_S_SIGNAL_REQ_WR) ||
            (wqe->wr.send_flags & IB_SEND_SIGNALED) ||
            status != IB_WC_SUCCESS) {
                struct ib_wc wc;

                memset(&wc, 0, sizeof wc);
                wc.wr_id = wqe->wr.wr_id;
                wc.status = status;
                wc.opcode = ib_qib_wc_opcode[wqe->wr.opcode];
                wc.qp = &qp->ibqp;
                if (status == IB_WC_SUCCESS)
                        wc.byte_len = wqe->length;
                qib_cq_enter(to_icq(qp->ibqp.send_cq), &wc,
                             status != IB_WC_SUCCESS);
        }

        last = qp->s_last;
        old_last = last;
        if (++last >= qp->s_size)
                last = 0;
        qp->s_last = last;
        if (qp->s_acked == old_last)
                qp->s_acked = last;
        if (qp->s_cur == old_last)
                qp->s_cur = last;
        if (qp->s_tail == old_last)
                qp->s_tail = last;
        if (qp->state == IB_QPS_SQD && last == qp->s_cur)
                qp->s_draining = 0;
}