Merge tag 'for_linus' of git://git.kernel.org/pub/scm/linux/kernel/git/mst/vhost

[cris-mirror.git] / drivers / infiniband / hw / qib / qib_sdma.c

/*
 * Copyright (c) 2012 Intel Corporation. All rights reserved.
 * Copyright (c) 2007 - 2012 QLogic Corporation. 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 <linux/netdevice.h>
#include <linux/moduleparam.h>

#include "qib.h"
#include "qib_common.h"

/* default pio off, sdma on */
static ushort sdma_descq_cnt = 256;
module_param_named(sdma_descq_cnt, sdma_descq_cnt, ushort, S_IRUGO);
MODULE_PARM_DESC(sdma_descq_cnt, "Number of SDMA descq entries");

/*
 * Bits defined in the send DMA descriptor.
 */
#define SDMA_DESC_LAST          (1ULL << 11)
#define SDMA_DESC_FIRST         (1ULL << 12)
#define SDMA_DESC_DMA_HEAD      (1ULL << 13)
#define SDMA_DESC_USE_LARGE_BUF (1ULL << 14)
#define SDMA_DESC_INTR          (1ULL << 15)
#define SDMA_DESC_COUNT_LSB     16
#define SDMA_DESC_GEN_LSB       30

char *qib_sdma_state_names[] = {
        [qib_sdma_state_s00_hw_down]          = "s00_HwDown",
        [qib_sdma_state_s10_hw_start_up_wait] = "s10_HwStartUpWait",
        [qib_sdma_state_s20_idle]             = "s20_Idle",
        [qib_sdma_state_s30_sw_clean_up_wait] = "s30_SwCleanUpWait",
        [qib_sdma_state_s40_hw_clean_up_wait] = "s40_HwCleanUpWait",
        [qib_sdma_state_s50_hw_halt_wait]     = "s50_HwHaltWait",
        [qib_sdma_state_s99_running]          = "s99_Running",
};

char *qib_sdma_event_names[] = {
        [qib_sdma_event_e00_go_hw_down]   = "e00_GoHwDown",
        [qib_sdma_event_e10_go_hw_start]  = "e10_GoHwStart",
        [qib_sdma_event_e20_hw_started]   = "e20_HwStarted",
        [qib_sdma_event_e30_go_running]   = "e30_GoRunning",
        [qib_sdma_event_e40_sw_cleaned]   = "e40_SwCleaned",
        [qib_sdma_event_e50_hw_cleaned]   = "e50_HwCleaned",
        [qib_sdma_event_e60_hw_halted]    = "e60_HwHalted",
        [qib_sdma_event_e70_go_idle]      = "e70_GoIdle",
        [qib_sdma_event_e7220_err_halted] = "e7220_ErrHalted",
        [qib_sdma_event_e7322_err_halted] = "e7322_ErrHalted",
        [qib_sdma_event_e90_timer_tick]   = "e90_TimerTick",
};

/* declare all statics here rather than keep sorting */
static int alloc_sdma(struct qib_pportdata *);
static void sdma_complete(struct kref *);
static void sdma_finalput(struct qib_sdma_state *);
static void sdma_get(struct qib_sdma_state *);
static void sdma_put(struct qib_sdma_state *);
static void sdma_set_state(struct qib_pportdata *, enum qib_sdma_states);
static void sdma_start_sw_clean_up(struct qib_pportdata *);
static void sdma_sw_clean_up_task(unsigned long);
static void unmap_desc(struct qib_pportdata *, unsigned);

static void sdma_get(struct qib_sdma_state *ss)
{
        kref_get(&ss->kref);
}

static void sdma_complete(struct kref *kref)
{
        struct qib_sdma_state *ss =
                container_of(kref, struct qib_sdma_state, kref);

        complete(&ss->comp);
}

static void sdma_put(struct qib_sdma_state *ss)
{
        kref_put(&ss->kref, sdma_complete);
}

static void sdma_finalput(struct qib_sdma_state *ss)
{
        sdma_put(ss);
        wait_for_completion(&ss->comp);
}

/*
 * Complete all the sdma requests on the active list, in the correct
 * order, and with appropriate processing.   Called when cleaning up
 * after sdma shutdown, and when new sdma requests are submitted for
 * a link that is down.   This matches what is done for requests
 * that complete normally, it's just the full list.
 *
 * Must be called with sdma_lock held
 */
static void clear_sdma_activelist(struct qib_pportdata *ppd)
{
        struct qib_sdma_txreq *txp, *txp_next;

        list_for_each_entry_safe(txp, txp_next, &ppd->sdma_activelist, list) {
                list_del_init(&txp->list);
                if (txp->flags & QIB_SDMA_TXREQ_F_FREEDESC) {
                        unsigned idx;

                        idx = txp->start_idx;
                        while (idx != txp->next_descq_idx) {
                                unmap_desc(ppd, idx);
                                if (++idx == ppd->sdma_descq_cnt)
                                        idx = 0;
                        }
                }
                if (txp->callback)
                        (*txp->callback)(txp, QIB_SDMA_TXREQ_S_ABORTED);
        }
}

static void sdma_sw_clean_up_task(unsigned long opaque)
{
        struct qib_pportdata *ppd = (struct qib_pportdata *) opaque;
        unsigned long flags;

        spin_lock_irqsave(&ppd->sdma_lock, flags);

        /*
         * At this point, the following should always be true:
         * - We are halted, so no more descriptors are getting retired.
         * - We are not running, so no one is submitting new work.
         * - Only we can send the e40_sw_cleaned, so we can't start
         *   running again until we say so.  So, the active list and
         *   descq are ours to play with.
         */

        /* Process all retired requests. */
        qib_sdma_make_progress(ppd);

        clear_sdma_activelist(ppd);

        /*
         * Resync count of added and removed.  It is VERY important that
         * sdma_descq_removed NEVER decrement - user_sdma depends on it.
         */
        ppd->sdma_descq_removed = ppd->sdma_descq_added;

        /*
         * Reset our notion of head and tail.
         * Note that the HW registers will be reset when switching states
         * due to calling __qib_sdma_process_event() below.
         */
        ppd->sdma_descq_tail = 0;
        ppd->sdma_descq_head = 0;
        ppd->sdma_head_dma[0] = 0;
        ppd->sdma_generation = 0;

        __qib_sdma_process_event(ppd, qib_sdma_event_e40_sw_cleaned);

        spin_unlock_irqrestore(&ppd->sdma_lock, flags);
}

/*
 * This is called when changing to state qib_sdma_state_s10_hw_start_up_wait
 * as a result of send buffer errors or send DMA descriptor errors.
 * We want to disarm the buffers in these cases.
 */
static void sdma_hw_start_up(struct qib_pportdata *ppd)
{
        struct qib_sdma_state *ss = &ppd->sdma_state;
        unsigned bufno;

        for (bufno = ss->first_sendbuf; bufno < ss->last_sendbuf; ++bufno)
                ppd->dd->f_sendctrl(ppd, QIB_SENDCTRL_DISARM_BUF(bufno));

        ppd->dd->f_sdma_hw_start_up(ppd);
}

static void sdma_sw_tear_down(struct qib_pportdata *ppd)
{
        struct qib_sdma_state *ss = &ppd->sdma_state;

        /* Releasing this reference means the state machine has stopped. */
        sdma_put(ss);
}

static void sdma_start_sw_clean_up(struct qib_pportdata *ppd)
{
        tasklet_hi_schedule(&ppd->sdma_sw_clean_up_task);
}

static void sdma_set_state(struct qib_pportdata *ppd,
        enum qib_sdma_states next_state)
{
        struct qib_sdma_state *ss = &ppd->sdma_state;
        struct sdma_set_state_action *action = ss->set_state_action;
        unsigned op = 0;

        /* debugging bookkeeping */
        ss->previous_state = ss->current_state;
        ss->previous_op = ss->current_op;

        ss->current_state = next_state;

        if (action[next_state].op_enable)
                op |= QIB_SDMA_SENDCTRL_OP_ENABLE;

        if (action[next_state].op_intenable)
                op |= QIB_SDMA_SENDCTRL_OP_INTENABLE;

        if (action[next_state].op_halt)
                op |= QIB_SDMA_SENDCTRL_OP_HALT;

        if (action[next_state].op_drain)
                op |= QIB_SDMA_SENDCTRL_OP_DRAIN;

        if (action[next_state].go_s99_running_tofalse)
                ss->go_s99_running = 0;

        if (action[next_state].go_s99_running_totrue)
                ss->go_s99_running = 1;

        ss->current_op = op;

        ppd->dd->f_sdma_sendctrl(ppd, ss->current_op);
}

static void unmap_desc(struct qib_pportdata *ppd, unsigned head)
{
        __le64 *descqp = &ppd->sdma_descq[head].qw[0];
        u64 desc[2];
        dma_addr_t addr;
        size_t len;

        desc[0] = le64_to_cpu(descqp[0]);
        desc[1] = le64_to_cpu(descqp[1]);

        addr = (desc[1] << 32) | (desc[0] >> 32);
        len = (desc[0] >> 14) & (0x7ffULL << 2);
        dma_unmap_single(&ppd->dd->pcidev->dev, addr, len, DMA_TO_DEVICE);
}

static int alloc_sdma(struct qib_pportdata *ppd)
{
        ppd->sdma_descq_cnt = sdma_descq_cnt;
        if (!ppd->sdma_descq_cnt)
                ppd->sdma_descq_cnt = 256;

        /* Allocate memory for SendDMA descriptor FIFO */
        ppd->sdma_descq = dma_alloc_coherent(&ppd->dd->pcidev->dev,
                ppd->sdma_descq_cnt * sizeof(u64[2]), &ppd->sdma_descq_phys,
                GFP_KERNEL);

        if (!ppd->sdma_descq) {
                qib_dev_err(ppd->dd,
                        "failed to allocate SendDMA descriptor FIFO memory\n");
                goto bail;
        }

        /* Allocate memory for DMA of head register to memory */
        ppd->sdma_head_dma = dma_alloc_coherent(&ppd->dd->pcidev->dev,
                PAGE_SIZE, &ppd->sdma_head_phys, GFP_KERNEL);
        if (!ppd->sdma_head_dma) {
                qib_dev_err(ppd->dd,
                        "failed to allocate SendDMA head memory\n");
                goto cleanup_descq;
        }
        ppd->sdma_head_dma[0] = 0;
        return 0;

cleanup_descq:
        dma_free_coherent(&ppd->dd->pcidev->dev,
                ppd->sdma_descq_cnt * sizeof(u64[2]), (void *)ppd->sdma_descq,
                ppd->sdma_descq_phys);
        ppd->sdma_descq = NULL;
        ppd->sdma_descq_phys = 0;
bail:
        ppd->sdma_descq_cnt = 0;
        return -ENOMEM;
}

static void free_sdma(struct qib_pportdata *ppd)
{
        struct qib_devdata *dd = ppd->dd;

        if (ppd->sdma_head_dma) {
                dma_free_coherent(&dd->pcidev->dev, PAGE_SIZE,
                                  (void *)ppd->sdma_head_dma,
                                  ppd->sdma_head_phys);
                ppd->sdma_head_dma = NULL;
                ppd->sdma_head_phys = 0;
        }

        if (ppd->sdma_descq) {
                dma_free_coherent(&dd->pcidev->dev,
                                  ppd->sdma_descq_cnt * sizeof(u64[2]),
                                  ppd->sdma_descq, ppd->sdma_descq_phys);
                ppd->sdma_descq = NULL;
                ppd->sdma_descq_phys = 0;
        }
}

static inline void make_sdma_desc(struct qib_pportdata *ppd,
                                  u64 *sdmadesc, u64 addr, u64 dwlen,
                                  u64 dwoffset)
{

        WARN_ON(addr & 3);
        /* SDmaPhyAddr[47:32] */
        sdmadesc[1] = addr >> 32;
        /* SDmaPhyAddr[31:0] */
        sdmadesc[0] = (addr & 0xfffffffcULL) << 32;
        /* SDmaGeneration[1:0] */
        sdmadesc[0] |= (ppd->sdma_generation & 3ULL) <<
                SDMA_DESC_GEN_LSB;
        /* SDmaDwordCount[10:0] */
        sdmadesc[0] |= (dwlen & 0x7ffULL) << SDMA_DESC_COUNT_LSB;
        /* SDmaBufOffset[12:2] */
        sdmadesc[0] |= dwoffset & 0x7ffULL;
}

/* sdma_lock must be held */
int qib_sdma_make_progress(struct qib_pportdata *ppd)
{
        struct list_head *lp = NULL;
        struct qib_sdma_txreq *txp = NULL;
        struct qib_devdata *dd = ppd->dd;
        int progress = 0;
        u16 hwhead;
        u16 idx = 0;

        hwhead = dd->f_sdma_gethead(ppd);

        /* The reason for some of the complexity of this code is that
         * not all descriptors have corresponding txps.  So, we have to
         * be able to skip over descs until we wander into the range of
         * the next txp on the list.
         */

        if (!list_empty(&ppd->sdma_activelist)) {
                lp = ppd->sdma_activelist.next;
                txp = list_entry(lp, struct qib_sdma_txreq, list);
                idx = txp->start_idx;
        }

        while (ppd->sdma_descq_head != hwhead) {
                /* if desc is part of this txp, unmap if needed */
                if (txp && (txp->flags & QIB_SDMA_TXREQ_F_FREEDESC) &&
                    (idx == ppd->sdma_descq_head)) {
                        unmap_desc(ppd, ppd->sdma_descq_head);
                        if (++idx == ppd->sdma_descq_cnt)
                                idx = 0;
                }

                /* increment dequed desc count */
                ppd->sdma_descq_removed++;

                /* advance head, wrap if needed */
                if (++ppd->sdma_descq_head == ppd->sdma_descq_cnt)
                        ppd->sdma_descq_head = 0;

                /* if now past this txp's descs, do the callback */
                if (txp && txp->next_descq_idx == ppd->sdma_descq_head) {
                        /* remove from active list */
                        list_del_init(&txp->list);
                        if (txp->callback)
                                (*txp->callback)(txp, QIB_SDMA_TXREQ_S_OK);
                        /* see if there is another txp */
                        if (list_empty(&ppd->sdma_activelist))
                                txp = NULL;
                        else {
                                lp = ppd->sdma_activelist.next;
                                txp = list_entry(lp, struct qib_sdma_txreq,
                                        list);
                                idx = txp->start_idx;
                        }
                }
                progress = 1;
        }
        if (progress)
                qib_verbs_sdma_desc_avail(ppd, qib_sdma_descq_freecnt(ppd));
        return progress;
}

/*
 * This is called from interrupt context.
 */
void qib_sdma_intr(struct qib_pportdata *ppd)
{
        unsigned long flags;

        spin_lock_irqsave(&ppd->sdma_lock, flags);

        __qib_sdma_intr(ppd);

        spin_unlock_irqrestore(&ppd->sdma_lock, flags);
}

void __qib_sdma_intr(struct qib_pportdata *ppd)
{
        if (__qib_sdma_running(ppd)) {
                qib_sdma_make_progress(ppd);
                if (!list_empty(&ppd->sdma_userpending))
                        qib_user_sdma_send_desc(ppd, &ppd->sdma_userpending);
        }
}

int qib_setup_sdma(struct qib_pportdata *ppd)
{
        struct qib_devdata *dd = ppd->dd;
        unsigned long flags;
        int ret = 0;

        ret = alloc_sdma(ppd);
        if (ret)
                goto bail;

        /* set consistent sdma state */
        ppd->dd->f_sdma_init_early(ppd);
        spin_lock_irqsave(&ppd->sdma_lock, flags);
        sdma_set_state(ppd, qib_sdma_state_s00_hw_down);
        spin_unlock_irqrestore(&ppd->sdma_lock, flags);

        /* set up reference counting */
        kref_init(&ppd->sdma_state.kref);
        init_completion(&ppd->sdma_state.comp);

        ppd->sdma_generation = 0;
        ppd->sdma_descq_head = 0;
        ppd->sdma_descq_removed = 0;
        ppd->sdma_descq_added = 0;

        ppd->sdma_intrequest = 0;
        INIT_LIST_HEAD(&ppd->sdma_userpending);

        INIT_LIST_HEAD(&ppd->sdma_activelist);

        tasklet_init(&ppd->sdma_sw_clean_up_task, sdma_sw_clean_up_task,
                (unsigned long)ppd);

        ret = dd->f_init_sdma_regs(ppd);
        if (ret)
                goto bail_alloc;

        qib_sdma_process_event(ppd, qib_sdma_event_e10_go_hw_start);

        return 0;

bail_alloc:
        qib_teardown_sdma(ppd);
bail:
        return ret;
}

void qib_teardown_sdma(struct qib_pportdata *ppd)
{
        qib_sdma_process_event(ppd, qib_sdma_event_e00_go_hw_down);

        /*
         * This waits for the state machine to exit so it is not
         * necessary to kill the sdma_sw_clean_up_task to make sure
         * it is not running.
         */
        sdma_finalput(&ppd->sdma_state);

        free_sdma(ppd);
}

int qib_sdma_running(struct qib_pportdata *ppd)
{
        unsigned long flags;
        int ret;

        spin_lock_irqsave(&ppd->sdma_lock, flags);
        ret = __qib_sdma_running(ppd);
        spin_unlock_irqrestore(&ppd->sdma_lock, flags);

        return ret;
}

/*
 * Complete a request when sdma not running; likely only request
 * but to simplify the code, always queue it, then process the full
 * activelist.  We process the entire list to ensure that this particular
 * request does get it's callback, but in the correct order.
 * Must be called with sdma_lock held
 */
static void complete_sdma_err_req(struct qib_pportdata *ppd,
                                  struct qib_verbs_txreq *tx)
{
        struct qib_qp_priv *priv = tx->qp->priv;

        atomic_inc(&priv->s_dma_busy);
        /* no sdma descriptors, so no unmap_desc */
        tx->txreq.start_idx = 0;
        tx->txreq.next_descq_idx = 0;
        list_add_tail(&tx->txreq.list, &ppd->sdma_activelist);
        clear_sdma_activelist(ppd);
}

/*
 * This function queues one IB packet onto the send DMA queue per call.
 * The caller is responsible for checking:
 * 1) The number of send DMA descriptor entries is less than the size of
 *    the descriptor queue.
 * 2) The IB SGE addresses and lengths are 32-bit aligned
 *    (except possibly the last SGE's length)
 * 3) The SGE addresses are suitable for passing to dma_map_single().
 */
int qib_sdma_verbs_send(struct qib_pportdata *ppd,
                        struct rvt_sge_state *ss, u32 dwords,
                        struct qib_verbs_txreq *tx)
{
        unsigned long flags;
        struct rvt_sge *sge;
        struct rvt_qp *qp;
        int ret = 0;
        u16 tail;
        __le64 *descqp;
        u64 sdmadesc[2];
        u32 dwoffset;
        dma_addr_t addr;
        struct qib_qp_priv *priv;

        spin_lock_irqsave(&ppd->sdma_lock, flags);

retry:
        if (unlikely(!__qib_sdma_running(ppd))) {
                complete_sdma_err_req(ppd, tx);
                goto unlock;
        }

        if (tx->txreq.sg_count > qib_sdma_descq_freecnt(ppd)) {
                if (qib_sdma_make_progress(ppd))
                        goto retry;
                if (ppd->dd->flags & QIB_HAS_SDMA_TIMEOUT)
                        ppd->dd->f_sdma_set_desc_cnt(ppd,
                                        ppd->sdma_descq_cnt / 2);
                goto busy;
        }

        dwoffset = tx->hdr_dwords;
        make_sdma_desc(ppd, sdmadesc, (u64) tx->txreq.addr, dwoffset, 0);

        sdmadesc[0] |= SDMA_DESC_FIRST;
        if (tx->txreq.flags & QIB_SDMA_TXREQ_F_USELARGEBUF)
                sdmadesc[0] |= SDMA_DESC_USE_LARGE_BUF;

        /* write to the descq */
        tail = ppd->sdma_descq_tail;
        descqp = &ppd->sdma_descq[tail].qw[0];
        *descqp++ = cpu_to_le64(sdmadesc[0]);
        *descqp++ = cpu_to_le64(sdmadesc[1]);

        /* increment the tail */
        if (++tail == ppd->sdma_descq_cnt) {
                tail = 0;
                descqp = &ppd->sdma_descq[0].qw[0];
                ++ppd->sdma_generation;
        }

        tx->txreq.start_idx = tail;

        sge = &ss->sge;
        while (dwords) {
                u32 dw;
                u32 len;

                len = dwords << 2;
                if (len > sge->length)
                        len = sge->length;
                if (len > sge->sge_length)
                        len = sge->sge_length;
                BUG_ON(len == 0);
                dw = (len + 3) >> 2;
                addr = dma_map_single(&ppd->dd->pcidev->dev, sge->vaddr,
                                      dw << 2, DMA_TO_DEVICE);
                if (dma_mapping_error(&ppd->dd->pcidev->dev, addr))
                        goto unmap;
                sdmadesc[0] = 0;
                make_sdma_desc(ppd, sdmadesc, (u64) addr, dw, dwoffset);
                /* SDmaUseLargeBuf has to be set in every descriptor */
                if (tx->txreq.flags & QIB_SDMA_TXREQ_F_USELARGEBUF)
                        sdmadesc[0] |= SDMA_DESC_USE_LARGE_BUF;
                /* write to the descq */
                *descqp++ = cpu_to_le64(sdmadesc[0]);
                *descqp++ = cpu_to_le64(sdmadesc[1]);

                /* increment the tail */
                if (++tail == ppd->sdma_descq_cnt) {
                        tail = 0;
                        descqp = &ppd->sdma_descq[0].qw[0];
                        ++ppd->sdma_generation;
                }
                sge->vaddr += len;
                sge->length -= len;
                sge->sge_length -= len;
                if (sge->sge_length == 0) {
                        if (--ss->num_sge)
                                *sge = *ss->sg_list++;
                } else if (sge->length == 0 && sge->mr->lkey) {
                        if (++sge->n >= RVT_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;
                }

                dwoffset += dw;
                dwords -= dw;
        }

        if (!tail)
                descqp = &ppd->sdma_descq[ppd->sdma_descq_cnt].qw[0];
        descqp -= 2;
        descqp[0] |= cpu_to_le64(SDMA_DESC_LAST);
        if (tx->txreq.flags & QIB_SDMA_TXREQ_F_HEADTOHOST)
                descqp[0] |= cpu_to_le64(SDMA_DESC_DMA_HEAD);
        if (tx->txreq.flags & QIB_SDMA_TXREQ_F_INTREQ)
                descqp[0] |= cpu_to_le64(SDMA_DESC_INTR);
        priv = tx->qp->priv;
        atomic_inc(&priv->s_dma_busy);
        tx->txreq.next_descq_idx = tail;
        ppd->dd->f_sdma_update_tail(ppd, tail);
        ppd->sdma_descq_added += tx->txreq.sg_count;
        list_add_tail(&tx->txreq.list, &ppd->sdma_activelist);
        goto unlock;

unmap:
        for (;;) {
                if (!tail)
                        tail = ppd->sdma_descq_cnt - 1;
                else
                        tail--;
                if (tail == ppd->sdma_descq_tail)
                        break;
                unmap_desc(ppd, tail);
        }
        qp = tx->qp;
        priv = qp->priv;
        qib_put_txreq(tx);
        spin_lock(&qp->r_lock);
        spin_lock(&qp->s_lock);
        if (qp->ibqp.qp_type == IB_QPT_RC) {
                /* XXX what about error sending RDMA read responses? */
                if (ib_rvt_state_ops[qp->state] & RVT_PROCESS_RECV_OK)
                        rvt_error_qp(qp, IB_WC_GENERAL_ERR);
        } else if (qp->s_wqe)
                qib_send_complete(qp, qp->s_wqe, IB_WC_GENERAL_ERR);
        spin_unlock(&qp->s_lock);
        spin_unlock(&qp->r_lock);
        /* return zero to process the next send work request */
        goto unlock;

busy:
        qp = tx->qp;
        priv = qp->priv;
        spin_lock(&qp->s_lock);
        if (ib_rvt_state_ops[qp->state] & RVT_PROCESS_RECV_OK) {
                struct qib_ibdev *dev;

                /*
                 * If we couldn't queue the DMA request, save the info
                 * and try again later rather than destroying the
                 * buffer and undoing the side effects of the copy.
                 */
                tx->ss = ss;
                tx->dwords = dwords;
                priv->s_tx = tx;
                dev = &ppd->dd->verbs_dev;
                spin_lock(&dev->rdi.pending_lock);
                if (list_empty(&priv->iowait)) {
                        struct qib_ibport *ibp;

                        ibp = &ppd->ibport_data;
                        ibp->rvp.n_dmawait++;
                        qp->s_flags |= RVT_S_WAIT_DMA_DESC;
                        list_add_tail(&priv->iowait, &dev->dmawait);
                }
                spin_unlock(&dev->rdi.pending_lock);
                qp->s_flags &= ~RVT_S_BUSY;
                spin_unlock(&qp->s_lock);
                ret = -EBUSY;
        } else {
                spin_unlock(&qp->s_lock);
                qib_put_txreq(tx);
        }
unlock:
        spin_unlock_irqrestore(&ppd->sdma_lock, flags);
        return ret;
}

/*
 * sdma_lock should be acquired before calling this routine
 */
void dump_sdma_state(struct qib_pportdata *ppd)
{
        struct qib_sdma_desc *descq;
        struct qib_sdma_txreq *txp, *txpnext;
        __le64 *descqp;
        u64 desc[2];
        u64 addr;
        u16 gen, dwlen, dwoffset;
        u16 head, tail, cnt;

        head = ppd->sdma_descq_head;
        tail = ppd->sdma_descq_tail;
        cnt = qib_sdma_descq_freecnt(ppd);
        descq = ppd->sdma_descq;

        qib_dev_porterr(ppd->dd, ppd->port,
                "SDMA ppd->sdma_descq_head: %u\n", head);
        qib_dev_porterr(ppd->dd, ppd->port,
                "SDMA ppd->sdma_descq_tail: %u\n", tail);
        qib_dev_porterr(ppd->dd, ppd->port,
                "SDMA sdma_descq_freecnt: %u\n", cnt);

        /* print info for each entry in the descriptor queue */
        while (head != tail) {
                char flags[6] = { 'x', 'x', 'x', 'x', 'x', 0 };

                descqp = &descq[head].qw[0];
                desc[0] = le64_to_cpu(descqp[0]);
                desc[1] = le64_to_cpu(descqp[1]);
                flags[0] = (desc[0] & 1<<15) ? 'I' : '-';
                flags[1] = (desc[0] & 1<<14) ? 'L' : 'S';
                flags[2] = (desc[0] & 1<<13) ? 'H' : '-';
                flags[3] = (desc[0] & 1<<12) ? 'F' : '-';
                flags[4] = (desc[0] & 1<<11) ? 'L' : '-';
                addr = (desc[1] << 32) | ((desc[0] >> 32) & 0xfffffffcULL);
                gen = (desc[0] >> 30) & 3ULL;
                dwlen = (desc[0] >> 14) & (0x7ffULL << 2);
                dwoffset = (desc[0] & 0x7ffULL) << 2;
                qib_dev_porterr(ppd->dd, ppd->port,
                        "SDMA sdmadesc[%u]: flags:%s addr:0x%016llx gen:%u len:%u bytes offset:%u bytes\n",
                         head, flags, addr, gen, dwlen, dwoffset);
                if (++head == ppd->sdma_descq_cnt)
                        head = 0;
        }

        /* print dma descriptor indices from the TX requests */
        list_for_each_entry_safe(txp, txpnext, &ppd->sdma_activelist,
                                 list)
                qib_dev_porterr(ppd->dd, ppd->port,
                        "SDMA txp->start_idx: %u txp->next_descq_idx: %u\n",
                        txp->start_idx, txp->next_descq_idx);
}

void qib_sdma_process_event(struct qib_pportdata *ppd,
        enum qib_sdma_events event)
{
        unsigned long flags;

        spin_lock_irqsave(&ppd->sdma_lock, flags);

        __qib_sdma_process_event(ppd, event);

        if (ppd->sdma_state.current_state == qib_sdma_state_s99_running)
                qib_verbs_sdma_desc_avail(ppd, qib_sdma_descq_freecnt(ppd));

        spin_unlock_irqrestore(&ppd->sdma_lock, flags);
}

void __qib_sdma_process_event(struct qib_pportdata *ppd,
        enum qib_sdma_events event)
{
        struct qib_sdma_state *ss = &ppd->sdma_state;

        switch (ss->current_state) {
        case qib_sdma_state_s00_hw_down:
                switch (event) {
                case qib_sdma_event_e00_go_hw_down:
                        break;
                case qib_sdma_event_e30_go_running:
                        /*
                         * If down, but running requested (usually result
                         * of link up, then we need to start up.
                         * This can happen when hw down is requested while
                         * bringing the link up with traffic active on
                         * 7220, e.g. */
                        ss->go_s99_running = 1;
                        /* fall through -- and start dma engine */
                case qib_sdma_event_e10_go_hw_start:
                        /* This reference means the state machine is started */
                        sdma_get(&ppd->sdma_state);
                        sdma_set_state(ppd,
                                       qib_sdma_state_s10_hw_start_up_wait);
                        break;
                case qib_sdma_event_e20_hw_started:
                        break;
                case qib_sdma_event_e40_sw_cleaned:
                        sdma_sw_tear_down(ppd);
                        break;
                case qib_sdma_event_e50_hw_cleaned:
                        break;
                case qib_sdma_event_e60_hw_halted:
                        break;
                case qib_sdma_event_e70_go_idle:
                        break;
                case qib_sdma_event_e7220_err_halted:
                        break;
                case qib_sdma_event_e7322_err_halted:
                        break;
                case qib_sdma_event_e90_timer_tick:
                        break;
                }
                break;

        case qib_sdma_state_s10_hw_start_up_wait:
                switch (event) {
                case qib_sdma_event_e00_go_hw_down:
                        sdma_set_state(ppd, qib_sdma_state_s00_hw_down);
                        sdma_sw_tear_down(ppd);
                        break;
                case qib_sdma_event_e10_go_hw_start:
                        break;
                case qib_sdma_event_e20_hw_started:
                        sdma_set_state(ppd, ss->go_s99_running ?
                                       qib_sdma_state_s99_running :
                                       qib_sdma_state_s20_idle);
                        break;
                case qib_sdma_event_e30_go_running:
                        ss->go_s99_running = 1;
                        break;
                case qib_sdma_event_e40_sw_cleaned:
                        break;
                case qib_sdma_event_e50_hw_cleaned:
                        break;
                case qib_sdma_event_e60_hw_halted:
                        break;
                case qib_sdma_event_e70_go_idle:
                        ss->go_s99_running = 0;
                        break;
                case qib_sdma_event_e7220_err_halted:
                        break;
                case qib_sdma_event_e7322_err_halted:
                        break;
                case qib_sdma_event_e90_timer_tick:
                        break;
                }
                break;

        case qib_sdma_state_s20_idle:
                switch (event) {
                case qib_sdma_event_e00_go_hw_down:
                        sdma_set_state(ppd, qib_sdma_state_s00_hw_down);
                        sdma_sw_tear_down(ppd);
                        break;
                case qib_sdma_event_e10_go_hw_start:
                        break;
                case qib_sdma_event_e20_hw_started:
                        break;
                case qib_sdma_event_e30_go_running:
                        sdma_set_state(ppd, qib_sdma_state_s99_running);
                        ss->go_s99_running = 1;
                        break;
                case qib_sdma_event_e40_sw_cleaned:
                        break;
                case qib_sdma_event_e50_hw_cleaned:
                        break;
                case qib_sdma_event_e60_hw_halted:
                        break;
                case qib_sdma_event_e70_go_idle:
                        break;
                case qib_sdma_event_e7220_err_halted:
                        break;
                case qib_sdma_event_e7322_err_halted:
                        break;
                case qib_sdma_event_e90_timer_tick:
                        break;
                }
                break;

        case qib_sdma_state_s30_sw_clean_up_wait:
                switch (event) {
                case qib_sdma_event_e00_go_hw_down:
                        sdma_set_state(ppd, qib_sdma_state_s00_hw_down);
                        break;
                case qib_sdma_event_e10_go_hw_start:
                        break;
                case qib_sdma_event_e20_hw_started:
                        break;
                case qib_sdma_event_e30_go_running:
                        ss->go_s99_running = 1;
                        break;
                case qib_sdma_event_e40_sw_cleaned:
                        sdma_set_state(ppd,
                                       qib_sdma_state_s10_hw_start_up_wait);
                        sdma_hw_start_up(ppd);
                        break;
                case qib_sdma_event_e50_hw_cleaned:
                        break;
                case qib_sdma_event_e60_hw_halted:
                        break;
                case qib_sdma_event_e70_go_idle:
                        ss->go_s99_running = 0;
                        break;
                case qib_sdma_event_e7220_err_halted:
                        break;
                case qib_sdma_event_e7322_err_halted:
                        break;
                case qib_sdma_event_e90_timer_tick:
                        break;
                }
                break;

        case qib_sdma_state_s40_hw_clean_up_wait:
                switch (event) {
                case qib_sdma_event_e00_go_hw_down:
                        sdma_set_state(ppd, qib_sdma_state_s00_hw_down);
                        sdma_start_sw_clean_up(ppd);
                        break;
                case qib_sdma_event_e10_go_hw_start:
                        break;
                case qib_sdma_event_e20_hw_started:
                        break;
                case qib_sdma_event_e30_go_running:
                        ss->go_s99_running = 1;
                        break;
                case qib_sdma_event_e40_sw_cleaned:
                        break;
                case qib_sdma_event_e50_hw_cleaned:
                        sdma_set_state(ppd,
                                       qib_sdma_state_s30_sw_clean_up_wait);
                        sdma_start_sw_clean_up(ppd);
                        break;
                case qib_sdma_event_e60_hw_halted:
                        break;
                case qib_sdma_event_e70_go_idle:
                        ss->go_s99_running = 0;
                        break;
                case qib_sdma_event_e7220_err_halted:
                        break;
                case qib_sdma_event_e7322_err_halted:
                        break;
                case qib_sdma_event_e90_timer_tick:
                        break;
                }
                break;

        case qib_sdma_state_s50_hw_halt_wait:
                switch (event) {
                case qib_sdma_event_e00_go_hw_down:
                        sdma_set_state(ppd, qib_sdma_state_s00_hw_down);
                        sdma_start_sw_clean_up(ppd);
                        break;
                case qib_sdma_event_e10_go_hw_start:
                        break;
                case qib_sdma_event_e20_hw_started:
                        break;
                case qib_sdma_event_e30_go_running:
                        ss->go_s99_running = 1;
                        break;
                case qib_sdma_event_e40_sw_cleaned:
                        break;
                case qib_sdma_event_e50_hw_cleaned:
                        break;
                case qib_sdma_event_e60_hw_halted:
                        sdma_set_state(ppd,
                                       qib_sdma_state_s40_hw_clean_up_wait);
                        ppd->dd->f_sdma_hw_clean_up(ppd);
                        break;
                case qib_sdma_event_e70_go_idle:
                        ss->go_s99_running = 0;
                        break;
                case qib_sdma_event_e7220_err_halted:
                        break;
                case qib_sdma_event_e7322_err_halted:
                        break;
                case qib_sdma_event_e90_timer_tick:
                        break;
                }
                break;

        case qib_sdma_state_s99_running:
                switch (event) {
                case qib_sdma_event_e00_go_hw_down:
                        sdma_set_state(ppd, qib_sdma_state_s00_hw_down);
                        sdma_start_sw_clean_up(ppd);
                        break;
                case qib_sdma_event_e10_go_hw_start:
                        break;
                case qib_sdma_event_e20_hw_started:
                        break;
                case qib_sdma_event_e30_go_running:
                        break;
                case qib_sdma_event_e40_sw_cleaned:
                        break;
                case qib_sdma_event_e50_hw_cleaned:
                        break;
                case qib_sdma_event_e60_hw_halted:
                        sdma_set_state(ppd,
                                       qib_sdma_state_s30_sw_clean_up_wait);
                        sdma_start_sw_clean_up(ppd);
                        break;
                case qib_sdma_event_e70_go_idle:
                        sdma_set_state(ppd, qib_sdma_state_s50_hw_halt_wait);
                        ss->go_s99_running = 0;
                        break;
                case qib_sdma_event_e7220_err_halted:
                        sdma_set_state(ppd,
                                       qib_sdma_state_s30_sw_clean_up_wait);
                        sdma_start_sw_clean_up(ppd);
                        break;
                case qib_sdma_event_e7322_err_halted:
                        sdma_set_state(ppd, qib_sdma_state_s50_hw_halt_wait);
                        break;
                case qib_sdma_event_e90_timer_tick:
                        break;
                }
                break;
        }

        ss->last_event = event;
}