Merge tag 'clk-fixes-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git...

[mirror_ubuntu-artful-kernel.git] / drivers / staging / rdma / hfi1 / sdma.c

/*
 *
 * This file is provided under a dual BSD/GPLv2 license.  When using or
 * redistributing this file, you may do so under either license.
 *
 * GPL LICENSE SUMMARY
 *
 * Copyright(c) 2015 Intel Corporation.
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of version 2 of the GNU General Public License as
 * published by the Free Software Foundation.
 *
 * This program is distributed in the hope that it will be useful, but
 * WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
 * General Public License for more details.
 *
 * BSD LICENSE
 *
 * Copyright(c) 2015 Intel Corporation.
 *
 * 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.
 *  - Neither the name of Intel Corporation nor the names of its
 *    contributors may be used to endorse or promote products derived
 *    from this software without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
 * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
 * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
 * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
 * OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
 * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
 * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
 * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 *
 */

#include <linux/spinlock.h>
#include <linux/seqlock.h>
#include <linux/netdevice.h>
#include <linux/moduleparam.h>
#include <linux/bitops.h>
#include <linux/timer.h>
#include <linux/vmalloc.h>

#include "hfi.h"
#include "common.h"
#include "qp.h"
#include "sdma.h"
#include "iowait.h"
#include "trace.h"

/* must be a power of 2 >= 64 <= 32768 */
#define SDMA_DESCQ_CNT 1024
#define INVALID_TAIL 0xffff

static uint sdma_descq_cnt = SDMA_DESCQ_CNT;
module_param(sdma_descq_cnt, uint, S_IRUGO);
MODULE_PARM_DESC(sdma_descq_cnt, "Number of SDMA descq entries");

static uint sdma_idle_cnt = 250;
module_param(sdma_idle_cnt, uint, S_IRUGO);
MODULE_PARM_DESC(sdma_idle_cnt, "sdma interrupt idle delay (ns,default 250)");

uint mod_num_sdma;
module_param_named(num_sdma, mod_num_sdma, uint, S_IRUGO);
MODULE_PARM_DESC(num_sdma, "Set max number SDMA engines to use");

#define SDMA_WAIT_BATCH_SIZE 20
/* max wait time for a SDMA engine to indicate it has halted */
#define SDMA_ERR_HALT_TIMEOUT 10 /* ms */
/* all SDMA engine errors that cause a halt */

#define SD(name) SEND_DMA_##name
#define ALL_SDMA_ENG_HALT_ERRS \
        (SD(ENG_ERR_STATUS_SDMA_WRONG_DW_ERR_SMASK) \
        | SD(ENG_ERR_STATUS_SDMA_GEN_MISMATCH_ERR_SMASK) \
        | SD(ENG_ERR_STATUS_SDMA_TOO_LONG_ERR_SMASK) \
        | SD(ENG_ERR_STATUS_SDMA_TAIL_OUT_OF_BOUNDS_ERR_SMASK) \
        | SD(ENG_ERR_STATUS_SDMA_FIRST_DESC_ERR_SMASK) \
        | SD(ENG_ERR_STATUS_SDMA_MEM_READ_ERR_SMASK) \
        | SD(ENG_ERR_STATUS_SDMA_HALT_ERR_SMASK) \
        | SD(ENG_ERR_STATUS_SDMA_LENGTH_MISMATCH_ERR_SMASK) \
        | SD(ENG_ERR_STATUS_SDMA_PACKET_DESC_OVERFLOW_ERR_SMASK) \
        | SD(ENG_ERR_STATUS_SDMA_HEADER_SELECT_ERR_SMASK) \
        | SD(ENG_ERR_STATUS_SDMA_HEADER_ADDRESS_ERR_SMASK) \
        | SD(ENG_ERR_STATUS_SDMA_HEADER_LENGTH_ERR_SMASK) \
        | SD(ENG_ERR_STATUS_SDMA_TIMEOUT_ERR_SMASK) \
        | SD(ENG_ERR_STATUS_SDMA_DESC_TABLE_UNC_ERR_SMASK) \
        | SD(ENG_ERR_STATUS_SDMA_ASSEMBLY_UNC_ERR_SMASK) \
        | SD(ENG_ERR_STATUS_SDMA_PACKET_TRACKING_UNC_ERR_SMASK) \
        | SD(ENG_ERR_STATUS_SDMA_HEADER_STORAGE_UNC_ERR_SMASK) \
        | SD(ENG_ERR_STATUS_SDMA_HEADER_REQUEST_FIFO_UNC_ERR_SMASK))

/* sdma_sendctrl operations */
#define SDMA_SENDCTRL_OP_ENABLE    (1U << 0)
#define SDMA_SENDCTRL_OP_INTENABLE (1U << 1)
#define SDMA_SENDCTRL_OP_HALT      (1U << 2)
#define SDMA_SENDCTRL_OP_CLEANUP   (1U << 3)

/* handle long defines */
#define SDMA_EGRESS_PACKET_OCCUPANCY_SMASK \
SEND_EGRESS_SEND_DMA_STATUS_SDMA_EGRESS_PACKET_OCCUPANCY_SMASK
#define SDMA_EGRESS_PACKET_OCCUPANCY_SHIFT \
SEND_EGRESS_SEND_DMA_STATUS_SDMA_EGRESS_PACKET_OCCUPANCY_SHIFT

static const char * const sdma_state_names[] = {
        [sdma_state_s00_hw_down]                = "s00_HwDown",
        [sdma_state_s10_hw_start_up_halt_wait]  = "s10_HwStartUpHaltWait",
        [sdma_state_s15_hw_start_up_clean_wait] = "s15_HwStartUpCleanWait",
        [sdma_state_s20_idle]                   = "s20_Idle",
        [sdma_state_s30_sw_clean_up_wait]       = "s30_SwCleanUpWait",
        [sdma_state_s40_hw_clean_up_wait]       = "s40_HwCleanUpWait",
        [sdma_state_s50_hw_halt_wait]           = "s50_HwHaltWait",
        [sdma_state_s60_idle_halt_wait]         = "s60_IdleHaltWait",
        [sdma_state_s80_hw_freeze]              = "s80_HwFreeze",
        [sdma_state_s82_freeze_sw_clean]        = "s82_FreezeSwClean",
        [sdma_state_s99_running]                = "s99_Running",
};

static const char * const sdma_event_names[] = {
        [sdma_event_e00_go_hw_down]   = "e00_GoHwDown",
        [sdma_event_e10_go_hw_start]  = "e10_GoHwStart",
        [sdma_event_e15_hw_halt_done] = "e15_HwHaltDone",
        [sdma_event_e25_hw_clean_up_done] = "e25_HwCleanUpDone",
        [sdma_event_e30_go_running]   = "e30_GoRunning",
        [sdma_event_e40_sw_cleaned]   = "e40_SwCleaned",
        [sdma_event_e50_hw_cleaned]   = "e50_HwCleaned",
        [sdma_event_e60_hw_halted]    = "e60_HwHalted",
        [sdma_event_e70_go_idle]      = "e70_GoIdle",
        [sdma_event_e80_hw_freeze]    = "e80_HwFreeze",
        [sdma_event_e81_hw_frozen]    = "e81_HwFrozen",
        [sdma_event_e82_hw_unfreeze]  = "e82_HwUnfreeze",
        [sdma_event_e85_link_down]    = "e85_LinkDown",
        [sdma_event_e90_sw_halted]    = "e90_SwHalted",
};

static const struct sdma_set_state_action sdma_action_table[] = {
        [sdma_state_s00_hw_down] = {
                .go_s99_running_tofalse = 1,
                .op_enable = 0,
                .op_intenable = 0,
                .op_halt = 0,
                .op_cleanup = 0,
        },
        [sdma_state_s10_hw_start_up_halt_wait] = {
                .op_enable = 0,
                .op_intenable = 0,
                .op_halt = 1,
                .op_cleanup = 0,
        },
        [sdma_state_s15_hw_start_up_clean_wait] = {
                .op_enable = 0,
                .op_intenable = 1,
                .op_halt = 0,
                .op_cleanup = 1,
        },
        [sdma_state_s20_idle] = {
                .op_enable = 0,
                .op_intenable = 1,
                .op_halt = 0,
                .op_cleanup = 0,
        },
        [sdma_state_s30_sw_clean_up_wait] = {
                .op_enable = 0,
                .op_intenable = 0,
                .op_halt = 0,
                .op_cleanup = 0,
        },
        [sdma_state_s40_hw_clean_up_wait] = {
                .op_enable = 0,
                .op_intenable = 0,
                .op_halt = 0,
                .op_cleanup = 1,
        },
        [sdma_state_s50_hw_halt_wait] = {
                .op_enable = 0,
                .op_intenable = 0,
                .op_halt = 0,
                .op_cleanup = 0,
        },
        [sdma_state_s60_idle_halt_wait] = {
                .go_s99_running_tofalse = 1,
                .op_enable = 0,
                .op_intenable = 0,
                .op_halt = 1,
                .op_cleanup = 0,
        },
        [sdma_state_s80_hw_freeze] = {
                .op_enable = 0,
                .op_intenable = 0,
                .op_halt = 0,
                .op_cleanup = 0,
        },
        [sdma_state_s82_freeze_sw_clean] = {
                .op_enable = 0,
                .op_intenable = 0,
                .op_halt = 0,
                .op_cleanup = 0,
        },
        [sdma_state_s99_running] = {
                .op_enable = 1,
                .op_intenable = 1,
                .op_halt = 0,
                .op_cleanup = 0,
                .go_s99_running_totrue = 1,
        },
};

#define SDMA_TAIL_UPDATE_THRESH 0x1F

/* declare all statics here rather than keep sorting */
static void sdma_complete(struct kref *);
static void sdma_finalput(struct sdma_state *);
static void sdma_get(struct sdma_state *);
static void sdma_hw_clean_up_task(unsigned long);
static void sdma_put(struct sdma_state *);
static void sdma_set_state(struct sdma_engine *, enum sdma_states);
static void sdma_start_hw_clean_up(struct sdma_engine *);
static void sdma_start_sw_clean_up(struct sdma_engine *);
static void sdma_sw_clean_up_task(unsigned long);
static void sdma_sendctrl(struct sdma_engine *, unsigned);
static void init_sdma_regs(struct sdma_engine *, u32, uint);
static void sdma_process_event(
        struct sdma_engine *sde,
        enum sdma_events event);
static void __sdma_process_event(
        struct sdma_engine *sde,
        enum sdma_events event);
static void dump_sdma_state(struct sdma_engine *sde);
static void sdma_make_progress(struct sdma_engine *sde, u64 status);
static void sdma_desc_avail(struct sdma_engine *sde, unsigned avail);
static void sdma_flush_descq(struct sdma_engine *sde);

/**
 * sdma_state_name() - return state string from enum
 * @state: state
 */
static const char *sdma_state_name(enum sdma_states state)
{
        return sdma_state_names[state];
}

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

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

        complete(&ss->comp);
}

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

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

static inline void write_sde_csr(
        struct sdma_engine *sde,
        u32 offset0,
        u64 value)
{
        write_kctxt_csr(sde->dd, sde->this_idx, offset0, value);
}

static inline u64 read_sde_csr(
        struct sdma_engine *sde,
        u32 offset0)
{
        return read_kctxt_csr(sde->dd, sde->this_idx, offset0);
}

/*
 * sdma_wait_for_packet_egress() - wait for the VL FIFO occupancy for
 * sdma engine 'sde' to drop to 0.
 */
static void sdma_wait_for_packet_egress(struct sdma_engine *sde,
                                        int pause)
{
        u64 off = 8 * sde->this_idx;
        struct hfi1_devdata *dd = sde->dd;
        int lcnt = 0;

        while (1) {
                u64 reg = read_csr(dd, off + SEND_EGRESS_SEND_DMA_STATUS);

                reg &= SDMA_EGRESS_PACKET_OCCUPANCY_SMASK;
                reg >>= SDMA_EGRESS_PACKET_OCCUPANCY_SHIFT;
                if (reg == 0)
                        break;
                if (lcnt++ > 100) {
                        dd_dev_err(dd, "%s: engine %u timeout waiting for packets to egress, remaining count %u\n",
                                  __func__, sde->this_idx, (u32)reg);
                        break;
                }
                udelay(1);
        }
}

/*
 * sdma_wait() - wait for packet egress to complete for all SDMA engines,
 * and pause for credit return.
 */
void sdma_wait(struct hfi1_devdata *dd)
{
        int i;

        for (i = 0; i < dd->num_sdma; i++) {
                struct sdma_engine *sde = &dd->per_sdma[i];

                sdma_wait_for_packet_egress(sde, 0);
        }
}

static inline void sdma_set_desc_cnt(struct sdma_engine *sde, unsigned cnt)
{
        u64 reg;

        if (!(sde->dd->flags & HFI1_HAS_SDMA_TIMEOUT))
                return;
        reg = cnt;
        reg &= SD(DESC_CNT_CNT_MASK);
        reg <<= SD(DESC_CNT_CNT_SHIFT);
        write_sde_csr(sde, SD(DESC_CNT), reg);
}

/*
 * Complete all the sdma requests with a SDMA_TXREQ_S_ABORTED status
 *
 * Depending on timing there can be txreqs in two places:
 * - in the descq ring
 * - in the flush list
 *
 * To avoid ordering issues the descq ring needs to be flushed
 * first followed by the flush list.
 *
 * This routine is called from two places
 * - From a work queue item
 * - Directly from the state machine just before setting the
 *   state to running
 *
 * Must be called with head_lock held
 *
 */
static void sdma_flush(struct sdma_engine *sde)
{
        struct sdma_txreq *txp, *txp_next;
        LIST_HEAD(flushlist);

        /* flush from head to tail */
        sdma_flush_descq(sde);
        spin_lock(&sde->flushlist_lock);
        /* copy flush list */
        list_for_each_entry_safe(txp, txp_next, &sde->flushlist, list) {
                list_del_init(&txp->list);
                list_add_tail(&txp->list, &flushlist);
        }
        spin_unlock(&sde->flushlist_lock);
        /* flush from flush list */
        list_for_each_entry_safe(txp, txp_next, &flushlist, list) {
                int drained = 0;
                /* protect against complete modifying */
                struct iowait *wait = txp->wait;

                list_del_init(&txp->list);
#ifdef CONFIG_HFI1_DEBUG_SDMA_ORDER
                trace_hfi1_sdma_out_sn(sde, txp->sn);
                if (WARN_ON_ONCE(sde->head_sn != txp->sn))
                        dd_dev_err(sde->dd, "expected %llu got %llu\n",
                                sde->head_sn, txp->sn);
                sde->head_sn++;
#endif
                sdma_txclean(sde->dd, txp);
                if (wait)
                        drained = atomic_dec_and_test(&wait->sdma_busy);
                if (txp->complete)
                        (*txp->complete)(txp, SDMA_TXREQ_S_ABORTED, drained);
                if (wait && drained)
                        iowait_drain_wakeup(wait);
        }
}

/*
 * Fields a work request for flushing the descq ring
 * and the flush list
 *
 * If the engine has been brought to running during
 * the scheduling delay, the flush is ignored, assuming
 * that the process of bringing the engine to running
 * would have done this flush prior to going to running.
 *
 */
static void sdma_field_flush(struct work_struct *work)
{
        unsigned long flags;
        struct sdma_engine *sde =
                container_of(work, struct sdma_engine, flush_worker);

        write_seqlock_irqsave(&sde->head_lock, flags);
        if (!__sdma_running(sde))
                sdma_flush(sde);
        write_sequnlock_irqrestore(&sde->head_lock, flags);
}

static void sdma_err_halt_wait(struct work_struct *work)
{
        struct sdma_engine *sde = container_of(work, struct sdma_engine,
                                                err_halt_worker);
        u64 statuscsr;
        unsigned long timeout;

        timeout = jiffies + msecs_to_jiffies(SDMA_ERR_HALT_TIMEOUT);
        while (1) {
                statuscsr = read_sde_csr(sde, SD(STATUS));
                statuscsr &= SD(STATUS_ENG_HALTED_SMASK);
                if (statuscsr)
                        break;
                if (time_after(jiffies, timeout)) {
                        dd_dev_err(sde->dd,
                                "SDMA engine %d - timeout waiting for engine to halt\n",
                                sde->this_idx);
                        /*
                         * Continue anyway.  This could happen if there was
                         * an uncorrectable error in the wrong spot.
                         */
                        break;
                }
                usleep_range(80, 120);
        }

        sdma_process_event(sde, sdma_event_e15_hw_halt_done);
}

static void sdma_start_err_halt_wait(struct sdma_engine *sde)
{
        schedule_work(&sde->err_halt_worker);
}


static void sdma_err_progress_check_schedule(struct sdma_engine *sde)
{
        if (!is_bx(sde->dd) && HFI1_CAP_IS_KSET(SDMA_AHG)) {

                unsigned index;
                struct hfi1_devdata *dd = sde->dd;

                for (index = 0; index < dd->num_sdma; index++) {
                        struct sdma_engine *curr_sdma = &dd->per_sdma[index];

                        if (curr_sdma != sde)
                                curr_sdma->progress_check_head =
                                                        curr_sdma->descq_head;
                }
                dd_dev_err(sde->dd,
                           "SDMA engine %d - check scheduled\n",
                                sde->this_idx);
                mod_timer(&sde->err_progress_check_timer, jiffies + 10);
        }
}

static void sdma_err_progress_check(unsigned long data)
{
        unsigned index;
        struct sdma_engine *sde = (struct sdma_engine *)data;

        dd_dev_err(sde->dd, "SDE progress check event\n");
        for (index = 0; index < sde->dd->num_sdma; index++) {
                struct sdma_engine *curr_sde = &sde->dd->per_sdma[index];
                unsigned long flags;

                /* check progress on each engine except the current one */
                if (curr_sde == sde)
                        continue;
                /*
                 * We must lock interrupts when acquiring sde->lock,
                 * to avoid a deadlock if interrupt triggers and spins on
                 * the same lock on same CPU
                 */
                spin_lock_irqsave(&curr_sde->tail_lock, flags);
                write_seqlock(&curr_sde->head_lock);

                /* skip non-running queues */
                if (curr_sde->state.current_state != sdma_state_s99_running) {
                        write_sequnlock(&curr_sde->head_lock);
                        spin_unlock_irqrestore(&curr_sde->tail_lock, flags);
                        continue;
                }

                if ((curr_sde->descq_head != curr_sde->descq_tail) &&
                    (curr_sde->descq_head ==
                                curr_sde->progress_check_head))
                        __sdma_process_event(curr_sde,
                                             sdma_event_e90_sw_halted);
                write_sequnlock(&curr_sde->head_lock);
                spin_unlock_irqrestore(&curr_sde->tail_lock, flags);
        }
        schedule_work(&sde->err_halt_worker);
}

static void sdma_hw_clean_up_task(unsigned long opaque)
{
        struct sdma_engine *sde = (struct sdma_engine *) opaque;
        u64 statuscsr;

        while (1) {
#ifdef CONFIG_SDMA_VERBOSITY
                dd_dev_err(sde->dd, "CONFIG SDMA(%u) %s:%d %s()\n",
                           sde->this_idx, slashstrip(__FILE__), __LINE__,
                        __func__);
#endif
                statuscsr = read_sde_csr(sde, SD(STATUS));
                statuscsr &= SD(STATUS_ENG_CLEANED_UP_SMASK);
                if (statuscsr)
                        break;
                udelay(10);
        }

        sdma_process_event(sde, sdma_event_e25_hw_clean_up_done);
}

static inline struct sdma_txreq *get_txhead(struct sdma_engine *sde)
{
        smp_read_barrier_depends(); /* see sdma_update_tail() */
        return sde->tx_ring[sde->tx_head & sde->sdma_mask];
}

/*
 * flush ring for recovery
 */
static void sdma_flush_descq(struct sdma_engine *sde)
{
        u16 head, tail;
        int progress = 0;
        struct sdma_txreq *txp = get_txhead(sde);

        /* 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.
         */
        head = sde->descq_head & sde->sdma_mask;
        tail = sde->descq_tail & sde->sdma_mask;
        while (head != tail) {
                /* advance head, wrap if needed */
                head = ++sde->descq_head & sde->sdma_mask;
                /* if now past this txp's descs, do the callback */
                if (txp && txp->next_descq_idx == head) {
                        int drained = 0;
                        /* protect against complete modifying */
                        struct iowait *wait = txp->wait;

                        /* remove from list */
                        sde->tx_ring[sde->tx_head++ & sde->sdma_mask] = NULL;
                        if (wait)
                                drained = atomic_dec_and_test(&wait->sdma_busy);
#ifdef CONFIG_HFI1_DEBUG_SDMA_ORDER
                        trace_hfi1_sdma_out_sn(sde, txp->sn);
                        if (WARN_ON_ONCE(sde->head_sn != txp->sn))
                                dd_dev_err(sde->dd, "expected %llu got %llu\n",
                                        sde->head_sn, txp->sn);
                        sde->head_sn++;
#endif
                        sdma_txclean(sde->dd, txp);
                        trace_hfi1_sdma_progress(sde, head, tail, txp);
                        if (txp->complete)
                                (*txp->complete)(
                                        txp,
                                        SDMA_TXREQ_S_ABORTED,
                                        drained);
                        if (wait && drained)
                                iowait_drain_wakeup(wait);
                        /* see if there is another txp */
                        txp = get_txhead(sde);
                }
                progress++;
        }
        if (progress)
                sdma_desc_avail(sde, sdma_descq_freecnt(sde));
}

static void sdma_sw_clean_up_task(unsigned long opaque)
{
        struct sdma_engine *sde = (struct sdma_engine *) opaque;
        unsigned long flags;

        spin_lock_irqsave(&sde->tail_lock, flags);
        write_seqlock(&sde->head_lock);

        /*
         * 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.
         */


        /*
         * In the error clean up sequence, software clean must be called
         * before the hardware clean so we can use the hardware head in
         * the progress routine.  A hardware clean or SPC unfreeze will
         * reset the hardware head.
         *
         * Process all retired requests. The progress routine will use the
         * latest physical hardware head - we are not running so speed does
         * not matter.
         */
        sdma_make_progress(sde, 0);

        sdma_flush(sde);

        /*
         * Reset our notion of head and tail.
         * Note that the HW registers have been reset via an earlier
         * clean up.
         */
        sde->descq_tail = 0;
        sde->descq_head = 0;
        sde->desc_avail = sdma_descq_freecnt(sde);
        *sde->head_dma = 0;

        __sdma_process_event(sde, sdma_event_e40_sw_cleaned);

        write_sequnlock(&sde->head_lock);
        spin_unlock_irqrestore(&sde->tail_lock, flags);
}

static void sdma_sw_tear_down(struct sdma_engine *sde)
{
        struct sdma_state *ss = &sde->state;

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

        /* stop waiting for all unfreeze events to complete */
        atomic_set(&sde->dd->sdma_unfreeze_count, -1);
        wake_up_interruptible(&sde->dd->sdma_unfreeze_wq);
}

static void sdma_start_hw_clean_up(struct sdma_engine *sde)
{
        tasklet_hi_schedule(&sde->sdma_hw_clean_up_task);
}

static void sdma_start_sw_clean_up(struct sdma_engine *sde)
{
        tasklet_hi_schedule(&sde->sdma_sw_clean_up_task);
}

static void sdma_set_state(struct sdma_engine *sde,
        enum sdma_states next_state)
{
        struct sdma_state *ss = &sde->state;
        const struct sdma_set_state_action *action = sdma_action_table;
        unsigned op = 0;

        trace_hfi1_sdma_state(
                sde,
                sdma_state_names[ss->current_state],
                sdma_state_names[next_state]);

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

        if (ss->previous_state != sdma_state_s99_running
                && next_state == sdma_state_s99_running)
                sdma_flush(sde);

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

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

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

        if (action[next_state].op_cleanup)
                op |= SDMA_SENDCTRL_OP_CLEANUP;

        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;
        sdma_sendctrl(sde, ss->current_op);
}

/**
 * sdma_get_descq_cnt() - called when device probed
 *
 * Return a validated descq count.
 *
 * This is currently only used in the verbs initialization to build the tx
 * list.
 *
 * This will probably be deleted in favor of a more scalable approach to
 * alloc tx's.
 *
 */
u16 sdma_get_descq_cnt(void)
{
        u16 count = sdma_descq_cnt;

        if (!count)
                return SDMA_DESCQ_CNT;
        /* count must be a power of 2 greater than 64 and less than
         * 32768.   Otherwise return default.
         */
        if (!is_power_of_2(count))
                return SDMA_DESCQ_CNT;
        if (count < 64 || count > 32768)
                return SDMA_DESCQ_CNT;
        return count;
}
/**
 * sdma_select_engine_vl() - select sdma engine
 * @dd: devdata
 * @selector: a spreading factor
 * @vl: this vl
 *
 *
 * This function returns an engine based on the selector and a vl.  The
 * mapping fields are protected by RCU.
 */
struct sdma_engine *sdma_select_engine_vl(
        struct hfi1_devdata *dd,
        u32 selector,
        u8 vl)
{
        struct sdma_vl_map *m;
        struct sdma_map_elem *e;
        struct sdma_engine *rval;

        if (WARN_ON(vl > 8))
                return NULL;

        rcu_read_lock();
        m = rcu_dereference(dd->sdma_map);
        if (unlikely(!m)) {
                rcu_read_unlock();
                return NULL;
        }
        e = m->map[vl & m->mask];
        rval = e->sde[selector & e->mask];
        rcu_read_unlock();

        trace_hfi1_sdma_engine_select(dd, selector, vl, rval->this_idx);
        return rval;
}

/**
 * sdma_select_engine_sc() - select sdma engine
 * @dd: devdata
 * @selector: a spreading factor
 * @sc5: the 5 bit sc
 *
 *
 * This function returns an engine based on the selector and an sc.
 */
struct sdma_engine *sdma_select_engine_sc(
        struct hfi1_devdata *dd,
        u32 selector,
        u8 sc5)
{
        u8 vl = sc_to_vlt(dd, sc5);

        return sdma_select_engine_vl(dd, selector, vl);
}

/*
 * Free the indicated map struct
 */
static void sdma_map_free(struct sdma_vl_map *m)
{
        int i;

        for (i = 0; m && i < m->actual_vls; i++)
                kfree(m->map[i]);
        kfree(m);
}

/*
 * Handle RCU callback
 */
static void sdma_map_rcu_callback(struct rcu_head *list)
{
        struct sdma_vl_map *m = container_of(list, struct sdma_vl_map, list);

        sdma_map_free(m);
}

/**
 * sdma_map_init - called when # vls change
 * @dd: hfi1_devdata
 * @port: port number
 * @num_vls: number of vls
 * @vl_engines: per vl engine mapping (optional)
 *
 * This routine changes the mapping based on the number of vls.
 *
 * vl_engines is used to specify a non-uniform vl/engine loading. NULL
 * implies auto computing the loading and giving each VLs a uniform
 * distribution of engines per VL.
 *
 * The auto algorithm computes the sde_per_vl and the number of extra
 * engines.  Any extra engines are added from the last VL on down.
 *
 * rcu locking is used here to control access to the mapping fields.
 *
 * If either the num_vls or num_sdma are non-power of 2, the array sizes
 * in the struct sdma_vl_map and the struct sdma_map_elem are rounded
 * up to the next highest power of 2 and the first entry is reused
 * in a round robin fashion.
 *
 * If an error occurs the map change is not done and the mapping is
 * not changed.
 *
 */
int sdma_map_init(struct hfi1_devdata *dd, u8 port, u8 num_vls, u8 *vl_engines)
{
        int i, j;
        int extra, sde_per_vl;
        int engine = 0;
        u8 lvl_engines[OPA_MAX_VLS];
        struct sdma_vl_map *oldmap, *newmap;

        if (!(dd->flags & HFI1_HAS_SEND_DMA))
                return 0;

        if (!vl_engines) {
                /* truncate divide */
                sde_per_vl = dd->num_sdma / num_vls;
                /* extras */
                extra = dd->num_sdma % num_vls;
                vl_engines = lvl_engines;
                /* add extras from last vl down */
                for (i = num_vls - 1; i >= 0; i--, extra--)
                        vl_engines[i] = sde_per_vl + (extra > 0 ? 1 : 0);
        }
        /* build new map */
        newmap = kzalloc(
                sizeof(struct sdma_vl_map) +
                        roundup_pow_of_two(num_vls) *
                        sizeof(struct sdma_map_elem *),
                GFP_KERNEL);
        if (!newmap)
                goto bail;
        newmap->actual_vls = num_vls;
        newmap->vls = roundup_pow_of_two(num_vls);
        newmap->mask = (1 << ilog2(newmap->vls)) - 1;
        for (i = 0; i < newmap->vls; i++) {
                /* save for wrap around */
                int first_engine = engine;

                if (i < newmap->actual_vls) {
                        int sz = roundup_pow_of_two(vl_engines[i]);

                        /* only allocate once */
                        newmap->map[i] = kzalloc(
                                sizeof(struct sdma_map_elem) +
                                        sz * sizeof(struct sdma_engine *),
                                GFP_KERNEL);
                        if (!newmap->map[i])
                                goto bail;
                        newmap->map[i]->mask = (1 << ilog2(sz)) - 1;
                        /* assign engines */
                        for (j = 0; j < sz; j++) {
                                newmap->map[i]->sde[j] =
                                        &dd->per_sdma[engine];
                                if (++engine >= first_engine + vl_engines[i])
                                        /* wrap back to first engine */
                                        engine = first_engine;
                        }
                } else {
                        /* just re-use entry without allocating */
                        newmap->map[i] = newmap->map[i % num_vls];
                }
                engine = first_engine + vl_engines[i];
        }
        /* newmap in hand, save old map */
        spin_lock_irq(&dd->sde_map_lock);
        oldmap = rcu_dereference_protected(dd->sdma_map,
                        lockdep_is_held(&dd->sde_map_lock));

        /* publish newmap */
        rcu_assign_pointer(dd->sdma_map, newmap);

        spin_unlock_irq(&dd->sde_map_lock);
        /* success, free any old map after grace period */
        if (oldmap)
                call_rcu(&oldmap->list, sdma_map_rcu_callback);
        return 0;
bail:
        /* free any partial allocation */
        sdma_map_free(newmap);
        return -ENOMEM;
}

/*
 * Clean up allocated memory.
 *
 * This routine is can be called regardless of the success of sdma_init()
 *
 */
static void sdma_clean(struct hfi1_devdata *dd, size_t num_engines)
{
        size_t i;
        struct sdma_engine *sde;

        if (dd->sdma_pad_dma) {
                dma_free_coherent(&dd->pcidev->dev, 4,
                                  (void *)dd->sdma_pad_dma,
                                  dd->sdma_pad_phys);
                dd->sdma_pad_dma = NULL;
                dd->sdma_pad_phys = 0;
        }
        if (dd->sdma_heads_dma) {
                dma_free_coherent(&dd->pcidev->dev, dd->sdma_heads_size,
                                  (void *)dd->sdma_heads_dma,
                                  dd->sdma_heads_phys);
                dd->sdma_heads_dma = NULL;
                dd->sdma_heads_phys = 0;
        }
        for (i = 0; dd->per_sdma && i < num_engines; ++i) {
                sde = &dd->per_sdma[i];

                sde->head_dma = NULL;
                sde->head_phys = 0;

                if (sde->descq) {
                        dma_free_coherent(
                                &dd->pcidev->dev,
                                sde->descq_cnt * sizeof(u64[2]),
                                sde->descq,
                                sde->descq_phys
                        );
                        sde->descq = NULL;
                        sde->descq_phys = 0;
                }
                if (is_vmalloc_addr(sde->tx_ring))
                        vfree(sde->tx_ring);
                else
                        kfree(sde->tx_ring);
                sde->tx_ring = NULL;
        }
        spin_lock_irq(&dd->sde_map_lock);
        kfree(rcu_access_pointer(dd->sdma_map));
        RCU_INIT_POINTER(dd->sdma_map, NULL);
        spin_unlock_irq(&dd->sde_map_lock);
        synchronize_rcu();
        kfree(dd->per_sdma);
        dd->per_sdma = NULL;
}

/**
 * sdma_init() - called when device probed
 * @dd: hfi1_devdata
 * @port: port number (currently only zero)
 *
 * sdma_init initializes the specified number of engines.
 *
 * The code initializes each sde, its csrs.  Interrupts
 * are not required to be enabled.
 *
 * Returns:
 * 0 - success, -errno on failure
 */
int sdma_init(struct hfi1_devdata *dd, u8 port)
{
        unsigned this_idx;
        struct sdma_engine *sde;
        u16 descq_cnt;
        void *curr_head;
        struct hfi1_pportdata *ppd = dd->pport + port;
        u32 per_sdma_credits;
        uint idle_cnt = sdma_idle_cnt;
        size_t num_engines = dd->chip_sdma_engines;

        if (!HFI1_CAP_IS_KSET(SDMA)) {
                HFI1_CAP_CLEAR(SDMA_AHG);
                return 0;
        }
        if (mod_num_sdma &&
                /* can't exceed chip support */
                mod_num_sdma <= dd->chip_sdma_engines &&
                /* count must be >= vls */
                mod_num_sdma >= num_vls)
                num_engines = mod_num_sdma;

        dd_dev_info(dd, "SDMA mod_num_sdma: %u\n", mod_num_sdma);
        dd_dev_info(dd, "SDMA chip_sdma_engines: %u\n", dd->chip_sdma_engines);
        dd_dev_info(dd, "SDMA chip_sdma_mem_size: %u\n",
                dd->chip_sdma_mem_size);

        per_sdma_credits =
                dd->chip_sdma_mem_size/(num_engines * SDMA_BLOCK_SIZE);

        /* set up freeze waitqueue */
        init_waitqueue_head(&dd->sdma_unfreeze_wq);
        atomic_set(&dd->sdma_unfreeze_count, 0);

        descq_cnt = sdma_get_descq_cnt();
        dd_dev_info(dd, "SDMA engines %zu descq_cnt %u\n",
                num_engines, descq_cnt);

        /* alloc memory for array of send engines */
        dd->per_sdma = kcalloc(num_engines, sizeof(*dd->per_sdma), GFP_KERNEL);
        if (!dd->per_sdma)
                return -ENOMEM;

        idle_cnt = ns_to_cclock(dd, idle_cnt);
        /* Allocate memory for SendDMA descriptor FIFOs */
        for (this_idx = 0; this_idx < num_engines; ++this_idx) {
                sde = &dd->per_sdma[this_idx];
                sde->dd = dd;
                sde->ppd = ppd;
                sde->this_idx = this_idx;
                sde->descq_cnt = descq_cnt;
                sde->desc_avail = sdma_descq_freecnt(sde);
                sde->sdma_shift = ilog2(descq_cnt);
                sde->sdma_mask = (1 << sde->sdma_shift) - 1;
                sde->descq_full_count = 0;

                /* Create a mask for all 3 chip interrupt sources */
                sde->imask = (u64)1 << (0*TXE_NUM_SDMA_ENGINES + this_idx)
                        | (u64)1 << (1*TXE_NUM_SDMA_ENGINES + this_idx)
                        | (u64)1 << (2*TXE_NUM_SDMA_ENGINES + this_idx);
                /* Create a mask specifically for sdma_idle */
                sde->idle_mask =
                        (u64)1 << (2*TXE_NUM_SDMA_ENGINES + this_idx);
                /* Create a mask specifically for sdma_progress */
                sde->progress_mask =
                        (u64)1 << (TXE_NUM_SDMA_ENGINES + this_idx);
                spin_lock_init(&sde->tail_lock);
                seqlock_init(&sde->head_lock);
                spin_lock_init(&sde->senddmactrl_lock);
                spin_lock_init(&sde->flushlist_lock);
                /* insure there is always a zero bit */
                sde->ahg_bits = 0xfffffffe00000000ULL;

                sdma_set_state(sde, sdma_state_s00_hw_down);

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

                INIT_LIST_HEAD(&sde->flushlist);
                INIT_LIST_HEAD(&sde->dmawait);

                sde->tail_csr =
                        get_kctxt_csr_addr(dd, this_idx, SD(TAIL));

                if (idle_cnt)
                        dd->default_desc1 =
                                SDMA_DESC1_HEAD_TO_HOST_FLAG;
                else
                        dd->default_desc1 =
                                SDMA_DESC1_INT_REQ_FLAG;

                tasklet_init(&sde->sdma_hw_clean_up_task, sdma_hw_clean_up_task,
                        (unsigned long)sde);

                tasklet_init(&sde->sdma_sw_clean_up_task, sdma_sw_clean_up_task,
                        (unsigned long)sde);
                INIT_WORK(&sde->err_halt_worker, sdma_err_halt_wait);
                INIT_WORK(&sde->flush_worker, sdma_field_flush);

                sde->progress_check_head = 0;

                init_timer(&sde->err_progress_check_timer);
                sde->err_progress_check_timer.function =
                                                sdma_err_progress_check;
                sde->err_progress_check_timer.data = (unsigned long)sde;

                sde->descq = dma_zalloc_coherent(
                        &dd->pcidev->dev,
                        descq_cnt * sizeof(u64[2]),
                        &sde->descq_phys,
                        GFP_KERNEL
                );
                if (!sde->descq)
                        goto bail;
                sde->tx_ring =
                        kcalloc(descq_cnt, sizeof(struct sdma_txreq *),
                                GFP_KERNEL);
                if (!sde->tx_ring)
                        sde->tx_ring =
                                vzalloc(
                                        sizeof(struct sdma_txreq *) *
                                        descq_cnt);
                if (!sde->tx_ring)
                        goto bail;
        }

        dd->sdma_heads_size = L1_CACHE_BYTES * num_engines;
        /* Allocate memory for DMA of head registers to memory */
        dd->sdma_heads_dma = dma_zalloc_coherent(
                &dd->pcidev->dev,
                dd->sdma_heads_size,
                &dd->sdma_heads_phys,
                GFP_KERNEL
        );
        if (!dd->sdma_heads_dma) {
                dd_dev_err(dd, "failed to allocate SendDMA head memory\n");
                goto bail;
        }

        /* Allocate memory for pad */
        dd->sdma_pad_dma = dma_zalloc_coherent(
                &dd->pcidev->dev,
                sizeof(u32),
                &dd->sdma_pad_phys,
                GFP_KERNEL
        );
        if (!dd->sdma_pad_dma) {
                dd_dev_err(dd, "failed to allocate SendDMA pad memory\n");
                goto bail;
        }

        /* assign each engine to different cacheline and init registers */
        curr_head = (void *)dd->sdma_heads_dma;
        for (this_idx = 0; this_idx < num_engines; ++this_idx) {
                unsigned long phys_offset;

                sde = &dd->per_sdma[this_idx];

                sde->head_dma = curr_head;
                curr_head += L1_CACHE_BYTES;
                phys_offset = (unsigned long)sde->head_dma -
                              (unsigned long)dd->sdma_heads_dma;
                sde->head_phys = dd->sdma_heads_phys + phys_offset;
                init_sdma_regs(sde, per_sdma_credits, idle_cnt);
        }
        dd->flags |= HFI1_HAS_SEND_DMA;
        dd->flags |= idle_cnt ? HFI1_HAS_SDMA_TIMEOUT : 0;
        dd->num_sdma = num_engines;
        if (sdma_map_init(dd, port, ppd->vls_operational, NULL))
                goto bail;
        dd_dev_info(dd, "SDMA num_sdma: %u\n", dd->num_sdma);
        return 0;

bail:
        sdma_clean(dd, num_engines);
        return -ENOMEM;
}

/**
 * sdma_all_running() - called when the link goes up
 * @dd: hfi1_devdata
 *
 * This routine moves all engines to the running state.
 */
void sdma_all_running(struct hfi1_devdata *dd)
{
        struct sdma_engine *sde;
        unsigned int i;

        /* move all engines to running */
        for (i = 0; i < dd->num_sdma; ++i) {
                sde = &dd->per_sdma[i];
                sdma_process_event(sde, sdma_event_e30_go_running);
        }
}

/**
 * sdma_all_idle() - called when the link goes down
 * @dd: hfi1_devdata
 *
 * This routine moves all engines to the idle state.
 */
void sdma_all_idle(struct hfi1_devdata *dd)
{
        struct sdma_engine *sde;
        unsigned int i;

        /* idle all engines */
        for (i = 0; i < dd->num_sdma; ++i) {
                sde = &dd->per_sdma[i];
                sdma_process_event(sde, sdma_event_e70_go_idle);
        }
}

/**
 * sdma_start() - called to kick off state processing for all engines
 * @dd: hfi1_devdata
 *
 * This routine is for kicking off the state processing for all required
 * sdma engines.  Interrupts need to be working at this point.
 *
 */
void sdma_start(struct hfi1_devdata *dd)
{
        unsigned i;
        struct sdma_engine *sde;

        /* kick off the engines state processing */
        for (i = 0; i < dd->num_sdma; ++i) {
                sde = &dd->per_sdma[i];
                sdma_process_event(sde, sdma_event_e10_go_hw_start);
        }
}

/**
 * sdma_exit() - used when module is removed
 * @dd: hfi1_devdata
 */
void sdma_exit(struct hfi1_devdata *dd)
{
        unsigned this_idx;
        struct sdma_engine *sde;

        for (this_idx = 0; dd->per_sdma && this_idx < dd->num_sdma;
                        ++this_idx) {

                sde = &dd->per_sdma[this_idx];
                if (!list_empty(&sde->dmawait))
                        dd_dev_err(dd, "sde %u: dmawait list not empty!\n",
                                sde->this_idx);
                sdma_process_event(sde, sdma_event_e00_go_hw_down);

                del_timer_sync(&sde->err_progress_check_timer);

                /*
                 * 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(&sde->state);
        }
        sdma_clean(dd, dd->num_sdma);
}

/*
 * unmap the indicated descriptor
 */
static inline void sdma_unmap_desc(
        struct hfi1_devdata *dd,
        struct sdma_desc *descp)
{
        switch (sdma_mapping_type(descp)) {
        case SDMA_MAP_SINGLE:
                dma_unmap_single(
                        &dd->pcidev->dev,
                        sdma_mapping_addr(descp),
                        sdma_mapping_len(descp),
                        DMA_TO_DEVICE);
                break;
        case SDMA_MAP_PAGE:
                dma_unmap_page(
                        &dd->pcidev->dev,
                        sdma_mapping_addr(descp),
                        sdma_mapping_len(descp),
                        DMA_TO_DEVICE);
                break;
        }
}

/*
 * return the mode as indicated by the first
 * descriptor in the tx.
 */
static inline u8 ahg_mode(struct sdma_txreq *tx)
{
        return (tx->descp[0].qw[1] & SDMA_DESC1_HEADER_MODE_SMASK)
                >> SDMA_DESC1_HEADER_MODE_SHIFT;
}

/**
 * sdma_txclean() - clean tx of mappings, descp *kmalloc's
 * @dd: hfi1_devdata for unmapping
 * @tx: tx request to clean
 *
 * This is used in the progress routine to clean the tx or
 * by the ULP to toss an in-process tx build.
 *
 * The code can be called multiple times without issue.
 *
 */
void sdma_txclean(
        struct hfi1_devdata *dd,
        struct sdma_txreq *tx)
{
        u16 i;

        if (tx->num_desc) {
                u8 skip = 0, mode = ahg_mode(tx);

                /* unmap first */
                sdma_unmap_desc(dd, &tx->descp[0]);
                /* determine number of AHG descriptors to skip */
                if (mode > SDMA_AHG_APPLY_UPDATE1)
                        skip = mode >> 1;
                for (i = 1 + skip; i < tx->num_desc; i++)
                        sdma_unmap_desc(dd, &tx->descp[i]);
                tx->num_desc = 0;
        }
        kfree(tx->coalesce_buf);
        tx->coalesce_buf = NULL;
        /* kmalloc'ed descp */
        if (unlikely(tx->desc_limit > ARRAY_SIZE(tx->descs))) {
                tx->desc_limit = ARRAY_SIZE(tx->descs);
                kfree(tx->descp);
        }
}

static inline u16 sdma_gethead(struct sdma_engine *sde)
{
        struct hfi1_devdata *dd = sde->dd;
        int use_dmahead;
        u16 hwhead;

#ifdef CONFIG_SDMA_VERBOSITY
        dd_dev_err(sde->dd, "CONFIG SDMA(%u) %s:%d %s()\n",
                   sde->this_idx, slashstrip(__FILE__), __LINE__, __func__);
#endif

retry:
        use_dmahead = HFI1_CAP_IS_KSET(USE_SDMA_HEAD) && __sdma_running(sde) &&
                                        (dd->flags & HFI1_HAS_SDMA_TIMEOUT);
        hwhead = use_dmahead ?
                (u16) le64_to_cpu(*sde->head_dma) :
                (u16) read_sde_csr(sde, SD(HEAD));

        if (unlikely(HFI1_CAP_IS_KSET(SDMA_HEAD_CHECK))) {
                u16 cnt;
                u16 swtail;
                u16 swhead;
                int sane;

                swhead = sde->descq_head & sde->sdma_mask;
                /* this code is really bad for cache line trading */
                swtail = ACCESS_ONCE(sde->descq_tail) & sde->sdma_mask;
                cnt = sde->descq_cnt;

                if (swhead < swtail)
                        /* not wrapped */
                        sane = (hwhead >= swhead) & (hwhead <= swtail);
                else if (swhead > swtail)
                        /* wrapped around */
                        sane = ((hwhead >= swhead) && (hwhead < cnt)) ||
                                (hwhead <= swtail);
                else
                        /* empty */
                        sane = (hwhead == swhead);

                if (unlikely(!sane)) {
                        dd_dev_err(dd, "SDMA(%u) bad head (%s) hwhd=%hu swhd=%hu swtl=%hu cnt=%hu\n",
                                sde->this_idx,
                                use_dmahead ? "dma" : "kreg",
                                hwhead, swhead, swtail, cnt);
                        if (use_dmahead) {
                                /* try one more time, using csr */
                                use_dmahead = 0;
                                goto retry;
                        }
                        /* proceed as if no progress */
                        hwhead = swhead;
                }
        }
        return hwhead;
}

/*
 * This is called when there are send DMA descriptors that might be
 * available.
 *
 * This is called with head_lock held.
 */
static void sdma_desc_avail(struct sdma_engine *sde, unsigned avail)
{
        struct iowait *wait, *nw;
        struct iowait *waits[SDMA_WAIT_BATCH_SIZE];
        unsigned i, n = 0, seq;
        struct sdma_txreq *stx;
        struct hfi1_ibdev *dev = &sde->dd->verbs_dev;

#ifdef CONFIG_SDMA_VERBOSITY
        dd_dev_err(sde->dd, "CONFIG SDMA(%u) %s:%d %s()\n", sde->this_idx,
                   slashstrip(__FILE__), __LINE__, __func__);
        dd_dev_err(sde->dd, "avail: %u\n", avail);
#endif

        do {
                seq = read_seqbegin(&dev->iowait_lock);
                if (!list_empty(&sde->dmawait)) {
                        /* at least one item */
                        write_seqlock(&dev->iowait_lock);
                        /* Harvest waiters wanting DMA descriptors */
                        list_for_each_entry_safe(
                                        wait,
                                        nw,
                                        &sde->dmawait,
                                        list) {
                                u16 num_desc = 0;

                                if (!wait->wakeup)
                                        continue;
                                if (n == ARRAY_SIZE(waits))
                                        break;
                                if (!list_empty(&wait->tx_head)) {
                                        stx = list_first_entry(
                                                &wait->tx_head,
                                                struct sdma_txreq,
                                                list);
                                        num_desc = stx->num_desc;
                                }
                                if (num_desc > avail)
                                        break;
                                avail -= num_desc;
                                list_del_init(&wait->list);
                                waits[n++] = wait;
                        }
                        write_sequnlock(&dev->iowait_lock);
                        break;
                }
        } while (read_seqretry(&dev->iowait_lock, seq));

        for (i = 0; i < n; i++)
                waits[i]->wakeup(waits[i], SDMA_AVAIL_REASON);
}

/* head_lock must be held */
static void sdma_make_progress(struct sdma_engine *sde, u64 status)
{
        struct sdma_txreq *txp = NULL;
        int progress = 0;
        u16 hwhead, swhead, swtail;
        int idle_check_done = 0;

        hwhead = sdma_gethead(sde);

        /* 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.
         */

retry:
        txp = get_txhead(sde);
        swhead = sde->descq_head & sde->sdma_mask;
        trace_hfi1_sdma_progress(sde, hwhead, swhead, txp);
        while (swhead != hwhead) {
                /* advance head, wrap if needed */
                swhead = ++sde->descq_head & sde->sdma_mask;

                /* if now past this txp's descs, do the callback */
                if (txp && txp->next_descq_idx == swhead) {
                        int drained = 0;
                        /* protect against complete modifying */
                        struct iowait *wait = txp->wait;

                        /* remove from list */
                        sde->tx_ring[sde->tx_head++ & sde->sdma_mask] = NULL;
                        if (wait)
                                drained = atomic_dec_and_test(&wait->sdma_busy);
#ifdef CONFIG_HFI1_DEBUG_SDMA_ORDER
                        trace_hfi1_sdma_out_sn(sde, txp->sn);
                        if (WARN_ON_ONCE(sde->head_sn != txp->sn))
                                dd_dev_err(sde->dd, "expected %llu got %llu\n",
                                        sde->head_sn, txp->sn);
                        sde->head_sn++;
#endif
                        sdma_txclean(sde->dd, txp);
                        if (txp->complete)
                                (*txp->complete)(
                                        txp,
                                        SDMA_TXREQ_S_OK,
                                        drained);
                        if (wait && drained)
                                iowait_drain_wakeup(wait);
                        /* see if there is another txp */
                        txp = get_txhead(sde);
                }
                trace_hfi1_sdma_progress(sde, hwhead, swhead, txp);
                progress++;
        }

        /*
         * The SDMA idle interrupt is not guaranteed to be ordered with respect
         * to updates to the the dma_head location in host memory. The head
         * value read might not be fully up to date. If there are pending
         * descriptors and the SDMA idle interrupt fired then read from the
         * CSR SDMA head instead to get the latest value from the hardware.
         * The hardware SDMA head should be read at most once in this invocation
         * of sdma_make_progress(..) which is ensured by idle_check_done flag
         */
        if ((status & sde->idle_mask) && !idle_check_done) {
                swtail = ACCESS_ONCE(sde->descq_tail) & sde->sdma_mask;
                if (swtail != hwhead) {
                        hwhead = (u16)read_sde_csr(sde, SD(HEAD));
                        idle_check_done = 1;
                        goto retry;
                }
        }

        sde->last_status = status;
        if (progress)
                sdma_desc_avail(sde, sdma_descq_freecnt(sde));
}

/*
 * sdma_engine_interrupt() - interrupt handler for engine
 * @sde: sdma engine
 * @status: sdma interrupt reason
 *
 * Status is a mask of the 3 possible interrupts for this engine.  It will
 * contain bits _only_ for this SDMA engine.  It will contain at least one
 * bit, it may contain more.
 */
void sdma_engine_interrupt(struct sdma_engine *sde, u64 status)
{
        trace_hfi1_sdma_engine_interrupt(sde, status);
        write_seqlock(&sde->head_lock);
        sdma_set_desc_cnt(sde, sde->descq_cnt / 2);
        sdma_make_progress(sde, status);
        write_sequnlock(&sde->head_lock);
}

/**
 * sdma_engine_error() - error handler for engine
 * @sde: sdma engine
 * @status: sdma interrupt reason
 */
void sdma_engine_error(struct sdma_engine *sde, u64 status)
{
        unsigned long flags;

#ifdef CONFIG_SDMA_VERBOSITY
        dd_dev_err(sde->dd, "CONFIG SDMA(%u) error status 0x%llx state %s\n",
                   sde->this_idx,
                   (unsigned long long)status,
                   sdma_state_names[sde->state.current_state]);
#endif
        spin_lock_irqsave(&sde->tail_lock, flags);
        write_seqlock(&sde->head_lock);
        if (status & ALL_SDMA_ENG_HALT_ERRS)
                __sdma_process_event(sde, sdma_event_e60_hw_halted);
        if (status & ~SD(ENG_ERR_STATUS_SDMA_HALT_ERR_SMASK)) {
                dd_dev_err(sde->dd,
                        "SDMA (%u) engine error: 0x%llx state %s\n",
                        sde->this_idx,
                        (unsigned long long)status,
                        sdma_state_names[sde->state.current_state]);
                dump_sdma_state(sde);
        }
        write_sequnlock(&sde->head_lock);
        spin_unlock_irqrestore(&sde->tail_lock, flags);
}

static void sdma_sendctrl(struct sdma_engine *sde, unsigned op)
{
        u64 set_senddmactrl = 0;
        u64 clr_senddmactrl = 0;
        unsigned long flags;

#ifdef CONFIG_SDMA_VERBOSITY
        dd_dev_err(sde->dd, "CONFIG SDMA(%u) senddmactrl E=%d I=%d H=%d C=%d\n",
                   sde->this_idx,
                   (op & SDMA_SENDCTRL_OP_ENABLE) ? 1 : 0,
                   (op & SDMA_SENDCTRL_OP_INTENABLE) ? 1 : 0,
                   (op & SDMA_SENDCTRL_OP_HALT) ? 1 : 0,
                   (op & SDMA_SENDCTRL_OP_CLEANUP) ? 1 : 0);
#endif

        if (op & SDMA_SENDCTRL_OP_ENABLE)
                set_senddmactrl |= SD(CTRL_SDMA_ENABLE_SMASK);
        else
                clr_senddmactrl |= SD(CTRL_SDMA_ENABLE_SMASK);

        if (op & SDMA_SENDCTRL_OP_INTENABLE)
                set_senddmactrl |= SD(CTRL_SDMA_INT_ENABLE_SMASK);
        else
                clr_senddmactrl |= SD(CTRL_SDMA_INT_ENABLE_SMASK);

        if (op & SDMA_SENDCTRL_OP_HALT)
                set_senddmactrl |= SD(CTRL_SDMA_HALT_SMASK);
        else
                clr_senddmactrl |= SD(CTRL_SDMA_HALT_SMASK);

        spin_lock_irqsave(&sde->senddmactrl_lock, flags);

        sde->p_senddmactrl |= set_senddmactrl;
        sde->p_senddmactrl &= ~clr_senddmactrl;

        if (op & SDMA_SENDCTRL_OP_CLEANUP)
                write_sde_csr(sde, SD(CTRL),
                        sde->p_senddmactrl |
                        SD(CTRL_SDMA_CLEANUP_SMASK));
        else
                write_sde_csr(sde, SD(CTRL), sde->p_senddmactrl);

        spin_unlock_irqrestore(&sde->senddmactrl_lock, flags);

#ifdef CONFIG_SDMA_VERBOSITY
        sdma_dumpstate(sde);
#endif
}

static void sdma_setlengen(struct sdma_engine *sde)
{
#ifdef CONFIG_SDMA_VERBOSITY
        dd_dev_err(sde->dd, "CONFIG SDMA(%u) %s:%d %s()\n",
                   sde->this_idx, slashstrip(__FILE__), __LINE__, __func__);
#endif

        /*
         * Set SendDmaLenGen and clear-then-set the MSB of the generation
         * count to enable generation checking and load the internal
         * generation counter.
         */
        write_sde_csr(sde, SD(LEN_GEN),
                (sde->descq_cnt/64) << SD(LEN_GEN_LENGTH_SHIFT)
        );
        write_sde_csr(sde, SD(LEN_GEN),
                ((sde->descq_cnt/64) << SD(LEN_GEN_LENGTH_SHIFT))
                | (4ULL << SD(LEN_GEN_GENERATION_SHIFT))
        );
}

static inline void sdma_update_tail(struct sdma_engine *sde, u16 tail)
{
        /* Commit writes to memory and advance the tail on the chip */
        smp_wmb(); /* see get_txhead() */
        writeq(tail, sde->tail_csr);
}

/*
 * This is called when changing to state s10_hw_start_up_halt_wait as
 * a result of send buffer errors or send DMA descriptor errors.
 */
static void sdma_hw_start_up(struct sdma_engine *sde)
{
        u64 reg;

#ifdef CONFIG_SDMA_VERBOSITY
        dd_dev_err(sde->dd, "CONFIG SDMA(%u) %s:%d %s()\n",
                   sde->this_idx, slashstrip(__FILE__), __LINE__, __func__);
#endif

        sdma_setlengen(sde);
        sdma_update_tail(sde, 0); /* Set SendDmaTail */
        *sde->head_dma = 0;

        reg = SD(ENG_ERR_CLEAR_SDMA_HEADER_REQUEST_FIFO_UNC_ERR_MASK) <<
              SD(ENG_ERR_CLEAR_SDMA_HEADER_REQUEST_FIFO_UNC_ERR_SHIFT);
        write_sde_csr(sde, SD(ENG_ERR_CLEAR), reg);
}

#define CLEAR_STATIC_RATE_CONTROL_SMASK(r) \
(r &= ~SEND_DMA_CHECK_ENABLE_DISALLOW_PBC_STATIC_RATE_CONTROL_SMASK)

#define SET_STATIC_RATE_CONTROL_SMASK(r) \
(r |= SEND_DMA_CHECK_ENABLE_DISALLOW_PBC_STATIC_RATE_CONTROL_SMASK)
/*
 * set_sdma_integrity
 *
 * Set the SEND_DMA_CHECK_ENABLE register for send DMA engine 'sde'.
 */
static void set_sdma_integrity(struct sdma_engine *sde)
{
        struct hfi1_devdata *dd = sde->dd;
        u64 reg;

        if (unlikely(HFI1_CAP_IS_KSET(NO_INTEGRITY)))
                return;

        reg = hfi1_pkt_base_sdma_integrity(dd);

        if (HFI1_CAP_IS_KSET(STATIC_RATE_CTRL))
                CLEAR_STATIC_RATE_CONTROL_SMASK(reg);
        else
                SET_STATIC_RATE_CONTROL_SMASK(reg);

        write_sde_csr(sde, SD(CHECK_ENABLE), reg);
}


static void init_sdma_regs(
        struct sdma_engine *sde,
        u32 credits,
        uint idle_cnt)
{
        u8 opval, opmask;
#ifdef CONFIG_SDMA_VERBOSITY
        struct hfi1_devdata *dd = sde->dd;

        dd_dev_err(dd, "CONFIG SDMA(%u) %s:%d %s()\n",
                   sde->this_idx, slashstrip(__FILE__), __LINE__, __func__);
#endif

        write_sde_csr(sde, SD(BASE_ADDR), sde->descq_phys);
        sdma_setlengen(sde);
        sdma_update_tail(sde, 0); /* Set SendDmaTail */
        write_sde_csr(sde, SD(RELOAD_CNT), idle_cnt);
        write_sde_csr(sde, SD(DESC_CNT), 0);
        write_sde_csr(sde, SD(HEAD_ADDR), sde->head_phys);
        write_sde_csr(sde, SD(MEMORY),
                ((u64)credits <<
                        SD(MEMORY_SDMA_MEMORY_CNT_SHIFT)) |
                ((u64)(credits * sde->this_idx) <<
                        SD(MEMORY_SDMA_MEMORY_INDEX_SHIFT)));
        write_sde_csr(sde, SD(ENG_ERR_MASK), ~0ull);
        set_sdma_integrity(sde);
        opmask = OPCODE_CHECK_MASK_DISABLED;
        opval = OPCODE_CHECK_VAL_DISABLED;
        write_sde_csr(sde, SD(CHECK_OPCODE),
                (opmask << SEND_CTXT_CHECK_OPCODE_MASK_SHIFT) |
                (opval << SEND_CTXT_CHECK_OPCODE_VALUE_SHIFT));
}

#ifdef CONFIG_SDMA_VERBOSITY

#define sdma_dumpstate_helper0(reg) do { \
                csr = read_csr(sde->dd, reg); \
                dd_dev_err(sde->dd, "%36s     0x%016llx\n", #reg, csr); \
        } while (0)

#define sdma_dumpstate_helper(reg) do { \
                csr = read_sde_csr(sde, reg); \
                dd_dev_err(sde->dd, "%36s[%02u] 0x%016llx\n", \
                        #reg, sde->this_idx, csr); \
        } while (0)

#define sdma_dumpstate_helper2(reg) do { \
                csr = read_csr(sde->dd, reg + (8 * i)); \
                dd_dev_err(sde->dd, "%33s_%02u     0x%016llx\n", \
                                #reg, i, csr); \
        } while (0)

void sdma_dumpstate(struct sdma_engine *sde)
{
        u64 csr;
        unsigned i;

        sdma_dumpstate_helper(SD(CTRL));
        sdma_dumpstate_helper(SD(STATUS));
        sdma_dumpstate_helper0(SD(ERR_STATUS));
        sdma_dumpstate_helper0(SD(ERR_MASK));
        sdma_dumpstate_helper(SD(ENG_ERR_STATUS));
        sdma_dumpstate_helper(SD(ENG_ERR_MASK));

        for (i = 0; i < CCE_NUM_INT_CSRS; ++i) {
                sdma_dumpstate_helper2(CCE_INT_STATUS);
                sdma_dumpstate_helper2(CCE_INT_MASK);
                sdma_dumpstate_helper2(CCE_INT_BLOCKED);
        }

        sdma_dumpstate_helper(SD(TAIL));
        sdma_dumpstate_helper(SD(HEAD));
        sdma_dumpstate_helper(SD(PRIORITY_THLD));
        sdma_dumpstate_helper(SD(IDLE_CNT));
        sdma_dumpstate_helper(SD(RELOAD_CNT));
        sdma_dumpstate_helper(SD(DESC_CNT));
        sdma_dumpstate_helper(SD(DESC_FETCHED_CNT));
        sdma_dumpstate_helper(SD(MEMORY));
        sdma_dumpstate_helper0(SD(ENGINES));
        sdma_dumpstate_helper0(SD(MEM_SIZE));
        /* sdma_dumpstate_helper(SEND_EGRESS_SEND_DMA_STATUS);  */
        sdma_dumpstate_helper(SD(BASE_ADDR));
        sdma_dumpstate_helper(SD(LEN_GEN));
        sdma_dumpstate_helper(SD(HEAD_ADDR));
        sdma_dumpstate_helper(SD(CHECK_ENABLE));
        sdma_dumpstate_helper(SD(CHECK_VL));
        sdma_dumpstate_helper(SD(CHECK_JOB_KEY));
        sdma_dumpstate_helper(SD(CHECK_PARTITION_KEY));
        sdma_dumpstate_helper(SD(CHECK_SLID));
        sdma_dumpstate_helper(SD(CHECK_OPCODE));
}
#endif

static void dump_sdma_state(struct sdma_engine *sde)
{
        struct hw_sdma_desc *descq;
        struct hw_sdma_desc *descqp;
        u64 desc[2];
        u64 addr;
        u8 gen;
        u16 len;
        u16 head, tail, cnt;

        head = sde->descq_head & sde->sdma_mask;
        tail = sde->descq_tail & sde->sdma_mask;
        cnt = sdma_descq_freecnt(sde);
        descq = sde->descq;

        dd_dev_err(sde->dd,
                "SDMA (%u) descq_head: %u descq_tail: %u freecnt: %u FLE %d\n",
                sde->this_idx,
                head,
                tail,
                cnt,
                !list_empty(&sde->flushlist));

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

                descqp = &sde->descq[head];
                desc[0] = le64_to_cpu(descqp->qw[0]);
                desc[1] = le64_to_cpu(descqp->qw[1]);
                flags[0] = (desc[1] & SDMA_DESC1_INT_REQ_FLAG) ? 'I' : '-';
                flags[1] = (desc[1] & SDMA_DESC1_HEAD_TO_HOST_FLAG) ?
                                'H' : '-';
                flags[2] = (desc[0] & SDMA_DESC0_FIRST_DESC_FLAG) ? 'F' : '-';
                flags[3] = (desc[0] & SDMA_DESC0_LAST_DESC_FLAG) ? 'L' : '-';
                addr = (desc[0] >> SDMA_DESC0_PHY_ADDR_SHIFT)
                        & SDMA_DESC0_PHY_ADDR_MASK;
                gen = (desc[1] >> SDMA_DESC1_GENERATION_SHIFT)
                        & SDMA_DESC1_GENERATION_MASK;
                len = (desc[0] >> SDMA_DESC0_BYTE_COUNT_SHIFT)
                        & SDMA_DESC0_BYTE_COUNT_MASK;
                dd_dev_err(sde->dd,
                        "SDMA sdmadesc[%u]: flags:%s addr:0x%016llx gen:%u len:%u bytes\n",
                         head, flags, addr, gen, len);
                dd_dev_err(sde->dd,
                        "\tdesc0:0x%016llx desc1 0x%016llx\n",
                         desc[0], desc[1]);
                if (desc[0] & SDMA_DESC0_FIRST_DESC_FLAG)
                        dd_dev_err(sde->dd,
                                "\taidx: %u amode: %u alen: %u\n",
                                (u8)((desc[1] & SDMA_DESC1_HEADER_INDEX_SMASK)
                                        >> SDMA_DESC1_HEADER_INDEX_SHIFT),
                                (u8)((desc[1] & SDMA_DESC1_HEADER_MODE_SMASK)
                                        >> SDMA_DESC1_HEADER_MODE_SHIFT),
                                (u8)((desc[1] & SDMA_DESC1_HEADER_DWS_SMASK)
                                        >> SDMA_DESC1_HEADER_DWS_SHIFT));
                head++;
                head &= sde->sdma_mask;
        }
}

#define SDE_FMT \
        "SDE %u STE %s C 0x%llx S 0x%016llx E 0x%llx T(HW) 0x%llx T(SW) 0x%x H(HW) 0x%llx H(SW) 0x%x H(D) 0x%llx DM 0x%llx GL 0x%llx R 0x%llx LIS 0x%llx AHGI 0x%llx TXT %u TXH %u DT %u DH %u FLNE %d DQF %u SLC 0x%llx\n"
/**
 * sdma_seqfile_dump_sde() - debugfs dump of sde
 * @s: seq file
 * @sde: send dma engine to dump
 *
 * This routine dumps the sde to the indicated seq file.
 */
void sdma_seqfile_dump_sde(struct seq_file *s, struct sdma_engine *sde)
{
        u16 head, tail;
        struct hw_sdma_desc *descqp;
        u64 desc[2];
        u64 addr;
        u8 gen;
        u16 len;

        head = sde->descq_head & sde->sdma_mask;
        tail = ACCESS_ONCE(sde->descq_tail) & sde->sdma_mask;
        seq_printf(s, SDE_FMT, sde->this_idx,
                sdma_state_name(sde->state.current_state),
                (unsigned long long)read_sde_csr(sde, SD(CTRL)),
                (unsigned long long)read_sde_csr(sde, SD(STATUS)),
                (unsigned long long)read_sde_csr(sde,
                        SD(ENG_ERR_STATUS)),
                (unsigned long long)read_sde_csr(sde, SD(TAIL)),
                tail,
                (unsigned long long)read_sde_csr(sde, SD(HEAD)),
                head,
                (unsigned long long)le64_to_cpu(*sde->head_dma),
                (unsigned long long)read_sde_csr(sde, SD(MEMORY)),
                (unsigned long long)read_sde_csr(sde, SD(LEN_GEN)),
                (unsigned long long)read_sde_csr(sde, SD(RELOAD_CNT)),
                (unsigned long long)sde->last_status,
                (unsigned long long)sde->ahg_bits,
                sde->tx_tail,
                sde->tx_head,
                sde->descq_tail,
                sde->descq_head,
                   !list_empty(&sde->flushlist),
                sde->descq_full_count,
                (unsigned long long)read_sde_csr(sde, SEND_DMA_CHECK_SLID));

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

                descqp = &sde->descq[head];
                desc[0] = le64_to_cpu(descqp->qw[0]);
                desc[1] = le64_to_cpu(descqp->qw[1]);
                flags[0] = (desc[1] & SDMA_DESC1_INT_REQ_FLAG) ? 'I' : '-';
                flags[1] = (desc[1] & SDMA_DESC1_HEAD_TO_HOST_FLAG) ?
                                'H' : '-';
                flags[2] = (desc[0] & SDMA_DESC0_FIRST_DESC_FLAG) ? 'F' : '-';
                flags[3] = (desc[0] & SDMA_DESC0_LAST_DESC_FLAG) ? 'L' : '-';
                addr = (desc[0] >> SDMA_DESC0_PHY_ADDR_SHIFT)
                        & SDMA_DESC0_PHY_ADDR_MASK;
                gen = (desc[1] >> SDMA_DESC1_GENERATION_SHIFT)
                        & SDMA_DESC1_GENERATION_MASK;
                len = (desc[0] >> SDMA_DESC0_BYTE_COUNT_SHIFT)
                        & SDMA_DESC0_BYTE_COUNT_MASK;
                seq_printf(s,
                        "\tdesc[%u]: flags:%s addr:0x%016llx gen:%u len:%u bytes\n",
                        head, flags, addr, gen, len);
                if (desc[0] & SDMA_DESC0_FIRST_DESC_FLAG)
                        seq_printf(s, "\t\tahgidx: %u ahgmode: %u\n",
                                (u8)((desc[1] & SDMA_DESC1_HEADER_INDEX_SMASK)
                                        >> SDMA_DESC1_HEADER_INDEX_SHIFT),
                                (u8)((desc[1] & SDMA_DESC1_HEADER_MODE_SMASK)
                                        >> SDMA_DESC1_HEADER_MODE_SHIFT));
                head = (head + 1) & sde->sdma_mask;
        }
}

/*
 * add the generation number into
 * the qw1 and return
 */
static inline u64 add_gen(struct sdma_engine *sde, u64 qw1)
{
        u8 generation = (sde->descq_tail >> sde->sdma_shift) & 3;

        qw1 &= ~SDMA_DESC1_GENERATION_SMASK;
        qw1 |= ((u64)generation & SDMA_DESC1_GENERATION_MASK)
                        << SDMA_DESC1_GENERATION_SHIFT;
        return qw1;
}

/*
 * This routine submits the indicated tx
 *
 * Space has already been guaranteed and
 * tail side of ring is locked.
 *
 * The hardware tail update is done
 * in the caller and that is facilitated
 * by returning the new tail.
 *
 * There is special case logic for ahg
 * to not add the generation number for
 * up to 2 descriptors that follow the
 * first descriptor.
 *
 */
static inline u16 submit_tx(struct sdma_engine *sde, struct sdma_txreq *tx)
{
        int i;
        u16 tail;
        struct sdma_desc *descp = tx->descp;
        u8 skip = 0, mode = ahg_mode(tx);

        tail = sde->descq_tail & sde->sdma_mask;
        sde->descq[tail].qw[0] = cpu_to_le64(descp->qw[0]);
        sde->descq[tail].qw[1] = cpu_to_le64(add_gen(sde, descp->qw[1]));
        trace_hfi1_sdma_descriptor(sde, descp->qw[0], descp->qw[1],
                                   tail, &sde->descq[tail]);
        tail = ++sde->descq_tail & sde->sdma_mask;
        descp++;
        if (mode > SDMA_AHG_APPLY_UPDATE1)
                skip = mode >> 1;
        for (i = 1; i < tx->num_desc; i++, descp++) {
                u64 qw1;

                sde->descq[tail].qw[0] = cpu_to_le64(descp->qw[0]);
                if (skip) {
                        /* edits don't have generation */
                        qw1 = descp->qw[1];
                        skip--;
                } else {
                        /* replace generation with real one for non-edits */
                        qw1 = add_gen(sde, descp->qw[1]);
                }
                sde->descq[tail].qw[1] = cpu_to_le64(qw1);
                trace_hfi1_sdma_descriptor(sde, descp->qw[0], qw1,
                                           tail, &sde->descq[tail]);
                tail = ++sde->descq_tail & sde->sdma_mask;
        }
        tx->next_descq_idx = tail;
#ifdef CONFIG_HFI1_DEBUG_SDMA_ORDER
        tx->sn = sde->tail_sn++;
        trace_hfi1_sdma_in_sn(sde, tx->sn);
        WARN_ON_ONCE(sde->tx_ring[sde->tx_tail & sde->sdma_mask]);
#endif
        sde->tx_ring[sde->tx_tail++ & sde->sdma_mask] = tx;
        sde->desc_avail -= tx->num_desc;
        return tail;
}

/*
 * Check for progress
 */
static int sdma_check_progress(
        struct sdma_engine *sde,
        struct iowait *wait,
        struct sdma_txreq *tx)
{
        int ret;

        sde->desc_avail = sdma_descq_freecnt(sde);
        if (tx->num_desc <= sde->desc_avail)
                return -EAGAIN;
        /* pulse the head_lock */
        if (wait && wait->sleep) {
                unsigned seq;

                seq = raw_seqcount_begin(
                        (const seqcount_t *)&sde->head_lock.seqcount);
                ret = wait->sleep(sde, wait, tx, seq);
                if (ret == -EAGAIN)
                        sde->desc_avail = sdma_descq_freecnt(sde);
        } else
                ret = -EBUSY;
        return ret;
}

/**
 * sdma_send_txreq() - submit a tx req to ring
 * @sde: sdma engine to use
 * @wait: wait structure to use when full (may be NULL)
 * @tx: sdma_txreq to submit
 *
 * The call submits the tx into the ring.  If a iowait structure is non-NULL
 * the packet will be queued to the list in wait.
 *
 * Return:
 * 0 - Success, -EINVAL - sdma_txreq incomplete, -EBUSY - no space in
 * ring (wait == NULL)
 * -EIOCBQUEUED - tx queued to iowait, -ECOMM bad sdma state
 */
int sdma_send_txreq(struct sdma_engine *sde,
                    struct iowait *wait,
                    struct sdma_txreq *tx)
{
        int ret = 0;
        u16 tail;
        unsigned long flags;

        /* user should have supplied entire packet */
        if (unlikely(tx->tlen))
                return -EINVAL;
        tx->wait = wait;
        spin_lock_irqsave(&sde->tail_lock, flags);
retry:
        if (unlikely(!__sdma_running(sde)))
                goto unlock_noconn;
        if (unlikely(tx->num_desc > sde->desc_avail))
                goto nodesc;
        tail = submit_tx(sde, tx);
        if (wait)
                atomic_inc(&wait->sdma_busy);
        sdma_update_tail(sde, tail);
unlock:
        spin_unlock_irqrestore(&sde->tail_lock, flags);
        return ret;
unlock_noconn:
        if (wait)
                atomic_inc(&wait->sdma_busy);
        tx->next_descq_idx = 0;
#ifdef CONFIG_HFI1_DEBUG_SDMA_ORDER
        tx->sn = sde->tail_sn++;
        trace_hfi1_sdma_in_sn(sde, tx->sn);
#endif
        spin_lock(&sde->flushlist_lock);
        list_add_tail(&tx->list, &sde->flushlist);
        spin_unlock(&sde->flushlist_lock);
        if (wait) {
                wait->tx_count++;
                wait->count += tx->num_desc;
        }
        schedule_work(&sde->flush_worker);
        ret = -ECOMM;
        goto unlock;
nodesc:
        ret = sdma_check_progress(sde, wait, tx);
        if (ret == -EAGAIN) {
                ret = 0;
                goto retry;
        }
        sde->descq_full_count++;
        goto unlock;
}

/**
 * sdma_send_txlist() - submit a list of tx req to ring
 * @sde: sdma engine to use
 * @wait: wait structure to use when full (may be NULL)
 * @tx_list: list of sdma_txreqs to submit
 *
 * The call submits the list into the ring.
 *
 * If the iowait structure is non-NULL and not equal to the iowait list
 * the unprocessed part of the list  will be appended to the list in wait.
 *
 * In all cases, the tx_list will be updated so the head of the tx_list is
 * the list of descriptors that have yet to be transmitted.
 *
 * The intent of this call is to provide a more efficient
 * way of submitting multiple packets to SDMA while holding the tail
 * side locking.
 *
 * Return:
 * 0 - Success, -EINVAL - sdma_txreq incomplete, -EBUSY - no space in ring
 * (wait == NULL)
 * -EIOCBQUEUED - tx queued to iowait, -ECOMM bad sdma state
 */
int sdma_send_txlist(struct sdma_engine *sde,
                    struct iowait *wait,
                    struct list_head *tx_list)
{
        struct sdma_txreq *tx, *tx_next;
        int ret = 0;
        unsigned long flags;
        u16 tail = INVALID_TAIL;
        int count = 0;

        spin_lock_irqsave(&sde->tail_lock, flags);
retry:
        list_for_each_entry_safe(tx, tx_next, tx_list, list) {
                tx->wait = wait;
                if (unlikely(!__sdma_running(sde)))
                        goto unlock_noconn;
                if (unlikely(tx->num_desc > sde->desc_avail))
                        goto nodesc;
                if (unlikely(tx->tlen)) {
                        ret = -EINVAL;
                        goto update_tail;
                }
                list_del_init(&tx->list);
                tail = submit_tx(sde, tx);
                count++;
                if (tail != INVALID_TAIL &&
                    (count & SDMA_TAIL_UPDATE_THRESH) == 0) {
                        sdma_update_tail(sde, tail);
                        tail = INVALID_TAIL;
                }
        }
update_tail:
        if (wait)
                atomic_add(count, &wait->sdma_busy);
        if (tail != INVALID_TAIL)
                sdma_update_tail(sde, tail);
        spin_unlock_irqrestore(&sde->tail_lock, flags);
        return ret;
unlock_noconn:
        spin_lock(&sde->flushlist_lock);
        list_for_each_entry_safe(tx, tx_next, tx_list, list) {
                tx->wait = wait;
                list_del_init(&tx->list);
                if (wait)
                        atomic_inc(&wait->sdma_busy);
                tx->next_descq_idx = 0;
#ifdef CONFIG_HFI1_DEBUG_SDMA_ORDER
                tx->sn = sde->tail_sn++;
                trace_hfi1_sdma_in_sn(sde, tx->sn);
#endif
                list_add_tail(&tx->list, &sde->flushlist);
                if (wait) {
                        wait->tx_count++;
                        wait->count += tx->num_desc;
                }
        }
        spin_unlock(&sde->flushlist_lock);
        schedule_work(&sde->flush_worker);
        ret = -ECOMM;
        goto update_tail;
nodesc:
        ret = sdma_check_progress(sde, wait, tx);
        if (ret == -EAGAIN) {
                ret = 0;
                goto retry;
        }
        sde->descq_full_count++;
        goto update_tail;
}

static void sdma_process_event(struct sdma_engine *sde,
        enum sdma_events event)
{
        unsigned long flags;

        spin_lock_irqsave(&sde->tail_lock, flags);
        write_seqlock(&sde->head_lock);

        __sdma_process_event(sde, event);

        if (sde->state.current_state == sdma_state_s99_running)
                sdma_desc_avail(sde, sdma_descq_freecnt(sde));

        write_sequnlock(&sde->head_lock);
        spin_unlock_irqrestore(&sde->tail_lock, flags);
}

static void __sdma_process_event(struct sdma_engine *sde,
        enum sdma_events event)
{
        struct sdma_state *ss = &sde->state;
        int need_progress = 0;

        /* CONFIG SDMA temporary */
#ifdef CONFIG_SDMA_VERBOSITY
        dd_dev_err(sde->dd, "CONFIG SDMA(%u) [%s] %s\n", sde->this_idx,
                   sdma_state_names[ss->current_state],
                   sdma_event_names[event]);
#endif

        switch (ss->current_state) {
        case sdma_state_s00_hw_down:
                switch (event) {
                case sdma_event_e00_go_hw_down:
                        break;
                case 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 sdma_event_e10_go_hw_start:
                        /* This reference means the state machine is started */
                        sdma_get(&sde->state);
                        sdma_set_state(sde,
                                sdma_state_s10_hw_start_up_halt_wait);
                        break;
                case sdma_event_e15_hw_halt_done:
                        break;
                case sdma_event_e25_hw_clean_up_done:
                        break;
                case sdma_event_e40_sw_cleaned:
                        sdma_sw_tear_down(sde);
                        break;
                case sdma_event_e50_hw_cleaned:
                        break;
                case sdma_event_e60_hw_halted:
                        break;
                case sdma_event_e70_go_idle:
                        break;
                case sdma_event_e80_hw_freeze:
                        break;
                case sdma_event_e81_hw_frozen:
                        break;
                case sdma_event_e82_hw_unfreeze:
                        break;
                case sdma_event_e85_link_down:
                        break;
                case sdma_event_e90_sw_halted:
                        break;
                }
                break;

        case sdma_state_s10_hw_start_up_halt_wait:
                switch (event) {
                case sdma_event_e00_go_hw_down:
                        sdma_set_state(sde, sdma_state_s00_hw_down);
                        sdma_sw_tear_down(sde);
                        break;
                case sdma_event_e10_go_hw_start:
                        break;
                case sdma_event_e15_hw_halt_done:
                        sdma_set_state(sde,
                                sdma_state_s15_hw_start_up_clean_wait);
                        sdma_start_hw_clean_up(sde);
                        break;
                case sdma_event_e25_hw_clean_up_done:
                        break;
                case sdma_event_e30_go_running:
                        ss->go_s99_running = 1;
                        break;
                case sdma_event_e40_sw_cleaned:
                        break;
                case sdma_event_e50_hw_cleaned:
                        break;
                case sdma_event_e60_hw_halted:
                        sdma_start_err_halt_wait(sde);
                        break;
                case sdma_event_e70_go_idle:
                        ss->go_s99_running = 0;
                        break;
                case sdma_event_e80_hw_freeze:
                        break;
                case sdma_event_e81_hw_frozen:
                        break;
                case sdma_event_e82_hw_unfreeze:
                        break;
                case sdma_event_e85_link_down:
                        break;
                case sdma_event_e90_sw_halted:
                        break;
                }
                break;

        case sdma_state_s15_hw_start_up_clean_wait:
                switch (event) {
                case sdma_event_e00_go_hw_down:
                        sdma_set_state(sde, sdma_state_s00_hw_down);
                        sdma_sw_tear_down(sde);
                        break;
                case sdma_event_e10_go_hw_start:
                        break;
                case sdma_event_e15_hw_halt_done:
                        break;
                case sdma_event_e25_hw_clean_up_done:
                        sdma_hw_start_up(sde);
                        sdma_set_state(sde, ss->go_s99_running ?
                                       sdma_state_s99_running :
                                       sdma_state_s20_idle);
                        break;
                case sdma_event_e30_go_running:
                        ss->go_s99_running = 1;
                        break;
                case sdma_event_e40_sw_cleaned:
                        break;
                case sdma_event_e50_hw_cleaned:
                        break;
                case sdma_event_e60_hw_halted:
                        break;
                case sdma_event_e70_go_idle:
                        ss->go_s99_running = 0;
                        break;
                case sdma_event_e80_hw_freeze:
                        break;
                case sdma_event_e81_hw_frozen:
                        break;
                case sdma_event_e82_hw_unfreeze:
                        break;
                case sdma_event_e85_link_down:
                        break;
                case sdma_event_e90_sw_halted:
                        break;
                }
                break;

        case sdma_state_s20_idle:
                switch (event) {
                case sdma_event_e00_go_hw_down:
                        sdma_set_state(sde, sdma_state_s00_hw_down);
                        sdma_sw_tear_down(sde);
                        break;
                case sdma_event_e10_go_hw_start:
                        break;
                case sdma_event_e15_hw_halt_done:
                        break;
                case sdma_event_e25_hw_clean_up_done:
                        break;
                case sdma_event_e30_go_running:
                        sdma_set_state(sde, sdma_state_s99_running);
                        ss->go_s99_running = 1;
                        break;
                case sdma_event_e40_sw_cleaned:
                        break;
                case sdma_event_e50_hw_cleaned:
                        break;
                case sdma_event_e60_hw_halted:
                        sdma_set_state(sde, sdma_state_s50_hw_halt_wait);
                        sdma_start_err_halt_wait(sde);
                        break;
                case sdma_event_e70_go_idle:
                        break;
                case sdma_event_e85_link_down:
                        /* fall through */
                case sdma_event_e80_hw_freeze:
                        sdma_set_state(sde, sdma_state_s80_hw_freeze);
                        atomic_dec(&sde->dd->sdma_unfreeze_count);
                        wake_up_interruptible(&sde->dd->sdma_unfreeze_wq);
                        break;
                case sdma_event_e81_hw_frozen:
                        break;
                case sdma_event_e82_hw_unfreeze:
                        break;
                case sdma_event_e90_sw_halted:
                        break;
                }
                break;

        case sdma_state_s30_sw_clean_up_wait:
                switch (event) {
                case sdma_event_e00_go_hw_down:
                        sdma_set_state(sde, sdma_state_s00_hw_down);
                        break;
                case sdma_event_e10_go_hw_start:
                        break;
                case sdma_event_e15_hw_halt_done:
                        break;
                case sdma_event_e25_hw_clean_up_done:
                        break;
                case sdma_event_e30_go_running:
                        ss->go_s99_running = 1;
                        break;
                case sdma_event_e40_sw_cleaned:
                        sdma_set_state(sde, sdma_state_s40_hw_clean_up_wait);
                        sdma_start_hw_clean_up(sde);
                        break;
                case sdma_event_e50_hw_cleaned:
                        break;
                case sdma_event_e60_hw_halted:
                        break;
                case sdma_event_e70_go_idle:
                        ss->go_s99_running = 0;
                        break;
                case sdma_event_e80_hw_freeze:
                        break;
                case sdma_event_e81_hw_frozen:
                        break;
                case sdma_event_e82_hw_unfreeze:
                        break;
                case sdma_event_e85_link_down:
                        ss->go_s99_running = 0;
                        break;
                case sdma_event_e90_sw_halted:
                        break;
                }
                break;

        case sdma_state_s40_hw_clean_up_wait:
                switch (event) {
                case sdma_event_e00_go_hw_down:
                        sdma_set_state(sde, sdma_state_s00_hw_down);
                        sdma_start_sw_clean_up(sde);
                        break;
                case sdma_event_e10_go_hw_start:
                        break;
                case sdma_event_e15_hw_halt_done:
                        break;
                case sdma_event_e25_hw_clean_up_done:
                        sdma_hw_start_up(sde);
                        sdma_set_state(sde, ss->go_s99_running ?
                                       sdma_state_s99_running :
                                       sdma_state_s20_idle);
                        break;
                case sdma_event_e30_go_running:
                        ss->go_s99_running = 1;
                        break;
                case sdma_event_e40_sw_cleaned:
                        break;
                case sdma_event_e50_hw_cleaned:
                        break;
                case sdma_event_e60_hw_halted:
                        break;
                case sdma_event_e70_go_idle:
                        ss->go_s99_running = 0;
                        break;
                case sdma_event_e80_hw_freeze:
                        break;
                case sdma_event_e81_hw_frozen:
                        break;
                case sdma_event_e82_hw_unfreeze:
                        break;
                case sdma_event_e85_link_down:
                        ss->go_s99_running = 0;
                        break;
                case sdma_event_e90_sw_halted:
                        break;
                }
                break;

        case sdma_state_s50_hw_halt_wait:
                switch (event) {
                case sdma_event_e00_go_hw_down:
                        sdma_set_state(sde, sdma_state_s00_hw_down);
                        sdma_start_sw_clean_up(sde);
                        break;
                case sdma_event_e10_go_hw_start:
                        break;
                case sdma_event_e15_hw_halt_done:
                        sdma_set_state(sde, sdma_state_s30_sw_clean_up_wait);
                        sdma_start_sw_clean_up(sde);
                        break;
                case sdma_event_e25_hw_clean_up_done:
                        break;
                case sdma_event_e30_go_running:
                        ss->go_s99_running = 1;
                        break;
                case sdma_event_e40_sw_cleaned:
                        break;
                case sdma_event_e50_hw_cleaned:
                        break;
                case sdma_event_e60_hw_halted:
                        sdma_start_err_halt_wait(sde);
                        break;
                case sdma_event_e70_go_idle:
                        ss->go_s99_running = 0;
                        break;
                case sdma_event_e80_hw_freeze:
                        break;
                case sdma_event_e81_hw_frozen:
                        break;
                case sdma_event_e82_hw_unfreeze:
                        break;
                case sdma_event_e85_link_down:
                        ss->go_s99_running = 0;
                        break;
                case sdma_event_e90_sw_halted:
                        break;
                }
                break;

        case sdma_state_s60_idle_halt_wait:
                switch (event) {
                case sdma_event_e00_go_hw_down:
                        sdma_set_state(sde, sdma_state_s00_hw_down);
                        sdma_start_sw_clean_up(sde);
                        break;
                case sdma_event_e10_go_hw_start:
                        break;
                case sdma_event_e15_hw_halt_done:
                        sdma_set_state(sde, sdma_state_s30_sw_clean_up_wait);
                        sdma_start_sw_clean_up(sde);
                        break;
                case sdma_event_e25_hw_clean_up_done:
                        break;
                case sdma_event_e30_go_running:
                        ss->go_s99_running = 1;
                        break;
                case sdma_event_e40_sw_cleaned:
                        break;
                case sdma_event_e50_hw_cleaned:
                        break;
                case sdma_event_e60_hw_halted:
                        sdma_start_err_halt_wait(sde);
                        break;
                case sdma_event_e70_go_idle:
                        ss->go_s99_running = 0;
                        break;
                case sdma_event_e80_hw_freeze:
                        break;
                case sdma_event_e81_hw_frozen:
                        break;
                case sdma_event_e82_hw_unfreeze:
                        break;
                case sdma_event_e85_link_down:
                        break;
                case sdma_event_e90_sw_halted:
                        break;
                }
                break;

        case sdma_state_s80_hw_freeze:
                switch (event) {
                case sdma_event_e00_go_hw_down:
                        sdma_set_state(sde, sdma_state_s00_hw_down);
                        sdma_start_sw_clean_up(sde);
                        break;
                case sdma_event_e10_go_hw_start:
                        break;
                case sdma_event_e15_hw_halt_done:
                        break;
                case sdma_event_e25_hw_clean_up_done:
                        break;
                case sdma_event_e30_go_running:
                        ss->go_s99_running = 1;
                        break;
                case sdma_event_e40_sw_cleaned:
                        break;
                case sdma_event_e50_hw_cleaned:
                        break;
                case sdma_event_e60_hw_halted:
                        break;
                case sdma_event_e70_go_idle:
                        ss->go_s99_running = 0;
                        break;
                case sdma_event_e80_hw_freeze:
                        break;
                case sdma_event_e81_hw_frozen:
                        sdma_set_state(sde, sdma_state_s82_freeze_sw_clean);
                        sdma_start_sw_clean_up(sde);
                        break;
                case sdma_event_e82_hw_unfreeze:
                        break;
                case sdma_event_e85_link_down:
                        break;
                case sdma_event_e90_sw_halted:
                        break;
                }
                break;

        case sdma_state_s82_freeze_sw_clean:
                switch (event) {
                case sdma_event_e00_go_hw_down:
                        sdma_set_state(sde, sdma_state_s00_hw_down);
                        sdma_start_sw_clean_up(sde);
                        break;
                case sdma_event_e10_go_hw_start:
                        break;
                case sdma_event_e15_hw_halt_done:
                        break;
                case sdma_event_e25_hw_clean_up_done:
                        break;
                case sdma_event_e30_go_running:
                        ss->go_s99_running = 1;
                        break;
                case sdma_event_e40_sw_cleaned:
                        /* notify caller this engine is done cleaning */
                        atomic_dec(&sde->dd->sdma_unfreeze_count);
                        wake_up_interruptible(&sde->dd->sdma_unfreeze_wq);
                        break;
                case sdma_event_e50_hw_cleaned:
                        break;
                case sdma_event_e60_hw_halted:
                        break;
                case sdma_event_e70_go_idle:
                        ss->go_s99_running = 0;
                        break;
                case sdma_event_e80_hw_freeze:
                        break;
                case sdma_event_e81_hw_frozen:
                        break;
                case sdma_event_e82_hw_unfreeze:
                        sdma_hw_start_up(sde);
                        sdma_set_state(sde, ss->go_s99_running ?
                                       sdma_state_s99_running :
                                       sdma_state_s20_idle);
                        break;
                case sdma_event_e85_link_down:
                        break;
                case sdma_event_e90_sw_halted:
                        break;
                }
                break;

        case sdma_state_s99_running:
                switch (event) {
                case sdma_event_e00_go_hw_down:
                        sdma_set_state(sde, sdma_state_s00_hw_down);
                        sdma_start_sw_clean_up(sde);
                        break;
                case sdma_event_e10_go_hw_start:
                        break;
                case sdma_event_e15_hw_halt_done:
                        break;
                case sdma_event_e25_hw_clean_up_done:
                        break;
                case sdma_event_e30_go_running:
                        break;
                case sdma_event_e40_sw_cleaned:
                        break;
                case sdma_event_e50_hw_cleaned:
                        break;
                case sdma_event_e60_hw_halted:
                        need_progress = 1;
                        sdma_err_progress_check_schedule(sde);
                case sdma_event_e90_sw_halted:
                        /*
                        * SW initiated halt does not perform engines
                        * progress check
                        */
                        sdma_set_state(sde, sdma_state_s50_hw_halt_wait);
                        sdma_start_err_halt_wait(sde);
                        break;
                case sdma_event_e70_go_idle:
                        sdma_set_state(sde, sdma_state_s60_idle_halt_wait);
                        break;
                case sdma_event_e85_link_down:
                        ss->go_s99_running = 0;
                        /* fall through */
                case sdma_event_e80_hw_freeze:
                        sdma_set_state(sde, sdma_state_s80_hw_freeze);
                        atomic_dec(&sde->dd->sdma_unfreeze_count);
                        wake_up_interruptible(&sde->dd->sdma_unfreeze_wq);
                        break;
                case sdma_event_e81_hw_frozen:
                        break;
                case sdma_event_e82_hw_unfreeze:
                        break;
                }
                break;
        }

        ss->last_event = event;
        if (need_progress)
                sdma_make_progress(sde, 0);
}

/*
 * _extend_sdma_tx_descs() - helper to extend txreq
 *
 * This is called once the initial nominal allocation
 * of descriptors in the sdma_txreq is exhausted.
 *
 * The code will bump the allocation up to the max
 * of MAX_DESC (64) descriptors.  There doesn't seem
 * much point in an interim step.
 *
 */
int _extend_sdma_tx_descs(struct hfi1_devdata *dd, struct sdma_txreq *tx)
{
        int i;

        tx->descp = kmalloc_array(
                        MAX_DESC,
                        sizeof(struct sdma_desc),
                        GFP_ATOMIC);
        if (!tx->descp)
                return -ENOMEM;
        tx->desc_limit = MAX_DESC;
        /* copy ones already built */
        for (i = 0; i < tx->num_desc; i++)
                tx->descp[i] = tx->descs[i];
        return 0;
}

/* Update sdes when the lmc changes */
void sdma_update_lmc(struct hfi1_devdata *dd, u64 mask, u32 lid)
{
        struct sdma_engine *sde;
        int i;
        u64 sreg;

        sreg = ((mask & SD(CHECK_SLID_MASK_MASK)) <<
                SD(CHECK_SLID_MASK_SHIFT)) |
                (((lid & mask) & SD(CHECK_SLID_VALUE_MASK)) <<
                SD(CHECK_SLID_VALUE_SHIFT));

        for (i = 0; i < dd->num_sdma; i++) {
                hfi1_cdbg(LINKVERB, "SendDmaEngine[%d].SLID_CHECK = 0x%x",
                          i, (u32)sreg);
                sde = &dd->per_sdma[i];
                write_sde_csr(sde, SD(CHECK_SLID), sreg);
        }
}

/* tx not dword sized - pad */
int _pad_sdma_tx_descs(struct hfi1_devdata *dd, struct sdma_txreq *tx)
{
        int rval = 0;

        if ((unlikely(tx->num_desc == tx->desc_limit))) {
                rval = _extend_sdma_tx_descs(dd, tx);
                if (rval)
                        return rval;
        }
        /* finish the one just added  */
        tx->num_desc++;
        make_tx_sdma_desc(
                tx,
                SDMA_MAP_NONE,
                dd->sdma_pad_phys,
                sizeof(u32) - (tx->packet_len & (sizeof(u32) - 1)));
        _sdma_close_tx(dd, tx);
        return rval;
}

/*
 * Add ahg to the sdma_txreq
 *
 * The logic will consume up to 3
 * descriptors at the beginning of
 * sdma_txreq.
 */
void _sdma_txreq_ahgadd(
        struct sdma_txreq *tx,
        u8 num_ahg,
        u8 ahg_entry,
        u32 *ahg,
        u8 ahg_hlen)
{
        u32 i, shift = 0, desc = 0;
        u8 mode;

        WARN_ON_ONCE(num_ahg > 9 || (ahg_hlen & 3) || ahg_hlen == 4);
        /* compute mode */
        if (num_ahg == 1)
                mode = SDMA_AHG_APPLY_UPDATE1;
        else if (num_ahg <= 5)
                mode = SDMA_AHG_APPLY_UPDATE2;
        else
                mode = SDMA_AHG_APPLY_UPDATE3;
        tx->num_desc++;
        /* initialize to consumed descriptors to zero */
        switch (mode) {
        case SDMA_AHG_APPLY_UPDATE3:
                tx->num_desc++;
                tx->descs[2].qw[0] = 0;
                tx->descs[2].qw[1] = 0;
                /* FALLTHROUGH */
        case SDMA_AHG_APPLY_UPDATE2:
                tx->num_desc++;
                tx->descs[1].qw[0] = 0;
                tx->descs[1].qw[1] = 0;
                break;
        }
        ahg_hlen >>= 2;
        tx->descs[0].qw[1] |=
                (((u64)ahg_entry & SDMA_DESC1_HEADER_INDEX_MASK)
                        << SDMA_DESC1_HEADER_INDEX_SHIFT) |
                (((u64)ahg_hlen & SDMA_DESC1_HEADER_DWS_MASK)
                        << SDMA_DESC1_HEADER_DWS_SHIFT) |
                (((u64)mode & SDMA_DESC1_HEADER_MODE_MASK)
                        << SDMA_DESC1_HEADER_MODE_SHIFT) |
                (((u64)ahg[0] & SDMA_DESC1_HEADER_UPDATE1_MASK)
                        << SDMA_DESC1_HEADER_UPDATE1_SHIFT);
        for (i = 0; i < (num_ahg - 1); i++) {
                if (!shift && !(i & 2))
                        desc++;
                tx->descs[desc].qw[!!(i & 2)] |=
                        (((u64)ahg[i + 1])
                                << shift);
                shift = (shift + 32) & 63;
        }
}

/**
 * sdma_ahg_alloc - allocate an AHG entry
 * @sde: engine to allocate from
 *
 * Return:
 * 0-31 when successful, -EOPNOTSUPP if AHG is not enabled,
 * -ENOSPC if an entry is not available
 */
int sdma_ahg_alloc(struct sdma_engine *sde)
{
        int nr;
        int oldbit;

        if (!sde) {
                trace_hfi1_ahg_allocate(sde, -EINVAL);
                return -EINVAL;
        }
        while (1) {
                nr = ffz(ACCESS_ONCE(sde->ahg_bits));
                if (nr > 31) {
                        trace_hfi1_ahg_allocate(sde, -ENOSPC);
                        return -ENOSPC;
                }
                oldbit = test_and_set_bit(nr, &sde->ahg_bits);
                if (!oldbit)
                        break;
                cpu_relax();
        }
        trace_hfi1_ahg_allocate(sde, nr);
        return nr;
}

/**
 * sdma_ahg_free - free an AHG entry
 * @sde: engine to return AHG entry
 * @ahg_index: index to free
 *
 * This routine frees the indicate AHG entry.
 */
void sdma_ahg_free(struct sdma_engine *sde, int ahg_index)
{
        if (!sde)
                return;
        trace_hfi1_ahg_deallocate(sde, ahg_index);
        if (ahg_index < 0 || ahg_index > 31)
                return;
        clear_bit(ahg_index, &sde->ahg_bits);
}

/*
 * SPC freeze handling for SDMA engines.  Called when the driver knows
 * the SPC is going into a freeze but before the freeze is fully
 * settled.  Generally an error interrupt.
 *
 * This event will pull the engine out of running so no more entries can be
 * added to the engine's queue.
 */
void sdma_freeze_notify(struct hfi1_devdata *dd, int link_down)
{
        int i;
        enum sdma_events event = link_down ? sdma_event_e85_link_down :
                                             sdma_event_e80_hw_freeze;

        /* set up the wait but do not wait here */
        atomic_set(&dd->sdma_unfreeze_count, dd->num_sdma);

        /* tell all engines to stop running and wait */
        for (i = 0; i < dd->num_sdma; i++)
                sdma_process_event(&dd->per_sdma[i], event);

        /* sdma_freeze() will wait for all engines to have stopped */
}

/*
 * SPC freeze handling for SDMA engines.  Called when the driver knows
 * the SPC is fully frozen.
 */
void sdma_freeze(struct hfi1_devdata *dd)
{
        int i;
        int ret;

        /*
         * Make sure all engines have moved out of the running state before
         * continuing.
         */
        ret = wait_event_interruptible(dd->sdma_unfreeze_wq,
                                atomic_read(&dd->sdma_unfreeze_count) <= 0);
        /* interrupted or count is negative, then unloading - just exit */
        if (ret || atomic_read(&dd->sdma_unfreeze_count) < 0)
                return;

        /* set up the count for the next wait */
        atomic_set(&dd->sdma_unfreeze_count, dd->num_sdma);

        /* tell all engines that the SPC is frozen, they can start cleaning */
        for (i = 0; i < dd->num_sdma; i++)
                sdma_process_event(&dd->per_sdma[i], sdma_event_e81_hw_frozen);

        /*
         * Wait for everyone to finish software clean before exiting.  The
         * software clean will read engine CSRs, so must be completed before
         * the next step, which will clear the engine CSRs.
         */
        (void) wait_event_interruptible(dd->sdma_unfreeze_wq,
                                atomic_read(&dd->sdma_unfreeze_count) <= 0);
        /* no need to check results - done no matter what */
}

/*
 * SPC freeze handling for the SDMA engines.  Called after the SPC is unfrozen.
 *
 * The SPC freeze acts like a SDMA halt and a hardware clean combined.  All
 * that is left is a software clean.  We could do it after the SPC is fully
 * frozen, but then we'd have to add another state to wait for the unfreeze.
 * Instead, just defer the software clean until the unfreeze step.
 */
void sdma_unfreeze(struct hfi1_devdata *dd)
{
        int i;

        /* tell all engines start freeze clean up */
        for (i = 0; i < dd->num_sdma; i++)
                sdma_process_event(&dd->per_sdma[i],
                                        sdma_event_e82_hw_unfreeze);
}

/**
 * _sdma_engine_progress_schedule() - schedule progress on engine
 * @sde: sdma_engine to schedule progress
 *
 */
void _sdma_engine_progress_schedule(
        struct sdma_engine *sde)
{
        trace_hfi1_sdma_engine_progress(sde, sde->progress_mask);
        /* assume we have selected a good cpu */
        write_csr(sde->dd,
                  CCE_INT_FORCE + (8*(IS_SDMA_START/64)), sde->progress_mask);
}