Merge tag 'armsoc-dt' of git://git.kernel.org/pub/scm/linux/kernel/git/arm/arm-soc

[deliverable/linux.git] / drivers / dma / ioat / dma.c

/*
 * Intel I/OAT DMA Linux driver
 * Copyright(c) 2004 - 2015 Intel Corporation.
 *
 * This program is free software; you can redistribute it and/or modify it
 * under the terms and conditions of the GNU General Public License,
 * version 2, 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.
 *
 * The full GNU General Public License is included in this distribution in
 * the file called "COPYING".
 *
 */

/*
 * This driver supports an Intel I/OAT DMA engine, which does asynchronous
 * copy operations.
 */

#include <linux/init.h>
#include <linux/module.h>
#include <linux/slab.h>
#include <linux/pci.h>
#include <linux/interrupt.h>
#include <linux/dmaengine.h>
#include <linux/delay.h>
#include <linux/dma-mapping.h>
#include <linux/workqueue.h>
#include <linux/prefetch.h>
#include <linux/sizes.h>
#include "dma.h"
#include "registers.h"
#include "hw.h"

#include "../dmaengine.h"

static void ioat_eh(struct ioatdma_chan *ioat_chan);

/**
 * ioat_dma_do_interrupt - handler used for single vector interrupt mode
 * @irq: interrupt id
 * @data: interrupt data
 */
irqreturn_t ioat_dma_do_interrupt(int irq, void *data)
{
        struct ioatdma_device *instance = data;
        struct ioatdma_chan *ioat_chan;
        unsigned long attnstatus;
        int bit;
        u8 intrctrl;

        intrctrl = readb(instance->reg_base + IOAT_INTRCTRL_OFFSET);

        if (!(intrctrl & IOAT_INTRCTRL_MASTER_INT_EN))
                return IRQ_NONE;

        if (!(intrctrl & IOAT_INTRCTRL_INT_STATUS)) {
                writeb(intrctrl, instance->reg_base + IOAT_INTRCTRL_OFFSET);
                return IRQ_NONE;
        }

        attnstatus = readl(instance->reg_base + IOAT_ATTNSTATUS_OFFSET);
        for_each_set_bit(bit, &attnstatus, BITS_PER_LONG) {
                ioat_chan = ioat_chan_by_index(instance, bit);
                if (test_bit(IOAT_RUN, &ioat_chan->state))
                        tasklet_schedule(&ioat_chan->cleanup_task);
        }

        writeb(intrctrl, instance->reg_base + IOAT_INTRCTRL_OFFSET);
        return IRQ_HANDLED;
}

/**
 * ioat_dma_do_interrupt_msix - handler used for vector-per-channel interrupt mode
 * @irq: interrupt id
 * @data: interrupt data
 */
irqreturn_t ioat_dma_do_interrupt_msix(int irq, void *data)
{
        struct ioatdma_chan *ioat_chan = data;

        if (test_bit(IOAT_RUN, &ioat_chan->state))
                tasklet_schedule(&ioat_chan->cleanup_task);

        return IRQ_HANDLED;
}

void ioat_stop(struct ioatdma_chan *ioat_chan)
{
        struct ioatdma_device *ioat_dma = ioat_chan->ioat_dma;
        struct pci_dev *pdev = ioat_dma->pdev;
        int chan_id = chan_num(ioat_chan);
        struct msix_entry *msix;

        /* 1/ stop irq from firing tasklets
         * 2/ stop the tasklet from re-arming irqs
         */
        clear_bit(IOAT_RUN, &ioat_chan->state);

        /* flush inflight interrupts */
        switch (ioat_dma->irq_mode) {
        case IOAT_MSIX:
                msix = &ioat_dma->msix_entries[chan_id];
                synchronize_irq(msix->vector);
                break;
        case IOAT_MSI:
        case IOAT_INTX:
                synchronize_irq(pdev->irq);
                break;
        default:
                break;
        }

        /* flush inflight timers */
        del_timer_sync(&ioat_chan->timer);

        /* flush inflight tasklet runs */
        tasklet_kill(&ioat_chan->cleanup_task);

        /* final cleanup now that everything is quiesced and can't re-arm */
        ioat_cleanup_event((unsigned long)&ioat_chan->dma_chan);
}

static void __ioat_issue_pending(struct ioatdma_chan *ioat_chan)
{
        ioat_chan->dmacount += ioat_ring_pending(ioat_chan);
        ioat_chan->issued = ioat_chan->head;
        writew(ioat_chan->dmacount,
               ioat_chan->reg_base + IOAT_CHAN_DMACOUNT_OFFSET);
        dev_dbg(to_dev(ioat_chan),
                "%s: head: %#x tail: %#x issued: %#x count: %#x\n",
                __func__, ioat_chan->head, ioat_chan->tail,
                ioat_chan->issued, ioat_chan->dmacount);
}

void ioat_issue_pending(struct dma_chan *c)
{
        struct ioatdma_chan *ioat_chan = to_ioat_chan(c);

        if (ioat_ring_pending(ioat_chan)) {
                spin_lock_bh(&ioat_chan->prep_lock);
                __ioat_issue_pending(ioat_chan);
                spin_unlock_bh(&ioat_chan->prep_lock);
        }
}

/**
 * ioat_update_pending - log pending descriptors
 * @ioat: ioat+ channel
 *
 * Check if the number of unsubmitted descriptors has exceeded the
 * watermark.  Called with prep_lock held
 */
static void ioat_update_pending(struct ioatdma_chan *ioat_chan)
{
        if (ioat_ring_pending(ioat_chan) > ioat_pending_level)
                __ioat_issue_pending(ioat_chan);
}

static void __ioat_start_null_desc(struct ioatdma_chan *ioat_chan)
{
        struct ioat_ring_ent *desc;
        struct ioat_dma_descriptor *hw;

        if (ioat_ring_space(ioat_chan) < 1) {
                dev_err(to_dev(ioat_chan),
                        "Unable to start null desc - ring full\n");
                return;
        }

        dev_dbg(to_dev(ioat_chan),
                "%s: head: %#x tail: %#x issued: %#x\n",
                __func__, ioat_chan->head, ioat_chan->tail, ioat_chan->issued);
        desc = ioat_get_ring_ent(ioat_chan, ioat_chan->head);

        hw = desc->hw;
        hw->ctl = 0;
        hw->ctl_f.null = 1;
        hw->ctl_f.int_en = 1;
        hw->ctl_f.compl_write = 1;
        /* set size to non-zero value (channel returns error when size is 0) */
        hw->size = NULL_DESC_BUFFER_SIZE;
        hw->src_addr = 0;
        hw->dst_addr = 0;
        async_tx_ack(&desc->txd);
        ioat_set_chainaddr(ioat_chan, desc->txd.phys);
        dump_desc_dbg(ioat_chan, desc);
        /* make sure descriptors are written before we submit */
        wmb();
        ioat_chan->head += 1;
        __ioat_issue_pending(ioat_chan);
}

void ioat_start_null_desc(struct ioatdma_chan *ioat_chan)
{
        spin_lock_bh(&ioat_chan->prep_lock);
        if (!test_bit(IOAT_CHAN_DOWN, &ioat_chan->state))
                __ioat_start_null_desc(ioat_chan);
        spin_unlock_bh(&ioat_chan->prep_lock);
}

static void __ioat_restart_chan(struct ioatdma_chan *ioat_chan)
{
        /* set the tail to be re-issued */
        ioat_chan->issued = ioat_chan->tail;
        ioat_chan->dmacount = 0;
        mod_timer(&ioat_chan->timer, jiffies + COMPLETION_TIMEOUT);

        dev_dbg(to_dev(ioat_chan),
                "%s: head: %#x tail: %#x issued: %#x count: %#x\n",
                __func__, ioat_chan->head, ioat_chan->tail,
                ioat_chan->issued, ioat_chan->dmacount);

        if (ioat_ring_pending(ioat_chan)) {
                struct ioat_ring_ent *desc;

                desc = ioat_get_ring_ent(ioat_chan, ioat_chan->tail);
                ioat_set_chainaddr(ioat_chan, desc->txd.phys);
                __ioat_issue_pending(ioat_chan);
        } else
                __ioat_start_null_desc(ioat_chan);
}

static int ioat_quiesce(struct ioatdma_chan *ioat_chan, unsigned long tmo)
{
        unsigned long end = jiffies + tmo;
        int err = 0;
        u32 status;

        status = ioat_chansts(ioat_chan);
        if (is_ioat_active(status) || is_ioat_idle(status))
                ioat_suspend(ioat_chan);
        while (is_ioat_active(status) || is_ioat_idle(status)) {
                if (tmo && time_after(jiffies, end)) {
                        err = -ETIMEDOUT;
                        break;
                }
                status = ioat_chansts(ioat_chan);
                cpu_relax();
        }

        return err;
}

static int ioat_reset_sync(struct ioatdma_chan *ioat_chan, unsigned long tmo)
{
        unsigned long end = jiffies + tmo;
        int err = 0;

        ioat_reset(ioat_chan);
        while (ioat_reset_pending(ioat_chan)) {
                if (end && time_after(jiffies, end)) {
                        err = -ETIMEDOUT;
                        break;
                }
                cpu_relax();
        }

        return err;
}

static dma_cookie_t ioat_tx_submit_unlock(struct dma_async_tx_descriptor *tx)
        __releases(&ioat_chan->prep_lock)
{
        struct dma_chan *c = tx->chan;
        struct ioatdma_chan *ioat_chan = to_ioat_chan(c);
        dma_cookie_t cookie;

        cookie = dma_cookie_assign(tx);
        dev_dbg(to_dev(ioat_chan), "%s: cookie: %d\n", __func__, cookie);

        if (!test_and_set_bit(IOAT_CHAN_ACTIVE, &ioat_chan->state))
                mod_timer(&ioat_chan->timer, jiffies + COMPLETION_TIMEOUT);

        /* make descriptor updates visible before advancing ioat->head,
         * this is purposefully not smp_wmb() since we are also
         * publishing the descriptor updates to a dma device
         */
        wmb();

        ioat_chan->head += ioat_chan->produce;

        ioat_update_pending(ioat_chan);
        spin_unlock_bh(&ioat_chan->prep_lock);

        return cookie;
}

static struct ioat_ring_ent *
ioat_alloc_ring_ent(struct dma_chan *chan, int idx, gfp_t flags)
{
        struct ioat_dma_descriptor *hw;
        struct ioat_ring_ent *desc;
        struct ioatdma_device *ioat_dma;
        struct ioatdma_chan *ioat_chan = to_ioat_chan(chan);
        int chunk;
        dma_addr_t phys;
        u8 *pos;
        off_t offs;

        ioat_dma = to_ioatdma_device(chan->device);

        chunk = idx / IOAT_DESCS_PER_2M;
        idx &= (IOAT_DESCS_PER_2M - 1);
        offs = idx * IOAT_DESC_SZ;
        pos = (u8 *)ioat_chan->descs[chunk].virt + offs;
        phys = ioat_chan->descs[chunk].hw + offs;
        hw = (struct ioat_dma_descriptor *)pos;
        memset(hw, 0, sizeof(*hw));

        desc = kmem_cache_zalloc(ioat_cache, flags);
        if (!desc)
                return NULL;

        dma_async_tx_descriptor_init(&desc->txd, chan);
        desc->txd.tx_submit = ioat_tx_submit_unlock;
        desc->hw = hw;
        desc->txd.phys = phys;
        return desc;
}

void ioat_free_ring_ent(struct ioat_ring_ent *desc, struct dma_chan *chan)
{
        kmem_cache_free(ioat_cache, desc);
}

struct ioat_ring_ent **
ioat_alloc_ring(struct dma_chan *c, int order, gfp_t flags)
{
        struct ioatdma_chan *ioat_chan = to_ioat_chan(c);
        struct ioat_ring_ent **ring;
        int total_descs = 1 << order;
        int i, chunks;

        /* allocate the array to hold the software ring */
        ring = kcalloc(total_descs, sizeof(*ring), flags);
        if (!ring)
                return NULL;

        ioat_chan->desc_chunks = chunks = (total_descs * IOAT_DESC_SZ) / SZ_2M;

        for (i = 0; i < chunks; i++) {
                struct ioat_descs *descs = &ioat_chan->descs[i];

                descs->virt = dma_alloc_coherent(to_dev(ioat_chan),
                                                 SZ_2M, &descs->hw, flags);
                if (!descs->virt && (i > 0)) {
                        int idx;

                        for (idx = 0; idx < i; idx++) {
                                dma_free_coherent(to_dev(ioat_chan), SZ_2M,
                                                  descs->virt, descs->hw);
                                descs->virt = NULL;
                                descs->hw = 0;
                        }

                        ioat_chan->desc_chunks = 0;
                        kfree(ring);
                        return NULL;
                }
        }

        for (i = 0; i < total_descs; i++) {
                ring[i] = ioat_alloc_ring_ent(c, i, flags);
                if (!ring[i]) {
                        int idx;

                        while (i--)
                                ioat_free_ring_ent(ring[i], c);

                        for (idx = 0; idx < ioat_chan->desc_chunks; idx++) {
                                dma_free_coherent(to_dev(ioat_chan),
                                                  SZ_2M,
                                                  ioat_chan->descs[idx].virt,
                                                  ioat_chan->descs[idx].hw);
                                ioat_chan->descs[idx].virt = NULL;
                                ioat_chan->descs[idx].hw = 0;
                        }

                        ioat_chan->desc_chunks = 0;
                        kfree(ring);
                        return NULL;
                }
                set_desc_id(ring[i], i);
        }

        /* link descs */
        for (i = 0; i < total_descs-1; i++) {
                struct ioat_ring_ent *next = ring[i+1];
                struct ioat_dma_descriptor *hw = ring[i]->hw;

                hw->next = next->txd.phys;
        }
        ring[i]->hw->next = ring[0]->txd.phys;

        return ring;
}

/**
 * ioat_check_space_lock - verify space and grab ring producer lock
 * @ioat: ioat,3 channel (ring) to operate on
 * @num_descs: allocation length
 */
int ioat_check_space_lock(struct ioatdma_chan *ioat_chan, int num_descs)
        __acquires(&ioat_chan->prep_lock)
{
        spin_lock_bh(&ioat_chan->prep_lock);
        /* never allow the last descriptor to be consumed, we need at
         * least one free at all times to allow for on-the-fly ring
         * resizing.
         */
        if (likely(ioat_ring_space(ioat_chan) > num_descs)) {
                dev_dbg(to_dev(ioat_chan), "%s: num_descs: %d (%x:%x:%x)\n",
                        __func__, num_descs, ioat_chan->head,
                        ioat_chan->tail, ioat_chan->issued);
                ioat_chan->produce = num_descs;
                return 0;  /* with ioat->prep_lock held */
        }
        spin_unlock_bh(&ioat_chan->prep_lock);

        dev_dbg_ratelimited(to_dev(ioat_chan),
                            "%s: ring full! num_descs: %d (%x:%x:%x)\n",
                            __func__, num_descs, ioat_chan->head,
                            ioat_chan->tail, ioat_chan->issued);

        /* progress reclaim in the allocation failure case we may be
         * called under bh_disabled so we need to trigger the timer
         * event directly
         */
        if (time_is_before_jiffies(ioat_chan->timer.expires)
            && timer_pending(&ioat_chan->timer)) {
                mod_timer(&ioat_chan->timer, jiffies + COMPLETION_TIMEOUT);
                ioat_timer_event((unsigned long)ioat_chan);
        }

        return -ENOMEM;
}

static bool desc_has_ext(struct ioat_ring_ent *desc)
{
        struct ioat_dma_descriptor *hw = desc->hw;

        if (hw->ctl_f.op == IOAT_OP_XOR ||
            hw->ctl_f.op == IOAT_OP_XOR_VAL) {
                struct ioat_xor_descriptor *xor = desc->xor;

                if (src_cnt_to_sw(xor->ctl_f.src_cnt) > 5)
                        return true;
        } else if (hw->ctl_f.op == IOAT_OP_PQ ||
                   hw->ctl_f.op == IOAT_OP_PQ_VAL) {
                struct ioat_pq_descriptor *pq = desc->pq;

                if (src_cnt_to_sw(pq->ctl_f.src_cnt) > 3)
                        return true;
        }

        return false;
}

static void
ioat_free_sed(struct ioatdma_device *ioat_dma, struct ioat_sed_ent *sed)
{
        if (!sed)
                return;

        dma_pool_free(ioat_dma->sed_hw_pool[sed->hw_pool], sed->hw, sed->dma);
        kmem_cache_free(ioat_sed_cache, sed);
}

static u64 ioat_get_current_completion(struct ioatdma_chan *ioat_chan)
{
        u64 phys_complete;
        u64 completion;

        completion = *ioat_chan->completion;
        phys_complete = ioat_chansts_to_addr(completion);

        dev_dbg(to_dev(ioat_chan), "%s: phys_complete: %#llx\n", __func__,
                (unsigned long long) phys_complete);

        return phys_complete;
}

static bool ioat_cleanup_preamble(struct ioatdma_chan *ioat_chan,
                                   u64 *phys_complete)
{
        *phys_complete = ioat_get_current_completion(ioat_chan);
        if (*phys_complete == ioat_chan->last_completion)
                return false;

        clear_bit(IOAT_COMPLETION_ACK, &ioat_chan->state);
        mod_timer(&ioat_chan->timer, jiffies + COMPLETION_TIMEOUT);

        return true;
}

static void
desc_get_errstat(struct ioatdma_chan *ioat_chan, struct ioat_ring_ent *desc)
{
        struct ioat_dma_descriptor *hw = desc->hw;

        switch (hw->ctl_f.op) {
        case IOAT_OP_PQ_VAL:
        case IOAT_OP_PQ_VAL_16S:
        {
                struct ioat_pq_descriptor *pq = desc->pq;

                /* check if there's error written */
                if (!pq->dwbes_f.wbes)
                        return;

                /* need to set a chanerr var for checking to clear later */

                if (pq->dwbes_f.p_val_err)
                        *desc->result |= SUM_CHECK_P_RESULT;

                if (pq->dwbes_f.q_val_err)
                        *desc->result |= SUM_CHECK_Q_RESULT;

                return;
        }
        default:
                return;
        }
}

/**
 * __cleanup - reclaim used descriptors
 * @ioat: channel (ring) to clean
 */
static void __cleanup(struct ioatdma_chan *ioat_chan, dma_addr_t phys_complete)
{
        struct ioatdma_device *ioat_dma = ioat_chan->ioat_dma;
        struct ioat_ring_ent *desc;
        bool seen_current = false;
        int idx = ioat_chan->tail, i;
        u16 active;

        dev_dbg(to_dev(ioat_chan), "%s: head: %#x tail: %#x issued: %#x\n",
                __func__, ioat_chan->head, ioat_chan->tail, ioat_chan->issued);

        /*
         * At restart of the channel, the completion address and the
         * channel status will be 0 due to starting a new chain. Since
         * it's new chain and the first descriptor "fails", there is
         * nothing to clean up. We do not want to reap the entire submitted
         * chain due to this 0 address value and then BUG.
         */
        if (!phys_complete)
                return;

        active = ioat_ring_active(ioat_chan);
        for (i = 0; i < active && !seen_current; i++) {
                struct dma_async_tx_descriptor *tx;

                smp_read_barrier_depends();
                prefetch(ioat_get_ring_ent(ioat_chan, idx + i + 1));
                desc = ioat_get_ring_ent(ioat_chan, idx + i);
                dump_desc_dbg(ioat_chan, desc);

                /* set err stat if we are using dwbes */
                if (ioat_dma->cap & IOAT_CAP_DWBES)
                        desc_get_errstat(ioat_chan, desc);

                tx = &desc->txd;
                if (tx->cookie) {
                        dma_cookie_complete(tx);
                        dma_descriptor_unmap(tx);
                        if (tx->callback) {
                                tx->callback(tx->callback_param);
                                tx->callback = NULL;
                        }
                }

                if (tx->phys == phys_complete)
                        seen_current = true;

                /* skip extended descriptors */
                if (desc_has_ext(desc)) {
                        BUG_ON(i + 1 >= active);
                        i++;
                }

                /* cleanup super extended descriptors */
                if (desc->sed) {
                        ioat_free_sed(ioat_dma, desc->sed);
                        desc->sed = NULL;
                }
        }

        /* finish all descriptor reads before incrementing tail */
        smp_mb();
        ioat_chan->tail = idx + i;
        /* no active descs have written a completion? */
        BUG_ON(active && !seen_current);
        ioat_chan->last_completion = phys_complete;

        if (active - i == 0) {
                dev_dbg(to_dev(ioat_chan), "%s: cancel completion timeout\n",
                        __func__);
                mod_timer(&ioat_chan->timer, jiffies + IDLE_TIMEOUT);
        }

        /* 5 microsecond delay per pending descriptor */
        writew(min((5 * (active - i)), IOAT_INTRDELAY_MASK),
               ioat_chan->ioat_dma->reg_base + IOAT_INTRDELAY_OFFSET);
}

static void ioat_cleanup(struct ioatdma_chan *ioat_chan)
{
        u64 phys_complete;

        spin_lock_bh(&ioat_chan->cleanup_lock);

        if (ioat_cleanup_preamble(ioat_chan, &phys_complete))
                __cleanup(ioat_chan, phys_complete);

        if (is_ioat_halted(*ioat_chan->completion)) {
                u32 chanerr = readl(ioat_chan->reg_base + IOAT_CHANERR_OFFSET);

                if (chanerr & IOAT_CHANERR_HANDLE_MASK) {
                        mod_timer(&ioat_chan->timer, jiffies + IDLE_TIMEOUT);
                        ioat_eh(ioat_chan);
                }
        }

        spin_unlock_bh(&ioat_chan->cleanup_lock);
}

void ioat_cleanup_event(unsigned long data)
{
        struct ioatdma_chan *ioat_chan = to_ioat_chan((void *)data);

        ioat_cleanup(ioat_chan);
        if (!test_bit(IOAT_RUN, &ioat_chan->state))
                return;
        writew(IOAT_CHANCTRL_RUN, ioat_chan->reg_base + IOAT_CHANCTRL_OFFSET);
}

static void ioat_restart_channel(struct ioatdma_chan *ioat_chan)
{
        u64 phys_complete;

        ioat_quiesce(ioat_chan, 0);
        if (ioat_cleanup_preamble(ioat_chan, &phys_complete))
                __cleanup(ioat_chan, phys_complete);

        __ioat_restart_chan(ioat_chan);
}

static void ioat_eh(struct ioatdma_chan *ioat_chan)
{
        struct pci_dev *pdev = to_pdev(ioat_chan);
        struct ioat_dma_descriptor *hw;
        struct dma_async_tx_descriptor *tx;
        u64 phys_complete;
        struct ioat_ring_ent *desc;
        u32 err_handled = 0;
        u32 chanerr_int;
        u32 chanerr;

        /* cleanup so tail points to descriptor that caused the error */
        if (ioat_cleanup_preamble(ioat_chan, &phys_complete))
                __cleanup(ioat_chan, phys_complete);

        chanerr = readl(ioat_chan->reg_base + IOAT_CHANERR_OFFSET);
        pci_read_config_dword(pdev, IOAT_PCI_CHANERR_INT_OFFSET, &chanerr_int);

        dev_dbg(to_dev(ioat_chan), "%s: error = %x:%x\n",
                __func__, chanerr, chanerr_int);

        desc = ioat_get_ring_ent(ioat_chan, ioat_chan->tail);
        hw = desc->hw;
        dump_desc_dbg(ioat_chan, desc);

        switch (hw->ctl_f.op) {
        case IOAT_OP_XOR_VAL:
                if (chanerr & IOAT_CHANERR_XOR_P_OR_CRC_ERR) {
                        *desc->result |= SUM_CHECK_P_RESULT;
                        err_handled |= IOAT_CHANERR_XOR_P_OR_CRC_ERR;
                }
                break;
        case IOAT_OP_PQ_VAL:
        case IOAT_OP_PQ_VAL_16S:
                if (chanerr & IOAT_CHANERR_XOR_P_OR_CRC_ERR) {
                        *desc->result |= SUM_CHECK_P_RESULT;
                        err_handled |= IOAT_CHANERR_XOR_P_OR_CRC_ERR;
                }
                if (chanerr & IOAT_CHANERR_XOR_Q_ERR) {
                        *desc->result |= SUM_CHECK_Q_RESULT;
                        err_handled |= IOAT_CHANERR_XOR_Q_ERR;
                }
                break;
        }

        /* fault on unhandled error or spurious halt */
        if (chanerr ^ err_handled || chanerr == 0) {
                dev_err(to_dev(ioat_chan), "%s: fatal error (%x:%x)\n",
                        __func__, chanerr, err_handled);
                BUG();
        } else { /* cleanup the faulty descriptor */
                tx = &desc->txd;
                if (tx->cookie) {
                        dma_cookie_complete(tx);
                        dma_descriptor_unmap(tx);
                        if (tx->callback) {
                                tx->callback(tx->callback_param);
                                tx->callback = NULL;
                        }
                }
        }

        writel(chanerr, ioat_chan->reg_base + IOAT_CHANERR_OFFSET);
        pci_write_config_dword(pdev, IOAT_PCI_CHANERR_INT_OFFSET, chanerr_int);

        /* mark faulting descriptor as complete */
        *ioat_chan->completion = desc->txd.phys;

        spin_lock_bh(&ioat_chan->prep_lock);
        ioat_restart_channel(ioat_chan);
        spin_unlock_bh(&ioat_chan->prep_lock);
}

static void check_active(struct ioatdma_chan *ioat_chan)
{
        if (ioat_ring_active(ioat_chan)) {
                mod_timer(&ioat_chan->timer, jiffies + COMPLETION_TIMEOUT);
                return;
        }

        if (test_and_clear_bit(IOAT_CHAN_ACTIVE, &ioat_chan->state))
                mod_timer(&ioat_chan->timer, jiffies + IDLE_TIMEOUT);
}

void ioat_timer_event(unsigned long data)
{
        struct ioatdma_chan *ioat_chan = to_ioat_chan((void *)data);
        dma_addr_t phys_complete;
        u64 status;

        status = ioat_chansts(ioat_chan);

        /* when halted due to errors check for channel
         * programming errors before advancing the completion state
         */
        if (is_ioat_halted(status)) {
                u32 chanerr;

                chanerr = readl(ioat_chan->reg_base + IOAT_CHANERR_OFFSET);
                dev_err(to_dev(ioat_chan), "%s: Channel halted (%x)\n",
                        __func__, chanerr);
                if (test_bit(IOAT_RUN, &ioat_chan->state))
                        BUG_ON(is_ioat_bug(chanerr));
                else /* we never got off the ground */
                        return;
        }

        spin_lock_bh(&ioat_chan->cleanup_lock);

        /* handle the no-actives case */
        if (!ioat_ring_active(ioat_chan)) {
                spin_lock_bh(&ioat_chan->prep_lock);
                check_active(ioat_chan);
                spin_unlock_bh(&ioat_chan->prep_lock);
                spin_unlock_bh(&ioat_chan->cleanup_lock);
                return;
        }

        /* if we haven't made progress and we have already
         * acknowledged a pending completion once, then be more
         * forceful with a restart
         */
        if (ioat_cleanup_preamble(ioat_chan, &phys_complete))
                __cleanup(ioat_chan, phys_complete);
        else if (test_bit(IOAT_COMPLETION_ACK, &ioat_chan->state)) {
                u32 chanerr;

                chanerr = readl(ioat_chan->reg_base + IOAT_CHANERR_OFFSET);
                dev_warn(to_dev(ioat_chan), "Restarting channel...\n");
                dev_warn(to_dev(ioat_chan), "CHANSTS: %#Lx CHANERR: %#x\n",
                         status, chanerr);
                dev_warn(to_dev(ioat_chan), "Active descriptors: %d\n",
                         ioat_ring_active(ioat_chan));

                spin_lock_bh(&ioat_chan->prep_lock);
                ioat_restart_channel(ioat_chan);
                spin_unlock_bh(&ioat_chan->prep_lock);
                spin_unlock_bh(&ioat_chan->cleanup_lock);
                return;
        } else
                set_bit(IOAT_COMPLETION_ACK, &ioat_chan->state);

        mod_timer(&ioat_chan->timer, jiffies + COMPLETION_TIMEOUT);
        spin_unlock_bh(&ioat_chan->cleanup_lock);
}

enum dma_status
ioat_tx_status(struct dma_chan *c, dma_cookie_t cookie,
                struct dma_tx_state *txstate)
{
        struct ioatdma_chan *ioat_chan = to_ioat_chan(c);
        enum dma_status ret;

        ret = dma_cookie_status(c, cookie, txstate);
        if (ret == DMA_COMPLETE)
                return ret;

        ioat_cleanup(ioat_chan);

        return dma_cookie_status(c, cookie, txstate);
}

int ioat_reset_hw(struct ioatdma_chan *ioat_chan)
{
        /* throw away whatever the channel was doing and get it
         * initialized, with ioat3 specific workarounds
         */
        struct ioatdma_device *ioat_dma = ioat_chan->ioat_dma;
        struct pci_dev *pdev = ioat_dma->pdev;
        u32 chanerr;
        u16 dev_id;
        int err;

        ioat_quiesce(ioat_chan, msecs_to_jiffies(100));

        chanerr = readl(ioat_chan->reg_base + IOAT_CHANERR_OFFSET);
        writel(chanerr, ioat_chan->reg_base + IOAT_CHANERR_OFFSET);

        if (ioat_dma->version < IOAT_VER_3_3) {
                /* clear any pending errors */
                err = pci_read_config_dword(pdev,
                                IOAT_PCI_CHANERR_INT_OFFSET, &chanerr);
                if (err) {
                        dev_err(&pdev->dev,
                                "channel error register unreachable\n");
                        return err;
                }
                pci_write_config_dword(pdev,
                                IOAT_PCI_CHANERR_INT_OFFSET, chanerr);

                /* Clear DMAUNCERRSTS Cfg-Reg Parity Error status bit
                 * (workaround for spurious config parity error after restart)
                 */
                pci_read_config_word(pdev, IOAT_PCI_DEVICE_ID_OFFSET, &dev_id);
                if (dev_id == PCI_DEVICE_ID_INTEL_IOAT_TBG0) {
                        pci_write_config_dword(pdev,
                                               IOAT_PCI_DMAUNCERRSTS_OFFSET,
                                               0x10);
                }
        }

        if (is_bwd_ioat(pdev) && (ioat_dma->irq_mode == IOAT_MSIX)) {
                ioat_dma->msixtba0 = readq(ioat_dma->reg_base + 0x1000);
                ioat_dma->msixdata0 = readq(ioat_dma->reg_base + 0x1008);
                ioat_dma->msixpba = readq(ioat_dma->reg_base + 0x1800);
        }


        err = ioat_reset_sync(ioat_chan, msecs_to_jiffies(200));
        if (!err) {
                if (is_bwd_ioat(pdev) && (ioat_dma->irq_mode == IOAT_MSIX)) {
                        writeq(ioat_dma->msixtba0, ioat_dma->reg_base + 0x1000);
                        writeq(ioat_dma->msixdata0, ioat_dma->reg_base + 0x1008);
                        writeq(ioat_dma->msixpba, ioat_dma->reg_base + 0x1800);
                }
        }

        if (err)
                dev_err(&pdev->dev, "Failed to reset: %d\n", err);

        return err;
}