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 "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, gfp_t flags)
{
	struct ioat_dma_descriptor *hw;
	struct ioat_ring_ent *desc;
	struct ioatdma_device *ioat_dma;
	dma_addr_t phys;

	ioat_dma = to_ioatdma_device(chan->device);
	hw = dma_pool_alloc(ioat_dma->dma_pool, flags, &phys);
	if (!hw)
		return NULL;
	memset(hw, 0, sizeof(*hw));

	desc = kmem_cache_zalloc(ioat_cache, flags);
	if (!desc) {
		dma_pool_free(ioat_dma->dma_pool, hw, phys);
		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)
{
	struct ioatdma_device *ioat_dma;

	ioat_dma = to_ioatdma_device(chan->device);
	dma_pool_free(ioat_dma->dma_pool, desc->hw, desc->txd.phys);
	kmem_cache_free(ioat_cache, desc);
}

struct ioat_ring_ent **
ioat_alloc_ring(struct dma_chan *c, int order, gfp_t flags)
{
	struct ioat_ring_ent **ring;
	int descs = 1 << order;
	int i;

	/* allocate the array to hold the software ring */
	ring = kcalloc(descs, sizeof(*ring), flags);
	if (!ring)
		return NULL;
	for (i = 0; i < descs; i++) {
		ring[i] = ioat_alloc_ring_ent(c, flags);
		if (!ring[i]) {
			while (i--)
				ioat_free_ring_ent(ring[i], c);
			kfree(ring);
			return NULL;
		}
		set_desc_id(ring[i], i);
	}

	/* link descs */
	for (i = 0; i < 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;
	}

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


	if (ioat_ring_active(ioat_chan))
		mod_timer(&ioat_chan->timer, jiffies + COMPLETION_TIMEOUT);
	else {
		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);
}

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);
}

static int ioat_irq_reinit(struct ioatdma_device *ioat_dma)
{
	struct pci_dev *pdev = ioat_dma->pdev;
	int irq = pdev->irq, i;

	if (!is_bwd_ioat(pdev))
		return 0;

	switch (ioat_dma->irq_mode) {
	case IOAT_MSIX:
		for (i = 0; i < ioat_dma->dma_dev.chancnt; i++) {
			struct msix_entry *msix = &ioat_dma->msix_entries[i];
			struct ioatdma_chan *ioat_chan;

			ioat_chan = ioat_chan_by_index(ioat_dma, i);
			devm_free_irq(&pdev->dev, msix->vector, ioat_chan);
		}

		pci_disable_msix(pdev);
		break;
	case IOAT_MSI:
		pci_disable_msi(pdev);
		/* fall through */
	case IOAT_INTX:
		devm_free_irq(&pdev->dev, irq, ioat_dma);
		break;
	default:
		return 0;
	}
	ioat_dma->irq_mode = IOAT_NOIRQ;

	return ioat_dma_setup_interrupts(ioat_dma);
}

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);
		}
	}

	err = ioat_reset_sync(ioat_chan, msecs_to_jiffies(200));
	if (!err)
		err = ioat_irq_reinit(ioat_dma);

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

	return err;
}