/*
 * Intel I/OAT DMA Linux driver
 * Copyright(c) 2004 - 2007 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.
 *
 * You should have received a copy of the GNU General Public License along with
 * this program; if not, write to the Free Software Foundation, Inc.,
 * 51 Franklin St - Fifth Floor, Boston, MA 02110-1301 USA.
 *
 * 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/pci.h>
#include <linux/interrupt.h>
#include <linux/dmaengine.h>
#include <linux/delay.h>
#include <linux/dma-mapping.h>
#include "ioatdma.h"
#include "ioatdma_registers.h"
#include "ioatdma_hw.h"

#define to_ioat_chan(chan) container_of(chan, struct ioat_dma_chan, common)
#define to_ioatdma_device(dev) container_of(dev, struct ioatdma_device, common)
#define to_ioat_desc(lh) container_of(lh, struct ioat_desc_sw, node)
#define tx_to_ioat_desc(tx) container_of(tx, struct ioat_desc_sw, async_tx)

static int ioat_pending_level = 4;
module_param(ioat_pending_level, int, 0644);
MODULE_PARM_DESC(ioat_pending_level,
                 "high-water mark for pushing ioat descriptors (default: 4)");

/* internal functions */
static void ioat_dma_start_null_desc(struct ioat_dma_chan *ioat_chan);
static void ioat_dma_memcpy_cleanup(struct ioat_dma_chan *ioat_chan);

static struct ioat_desc_sw *
ioat1_dma_get_next_descriptor(struct ioat_dma_chan *ioat_chan);
static struct ioat_desc_sw *
ioat2_dma_get_next_descriptor(struct ioat_dma_chan *ioat_chan);

static inline struct ioat_dma_chan *ioat_lookup_chan_by_index(
                                                struct ioatdma_device *device,
                                                int index)
{
        return device->idx[index];
}

/**
 * ioat_dma_do_interrupt - handler used for single vector interrupt mode
 * @irq: interrupt id
 * @data: interrupt data
 */
static irqreturn_t ioat_dma_do_interrupt(int irq, void *data)
{
        struct ioatdma_device *instance = data;
        struct ioat_dma_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_bit(bit, &attnstatus, BITS_PER_LONG) {
                ioat_chan = ioat_lookup_chan_by_index(instance, bit);
                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
 */
static irqreturn_t ioat_dma_do_interrupt_msix(int irq, void *data)
{
        struct ioat_dma_chan *ioat_chan = data;

        tasklet_schedule(&ioat_chan->cleanup_task);

        return IRQ_HANDLED;
}

static void ioat_dma_cleanup_tasklet(unsigned long data);

/**
 * ioat_dma_enumerate_channels - find and initialize the device's channels
 * @device: the device to be enumerated
 */
static int ioat_dma_enumerate_channels(struct ioatdma_device *device)
{
        u8 xfercap_scale;
        u32 xfercap;
        int i;
        struct ioat_dma_chan *ioat_chan;

        device->common.chancnt = readb(device->reg_base + IOAT_CHANCNT_OFFSET);
        xfercap_scale = readb(device->reg_base + IOAT_XFERCAP_OFFSET);
        xfercap = (xfercap_scale == 0 ? -1 : (1UL << xfercap_scale));

        for (i = 0; i < device->common.chancnt; i++) {
                ioat_chan = kzalloc(sizeof(*ioat_chan), GFP_KERNEL);
                if (!ioat_chan) {
                        device->common.chancnt = i;
                        break;
                }

                ioat_chan->device = device;
                ioat_chan->reg_base = device->reg_base + (0x80 * (i + 1));
                ioat_chan->xfercap = xfercap;
                ioat_chan->desccount = 0;
                if (ioat_chan->device->version != IOAT_VER_1_2) {
                        writel(IOAT_DCACTRL_CMPL_WRITE_ENABLE
                                        | IOAT_DMA_DCA_ANY_CPU,
                                ioat_chan->reg_base + IOAT_DCACTRL_OFFSET);
                }
                spin_lock_init(&ioat_chan->cleanup_lock);
                spin_lock_init(&ioat_chan->desc_lock);
                INIT_LIST_HEAD(&ioat_chan->free_desc);
                INIT_LIST_HEAD(&ioat_chan->used_desc);
                /* This should be made common somewhere in dmaengine.c */
                ioat_chan->common.device = &device->common;
                list_add_tail(&ioat_chan->common.device_node,
                              &device->common.channels);
                device->idx[i] = ioat_chan;
                tasklet_init(&ioat_chan->cleanup_task,
                             ioat_dma_cleanup_tasklet,
                             (unsigned long) ioat_chan);
                tasklet_disable(&ioat_chan->cleanup_task);
        }
        return device->common.chancnt;
}

static void ioat_set_src(dma_addr_t addr,
                         struct dma_async_tx_descriptor *tx,
                         int index)
{
        tx_to_ioat_desc(tx)->src = addr;
}

static void ioat_set_dest(dma_addr_t addr,
                          struct dma_async_tx_descriptor *tx,
                          int index)
{
        tx_to_ioat_desc(tx)->dst = addr;
}

/**
 * ioat_dma_memcpy_issue_pending - push potentially unrecognized appended
 *                                 descriptors to hw
 * @chan: DMA channel handle
 */
static inline void __ioat1_dma_memcpy_issue_pending(
                                                struct ioat_dma_chan *ioat_chan)
{
        ioat_chan->pending = 0;
        writeb(IOAT_CHANCMD_APPEND, ioat_chan->reg_base + IOAT1_CHANCMD_OFFSET);
}

static void ioat1_dma_memcpy_issue_pending(struct dma_chan *chan)
{
        struct ioat_dma_chan *ioat_chan = to_ioat_chan(chan);

        if (ioat_chan->pending != 0) {
                spin_lock_bh(&ioat_chan->desc_lock);
                __ioat1_dma_memcpy_issue_pending(ioat_chan);
                spin_unlock_bh(&ioat_chan->desc_lock);
        }
}

static inline void __ioat2_dma_memcpy_issue_pending(
                                                struct ioat_dma_chan *ioat_chan)
{
        ioat_chan->pending = 0;
        writew(ioat_chan->dmacount,
               ioat_chan->reg_base + IOAT_CHAN_DMACOUNT_OFFSET);
}

static void ioat2_dma_memcpy_issue_pending(struct dma_chan *chan)
{
        struct ioat_dma_chan *ioat_chan = to_ioat_chan(chan);

        if (ioat_chan->pending != 0) {
                spin_lock_bh(&ioat_chan->desc_lock);
                __ioat2_dma_memcpy_issue_pending(ioat_chan);
                spin_unlock_bh(&ioat_chan->desc_lock);
        }
}

static dma_cookie_t ioat1_tx_submit(struct dma_async_tx_descriptor *tx)
{
        struct ioat_dma_chan *ioat_chan = to_ioat_chan(tx->chan);
        struct ioat_desc_sw *first = tx_to_ioat_desc(tx);
        struct ioat_desc_sw *prev, *new;
        struct ioat_dma_descriptor *hw;
        dma_cookie_t cookie;
        LIST_HEAD(new_chain);
        u32 copy;
        size_t len;
        dma_addr_t src, dst;
        int orig_ack;
        unsigned int desc_count = 0;

        /* src and dest and len are stored in the initial descriptor */
        len = first->len;
        src = first->src;
        dst = first->dst;
        orig_ack = first->async_tx.ack;
        new = first;

        spin_lock_bh(&ioat_chan->desc_lock);
        prev = to_ioat_desc(ioat_chan->used_desc.prev);
        prefetch(prev->hw);
        do {
                copy = min_t(size_t, len, ioat_chan->xfercap);

                new->async_tx.ack = 1;

                hw = new->hw;
                hw->size = copy;
                hw->ctl = 0;
                hw->src_addr = src;
                hw->dst_addr = dst;
                hw->next = 0;

                /* chain together the physical address list for the HW */
                wmb();
                prev->hw->next = (u64) new->async_tx.phys;

                len -= copy;
                dst += copy;
                src += copy;

                list_add_tail(&new->node, &new_chain);
                desc_count++;
                prev = new;
        } while (len && (new = ioat1_dma_get_next_descriptor(ioat_chan)));

        hw->ctl = IOAT_DMA_DESCRIPTOR_CTL_CP_STS;
        if (new->async_tx.callback) {
                hw->ctl |= IOAT_DMA_DESCRIPTOR_CTL_INT_GN;
                if (first != new) {
                        /* move callback into to last desc */
                        new->async_tx.callback = first->async_tx.callback;
                        new->async_tx.callback_param
                                        = first->async_tx.callback_param;
                        first->async_tx.callback = NULL;
                        first->async_tx.callback_param = NULL;
                }
        }

        new->tx_cnt = desc_count;
        new->async_tx.ack = orig_ack; /* client is in control of this ack */

        /* store the original values for use in later cleanup */
        if (new != first) {
                new->src = first->src;
                new->dst = first->dst;
                new->len = first->len;
        }

        /* cookie incr and addition to used_list must be atomic */
        cookie = ioat_chan->common.cookie;
        cookie++;
        if (cookie < 0)
                cookie = 1;
        ioat_chan->common.cookie = new->async_tx.cookie = cookie;

        /* write address into NextDescriptor field of last desc in chain */
        to_ioat_desc(ioat_chan->used_desc.prev)->hw->next =
                                                        first->async_tx.phys;
        __list_splice(&new_chain, ioat_chan->used_desc.prev);

        ioat_chan->dmacount += desc_count;
        ioat_chan->pending += desc_count;
        if (ioat_chan->pending >= ioat_pending_level)
                __ioat1_dma_memcpy_issue_pending(ioat_chan);
        spin_unlock_bh(&ioat_chan->desc_lock);

        return cookie;
}

static dma_cookie_t ioat2_tx_submit(struct dma_async_tx_descriptor *tx)
{
        struct ioat_dma_chan *ioat_chan = to_ioat_chan(tx->chan);
        struct ioat_desc_sw *first = tx_to_ioat_desc(tx);
        struct ioat_desc_sw *new;
        struct ioat_dma_descriptor *hw;
        dma_cookie_t cookie;
        u32 copy;
        size_t len;
        dma_addr_t src, dst;
        int orig_ack;
        unsigned int desc_count = 0;

        /* src and dest and len are stored in the initial descriptor */
        len = first->len;
        src = first->src;
        dst = first->dst;
        orig_ack = first->async_tx.ack;
        new = first;

        /*
         * ioat_chan->desc_lock is still in force in version 2 path
         * it gets unlocked at end of this function
         */
        do {
                copy = min_t(size_t, len, ioat_chan->xfercap);

                new->async_tx.ack = 1;

                hw = new->hw;
                hw->size = copy;
                hw->ctl = 0;
                hw->src_addr = src;
                hw->dst_addr = dst;

                len -= copy;
                dst += copy;
                src += copy;
                desc_count++;
        } while (len && (new = ioat2_dma_get_next_descriptor(ioat_chan)));

        hw->ctl = IOAT_DMA_DESCRIPTOR_CTL_CP_STS;
        if (new->async_tx.callback) {
                hw->ctl |= IOAT_DMA_DESCRIPTOR_CTL_INT_GN;
                if (first != new) {
                        /* move callback into to last desc */
                        new->async_tx.callback = first->async_tx.callback;
                        new->async_tx.callback_param
                                        = first->async_tx.callback_param;
                        first->async_tx.callback = NULL;
                        first->async_tx.callback_param = NULL;
                }
        }

        new->tx_cnt = desc_count;
        new->async_tx.ack = orig_ack; /* client is in control of this ack */

        /* store the original values for use in later cleanup */
        if (new != first) {
                new->src = first->src;
                new->dst = first->dst;
                new->len = first->len;
        }

        /* cookie incr and addition to used_list must be atomic */
        cookie = ioat_chan->common.cookie;
        cookie++;
        if (cookie < 0)
                cookie = 1;
        ioat_chan->common.cookie = new->async_tx.cookie = cookie;

        ioat_chan->dmacount += desc_count;
        ioat_chan->pending += desc_count;
        if (ioat_chan->pending >= ioat_pending_level)
                __ioat2_dma_memcpy_issue_pending(ioat_chan);
        spin_unlock_bh(&ioat_chan->desc_lock);

        return cookie;
}

/**
 * ioat_dma_alloc_descriptor - allocate and return a sw and hw descriptor pair
 * @ioat_chan: the channel supplying the memory pool for the descriptors
 * @flags: allocation flags
 */
static struct ioat_desc_sw *ioat_dma_alloc_descriptor(
                                        struct ioat_dma_chan *ioat_chan,
                                        gfp_t flags)
{
        struct ioat_dma_descriptor *desc;
        struct ioat_desc_sw *desc_sw;
        struct ioatdma_device *ioatdma_device;
        dma_addr_t phys;

        ioatdma_device = to_ioatdma_device(ioat_chan->common.device);
        desc = pci_pool_alloc(ioatdma_device->dma_pool, flags, &phys);
        if (unlikely(!desc))
                return NULL;

        desc_sw = kzalloc(sizeof(*desc_sw), flags);
        if (unlikely(!desc_sw)) {
                pci_pool_free(ioatdma_device->dma_pool, desc, phys);
                return NULL;
        }

        memset(desc, 0, sizeof(*desc));
        dma_async_tx_descriptor_init(&desc_sw->async_tx, &ioat_chan->common);
        desc_sw->async_tx.tx_set_src = ioat_set_src;
        desc_sw->async_tx.tx_set_dest = ioat_set_dest;
        switch (ioat_chan->device->version) {
        case IOAT_VER_1_2:
                desc_sw->async_tx.tx_submit = ioat1_tx_submit;
                break;
        case IOAT_VER_2_0:
                desc_sw->async_tx.tx_submit = ioat2_tx_submit;
                break;
        }
        INIT_LIST_HEAD(&desc_sw->async_tx.tx_list);

        desc_sw->hw = desc;
        desc_sw->async_tx.phys = phys;

        return desc_sw;
}

static int ioat_initial_desc_count = 256;
module_param(ioat_initial_desc_count, int, 0644);
MODULE_PARM_DESC(ioat_initial_desc_count,
                 "initial descriptors per channel (default: 256)");

/**
 * ioat2_dma_massage_chan_desc - link the descriptors into a circle
 * @ioat_chan: the channel to be massaged
 */
static void ioat2_dma_massage_chan_desc(struct ioat_dma_chan *ioat_chan)
{
        struct ioat_desc_sw *desc, *_desc;

        /* setup used_desc */
        ioat_chan->used_desc.next = ioat_chan->free_desc.next;
        ioat_chan->used_desc.prev = NULL;

        /* pull free_desc out of the circle so that every node is a hw
         * descriptor, but leave it pointing to the list
         */
        ioat_chan->free_desc.prev->next = ioat_chan->free_desc.next;
        ioat_chan->free_desc.next->prev = ioat_chan->free_desc.prev;

        /* circle link the hw descriptors */
        desc = to_ioat_desc(ioat_chan->free_desc.next);
        desc->hw->next = to_ioat_desc(desc->node.next)->async_tx.phys;
        list_for_each_entry_safe(desc, _desc, ioat_chan->free_desc.next, node) {
                desc->hw->next = to_ioat_desc(desc->node.next)->async_tx.phys;
        }
}

/**
 * ioat_dma_alloc_chan_resources - returns the number of allocated descriptors
 * @chan: the channel to be filled out
 */
static int ioat_dma_alloc_chan_resources(struct dma_chan *chan)
{
        struct ioat_dma_chan *ioat_chan = to_ioat_chan(chan);
        struct ioat_desc_sw *desc;
        u16 chanctrl;
        u32 chanerr;
        int i;
        LIST_HEAD(tmp_list);

        /* have we already been set up? */
        if (!list_empty(&ioat_chan->free_desc))
                return ioat_chan->desccount;

        /* Setup register to interrupt and write completion status on error */
        chanctrl = IOAT_CHANCTRL_ERR_INT_EN |
                IOAT_CHANCTRL_ANY_ERR_ABORT_EN |
                IOAT_CHANCTRL_ERR_COMPLETION_EN;
        writew(chanctrl, ioat_chan->reg_base + IOAT_CHANCTRL_OFFSET);

        chanerr = readl(ioat_chan->reg_base + IOAT_CHANERR_OFFSET);
        if (chanerr) {
                dev_err(&ioat_chan->device->pdev->dev,
                        "CHANERR = %x, clearing\n", chanerr);
                writel(chanerr, ioat_chan->reg_base + IOAT_CHANERR_OFFSET);
        }

        /* Allocate descriptors */
        for (i = 0; i < ioat_initial_desc_count; i++) {
                desc = ioat_dma_alloc_descriptor(ioat_chan, GFP_KERNEL);
                if (!desc) {
                        dev_err(&ioat_chan->device->pdev->dev,
                                "Only %d initial descriptors\n", i);
                        break;
                }
                list_add_tail(&desc->node, &tmp_list);
        }
        spin_lock_bh(&ioat_chan->desc_lock);
        ioat_chan->desccount = i;
        list_splice(&tmp_list, &ioat_chan->free_desc);
        if (ioat_chan->device->version != IOAT_VER_1_2)
                ioat2_dma_massage_chan_desc(ioat_chan);
        spin_unlock_bh(&ioat_chan->desc_lock);

        /* allocate a completion writeback area */
        /* doing 2 32bit writes to mmio since 1 64b write doesn't work */
        ioat_chan->completion_virt =
                pci_pool_alloc(ioat_chan->device->completion_pool,
                               GFP_KERNEL,
                               &ioat_chan->completion_addr);
        memset(ioat_chan->completion_virt, 0,
               sizeof(*ioat_chan->completion_virt));
        writel(((u64) ioat_chan->completion_addr) & 0x00000000FFFFFFFF,
               ioat_chan->reg_base + IOAT_CHANCMP_OFFSET_LOW);
        writel(((u64) ioat_chan->completion_addr) >> 32,
               ioat_chan->reg_base + IOAT_CHANCMP_OFFSET_HIGH);

        tasklet_enable(&ioat_chan->cleanup_task);
        ioat_dma_start_null_desc(ioat_chan);  /* give chain to dma device */
        return ioat_chan->desccount;
}

/**
 * ioat_dma_free_chan_resources - release all the descriptors
 * @chan: the channel to be cleaned
 */
static void ioat_dma_free_chan_resources(struct dma_chan *chan)
{
        struct ioat_dma_chan *ioat_chan = to_ioat_chan(chan);
        struct ioatdma_device *ioatdma_device = to_ioatdma_device(chan->device);
        struct ioat_desc_sw *desc, *_desc;
        int in_use_descs = 0;

        tasklet_disable(&ioat_chan->cleanup_task);
        ioat_dma_memcpy_cleanup(ioat_chan);

        /* Delay 100ms after reset to allow internal DMA logic to quiesce
         * before removing DMA descriptor resources.
         */
        writeb(IOAT_CHANCMD_RESET,
               ioat_chan->reg_base
                        + IOAT_CHANCMD_OFFSET(ioat_chan->device->version));
        mdelay(100);

        spin_lock_bh(&ioat_chan->desc_lock);
        switch (ioat_chan->device->version) {
        case IOAT_VER_1_2:
                list_for_each_entry_safe(desc, _desc,
                                         &ioat_chan->used_desc, node) {
                        in_use_descs++;
                        list_del(&desc->node);
                        pci_pool_free(ioatdma_device->dma_pool, desc->hw,
                                      desc->async_tx.phys);
                        kfree(desc);
                }
                list_for_each_entry_safe(desc, _desc,
                                         &ioat_chan->free_desc, node) {
                        list_del(&desc->node);
                        pci_pool_free(ioatdma_device->dma_pool, desc->hw,
                                      desc->async_tx.phys);
                        kfree(desc);
                }
                break;
        case IOAT_VER_2_0:
                list_for_each_entry_safe(desc, _desc,
                                         ioat_chan->free_desc.next, node) {
                        list_del(&desc->node);
                        pci_pool_free(ioatdma_device->dma_pool, desc->hw,
                                      desc->async_tx.phys);
                        kfree(desc);
                }
                desc = to_ioat_desc(ioat_chan->free_desc.next);
                pci_pool_free(ioatdma_device->dma_pool, desc->hw,
                              desc->async_tx.phys);
                kfree(desc);
                INIT_LIST_HEAD(&ioat_chan->free_desc);
                INIT_LIST_HEAD(&ioat_chan->used_desc);
                break;
        }
        spin_unlock_bh(&ioat_chan->desc_lock);

        pci_pool_free(ioatdma_device->completion_pool,
                      ioat_chan->completion_virt,
                      ioat_chan->completion_addr);

        /* one is ok since we left it on there on purpose */
        if (in_use_descs > 1)
                dev_err(&ioat_chan->device->pdev->dev,
                        "Freeing %d in use descriptors!\n",
                        in_use_descs - 1);

        ioat_chan->last_completion = ioat_chan->completion_addr = 0;
        ioat_chan->pending = 0;
        ioat_chan->dmacount = 0;
}

/**
 * ioat_dma_get_next_descriptor - return the next available descriptor
 * @ioat_chan: IOAT DMA channel handle
 *
 * Gets the next descriptor from the chain, and must be called with the
 * channel's desc_lock held.  Allocates more descriptors if the channel
 * has run out.
 */
static struct ioat_desc_sw *
ioat1_dma_get_next_descriptor(struct ioat_dma_chan *ioat_chan)
{
        struct ioat_desc_sw *new;

        if (!list_empty(&ioat_chan->free_desc)) {
                new = to_ioat_desc(ioat_chan->free_desc.next);
                list_del(&new->node);
        } else {
                /* try to get another desc */
                new = ioat_dma_alloc_descriptor(ioat_chan, GFP_ATOMIC);
                if (!new) {
                        dev_err(&ioat_chan->device->pdev->dev,
                                "alloc failed\n");
                        return NULL;
                }
        }

        prefetch(new->hw);
        return new;
}

static struct ioat_desc_sw *
ioat2_dma_get_next_descriptor(struct ioat_dma_chan *ioat_chan)
{
        struct ioat_desc_sw *new;

        /*
         * used.prev points to where to start processing
         * used.next points to next free descriptor
         * if used.prev == NULL, there are none waiting to be processed
         * if used.next == used.prev.prev, there is only one free descriptor,
         *      and we need to use it to as a noop descriptor before
         *      linking in a new set of descriptors, since the device
         *      has probably already read the pointer to it
         */
        if (ioat_chan->used_desc.prev &&
            ioat_chan->used_desc.next == ioat_chan->used_desc.prev->prev) {

                struct ioat_desc_sw *desc;
                struct ioat_desc_sw *noop_desc;
                int i;

                /* set up the noop descriptor */
                noop_desc = to_ioat_desc(ioat_chan->used_desc.next);
                noop_desc->hw->size = 0;
                noop_desc->hw->ctl = IOAT_DMA_DESCRIPTOR_NUL;
                noop_desc->hw->src_addr = 0;
                noop_desc->hw->dst_addr = 0;

                ioat_chan->used_desc.next = ioat_chan->used_desc.next->next;
                ioat_chan->pending++;
                ioat_chan->dmacount++;

                /* try to get a few more descriptors */
                for (i = 16; i; i--) {
                        desc = ioat_dma_alloc_descriptor(ioat_chan, GFP_ATOMIC);
                        if (!desc) {
                                dev_err(&ioat_chan->device->pdev->dev,
                                        "alloc failed\n");
                                break;
                        }
                        list_add_tail(&desc->node, ioat_chan->used_desc.next);

                        desc->hw->next
                                = to_ioat_desc(desc->node.next)->async_tx.phys;
                        to_ioat_desc(desc->node.prev)->hw->next
                                = desc->async_tx.phys;
                        ioat_chan->desccount++;
                }

                ioat_chan->used_desc.next = noop_desc->node.next;
        }
        new = to_ioat_desc(ioat_chan->used_desc.next);
        prefetch(new);
        ioat_chan->used_desc.next = new->node.next;

        if (ioat_chan->used_desc.prev == NULL)
                ioat_chan->used_desc.prev = &new->node;

        prefetch(new->hw);
        return new;
}

static struct ioat_desc_sw *ioat_dma_get_next_descriptor(
                                                struct ioat_dma_chan *ioat_chan)
{
        if (!ioat_chan)
                return NULL;

        switch (ioat_chan->device->version) {
        case IOAT_VER_1_2:
                return ioat1_dma_get_next_descriptor(ioat_chan);
                break;
        case IOAT_VER_2_0:
                return ioat2_dma_get_next_descriptor(ioat_chan);
                break;
        }
        return NULL;
}

static struct dma_async_tx_descriptor *ioat1_dma_prep_memcpy(
                                                struct dma_chan *chan,
                                                size_t len,
                                                int int_en)
{
        struct ioat_dma_chan *ioat_chan = to_ioat_chan(chan);
        struct ioat_desc_sw *new;

        spin_lock_bh(&ioat_chan->desc_lock);
        new = ioat_dma_get_next_descriptor(ioat_chan);
        spin_unlock_bh(&ioat_chan->desc_lock);

        if (new) {
                new->len = len;
                return &new->async_tx;
        } else
                return NULL;
}

static struct dma_async_tx_descriptor *ioat2_dma_prep_memcpy(
                                                struct dma_chan *chan,
                                                size_t len,
                                                int int_en)
{
        struct ioat_dma_chan *ioat_chan = to_ioat_chan(chan);
        struct ioat_desc_sw *new;

        spin_lock_bh(&ioat_chan->desc_lock);
        new = ioat2_dma_get_next_descriptor(ioat_chan);

        /*
         * leave ioat_chan->desc_lock set in ioat 2 path
         * it will get unlocked at end of tx_submit
         */

        if (new) {
                new->len = len;
                return &new->async_tx;
        } else
                return NULL;
}

static void ioat_dma_cleanup_tasklet(unsigned long data)
{
        struct ioat_dma_chan *chan = (void *)data;
        ioat_dma_memcpy_cleanup(chan);
        writew(IOAT_CHANCTRL_INT_DISABLE,
               chan->reg_base + IOAT_CHANCTRL_OFFSET);
}

/**
 * ioat_dma_memcpy_cleanup - cleanup up finished descriptors
 * @chan: ioat channel to be cleaned up
 */
static void ioat_dma_memcpy_cleanup(struct ioat_dma_chan *ioat_chan)
{
        unsigned long phys_complete;
        struct ioat_desc_sw *desc, *_desc;
        dma_cookie_t cookie = 0;
        unsigned long desc_phys;
        struct ioat_desc_sw *latest_desc;

        prefetch(ioat_chan->completion_virt);

        if (!spin_trylock_bh(&ioat_chan->cleanup_lock))
                return;

        /* The completion writeback can happen at any time,
           so reads by the driver need to be atomic operations
           The descriptor physical addresses are limited to 32-bits
           when the CPU can only do a 32-bit mov */

#if (BITS_PER_LONG == 64)
        phys_complete =
                ioat_chan->completion_virt->full
                & IOAT_CHANSTS_COMPLETED_DESCRIPTOR_ADDR;
#else
        phys_complete =
                ioat_chan->completion_virt->low & IOAT_LOW_COMPLETION_MASK;
#endif

        if ((ioat_chan->completion_virt->full
                & IOAT_CHANSTS_DMA_TRANSFER_STATUS) ==
                                IOAT_CHANSTS_DMA_TRANSFER_STATUS_HALTED) {
                dev_err(&ioat_chan->device->pdev->dev,
                        "Channel halted, chanerr = %x\n",
                        readl(ioat_chan->reg_base + IOAT_CHANERR_OFFSET));

                /* TODO do something to salvage the situation */
        }

        if (phys_complete == ioat_chan->last_completion) {
                spin_unlock_bh(&ioat_chan->cleanup_lock);
                return;
        }

        cookie = 0;
        spin_lock_bh(&ioat_chan->desc_lock);
        switch (ioat_chan->device->version) {
        case IOAT_VER_1_2:
                list_for_each_entry_safe(desc, _desc,
                                         &ioat_chan->used_desc, node) {

                        /*
                         * Incoming DMA requests may use multiple descriptors,
                         * due to exceeding xfercap, perhaps. If so, only the
                         * last one will have a cookie, and require unmapping.
                         */
                        if (desc->async_tx.cookie) {
                                cookie = desc->async_tx.cookie;

                                /*
                                 * yes we are unmapping both _page and _single
                                 * alloc'd regions with unmap_page. Is this
                                 * *really* that bad?
                                 */
                                pci_unmap_page(ioat_chan->device->pdev,
                                                pci_unmap_addr(desc, dst),
                                                pci_unmap_len(desc, len),
                                                PCI_DMA_FROMDEVICE);
                                pci_unmap_page(ioat_chan->device->pdev,
                                                pci_unmap_addr(desc, src),
                                                pci_unmap_len(desc, len),
                                                PCI_DMA_TODEVICE);

                                if (desc->async_tx.callback) {
                                        desc->async_tx.callback(desc->async_tx.callback_param);
                                        desc->async_tx.callback = NULL;
                                }
                        }

                        if (desc->async_tx.phys != phys_complete) {
                                /*
                                 * a completed entry, but not the last, so clean
                                 * up if the client is done with the descriptor
                                 */
                                if (desc->async_tx.ack) {
                                        list_del(&desc->node);
                                        list_add_tail(&desc->node,
                                                      &ioat_chan->free_desc);
                                } else
                                        desc->async_tx.cookie = 0;
                        } else {
                                /*
                                 * last used desc. Do not remove, so we can
                                 * append from it, but don't look at it next
                                 * time, either
                                 */
                                desc->async_tx.cookie = 0;

                                /* TODO check status bits? */
                                break;
                        }
                }
                break;
        case IOAT_VER_2_0:
                /* has some other thread has already cleaned up? */
                if (ioat_chan->used_desc.prev == NULL)
                        break;

                /* work backwards to find latest finished desc */
                desc = to_ioat_desc(ioat_chan->used_desc.next);
                latest_desc = NULL;
                do {
                        desc = to_ioat_desc(desc->node.prev);
                        desc_phys = (unsigned long)desc->async_tx.phys
                                       & IOAT_CHANSTS_COMPLETED_DESCRIPTOR_ADDR;
                        if (desc_phys == phys_complete) {
                                latest_desc = desc;
                                break;
                        }
                } while (&desc->node != ioat_chan->used_desc.prev);

                if (latest_desc != NULL) {

                        /* work forwards to clear finished descriptors */
                        for (desc = to_ioat_desc(ioat_chan->used_desc.prev);
                             &desc->node != latest_desc->node.next &&
                             &desc->node != ioat_chan->used_desc.next;
                             desc = to_ioat_desc(desc->node.next)) {
                                if (desc->async_tx.cookie) {
                                        cookie = desc->async_tx.cookie;
                                        desc->async_tx.cookie = 0;

                                        pci_unmap_page(ioat_chan->device->pdev,
                                                      pci_unmap_addr(desc, dst),
                                                      pci_unmap_len(desc, len),
                                                      PCI_DMA_FROMDEVICE);
                                        pci_unmap_page(ioat_chan->device->pdev,
                                                      pci_unmap_addr(desc, src),
                                                      pci_unmap_len(desc, len),
                                                      PCI_DMA_TODEVICE);

                                        if (desc->async_tx.callback) {
                                                desc->async_tx.callback(desc->async_tx.callback_param);
                                                desc->async_tx.callback = NULL;
                                        }
                                }
                        }

                        /* move used.prev up beyond those that are finished */
                        if (&desc->node == ioat_chan->used_desc.next)
                                ioat_chan->used_desc.prev = NULL;
                        else
                                ioat_chan->used_desc.prev = &desc->node;
                }
                break;
        }

        spin_unlock_bh(&ioat_chan->desc_lock);

        ioat_chan->last_completion = phys_complete;
        if (cookie != 0)
                ioat_chan->completed_cookie = cookie;

        spin_unlock_bh(&ioat_chan->cleanup_lock);
}

static void ioat_dma_dependency_added(struct dma_chan *chan)
{
        struct ioat_dma_chan *ioat_chan = to_ioat_chan(chan);
        spin_lock_bh(&ioat_chan->desc_lock);
        if (ioat_chan->pending == 0) {
                spin_unlock_bh(&ioat_chan->desc_lock);
                ioat_dma_memcpy_cleanup(ioat_chan);
        } else
                spin_unlock_bh(&ioat_chan->desc_lock);
}

/**
 * ioat_dma_is_complete - poll the status of a IOAT DMA transaction
 * @chan: IOAT DMA channel handle
 * @cookie: DMA transaction identifier
 * @done: if not %NULL, updated with last completed transaction
 * @used: if not %NULL, updated with last used transaction
 */
static enum dma_status ioat_dma_is_complete(struct dma_chan *chan,
                                            dma_cookie_t cookie,
                                            dma_cookie_t *done,
                                            dma_cookie_t *used)
{
        struct ioat_dma_chan *ioat_chan = to_ioat_chan(chan);
        dma_cookie_t last_used;
        dma_cookie_t last_complete;
        enum dma_status ret;

        last_used = chan->cookie;
        last_complete = ioat_chan->completed_cookie;

        if (done)
                *done = last_complete;
        if (used)
                *used = last_used;

        ret = dma_async_is_complete(cookie, last_complete, last_used);
        if (ret == DMA_SUCCESS)
                return ret;

        ioat_dma_memcpy_cleanup(ioat_chan);

        last_used = chan->cookie;
        last_complete = ioat_chan->completed_cookie;

        if (done)
                *done = last_complete;
        if (used)
                *used = last_used;

        return dma_async_is_complete(cookie, last_complete, last_used);
}

static void ioat_dma_start_null_desc(struct ioat_dma_chan *ioat_chan)
{
        struct ioat_desc_sw *desc;

        spin_lock_bh(&ioat_chan->desc_lock);

        desc = ioat_dma_get_next_descriptor(ioat_chan);
        desc->hw->ctl = IOAT_DMA_DESCRIPTOR_NUL
                                | IOAT_DMA_DESCRIPTOR_CTL_INT_GN
                                | IOAT_DMA_DESCRIPTOR_CTL_CP_STS;
        desc->hw->size = 0;
        desc->hw->src_addr = 0;
        desc->hw->dst_addr = 0;
        desc->async_tx.ack = 1;
        switch (ioat_chan->device->version) {

        case IOAT_VER_1_2:
                desc->hw->next = 0;
                list_add_tail(&desc->node, &ioat_chan->used_desc);

                writel(((u64) desc->async_tx.phys) & 0x00000000FFFFFFFF,
                       ioat_chan->reg_base + IOAT1_CHAINADDR_OFFSET_LOW);
                writel(((u64) desc->async_tx.phys) >> 32,
                       ioat_chan->reg_base + IOAT1_CHAINADDR_OFFSET_HIGH);

                writeb(IOAT_CHANCMD_START, ioat_chan->reg_base
                        + IOAT_CHANCMD_OFFSET(ioat_chan->device->version));
                break;
        case IOAT_VER_2_0:
                writel(((u64) desc->async_tx.phys) & 0x00000000FFFFFFFF,
                       ioat_chan->reg_base + IOAT2_CHAINADDR_OFFSET_LOW);
                writel(((u64) desc->async_tx.phys) >> 32,
                       ioat_chan->reg_base + IOAT2_CHAINADDR_OFFSET_HIGH);

                ioat_chan->dmacount++;
                __ioat2_dma_memcpy_issue_pending(ioat_chan);
                break;
        }
        spin_unlock_bh(&ioat_chan->desc_lock);
}

/*
 * Perform a IOAT transaction to verify the HW works.
 */
#define IOAT_TEST_SIZE 2000

static void ioat_dma_test_callback(void *dma_async_param)
{
        printk(KERN_ERR "ioatdma: ioat_dma_test_callback(%p)\n",
                dma_async_param);
}

/**
 * ioat_dma_self_test - Perform a IOAT transaction to verify the HW works.
 * @device: device to be tested
 */
static int ioat_dma_self_test(struct ioatdma_device *device)
{
        int i;
        u8 *src;
        u8 *dest;
        struct dma_chan *dma_chan;
        struct dma_async_tx_descriptor *tx;
        dma_addr_t addr;
        dma_cookie_t cookie;
        int err = 0;

        src = kzalloc(sizeof(u8) * IOAT_TEST_SIZE, GFP_KERNEL);
        if (!src)
                return -ENOMEM;
        dest = kzalloc(sizeof(u8) * IOAT_TEST_SIZE, GFP_KERNEL);
        if (!dest) {
                kfree(src);
                return -ENOMEM;
        }

        /* Fill in src buffer */
        for (i = 0; i < IOAT_TEST_SIZE; i++)
                src[i] = (u8)i;

        /* Start copy, using first DMA channel */
        dma_chan = container_of(device->common.channels.next,
                                struct dma_chan,
                                device_node);
        if (device->common.device_alloc_chan_resources(dma_chan) < 1) {
                dev_err(&device->pdev->dev,
                        "selftest cannot allocate chan resource\n");
                err = -ENODEV;
                goto out;
        }

        tx = device->common.device_prep_dma_memcpy(dma_chan, IOAT_TEST_SIZE, 0);
        if (!tx) {
                dev_err(&device->pdev->dev,
                        "Self-test prep failed, disabling\n");
                err = -ENODEV;
                goto free_resources;
        }

        async_tx_ack(tx);
        addr = dma_map_single(dma_chan->device->dev, src, IOAT_TEST_SIZE,
                              DMA_TO_DEVICE);
        tx->tx_set_src(addr, tx, 0);
        addr = dma_map_single(dma_chan->device->dev, dest, IOAT_TEST_SIZE,
                              DMA_FROM_DEVICE);
        tx->tx_set_dest(addr, tx, 0);
        tx->callback = ioat_dma_test_callback;
        tx->callback_param = (void *)0x8086;
        cookie = tx->tx_submit(tx);
        if (cookie < 0) {
                dev_err(&device->pdev->dev,
                        "Self-test setup failed, disabling\n");
                err = -ENODEV;
                goto free_resources;
        }
        device->common.device_issue_pending(dma_chan);
        msleep(1);

        if (device->common.device_is_tx_complete(dma_chan, cookie, NULL, NULL)
                                        != DMA_SUCCESS) {
                dev_err(&device->pdev->dev,
                        "Self-test copy timed out, disabling\n");
                err = -ENODEV;
                goto free_resources;
        }
        if (memcmp(src, dest, IOAT_TEST_SIZE)) {
                dev_err(&device->pdev->dev,
                        "Self-test copy failed compare, disabling\n");
                err = -ENODEV;
                goto free_resources;
        }

free_resources:
        device->common.device_free_chan_resources(dma_chan);
out:
        kfree(src);
        kfree(dest);
        return err;
}

static char ioat_interrupt_style[32] = "msix";
module_param_string(ioat_interrupt_style, ioat_interrupt_style,
                    sizeof(ioat_interrupt_style), 0644);
MODULE_PARM_DESC(ioat_interrupt_style,
                 "set ioat interrupt style: msix (default), "
                 "msix-single-vector, msi, intx)");

/**
 * ioat_dma_setup_interrupts - setup interrupt handler
 * @device: ioat device
 */
static int ioat_dma_setup_interrupts(struct ioatdma_device *device)
{
        struct ioat_dma_chan *ioat_chan;
        int err, i, j, msixcnt;
        u8 intrctrl = 0;

        if (!strcmp(ioat_interrupt_style, "msix"))
                goto msix;
        if (!strcmp(ioat_interrupt_style, "msix-single-vector"))
                goto msix_single_vector;
        if (!strcmp(ioat_interrupt_style, "msi"))
                goto msi;
        if (!strcmp(ioat_interrupt_style, "intx"))
                goto intx;
        dev_err(&device->pdev->dev, "invalid ioat_interrupt_style %s\n",
                ioat_interrupt_style);
        goto err_no_irq;

msix:
        /* The number of MSI-X vectors should equal the number of channels */
        msixcnt = device->common.chancnt;
        for (i = 0; i < msixcnt; i++)
                device->msix_entries[i].entry = i;

        err = pci_enable_msix(device->pdev, device->msix_entries, msixcnt);
        if (err < 0)
                goto msi;
        if (err > 0)
                goto msix_single_vector;

        for (i = 0; i < msixcnt; i++) {
                ioat_chan = ioat_lookup_chan_by_index(device, i);
                err = request_irq(device->msix_entries[i].vector,
                                  ioat_dma_do_interrupt_msix,
                                  0, "ioat-msix", ioat_chan);
                if (err) {
                        for (j = 0; j < i; j++) {
                                ioat_chan =
                                        ioat_lookup_chan_by_index(device, j);
                                free_irq(device->msix_entries[j].vector,
                                         ioat_chan);
                        }
                        goto msix_single_vector;
                }
        }
        intrctrl |= IOAT_INTRCTRL_MSIX_VECTOR_CONTROL;
        device->irq_mode = msix_multi_vector;
        goto done;

msix_single_vector:
        device->msix_entries[0].entry = 0;
        err = pci_enable_msix(device->pdev, device->msix_entries, 1);
        if (err)
                goto msi;

        err = request_irq(device->msix_entries[0].vector, ioat_dma_do_interrupt,
                          0, "ioat-msix", device);
        if (err) {
                pci_disable_msix(device->pdev);
                goto msi;
        }
        device->irq_mode = msix_single_vector;
        goto done;

msi:
        err = pci_enable_msi(device->pdev);
        if (err)
                goto intx;

        err = request_irq(device->pdev->irq, ioat_dma_do_interrupt,
                          0, "ioat-msi", device);
        if (err) {
                pci_disable_msi(device->pdev);
                goto intx;
        }
        /*
         * CB 1.2 devices need a bit set in configuration space to enable MSI
         */
        if (device->version == IOAT_VER_1_2) {
                u32 dmactrl;
                pci_read_config_dword(device->pdev,
                                      IOAT_PCI_DMACTRL_OFFSET, &dmactrl);
                dmactrl |= IOAT_PCI_DMACTRL_MSI_EN;
                pci_write_config_dword(device->pdev,
                                       IOAT_PCI_DMACTRL_OFFSET, dmactrl);
        }
        device->irq_mode = msi;
        goto done;

intx:
        err = request_irq(device->pdev->irq, ioat_dma_do_interrupt,
                          IRQF_SHARED, "ioat-intx", device);
        if (err)
                goto err_no_irq;
        device->irq_mode = intx;

done:
        intrctrl |= IOAT_INTRCTRL_MASTER_INT_EN;
        writeb(intrctrl, device->reg_base + IOAT_INTRCTRL_OFFSET);
        return 0;

err_no_irq:
        /* Disable all interrupt generation */
        writeb(0, device->reg_base + IOAT_INTRCTRL_OFFSET);
        dev_err(&device->pdev->dev, "no usable interrupts\n");
        device->irq_mode = none;
        return -1;
}

/**
 * ioat_dma_remove_interrupts - remove whatever interrupts were set
 * @device: ioat device
 */
static void ioat_dma_remove_interrupts(struct ioatdma_device *device)
{
        struct ioat_dma_chan *ioat_chan;
        int i;

        /* Disable all interrupt generation */
        writeb(0, device->reg_base + IOAT_INTRCTRL_OFFSET);

        switch (device->irq_mode) {
        case msix_multi_vector:
                for (i = 0; i < device->common.chancnt; i++) {
                        ioat_chan = ioat_lookup_chan_by_index(device, i);
                        free_irq(device->msix_entries[i].vector, ioat_chan);
                }
                pci_disable_msix(device->pdev);
                break;
        case msix_single_vector:
                free_irq(device->msix_entries[0].vector, device);
                pci_disable_msix(device->pdev);
                break;
        case msi:
                free_irq(device->pdev->irq, device);
                pci_disable_msi(device->pdev);
                break;
        case intx:
                free_irq(device->pdev->irq, device);
                break;
        case none:
                dev_warn(&device->pdev->dev,
                         "call to %s without interrupts setup\n", __func__);
        }
        device->irq_mode = none;
}

struct ioatdma_device *ioat_dma_probe(struct pci_dev *pdev,
                                      void __iomem *iobase)
{
        int err;
        struct ioatdma_device *device;

        device = kzalloc(sizeof(*device), GFP_KERNEL);
        if (!device) {
                err = -ENOMEM;
                goto err_kzalloc;
        }
        device->pdev = pdev;
        device->reg_base = iobase;
        device->version = readb(device->reg_base + IOAT_VER_OFFSET);

        /* DMA coherent memory pool for DMA descriptor allocations */
        device->dma_pool = pci_pool_create("dma_desc_pool", pdev,
                                           sizeof(struct ioat_dma_descriptor),
                                           64, 0);
        if (!device->dma_pool) {
                err = -ENOMEM;
                goto err_dma_pool;
        }

        device->completion_pool = pci_pool_create("completion_pool", pdev,
                                                  sizeof(u64), SMP_CACHE_BYTES,
                                                  SMP_CACHE_BYTES);
        if (!device->completion_pool) {
                err = -ENOMEM;
                goto err_completion_pool;
        }

        INIT_LIST_HEAD(&device->common.channels);
        ioat_dma_enumerate_channels(device);

        device->common.device_alloc_chan_resources =
                                                ioat_dma_alloc_chan_resources;
        device->common.device_free_chan_resources =
                                                ioat_dma_free_chan_resources;
        device->common.dev = &pdev->dev;

        dma_cap_set(DMA_MEMCPY, device->common.cap_mask);
        device->common.device_is_tx_complete = ioat_dma_is_complete;
        device->common.device_dependency_added = ioat_dma_dependency_added;
        switch (device->version) {
        case IOAT_VER_1_2:
                device->common.device_prep_dma_memcpy = ioat1_dma_prep_memcpy;
                device->common.device_issue_pending =
                                                ioat1_dma_memcpy_issue_pending;
                break;
        case IOAT_VER_2_0:
                device->common.device_prep_dma_memcpy = ioat2_dma_prep_memcpy;
                device->common.device_issue_pending =
                                                ioat2_dma_memcpy_issue_pending;
                break;
        }

        dev_err(&device->pdev->dev,
                "Intel(R) I/OAT DMA Engine found,"
                " %d channels, device version 0x%02x, driver version %s\n",
                device->common.chancnt, device->version, IOAT_DMA_VERSION);

        err = ioat_dma_setup_interrupts(device);
        if (err)
                goto err_setup_interrupts;

        err = ioat_dma_self_test(device);
        if (err)
                goto err_self_test;

        dma_async_device_register(&device->common);

        return device;

err_self_test:
        ioat_dma_remove_interrupts(device);
err_setup_interrupts:
        pci_pool_destroy(device->completion_pool);
err_completion_pool:
        pci_pool_destroy(device->dma_pool);
err_dma_pool:
        kfree(device);
err_kzalloc:
        dev_err(&pdev->dev,
                "Intel(R) I/OAT DMA Engine initialization failed\n");
        return NULL;
}

void ioat_dma_remove(struct ioatdma_device *device)
{
        struct dma_chan *chan, *_chan;
        struct ioat_dma_chan *ioat_chan;

        ioat_dma_remove_interrupts(device);

        dma_async_device_unregister(&device->common);

        pci_pool_destroy(device->dma_pool);
        pci_pool_destroy(device->completion_pool);

        iounmap(device->reg_base);
        pci_release_regions(device->pdev);
        pci_disable_device(device->pdev);

        list_for_each_entry_safe(chan, _chan,
                                 &device->common.channels, device_node) {
                ioat_chan = to_ioat_chan(chan);
                list_del(&chan->device_node);
                kfree(ioat_chan);
        }
        kfree(device);
}