/*
 * Intel MIC Platform Software Stack (MPSS)
 *
 * Copyright(c) 2015 Intel Corporation.
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms 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.
 *
 * Intel SCIF driver.
 *
 */
#include "scif_main.h"
#include "scif_map.h"

/*
 * struct scif_dma_comp_cb - SCIF DMA completion callback
 *
 * @dma_completion_func: DMA completion callback
 * @cb_cookie: DMA completion callback cookie
 * @temp_buf: Temporary buffer
 * @temp_buf_to_free: Temporary buffer to be freed
 * @is_cache: Is a kmem_cache allocated buffer
 * @dst_offset: Destination registration offset
 * @dst_window: Destination registration window
 * @len: Length of the temp buffer
 * @temp_phys: DMA address of the temp buffer
 * @sdev: The SCIF device
 * @header_padding: padding for cache line alignment
 */
struct scif_dma_comp_cb {
        void (*dma_completion_func)(void *cookie);
        void *cb_cookie;
        u8 *temp_buf;
        u8 *temp_buf_to_free;
        bool is_cache;
        s64 dst_offset;
        struct scif_window *dst_window;
        size_t len;
        dma_addr_t temp_phys;
        struct scif_dev *sdev;
        int header_padding;
};

/**
 * struct scif_copy_work - Work for DMA copy
 *
 * @src_offset: Starting source offset
 * @dst_offset: Starting destination offset
 * @src_window: Starting src registered window
 * @dst_window: Starting dst registered window
 * @loopback: true if this is a loopback DMA transfer
 * @len: Length of the transfer
 * @comp_cb: DMA copy completion callback
 * @remote_dev: The remote SCIF peer device
 * @fence_type: polling or interrupt based
 * @ordered: is this a tail byte ordered DMA transfer
 */
struct scif_copy_work {
        s64 src_offset;
        s64 dst_offset;
        struct scif_window *src_window;
        struct scif_window *dst_window;
        int loopback;
        size_t len;
        struct scif_dma_comp_cb   *comp_cb;
        struct scif_dev *remote_dev;
        int fence_type;
        bool ordered;
};

/**
 * scif_reserve_dma_chan:
 * @ep: Endpoint Descriptor.
 *
 * This routine reserves a DMA channel for a particular
 * endpoint. All DMA transfers for an endpoint are always
 * programmed on the same DMA channel.
 */
int scif_reserve_dma_chan(struct scif_endpt *ep)
{
        int err = 0;
        struct scif_dev *scifdev;
        struct scif_hw_dev *sdev;
        struct dma_chan *chan;

        /* Loopback DMAs are not supported on the management node */
        if (!scif_info.nodeid && scifdev_self(ep->remote_dev))
                return 0;
        if (scif_info.nodeid)
                scifdev = &scif_dev[0];
        else
                scifdev = ep->remote_dev;
        sdev = scifdev->sdev;
        if (!sdev->num_dma_ch)
                return -ENODEV;
        chan = sdev->dma_ch[scifdev->dma_ch_idx];
        scifdev->dma_ch_idx = (scifdev->dma_ch_idx + 1) % sdev->num_dma_ch;
        mutex_lock(&ep->rma_info.rma_lock);
        ep->rma_info.dma_chan = chan;
        mutex_unlock(&ep->rma_info.rma_lock);
        return err;
}

#ifdef CONFIG_MMU_NOTIFIER
/**
 * scif_rma_destroy_tcw:
 *
 * This routine destroys temporary cached windows
 */
static
void __scif_rma_destroy_tcw(struct scif_mmu_notif *mmn,
                            u64 start, u64 len)
{
        struct list_head *item, *tmp;
        struct scif_window *window;
        u64 start_va, end_va;
        u64 end = start + len;

        if (end <= start)
                return;

        list_for_each_safe(item, tmp, &mmn->tc_reg_list) {
                window = list_entry(item, struct scif_window, list);
                if (!len)
                        break;
                start_va = window->va_for_temp;
                end_va = start_va + (window->nr_pages << PAGE_SHIFT);
                if (start < start_va && end <= start_va)
                        break;
                if (start >= end_va)
                        continue;
                __scif_rma_destroy_tcw_helper(window);
        }
}

static void scif_rma_destroy_tcw(struct scif_mmu_notif *mmn, u64 start, u64 len)
{
        struct scif_endpt *ep = mmn->ep;

        spin_lock(&ep->rma_info.tc_lock);
        __scif_rma_destroy_tcw(mmn, start, len);
        spin_unlock(&ep->rma_info.tc_lock);
}

static void scif_rma_destroy_tcw_ep(struct scif_endpt *ep)
{
        struct list_head *item, *tmp;
        struct scif_mmu_notif *mmn;

        list_for_each_safe(item, tmp, &ep->rma_info.mmn_list) {
                mmn = list_entry(item, struct scif_mmu_notif, list);
                scif_rma_destroy_tcw(mmn, 0, ULONG_MAX);
        }
}

static void __scif_rma_destroy_tcw_ep(struct scif_endpt *ep)
{
        struct list_head *item, *tmp;
        struct scif_mmu_notif *mmn;

        spin_lock(&ep->rma_info.tc_lock);
        list_for_each_safe(item, tmp, &ep->rma_info.mmn_list) {
                mmn = list_entry(item, struct scif_mmu_notif, list);
                __scif_rma_destroy_tcw(mmn, 0, ULONG_MAX);
        }
        spin_unlock(&ep->rma_info.tc_lock);
}

static bool scif_rma_tc_can_cache(struct scif_endpt *ep, size_t cur_bytes)
{
        if ((cur_bytes >> PAGE_SHIFT) > scif_info.rma_tc_limit)
                return false;
        if ((atomic_read(&ep->rma_info.tcw_total_pages)
                        + (cur_bytes >> PAGE_SHIFT)) >
                        scif_info.rma_tc_limit) {
                dev_info(scif_info.mdev.this_device,
                         "%s %d total=%d, current=%zu reached max\n",
                         __func__, __LINE__,
                         atomic_read(&ep->rma_info.tcw_total_pages),
                         (1 + (cur_bytes >> PAGE_SHIFT)));
                scif_rma_destroy_tcw_invalid();
                __scif_rma_destroy_tcw_ep(ep);
        }
        return true;
}

static void scif_mmu_notifier_release(struct mmu_notifier *mn,
                                      struct mm_struct *mm)
{
        struct scif_mmu_notif   *mmn;

        mmn = container_of(mn, struct scif_mmu_notif, ep_mmu_notifier);
        scif_rma_destroy_tcw(mmn, 0, ULONG_MAX);
        schedule_work(&scif_info.misc_work);
}

static void scif_mmu_notifier_invalidate_page(struct mmu_notifier *mn,
                                              struct mm_struct *mm,
                                              unsigned long address)
{
        struct scif_mmu_notif   *mmn;

        mmn = container_of(mn, struct scif_mmu_notif, ep_mmu_notifier);
        scif_rma_destroy_tcw(mmn, address, PAGE_SIZE);
}

static void scif_mmu_notifier_invalidate_range_start(struct mmu_notifier *mn,
                                                     struct mm_struct *mm,
                                                     unsigned long start,
                                                     unsigned long end)
{
        struct scif_mmu_notif   *mmn;

        mmn = container_of(mn, struct scif_mmu_notif, ep_mmu_notifier);
        scif_rma_destroy_tcw(mmn, start, end - start);
}

static void scif_mmu_notifier_invalidate_range_end(struct mmu_notifier *mn,
                                                   struct mm_struct *mm,
                                                   unsigned long start,
                                                   unsigned long end)
{
        /*
         * Nothing to do here, everything needed was done in
         * invalidate_range_start.
         */
}

static const struct mmu_notifier_ops scif_mmu_notifier_ops = {
        .release = scif_mmu_notifier_release,
        .clear_flush_young = NULL,
        .invalidate_page = scif_mmu_notifier_invalidate_page,
        .invalidate_range_start = scif_mmu_notifier_invalidate_range_start,
        .invalidate_range_end = scif_mmu_notifier_invalidate_range_end};

static void scif_ep_unregister_mmu_notifier(struct scif_endpt *ep)
{
        struct scif_endpt_rma_info *rma = &ep->rma_info;
        struct scif_mmu_notif *mmn = NULL;
        struct list_head *item, *tmp;

        mutex_lock(&ep->rma_info.mmn_lock);
        list_for_each_safe(item, tmp, &rma->mmn_list) {
                mmn = list_entry(item, struct scif_mmu_notif, list);
                mmu_notifier_unregister(&mmn->ep_mmu_notifier, mmn->mm);
                list_del(item);
                kfree(mmn);
        }
        mutex_unlock(&ep->rma_info.mmn_lock);
}

static void scif_init_mmu_notifier(struct scif_mmu_notif *mmn,
                                   struct mm_struct *mm, struct scif_endpt *ep)
{
        mmn->ep = ep;
        mmn->mm = mm;
        mmn->ep_mmu_notifier.ops = &scif_mmu_notifier_ops;
        INIT_LIST_HEAD(&mmn->list);
        INIT_LIST_HEAD(&mmn->tc_reg_list);
}

static struct scif_mmu_notif *
scif_find_mmu_notifier(struct mm_struct *mm, struct scif_endpt_rma_info *rma)
{
        struct scif_mmu_notif *mmn;

        list_for_each_entry(mmn, &rma->mmn_list, list)
                if (mmn->mm == mm)
                        return mmn;
        return NULL;
}

static struct scif_mmu_notif *
scif_add_mmu_notifier(struct mm_struct *mm, struct scif_endpt *ep)
{
        struct scif_mmu_notif *mmn
                 = kzalloc(sizeof(*mmn), GFP_KERNEL);

        if (!mmn)
                return ERR_PTR(-ENOMEM);

        scif_init_mmu_notifier(mmn, current->mm, ep);
        if (mmu_notifier_register(&mmn->ep_mmu_notifier, current->mm)) {
                kfree(mmn);
                return ERR_PTR(-EBUSY);
        }
        list_add(&mmn->list, &ep->rma_info.mmn_list);
        return mmn;
}

/*
 * Called from the misc thread to destroy temporary cached windows and
 * unregister the MMU notifier for the SCIF endpoint.
 */
void scif_mmu_notif_handler(struct work_struct *work)
{
        struct list_head *pos, *tmpq;
        struct scif_endpt *ep;
restart:
        scif_rma_destroy_tcw_invalid();
        spin_lock(&scif_info.rmalock);
        list_for_each_safe(pos, tmpq, &scif_info.mmu_notif_cleanup) {
                ep = list_entry(pos, struct scif_endpt, mmu_list);
                list_del(&ep->mmu_list);
                spin_unlock(&scif_info.rmalock);
                scif_rma_destroy_tcw_ep(ep);
                scif_ep_unregister_mmu_notifier(ep);
                goto restart;
        }
        spin_unlock(&scif_info.rmalock);
}

static bool scif_is_set_reg_cache(int flags)
{
        return !!(flags & SCIF_RMA_USECACHE);
}
#else
static struct scif_mmu_notif *
scif_find_mmu_notifier(struct mm_struct *mm,
                       struct scif_endpt_rma_info *rma)
{
        return NULL;
}

static struct scif_mmu_notif *
scif_add_mmu_notifier(struct mm_struct *mm, struct scif_endpt *ep)
{
        return NULL;
}

void scif_mmu_notif_handler(struct work_struct *work)
{
}

static bool scif_is_set_reg_cache(int flags)
{
        return false;
}

static bool scif_rma_tc_can_cache(struct scif_endpt *ep, size_t cur_bytes)
{
        return false;
}
#endif

/**
 * scif_register_temp:
 * @epd: End Point Descriptor.
 * @addr: virtual address to/from which to copy
 * @len: length of range to copy
 * @out_offset: computed offset returned by reference.
 * @out_window: allocated registered window returned by reference.
 *
 * Create a temporary registered window. The peer will not know about this
 * window. This API is used for scif_vreadfrom()/scif_vwriteto() API's.
 */
static int
scif_register_temp(scif_epd_t epd, unsigned long addr, size_t len, int prot,
                   off_t *out_offset, struct scif_window **out_window)
{
        struct scif_endpt *ep = (struct scif_endpt *)epd;
        int err;
        scif_pinned_pages_t pinned_pages;
        size_t aligned_len;

        aligned_len = ALIGN(len, PAGE_SIZE);

        err = __scif_pin_pages((void *)(addr & PAGE_MASK),
                               aligned_len, &prot, 0, &pinned_pages);
        if (err)
                return err;

        pinned_pages->prot = prot;

        /* Compute the offset for this registration */
        err = scif_get_window_offset(ep, 0, 0,
                                     aligned_len >> PAGE_SHIFT,
                                     (s64 *)out_offset);
        if (err)
                goto error_unpin;

        /* Allocate and prepare self registration window */
        *out_window = scif_create_window(ep, aligned_len >> PAGE_SHIFT,
                                        *out_offset, true);
        if (!*out_window) {
                scif_free_window_offset(ep, NULL, *out_offset);
                err = -ENOMEM;
                goto error_unpin;
        }

        (*out_window)->pinned_pages = pinned_pages;
        (*out_window)->nr_pages = pinned_pages->nr_pages;
        (*out_window)->prot = pinned_pages->prot;

        (*out_window)->va_for_temp = addr & PAGE_MASK;
        err = scif_map_window(ep->remote_dev, *out_window);
        if (err) {
                /* Something went wrong! Rollback */
                scif_destroy_window(ep, *out_window);
                *out_window = NULL;
        } else {
                *out_offset |= (addr - (*out_window)->va_for_temp);
        }
        return err;
error_unpin:
        if (err)
                dev_err(&ep->remote_dev->sdev->dev,
                        "%s %d err %d\n", __func__, __LINE__, err);
        scif_unpin_pages(pinned_pages);
        return err;
}

#define SCIF_DMA_TO (3 * HZ)

/*
 * scif_sync_dma - Program a DMA without an interrupt descriptor
 *
 * @dev - The address of the pointer to the device instance used
 * for DMA registration.
 * @chan - DMA channel to be used.
 * @sync_wait: Wait for DMA to complete?
 *
 * Return 0 on success and -errno on error.
 */
static int scif_sync_dma(struct scif_hw_dev *sdev, struct dma_chan *chan,
                         bool sync_wait)
{
        int err = 0;
        struct dma_async_tx_descriptor *tx = NULL;
        enum dma_ctrl_flags flags = DMA_PREP_FENCE;
        dma_cookie_t cookie;
        struct dma_device *ddev;

        if (!chan) {
                err = -EIO;
                dev_err(&sdev->dev, "%s %d err %d\n",
                        __func__, __LINE__, err);
                return err;
        }
        ddev = chan->device;

        tx = ddev->device_prep_dma_memcpy(chan, 0, 0, 0, flags);
        if (!tx) {
                err = -ENOMEM;
                dev_err(&sdev->dev, "%s %d err %d\n",
                        __func__, __LINE__, err);
                goto release;
        }
        cookie = tx->tx_submit(tx);

        if (dma_submit_error(cookie)) {
                err = -ENOMEM;
                dev_err(&sdev->dev, "%s %d err %d\n",
                        __func__, __LINE__, err);
                goto release;
        }
        if (!sync_wait) {
                dma_async_issue_pending(chan);
        } else {
                if (dma_sync_wait(chan, cookie) == DMA_COMPLETE) {
                        err = 0;
                } else {
                        err = -EIO;
                        dev_err(&sdev->dev, "%s %d err %d\n",
                                __func__, __LINE__, err);
                }
        }
release:
        return err;
}

static void scif_dma_callback(void *arg)
{
        struct completion *done = (struct completion *)arg;

        complete(done);
}

#define SCIF_DMA_SYNC_WAIT true
#define SCIF_DMA_POLL BIT(0)
#define SCIF_DMA_INTR BIT(1)

/*
 * scif_async_dma - Program a DMA with an interrupt descriptor
 *
 * @dev - The address of the pointer to the device instance used
 * for DMA registration.
 * @chan - DMA channel to be used.
 * Return 0 on success and -errno on error.
 */
static int scif_async_dma(struct scif_hw_dev *sdev, struct dma_chan *chan)
{
        int err = 0;
        struct dma_device *ddev;
        struct dma_async_tx_descriptor *tx = NULL;
        enum dma_ctrl_flags flags = DMA_PREP_INTERRUPT | DMA_PREP_FENCE;
        DECLARE_COMPLETION_ONSTACK(done_wait);
        dma_cookie_t cookie;
        enum dma_status status;

        if (!chan) {
                err = -EIO;
                dev_err(&sdev->dev, "%s %d err %d\n",
                        __func__, __LINE__, err);
                return err;
        }
        ddev = chan->device;

        tx = ddev->device_prep_dma_memcpy(chan, 0, 0, 0, flags);
        if (!tx) {
                err = -ENOMEM;
                dev_err(&sdev->dev, "%s %d err %d\n",
                        __func__, __LINE__, err);
                goto release;
        }
        reinit_completion(&done_wait);
        tx->callback = scif_dma_callback;
        tx->callback_param = &done_wait;
        cookie = tx->tx_submit(tx);

        if (dma_submit_error(cookie)) {
                err = -ENOMEM;
                dev_err(&sdev->dev, "%s %d err %d\n",
                        __func__, __LINE__, err);
                goto release;
        }
        dma_async_issue_pending(chan);

        err = wait_for_completion_timeout(&done_wait, SCIF_DMA_TO);
        if (!err) {
                err = -EIO;
                dev_err(&sdev->dev, "%s %d err %d\n",
                        __func__, __LINE__, err);
                goto release;
        }
        err = 0;
        status = dma_async_is_tx_complete(chan, cookie, NULL, NULL);
        if (status != DMA_COMPLETE) {
                err = -EIO;
                dev_err(&sdev->dev, "%s %d err %d\n",
                        __func__, __LINE__, err);
                goto release;
        }
release:
        return err;
}

/*
 * scif_drain_dma_poll - Drain all outstanding DMA operations for a particular
 * DMA channel via polling.
 *
 * @sdev - The SCIF device
 * @chan - DMA channel
 * Return 0 on success and -errno on error.
 */
static int scif_drain_dma_poll(struct scif_hw_dev *sdev, struct dma_chan *chan)
{
        if (!chan)
                return -EINVAL;
        return scif_sync_dma(sdev, chan, SCIF_DMA_SYNC_WAIT);
}

/*
 * scif_drain_dma_intr - Drain all outstanding DMA operations for a particular
 * DMA channel via interrupt based blocking wait.
 *
 * @sdev - The SCIF device
 * @chan - DMA channel
 * Return 0 on success and -errno on error.
 */
int scif_drain_dma_intr(struct scif_hw_dev *sdev, struct dma_chan *chan)
{
        if (!chan)
                return -EINVAL;
        return scif_async_dma(sdev, chan);
}

/**
 * scif_rma_destroy_windows:
 *
 * This routine destroys all windows queued for cleanup
 */
void scif_rma_destroy_windows(void)
{
        struct list_head *item, *tmp;
        struct scif_window *window;
        struct scif_endpt *ep;
        struct dma_chan *chan;

        might_sleep();
restart:
        spin_lock(&scif_info.rmalock);
        list_for_each_safe(item, tmp, &scif_info.rma) {
                window = list_entry(item, struct scif_window,
                                    list);
                ep = (struct scif_endpt *)window->ep;
                chan = ep->rma_info.dma_chan;

                list_del_init(&window->list);
                spin_unlock(&scif_info.rmalock);
                if (!chan || !scifdev_alive(ep) ||
                    !scif_drain_dma_intr(ep->remote_dev->sdev,
                                         ep->rma_info.dma_chan))
                        /* Remove window from global list */
                        window->unreg_state = OP_COMPLETED;
                else
                        dev_warn(&ep->remote_dev->sdev->dev,
                                 "DMA engine hung?\n");
                if (window->unreg_state == OP_COMPLETED) {
                        if (window->type == SCIF_WINDOW_SELF)
                                scif_destroy_window(ep, window);
                        else
                                scif_destroy_remote_window(window);
                        atomic_dec(&ep->rma_info.tw_refcount);
                }
                goto restart;
        }
        spin_unlock(&scif_info.rmalock);
}

/**
 * scif_rma_destroy_tcw:
 *
 * This routine destroys temporary cached registered windows
 * which have been queued for cleanup.
 */
void scif_rma_destroy_tcw_invalid(void)
{
        struct list_head *item, *tmp;
        struct scif_window *window;
        struct scif_endpt *ep;
        struct dma_chan *chan;

        might_sleep();
restart:
        spin_lock(&scif_info.rmalock);
        list_for_each_safe(item, tmp, &scif_info.rma_tc) {
                window = list_entry(item, struct scif_window, list);
                ep = (struct scif_endpt *)window->ep;
                chan = ep->rma_info.dma_chan;
                list_del_init(&window->list);
                spin_unlock(&scif_info.rmalock);
                mutex_lock(&ep->rma_info.rma_lock);
                if (!chan || !scifdev_alive(ep) ||
                    !scif_drain_dma_intr(ep->remote_dev->sdev,
                                         ep->rma_info.dma_chan)) {
                        atomic_sub(window->nr_pages,
                                   &ep->rma_info.tcw_total_pages);
                        scif_destroy_window(ep, window);
                        atomic_dec(&ep->rma_info.tcw_refcount);
                } else {
                        dev_warn(&ep->remote_dev->sdev->dev,
                                 "DMA engine hung?\n");
                }
                mutex_unlock(&ep->rma_info.rma_lock);
                goto restart;
        }
        spin_unlock(&scif_info.rmalock);
}

static inline
void *_get_local_va(off_t off, struct scif_window *window, size_t len)
{
        int page_nr = (off - window->offset) >> PAGE_SHIFT;
        off_t page_off = off & ~PAGE_MASK;
        void *va = NULL;

        if (window->type == SCIF_WINDOW_SELF) {
                struct page **pages = window->pinned_pages->pages;

                va = page_address(pages[page_nr]) + page_off;
        }
        return va;
}

static inline
void *ioremap_remote(off_t off, struct scif_window *window,
                     size_t len, struct scif_dev *dev,
                     struct scif_window_iter *iter)
{
        dma_addr_t phys = scif_off_to_dma_addr(window, off, NULL, iter);

        /*
         * If the DMA address is not card relative then we need the DMA
         * addresses to be an offset into the bar. The aperture base was already
         * added so subtract it here since scif_ioremap is going to add it again
         */
        if (!scifdev_self(dev) && window->type == SCIF_WINDOW_PEER &&
            dev->sdev->aper && !dev->sdev->card_rel_da)
                phys = phys - dev->sdev->aper->pa;
        return scif_ioremap(phys, len, dev);
}

static inline void
iounmap_remote(void *virt, size_t size, struct scif_copy_work *work)
{
        scif_iounmap(virt, size, work->remote_dev);
}

/*
 * Takes care of ordering issue caused by
 * 1. Hardware:  Only in the case of cpu copy from mgmt node to card
 * because of WC memory.
 * 2. Software: If memcpy reorders copy instructions for optimization.
 * This could happen at both mgmt node and card.
 */
static inline void
scif_ordered_memcpy_toio(char *dst, const char *src, size_t count)
{
        if (!count)
                return;

        memcpy_toio((void __iomem __force *)dst, src, --count);
        /* Order the last byte with the previous stores */
        wmb();
        *(dst + count) = *(src + count);
}

static inline void scif_unaligned_cpy_toio(char *dst, const char *src,
                                           size_t count, bool ordered)
{
        if (ordered)
                scif_ordered_memcpy_toio(dst, src, count);
        else
                memcpy_toio((void __iomem __force *)dst, src, count);
}

static inline
void scif_ordered_memcpy_fromio(char *dst, const char *src, size_t count)
{
        if (!count)
                return;

        memcpy_fromio(dst, (void __iomem __force *)src, --count);
        /* Order the last byte with the previous loads */
        rmb();
        *(dst + count) = *(src + count);
}

static inline void scif_unaligned_cpy_fromio(char *dst, const char *src,
                                             size_t count, bool ordered)
{
        if (ordered)
                scif_ordered_memcpy_fromio(dst, src, count);
        else
                memcpy_fromio(dst, (void __iomem __force *)src, count);
}

#define SCIF_RMA_ERROR_CODE (~(dma_addr_t)0x0)

/*
 * scif_off_to_dma_addr:
 * Obtain the dma_addr given the window and the offset.
 * @window: Registered window.
 * @off: Window offset.
 * @nr_bytes: Return the number of contiguous bytes till next DMA addr index.
 * @index: Return the index of the dma_addr array found.
 * @start_off: start offset of index of the dma addr array found.
 * The nr_bytes provides the callee an estimate of the maximum possible
 * DMA xfer possible while the index/start_off provide faster lookups
 * for the next iteration.
 */
dma_addr_t scif_off_to_dma_addr(struct scif_window *window, s64 off,
                                size_t *nr_bytes, struct scif_window_iter *iter)
{
        int i, page_nr;
        s64 start, end;
        off_t page_off;

        if (window->nr_pages == window->nr_contig_chunks) {
                page_nr = (off - window->offset) >> PAGE_SHIFT;
                page_off = off & ~PAGE_MASK;

                if (nr_bytes)
                        *nr_bytes = PAGE_SIZE - page_off;
                return window->dma_addr[page_nr] | page_off;
        }
        if (iter) {
                i = iter->index;
                start = iter->offset;
        } else {
                i =  0;
                start =  window->offset;
        }
        for (; i < window->nr_contig_chunks; i++) {
                end = start + (window->num_pages[i] << PAGE_SHIFT);
                if (off >= start && off < end) {
                        if (iter) {
                                iter->index = i;
                                iter->offset = start;
                        }
                        if (nr_bytes)
                                *nr_bytes = end - off;
                        return (window->dma_addr[i] + (off - start));
                }
                start += (window->num_pages[i] << PAGE_SHIFT);
        }
        dev_err(scif_info.mdev.this_device,
                "%s %d BUG. Addr not found? window %p off 0x%llx\n",
                __func__, __LINE__, window, off);
        return SCIF_RMA_ERROR_CODE;
}

/*
 * Copy between rma window and temporary buffer
 */
static void scif_rma_local_cpu_copy(s64 offset, struct scif_window *window,
                                    u8 *temp, size_t rem_len, bool to_temp)
{
        void *window_virt;
        size_t loop_len;
        int offset_in_page;
        s64 end_offset;

        offset_in_page = offset & ~PAGE_MASK;
        loop_len = PAGE_SIZE - offset_in_page;

        if (rem_len < loop_len)
                loop_len = rem_len;

        window_virt = _get_local_va(offset, window, loop_len);
        if (!window_virt)
                return;
        if (to_temp)
                memcpy(temp, window_virt, loop_len);
        else
                memcpy(window_virt, temp, loop_len);

        offset += loop_len;
        temp += loop_len;
        rem_len -= loop_len;

        end_offset = window->offset +
                (window->nr_pages << PAGE_SHIFT);
        while (rem_len) {
                if (offset == end_offset) {
                        window = list_next_entry(window, list);
                        end_offset = window->offset +
                                (window->nr_pages << PAGE_SHIFT);
                }
                loop_len = min(PAGE_SIZE, rem_len);
                window_virt = _get_local_va(offset, window, loop_len);
                if (!window_virt)
                        return;
                if (to_temp)
                        memcpy(temp, window_virt, loop_len);
                else
                        memcpy(window_virt, temp, loop_len);
                offset  += loop_len;
                temp    += loop_len;
                rem_len -= loop_len;
        }
}

/**
 * scif_rma_completion_cb:
 * @data: RMA cookie
 *
 * RMA interrupt completion callback.
 */
static void scif_rma_completion_cb(void *data)
{
        struct scif_dma_comp_cb *comp_cb = data;

        /* Free DMA Completion CB. */
        if (comp_cb->dst_window)
                scif_rma_local_cpu_copy(comp_cb->dst_offset,
                                        comp_cb->dst_window,
                                        comp_cb->temp_buf +
                                        comp_cb->header_padding,
                                        comp_cb->len, false);
        scif_unmap_single(comp_cb->temp_phys, comp_cb->sdev,
                          SCIF_KMEM_UNALIGNED_BUF_SIZE);
        if (comp_cb->is_cache)
                kmem_cache_free(unaligned_cache,
                                comp_cb->temp_buf_to_free);
        else
                kfree(comp_cb->temp_buf_to_free);
}

/* Copies between temporary buffer and offsets provided in work */
static int
scif_rma_list_dma_copy_unaligned(struct scif_copy_work *work,
                                 u8 *temp, struct dma_chan *chan,
                                 bool src_local)
{
        struct scif_dma_comp_cb *comp_cb = work->comp_cb;
        dma_addr_t window_dma_addr, temp_dma_addr;
        dma_addr_t temp_phys = comp_cb->temp_phys;
        size_t loop_len, nr_contig_bytes = 0, remaining_len = work->len;
        int offset_in_ca, ret = 0;
        s64 end_offset, offset;
        struct scif_window *window;
        void *window_virt_addr;
        size_t tail_len;
        struct dma_async_tx_descriptor *tx;
        struct dma_device *dev = chan->device;
        dma_cookie_t cookie;

        if (src_local) {
                offset = work->dst_offset;
                window = work->dst_window;
        } else {
                offset = work->src_offset;
                window = work->src_window;
        }

        offset_in_ca = offset & (L1_CACHE_BYTES - 1);
        if (offset_in_ca) {
                loop_len = L1_CACHE_BYTES - offset_in_ca;
                loop_len = min(loop_len, remaining_len);
                window_virt_addr = ioremap_remote(offset, window,
                                                  loop_len,
                                                  work->remote_dev,
                                                  NULL);
                if (!window_virt_addr)
                        return -ENOMEM;
                if (src_local)
                        scif_unaligned_cpy_toio(window_virt_addr, temp,
                                                loop_len,
                                                work->ordered &&
                                                !(remaining_len - loop_len));
                else
                        scif_unaligned_cpy_fromio(temp, window_virt_addr,
                                                  loop_len, work->ordered &&
                                                  !(remaining_len - loop_len));
                iounmap_remote(window_virt_addr, loop_len, work);

                offset += loop_len;
                temp += loop_len;
                temp_phys += loop_len;
                remaining_len -= loop_len;
        }

        offset_in_ca = offset & ~PAGE_MASK;
        end_offset = window->offset +
                (window->nr_pages << PAGE_SHIFT);

        tail_len = remaining_len & (L1_CACHE_BYTES - 1);
        remaining_len -= tail_len;
        while (remaining_len) {
                if (offset == end_offset) {
                        window = list_next_entry(window, list);
                        end_offset = window->offset +
                                (window->nr_pages << PAGE_SHIFT);
                }
                if (scif_is_mgmt_node())
                        temp_dma_addr = temp_phys;
                else
                        /* Fix if we ever enable IOMMU on the card */
                        temp_dma_addr = (dma_addr_t)virt_to_phys(temp);
                window_dma_addr = scif_off_to_dma_addr(window, offset,
                                                       &nr_contig_bytes,
                                                       NULL);
                loop_len = min(nr_contig_bytes, remaining_len);
                if (src_local) {
                        if (work->ordered && !tail_len &&
                            !(remaining_len - loop_len) &&
                            loop_len != L1_CACHE_BYTES) {
                                /*
                                 * Break up the last chunk of the transfer into
                                 * two steps. if there is no tail to guarantee
                                 * DMA ordering. SCIF_DMA_POLLING inserts
                                 * a status update descriptor in step 1 which
                                 * acts as a double sided synchronization fence
                                 * for the DMA engine to ensure that the last
                                 * cache line in step 2 is updated last.
                                 */
                                /* Step 1) DMA: Body Length - L1_CACHE_BYTES. */
                                tx =
                                dev->device_prep_dma_memcpy(chan,
                                                            window_dma_addr,
                                                            temp_dma_addr,
                                                            loop_len -
                                                            L1_CACHE_BYTES,
                                                            DMA_PREP_FENCE);
                                if (!tx) {
                                        ret = -ENOMEM;
                                        goto err;
                                }
                                cookie = tx->tx_submit(tx);
                                if (dma_submit_error(cookie)) {
                                        ret = -ENOMEM;
                                        goto err;
                                }
                                dma_async_issue_pending(chan);
                                offset += (loop_len - L1_CACHE_BYTES);
                                temp_dma_addr += (loop_len - L1_CACHE_BYTES);
                                window_dma_addr += (loop_len - L1_CACHE_BYTES);
                                remaining_len -= (loop_len - L1_CACHE_BYTES);
                                loop_len = remaining_len;

                                /* Step 2) DMA: L1_CACHE_BYTES */
                                tx =

                                dev->device_prep_dma_memcpy(chan,
                                                            window_dma_addr,
                                                            temp_dma_addr,
                                                            loop_len, 0);
                                if (!tx) {
                                        ret = -ENOMEM;
                                        goto err;
                                }
                                cookie = tx->tx_submit(tx);
                                if (dma_submit_error(cookie)) {
                                        ret = -ENOMEM;
                                        goto err;
                                }
                                dma_async_issue_pending(chan);
                        } else {
                                tx =
                                dev->device_prep_dma_memcpy(chan,
                                                            window_dma_addr,
                                                            temp_dma_addr,
                                                            loop_len, 0);
                                if (!tx) {
                                        ret = -ENOMEM;
                                        goto err;
                                }
                                cookie = tx->tx_submit(tx);
                                if (dma_submit_error(cookie)) {
                                        ret = -ENOMEM;
                                        goto err;
                                }
                                dma_async_issue_pending(chan);
                        }
                } else {
                        tx = dev->device_prep_dma_memcpy(chan, temp_dma_addr,
                                        window_dma_addr, loop_len, 0);
                        if (!tx) {
                                ret = -ENOMEM;
                                goto err;
                        }
                        cookie = tx->tx_submit(tx);
                        if (dma_submit_error(cookie)) {
                                ret = -ENOMEM;
                                goto err;
                        }
                        dma_async_issue_pending(chan);
                }
                if (ret < 0)
                        goto err;
                offset += loop_len;
                temp += loop_len;
                temp_phys += loop_len;
                remaining_len -= loop_len;
                offset_in_ca = 0;
        }
        if (tail_len) {
                if (offset == end_offset) {
                        window = list_next_entry(window, list);
                        end_offset = window->offset +
                                (window->nr_pages << PAGE_SHIFT);
                }
                window_virt_addr = ioremap_remote(offset, window, tail_len,
                                                  work->remote_dev,
                                                  NULL);
                if (!window_virt_addr)
                        return -ENOMEM;
                /*
                 * The CPU copy for the tail bytes must be initiated only once
                 * previous DMA transfers for this endpoint have completed
                 * to guarantee ordering.
                 */
                if (work->ordered) {
                        struct scif_dev *rdev = work->remote_dev;

                        ret = scif_drain_dma_intr(rdev->sdev, chan);
                        if (ret)
                                return ret;
                }
                if (src_local)
                        scif_unaligned_cpy_toio(window_virt_addr, temp,
                                                tail_len, work->ordered);
                else
                        scif_unaligned_cpy_fromio(temp, window_virt_addr,
                                                  tail_len, work->ordered);
                iounmap_remote(window_virt_addr, tail_len, work);
        }
        tx = dev->device_prep_dma_memcpy(chan, 0, 0, 0, DMA_PREP_INTERRUPT);
        if (!tx) {
                ret = -ENOMEM;
                return ret;
        }
        tx->callback = &scif_rma_completion_cb;
        tx->callback_param = comp_cb;
        cookie = tx->tx_submit(tx);

        if (dma_submit_error(cookie)) {
                ret = -ENOMEM;
                return ret;
        }
        dma_async_issue_pending(chan);
        return 0;
err:
        dev_err(scif_info.mdev.this_device,
                "%s %d Desc Prog Failed ret %d\n",
                __func__, __LINE__, ret);
        return ret;
}

/*
 * _scif_rma_list_dma_copy_aligned:
 *
 * Traverse all the windows and perform DMA copy.
 */
static int _scif_rma_list_dma_copy_aligned(struct scif_copy_work *work,
                                           struct dma_chan *chan)
{
        dma_addr_t src_dma_addr, dst_dma_addr;
        size_t loop_len, remaining_len, src_contig_bytes = 0;
        size_t dst_contig_bytes = 0;
        struct scif_window_iter src_win_iter;
        struct scif_window_iter dst_win_iter;
        s64 end_src_offset, end_dst_offset;
        struct scif_window *src_window = work->src_window;
        struct scif_window *dst_window = work->dst_window;
        s64 src_offset = work->src_offset, dst_offset = work->dst_offset;
        int ret = 0;
        struct dma_async_tx_descriptor *tx;
        struct dma_device *dev = chan->device;
        dma_cookie_t cookie;

        remaining_len = work->len;

        scif_init_window_iter(src_window, &src_win_iter);
        scif_init_window_iter(dst_window, &dst_win_iter);
        end_src_offset = src_window->offset +
                (src_window->nr_pages << PAGE_SHIFT);
        end_dst_offset = dst_window->offset +
                (dst_window->nr_pages << PAGE_SHIFT);
        while (remaining_len) {
                if (src_offset == end_src_offset) {
                        src_window = list_next_entry(src_window, list);
                        end_src_offset = src_window->offset +
                                (src_window->nr_pages << PAGE_SHIFT);
                        scif_init_window_iter(src_window, &src_win_iter);
                }
                if (dst_offset == end_dst_offset) {
                        dst_window = list_next_entry(dst_window, list);
                        end_dst_offset = dst_window->offset +
                                (dst_window->nr_pages << PAGE_SHIFT);
                        scif_init_window_iter(dst_window, &dst_win_iter);
                }

                /* compute dma addresses for transfer */
                src_dma_addr = scif_off_to_dma_addr(src_window, src_offset,
                                                    &src_contig_bytes,
                                                    &src_win_iter);
                dst_dma_addr = scif_off_to_dma_addr(dst_window, dst_offset,
                                                    &dst_contig_bytes,
                                                    &dst_win_iter);
                loop_len = min(src_contig_bytes, dst_contig_bytes);
                loop_len = min(loop_len, remaining_len);
                if (work->ordered && !(remaining_len - loop_len)) {
                        /*
                         * Break up the last chunk of the transfer into two
                         * steps to ensure that the last byte in step 2 is
                         * updated last.
                         */
                        /* Step 1) DMA: Body Length - 1 */
                        tx = dev->device_prep_dma_memcpy(chan, dst_dma_addr,
                                                         src_dma_addr,
                                                         loop_len - 1,
                                                         DMA_PREP_FENCE);
                        if (!tx) {
                                ret = -ENOMEM;
                                goto err;
                        }
                        cookie = tx->tx_submit(tx);
                        if (dma_submit_error(cookie)) {
                                ret = -ENOMEM;
                                goto err;
                        }
                        src_offset += (loop_len - 1);
                        dst_offset += (loop_len - 1);
                        src_dma_addr += (loop_len - 1);
                        dst_dma_addr += (loop_len - 1);
                        remaining_len -= (loop_len - 1);
                        loop_len = remaining_len;

                        /* Step 2) DMA: 1 BYTES */
                        tx = dev->device_prep_dma_memcpy(chan, dst_dma_addr,
                                        src_dma_addr, loop_len, 0);
                        if (!tx) {
                                ret = -ENOMEM;
                                goto err;
                        }
                        cookie = tx->tx_submit(tx);
                        if (dma_submit_error(cookie)) {
                                ret = -ENOMEM;
                                goto err;
                        }
                        dma_async_issue_pending(chan);
                } else {
                        tx = dev->device_prep_dma_memcpy(chan, dst_dma_addr,
                                        src_dma_addr, loop_len, 0);
                        if (!tx) {
                                ret = -ENOMEM;
                                goto err;
                        }
                        cookie = tx->tx_submit(tx);
                        if (dma_submit_error(cookie)) {
                                ret = -ENOMEM;
                                goto err;
                        }
                }
                src_offset += loop_len;
                dst_offset += loop_len;
                remaining_len -= loop_len;
        }
        return ret;
err:
        dev_err(scif_info.mdev.this_device,
                "%s %d Desc Prog Failed ret %d\n",
                __func__, __LINE__, ret);
        return ret;
}

/*
 * scif_rma_list_dma_copy_aligned:
 *
 * Traverse all the windows and perform DMA copy.
 */
static int scif_rma_list_dma_copy_aligned(struct scif_copy_work *work,
                                          struct dma_chan *chan)
{
        dma_addr_t src_dma_addr, dst_dma_addr;
        size_t loop_len, remaining_len, tail_len, src_contig_bytes = 0;
        size_t dst_contig_bytes = 0;
        int src_cache_off;
        s64 end_src_offset, end_dst_offset;
        struct scif_window_iter src_win_iter;
        struct scif_window_iter dst_win_iter;
        void *src_virt, *dst_virt;
        struct scif_window *src_window = work->src_window;
        struct scif_window *dst_window = work->dst_window;
        s64 src_offset = work->src_offset, dst_offset = work->dst_offset;
        int ret = 0;
        struct dma_async_tx_descriptor *tx;
        struct dma_device *dev = chan->device;
        dma_cookie_t cookie;

        remaining_len = work->len;
        scif_init_window_iter(src_window, &src_win_iter);
        scif_init_window_iter(dst_window, &dst_win_iter);

        src_cache_off = src_offset & (L1_CACHE_BYTES - 1);
        if (src_cache_off != 0) {
                /* Head */
                loop_len = L1_CACHE_BYTES - src_cache_off;
                loop_len = min(loop_len, remaining_len);
                src_dma_addr = __scif_off_to_dma_addr(src_window, src_offset);
                dst_dma_addr = __scif_off_to_dma_addr(dst_window, dst_offset);
                if (src_window->type == SCIF_WINDOW_SELF)
                        src_virt = _get_local_va(src_offset, src_window,
                                                 loop_len);
                else
                        src_virt = ioremap_remote(src_offset, src_window,
                                                  loop_len,
                                                  work->remote_dev, NULL);
                if (!src_virt)
                        return -ENOMEM;
                if (dst_window->type == SCIF_WINDOW_SELF)
                        dst_virt = _get_local_va(dst_offset, dst_window,
                                                 loop_len);
                else
                        dst_virt = ioremap_remote(dst_offset, dst_window,
                                                  loop_len,
                                                  work->remote_dev, NULL);
                if (!dst_virt) {
                        if (src_window->type != SCIF_WINDOW_SELF)
                                iounmap_remote(src_virt, loop_len, work);
                        return -ENOMEM;
                }
                if (src_window->type == SCIF_WINDOW_SELF)
                        scif_unaligned_cpy_toio(dst_virt, src_virt, loop_len,
                                                remaining_len == loop_len ?
                                                work->ordered : false);
                else
                        scif_unaligned_cpy_fromio(dst_virt, src_virt, loop_len,
                                                  remaining_len == loop_len ?
                                                  work->ordered : false);
                if (src_window->type != SCIF_WINDOW_SELF)
                        iounmap_remote(src_virt, loop_len, work);
                if (dst_window->type != SCIF_WINDOW_SELF)
                        iounmap_remote(dst_virt, loop_len, work);
                src_offset += loop_len;
                dst_offset += loop_len;
                remaining_len -= loop_len;
        }

        end_src_offset = src_window->offset +
                (src_window->nr_pages << PAGE_SHIFT);
        end_dst_offset = dst_window->offset +
                (dst_window->nr_pages << PAGE_SHIFT);
        tail_len = remaining_len & (L1_CACHE_BYTES - 1);
        remaining_len -= tail_len;
        while (remaining_len) {
                if (src_offset == end_src_offset) {
                        src_window = list_next_entry(src_window, list);
                        end_src_offset = src_window->offset +
                                (src_window->nr_pages << PAGE_SHIFT);
                        scif_init_window_iter(src_window, &src_win_iter);
                }
                if (dst_offset == end_dst_offset) {
                        dst_window = list_next_entry(dst_window, list);
                        end_dst_offset = dst_window->offset +
                                (dst_window->nr_pages << PAGE_SHIFT);
                        scif_init_window_iter(dst_window, &dst_win_iter);
                }

                /* compute dma addresses for transfer */
                src_dma_addr = scif_off_to_dma_addr(src_window, src_offset,
                                                    &src_contig_bytes,
                                                    &src_win_iter);
                dst_dma_addr = scif_off_to_dma_addr(dst_window, dst_offset,
                                                    &dst_contig_bytes,
                                                    &dst_win_iter);
                loop_len = min(src_contig_bytes, dst_contig_bytes);
                loop_len = min(loop_len, remaining_len);
                if (work->ordered && !tail_len &&
                    !(remaining_len - loop_len)) {
                        /*
                         * Break up the last chunk of the transfer into two
                         * steps. if there is no tail to gurantee DMA ordering.
                         * Passing SCIF_DMA_POLLING inserts a status update
                         * descriptor in step 1 which acts as a double sided
                         * synchronization fence for the DMA engine to ensure
                         * that the last cache line in step 2 is updated last.
                         */
                        /* Step 1) DMA: Body Length - L1_CACHE_BYTES. */
                        tx = dev->device_prep_dma_memcpy(chan, dst_dma_addr,
                                                         src_dma_addr,
                                                         loop_len -
                                                         L1_CACHE_BYTES,
                                                         DMA_PREP_FENCE);
                        if (!tx) {
                                ret = -ENOMEM;
                                goto err;
                        }
                        cookie = tx->tx_submit(tx);
                        if (dma_submit_error(cookie)) {
                                ret = -ENOMEM;
                                goto err;
                        }
                        dma_async_issue_pending(chan);
                        src_offset += (loop_len - L1_CACHE_BYTES);
                        dst_offset += (loop_len - L1_CACHE_BYTES);
                        src_dma_addr += (loop_len - L1_CACHE_BYTES);
                        dst_dma_addr += (loop_len - L1_CACHE_BYTES);
                        remaining_len -= (loop_len - L1_CACHE_BYTES);
                        loop_len = remaining_len;

                        /* Step 2) DMA: L1_CACHE_BYTES */
                        tx = dev->device_prep_dma_memcpy(chan, dst_dma_addr,
                                                         src_dma_addr,
                                                         loop_len, 0);
                        if (!tx) {
                                ret = -ENOMEM;
                                goto err;
                        }
                        cookie = tx->tx_submit(tx);
                        if (dma_submit_error(cookie)) {
                                ret = -ENOMEM;
                                goto err;
                        }
                        dma_async_issue_pending(chan);
                } else {
                        tx = dev->device_prep_dma_memcpy(chan, dst_dma_addr,
                                                         src_dma_addr,
                                                         loop_len, 0);
                        if (!tx) {
                                ret = -ENOMEM;
                                goto err;
                        }
                        cookie = tx->tx_submit(tx);
                        if (dma_submit_error(cookie)) {
                                ret = -ENOMEM;
                                goto err;
                        }
                        dma_async_issue_pending(chan);
                }
                src_offset += loop_len;
                dst_offset += loop_len;
                remaining_len -= loop_len;
        }
        remaining_len = tail_len;
        if (remaining_len) {
                loop_len = remaining_len;
                if (src_offset == end_src_offset)
                        src_window = list_next_entry(src_window, list);
                if (dst_offset == end_dst_offset)
                        dst_window = list_next_entry(dst_window, list);

                src_dma_addr = __scif_off_to_dma_addr(src_window, src_offset);
                dst_dma_addr = __scif_off_to_dma_addr(dst_window, dst_offset);
                /*
                 * The CPU copy for the tail bytes must be initiated only once
                 * previous DMA transfers for this endpoint have completed to
                 * guarantee ordering.
                 */
                if (work->ordered) {
                        struct scif_dev *rdev = work->remote_dev;

                        ret = scif_drain_dma_poll(rdev->sdev, chan);
                        if (ret)
                                return ret;
                }
                if (src_window->type == SCIF_WINDOW_SELF)
                        src_virt = _get_local_va(src_offset, src_window,
                                                 loop_len);
                else
                        src_virt = ioremap_remote(src_offset, src_window,
                                                  loop_len,
                                                  work->remote_dev, NULL);
                if (!src_virt)
                        return -ENOMEM;

                if (dst_window->type == SCIF_WINDOW_SELF)
                        dst_virt = _get_local_va(dst_offset, dst_window,
                                                 loop_len);
                else
                        dst_virt = ioremap_remote(dst_offset, dst_window,
                                                  loop_len,
                                                  work->remote_dev, NULL);
                if (!dst_virt) {
                        if (src_window->type != SCIF_WINDOW_SELF)
                                iounmap_remote(src_virt, loop_len, work);
                        return -ENOMEM;
                }

                if (src_window->type == SCIF_WINDOW_SELF)
                        scif_unaligned_cpy_toio(dst_virt, src_virt, loop_len,
                                                work->ordered);
                else
                        scif_unaligned_cpy_fromio(dst_virt, src_virt,
                                                  loop_len, work->ordered);
                if (src_window->type != SCIF_WINDOW_SELF)
                        iounmap_remote(src_virt, loop_len, work);

                if (dst_window->type != SCIF_WINDOW_SELF)
                        iounmap_remote(dst_virt, loop_len, work);
                remaining_len -= loop_len;
        }
        return ret;
err:
        dev_err(scif_info.mdev.this_device,
                "%s %d Desc Prog Failed ret %d\n",
                __func__, __LINE__, ret);
        return ret;
}

/*
 * scif_rma_list_cpu_copy:
 *
 * Traverse all the windows and perform CPU copy.
 */
static int scif_rma_list_cpu_copy(struct scif_copy_work *work)
{
        void *src_virt, *dst_virt;
        size_t loop_len, remaining_len;
        int src_page_off, dst_page_off;
        s64 src_offset = work->src_offset, dst_offset = work->dst_offset;
        struct scif_window *src_window = work->src_window;
        struct scif_window *dst_window = work->dst_window;
        s64 end_src_offset, end_dst_offset;
        int ret = 0;
        struct scif_window_iter src_win_iter;
        struct scif_window_iter dst_win_iter;

        remaining_len = work->len;

        scif_init_window_iter(src_window, &src_win_iter);
        scif_init_window_iter(dst_window, &dst_win_iter);
        while (remaining_len) {
                src_page_off = src_offset & ~PAGE_MASK;
                dst_page_off = dst_offset & ~PAGE_MASK;
                loop_len = min(PAGE_SIZE -
                               max(src_page_off, dst_page_off),
                               remaining_len);

                if (src_window->type == SCIF_WINDOW_SELF)
                        src_virt = _get_local_va(src_offset, src_window,
                                                 loop_len);
                else
                        src_virt = ioremap_remote(src_offset, src_window,
                                                  loop_len,
                                                  work->remote_dev,
                                                  &src_win_iter);
                if (!src_virt) {
                        ret = -ENOMEM;
                        goto error;
                }

                if (dst_window->type == SCIF_WINDOW_SELF)
                        dst_virt = _get_local_va(dst_offset, dst_window,
                                                 loop_len);
                else
                        dst_virt = ioremap_remote(dst_offset, dst_window,
                                                  loop_len,
                                                  work->remote_dev,
                                                  &dst_win_iter);
                if (!dst_virt) {
                        if (src_window->type == SCIF_WINDOW_PEER)
                                iounmap_remote(src_virt, loop_len, work);
                        ret = -ENOMEM;
                        goto error;
                }

                if (work->loopback) {
                        memcpy(dst_virt, src_virt, loop_len);
                } else {
                        if (src_window->type == SCIF_WINDOW_SELF)
                                memcpy_toio((void __iomem __force *)dst_virt,
                                            src_virt, loop_len);
                        else
                                memcpy_fromio(dst_virt,
                                              (void __iomem __force *)src_virt,
                                              loop_len);
                }
                if (src_window->type == SCIF_WINDOW_PEER)
                        iounmap_remote(src_virt, loop_len, work);

                if (dst_window->type == SCIF_WINDOW_PEER)
                        iounmap_remote(dst_virt, loop_len, work);

                src_offset += loop_len;
                dst_offset += loop_len;
                remaining_len -= loop_len;
                if (remaining_len) {
                        end_src_offset = src_window->offset +
                                (src_window->nr_pages << PAGE_SHIFT);
                        end_dst_offset = dst_window->offset +
                                (dst_window->nr_pages << PAGE_SHIFT);
                        if (src_offset == end_src_offset) {
                                src_window = list_next_entry(src_window, list);
                                scif_init_window_iter(src_window,
                                                      &src_win_iter);
                        }
                        if (dst_offset == end_dst_offset) {
                                dst_window = list_next_entry(dst_window, list);
                                scif_init_window_iter(dst_window,
                                                      &dst_win_iter);
                        }
                }
        }
error:
        return ret;
}

static int scif_rma_list_dma_copy_wrapper(struct scif_endpt *epd,
                                          struct scif_copy_work *work,
                                          struct dma_chan *chan, off_t loffset)
{
        int src_cache_off, dst_cache_off;
        s64 src_offset = work->src_offset, dst_offset = work->dst_offset;
        u8 *temp = NULL;
        bool src_local = true, dst_local = false;
        struct scif_dma_comp_cb *comp_cb;
        dma_addr_t src_dma_addr, dst_dma_addr;
        int err;

        if (is_dma_copy_aligned(chan->device, 1, 1, 1))
                return _scif_rma_list_dma_copy_aligned(work, chan);

        src_cache_off = src_offset & (L1_CACHE_BYTES - 1);
        dst_cache_off = dst_offset & (L1_CACHE_BYTES - 1);

        if (dst_cache_off == src_cache_off)
                return scif_rma_list_dma_copy_aligned(work, chan);

        if (work->loopback)
                return scif_rma_list_cpu_copy(work);
        src_dma_addr = __scif_off_to_dma_addr(work->src_window, src_offset);
        dst_dma_addr = __scif_off_to_dma_addr(work->dst_window, dst_offset);
        src_local = work->src_window->type == SCIF_WINDOW_SELF;
        dst_local = work->dst_window->type == SCIF_WINDOW_SELF;

        dst_local = dst_local;
        /* Allocate dma_completion cb */
        comp_cb = kzalloc(sizeof(*comp_cb), GFP_KERNEL);
        if (!comp_cb)
                goto error;

        work->comp_cb = comp_cb;
        comp_cb->cb_cookie = comp_cb;
        comp_cb->dma_completion_func = &scif_rma_completion_cb;

        if (work->len + (L1_CACHE_BYTES << 1) < SCIF_KMEM_UNALIGNED_BUF_SIZE) {
                comp_cb->is_cache = false;
                /* Allocate padding bytes to align to a cache line */
                temp = kmalloc(work->len + (L1_CACHE_BYTES << 1),
                               GFP_KERNEL);
                if (!temp)
                        goto free_comp_cb;
                comp_cb->temp_buf_to_free = temp;
                /* kmalloc(..) does not guarantee cache line alignment */
                if (!IS_ALIGNED((u64)temp, L1_CACHE_BYTES))
                        temp = PTR_ALIGN(temp, L1_CACHE_BYTES);
        } else {
                comp_cb->is_cache = true;
                temp = kmem_cache_alloc(unaligned_cache, GFP_KERNEL);
                if (!temp)
                        goto free_comp_cb;
                comp_cb->temp_buf_to_free = temp;
        }

        if (src_local) {
                temp += dst_cache_off;
                scif_rma_local_cpu_copy(work->src_offset, work->src_window,
                                        temp, work->len, true);
        } else {
                comp_cb->dst_window = work->dst_window;
                comp_cb->dst_offset = work->dst_offset;
                work->src_offset = work->src_offset - src_cache_off;
                comp_cb->len = work->len;
                work->len = ALIGN(work->len + src_cache_off, L1_CACHE_BYTES);
                comp_cb->header_padding = src_cache_off;
        }
        comp_cb->temp_buf = temp;

        err = scif_map_single(&comp_cb->temp_phys, temp,
                              work->remote_dev, SCIF_KMEM_UNALIGNED_BUF_SIZE);
        if (err)
                goto free_temp_buf;
        comp_cb->sdev = work->remote_dev;
        if (scif_rma_list_dma_copy_unaligned(work, temp, chan, src_local) < 0)
                goto free_temp_buf;
        if (!src_local)
                work->fence_type = SCIF_DMA_INTR;
        return 0;
free_temp_buf:
        if (comp_cb->is_cache)
                kmem_cache_free(unaligned_cache, comp_cb->temp_buf_to_free);
        else
                kfree(comp_cb->temp_buf_to_free);
free_comp_cb:
        kfree(comp_cb);
error:
        return -ENOMEM;
}

/**
 * scif_rma_copy:
 * @epd: end point descriptor.
 * @loffset: offset in local registered address space to/from which to copy
 * @addr: user virtual address to/from which to copy
 * @len: length of range to copy
 * @roffset: offset in remote registered address space to/from which to copy
 * @flags: flags
 * @dir: LOCAL->REMOTE or vice versa.
 * @last_chunk: true if this is the last chunk of a larger transfer
 *
 * Validate parameters, check if src/dst registered ranges requested for copy
 * are valid and initiate either CPU or DMA copy.
 */
static int scif_rma_copy(scif_epd_t epd, off_t loffset, unsigned long addr,
                         size_t len, off_t roffset, int flags,
                         enum scif_rma_dir dir, bool last_chunk)
{
        struct scif_endpt *ep = (struct scif_endpt *)epd;
        struct scif_rma_req remote_req;
        struct scif_rma_req req;
        struct scif_window *local_window = NULL;
        struct scif_window *remote_window = NULL;
        struct scif_copy_work copy_work;
        bool loopback;
        int err = 0;
        struct dma_chan *chan;
        struct scif_mmu_notif *mmn = NULL;
        bool cache = false;
        struct device *spdev;

        err = scif_verify_epd(ep);
        if (err)
                return err;

        if (flags && !(flags & (SCIF_RMA_USECPU | SCIF_RMA_USECACHE |
                                SCIF_RMA_SYNC | SCIF_RMA_ORDERED)))
                return -EINVAL;

        loopback = scifdev_self(ep->remote_dev) ? true : false;
        copy_work.fence_type = ((flags & SCIF_RMA_SYNC) && last_chunk) ?
                                SCIF_DMA_POLL : 0;
        copy_work.ordered = !!((flags & SCIF_RMA_ORDERED) && last_chunk);

        /* Use CPU for Mgmt node <-> Mgmt node copies */
        if (loopback && scif_is_mgmt_node()) {
                flags |= SCIF_RMA_USECPU;
                copy_work.fence_type = 0x0;
        }

        cache = scif_is_set_reg_cache(flags);

        remote_req.out_window = &remote_window;
        remote_req.offset = roffset;
        remote_req.nr_bytes = len;
        /*
         * If transfer is from local to remote then the remote window
         * must be writeable and vice versa.
         */
        remote_req.prot = dir == SCIF_LOCAL_TO_REMOTE ? VM_WRITE : VM_READ;
        remote_req.type = SCIF_WINDOW_PARTIAL;
        remote_req.head = &ep->rma_info.remote_reg_list;

        spdev = scif_get_peer_dev(ep->remote_dev);
        if (IS_ERR(spdev)) {
                err = PTR_ERR(spdev);
                return err;
        }

        if (addr && cache) {
                mutex_lock(&ep->rma_info.mmn_lock);
                mmn = scif_find_mmu_notifier(current->mm, &ep->rma_info);
                if (!mmn)
                        mmn = scif_add_mmu_notifier(current->mm, ep);
                mutex_unlock(&ep->rma_info.mmn_lock);
                if (IS_ERR(mmn)) {
                        scif_put_peer_dev(spdev);
                        return PTR_ERR(mmn);
                }
                cache = cache && !scif_rma_tc_can_cache(ep, len);
        }
        mutex_lock(&ep->rma_info.rma_lock);
        if (addr) {
                req.out_window = &local_window;
                req.nr_bytes = ALIGN(len + (addr & ~PAGE_MASK),
                                     PAGE_SIZE);
                req.va_for_temp = addr & PAGE_MASK;
                req.prot = (dir == SCIF_LOCAL_TO_REMOTE ?
                            VM_READ : VM_WRITE | VM_READ);
                /* Does a valid local window exist? */
                if (mmn) {
                        spin_lock(&ep->rma_info.tc_lock);
                        req.head = &mmn->tc_reg_list;
                        err = scif_query_tcw(ep, &req);
                        spin_unlock(&ep->rma_info.tc_lock);
                }
                if (!mmn || err) {
                        err = scif_register_temp(epd, req.va_for_temp,
                                                 req.nr_bytes, req.prot,
                                                 &loffset, &local_window);
                        if (err) {
                                mutex_unlock(&ep->rma_info.rma_lock);
                                goto error;
                        }
                        if (!cache)
                                goto skip_cache;
                        atomic_inc(&ep->rma_info.tcw_refcount);
                        atomic_add_return(local_window->nr_pages,
                                          &ep->rma_info.tcw_total_pages);
                        if (mmn) {
                                spin_lock(&ep->rma_info.tc_lock);
                                scif_insert_tcw(local_window,
                                                &mmn->tc_reg_list);
                                spin_unlock(&ep->rma_info.tc_lock);
                        }
                }
skip_cache:
                loffset = local_window->offset +
                                (addr - local_window->va_for_temp);
        } else {
                req.out_window = &local_window;
                req.offset = loffset;
                /*
                 * If transfer is from local to remote then the self window
                 * must be readable and vice versa.
                 */
                req.prot = dir == SCIF_LOCAL_TO_REMOTE ? VM_READ : VM_WRITE;
                req.nr_bytes = len;
                req.type = SCIF_WINDOW_PARTIAL;
                req.head = &ep->rma_info.reg_list;
                /* Does a valid local window exist? */
                err = scif_query_window(&req);
                if (err) {
                        mutex_unlock(&ep->rma_info.rma_lock);
                        goto error;
                }
        }

        /* Does a valid remote window exist? */
        err = scif_query_window(&remote_req);
        if (err) {
                mutex_unlock(&ep->rma_info.rma_lock);
                goto error;
        }

        /*
         * Prepare copy_work for submitting work to the DMA kernel thread
         * or CPU copy routine.
         */
        copy_work.len = len;
        copy_work.loopback = loopback;
        copy_work.remote_dev = ep->remote_dev;
        if (dir == SCIF_LOCAL_TO_REMOTE) {
                copy_work.src_offset = loffset;
                copy_work.src_window = local_window;
                copy_work.dst_offset = roffset;
                copy_work.dst_window = remote_window;
        } else {
                copy_work.src_offset = roffset;
                copy_work.src_window = remote_window;
                copy_work.dst_offset = loffset;
                copy_work.dst_window = local_window;
        }

        if (flags & SCIF_RMA_USECPU) {
                scif_rma_list_cpu_copy(&copy_work);
        } else {
                chan = ep->rma_info.dma_chan;
                err = scif_rma_list_dma_copy_wrapper(epd, &copy_work,
                                                     chan, loffset);
        }
        if (addr && !cache)
                atomic_inc(&ep->rma_info.tw_refcount);

        mutex_unlock(&ep->rma_info.rma_lock);

        if (last_chunk) {
                struct scif_dev *rdev = ep->remote_dev;

                if (copy_work.fence_type == SCIF_DMA_POLL)
                        err = scif_drain_dma_poll(rdev->sdev,
                                                  ep->rma_info.dma_chan);
                else if (copy_work.fence_type == SCIF_DMA_INTR)
                        err = scif_drain_dma_intr(rdev->sdev,
                                                  ep->rma_info.dma_chan);
        }

        if (addr && !cache)
                scif_queue_for_cleanup(local_window, &scif_info.rma);
        scif_put_peer_dev(spdev);
        return err;
error:
        if (err) {
                if (addr && local_window && !cache)
                        scif_destroy_window(ep, local_window);
                dev_err(scif_info.mdev.this_device,
                        "%s %d err %d len 0x%lx\n",
                        __func__, __LINE__, err, len);
        }
        scif_put_peer_dev(spdev);
        return err;
}

int scif_readfrom(scif_epd_t epd, off_t loffset, size_t len,
                  off_t roffset, int flags)
{
        int err;

        dev_dbg(scif_info.mdev.this_device,
                "SCIFAPI readfrom: ep %p loffset 0x%lx len 0x%lx offset 0x%lx flags 0x%x\n",
                epd, loffset, len, roffset, flags);
        if (scif_unaligned(loffset, roffset)) {
                while (len > SCIF_MAX_UNALIGNED_BUF_SIZE) {
                        err = scif_rma_copy(epd, loffset, 0x0,
                                            SCIF_MAX_UNALIGNED_BUF_SIZE,
                                            roffset, flags,
                                            SCIF_REMOTE_TO_LOCAL, false);
                        if (err)
                                goto readfrom_err;
                        loffset += SCIF_MAX_UNALIGNED_BUF_SIZE;
                        roffset += SCIF_MAX_UNALIGNED_BUF_SIZE;
                        len -= SCIF_MAX_UNALIGNED_BUF_SIZE;
                }
        }
        err = scif_rma_copy(epd, loffset, 0x0, len,
                            roffset, flags, SCIF_REMOTE_TO_LOCAL, true);
readfrom_err:
        return err;
}
EXPORT_SYMBOL_GPL(scif_readfrom);

int scif_writeto(scif_epd_t epd, off_t loffset, size_t len,
                 off_t roffset, int flags)
{
        int err;

        dev_dbg(scif_info.mdev.this_device,
                "SCIFAPI writeto: ep %p loffset 0x%lx len 0x%lx roffset 0x%lx flags 0x%x\n",
                epd, loffset, len, roffset, flags);
        if (scif_unaligned(loffset, roffset)) {
                while (len > SCIF_MAX_UNALIGNED_BUF_SIZE) {
                        err = scif_rma_copy(epd, loffset, 0x0,
                                            SCIF_MAX_UNALIGNED_BUF_SIZE,
                                            roffset, flags,
                                            SCIF_LOCAL_TO_REMOTE, false);
                        if (err)
                                goto writeto_err;
                        loffset += SCIF_MAX_UNALIGNED_BUF_SIZE;
                        roffset += SCIF_MAX_UNALIGNED_BUF_SIZE;
                        len -= SCIF_MAX_UNALIGNED_BUF_SIZE;
                }
        }
        err = scif_rma_copy(epd, loffset, 0x0, len,
                            roffset, flags, SCIF_LOCAL_TO_REMOTE, true);
writeto_err:
        return err;
}
EXPORT_SYMBOL_GPL(scif_writeto);

int scif_vreadfrom(scif_epd_t epd, void *addr, size_t len,
                   off_t roffset, int flags)
{
        int err;

        dev_dbg(scif_info.mdev.this_device,
                "SCIFAPI vreadfrom: ep %p addr %p len 0x%lx roffset 0x%lx flags 0x%x\n",
                epd, addr, len, roffset, flags);
        if (scif_unaligned((off_t __force)addr, roffset)) {
                if (len > SCIF_MAX_UNALIGNED_BUF_SIZE)
                        flags &= ~SCIF_RMA_USECACHE;

                while (len > SCIF_MAX_UNALIGNED_BUF_SIZE) {
                        err = scif_rma_copy(epd, 0, (u64)addr,
                                            SCIF_MAX_UNALIGNED_BUF_SIZE,
                                            roffset, flags,
                                            SCIF_REMOTE_TO_LOCAL, false);
                        if (err)
                                goto vreadfrom_err;
                        addr += SCIF_MAX_UNALIGNED_BUF_SIZE;
                        roffset += SCIF_MAX_UNALIGNED_BUF_SIZE;
                        len -= SCIF_MAX_UNALIGNED_BUF_SIZE;
                }
        }
        err = scif_rma_copy(epd, 0, (u64)addr, len,
                            roffset, flags, SCIF_REMOTE_TO_LOCAL, true);
vreadfrom_err:
        return err;
}
EXPORT_SYMBOL_GPL(scif_vreadfrom);

int scif_vwriteto(scif_epd_t epd, void *addr, size_t len,
                  off_t roffset, int flags)
{
        int err;

        dev_dbg(scif_info.mdev.this_device,
                "SCIFAPI vwriteto: ep %p addr %p len 0x%lx roffset 0x%lx flags 0x%x\n",
                epd, addr, len, roffset, flags);
        if (scif_unaligned((off_t __force)addr, roffset)) {
                if (len > SCIF_MAX_UNALIGNED_BUF_SIZE)
                        flags &= ~SCIF_RMA_USECACHE;

                while (len > SCIF_MAX_UNALIGNED_BUF_SIZE) {
                        err = scif_rma_copy(epd, 0, (u64)addr,
                                            SCIF_MAX_UNALIGNED_BUF_SIZE,
                                            roffset, flags,
                                            SCIF_LOCAL_TO_REMOTE, false);
                        if (err)
                                goto vwriteto_err;
                        addr += SCIF_MAX_UNALIGNED_BUF_SIZE;
                        roffset += SCIF_MAX_UNALIGNED_BUF_SIZE;
                        len -= SCIF_MAX_UNALIGNED_BUF_SIZE;
                }
        }
        err = scif_rma_copy(epd, 0, (u64)addr, len,
                            roffset, flags, SCIF_LOCAL_TO_REMOTE, true);
vwriteto_err:
        return err;
}
EXPORT_SYMBOL_GPL(scif_vwriteto);