/*-
 * SPDX-License-Identifier: BSD-2-Clause
 *
 * Copyright (c) 1997, 1998 Justin T. Gibbs.
 * All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions, and the following disclaimer,
 *    without modification, immediately at the beginning of the file.
 * 2. The name of the author may not be used to endorse or promote products
 *    derived from this software without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
 * ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE FOR
 * ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
 * SUCH DAMAGE.
 */

/*
 * From amd64/busdma_machdep.c, r204214
 */

#include <sys/param.h>
#include <sys/systm.h>
#include <sys/malloc.h>
#include <sys/bus.h>
#include <sys/interrupt.h>
#include <sys/kernel.h>
#include <sys/ktr.h>
#include <sys/lock.h>
#include <sys/proc.h>
#include <sys/memdesc.h>
#include <sys/mutex.h>
#include <sys/sysctl.h>
#include <sys/uio.h>

#include <vm/vm.h>
#include <vm/vm_extern.h>
#include <vm/vm_kern.h>
#include <vm/vm_page.h>
#include <vm/vm_map.h>

#include <machine/atomic.h>
#include <machine/bus.h>
#include <machine/cpufunc.h>
#include <machine/md_var.h>

#include "iommu_if.h"

#define MAX_BPAGES MIN(8192, physmem/40)

struct bounce_page;
struct bounce_zone;

struct bus_dma_tag {
        bus_size_t        alignment;
        bus_addr_t        boundary;
        bus_addr_t        lowaddr;
        bus_addr_t        highaddr;
        bus_size_t        maxsize;
        bus_size_t        maxsegsz;
        u_int             nsegments;
        int               flags;
        int               map_count;
        bus_dma_lock_t   *lockfunc;
        void             *lockfuncarg;
        struct bounce_zone *bounce_zone;
        device_t          iommu;
        void             *iommu_cookie;
};

static SYSCTL_NODE(_hw, OID_AUTO, busdma, CTLFLAG_RD | CTLFLAG_MPSAFE, 0,
    "Busdma parameters");

struct bus_dmamap {
        STAILQ_HEAD(, bounce_page) bpages;
        int                    pagesneeded;
        int                    pagesreserved;
        bus_dma_tag_t          dmat;
        struct memdesc         mem;
        bus_dma_segment_t     *segments;
        int                    nsegs;
        bus_dmamap_callback_t *callback;
        void                  *callback_arg;
        __sbintime_t           queued_time;
        STAILQ_ENTRY(bus_dmamap) links;
        int                    contigalloc;
};

static MALLOC_DEFINE(M_BUSDMA, "busdma", "busdma metadata");

#define dmat_alignment(dmat)    ((dmat)->alignment)
#define dmat_bounce_flags(dmat) (0)
#define dmat_boundary(dmat)     ((dmat)->boundary)
#define dmat_flags(dmat)        ((dmat)->flags)
#define dmat_highaddr(dmat)     ((dmat)->highaddr)
#define dmat_lowaddr(dmat)      ((dmat)->lowaddr)
#define dmat_lockfunc(dmat)     ((dmat)->lockfunc)
#define dmat_lockfuncarg(dmat)  ((dmat)->lockfuncarg)
#define dmat_maxsegsz(dmat)     ((dmat)->maxsegsz)
#define dmat_nsegments(dmat)    ((dmat)->nsegments)

#include "../../kern/subr_busdma_bounce.c"

/*
 * Returns true if the address falls within the tag's exclusion window, or
 * fails to meet its alignment requirements.
 */
static __inline bool
must_bounce(bus_dma_tag_t dmat, bus_addr_t paddr)
{

        if (dmat->iommu == NULL && paddr > dmat->lowaddr &&
            paddr <= dmat->highaddr)
                return (true);
        if (!vm_addr_align_ok(paddr, dmat->alignment))
                return (true);

        return (false);
}

#define BUS_DMA_COULD_BOUNCE    BUS_DMA_BUS3
#define BUS_DMA_MIN_ALLOC_COMP  BUS_DMA_BUS4
/*
 * Allocate a device specific dma_tag.
 */
int
bus_dma_tag_create(bus_dma_tag_t parent, bus_size_t alignment,
                   bus_addr_t boundary, bus_addr_t lowaddr,
                   bus_addr_t highaddr, bus_dma_filter_t *filter,
                   void *filterarg, bus_size_t maxsize, int nsegments,
                   bus_size_t maxsegsz, int flags, bus_dma_lock_t *lockfunc,
                   void *lockfuncarg, bus_dma_tag_t *dmat)
{
        bus_dma_tag_t newtag;
        int error = 0;

        /* Basic sanity checking */
        if (boundary != 0 && boundary < maxsegsz)
                maxsegsz = boundary;

        if (maxsegsz == 0) {
                return (EINVAL);
        }

        /* Filters are no longer supported. */
        if (filter != NULL || filterarg != NULL)
                return (EINVAL);

        /* Return a NULL tag on failure */
        *dmat = NULL;

        newtag = (bus_dma_tag_t)malloc(sizeof(*newtag), M_DEVBUF,
            M_ZERO | M_NOWAIT);
        if (newtag == NULL) {
                CTR4(KTR_BUSDMA, "%s returned tag %p tag flags 0x%x error %d",
                    __func__, newtag, 0, error);
                return (ENOMEM);
        }

        newtag->alignment = alignment;
        newtag->boundary = boundary;
        newtag->lowaddr = trunc_page((vm_paddr_t)lowaddr) + (PAGE_SIZE - 1);
        newtag->highaddr = trunc_page((vm_paddr_t)highaddr) + (PAGE_SIZE - 1);
        newtag->maxsize = maxsize;
        newtag->nsegments = nsegments;
        newtag->maxsegsz = maxsegsz;
        newtag->flags = flags;
        newtag->map_count = 0;
        if (lockfunc != NULL) {
                newtag->lockfunc = lockfunc;
                newtag->lockfuncarg = lockfuncarg;
        } else {
                newtag->lockfunc = _busdma_dflt_lock;
                newtag->lockfuncarg = NULL;
        }

        /* Take into account any restrictions imposed by our parent tag */
        if (parent != NULL) {
                newtag->lowaddr = MIN(parent->lowaddr, newtag->lowaddr);
                newtag->highaddr = MAX(parent->highaddr, newtag->highaddr);
                if (newtag->boundary == 0)
                        newtag->boundary = parent->boundary;
                else if (parent->boundary != 0)
                        newtag->boundary = MIN(parent->boundary,
                                               newtag->boundary);

                newtag->iommu = parent->iommu;
                newtag->iommu_cookie = parent->iommu_cookie;
        }

        if (newtag->lowaddr < ptoa((vm_paddr_t)Maxmem) && newtag->iommu == NULL)
                newtag->flags |= BUS_DMA_COULD_BOUNCE;

        if (newtag->alignment > 1)
                newtag->flags |= BUS_DMA_COULD_BOUNCE;

        if (((newtag->flags & BUS_DMA_COULD_BOUNCE) != 0) &&
            (flags & BUS_DMA_ALLOCNOW) != 0) {
                struct bounce_zone *bz;

                /* Must bounce */

                if ((error = alloc_bounce_zone(newtag)) != 0) {
                        free(newtag, M_DEVBUF);
                        return (error);
                }
                bz = newtag->bounce_zone;

                if (ptoa(bz->total_bpages) < maxsize) {
                        int pages;

                        pages = atop(maxsize) - bz->total_bpages;

                        /* Add pages to our bounce pool */
                        if (alloc_bounce_pages(newtag, pages) < pages)
                                error = ENOMEM;
                }
                /* Performed initial allocation */
                newtag->flags |= BUS_DMA_MIN_ALLOC_COMP;
        }

        if (error != 0) {
                free(newtag, M_DEVBUF);
        } else {
                *dmat = newtag;
        }
        CTR4(KTR_BUSDMA, "%s returned tag %p tag flags 0x%x error %d",
            __func__, newtag, (newtag != NULL ? newtag->flags : 0), error);
        return (error);
}

void
bus_dma_template_clone(bus_dma_template_t *t, bus_dma_tag_t dmat)
{

        if (t == NULL || dmat == NULL)
                return;

        t->alignment = dmat->alignment;
        t->boundary = dmat->boundary;
        t->lowaddr = dmat->lowaddr;
        t->highaddr = dmat->highaddr;
        t->maxsize = dmat->maxsize;
        t->nsegments = dmat->nsegments;
        t->maxsegsize = dmat->maxsegsz;
        t->flags = dmat->flags;
        t->lockfunc = dmat->lockfunc;
        t->lockfuncarg = dmat->lockfuncarg;
}

int
bus_dma_tag_set_domain(bus_dma_tag_t dmat, int domain)
{

        return (0);
}

int
bus_dma_tag_destroy(bus_dma_tag_t dmat)
{
        int error = 0;

        if (dmat != NULL) {
                if (dmat->map_count != 0) {
                        error = EBUSY;
                        goto out;
                }

                free(dmat, M_DEVBUF);
        }
out:
        CTR3(KTR_BUSDMA, "%s tag %p error %d", __func__, dmat, error);
        return (error);
}

/*
 * Allocate a handle for mapping from kva/uva/physical
 * address space into bus device space.
 */
int
bus_dmamap_create(bus_dma_tag_t dmat, int flags, bus_dmamap_t *mapp)
{
        int error;

        error = 0;

        *mapp = (bus_dmamap_t)malloc(sizeof(**mapp), M_DEVBUF,
                                     M_NOWAIT | M_ZERO);
        if (*mapp == NULL) {
                CTR3(KTR_BUSDMA, "%s: tag %p error %d",
                    __func__, dmat, ENOMEM);
                return (ENOMEM);
        }

        /* Initialize the new map */
        STAILQ_INIT(&((*mapp)->bpages));

        /*
         * Bouncing might be required if the driver asks for an active
         * exclusion region, a data alignment that is stricter than 1, and/or
         * an active address boundary.
         */
        if (dmat->flags & BUS_DMA_COULD_BOUNCE) {
                /* Must bounce */
                struct bounce_zone *bz;
                int maxpages;

                if (dmat->bounce_zone == NULL) {
                        if ((error = alloc_bounce_zone(dmat)) != 0)
                                return (error);
                }
                bz = dmat->bounce_zone;

                /*
                 * Attempt to add pages to our pool on a per-instance
                 * basis up to a sane limit.
                 */
                if (dmat->alignment > 1)
                        maxpages = MAX_BPAGES;
                else
                        maxpages = MIN(MAX_BPAGES, Maxmem -atop(dmat->lowaddr));
                if ((dmat->flags & BUS_DMA_MIN_ALLOC_COMP) == 0
                 || (bz->map_count > 0 && bz->total_bpages < maxpages)) {
                        int pages;

                        pages = MAX(atop(dmat->maxsize), 1);
                        pages = MIN(maxpages - bz->total_bpages, pages);
                        pages = MAX(pages, 1);
                        if (alloc_bounce_pages(dmat, pages) < pages)
                                error = ENOMEM;

                        if ((dmat->flags & BUS_DMA_MIN_ALLOC_COMP) == 0) {
                                if (error == 0)
                                        dmat->flags |= BUS_DMA_MIN_ALLOC_COMP;
                        } else {
                                error = 0;
                        }
                }
                bz->map_count++;
        }

        (*mapp)->nsegs = 0;
        (*mapp)->segments = (bus_dma_segment_t *)malloc(
            sizeof(bus_dma_segment_t) * dmat->nsegments, M_DEVBUF,
            M_NOWAIT);
        if ((*mapp)->segments == NULL) {
                CTR3(KTR_BUSDMA, "%s: tag %p error %d",
                    __func__, dmat, ENOMEM);
                return (ENOMEM);
        }

        if (error == 0)
                dmat->map_count++;
        CTR4(KTR_BUSDMA, "%s: tag %p tag flags 0x%x error %d",
            __func__, dmat, dmat->flags, error);
        return (error);
}

/*
 * Destroy a handle for mapping from kva/uva/physical
 * address space into bus device space.
 */
int
bus_dmamap_destroy(bus_dma_tag_t dmat, bus_dmamap_t map)
{
        if (dmat->flags & BUS_DMA_COULD_BOUNCE) {
                if (STAILQ_FIRST(&map->bpages) != NULL) {
                        CTR3(KTR_BUSDMA, "%s: tag %p error %d",
                            __func__, dmat, EBUSY);
                        return (EBUSY);
                }
                if (dmat->bounce_zone)
                        dmat->bounce_zone->map_count--;
        }
        free(map->segments, M_DEVBUF);
        free(map, M_DEVBUF);
        dmat->map_count--;
        CTR2(KTR_BUSDMA, "%s: tag %p error 0", __func__, dmat);
        return (0);
}

/*
 * Allocate a piece of memory that can be efficiently mapped into
 * bus device space based on the constraints lited in the dma tag.
 * A dmamap to for use with dmamap_load is also allocated.
 */
int
bus_dmamem_alloc(bus_dma_tag_t dmat, void** vaddr, int flags,
                 bus_dmamap_t *mapp)
{
        vm_memattr_t attr;
        int mflags;

        if (flags & BUS_DMA_NOWAIT)
                mflags = M_NOWAIT;
        else
                mflags = M_WAITOK;

        bus_dmamap_create(dmat, flags, mapp);

        if (flags & BUS_DMA_ZERO)
                mflags |= M_ZERO;
        if (flags & BUS_DMA_NOCACHE)
                attr = VM_MEMATTR_UNCACHEABLE;
        else
                attr = VM_MEMATTR_DEFAULT;

        /* 
         * XXX:
         * (dmat->alignment <= dmat->maxsize) is just a quick hack; the exact
         * alignment guarantees of malloc need to be nailed down, and the
         * code below should be rewritten to take that into account.
         *
         * In the meantime, we'll warn the user if malloc gets it wrong.
         */
        if ((dmat->maxsize <= PAGE_SIZE) &&
           (dmat->alignment <= dmat->maxsize) &&
            dmat->lowaddr >= ptoa((vm_paddr_t)Maxmem) &&
            attr == VM_MEMATTR_DEFAULT) {
                *vaddr = malloc(dmat->maxsize, M_DEVBUF, mflags);
        } else {
                /*
                 * XXX Use Contigmalloc until it is merged into this facility
                 *     and handles multi-seg allocations.  Nobody is doing
                 *     multi-seg allocations yet though.
                 * XXX Certain AGP hardware does.
                 */
                *vaddr = kmem_alloc_contig(dmat->maxsize, mflags, 0ul,
                    dmat->lowaddr, dmat->alignment ? dmat->alignment : 1ul,
                    dmat->boundary, attr);
                (*mapp)->contigalloc = 1;
        }
        if (*vaddr == NULL) {
                CTR4(KTR_BUSDMA, "%s: tag %p tag flags 0x%x error %d",
                    __func__, dmat, dmat->flags, ENOMEM);
                return (ENOMEM);
        } else if (!vm_addr_align_ok(vtophys(*vaddr), dmat->alignment)) {
                printf("bus_dmamem_alloc failed to align memory properly.\n");
        }
        CTR4(KTR_BUSDMA, "%s: tag %p tag flags 0x%x error %d",
            __func__, dmat, dmat->flags, 0);
        return (0);
}

/*
 * Free a piece of memory and it's allociated dmamap, that was allocated
 * via bus_dmamem_alloc.
 */
void
bus_dmamem_free(bus_dma_tag_t dmat, void *vaddr, bus_dmamap_t map)
{

        if (!map->contigalloc)
                free(vaddr, M_DEVBUF);
        else
                kmem_free(vaddr, dmat->maxsize);
        bus_dmamap_destroy(dmat, map);
        CTR3(KTR_BUSDMA, "%s: tag %p flags 0x%x", __func__, dmat, dmat->flags);
}

static void
_bus_dmamap_count_phys(bus_dma_tag_t dmat, bus_dmamap_t map, vm_paddr_t buf,
    bus_size_t buflen, int flags)
{
        bus_addr_t curaddr;
        bus_size_t sgsize;

        if (map->pagesneeded == 0) {
                CTR4(KTR_BUSDMA, "lowaddr= %d Maxmem= %d, boundary= %d, "
                    "alignment= %d", dmat->lowaddr, ptoa((vm_paddr_t)Maxmem),
                    dmat->boundary, dmat->alignment);
                CTR2(KTR_BUSDMA, "map= %p, pagesneeded= %d", map, map->pagesneeded);
                /*
                 * Count the number of bounce pages
                 * needed in order to complete this transfer
                 */
                curaddr = buf;
                while (buflen != 0) {
                        sgsize = buflen;
                        if (must_bounce(dmat, curaddr)) {
                                sgsize = MIN(sgsize,
                                    PAGE_SIZE - (curaddr & PAGE_MASK));
                                map->pagesneeded++;
                        }
                        curaddr += sgsize;
                        buflen -= sgsize;
                }
                CTR1(KTR_BUSDMA, "pagesneeded= %d\n", map->pagesneeded);
        }
}

static void
_bus_dmamap_count_pages(bus_dma_tag_t dmat, bus_dmamap_t map, pmap_t pmap,
    void *buf, bus_size_t buflen, int flags)
{
        vm_offset_t vaddr;
        vm_offset_t vendaddr;
        bus_addr_t paddr;

        if (map->pagesneeded == 0) {
                CTR4(KTR_BUSDMA, "lowaddr= %d Maxmem= %d, boundary= %d, "
                    "alignment= %d", dmat->lowaddr, ptoa((vm_paddr_t)Maxmem),
                    dmat->boundary, dmat->alignment);
                CTR2(KTR_BUSDMA, "map= %p, pagesneeded= %d", map, map->pagesneeded);
                /*
                 * Count the number of bounce pages
                 * needed in order to complete this transfer
                 */
                vaddr = (vm_offset_t)buf;
                vendaddr = (vm_offset_t)buf + buflen;

                while (vaddr < vendaddr) {
                        bus_size_t sg_len;

                        sg_len = MIN(vendaddr - vaddr,
                            PAGE_SIZE - ((vm_offset_t)vaddr & PAGE_MASK));
                        if (pmap == kernel_pmap)
                                paddr = pmap_kextract(vaddr);
                        else
                                paddr = pmap_extract(pmap, vaddr);
                        if (must_bounce(dmat, paddr)) {
                                sg_len = roundup2(sg_len, dmat->alignment);
                                map->pagesneeded++;
                        }
                        vaddr += sg_len;
                }
                CTR1(KTR_BUSDMA, "pagesneeded= %d\n", map->pagesneeded);
        }
}

/*
 * Utility function to load a physical buffer.  segp contains
 * the starting segment on entrace, and the ending segment on exit.
 */
int
_bus_dmamap_load_phys(bus_dma_tag_t dmat,
                      bus_dmamap_t map,
                      vm_paddr_t buf, bus_size_t buflen,
                      int flags,
                      bus_dma_segment_t *segs,
                      int *segp)
{
        bus_addr_t curaddr;
        bus_size_t sgsize;
        int error;

        if (segs == NULL)
                segs = map->segments;

        if ((dmat->flags & BUS_DMA_COULD_BOUNCE) != 0) {
                _bus_dmamap_count_phys(dmat, map, buf, buflen, flags);
                if (map->pagesneeded != 0) {
                        error = _bus_dmamap_reserve_pages(dmat, map, flags);
                        if (error)
                                return (error);
                }
        }

        while (buflen > 0) {
                curaddr = buf;
                sgsize = buflen;
                if (map->pagesneeded != 0 && must_bounce(dmat, curaddr)) {
                        sgsize = MIN(sgsize, PAGE_SIZE - (curaddr & PAGE_MASK));
                        curaddr = add_bounce_page(dmat, map, 0, curaddr,
                            sgsize);
                }
                if (!_bus_dmamap_addsegs(dmat, map, curaddr, sgsize, segs,
                    segp))
                        break;
                buf += sgsize;
                buflen -= sgsize;
        }

        /*
         * Did we fit?
         */
        return (buflen != 0 ? EFBIG : 0); /* XXX better return value here? */
}

int
_bus_dmamap_load_ma(bus_dma_tag_t dmat, bus_dmamap_t map,
    struct vm_page **ma, bus_size_t tlen, int ma_offs, int flags,
    bus_dma_segment_t *segs, int *segp)
{

        return (bus_dmamap_load_ma_triv(dmat, map, ma, tlen, ma_offs, flags,
            segs, segp));
}

/*
 * Utility function to load a linear buffer.  segp contains
 * the starting segment on entrance, and the ending segment on exit.
 */
int
_bus_dmamap_load_buffer(bus_dma_tag_t dmat,
                        bus_dmamap_t map,
                        void *buf, bus_size_t buflen,
                        pmap_t pmap,
                        int flags,
                        bus_dma_segment_t *segs,
                        int *segp)
{
        bus_size_t sgsize;
        bus_addr_t curaddr;
        vm_offset_t kvaddr, vaddr;
        int error;

        if (segs == NULL)
                segs = map->segments;

        if ((dmat->flags & BUS_DMA_COULD_BOUNCE) != 0) {
                _bus_dmamap_count_pages(dmat, map, pmap, buf, buflen, flags);
                if (map->pagesneeded != 0) {
                        error = _bus_dmamap_reserve_pages(dmat, map, flags);
                        if (error)
                                return (error);
                }
        }

        vaddr = (vm_offset_t)buf;

        while (buflen > 0) {
                /*
                 * Get the physical address for this segment.
                 */
                if (pmap == kernel_pmap) {
                        curaddr = pmap_kextract(vaddr);
                        kvaddr = vaddr;
                } else {
                        curaddr = pmap_extract(pmap, vaddr);
                        kvaddr = 0;
                }

                /*
                 * Compute the segment size, and adjust counts.
                 */
                sgsize = MIN(buflen, PAGE_SIZE - (curaddr & PAGE_MASK));
                if (map->pagesneeded != 0 && must_bounce(dmat, curaddr)) {
                        sgsize = roundup2(sgsize, dmat->alignment);
                        sgsize = MIN(sgsize, buflen);
                        curaddr = add_bounce_page(dmat, map, kvaddr, curaddr,
                            sgsize);
                }

                if (!_bus_dmamap_addsegs(dmat, map, curaddr, sgsize, segs,
                    segp))
                        break;
                vaddr += sgsize;
                buflen -= MIN(sgsize, buflen); /* avoid underflow */
        }

        /*
         * Did we fit?
         */
        return (buflen != 0 ? EFBIG : 0); /* XXX better return value here? */
}

void
_bus_dmamap_waitok(bus_dma_tag_t dmat, bus_dmamap_t map,
                    struct memdesc *mem, bus_dmamap_callback_t *callback,
                    void *callback_arg)
{

        if (dmat->flags & BUS_DMA_COULD_BOUNCE) {
                map->dmat = dmat;
                map->mem = *mem;
                map->callback = callback;
                map->callback_arg = callback_arg;
        }
}

bus_dma_segment_t *
_bus_dmamap_complete(bus_dma_tag_t dmat, bus_dmamap_t map,
                     bus_dma_segment_t *segs, int nsegs, int error)
{

        map->nsegs = nsegs;
        if (segs != NULL)
                memcpy(map->segments, segs, map->nsegs*sizeof(segs[0]));
        if (dmat->iommu != NULL)
                IOMMU_MAP(dmat->iommu, map->segments, &map->nsegs,
                    dmat->lowaddr, dmat->highaddr, dmat->alignment,
                    dmat->boundary, dmat->iommu_cookie);

        if (segs != NULL)
                memcpy(segs, map->segments, map->nsegs*sizeof(segs[0]));
        else
                segs = map->segments;

        return (segs);
}

/*
 * Release the mapping held by map.
 */
void
bus_dmamap_unload(bus_dma_tag_t dmat, bus_dmamap_t map)
{
        if (dmat->iommu) {
                IOMMU_UNMAP(dmat->iommu, map->segments, map->nsegs, dmat->iommu_cookie);
                map->nsegs = 0;
        }

        free_bounce_pages(dmat, map);
}

void
bus_dmamap_sync(bus_dma_tag_t dmat, bus_dmamap_t map, bus_dmasync_op_t op)
{
        struct bounce_page *bpage;
        vm_offset_t datavaddr, tempvaddr;

        if ((bpage = STAILQ_FIRST(&map->bpages)) != NULL) {
                /*
                 * Handle data bouncing.  We might also
                 * want to add support for invalidating
                 * the caches on broken hardware
                 */
                CTR4(KTR_BUSDMA, "%s: tag %p tag flags 0x%x op 0x%x "
                    "performing bounce", __func__, dmat, dmat->flags, op);

                if (op & BUS_DMASYNC_PREWRITE) {
                        while (bpage != NULL) {
                                tempvaddr = 0;
                                datavaddr = bpage->datavaddr;
                                if (datavaddr == 0) {
                                        tempvaddr = pmap_quick_enter_page(
                                            bpage->datapage);
                                        datavaddr = tempvaddr |
                                            bpage->dataoffs;
                                }

                                bcopy((void *)datavaddr,
                                    (void *)bpage->vaddr, bpage->datacount);

                                if (tempvaddr != 0)
                                        pmap_quick_remove_page(tempvaddr);
                                bpage = STAILQ_NEXT(bpage, links);
                        }
                        dmat->bounce_zone->total_bounced++;
                }

                if (op & BUS_DMASYNC_POSTREAD) {
                        while (bpage != NULL) {
                                tempvaddr = 0;
                                datavaddr = bpage->datavaddr;
                                if (datavaddr == 0) {
                                        tempvaddr = pmap_quick_enter_page(
                                            bpage->datapage);
                                        datavaddr = tempvaddr |
                                            bpage->dataoffs;
                                }

                                bcopy((void *)bpage->vaddr,
                                    (void *)datavaddr, bpage->datacount);

                                if (tempvaddr != 0)
                                        pmap_quick_remove_page(tempvaddr);
                                bpage = STAILQ_NEXT(bpage, links);
                        }
                        dmat->bounce_zone->total_bounced++;
                }
        }

        powerpc_sync();
}

int
bus_dma_tag_set_iommu(bus_dma_tag_t tag, device_t iommu, void *cookie)
{
        tag->iommu = iommu;
        tag->iommu_cookie = cookie;

        return (0);
}