/*      $NetBSD: bus_dma.c,v 1.40 2023/12/17 14:54:49 andvar Exp $      */

/*-
 * Copyright (c) 1996, 1997, 1998 The NetBSD Foundation, Inc.
 * All rights reserved.
 *
 * This code is derived from software contributed to The NetBSD Foundation
 * by Jason R. Thorpe of the Numerical Aerospace Simulation Facility,
 * NASA Ames Research Center.
 *
 * 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.
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in the
 *    documentation and/or other materials provided with the distribution.
 *
 * THIS SOFTWARE IS PROVIDED BY THE NETBSD FOUNDATION, INC. 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 FOUNDATION 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.
 */
/*
 * bus_dma routines for vax. File copied from arm32/bus_dma.c.
 * NetBSD: bus_dma.c,v 1.11 1998/09/21 22:53:35 thorpej Exp
 */

#include <sys/cdefs.h>
__KERNEL_RCSID(0, "$NetBSD: bus_dma.c,v 1.40 2023/12/17 14:54:49 andvar Exp $");

#include <sys/param.h>
#include <sys/systm.h>
#include <sys/kernel.h>
#include <sys/proc.h>
#include <sys/buf.h>
#include <sys/reboot.h>
#include <sys/conf.h>
#include <sys/file.h>
#include <sys/kmem.h>
#include <sys/mbuf.h>
#include <sys/vnode.h>
#include <sys/device.h>

#include <uvm/uvm.h>

#define _VAX_BUS_DMA_PRIVATE
#include <machine/bus.h>

#include <machine/ka43.h>
#include <machine/sid.h>

extern  paddr_t avail_start, avail_end;
extern  vaddr_t virtual_avail;

int     _bus_dmamap_load_buffer(bus_dma_tag_t, bus_dmamap_t, void *,
            bus_size_t, struct vmspace *, int, vaddr_t *, int *, bool);
int     _bus_dma_inrange(bus_dma_segment_t *, int, bus_addr_t);
int     _bus_dmamem_alloc_range(bus_dma_tag_t, bus_size_t, bus_size_t,
            bus_size_t, bus_dma_segment_t*, int, int *, int, vaddr_t, vaddr_t);

static size_t
_bus_dmamap_mapsize(int const nsegments)
{
        KASSERT(nsegments > 0);
        return sizeof(struct vax_bus_dmamap) +
            (sizeof(bus_dma_segment_t) * (nsegments - 1));
}

/*
 * Common function for DMA map creation.  May be called by bus-specific
 * DMA map creation functions.
 */
int
_bus_dmamap_create(bus_dma_tag_t t, bus_size_t size, int nsegments,
        bus_size_t maxsegsz, bus_size_t boundary, int flags,
        bus_dmamap_t *dmamp)
{
        struct vax_bus_dmamap *map;
        void *mapstore;

#ifdef DEBUG_DMA
        printf("dmamap_create: t=%p size=%lx nseg=%x msegsz=%lx boundary=%lx flags=%x\n",
            t, size, nsegments, maxsegsz, boundary, flags);
#endif  /* DEBUG_DMA */

        /*
         * Allocate and initialize the DMA map.  The end of the map
         * is a variable-sized array of segments, so we allocate enough
         * room for them in one shot.
         *
         * Note we don't preserve the WAITOK or NOWAIT flags.  Preservation
         * of ALLOCNOW notifies others that we've reserved these resources,
         * and they are not to be freed.
         *
         * The bus_dmamap_t includes one bus_dma_segment_t, hence
         * the (nsegments - 1).
         */
        if ((mapstore = kmem_zalloc(_bus_dmamap_mapsize(nsegments),
            (flags & BUS_DMA_NOWAIT) ? KM_NOSLEEP : KM_SLEEP)) == NULL)
                return (ENOMEM);

        map = (struct vax_bus_dmamap *)mapstore;
        map->_dm_size = size;
        map->_dm_segcnt = nsegments;
        map->_dm_maxmaxsegsz = maxsegsz;
        map->_dm_boundary = boundary;
        map->_dm_flags = flags & ~(BUS_DMA_WAITOK|BUS_DMA_NOWAIT);
        map->dm_maxsegsz = maxsegsz;
        map->dm_mapsize = 0;            /* no valid mappings */
        map->dm_nsegs = 0;

        *dmamp = map;
#ifdef DEBUG_DMA
        printf("dmamap_create:map=%p\n", map);
#endif  /* DEBUG_DMA */
        return (0);
}

/*
 * Common function for DMA map destruction.  May be called by bus-specific
 * DMA map destruction functions.
 */
void
_bus_dmamap_destroy(bus_dma_tag_t t, bus_dmamap_t map)
{

#ifdef DEBUG_DMA
        printf("dmamap_destroy: t=%p map=%p\n", t, map);
#endif  /* DEBUG_DMA */
#ifdef DIAGNOSTIC
        if (map->dm_nsegs > 0)
                printf("bus_dmamap_destroy() called for map with valid mappings\n");
#endif  /* DIAGNOSTIC */
        kmem_free(map, _bus_dmamap_mapsize(map->_dm_segcnt));
}

/*
 * Common function for loading a DMA map with a linear buffer.  May
 * be called by bus-specific DMA map load functions.
 */
int
_bus_dmamap_load(bus_dma_tag_t t, bus_dmamap_t map, void *buf,
        bus_size_t buflen, struct proc *p, int flags)
{
        vaddr_t lastaddr = 0;
        int seg, error;
        struct vmspace *vm;

#ifdef DEBUG_DMA
        printf("dmamap_load: t=%p map=%p buf=%p len=%lx p=%p f=%d\n",
            t, map, buf, buflen, p, flags);
#endif  /* DEBUG_DMA */

        /*
         * Make sure that on error condition we return "no valid mappings".
         */
        map->dm_mapsize = 0;
        map->dm_nsegs = 0;
        KASSERT(map->dm_maxsegsz <= map->_dm_maxmaxsegsz);

        if (buflen > map->_dm_size)
                return (EINVAL);

        if (p != NULL) {
                vm = p->p_vmspace;
        } else {
                vm = vmspace_kernel();
        }

        seg = 0;
        error = _bus_dmamap_load_buffer(t, map, buf, buflen, vm, flags,
            &lastaddr, &seg, 1);
        if (error == 0) {
                map->dm_mapsize = buflen;
                map->dm_nsegs = seg + 1;
        }
#ifdef DEBUG_DMA
        printf("dmamap_load: error=%d\n", error);
#endif  /* DEBUG_DMA */
        return (error);
}

/*
 * Like _bus_dmamap_load(), but for mbufs.
 */
int
_bus_dmamap_load_mbuf(bus_dma_tag_t t, bus_dmamap_t map, struct mbuf *m0,
        int flags)
{
        vaddr_t lastaddr = 0;
        int seg, error;
        bool first;
        struct mbuf *m;

#ifdef DEBUG_DMA
        printf("dmamap_load_mbuf: t=%p map=%p m0=%p f=%d\n",
            t, map, m0, flags);
#endif  /* DEBUG_DMA */

        /*
         * Make sure that on error condition we return "no valid mappings."
         */
        map->dm_mapsize = 0;
        map->dm_nsegs = 0;
        KASSERT(map->dm_maxsegsz <= map->_dm_maxmaxsegsz);

#ifdef DIAGNOSTIC
        if ((m0->m_flags & M_PKTHDR) == 0)
                panic("_bus_dmamap_load_mbuf: no packet header");
#endif  /* DIAGNOSTIC */

        if (m0->m_pkthdr.len > map->_dm_size)
                return (EINVAL);

        first = true;
        seg = 0;
        error = 0;
        for (m = m0; m != NULL && error == 0; m = m->m_next, first = false) {
                if (m->m_len == 0)
                        continue;
#if 0
                switch (m->m_flags & (M_EXT|M_EXT_CLUSTER)) {
#if 0
                case M_EXT|M_EXT_CLUSTER:
                        KASSERT(m->m_ext.ext_paddr != M_PADDR_INVALID);
                        lastaddr = m->m_ext.ext_paddr
                            + (m->m_data - m->m_ext.ext_buf);
#endif
#if 1
    have_addr:
#endif
                        if (!first && ++seg >= map->_dm_segcnt) {
                                error = EFBIG;
                                continue;
                        }
                        map->dm_segs[seg].ds_addr = lastaddr;
                        map->dm_segs[seg].ds_len = m->m_len;
                        lastaddr += m->m_len;
                        continue;
#if 1
                case 0:
                        KASSERT(m->m_paddr != M_PADDR_INVALID);
                        lastaddr = m->m_paddr + M_BUFOFFSET(m)
                            + (m->m_data - M_BUFADDR(m));
                        goto have_addr;
#endif
                default:
                        break;
                }
#endif
                error = _bus_dmamap_load_buffer(t, map, m->m_data, m->m_len,
                    vmspace_kernel(), flags, &lastaddr, &seg, first);
        }
        if (error == 0) {
                map->dm_mapsize = m0->m_pkthdr.len;
                map->dm_nsegs = seg + 1;
        }
#ifdef DEBUG_DMA
        printf("dmamap_load_mbuf: error=%d\n", error);
#endif  /* DEBUG_DMA */
        return (error);
}

/*
 * Like _bus_dmamap_load(), but for uios.
 */
int
_bus_dmamap_load_uio(bus_dma_tag_t t, bus_dmamap_t map, struct uio *uio,
        int flags)
{
        vaddr_t lastaddr = 0;
        int seg, i, error;
        bool first;
        bus_size_t minlen, resid;
        struct iovec *iov;
        void *addr;

        /*
         * Make sure that on error condition we return "no valid mappings."
         */
        map->dm_mapsize = 0;
        map->dm_nsegs = 0;
        KASSERT(map->dm_maxsegsz <= map->_dm_maxmaxsegsz);

        resid = uio->uio_resid;
        iov = uio->uio_iov;

        first = true;
        seg = 0;
        error = 0;
        for (i = 0; i < uio->uio_iovcnt && resid != 0 && error == 0; i++) {
                /*
                 * Now at the first iovec to load.  Load each iovec
                 * until we have exhausted the residual count.
                 */
                minlen = resid < iov[i].iov_len ? resid : iov[i].iov_len;
                addr = (void *)iov[i].iov_base;

                error = _bus_dmamap_load_buffer(t, map, addr, minlen,
                    uio->uio_vmspace, flags, &lastaddr, &seg, first);
                first = false;

                resid -= minlen;
        }
        if (error == 0) {
                map->dm_mapsize = uio->uio_resid;
                map->dm_nsegs = seg + 1;
        }
        return (error);
}

/*
 * Like _bus_dmamap_load(), but for raw memory allocated with
 * bus_dmamem_alloc().
 */
int
_bus_dmamap_load_raw(bus_dma_tag_t t, bus_dmamap_t map, bus_dma_segment_t *segs,
        int nsegs, bus_size_t size, int flags)
{

        panic("_bus_dmamap_load_raw: not implemented");
}

/*
 * Common function for unloading a DMA map.  May be called by
 * bus-specific DMA map unload functions.
 */
void
_bus_dmamap_unload(bus_dma_tag_t t, bus_dmamap_t map)
{

#ifdef DEBUG_DMA
        printf("dmamap_unload: t=%p map=%p\n", t, map);
#endif  /* DEBUG_DMA */

        /*
         * No resources to free; just mark the mappings as
         * invalid.
         */
        map->dm_maxsegsz = map->_dm_maxmaxsegsz;
        map->dm_mapsize = 0;
        map->dm_nsegs = 0;
}

/*
 * Common function for DMA map synchronization.  May be called
 * by bus-specific DMA map synchronization functions.
 */
void
_bus_dmamap_sync(bus_dma_tag_t t, bus_dmamap_t map, bus_addr_t offset,
        bus_size_t len, int ops)
{
#ifdef DEBUG_DMA
        printf("dmamap_sync: t=%p map=%p offset=%lx len=%lx ops=%x\n",
            t, map, offset, len, ops);
#endif  /* DEBUG_DMA */
        /*
         * A vax only has snoop-cache, so this routine is a no-op.
         */
        return;
}

/*
 * Common function for DMA-safe memory allocation.  May be called
 * by bus-specific DMA memory allocation functions.
 */

int
_bus_dmamem_alloc(bus_dma_tag_t t, bus_size_t size, bus_size_t alignment,
        bus_size_t boundary, bus_dma_segment_t *segs,
        int nsegs, int *rsegs, int flags)
{
        int error;

        error =  (_bus_dmamem_alloc_range(t, size, alignment, boundary,
            segs, nsegs, rsegs, flags, round_page(avail_start),
            trunc_page(avail_end)));
        return(error);
}

/*
 * Common function for freeing DMA-safe memory.  May be called by
 * bus-specific DMA memory free functions.
 */
void
_bus_dmamem_free(bus_dma_tag_t t, bus_dma_segment_t *segs, int nsegs)
{
        struct vm_page *m;
        bus_addr_t addr;
        struct pglist mlist;
        int curseg;

#ifdef DEBUG_DMA
        printf("dmamem_free: t=%p segs=%p nsegs=%x\n", t, segs, nsegs);
#endif  /* DEBUG_DMA */

        /*
         * Build a list of pages to free back to the VM system.
         */
        TAILQ_INIT(&mlist);
        for (curseg = 0; curseg < nsegs; curseg++) {
                for (addr = segs[curseg].ds_addr;
                    addr < (segs[curseg].ds_addr + segs[curseg].ds_len);
                    addr += PAGE_SIZE) {
                        m = PHYS_TO_VM_PAGE(addr);
                        TAILQ_INSERT_TAIL(&mlist, m, pageq.queue);
                }
        }
        uvm_pglistfree(&mlist);
}

/*
 * Common function for mapping DMA-safe memory.  May be called by
 * bus-specific DMA memory map functions.
 */
int
_bus_dmamem_map(bus_dma_tag_t t, bus_dma_segment_t *segs, int nsegs,
        size_t size, void **kvap, int flags)
{
        vaddr_t va;
        bus_addr_t addr;
        int curseg;
        const uvm_flag_t kmflags =
            (flags & BUS_DMA_NOWAIT) != 0 ? UVM_KMF_NOWAIT : 0;

        /*
         * Special case (but common):
         * If there is only one physical segment then the already-mapped
         * virtual address is returned, since all physical memory is already
         * in the beginning of kernel virtual memory.
         */
        if (nsegs == 1) {
                *kvap = (void *)(segs[0].ds_addr | KERNBASE);
                /*
                 * KA43 (3100/m76) must have its DMA-safe memory accessed
                 * through DIAGMEM. Remap it here.
                 */
                if (vax_boardtype == VAX_BTYP_43) {
                        pmap_map((vaddr_t)*kvap, segs[0].ds_addr|KA43_DIAGMEM,
                            (segs[0].ds_addr|KA43_DIAGMEM) + size,
                            VM_PROT_READ|VM_PROT_WRITE);
                }
                return 0;
        }
        size = round_page(size);
        va = uvm_km_alloc(kernel_map, size, 0, UVM_KMF_VAONLY | kmflags);

        if (va == 0)
                return (ENOMEM);

        *kvap = (void *)va;

        for (curseg = 0; curseg < nsegs; curseg++) {
                for (addr = segs[curseg].ds_addr;
                    addr < (segs[curseg].ds_addr + segs[curseg].ds_len);
                    addr += PAGE_SIZE, va += PAGE_SIZE, size -= PAGE_SIZE) {
                        if (size == 0)
                                panic("_bus_dmamem_map: size botch");
                        if (vax_boardtype == VAX_BTYP_43)
                                addr |= KA43_DIAGMEM;
                        pmap_enter(pmap_kernel(), va, addr,
                            VM_PROT_READ | VM_PROT_WRITE,
                            VM_PROT_READ | VM_PROT_WRITE | PMAP_WIRED);
                }
        }
        pmap_update(pmap_kernel());
        return (0);
}

/*
 * Common function for unmapping DMA-safe memory.  May be called by
 * bus-specific DMA memory unmapping functions.
 */
void
_bus_dmamem_unmap(bus_dma_tag_t t, void *kva, size_t size)
{

#ifdef DEBUG_DMA
        printf("dmamem_unmap: t=%p kva=%p size=%lx\n", t, kva, size);
#endif  /* DEBUG_DMA */
#ifdef DIAGNOSTIC
        if ((u_long)kva & PGOFSET)
                panic("_bus_dmamem_unmap");
#endif  /* DIAGNOSTIC */

        /* Avoid free'ing if not mapped */
        if (kva < (void *)virtual_avail)
                return;

        size = round_page(size);
        pmap_remove(pmap_kernel(), (vaddr_t)kva, (vaddr_t)kva + size);
        pmap_update(pmap_kernel());
        uvm_km_free(kernel_map, (vaddr_t)kva, size, UVM_KMF_VAONLY);
}

/*
 * Common function for mmap(2)'ing DMA-safe memory.  May be called by
 * bus-specific DMA mmap(2)'ing functions.
 */
paddr_t
_bus_dmamem_mmap(bus_dma_tag_t t, bus_dma_segment_t *segs, int nsegs,
        off_t off, int prot, int flags)
{
        int i;

        for (i = 0; i < nsegs; i++) {
#ifdef DIAGNOSTIC
                if (off & PGOFSET)
                        panic("_bus_dmamem_mmap: offset unaligned");
                if (segs[i].ds_addr & PGOFSET)
                        panic("_bus_dmamem_mmap: segment unaligned");
                if (segs[i].ds_len & PGOFSET)
                        panic("_bus_dmamem_mmap: segment size not multiple"
                            " of page size");
#endif  /* DIAGNOSTIC */
                if (off >= segs[i].ds_len) {
                        off -= segs[i].ds_len;
                        continue;
                }

                return (btop((u_long)segs[i].ds_addr + off));
        }

        /* Page not found. */
        return (-1);
}

/**********************************************************************
 * DMA utility functions
 **********************************************************************/

/*
 * Utility function to load a linear buffer.  lastaddrp holds state
 * between invocations (for multiple-buffer loads).  segp contains
 * the starting segment on entrance, and the ending segment on exit.
 * first indicates if this is the first invocation of this function.
 */
int
_bus_dmamap_load_buffer(bus_dma_tag_t t, bus_dmamap_t map, void *buf,
        bus_size_t buflen, struct vmspace *vm, int flags, vaddr_t *lastaddrp,
        int *segp, bool first)
{
        bus_size_t sgsize;
        bus_addr_t curaddr, lastaddr, baddr, bmask;
        vaddr_t vaddr = (vaddr_t)buf;
        int seg;
        pmap_t pmap;

#ifdef DEBUG_DMA
        printf("_bus_dmamap_load_buffer(buf=%p, len=%lx, flags=%d, 1st=%d)\n",
            buf, buflen, flags, first);
#endif  /* DEBUG_DMA */

        pmap = vm_map_pmap(&vm->vm_map);

        lastaddr = *lastaddrp;
        bmask  = ~(map->_dm_boundary - 1);

        for (seg = *segp; buflen > 0; ) {
                /*
                 * Get the physical address for this segment.
                 */
                (void) pmap_extract(pmap, (vaddr_t)vaddr, &curaddr);

#if 0
                /*
                 * Make sure we're in an allowed DMA range.
                 */
                if (t->_ranges != NULL &&
                    _bus_dma_inrange(t->_ranges, t->_nranges, curaddr) == 0)
                        return (EINVAL);
#endif

                /*
                 * Compute the segment size, and adjust counts.
                 */
                sgsize = PAGE_SIZE - ((u_long)vaddr & PGOFSET);
                if (buflen < sgsize)
                        sgsize = buflen;

                /*
                 * Make sure we don't cross any boundaries.
                 */
                if (map->_dm_boundary > 0) {
                        baddr = (curaddr + map->_dm_boundary) & bmask;
                        if (sgsize > (baddr - curaddr))
                                sgsize = (baddr - curaddr);
                }

                /*
                 * Insert chunk into a segment, coalescing with
                 * previous segment if possible.
                 */
                if (first) {
                        map->dm_segs[seg].ds_addr = curaddr;
                        map->dm_segs[seg].ds_len = sgsize;
                        first = false;
                } else {
                        if (curaddr == lastaddr &&
                            (map->dm_segs[seg].ds_len + sgsize) <=
                             map->dm_maxsegsz &&
                            (map->_dm_boundary == 0 ||
                             (map->dm_segs[seg].ds_addr & bmask) ==
                             (curaddr & bmask)))
                                map->dm_segs[seg].ds_len += sgsize;
                        else {
                                if (++seg >= map->_dm_segcnt)
                                        break;
                                map->dm_segs[seg].ds_addr = curaddr;
                                map->dm_segs[seg].ds_len = sgsize;
                        }
                }

                lastaddr = curaddr + sgsize;
                vaddr += sgsize;
                buflen -= sgsize;
        }

        *segp = seg;
        *lastaddrp = lastaddr;

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

/*
 * Check to see if the specified page is in an allowed DMA range.
 */
int
_bus_dma_inrange(bus_dma_segment_t *ranges, int nranges, bus_addr_t curaddr)
{
        bus_dma_segment_t *ds;
        int i;

        for (i = 0, ds = ranges; i < nranges; i++, ds++) {
                if (curaddr >= ds->ds_addr &&
                    round_page(curaddr) <= (ds->ds_addr + ds->ds_len))
                        return (1);
        }

        return (0);
}

/*
 * Allocate physical memory from the given physical address range.
 * Called by DMA-safe memory allocation methods.
 */
int
_bus_dmamem_alloc_range(bus_dma_tag_t t, bus_size_t size, bus_size_t alignment,
        bus_size_t boundary, bus_dma_segment_t *segs, int nsegs, int *rsegs,
        int flags, vaddr_t low, vaddr_t high)
{
        vaddr_t curaddr, lastaddr;
        struct vm_page *m;
        struct pglist mlist;
        int curseg, error;

#ifdef DEBUG_DMA
        printf("alloc_range: t=%p size=%lx align=%lx boundary=%lx segs=%p nsegs=%x rsegs=%p flags=%x lo=%lx hi=%lx\n",
            t, size, alignment, boundary, segs, nsegs, rsegs, flags, low, high);
#endif  /* DEBUG_DMA */

        /* Always round the size. */
        size = round_page(size);

        /*
         * Allocate pages from the VM system.
         */
        error = uvm_pglistalloc(size, low, high, alignment, boundary,
            &mlist, nsegs, (flags & BUS_DMA_NOWAIT) == 0);
        if (error)
                return (error);

        /*
         * Compute the location, size, and number of segments actually
         * returned by the VM code.
         */
        m = mlist.tqh_first;
        curseg = 0;
        lastaddr = segs[curseg].ds_addr = VM_PAGE_TO_PHYS(m);
        segs[curseg].ds_len = PAGE_SIZE;
#ifdef DEBUG_DMA
                printf("alloc: page %lx\n", lastaddr);
#endif  /* DEBUG_DMA */
        m = m->pageq.queue.tqe_next;

        for (; m != NULL; m = m->pageq.queue.tqe_next) {
                curaddr = VM_PAGE_TO_PHYS(m);
#ifdef DIAGNOSTIC
                if (curaddr < low || curaddr >= high) {
                        printf("uvm_pglistalloc returned non-sensical"
                            " address 0x%lx\n", curaddr);
                        panic("_bus_dmamem_alloc_range");
                }
#endif  /* DIAGNOSTIC */
#ifdef DEBUG_DMA
                printf("alloc: page %lx\n", curaddr);
#endif  /* DEBUG_DMA */
                if (curaddr == (lastaddr + PAGE_SIZE))
                        segs[curseg].ds_len += PAGE_SIZE;
                else {
                        curseg++;
                        segs[curseg].ds_addr = curaddr;
                        segs[curseg].ds_len = PAGE_SIZE;
                }
                lastaddr = curaddr;
        }

        *rsegs = curseg + 1;

        return (0);
}

/*
 * "generic" DMA struct, nothing special.
 */
struct vax_bus_dma_tag vax_bus_dma_tag = {
        ._dmamap_create         = _bus_dmamap_create,
        ._dmamap_destroy        = _bus_dmamap_destroy,
        ._dmamap_load           = _bus_dmamap_load,
        ._dmamap_load_mbuf      = _bus_dmamap_load_mbuf,
        ._dmamap_load_uio       = _bus_dmamap_load_uio,
        ._dmamap_load_raw       = _bus_dmamap_load_raw,
        ._dmamap_unload         = _bus_dmamap_unload,
        ._dmamap_sync           = _bus_dmamap_sync,
        ._dmamem_alloc          = _bus_dmamem_alloc,
        ._dmamem_free           = _bus_dmamem_free,
        ._dmamem_map            = _bus_dmamem_map,
        ._dmamem_unmap          = _bus_dmamem_unmap,
        ._dmamem_mmap           = _bus_dmamem_mmap,
};