/*      $NetBSD: bus_dma.c,v 1.5 2020/11/21 16:21:24 thorpej Exp $      */

/*
 * Copyright (c) 2005 NONAKA Kimihiro <nonaka@netbsd.org>
 * 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.
 * 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 AUTHOR ``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 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.
 */

#include <sys/cdefs.h>
__KERNEL_RCSID(0, "$NetBSD: bus_dma.c,v 1.5 2020/11/21 16:21:24 thorpej Exp $");

#include <sys/param.h>
#include <sys/systm.h>
#include <sys/kernel.h>
#include <sys/device.h>
#include <sys/kmem.h>
#include <sys/mbuf.h>
#define _EVBSH3_BUS_DMA_PRIVATE
#include <sys/bus.h>

#include <uvm/uvm.h>

#include <sh3/cache.h>

#include <machine/autoconf.h>

#if defined(DEBUG) && defined(BUSDMA_DEBUG)
int busdma_debug = 0;
#define DPRINTF(a)      if (busdma_debug) printf a
#else
#define DPRINTF(a)
#endif

struct _bus_dma_tag evbsh3_bus_dma = {
        ._cookie = NULL,

        ._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,
};

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

/*
 * Create a DMA map.
 */
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)
{
        bus_dmamap_t map;
        void *mapstore;

        DPRINTF(("%s: t = %p, size = %ld, nsegments = %d, maxsegsz = %ld,"
                 " boundary = %ld, flags = %x\n",
                 __func__, t, size, nsegments, maxsegsz, boundary, flags));

        /*
         * 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.  bus_dmamap_t includes one
         * bus_dma_segment_t already, hence the (nsegments - 1).
         *
         * Note that we don't preserve WAITOK and NOWAIT flags.
         * Preservation of ALLOCNOW notifies others that we've
         * reserved these resources, and they are not to be freed.
         */
        mapstore = kmem_zalloc(_bus_dmamap_mapsize(nsegments),
                          (flags & BUS_DMA_NOWAIT) ? KM_NOSLEEP : KM_SLEEP);
        if (mapstore == NULL)
                return ENOMEM;

        DPRINTF(("%s: dmamp = %p\n", __func__, mapstore));

        map = (bus_dmamap_t)mapstore;
        map->_dm_size = size;
        map->_dm_segcnt = nsegments;
        map->_dm_maxsegsz = maxsegsz;
        map->_dm_boundary = boundary;
        map->_dm_flags = flags & ~(BUS_DMA_WAITOK | BUS_DMA_NOWAIT);

        map->dm_mapsize = 0;            /* no valid mappings */
        map->dm_nsegs = 0;

        *dmamp = map;
        return 0;
}

/*
 * Destroy a DMA map.
 */
void
_bus_dmamap_destroy(bus_dma_tag_t t, bus_dmamap_t map)
{

        DPRINTF(("%s: t = %p, map = %p\n", __func__, t, map));

        kmem_free(map, _bus_dmamap_mapsize(map->_dm_segcnt));
}

static inline int
_bus_dmamap_load_paddr(bus_dma_tag_t t, bus_dmamap_t map,
    paddr_t paddr, vaddr_t vaddr, int size, int *segp, paddr_t *lastaddrp,
    int first)
{
        bus_dma_segment_t * const segs = map->dm_segs;
        bus_addr_t bmask = ~(map->_dm_boundary - 1);
        bus_addr_t lastaddr;
        int nseg;
        int sgsize;

        nseg = *segp;
        lastaddr = *lastaddrp;

        DPRINTF(("%s: t = %p, map = %p, paddr = 0x%08lx,"
                 " vaddr = 0x%08lx, size = %d\n",
                 __func__, t, map, paddr, vaddr, size));
        DPRINTF(("%s: nseg = %d, bmask = 0x%08lx, lastaddr = 0x%08lx\n",
                 __func__, nseg, bmask, lastaddr));

        do {
                sgsize = size;

                /*
                 * Make sure we don't cross any boundaries.
                 */
                if (map->_dm_boundary > 0) {
                        bus_addr_t baddr; /* next boundary address */

                        baddr = (paddr + map->_dm_boundary) & bmask;
                        if (sgsize > (baddr - paddr))
                                sgsize = (baddr - paddr);
                }

                DPRINTF(("%s: sgsize = %d\n", __func__, sgsize));

                /*
                 * Insert chunk coalescing with previous segment if possible.
                 */
                if (first) {
                        DPRINTF(("%s: first\n", __func__));
                        first = 0;

                        segs[nseg].ds_addr = SH3_PHYS_TO_P2SEG(paddr);
                        segs[nseg].ds_len = sgsize;
                        segs[nseg]._ds_vaddr = vaddr;
                }
                else if ((paddr == lastaddr)
                         && (segs[nseg].ds_len + sgsize <= map->_dm_maxsegsz)
                         && (map->_dm_boundary == 0 ||
                             (segs[nseg].ds_addr & bmask) == (paddr & bmask)))
                {
                        DPRINTF(("%s: coalesce\n", __func__));

                        segs[nseg].ds_len += sgsize;
                }
                else {
                        DPRINTF(("%s: new\n", __func__));

                        ++nseg;
                        if (nseg >= map->_dm_segcnt)
                                break;

                        segs[nseg].ds_addr = SH3_PHYS_TO_P2SEG(paddr);
                        segs[nseg].ds_len = sgsize;
                        segs[nseg]._ds_vaddr = vaddr;
                }

                paddr += sgsize;
                vaddr += sgsize;
                size -= sgsize;
                lastaddr = paddr;

                DPRINTF(("%s: lastaddr = 0x%08lx, paddr = 0x%08lx,"
                         " vaddr = 0x%08lx, size = %d\n",
                         __func__, lastaddr, paddr, vaddr, size));
        } while (size > 0);

        DPRINTF(("%s: nseg = %d\n", __func__, nseg));

        *segp = nseg;
        *lastaddrp = lastaddr;

        if (size != 0) {
                /*
                 * It didn't fit.  If there is a chained window, we
                 * will automatically fall back to it.
                 */
                return (EFBIG);         /* XXX better return value here? */
        }

        return (0);
}

static inline int
_bus_bus_dmamap_load_buffer(bus_dma_tag_t t, bus_dmamap_t map, void *buf,
    bus_size_t buflen, struct proc *p, int flags, int *segp)
{
        bus_size_t sgsize;
        bus_addr_t curaddr;
        bus_size_t len;
        paddr_t lastaddr;
        vaddr_t vaddr = (vaddr_t)buf;
        pmap_t pmap;
        int first;
        int error;

        DPRINTF(("%s: t = %p, map = %p, buf = %p, buflen = %ld,"
                 " p = %p, flags = %x\n",
                 __func__, t, map, buf, buflen, p, flags));

        if (p != NULL)
                pmap = p->p_vmspace->vm_map.pmap;
        else
                pmap = pmap_kernel();

        first = 1;
        lastaddr = 0;

        len = buflen;
        while (len > 0) {
                bool mapped;

                mapped = pmap_extract(pmap, vaddr, &curaddr);
                if (!mapped)
                        return EFAULT;

                sgsize = PAGE_SIZE - (vaddr & PGOFSET);
                if (len < sgsize)
                        sgsize = len;

                error = _bus_dmamap_load_paddr(t, map, curaddr, vaddr, sgsize,
                                               segp, &lastaddr, first);
                if (error)
                        return error;

                vaddr += sgsize;
                len -= sgsize;
                first = 0;
        }

        return 0;
}

/*
 * Load a DMA map with a linear buffer.
 */
int
_bus_dmamap_load(bus_dma_tag_t t, bus_dmamap_t map, void *buf,
    bus_size_t buflen, struct proc *p, int flags)
{
        bus_addr_t addr = (bus_addr_t)buf;
        paddr_t lastaddr;
        int seg;
        int first;
        int error;

        DPRINTF(("%s: t = %p, map = %p, buf = %p, buflen = %ld,"
                 " p = %p, flags = %x\n",
                 __func__, t, map, buf, buflen, p, flags));

        /* make sure that on error condition we return "no valid mappings" */
        map->dm_mapsize = 0;
        map->dm_nsegs = 0;

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

        error = 0;
        seg = 0;

        if (SH3_P1SEG_BASE <= addr && addr + buflen <= SH3_P2SEG_END) {
                bus_addr_t curaddr;
                bus_size_t sgsize;
                bus_size_t len = buflen;

                DPRINTF(("%s: P[12]SEG (0x%08lx)\n", __func__, addr));

                first = 1;
                lastaddr = 0;

                while (len > 0) {
                        curaddr = SH3_P1SEG_TO_PHYS(addr);

                        sgsize = PAGE_SIZE - ((u_long)addr & PGOFSET);
                        if (len < sgsize)
                                sgsize = len;

                        error = _bus_dmamap_load_paddr(t, map,
                                                       curaddr, addr, sgsize,
                                                       &seg, &lastaddr, first);
                        if (error)
                                break;

                        addr += sgsize;
                        len -= sgsize;
                        first = 0;
                }
        }
        else {
                error = _bus_bus_dmamap_load_buffer(t, map, buf, buflen,
                                                    p, flags, &seg);
        }

        if (error)
                return (error);

        map->dm_nsegs = seg + 1;
        map->dm_mapsize = buflen;
        return 0;
}

/*
 * 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)
{
        struct mbuf *m;
        paddr_t lastaddr;
        int seg;
        int first;
        int error;

        DPRINTF(("%s: t = %p, map = %p, m0 = %p, flags = %x\n",
                 __func__, t, map, m0, flags));

        /* make sure that on error condition we return "no valid mappings" */
        map->dm_nsegs = 0;
        map->dm_mapsize = 0;

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

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

        seg = 0;
        first = 1;
        lastaddr = 0;

        for (m = m0; m != NULL; m = m->m_next) {
                paddr_t paddr;
                vaddr_t vaddr;
                int size;

                if (m->m_len == 0)
                        continue;

                vaddr = (vaddr_t)m->m_data;
                size = m->m_len;

                if (SH3_P1SEG_BASE <= vaddr && vaddr < SH3_P3SEG_BASE) {
                        paddr = (paddr_t)(PMAP_UNMAP_POOLPAGE(vaddr));
                        error = _bus_dmamap_load_paddr(t, map,
                                                       paddr, vaddr, size,
                                                       &seg, &lastaddr, first);
                        if (error)
                                return error;
                        first = 0;
                }
                else {
                        /* XXX: stolen from load_buffer, need to refactor */
                        while (size > 0) {
                                bus_size_t sgsize;
                                bool mapped;

                                mapped = pmap_extract(pmap_kernel(), vaddr,
                                                      &paddr);
                                if (!mapped)
                                        return EFAULT;

                                sgsize = PAGE_SIZE - (vaddr & PGOFSET);
                                if (size < sgsize)
                                        sgsize = size;

                                error = _bus_dmamap_load_paddr(t, map,
                                                paddr, vaddr, sgsize,
                                                &seg, &lastaddr, first);
                                if (error)
                                        return error;

                                vaddr += sgsize;
                                size -= sgsize;
                                first = 0;
                        }

                }
        }

        map->dm_nsegs = seg + 1;
        map->dm_mapsize = m0->m_pkthdr.len;
        return 0;
}

/*
 * 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)
{

        panic("_bus_dmamap_load_uio: not implemented");
}

/*
 * 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");
}

/*
 * Unload a DMA map.
 */
void
_bus_dmamap_unload(bus_dma_tag_t t, bus_dmamap_t map)
{

        DPRINTF(("%s: t = %p, map = %p\n", __func__, t, map));

        map->dm_nsegs = 0;
        map->dm_mapsize = 0;
}

/*
 * Synchronize a DMA map.
 */
void
_bus_dmamap_sync(bus_dma_tag_t t, bus_dmamap_t map, bus_addr_t offset,
    bus_size_t len, int ops)
{
        bus_size_t minlen;
        bus_addr_t addr, naddr;
        int i;

        DPRINTF(("%s: t = %p, map = %p, offset = %ld, len = %ld, ops = %x\n",
                 __func__, t, map, offset, len, ops));

#ifdef DIAGNOSTIC
        if ((ops & (BUS_DMASYNC_PREREAD|BUS_DMASYNC_PREWRITE)) != 0 &&
            (ops & (BUS_DMASYNC_POSTREAD|BUS_DMASYNC_POSTWRITE)) != 0)
                panic("_bus_dmamap_sync: mix PRE and POST");

        if (offset >= map->dm_mapsize)
                panic("_bus_dmamap_sync: bad offset");
        if ((offset + len) > map->dm_mapsize)
                panic("_bus_dmamap_sync: bad length");
#endif

        if (!sh_cache_enable_dcache) {
                /* Nothing to do */
                DPRINTF(("%s: disabled D-Cache\n", __func__));
                return;
        }

        for (i = 0; i < map->dm_nsegs && len != 0; i++) {
                /* Find the beginning segment. */
                if (offset >= map->dm_segs[i].ds_len) {
                        offset -= map->dm_segs[i].ds_len;
                        continue;
                }

                /*
                 * Now at the first segment to sync; nail
                 * each segment until we have exhausted the
                 * length.
                 */
                minlen = len < map->dm_segs[i].ds_len - offset ?
                    len : map->dm_segs[i].ds_len - offset;

                addr = map->dm_segs[i]._ds_vaddr;
                naddr = addr + offset;

                if ((naddr >= SH3_P2SEG_BASE)
                 && (naddr + minlen <= SH3_P2SEG_END)) {
                        DPRINTF(("%s: P2SEG (0x%08lx)\n", __func__, naddr));
                        offset = 0;
                        len -= minlen;
                        continue;
                }

                DPRINTF(("%s: flushing segment %d "
                         "(0x%lx+%lx, 0x%lx+0x%lx) (remain = %ld)\n",
                         __func__, i,
                         addr, offset, addr, offset + minlen - 1, len));

                switch (ops) {
                case BUS_DMASYNC_PREREAD|BUS_DMASYNC_PREWRITE:
                        if (SH_HAS_WRITEBACK_CACHE)
                                sh_dcache_wbinv_range(naddr, minlen);
                        else
                                sh_dcache_inv_range(naddr, minlen);
                        break;

                case BUS_DMASYNC_PREREAD:
                        if (SH_HAS_WRITEBACK_CACHE &&
                            ((naddr | minlen) & (sh_cache_line_size - 1)) != 0)
                                sh_dcache_wbinv_range(naddr, minlen);
                        else
                                sh_dcache_inv_range(naddr, minlen);
                        break;

                case BUS_DMASYNC_PREWRITE:
                        if (SH_HAS_WRITEBACK_CACHE)
                                sh_dcache_wb_range(naddr, minlen);
                        break;
                }
                offset = 0;
                len -= minlen;
        }
}

/*
 * Allocate memory safe for DMA.
 */
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)
{
        extern paddr_t avail_start, avail_end;  /* from pmap.c */
        struct pglist mlist;
        paddr_t curaddr, lastaddr;
        struct vm_page *m;
        int curseg, error;

        DPRINTF(("%s: t = %p, size = %ld, alignment = %ld, boundary = %ld,"
                 " segs = %p, nsegs = %d, rsegs = %p, flags = %x\n",
                 __func__, t, size, alignment, boundary,
                 segs, nsegs, rsegs, flags));
        DPRINTF(("%s: avail_start = 0x%08lx, avail_end = 0x%08lx\n",
                 __func__, avail_start, avail_end));

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

        /*
         * Allocate the pages from the VM system.
         */
        error = uvm_pglistalloc(size, avail_start, avail_end - PAGE_SIZE,
            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;

        DPRINTF(("%s: m = %p, lastaddr = 0x%08lx\n", __func__, m, lastaddr));

        while ((m = TAILQ_NEXT(m, pageq.queue)) != NULL) {
                curaddr = VM_PAGE_TO_PHYS(m);
                DPRINTF(("%s: m = %p, curaddr = 0x%08lx, lastaddr = 0x%08lx\n",
                         __func__, m, curaddr, lastaddr));

                if (curaddr == (lastaddr + PAGE_SIZE)) {
                        segs[curseg].ds_len += PAGE_SIZE;
                } else {
                        DPRINTF(("%s: new segment\n", __func__));
                        curseg++;
                        segs[curseg].ds_addr = curaddr;
                        segs[curseg].ds_len = PAGE_SIZE;
                }
                lastaddr = curaddr;
        }

        *rsegs = curseg + 1;

        DPRINTF(("%s: curseg = %d, *rsegs = %d\n", __func__, curseg, *rsegs));

        return (0);
}

/*
 * 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;

        DPRINTF(("%s: t = %p, segs = %p, nsegs = %d\n",
                 __func__, t, segs, nsegs));

        /*
         * Build a list of pages to free back to the VM system.
         */
        TAILQ_INIT(&mlist);
        for (curseg = 0; curseg < nsegs; curseg++) {
                DPRINTF(("%s: segs[%d]: ds_addr = 0x%08lx, ds_len = %ld\n",
                         __func__, curseg,
                         segs[curseg].ds_addr, segs[curseg].ds_len));

                for (addr = segs[curseg].ds_addr;
                     addr < (segs[curseg].ds_addr + segs[curseg].ds_len);
                     addr += PAGE_SIZE)
                {
                        m = PHYS_TO_VM_PAGE(addr);
                        DPRINTF(("%s: m = %p\n", __func__, m));
                        TAILQ_INSERT_TAIL(&mlist, m, pageq.queue);
                }
        }

        uvm_pglistfree(&mlist);
}


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, topva;
        bus_addr_t addr;
        int curseg;

        DPRINTF(("%s: t = %p, segs = %p, nsegs = %d, size = %d,"
                 " kvap = %p, flags = %x\n",
                 __func__, t, segs, nsegs, size, kvap, flags));

        /*
         * If we're mapping only a single segment, use direct-mapped
         * va, to avoid thrashing the TLB.
         */
        if (nsegs == 1) {
                if (flags & BUS_DMA_COHERENT)
                        *kvap = (void *)SH3_PHYS_TO_P2SEG(segs[0].ds_addr);
                else
                        *kvap = (void *)SH3_PHYS_TO_P1SEG(segs[0].ds_addr);

                DPRINTF(("%s: addr = 0x%08lx, kva = %p\n",
                         __func__, segs[0].ds_addr, *kvap));
                return 0;
        }


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

        va = uvm_km_alloc(kernel_map, size, 0, UVM_KMF_VAONLY
                          | ((flags & BUS_DMA_NOWAIT) ? UVM_KMF_NOWAIT : 0));
        if (va == 0)
                return (ENOMEM);
        topva = va;

        for (curseg = 0; curseg < nsegs; curseg++) {
                DPRINTF(("%s: segs[%d]: ds_addr = 0x%08lx, ds_len = %ld\n",
                         __func__, curseg,
                         segs[curseg].ds_addr, segs[curseg].ds_len));

                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 (__predict_false(size == 0))
                                panic("_bus_dmamem_map: size botch");

                        pmap_kenter_pa(va, addr,
                                       VM_PROT_READ | VM_PROT_WRITE, 0);
                }
        }

        pmap_update(pmap_kernel());
        *kvap = (void *)topva;
        return (0);
}

void
_bus_dmamem_unmap(bus_dma_tag_t t, void *kva, size_t size)
{
        vaddr_t vaddr = (vaddr_t)kva;

        DPRINTF(("%s: t = %p, kva = %p, size = %d\n",
                 __func__, t, kva, size));

#ifdef DIAGNOSTIC
        if (vaddr & PAGE_MASK)
                panic("_bus_dmamem_unmap");
#endif

        /* nothing to do if we mapped it via P1SEG or P2SEG */
        if (SH3_P1SEG_BASE <= vaddr && vaddr <= SH3_P2SEG_END)
                return;

        size = round_page(size);
        pmap_kremove(vaddr, size);
        pmap_update(pmap_kernel());
        uvm_km_free(kernel_map, vaddr, size, UVM_KMF_VAONLY);
}

paddr_t
_bus_dmamem_mmap(bus_dma_tag_t t, bus_dma_segment_t *segs, int nsegs,
    off_t off, int prot, int flags)
{

        /* Not implemented. */
        return (paddr_t)(-1);
}