OpenGrok

/*	$NetBSD: bus.c,v 1.38 2022/07/26 20:08:56 andvar Exp $	*/

/*
 * Copyright (c) 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.
 */

#include <sys/cdefs.h>
__KERNEL_RCSID(0, "$NetBSD: bus.c,v 1.38 2022/07/26 20:08:56 andvar Exp $");

#include <sys/param.h>
#include <sys/systm.h>
#include <sys/kernel.h>
#include <sys/device.h>
#include <sys/kmem.h>
#include <sys/proc.h>
#include <sys/mbuf.h>

#define _NEWSMIPS_BUS_DMA_PRIVATE
#include <machine/bus.h>
#include <machine/cpu.h>

#include <dev/bus_dma/bus_dmamem_common.h>

#include <uvm/uvm_extern.h>

#include <mips/cache.h>

static int	_bus_dmamap_load_buffer(bus_dmamap_t, void *, bus_size_t,
				struct vmspace *, int, vaddr_t *, int *, int);

struct newsmips_bus_dma_tag newsmips_default_bus_dma_tag = {
	_bus_dmamap_create,
	_bus_dmamap_destroy,
	_bus_dmamap_load,
	_bus_dmamap_load_mbuf,
	_bus_dmamap_load_uio,
	_bus_dmamap_load_raw,
	_bus_dmamap_unload,
	NULL,
	_bus_dmamem_alloc,
	_bus_dmamem_free,
	_bus_dmamem_map,
	_bus_dmamem_unmap,
	_bus_dmamem_mmap,
};

void
newsmips_bus_dma_init(void)
{

#ifdef MIPS1
	if (CPUISMIPS3 == 0)
		newsmips_default_bus_dma_tag._dmamap_sync =
		    _bus_dmamap_sync_r3k;
#endif
#ifdef MIPS3
	if (CPUISMIPS3)
		newsmips_default_bus_dma_tag._dmamap_sync =
		    _bus_dmamap_sync_r4k;
#endif
}

int
bus_space_map(bus_space_tag_t t, bus_addr_t bpa, bus_size_t size, int flags,
    bus_space_handle_t *bshp)
{
	int cacheable = flags & BUS_SPACE_MAP_CACHEABLE;

	if (cacheable)
		*bshp = MIPS_PHYS_TO_KSEG0(bpa);
	else
		*bshp = MIPS_PHYS_TO_KSEG1(bpa);

	return 0;
}

int
bus_space_alloc(bus_space_tag_t t, bus_addr_t rstart, bus_addr_t rend,
    bus_size_t size, bus_size_t alignment, bus_size_t boundary, int flags,
    bus_addr_t *bpap, bus_space_handle_t *bshp)
{

	panic("bus_space_alloc: not implemented");
}

void
bus_space_free(bus_space_tag_t t, bus_space_handle_t bsh, bus_size_t size)
{

	panic("bus_space_free: not implemented");
}

void
bus_space_unmap(bus_space_tag_t t, bus_space_handle_t bsh, bus_size_t size)
{

	return;
}

int
bus_space_subregion(bus_space_tag_t t, bus_space_handle_t bsh,
    bus_size_t offset, bus_size_t size, bus_space_handle_t *nbshp)
{

	*nbshp = bsh + offset;
	return 0;
}

static size_t
_bus_dmamap_mapsize(int const nsegments)
{
	KASSERT(nsegments > 0);
	return sizeof(struct newsmips_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 newsmips_bus_dmamap *map;
	void *mapstore;

	/*
	 * 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 newsmips_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_vmspace = NULL;
	map->dm_maxsegsz = maxsegsz;
	map->dm_mapsize = 0;		/* no valid mappings */
	map->dm_nsegs = 0;

	*dmamp = map;
	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)
{

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

extern	paddr_t kvtophys(vaddr_t);		/* XXX */

/*
 * 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_dmamap_t map, void *buf, bus_size_t buflen,
    struct vmspace *vm, int flags, vaddr_t *lastaddrp, int *segp, int first)
{
	bus_size_t sgsize;
	bus_addr_t curaddr, lastaddr, baddr, bmask;
	vaddr_t vaddr = (vaddr_t)buf;
	paddr_t pa;
	size_t seg;

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

	for (seg = *segp; buflen > 0 ; ) {
		/*
		 * Get the physical address for this segment.
		 */
		if (!VMSPACE_IS_KERNEL_P(vm))
			(void) pmap_extract(vm_map_pmap(&vm->vm_map),
			    vaddr, &pa);
		else
			pa = kvtophys(vaddr);
		curaddr = pa;

		/*
		 * 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
		 * the previous segment if possible.
		 */
		if (first) {
			map->dm_segs[seg].ds_addr = curaddr;
			map->dm_segs[seg].ds_len = sgsize;
			map->dm_segs[seg]._ds_vaddr = vaddr;
			first = 0;
		} 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;
				map->dm_segs[seg]._ds_vaddr = vaddr;
			}
		}

		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;
}

/*
 * Common function for loading a direct-mapped 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)
{
	vaddr_t lastaddr;
	int seg, error;
	struct vmspace *vm;

	/*
	 * 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(map, buf, buflen,
	    vm, flags, &lastaddr, &seg, 1);
	if (error == 0) {
		map->dm_mapsize = buflen;
		map->dm_nsegs = seg + 1;
		map->_dm_vmspace = vm;

		/*
		 * For linear buffers, we support marking the mapping
		 * as COHERENT.
		 *
		 * XXX Check TLB entries for cache-inhibit bits?
		 */
		if (buf >= (void *)MIPS_KSEG1_START &&
		    buf < (void *)MIPS_KSEG2_START)
			map->_dm_flags |= NEWSMIPS_DMAMAP_COHERENT;
	}
	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;
	int seg, error, first;
	struct mbuf *m;

	/*
	 * 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

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

	first = 1;
	seg = 0;
	error = 0;
	for (m = m0; m != NULL && error == 0; m = m->m_next) {
		if (m->m_len == 0)
			continue;
		error = _bus_dmamap_load_buffer(map, m->m_data, m->m_len,
		    vmspace_kernel(), flags, &lastaddr, &seg, first);
		first = 0;
	}
	if (error == 0) {
		map->dm_mapsize = m0->m_pkthdr.len;
		map->dm_nsegs = seg + 1;
		map->_dm_vmspace = vmspace_kernel();	/* always kernel */
	}
	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;
	int seg, i, error, 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 = 1;
	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(map, addr, minlen,
		    uio->uio_vmspace, flags, &lastaddr, &seg, first);
		first = 0;

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

/*
 * Like _bus_dmamap_load(), but for raw memory.
 */
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
 * chipset-specific DMA map unload functions.
 */
void
_bus_dmamap_unload(bus_dma_tag_t t, bus_dmamap_t map)
{

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

#ifdef MIPS1
/*
 * Common function for DMA map synchronization.  May be called
 * by chipset-specific DMA map synchronization functions.
 *
 * This is the R3000 version.
 */
void
_bus_dmamap_sync_r3k(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;
	int i;

	/*
	 * Mixing PRE and POST operations is not allowed.
	 */
	if ((ops & (BUS_DMASYNC_PREREAD|BUS_DMASYNC_PREWRITE)) != 0 &&
	    (ops & (BUS_DMASYNC_POSTREAD|BUS_DMASYNC_POSTWRITE)) != 0)
		panic("_bus_dmamap_sync_r3k: mix PRE and POST");

#ifdef DIAGNOSTIC
	if (offset >= map->dm_mapsize)
		panic("_bus_dmamap_sync_r3k: bad offset %lu (map size is %lu)",
		      offset, map->dm_mapsize);
	if (len == 0 || (offset + len) > map->dm_mapsize)
		panic("_bus_dmamap_sync_r3k: bad length");
#endif

	/*
	 * The R3000 cache is write-though.  Therefore, we only need
	 * to drain the write buffer on PREWRITE.  The cache is not
	 * coherent, however, so we need to invalidate the data cache
	 * on PREREAD (should we do it POSTREAD instead?).
	 *
	 * POSTWRITE (and POSTREAD, currently) are noops.
	 */

	if (ops & BUS_DMASYNC_PREWRITE) {
		/*
		 * Flush the write buffer.
		 */
		wbflush();
	}

	/*
	 * If we're not doing PREREAD, nothing more to do.
	 */
	if ((ops & BUS_DMASYNC_PREREAD) == 0)
		return;

	/*
	 * No cache invalidation is necessary if the DMA map covers
	 * COHERENT DMA-safe memory (which is mapped un-cached).
	 */
	if (map->_dm_flags & NEWSMIPS_DMAMAP_COHERENT)
		return;

	/*
	 * If we are going to hit something as large or larger
	 * than the entire data cache, just nail the whole thing.
	 *
	 * NOTE: Even though this is `wbinv_all', since the cache is
	 * write-though, it just invalidates it.
	 */
	if (len >= mips_cache_info.mci_pdcache_size) {
		mips_dcache_wbinv_all();
		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_addr;

#ifdef BUS_DMA_DEBUG
		printf("bus_dmamap_sync_r3k: flushing segment %d "
		    "(0x%lx..0x%lx) ...", i, addr + offset,
		    addr + offset + minlen - 1);
#endif
		mips_dcache_inv_range(
		    MIPS_PHYS_TO_KSEG0(addr + offset), minlen);
#ifdef BUS_DMA_DEBUG
		printf("\n");
#endif
		offset = 0;
		len -= minlen;
	}
}
#endif /* MIPS1 */

#ifdef MIPS3
/*
 * Common function for DMA map synchronization.  May be called
 * by chipset-specific DMA map synchronization functions.
 *
 * This is the R4000 version.
 */
void
_bus_dmamap_sync_r4k(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;
	int i, useindex;

	/*
	 * Mixing PRE and POST operations is not allowed.
	 */
	if ((ops & (BUS_DMASYNC_PREREAD|BUS_DMASYNC_PREWRITE)) != 0 &&
	    (ops & (BUS_DMASYNC_POSTREAD|BUS_DMASYNC_POSTWRITE)) != 0)
		panic("_bus_dmamap_sync_r4k: mix PRE and POST");

#ifdef DIAGNOSTIC
	if (offset >= map->dm_mapsize)
		panic("_bus_dmamap_sync_r4k: bad offset %lu (map size is %lu)",
		      offset, map->dm_mapsize);
	if (len == 0 || (offset + len) > map->dm_mapsize)
		panic("_bus_dmamap_sync_r4k: bad length");
#endif

	/*
	 * The R4000 cache is virtually-indexed, write-back.  This means
	 * we need to do the following things:
	 *
	 *	PREREAD -- Invalidate D-cache.  Note we might have
	 *	to also write-back here if we have to use an Index
	 *	op, or if the buffer start/end is not cache-line aligned.
	 *
	 *	PREWRITE -- Write-back the D-cache.  If we have to use
	 *	an Index op, we also have to invalidate.  Note that if
	 *	we are doing PREREAD|PREWRITE, we can collapse everything
	 *	into a single op.
	 *
	 *	POSTREAD -- Nothing.
	 *
	 *	POSTWRITE -- Nothing.
	 */

	/*
	 * Flush the write buffer.
	 * XXX Is this always necessary?
	 */
	wbflush();

	ops &= (BUS_DMASYNC_PREREAD|BUS_DMASYNC_PREWRITE);
	if (ops == 0)
		return;

	/*
	 * If the mapping is of COHERENT DMA-safe memory, no cache
	 * flush is necessary.
	 */
	if (map->_dm_flags & NEWSMIPS_DMAMAP_COHERENT)
		return;

	/*
	 * If the mapping belongs to the kernel, or if it belongs
	 * to the currently-running process (XXX actually, vmspace),
	 * then we can use Hit ops.  Otherwise, Index ops.
	 *
	 * This should be true the vast majority of the time.
	 */
	if (__predict_true(VMSPACE_IS_KERNEL_P(map->_dm_vmspace) ||
	    map->_dm_vmspace == curproc->p_vmspace))
		useindex = 0;
	else
		useindex = 1;

	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;

#ifdef BUS_DMA_DEBUG
		printf("bus_dmamap_sync: flushing segment %d "
		    "(0x%lx..0x%lx) ...", i, addr + offset,
		    addr + offset + minlen - 1);
#endif

		/*
		 * If we are forced to use Index ops, it's always a
		 * Write-back,Invalidate, so just do one test.
		 */
		if (__predict_false(useindex)) {
			mips_dcache_wbinv_range_index(addr + offset, minlen);
#ifdef BUS_DMA_DEBUG
			printf("\n");
#endif
			offset = 0;
			len -= minlen;
			continue;
		}

		switch (ops) {
		case BUS_DMASYNC_PREREAD|BUS_DMASYNC_PREWRITE:
			mips_dcache_wbinv_range(addr + offset, minlen);
			break;

		case BUS_DMASYNC_PREREAD:
#if 1
			mips_dcache_wbinv_range(addr + offset, minlen);
#else
			mips_dcache_inv_range(addr + offset, minlen);
#endif
			break;

		case BUS_DMASYNC_PREWRITE:
			mips_dcache_wb_range(addr + offset, minlen);
			break;
		}
#ifdef BUS_DMA_DEBUG
		printf("\n");
#endif
		offset = 0;
		len -= minlen;
	}
}
#endif /* MIPS3 */

/*
 * 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)
{
	return (_bus_dmamem_alloc_range_common(t, size, alignment, boundary,
	    segs, nsegs, rsegs, flags,
	    pmap_limits.avail_start /*low*/,
	    pmap_limits.avail_end - 1 /*high*/));
}

/*
 * 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)
{

	_bus_dmamem_free_common(t, segs, nsegs);
}

/*
 * 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)
{

	/*
	 * If we're only mapping 1 segment, and the address is lower than
	 * 256MB, use KSEG0 or KSEG1, to avoid TLB thrashing.
	 */
	if (nsegs == 1 && segs[0].ds_addr + segs[0].ds_len <= 0x10000000) {
		if (flags & BUS_DMA_COHERENT)
			*kvap = (void *)MIPS_PHYS_TO_KSEG1(segs[0].ds_addr);
		else
			*kvap = (void *)MIPS_PHYS_TO_KSEG0(segs[0].ds_addr);
		return 0;
	}

	/* XXX BUS_DMA_COHERENT */
	return (_bus_dmamem_map_common(t, segs, nsegs, size, kvap, flags, 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)
{

	/*
	 * Nothing to do if we mapped it with KSEG0 or KSEG1 (i.e.
	 * not in KSEG2).
	 */
	if (kva >= (void *)MIPS_KSEG0_START &&
	    kva < (void *)MIPS_KSEG2_START)
		return;

	_bus_dmamem_unmap_common(t, kva, size);
}

/*
 * 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)
{
	bus_addr_t rv;

	rv = _bus_dmamem_mmap_common(t, segs, nsegs, off, prot, flags);
	if (rv == (bus_addr_t)-1)
		return (-1);

	return (mips_btop((char *)rv));
}