xref: /src/sys/arch/arm/arm32/bus_dma.c

/*	$NetBSD: bus_dma.c,v 1.39 2004/06/19 18:06:00 thorpej 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.
 * 3. All advertising materials mentioning features or use of this software
 *    must display the following acknowledgement:
 *	This product includes software developed by the NetBSD
 *	Foundation, Inc. and its contributors.
 * 4. Neither the name of The NetBSD Foundation nor the names of its
 *    contributors may be used to endorse or promote products derived
 *    from this software without specific prior written permission.
 *
 * 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.
 */

#define _ARM32_BUS_DMA_PRIVATE

#include <sys/cdefs.h>
__KERNEL_RCSID(0, "$NetBSD: bus_dma.c,v 1.39 2004/06/19 18:06:00 thorpej 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/malloc.h>
#include <sys/mbuf.h>
#include <sys/vnode.h>
#include <sys/device.h>

#include <uvm/uvm_extern.h>

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

#include <arm/cpufunc.h>

int	_bus_dmamap_load_buffer(bus_dma_tag_t, bus_dmamap_t, void *,
	    bus_size_t, struct proc *, int, paddr_t *, int *);
struct arm32_dma_range *_bus_dma_inrange(struct arm32_dma_range *,
	    int, bus_addr_t);

/*
 * Check to see if the specified page is in an allowed DMA range.
 */
__inline struct arm32_dma_range *
_bus_dma_inrange(struct arm32_dma_range *ranges, int nranges,
    bus_addr_t curaddr)
{
	struct arm32_dma_range *dr;
	int i;

	for (i = 0, dr = ranges; i < nranges; i++, dr++) {
		if (curaddr >= dr->dr_sysbase &&
		    round_page(curaddr) <= (dr->dr_sysbase + dr->dr_len))
			return (dr);
	}

	return (NULL);
}

/*
 * 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 arm32_bus_dmamap *map;
	void *mapstore;
	size_t mapsize;

#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).
	 */
	mapsize = sizeof(struct arm32_bus_dmamap) +
	    (sizeof(bus_dma_segment_t) * (nsegments - 1));
	if ((mapstore = malloc(mapsize, M_DMAMAP,
	    (flags & BUS_DMA_NOWAIT) ? M_NOWAIT : M_WAITOK)) == NULL)
		return (ENOMEM);

	memset(mapstore, 0, mapsize);
	map = (struct arm32_bus_dmamap *)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_origbuf = NULL;
	map->_dm_buftype = ARM32_BUFTYPE_INVALID;
	map->_dm_proc = NULL;
	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 */

	/*
	 * Explicit unload.
	 */
	map->dm_mapsize = 0;
	map->dm_nsegs = 0;
	map->_dm_origbuf = NULL;
	map->_dm_buftype = ARM32_BUFTYPE_INVALID;
	map->_dm_proc = NULL;

	free(map, M_DMAMAP);
}

/*
 * 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)
{
	paddr_t lastaddr;
	int seg, error;

#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;

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

	/* _bus_dmamap_load_buffer() clears this if we're not... */
	map->_dm_flags |= ARM32_DMAMAP_COHERENT;

	seg = -1;
	error = _bus_dmamap_load_buffer(t, map, buf, buflen, p, flags,
	    &lastaddr, &seg);
	if (error == 0) {
		map->dm_mapsize = buflen;
		map->dm_nsegs = seg + 1;
		map->_dm_origbuf = buf;
		map->_dm_buftype = ARM32_BUFTYPE_LINEAR;
		map->_dm_proc = p;
	}
#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)
{
	struct arm32_dma_range *dr;
	paddr_t lastaddr;
	int seg, error;
	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;

#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);

	/*
	 * Mbuf chains should almost never have coherent (i.e.
	 * un-cached) mappings, so clear that flag now.
	 */
	map->_dm_flags &= ~ARM32_DMAMAP_COHERENT;

	seg = -1;
	error = 0;
	for (m = m0; m != NULL && error == 0; m = m->m_next) {
		if (m->m_len == 0)
			continue;
		/* XXX Could be better about coalescing. */
		/* XXX Doesn't check boundaries. */
		switch (m->m_flags & (M_EXT|M_CLUSTER)) {
		case M_EXT|M_CLUSTER:
			/* XXX KDASSERT */
			KASSERT(m->m_ext.ext_paddr != M_PADDR_INVALID);
			lastaddr = m->m_ext.ext_paddr +
			    (m->m_data - m->m_ext.ext_buf);
 have_addr:
			if (++seg >= map->_dm_segcnt) {
				error = EFBIG;
				break;
			}
			/*
			 * Make sure we're in an allowed DMA range.
			 */
			if (t->_ranges != NULL) {
				/* XXX cache last result? */
				dr = _bus_dma_inrange(t->_ranges, t->_nranges,
				    lastaddr);
				if (dr == NULL) {
					error = EINVAL;
					break;
				}

				/*
				 * In a valid DMA range.  Translate the
				 * physical memory address to an address
				 * in the DMA window.
				 */
				lastaddr = (lastaddr - dr->dr_sysbase) +
				    dr->dr_busbase;
			}
			map->dm_segs[seg].ds_addr = lastaddr;
			map->dm_segs[seg].ds_len = m->m_len;
			lastaddr += m->m_len;
			break;

		case 0:
			lastaddr = m->m_paddr + M_BUFOFFSET(m) +
			    (m->m_data - M_BUFADDR(m));
			goto have_addr;

		default:
			error = _bus_dmamap_load_buffer(t, map, m->m_data,
			    m->m_len, NULL, flags, &lastaddr, &seg);
		}
	}
	if (error == 0) {
		map->dm_mapsize = m0->m_pkthdr.len;
		map->dm_nsegs = seg + 1;
		map->_dm_origbuf = m0;
		map->_dm_buftype = ARM32_BUFTYPE_MBUF;
		map->_dm_proc = NULL;	/* always kernel */
	}
#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)
{
	paddr_t lastaddr;
	int seg, i, error;
	bus_size_t minlen, resid;
	struct proc *p = NULL;
	struct iovec *iov;
	caddr_t addr;

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

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

	if (uio->uio_segflg == UIO_USERSPACE) {
		p = uio->uio_procp;
#ifdef DIAGNOSTIC
		if (p == NULL)
			panic("_bus_dmamap_load_uio: USERSPACE but no proc");
#endif
	}

	/* _bus_dmamap_load_buffer() clears this if we're not... */
	map->_dm_flags |= ARM32_DMAMAP_COHERENT;

	seg = -1;
	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 = (caddr_t)iov[i].iov_base;

		error = _bus_dmamap_load_buffer(t, map, addr, minlen,
		    p, flags, &lastaddr, &seg);

		resid -= minlen;
	}
	if (error == 0) {
		map->dm_mapsize = uio->uio_resid;
		map->dm_nsegs = seg + 1;
		map->_dm_origbuf = uio;
		map->_dm_buftype = ARM32_BUFTYPE_UIO;
		map->_dm_proc = p;
	}
	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_mapsize = 0;
	map->dm_nsegs = 0;
	map->_dm_origbuf = NULL;
	map->_dm_buftype = ARM32_BUFTYPE_INVALID;
	map->_dm_proc = NULL;
}

static __inline void
_bus_dmamap_sync_linear(bus_dma_tag_t t, bus_dmamap_t map, bus_addr_t offset,
    bus_size_t len, int ops)
{
	vaddr_t addr = (vaddr_t) map->_dm_origbuf;

	addr += offset;

	switch (ops) {
	case BUS_DMASYNC_PREREAD|BUS_DMASYNC_PREWRITE:
		cpu_dcache_wbinv_range(addr, len);
		break;

	case BUS_DMASYNC_PREREAD:
		if (((addr | len) & arm_dcache_align_mask) == 0)
			cpu_dcache_inv_range(addr, len);
		else
			cpu_dcache_wbinv_range(addr, len);
		break;

	case BUS_DMASYNC_PREWRITE:
		cpu_dcache_wb_range(addr, len);
		break;
	}
}

static __inline void
_bus_dmamap_sync_mbuf(bus_dma_tag_t t, bus_dmamap_t map, bus_addr_t offset,
    bus_size_t len, int ops)
{
	struct mbuf *m, *m0 = map->_dm_origbuf;
	bus_size_t minlen, moff;
	vaddr_t maddr;

	for (moff = offset, m = m0; m != NULL && len != 0;
	     m = m->m_next) {
		/* Find the beginning mbuf. */
		if (moff >= m->m_len) {
			moff -= m->m_len;
			continue;
		}

		/*
		 * Now at the first mbuf to sync; nail each one until
		 * we have exhausted the length.
		 */
		minlen = m->m_len - moff;
		if (len < minlen)
			minlen = len;

		maddr = mtod(m, vaddr_t);
		maddr += moff;

		/*
		 * We can save a lot of work here if we know the mapping
		 * is read-only at the MMU:
		 *
		 * If a mapping is read-only, no dirty cache blocks will
		 * exist for it.  If a writable mapping was made read-only,
		 * we know any dirty cache lines for the range will have
		 * been cleaned for us already.  Therefore, if the upper
		 * layer can tell us we have a read-only mapping, we can
		 * skip all cache cleaning.
		 *
		 * NOTE: This only works if we know the pmap cleans pages
		 * before making a read-write -> read-only transition.  If
		 * this ever becomes non-true (e.g. Physically Indexed
		 * cache), this will have to be revisited.
		 */
		switch (ops) {
		case BUS_DMASYNC_PREREAD|BUS_DMASYNC_PREWRITE:
			if (! M_ROMAP(m)) {
				cpu_dcache_wbinv_range(maddr, minlen);
				break;
			}
			/* else FALLTHROUGH */

		case BUS_DMASYNC_PREREAD:
			if (((maddr | minlen) & arm_dcache_align_mask) == 0)
				cpu_dcache_inv_range(maddr, minlen);
			else
				cpu_dcache_wbinv_range(maddr, minlen);
			break;

		case BUS_DMASYNC_PREWRITE:
			if (! M_ROMAP(m))
				cpu_dcache_wb_range(maddr, minlen);
			break;
		}
		moff = 0;
		len -= minlen;
	}
}

static __inline void
_bus_dmamap_sync_uio(bus_dma_tag_t t, bus_dmamap_t map, bus_addr_t offset,
    bus_size_t len, int ops)
{
	struct uio *uio = map->_dm_origbuf;
	struct iovec *iov;
	bus_size_t minlen, ioff;
	vaddr_t addr;

	for (iov = uio->uio_iov, ioff = offset; len != 0; iov++) {
		/* Find the beginning iovec. */
		if (ioff >= iov->iov_len) {
			ioff -= iov->iov_len;
			continue;
		}

		/*
		 * Now at the first iovec to sync; nail each one until
		 * we have exhausted the length.
		 */
		minlen = iov->iov_len - ioff;
		if (len < minlen)
			minlen = len;

		addr = (vaddr_t) iov->iov_base;
		addr += ioff;

		switch (ops) {
		case BUS_DMASYNC_PREREAD|BUS_DMASYNC_PREWRITE:
			cpu_dcache_wbinv_range(addr, minlen);
			break;

		case BUS_DMASYNC_PREREAD:
			if (((addr | minlen) & arm_dcache_align_mask) == 0)
				cpu_dcache_inv_range(addr, minlen);
			else
				cpu_dcache_wbinv_range(addr, minlen);
			break;

		case BUS_DMASYNC_PREWRITE:
			cpu_dcache_wb_range(addr, minlen);
			break;
		}
		ioff = 0;
		len -= minlen;
	}
}

/*
 * Common function for DMA map synchronization.  May be called
 * by bus-specific DMA map synchronization functions.
 *
 * This version works for the Virtually Indexed Virtually Tagged
 * cache found on 32-bit ARM processors.
 *
 * XXX Should have separate versions for write-through vs.
 * XXX write-back caches.  We currently assume write-back
 * XXX here, which is not as efficient as it could be for
 * XXX the write-through case.
 */
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 */

	/*
	 * Mixing of 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: mix PRE and POST");

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

	/*
	 * For a virtually-indexed write-back cache, we need
	 * to do the following things:
	 *
	 *	PREREAD -- Invalidate the D-cache.  We do this
	 *	here in case a write-back is required by the back-end.
	 *
	 *	PREWRITE -- Write-back the D-cache.  Note that if
	 *	we are doing a PREREAD|PREWRITE, we can collapse
	 *	the whole thing into a single Wb-Inv.
	 *
	 *	POSTREAD -- Nothing.
	 *
	 *	POSTWRITE -- Nothing.
	 */

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

	/* Skip cache frobbing if mapping was COHERENT. */
	if (map->_dm_flags & ARM32_DMAMAP_COHERENT) {
		/* Drain the write buffer. */
		cpu_drain_writebuf();
		return;
	}

	/*
	 * If the mapping belongs to a non-kernel vmspace, and the
	 * vmspace has not been active since the last time a full
	 * cache flush was performed, we don't need to do anything.
	 */
	if (__predict_false(map->_dm_proc != NULL &&
	    map->_dm_proc->p_vmspace->vm_map.pmap->pm_cstate.cs_cache_d == 0))
		return;

	switch (map->_dm_buftype) {
	case ARM32_BUFTYPE_LINEAR:
		_bus_dmamap_sync_linear(t, map, offset, len, ops);
		break;

	case ARM32_BUFTYPE_MBUF:
		_bus_dmamap_sync_mbuf(t, map, offset, len, ops);
		break;

	case ARM32_BUFTYPE_UIO:
		_bus_dmamap_sync_uio(t, map, offset, len, ops);
		break;

	case ARM32_BUFTYPE_RAW:
		panic("_bus_dmamap_sync: ARM32_BUFTYPE_RAW");
		break;

	case ARM32_BUFTYPE_INVALID:
		panic("_bus_dmamap_sync: ARM32_BUFTYPE_INVALID");
		break;

	default:
		printf("unknown buffer type %d\n", map->_dm_buftype);
		panic("_bus_dmamap_sync");
	}

	/* Drain the write buffer. */
	cpu_drain_writebuf();
}

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

extern paddr_t physical_start;
extern paddr_t physical_end;

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)
{
	struct arm32_dma_range *dr;
	int error, i;

#ifdef DEBUG_DMA
	printf("dmamem_alloc t=%p size=%lx align=%lx boundary=%lx "
	    "segs=%p nsegs=%x rsegs=%p flags=%x\n", t, size, alignment,
	    boundary, segs, nsegs, rsegs, flags);
#endif

	if ((dr = t->_ranges) != NULL) {
		error = ENOMEM;
		for (i = 0; i < t->_nranges; i++, dr++) {
			if (dr->dr_len == 0)
				continue;
			error = _bus_dmamem_alloc_range(t, size, alignment,
			    boundary, segs, nsegs, rsegs, flags,
			    trunc_page(dr->dr_sysbase),
			    trunc_page(dr->dr_sysbase + dr->dr_len));
			if (error == 0)
				break;
		}
	} else {
		error = _bus_dmamem_alloc_range(t, size, alignment, boundary,
		    segs, nsegs, rsegs, flags, trunc_page(physical_start),
		    trunc_page(physical_end));
	}

#ifdef DEBUG_DMA
	printf("dmamem_alloc: =%d\n", error);
#endif

	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);
		}
	}
	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, caddr_t *kvap, int flags)
{
	vaddr_t va;
	bus_addr_t addr;
	int curseg;
	pt_entry_t *ptep/*, pte*/;

#ifdef DEBUG_DMA
	printf("dmamem_map: t=%p segs=%p nsegs=%x size=%lx flags=%x\n", t,
	    segs, nsegs, (unsigned long)size, flags);
#endif	/* DEBUG_DMA */

	size = round_page(size);
	va = uvm_km_valloc(kernel_map, size);

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

	*kvap = (caddr_t)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) {
#ifdef DEBUG_DMA
			printf("wiring p%lx to v%lx", addr, va);
#endif	/* DEBUG_DMA */
			if (size == 0)
				panic("_bus_dmamem_map: size botch");
			pmap_enter(pmap_kernel(), va, addr,
			    VM_PROT_READ | VM_PROT_WRITE,
			    VM_PROT_READ | VM_PROT_WRITE | PMAP_WIRED);
			/*
			 * If the memory must remain coherent with the
			 * cache then we must make the memory uncacheable
			 * in order to maintain virtual cache coherency.
			 * We must also guarantee the cache does not already
			 * contain the virtal addresses we are making
			 * uncacheable.
			 */
			if (flags & BUS_DMA_COHERENT) {
				cpu_dcache_wbinv_range(va, PAGE_SIZE);
				cpu_drain_writebuf();
				ptep = vtopte(va);
				*ptep &= ~L2_S_CACHE_MASK;
				PTE_SYNC(ptep);
				tlb_flush();
			}
#ifdef DEBUG_DMA
			ptep = vtopte(va);
			printf(" pte=v%p *pte=%x\n", ptep, *ptep);
#endif	/* DEBUG_DMA */
		}
	}
	pmap_update(pmap_kernel());
#ifdef DEBUG_DMA
	printf("dmamem_map: =%p\n", *kvap);
#endif	/* DEBUG_DMA */
	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, caddr_t kva, size_t size)
{

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

	size = round_page(size);
	uvm_km_free(kernel_map, (vaddr_t)kva, size);
}

/*
 * Common functin 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 (arm_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 entrace, 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 proc *p, int flags, paddr_t *lastaddrp,
    int *segp)
{
	struct arm32_dma_range *dr;
	bus_size_t sgsize;
	bus_addr_t curaddr, lastaddr, baddr, bmask;
	vaddr_t vaddr = (vaddr_t)buf;
	pd_entry_t *pde;
	pt_entry_t pte;
	int seg;
	pmap_t pmap;
	pt_entry_t *ptep;

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

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

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

	for (seg = *segp; buflen > 0; ) {
		/*
		 * Get the physical address for this segment.
		 *
		 * XXX Don't support checking for coherent mappings
		 * XXX in user address space.
		 */
		if (__predict_true(pmap == pmap_kernel())) {
			(void) pmap_get_pde_pte(pmap, vaddr, &pde, &ptep);
			if (__predict_false(pmap_pde_section(pde))) {
				curaddr = (*pde & L1_S_FRAME) |
				    (vaddr & L1_S_OFFSET);
				if (*pde & L1_S_CACHE_MASK) {
					map->_dm_flags &=
					    ~ARM32_DMAMAP_COHERENT;
				}
			} else {
				pte = *ptep;
				KDASSERT((pte & L2_TYPE_MASK) != L2_TYPE_INV);
				if (__predict_false((pte & L2_TYPE_MASK)
						    == L2_TYPE_L)) {
					curaddr = (pte & L2_L_FRAME) |
					    (vaddr & L2_L_OFFSET);
					if (pte & L2_L_CACHE_MASK) {
						map->_dm_flags &=
						    ~ARM32_DMAMAP_COHERENT;
					}
				} else {
					curaddr = (pte & L2_S_FRAME) |
					    (vaddr & L2_S_OFFSET);
					if (pte & L2_S_CACHE_MASK) {
						map->_dm_flags &=
						    ~ARM32_DMAMAP_COHERENT;
					}
				}
			}
		} else {
			(void) pmap_extract(pmap, vaddr, &curaddr);
			map->_dm_flags &= ~ARM32_DMAMAP_COHERENT;
		}

		/*
		 * Make sure we're in an allowed DMA range.
		 */
		if (t->_ranges != NULL) {
			/* XXX cache last result? */
			dr = _bus_dma_inrange(t->_ranges, t->_nranges,
			    curaddr);
			if (dr == NULL)
				return (EINVAL);

			/*
			 * In a valid DMA range.  Translate the physical
			 * memory address to an address in the DMA window.
			 */
			curaddr = (curaddr - dr->dr_sysbase) + dr->dr_busbase;
		}

		/*
		 * 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 (seg >= 0 && 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))) {
		     	/* coalesce */
			map->dm_segs[seg].ds_len += sgsize;
		} else if (++seg >= map->_dm_segcnt) {
			/* EFBIG */
			break;
		} else {
			/* new segment */
			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);
}

/*
 * 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, paddr_t low, paddr_t high)
{
	paddr_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.tqe_next;

	for (; m != NULL; m = m->pageq.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);
}

/*
 * Check if a memory region intersects with a DMA range, and return the
 * page-rounded intersection if it does.
 */
int
arm32_dma_range_intersect(struct arm32_dma_range *ranges, int nranges,
    paddr_t pa, psize_t size, paddr_t *pap, psize_t *sizep)
{
	struct arm32_dma_range *dr;
	int i;

	if (ranges == NULL)
		return (0);

	for (i = 0, dr = ranges; i < nranges; i++, dr++) {
		if (dr->dr_sysbase <= pa &&
		    pa < (dr->dr_sysbase + dr->dr_len)) {
			/*
			 * Beginning of region intersects with this range.
			 */
			*pap = trunc_page(pa);
			*sizep = round_page(min(pa + size,
			    dr->dr_sysbase + dr->dr_len) - pa);
			return (1);
		}
		if (pa < dr->dr_sysbase && dr->dr_sysbase < (pa + size)) {
			/*
			 * End of region intersects with this range.
			 */
			*pap = trunc_page(dr->dr_sysbase);
			*sizep = round_page(min((pa + size) - dr->dr_sysbase,
			    dr->dr_len));
			return (1);
		}
	}

	/* No intersection found. */
	return (0);
}