/*      $NetBSD: intio.c,v 1.52 2022/05/26 14:33:29 tsutsui Exp $       */

/*-
* Copyright (c) 1998 The NetBSD Foundation, Inc.
* 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 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.
*/

/*
* NetBSD/x68k internal I/O virtual bus.
*/

#include <sys/cdefs.h>
__KERNEL_RCSID(0, "$NetBSD: intio.c,v 1.52 2022/05/26 14:33:29 tsutsui Exp $");

#include <sys/param.h>
#include <sys/systm.h>
#include <sys/device.h>
#include <sys/malloc.h>
#include <sys/mbuf.h>
#include <sys/extent.h>
#include <uvm/uvm_extern.h>

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

#include <arch/x68k/dev/intiovar.h>

#include "ioconf.h"

/*
* bus_space(9) interface
*/
static int intio_bus_space_map(bus_space_tag_t, bus_addr_t, bus_size_t, int, bus_space_handle_t *);
static void intio_bus_space_unmap(bus_space_tag_t, bus_space_handle_t, bus_size_t);
static int intio_bus_space_subregion(bus_space_tag_t, bus_space_handle_t, bus_size_t, bus_size_t, bus_space_handle_t *);

static struct x68k_bus_space intio_bus = {
#if 0
       X68K_INTIO_BUS,
#endif
       intio_bus_space_map, intio_bus_space_unmap, intio_bus_space_subregion,
       x68k_bus_space_alloc, x68k_bus_space_free,
#if 0
       x68k_bus_space_barrier,
#endif

       0
};

/*
* bus_dma(9) interface
*/
#define INTIO_DMA_BOUNCE_THRESHOLD      (16 * 1024 * 1024)
int     _intio_bus_dmamap_create(bus_dma_tag_t, bus_size_t, int,
           bus_size_t, bus_size_t, int, bus_dmamap_t *);
void    _intio_bus_dmamap_destroy(bus_dma_tag_t, bus_dmamap_t);
int     _intio_bus_dmamap_load(bus_dma_tag_t, bus_dmamap_t, void *,
           bus_size_t, struct proc *, int);
int     _intio_bus_dmamap_load_mbuf(bus_dma_tag_t, bus_dmamap_t,
           struct mbuf *, int);
int     _intio_bus_dmamap_load_uio(bus_dma_tag_t, bus_dmamap_t,
           struct uio *, int);
int     _intio_bus_dmamap_load_raw(bus_dma_tag_t, bus_dmamap_t,
           bus_dma_segment_t *, int, bus_size_t, int);
void    _intio_bus_dmamap_unload(bus_dma_tag_t, bus_dmamap_t);
void    _intio_bus_dmamap_sync(bus_dma_tag_t, bus_dmamap_t,
           bus_addr_t, bus_size_t, int);

int     _intio_bus_dmamem_alloc(bus_dma_tag_t, bus_size_t, bus_size_t,
           bus_size_t, bus_dma_segment_t *, int, int *, int);

int     _intio_dma_alloc_bouncebuf(bus_dma_tag_t, bus_dmamap_t,
           bus_size_t, int);
void    _intio_dma_free_bouncebuf(bus_dma_tag_t, bus_dmamap_t);

struct x68k_bus_dma intio_bus_dma = {
       INTIO_DMA_BOUNCE_THRESHOLD,
       _intio_bus_dmamap_create,
       _intio_bus_dmamap_destroy,
       _intio_bus_dmamap_load,
       _intio_bus_dmamap_load_mbuf,
       _intio_bus_dmamap_load_uio,
       _intio_bus_dmamap_load_raw,
       _intio_bus_dmamap_unload,
       _intio_bus_dmamap_sync,
       _intio_bus_dmamem_alloc,
       x68k_bus_dmamem_free,
       x68k_bus_dmamem_map,
       x68k_bus_dmamem_unmap,
       x68k_bus_dmamem_mmap,
};

/*
* autoconf stuff
*/
static int intio_match(device_t, cfdata_t, void *);
static void intio_attach(device_t, device_t, void *);
static int intio_search(device_t, cfdata_t, const int *, void *);
static int intio_print(void *, const char *);
static void intio_alloc_system_ports(struct intio_softc*);

CFATTACH_DECL_NEW(intio, sizeof(struct intio_softc),
   intio_match, intio_attach, NULL, NULL);

static int intio_attached;

static struct intio_interrupt_vector {
       intio_intr_handler_t    iiv_handler;
       void                    *iiv_arg;
       struct evcnt            *iiv_evcnt;
} iiv[256] = {{0,},};

#ifdef DEBUG
int intio_debug = 0;
#endif

static int
intio_match(device_t parent, cfdata_t cf, void *aux)
{

       if (strcmp(aux, intio_cd.cd_name) != 0)
               return (0);
       if (intio_attached)
               return (0);

       return (1);
}

static void
intio_attach(device_t parent, device_t self, void *aux)
{
       struct intio_softc *sc = device_private(self);
       struct intio_attach_args ia;

       intio_attached = 1;

       aprint_normal(" mapped at %8p\n", intiobase);

       sc->sc_map = extent_create("intiomap",
                                 INTIOBASE,
                                 INTIOBASE + 0x400000,
                                 NULL, 0, EX_WAITOK);
       intio_alloc_system_ports(sc);

       sc->sc_bst = &intio_bus;
       sc->sc_bst->x68k_bus_device = self;
       sc->sc_dmat = &intio_bus_dma;
       sc->sc_dmac = 0;

       memset(iiv, 0, sizeof(struct intio_interrupt_vector) * 256);

       ia.ia_bst = sc->sc_bst;
       ia.ia_dmat = sc->sc_dmat;

       config_search(self, &ia,
           CFARGS(.search = intio_search));
}

static int
intio_search(device_t parent, cfdata_t cf, const int *ldesc, void *aux)
{
       struct intio_softc *sc = device_private(parent);
       struct intio_attach_args *ia = aux;

       ia->ia_bst = sc->sc_bst;
       ia->ia_dmat = sc->sc_dmat;
       ia->ia_name = cf->cf_name;
       ia->ia_addr = cf->cf_addr;
       ia->ia_intr = cf->cf_intr;
       ia->ia_dma = cf->cf_dma;
       ia->ia_dmaintr = cf->cf_dmaintr;

       if (config_probe(parent, cf, ia))
               config_attach(parent, cf, ia, intio_print, CFARGS_NONE);

       return (0);
}

static int
intio_print(void *aux, const char *name)
{
       struct intio_attach_args *ia = aux;

/*      if (ia->ia_addr > 0)    */
               aprint_normal(" addr 0x%06x", ia->ia_addr);
       if (ia->ia_intr > 0)
               aprint_normal(" intr 0x%02x", ia->ia_intr);
       if (ia->ia_dma >= 0) {
               aprint_normal(" using DMA ch%d", ia->ia_dma);
               if (ia->ia_dmaintr > 0)
                       aprint_normal(" intr 0x%02x and 0x%02x",
                               ia->ia_dmaintr, ia->ia_dmaintr+1);
       }

       return (QUIET);
}

/*
* intio memory map manager
*/

int
intio_map_allocate_region(device_t parent, struct intio_attach_args *ia,
   enum intio_map_flag flag)
{
       struct intio_softc *sc = device_private(parent);
       struct extent *map = sc->sc_map;
       int r;

       r = extent_alloc_region(map, ia->ia_addr, ia->ia_size, 0);
#ifdef DEBUG
       if (intio_debug)
               extent_print(map);
#endif
       if (r == 0) {
               if (flag != INTIO_MAP_ALLOCATE)
                       extent_free(map, ia->ia_addr, ia->ia_size, 0);
               return 0;
       }

       return -1;
}

int
intio_map_free_region(device_t parent, struct intio_attach_args *ia)
{
       struct intio_softc *sc = device_private(parent);
       struct extent *map = sc->sc_map;

       extent_free(map, ia->ia_addr, ia->ia_size, 0);
#ifdef DEBUG
       if (intio_debug)
               extent_print(map);
#endif
       return 0;
}

void
intio_alloc_system_ports(struct intio_softc *sc)
{
       extent_alloc_region(sc->sc_map, INTIO_SYSPORT, 16, 0);
       extent_alloc_region(sc->sc_map, INTIO_SICILIAN, 0x2000, 0);
}


/*
* intio bus space stuff.
*/
static int
intio_bus_space_map(bus_space_tag_t t, bus_addr_t bpa, bus_size_t size,
   int flags, bus_space_handle_t *bshp)
{
       /*
        * Intio bus is mapped permanently.
        */
       *bshp = (bus_space_handle_t)IIOV(bpa);

       /*
        * Some devices are mapped on odd or even addresses only.
        */
       if ((flags & BUS_SPACE_MAP_SHIFTED_MASK) == BUS_SPACE_MAP_SHIFTED_ODD)
               *bshp += 0x80000001;
       if ((flags & BUS_SPACE_MAP_SHIFTED_MASK) == BUS_SPACE_MAP_SHIFTED_EVEN)
               *bshp += 0x80000000;

       return (0);
}

static void
intio_bus_space_unmap(bus_space_tag_t t, bus_space_handle_t bsh,
   bus_size_t size)
{
       return;
}

static int
intio_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);
}


/*
* interrupt handler
*/
int
intio_intr_establish(int vector, const char *name, intio_intr_handler_t handler,
   void *arg)
{

       return intio_intr_establish_ext(vector, name, "intr", handler, arg);
}

int
intio_intr_establish_ext(int vector, const char *name1, const char *name2,
       intio_intr_handler_t handler, void *arg)
{
       struct evcnt *evcnt;

       if (vector < 16)
               panic("Invalid interrupt vector");
       if (iiv[vector].iiv_handler)
               return EBUSY;

       evcnt = malloc(sizeof(*evcnt), M_DEVBUF, M_WAITOK);
       evcnt_attach_dynamic(evcnt, EVCNT_TYPE_INTR, NULL, name1, name2);

       iiv[vector].iiv_handler = handler;
       iiv[vector].iiv_arg = arg;
       iiv[vector].iiv_evcnt = evcnt;

       return 0;
}

int
intio_intr_disestablish(int vector, void *arg)
{
       if (iiv[vector].iiv_handler == 0 || iiv[vector].iiv_arg != arg)
               return EINVAL;
       iiv[vector].iiv_handler = 0;
       iiv[vector].iiv_arg = 0;
       evcnt_detach(iiv[vector].iiv_evcnt);
       free(iiv[vector].iiv_evcnt, M_DEVBUF);

       return 0;
}

int
intio_intr(struct frame *frame)
{
       int vector = frame->f_vector / 4;

       if (iiv[vector].iiv_handler == 0) {
               printf("Stray interrupt: %d type %x, pc %x\n",
                       vector, frame->f_format, frame->f_pc);
               return 0;
       }

       iiv[vector].iiv_evcnt->ev_count++;

       return (*(iiv[vector].iiv_handler))(iiv[vector].iiv_arg);
}

/*
* Intio I/O controller interrupt
*/
static u_int8_t intio_ivec = 0;

void
intio_set_ivec(int vec)
{
       vec &= 0xfc;

       if (intio_ivec && intio_ivec != (vec & 0xfc))
               panic("Wrong interrupt vector for Sicilian.");

       intio_ivec = vec;
       intio_set_sicilian_ivec(vec);
}


/*
* intio bus DMA stuff.  stolen from arch/i386/isa/isa_machdep.c
*/

/*
* Create an INTIO DMA map.
*/
int
_intio_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 intio_dma_cookie *cookie;
       bus_dmamap_t map;
       int error, cookieflags;
       size_t cookiesize;
       extern paddr_t avail_end;

       /* Call common function to create the basic map. */
       error = x68k_bus_dmamap_create(t, size, nsegments, maxsegsz, boundary,
           flags, dmamp);
       if (error)
               return (error);

       map = *dmamp;
       map->x68k_dm_cookie = NULL;

       cookiesize = sizeof(struct intio_dma_cookie);

       /*
        * INTIO only has 24-bits of address space.  This means
        * we can't DMA to pages over 16M.  In order to DMA to
        * arbitrary buffers, we use "bounce buffers" - pages
        * in memory below the 16M boundary.  On DMA reads,
        * DMA happens to the bounce buffers, and is copied into
        * the caller's buffer.  On writes, data is copied into
        * the bounce buffer, and the DMA happens from those
        * pages.  To software using the DMA mapping interface,
        * this looks simply like a data cache.
        *
        * If we have more than 16M of RAM in the system, we may
        * need bounce buffers.  We check and remember that here.
        *
        * ...or, there is an opposite case.  The most segments
        * a transfer will require is (maxxfer / PAGE_SIZE) + 1.  If
        * the caller can't handle that many segments (e.g. the
        * DMAC), we may have to bounce it as well.
        */
       if (avail_end <= t->_bounce_thresh)
               /* Bouncing not necessary due to memory size. */
               map->x68k_dm_bounce_thresh = 0;
       cookieflags = 0;
       if (map->x68k_dm_bounce_thresh != 0 ||
           ((map->x68k_dm_size / PAGE_SIZE) + 1) > map->x68k_dm_segcnt) {
               cookieflags |= ID_MIGHT_NEED_BOUNCE;
               cookiesize += (sizeof(bus_dma_segment_t) * map->x68k_dm_segcnt);
       }

       /*
        * Allocate our cookie.
        */
       cookie = malloc(cookiesize, M_DMAMAP,
           ((flags & BUS_DMA_NOWAIT) ? M_NOWAIT : M_WAITOK) | M_ZERO);
       if (cookie == NULL) {
               error = ENOMEM;
               goto out;
       }
       cookie->id_flags = cookieflags;
       map->x68k_dm_cookie = cookie;

       if (cookieflags & ID_MIGHT_NEED_BOUNCE) {
               /*
                * Allocate the bounce pages now if the caller
                * wishes us to do so.
                */
               if ((flags & BUS_DMA_ALLOCNOW) == 0)
                       goto out;

               error = _intio_dma_alloc_bouncebuf(t, map, size, flags);
       }

out:
       if (error) {
               if (map->x68k_dm_cookie != NULL)
                       free(map->x68k_dm_cookie, M_DMAMAP);
               x68k_bus_dmamap_destroy(t, map);
       }
       return (error);
}

/*
* Destroy an INTIO DMA map.
*/
void
_intio_bus_dmamap_destroy(bus_dma_tag_t t, bus_dmamap_t map)
{
       struct intio_dma_cookie *cookie = map->x68k_dm_cookie;

       /*
        * Free any bounce pages this map might hold.
        */
       if (cookie->id_flags & ID_HAS_BOUNCE)
               _intio_dma_free_bouncebuf(t, map);

       free(cookie, M_DMAMAP);
       x68k_bus_dmamap_destroy(t, map);
}

/*
* Load an INTIO DMA map with a linear buffer.
*/
int
_intio_bus_dmamap_load(bus_dma_tag_t t, bus_dmamap_t map, void *buf,
   bus_size_t buflen, struct proc *p, int flags)
{
       struct intio_dma_cookie *cookie = map->x68k_dm_cookie;
       int error;

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

       /*
        * Try to load the map the normal way.  If this errors out,
        * and we can bounce, we will.
        */
       error = x68k_bus_dmamap_load(t, map, buf, buflen, p, flags);
       if (error == 0 || (cookie->id_flags & ID_MIGHT_NEED_BOUNCE) == 0)
               return (error);

       /*
        * Allocate bounce pages, if necessary.
        */
       if ((cookie->id_flags & ID_HAS_BOUNCE) == 0) {
               error = _intio_dma_alloc_bouncebuf(t, map, buflen, flags);
               if (error)
                       return (error);
       }

       /*
        * Cache a pointer to the caller's buffer and load the DMA map
        * with the bounce buffer.
        */
       cookie->id_origbuf = buf;
       cookie->id_origbuflen = buflen;
       cookie->id_buftype = ID_BUFTYPE_LINEAR;
       error = x68k_bus_dmamap_load(t, map, cookie->id_bouncebuf, buflen,
           p, flags);
       if (error) {
               /*
                * Free the bounce pages, unless our resources
                * are reserved for our exclusive use.
                */
               if ((map->x68k_dm_flags & BUS_DMA_ALLOCNOW) == 0)
                       _intio_dma_free_bouncebuf(t, map);
               return (error);
       }

       /* ...so _intio_bus_dmamap_sync() knows we're bouncing */
       cookie->id_flags |= ID_IS_BOUNCING;
       return (0);
}

/*
* Like _intio_bus_dmamap_load(), but for mbufs.
*/
int
_intio_bus_dmamap_load_mbuf(bus_dma_tag_t t, bus_dmamap_t map, struct mbuf *m0,
   int flags)
{
       struct intio_dma_cookie *cookie = map->x68k_dm_cookie;
       int error;

       /*
        * Make sure 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("_intio_bus_dmamap_load_mbuf: no packet header");
#endif

       if (m0->m_pkthdr.len > map->x68k_dm_size)
               return (EINVAL);

       /*
        * Try to load the map the normal way.  If this errors out,
        * and we can bounce, we will.
        */
       error = x68k_bus_dmamap_load_mbuf(t, map, m0, flags);
       if (error == 0 || (cookie->id_flags & ID_MIGHT_NEED_BOUNCE) == 0)
               return (error);

       /*
        * Allocate bounce pages, if necessary.
        */
       if ((cookie->id_flags & ID_HAS_BOUNCE) == 0) {
               error = _intio_dma_alloc_bouncebuf(t, map, m0->m_pkthdr.len,
                   flags);
               if (error)
                       return (error);
       }

       /*
        * Cache a pointer to the caller's buffer and load the DMA map
        * with the bounce buffer.
        */
       cookie->id_origbuf = m0;
       cookie->id_origbuflen = m0->m_pkthdr.len;       /* not really used */
       cookie->id_buftype = ID_BUFTYPE_MBUF;
       error = x68k_bus_dmamap_load(t, map, cookie->id_bouncebuf,
           m0->m_pkthdr.len, NULL, flags);
       if (error) {
               /*
                * Free the bounce pages, unless our resources
                * are reserved for our exclusive use.
                */
               if ((map->x68k_dm_flags & BUS_DMA_ALLOCNOW) == 0)
                       _intio_dma_free_bouncebuf(t, map);
               return (error);
       }

       /* ...so _intio_bus_dmamap_sync() knows we're bouncing */
       cookie->id_flags |= ID_IS_BOUNCING;
       return (0);
}

/*
* Like _intio_bus_dmamap_load(), but for uios.
*/
int
_intio_bus_dmamap_load_uio(bus_dma_tag_t t, bus_dmamap_t map, struct uio *uio,
   int flags)
{
       panic("_intio_bus_dmamap_load_uio: not implemented");
}

/*
* Like _intio_bus_dmamap_load(), but for raw memory allocated with
* bus_dmamem_alloc().
*/
int
_intio_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("_intio_bus_dmamap_load_raw: not implemented");
}

/*
* Unload an INTIO DMA map.
*/
void
_intio_bus_dmamap_unload(bus_dma_tag_t t, bus_dmamap_t map)
{
       struct intio_dma_cookie *cookie = map->x68k_dm_cookie;

       /*
        * If we have bounce pages, free them, unless they're
        * reserved for our exclusive use.
        */
       if ((cookie->id_flags & ID_HAS_BOUNCE) &&
           (map->x68k_dm_flags & BUS_DMA_ALLOCNOW) == 0)
               _intio_dma_free_bouncebuf(t, map);

       cookie->id_flags &= ~ID_IS_BOUNCING;
       cookie->id_buftype = ID_BUFTYPE_INVALID;

       /*
        * Do the generic bits of the unload.
        */
       x68k_bus_dmamap_unload(t, map);
}

/*
* Synchronize an INTIO DMA map.
*/
void
_intio_bus_dmamap_sync(bus_dma_tag_t t, bus_dmamap_t map, bus_addr_t offset,
   bus_size_t len, int ops)
{
       struct intio_dma_cookie *cookie = map->x68k_dm_cookie;

       /*
        * 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("_intio_bus_dmamap_sync: mix PRE and POST");

#ifdef DIAGNOSTIC
       if ((ops & (BUS_DMASYNC_PREWRITE|BUS_DMASYNC_POSTREAD)) != 0) {
               if (offset >= map->dm_mapsize)
                       panic("_intio_bus_dmamap_sync: bad offset");
               if (len == 0 || (offset + len) > map->dm_mapsize)
                       panic("_intio_bus_dmamap_sync: bad length");
       }
#endif

       /*
        * If we're not bouncing, just return; nothing to do.
        */
       if ((cookie->id_flags & ID_IS_BOUNCING) == 0)
               return;

       switch (cookie->id_buftype) {
       case ID_BUFTYPE_LINEAR:
               /*
                * Nothing to do for pre-read.
                */

               if (ops & BUS_DMASYNC_PREWRITE) {
                       /*
                        * Copy the caller's buffer to the bounce buffer.
                        */
                       memcpy((char *)cookie->id_bouncebuf + offset,
                           (char *)cookie->id_origbuf + offset, len);
               }

               if (ops & BUS_DMASYNC_POSTREAD) {
                       /*
                        * Copy the bounce buffer to the caller's buffer.
                        */
                       memcpy((char *)cookie->id_origbuf + offset,
                           (char *)cookie->id_bouncebuf + offset, len);
               }

               /*
                * Nothing to do for post-write.
                */
               break;

       case ID_BUFTYPE_MBUF:
           {
               struct mbuf *m, *m0 = cookie->id_origbuf;
               bus_size_t minlen, moff;

               /*
                * Nothing to do for pre-read.
                */

               if (ops & BUS_DMASYNC_PREWRITE) {
                       /*
                        * Copy the caller's buffer to the bounce buffer.
                        */
                       m_copydata(m0, offset, len,
                           (char *)cookie->id_bouncebuf + offset);
               }

               if (ops & BUS_DMASYNC_POSTREAD) {
                       /*
                        * Copy the bounce buffer to the caller's buffer.
                        */
                       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 = len < m->m_len - moff ?
                                   len : m->m_len - moff;

                               memcpy(mtod(m, char *) + moff,
                                   (char *)cookie->id_bouncebuf + offset,
                                   minlen);

                               moff = 0;
                               len -= minlen;
                               offset += minlen;
                       }
               }

               /*
                * Nothing to do for post-write.
                */
               break;
           }

       case ID_BUFTYPE_UIO:
               panic("_intio_bus_dmamap_sync: ID_BUFTYPE_UIO");
               break;

       case ID_BUFTYPE_RAW:
               panic("_intio_bus_dmamap_sync: ID_BUFTYPE_RAW");
               break;

       case ID_BUFTYPE_INVALID:
               panic("_intio_bus_dmamap_sync: ID_BUFTYPE_INVALID");
               break;

       default:
               printf("unknown buffer type %d\n", cookie->id_buftype);
               panic("_intio_bus_dmamap_sync");
       }
}

/*
* Allocate memory safe for INTIO DMA.
*/
int
_intio_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)
{
       paddr_t high;
       extern paddr_t avail_end;

       if (avail_end > INTIO_DMA_BOUNCE_THRESHOLD)
               high = trunc_page(INTIO_DMA_BOUNCE_THRESHOLD);
       else
               high = trunc_page(avail_end);

       return (x68k_bus_dmamem_alloc_range(t, size, alignment, boundary,
           segs, nsegs, rsegs, flags, 0, high));
}

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

int
_intio_dma_alloc_bouncebuf(bus_dma_tag_t t, bus_dmamap_t map, bus_size_t size,
   int flags)
{
       struct intio_dma_cookie *cookie = map->x68k_dm_cookie;
       int error = 0;

       cookie->id_bouncebuflen = round_page(size);
       error = _intio_bus_dmamem_alloc(t, cookie->id_bouncebuflen,
           PAGE_SIZE, map->x68k_dm_boundary, cookie->id_bouncesegs,
           map->x68k_dm_segcnt, &cookie->id_nbouncesegs, flags);
       if (error)
               goto out;
       error = x68k_bus_dmamem_map(t, cookie->id_bouncesegs,
           cookie->id_nbouncesegs, cookie->id_bouncebuflen,
           (void **)&cookie->id_bouncebuf, flags);

out:
       if (error) {
               x68k_bus_dmamem_free(t, cookie->id_bouncesegs,
                   cookie->id_nbouncesegs);
               cookie->id_bouncebuflen = 0;
               cookie->id_nbouncesegs = 0;
       } else {
               cookie->id_flags |= ID_HAS_BOUNCE;
       }

       return (error);
}

void
_intio_dma_free_bouncebuf(bus_dma_tag_t t, bus_dmamap_t map)
{
       struct intio_dma_cookie *cookie = map->x68k_dm_cookie;

       x68k_bus_dmamem_unmap(t, cookie->id_bouncebuf,
           cookie->id_bouncebuflen);
       x68k_bus_dmamem_free(t, cookie->id_bouncesegs,
           cookie->id_nbouncesegs);
       cookie->id_bouncebuflen = 0;
       cookie->id_nbouncesegs = 0;
       cookie->id_flags &= ~ID_HAS_BOUNCE;
}