xref: /netbsd-src/sys/arch/powerpc/isa/isadma_machdep.c (revision 7fa608457b817eca6e0977b37f758ae064f3c99c)
1 /*	$NetBSD: isadma_machdep.c,v 1.4 2007/03/07 17:22:27 he Exp $	*/
2 
3 /*-
4  * Copyright (c) 1996, 1997, 1998 The NetBSD Foundation, Inc.
5  * All rights reserved.
6  *
7  * This code is derived from software contributed to The NetBSD Foundation
8  * by Jason R. Thorpe of the Numerical Aerospace Simulation Facility,
9  * NASA Ames Research Center.
10  *
11  * Redistribution and use in source and binary forms, with or without
12  * modification, are permitted provided that the following conditions
13  * are met:
14  * 1. Redistributions of source code must retain the above copyright
15  *    notice, this list of conditions and the following disclaimer.
16  * 2. Redistributions in binary form must reproduce the above copyright
17  *    notice, this list of conditions and the following disclaimer in the
18  *    documentation and/or other materials provided with the distribution.
19  * 3. All advertising materials mentioning features or use of this software
20  *    must display the following acknowledgement:
21  *	This product includes software developed by the NetBSD
22  *	Foundation, Inc. and its contributors.
23  * 4. Neither the name of The NetBSD Foundation nor the names of its
24  *    contributors may be used to endorse or promote products derived
25  *    from this software without specific prior written permission.
26  *
27  * THIS SOFTWARE IS PROVIDED BY THE NETBSD FOUNDATION, INC. AND CONTRIBUTORS
28  * ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED
29  * TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
30  * PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL THE FOUNDATION OR CONTRIBUTORS
31  * BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
32  * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
33  * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
34  * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
35  * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
36  * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
37  * POSSIBILITY OF SUCH DAMAGE.
38  */
39 
40 #include <sys/cdefs.h>
41 __KERNEL_RCSID(0, "$NetBSD: isadma_machdep.c,v 1.4 2007/03/07 17:22:27 he Exp $");
42 
43 #define ISA_DMA_STATS
44 
45 #include <sys/param.h>
46 #include <sys/systm.h>
47 #include <sys/syslog.h>
48 #include <sys/device.h>
49 #include <sys/malloc.h>
50 #include <sys/proc.h>
51 #include <sys/mbuf.h>
52 
53 #define _POWERPC_BUS_DMA_PRIVATE
54 #include <machine/bus.h>
55 
56 #include <machine/pio.h>
57 
58 #include <dev/isa/isareg.h>
59 #include <dev/isa/isavar.h>
60 
61 #include <uvm/uvm.h>
62 
63 /*
64  * Cookie used by ISA dma.  A pointer to one of these it stashed in
65  * the DMA map.
66  */
67 struct powerpc_isa_dma_cookie {
68 	int	id_flags;		/* flags; see below */
69 
70 	/*
71 	 * Information about the original buffer used during
72 	 * DMA map syncs.  Note that origbuflen is only used
73 	 * for ID_BUFTYPE_LINEAR.
74 	 */
75 	void	*id_origbuf;		/* pointer to orig buffer if
76 					   bouncing */
77 	bus_size_t id_origbuflen;	/* ...and size */
78 	int	id_buftype;		/* type of buffer */
79 
80 	void	*id_bouncebuf;		/* pointer to the bounce buffer */
81 	bus_size_t id_bouncebuflen;	/* ...and size */
82 	int	id_nbouncesegs;		/* number of valid bounce segs */
83 	bus_dma_segment_t id_bouncesegs[0]; /* array of bounce buffer
84 					       physical memory segments */
85 };
86 
87 /* id_flags */
88 #define	ID_MIGHT_NEED_BOUNCE	0x01	/* map could need bounce buffers */
89 #define	ID_HAS_BOUNCE		0x02	/* map currently has bounce buffers */
90 #define	ID_IS_BOUNCING		0x04	/* map is bouncing current xfer */
91 
92 /* id_buftype */
93 #define	ID_BUFTYPE_INVALID	0
94 #define	ID_BUFTYPE_LINEAR	1
95 #define	ID_BUFTYPE_MBUF		2
96 #define	ID_BUFTYPE_UIO		3
97 #define	ID_BUFTYPE_RAW		4
98 
99 static int	_isa_bus_dmamap_create(bus_dma_tag_t, bus_size_t, int,
100 		    bus_size_t, bus_size_t, int, bus_dmamap_t *);
101 static void	_isa_bus_dmamap_destroy(bus_dma_tag_t, bus_dmamap_t);
102 static int	_isa_bus_dmamap_load(bus_dma_tag_t, bus_dmamap_t, void *,
103 		    bus_size_t, struct proc *, int);
104 static int	_isa_bus_dmamap_load_mbuf(bus_dma_tag_t, bus_dmamap_t,
105 		    struct mbuf *, int);
106 static int	_isa_bus_dmamap_load_uio(bus_dma_tag_t, bus_dmamap_t,
107 		    struct uio *, int);
108 static int	_isa_bus_dmamap_load_raw(bus_dma_tag_t, bus_dmamap_t,
109 		    bus_dma_segment_t *, int, bus_size_t, int);
110 static void	_isa_bus_dmamap_unload(bus_dma_tag_t, bus_dmamap_t);
111 static void	_isa_bus_dmamap_sync(bus_dma_tag_t, bus_dmamap_t,
112 		    bus_addr_t, bus_size_t, int);
113 
114 static int	_isa_bus_dmamem_alloc(bus_dma_tag_t, bus_size_t, bus_size_t,
115 		    bus_size_t, bus_dma_segment_t *, int, int *, int);
116 
117 static int	_isa_dma_alloc_bouncebuf(bus_dma_tag_t, bus_dmamap_t,
118 		    bus_size_t, int);
119 static void	_isa_dma_free_bouncebuf(bus_dma_tag_t, bus_dmamap_t);
120 
121 /*
122  * Entry points for ISA DMA.  These are mostly wrappers around
123  * the generic functions that understand how to deal with bounce
124  * buffers, if necessary.
125  */
126 struct powerpc_bus_dma_tag isa_bus_dma_tag = {
127 	ISA_DMA_BOUNCE_THRESHOLD,
128 	_isa_bus_dmamap_create,
129 	_isa_bus_dmamap_destroy,
130 	_isa_bus_dmamap_load,
131 	_isa_bus_dmamap_load_mbuf,
132 	_isa_bus_dmamap_load_uio,
133 	_isa_bus_dmamap_load_raw,
134 	_isa_bus_dmamap_unload,
135 	_isa_bus_dmamap_sync,
136 	_isa_bus_dmamem_alloc,
137 	_bus_dmamem_free,
138 	_bus_dmamem_map,
139 	_bus_dmamem_unmap,
140 	_bus_dmamem_mmap,
141 };
142 
143 /**********************************************************************
144  * bus.h dma interface entry points
145  **********************************************************************/
146 
147 #ifdef ISA_DMA_STATS
148 #define	STAT_INCR(v)	(v)++
149 #define	STAT_DECR(v)	do { \
150 		if ((v) == 0) \
151 			printf("%s:%d -- Already 0!\n", __FILE__, __LINE__); \
152 		else \
153 			(v)--; \
154 		} while (0)
155 u_long	isa_dma_stats_loads;
156 u_long	isa_dma_stats_bounces;
157 u_long	isa_dma_stats_nbouncebufs;
158 #else
159 #define	STAT_INCR(v)
160 #define	STAT_DECR(v)
161 #endif
162 
163 /*
164  * Create an ISA DMA map.
165  */
166 int
167 _isa_bus_dmamap_create(bus_dma_tag_t t, bus_size_t size, int nsegments,
168 	bus_size_t maxsegsz, bus_size_t boundary, int flags,
169 	bus_dmamap_t *dmamp)
170 {
171 	struct powerpc_isa_dma_cookie *cookie;
172 	bus_dmamap_t map;
173 	int error, cookieflags, bank;
174 	void *cookiestore;
175 	size_t cookiesize;
176 	paddr_t avail_end = 0;
177 
178 	for (bank = 0; bank < vm_nphysseg; bank++) {
179 		if (avail_end < vm_physmem[bank].avail_end << PGSHIFT)
180 			avail_end = vm_physmem[bank].avail_end << PGSHIFT;
181 	}
182 
183 	/* Call common function to create the basic map. */
184 	error = _bus_dmamap_create(t, size, nsegments, maxsegsz, boundary,
185 	    flags, dmamp);
186 	if (error)
187 		return (error);
188 
189 	map = *dmamp;
190 	map->_dm_cookie = NULL;
191 
192 	cookiesize = sizeof(struct powerpc_isa_dma_cookie);
193 
194 	/*
195 	 * ISA only has 24-bits of address space.  This means
196 	 * we can't DMA to pages over 16M.  In order to DMA to
197 	 * arbitrary buffers, we use "bounce buffers" - pages
198 	 * in memory below the 16M boundary.  On DMA reads,
199 	 * DMA happens to the bounce buffers, and is copied into
200 	 * the caller's buffer.  On writes, data is copied into
201 	 * but bounce buffer, and the DMA happens from those
202 	 * pages.  To software using the DMA mapping interface,
203 	 * this looks simply like a data cache.
204 	 *
205 	 * If we have more than 16M of RAM in the system, we may
206 	 * need bounce buffers.  We check and remember that here.
207 	 *
208 	 * There are exceptions, however.  VLB devices can do
209 	 * 32-bit DMA, and indicate that here.
210 	 *
211 	 * ...or, there is an opposite case.  The most segments
212 	 * a transfer will require is (maxxfer / PAGE_SIZE) + 1.  If
213 	 * the caller can't handle that many segments (e.g. the
214 	 * ISA DMA controller), we may have to bounce it as well.
215 	 */
216 	if (avail_end <= t->_bounce_thresh ||
217 	    (flags & ISABUS_DMA_32BIT) != 0) {
218 		/* Bouncing not necessary due to memory size. */
219 		map->_dm_bounce_thresh = 0;
220 	}
221 	cookieflags = 0;
222 	if (map->_dm_bounce_thresh != 0 ||
223 	    ((map->_dm_size / PAGE_SIZE) + 1) > map->_dm_segcnt) {
224 		cookieflags |= ID_MIGHT_NEED_BOUNCE;
225 		cookiesize += (sizeof(bus_dma_segment_t) * map->_dm_segcnt);
226 	}
227 
228 	/*
229 	 * Allocate our cookie.
230 	 */
231 	if ((cookiestore = malloc(cookiesize, M_DMAMAP,
232 	    (flags & BUS_DMA_NOWAIT) ? M_NOWAIT : M_WAITOK)) == NULL) {
233 		error = ENOMEM;
234 		goto out;
235 	}
236 	memset(cookiestore, 0, cookiesize);
237 	cookie = (struct powerpc_isa_dma_cookie *)cookiestore;
238 	cookie->id_flags = cookieflags;
239 	map->_dm_cookie = cookie;
240 
241 	if (cookieflags & ID_MIGHT_NEED_BOUNCE) {
242 		/*
243 		 * Allocate the bounce pages now if the caller
244 		 * wishes us to do so.
245 		 */
246 		if ((flags & BUS_DMA_ALLOCNOW) == 0)
247 			goto out;
248 
249 		error = _isa_dma_alloc_bouncebuf(t, map, size, flags);
250 	}
251 
252  out:
253 	if (error) {
254 		if (map->_dm_cookie != NULL)
255 			free(map->_dm_cookie, M_DMAMAP);
256 		_bus_dmamap_destroy(t, map);
257 	}
258 	return (error);
259 }
260 
261 /*
262  * Destroy an ISA DMA map.
263  */
264 void
265 _isa_bus_dmamap_destroy(bus_dma_tag_t t, bus_dmamap_t map)
266 {
267 	struct powerpc_isa_dma_cookie *cookie = map->_dm_cookie;
268 
269 	/*
270 	 * Free any bounce pages this map might hold.
271 	 */
272 	if (cookie->id_flags & ID_HAS_BOUNCE)
273 		_isa_dma_free_bouncebuf(t, map);
274 
275 	free(cookie, M_DMAMAP);
276 	_bus_dmamap_destroy(t, map);
277 }
278 
279 /*
280  * Load an ISA DMA map with a linear buffer.
281  */
282 int
283 _isa_bus_dmamap_load(bus_dma_tag_t t, bus_dmamap_t map, void *buf,
284 	bus_size_t buflen, struct proc *p, int flags)
285 {
286 	struct powerpc_isa_dma_cookie *cookie = map->_dm_cookie;
287 	int error;
288 
289 	STAT_INCR(isa_dma_stats_loads);
290 
291 	/*
292 	 * Make sure that on error condition we return "no valid mappings."
293 	 */
294 	map->dm_mapsize = 0;
295 	map->dm_nsegs = 0;
296 
297 	/*
298 	 * Try to load the map the normal way.  If this errors out,
299 	 * and we can bounce, we will.
300 	 */
301 	error = _bus_dmamap_load(t, map, buf, buflen, p, flags);
302 	if (error == 0 ||
303 	    (error != 0 && (cookie->id_flags & ID_MIGHT_NEED_BOUNCE) == 0))
304 		return (error);
305 
306 	/*
307 	 * First attempt failed; bounce it.
308 	 */
309 
310 	STAT_INCR(isa_dma_stats_bounces);
311 
312 	/*
313 	 * Allocate bounce pages, if necessary.
314 	 */
315 	if ((cookie->id_flags & ID_HAS_BOUNCE) == 0) {
316 		error = _isa_dma_alloc_bouncebuf(t, map, buflen, flags);
317 		if (error)
318 			return (error);
319 	}
320 
321 	/*
322 	 * Cache a pointer to the caller's buffer and load the DMA map
323 	 * with the bounce buffer.
324 	 */
325 	cookie->id_origbuf = buf;
326 	cookie->id_origbuflen = buflen;
327 	cookie->id_buftype = ID_BUFTYPE_LINEAR;
328 	error = _bus_dmamap_load(t, map, cookie->id_bouncebuf, buflen,
329 	    p, flags);
330 	if (error) {
331 		/*
332 		 * Free the bounce pages, unless our resources
333 		 * are reserved for our exclusive use.
334 		 */
335 		if ((map->_dm_flags & BUS_DMA_ALLOCNOW) == 0)
336 			_isa_dma_free_bouncebuf(t, map);
337 		return (error);
338 	}
339 
340 	/* ...so _isa_bus_dmamap_sync() knows we're bouncing */
341 	cookie->id_flags |= ID_IS_BOUNCING;
342 	return (0);
343 }
344 
345 /*
346  * Like _isa_bus_dmamap_load(), but for mbufs.
347  */
348 int
349 _isa_bus_dmamap_load_mbuf(bus_dma_tag_t t, bus_dmamap_t map, struct mbuf *m0,
350 	int flags)
351 {
352 	struct powerpc_isa_dma_cookie *cookie = map->_dm_cookie;
353 	int error;
354 
355 	/*
356 	 * Make sure that on error condition we return "no valid mappings."
357 	 */
358 	map->dm_mapsize = 0;
359 	map->dm_nsegs = 0;
360 
361 #ifdef DIAGNOSTIC
362 	if ((m0->m_flags & M_PKTHDR) == 0)
363 		panic("_isa_bus_dmamap_load_mbuf: no packet header");
364 #endif
365 
366 	if (m0->m_pkthdr.len > map->_dm_size)
367 		return (EINVAL);
368 
369 	/*
370 	 * Try to load the map the normal way.  If this errors out,
371 	 * and we can bounce, we will.
372 	 */
373 	error = _bus_dmamap_load_mbuf(t, map, m0, flags);
374 	if (error == 0 ||
375 	    (error != 0 && (cookie->id_flags & ID_MIGHT_NEED_BOUNCE) == 0))
376 		return (error);
377 
378 	/*
379 	 * First attempt failed; bounce it.
380 	 */
381 
382 	STAT_INCR(isa_dma_stats_bounces);
383 
384 	/*
385 	 * Allocate bounce pages, if necessary.
386 	 */
387 	if ((cookie->id_flags & ID_HAS_BOUNCE) == 0) {
388 		error = _isa_dma_alloc_bouncebuf(t, map, m0->m_pkthdr.len,
389 		    flags);
390 		if (error)
391 			return (error);
392 	}
393 
394 	/*
395 	 * Cache a pointer to the caller's buffer and load the DMA map
396 	 * with the bounce buffer.
397 	 */
398 	cookie->id_origbuf = m0;
399 	cookie->id_origbuflen = m0->m_pkthdr.len;	/* not really used */
400 	cookie->id_buftype = ID_BUFTYPE_MBUF;
401 	error = _bus_dmamap_load(t, map, cookie->id_bouncebuf,
402 	    m0->m_pkthdr.len, NULL, flags);
403 	if (error) {
404 		/*
405 		 * Free the bounce pages, unless our resources
406 		 * are reserved for our exclusive use.
407 		 */
408 		if ((map->_dm_flags & BUS_DMA_ALLOCNOW) == 0)
409 			_isa_dma_free_bouncebuf(t, map);
410 		return (error);
411 	}
412 
413 	/* ...so _isa_bus_dmamap_sync() knows we're bouncing */
414 	cookie->id_flags |= ID_IS_BOUNCING;
415 	return (0);
416 }
417 
418 /*
419  * Like _isa_bus_dmamap_load(), but for uios.
420  */
421 int
422 _isa_bus_dmamap_load_uio(bus_dma_tag_t t, bus_dmamap_t map,
423 	struct uio *uio, int flags)
424 {
425 
426 	panic("_isa_bus_dmamap_load_uio: not implemented");
427 }
428 
429 /*
430  * Like _isa_bus_dmamap_load(), but for raw memory allocated with
431  * bus_dmamem_alloc().
432  */
433 int
434 _isa_bus_dmamap_load_raw(bus_dma_tag_t t, bus_dmamap_t map,
435 	bus_dma_segment_t *segs, int nsegs, bus_size_t size, int flags)
436 {
437 
438 	panic("_isa_bus_dmamap_load_raw: not implemented");
439 }
440 
441 /*
442  * Unload an ISA DMA map.
443  */
444 void
445 _isa_bus_dmamap_unload(bus_dma_tag_t t, bus_dmamap_t map)
446 {
447 	struct powerpc_isa_dma_cookie *cookie = map->_dm_cookie;
448 
449 	/*
450 	 * If we have bounce pages, free them, unless they're
451 	 * reserved for our exclusive use.
452 	 */
453 	if ((cookie->id_flags & ID_HAS_BOUNCE) &&
454 	    (map->_dm_flags & BUS_DMA_ALLOCNOW) == 0)
455 		_isa_dma_free_bouncebuf(t, map);
456 
457 	cookie->id_flags &= ~ID_IS_BOUNCING;
458 	cookie->id_buftype = ID_BUFTYPE_INVALID;
459 
460 	/*
461 	 * Do the generic bits of the unload.
462 	 */
463 	_bus_dmamap_unload(t, map);
464 }
465 
466 /*
467  * Synchronize an ISA DMA map.
468  */
469 void
470 _isa_bus_dmamap_sync(bus_dma_tag_t t, bus_dmamap_t map, bus_addr_t offset,
471 	bus_size_t len, int ops)
472 {
473 	struct powerpc_isa_dma_cookie *cookie = map->_dm_cookie;
474 
475 	/*
476 	 * Mixing PRE and POST operations is not allowed.
477 	 */
478 	if ((ops & (BUS_DMASYNC_PREREAD|BUS_DMASYNC_PREWRITE)) != 0 &&
479 	    (ops & (BUS_DMASYNC_POSTREAD|BUS_DMASYNC_POSTWRITE)) != 0)
480 		panic("_isa_bus_dmamap_sync: mix PRE and POST");
481 
482 #ifdef DIAGNOSTIC
483 	if ((ops & (BUS_DMASYNC_PREWRITE|BUS_DMASYNC_POSTREAD)) != 0) {
484 		if (offset >= map->dm_mapsize)
485 			panic("_isa_bus_dmamap_sync: bad offset");
486 		if (len == 0 || (offset + len) > map->dm_mapsize)
487 			panic("_isa_bus_dmamap_sync: bad length");
488 	}
489 #endif
490 
491 	/*
492 	 * If we're not bouncing, just return; nothing to do.
493 	 */
494 	if ((cookie->id_flags & ID_IS_BOUNCING) == 0)
495 		return;
496 
497 	switch (cookie->id_buftype) {
498 	case ID_BUFTYPE_LINEAR:
499 		/*
500 		 * Nothing to do for pre-read.
501 		 */
502 
503 		if (ops & BUS_DMASYNC_PREWRITE) {
504 			/*
505 			 * Copy the caller's buffer to the bounce buffer.
506 			 */
507 			memcpy((char *)cookie->id_bouncebuf + offset,
508 			    (char *)cookie->id_origbuf + offset, len);
509 		}
510 
511 		if (ops & BUS_DMASYNC_POSTREAD) {
512 			/*
513 			 * Copy the bounce buffer to the caller's buffer.
514 			 */
515 			memcpy((char *)cookie->id_origbuf + offset,
516 			    (char *)cookie->id_bouncebuf + offset, len);
517 		}
518 
519 		/*
520 		 * Nothing to do for post-write.
521 		 */
522 		break;
523 
524 	case ID_BUFTYPE_MBUF:
525 	    {
526 		struct mbuf *m, *m0 = cookie->id_origbuf;
527 		bus_size_t minlen, moff;
528 
529 		/*
530 		 * Nothing to do for pre-read.
531 		 */
532 
533 		if (ops & BUS_DMASYNC_PREWRITE) {
534 			/*
535 			 * Copy the caller's buffer to the bounce buffer.
536 			 */
537 			m_copydata(m0, offset, len,
538 			    (char *)cookie->id_bouncebuf + offset);
539 		}
540 
541 		if (ops & BUS_DMASYNC_POSTREAD) {
542 			/*
543 			 * Copy the bounce buffer to the caller's buffer.
544 			 */
545 			for (moff = offset, m = m0; m != NULL && len != 0;
546 			    m = m->m_next) {
547 				/* Find the beginning mbuf. */
548 				if (moff >= m->m_len) {
549 					moff -= m->m_len;
550 					continue;
551 				}
552 
553 				/*
554 				 * Now at the first mbuf to sync; nail
555 				 * each one until we have exhausted the
556 				 * length.
557 				 */
558 				minlen = len < m->m_len - moff ?
559 				    len : m->m_len - moff;
560 
561 				memcpy(mtod(m, char *) + moff,
562 				    (char *)cookie->id_bouncebuf + offset,
563 				    minlen);
564 
565 				moff = 0;
566 				len -= minlen;
567 				offset += minlen;
568 			}
569 		}
570 
571 		/*
572 		 * Nothing to do for post-write.
573 		 */
574 		break;
575 	    }
576 
577 	case ID_BUFTYPE_UIO:
578 		panic("_isa_bus_dmamap_sync: ID_BUFTYPE_UIO");
579 		break;
580 
581 	case ID_BUFTYPE_RAW:
582 		panic("_isa_bus_dmamap_sync: ID_BUFTYPE_RAW");
583 		break;
584 
585 	case ID_BUFTYPE_INVALID:
586 		panic("_isa_bus_dmamap_sync: ID_BUFTYPE_INVALID");
587 		break;
588 
589 	default:
590 		printf("unknown buffer type %d\n", cookie->id_buftype);
591 		panic("_isa_bus_dmamap_sync");
592 	}
593 }
594 
595 /*
596  * Allocate memory safe for ISA DMA.
597  */
598 int
599 _isa_bus_dmamem_alloc(bus_dma_tag_t t, bus_size_t size, bus_size_t alignment,
600 	bus_size_t boundary, bus_dma_segment_t *segs, int nsegs, int *rsegs,
601 	int flags)
602 {
603 	paddr_t high, avail_end = 0;
604 	int bank;
605 
606 	for (bank = 0; bank < vm_nphysseg; bank++) {
607 		if (avail_end < vm_physmem[bank].avail_end << PGSHIFT)
608 			avail_end = vm_physmem[bank].avail_end << PGSHIFT;
609 	}
610 
611 	if (avail_end > ISA_DMA_BOUNCE_THRESHOLD)
612 		high = trunc_page(ISA_DMA_BOUNCE_THRESHOLD);
613 	else
614 		high = trunc_page(avail_end);
615 	return (_bus_dmamem_alloc_range(t, size, alignment, boundary,
616 	    segs, nsegs, rsegs, flags, 0, high));
617 }
618 
619 /**********************************************************************
620  * ISA DMA utility functions
621  **********************************************************************/
622 
623 int
624 _isa_dma_alloc_bouncebuf(bus_dma_tag_t t, bus_dmamap_t map, bus_size_t size,
625 	int flags)
626 {
627 	struct powerpc_isa_dma_cookie *cookie = map->_dm_cookie;
628 	int error = 0;
629 
630 	cookie->id_bouncebuflen = round_page(size);
631 	error = _isa_bus_dmamem_alloc(t, cookie->id_bouncebuflen,
632 	    PAGE_SIZE, map->_dm_boundary, cookie->id_bouncesegs,
633 	    map->_dm_segcnt, &cookie->id_nbouncesegs, flags);
634 	if (error)
635 		goto out;
636 	error = _bus_dmamem_map(t, cookie->id_bouncesegs,
637 	    cookie->id_nbouncesegs, cookie->id_bouncebuflen,
638 	    (void **)&cookie->id_bouncebuf, flags);
639 
640  out:
641 	if (error) {
642 		_bus_dmamem_free(t, cookie->id_bouncesegs,
643 		    cookie->id_nbouncesegs);
644 		cookie->id_bouncebuflen = 0;
645 		cookie->id_nbouncesegs = 0;
646 	} else {
647 		cookie->id_flags |= ID_HAS_BOUNCE;
648 		STAT_INCR(isa_dma_stats_nbouncebufs);
649 	}
650 
651 	return (error);
652 }
653 
654 void
655 _isa_dma_free_bouncebuf(bus_dma_tag_t t, bus_dmamap_t map)
656 {
657 	struct powerpc_isa_dma_cookie *cookie = map->_dm_cookie;
658 
659 	STAT_DECR(isa_dma_stats_nbouncebufs);
660 
661 	_bus_dmamem_unmap(t, cookie->id_bouncebuf,
662 	    cookie->id_bouncebuflen);
663 	_bus_dmamem_free(t, cookie->id_bouncesegs,
664 	    cookie->id_nbouncesegs);
665 	cookie->id_bouncebuflen = 0;
666 	cookie->id_nbouncesegs = 0;
667 	cookie->id_flags &= ~ID_HAS_BOUNCE;
668 }
669