aboutsummaryrefslogtreecommitdiffstats
path: root/sys/ia64/ia64/busdma_machdep.c
blob: 7e7366a3d513c8807a1b1e1aab9c73d47684b93b (plain) (blame)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
448
449
450
451
452
453
454
455
456
457
458
459
460
461
462
463
464
465
466
467
468
469
470
471
472
473
474
475
476
477
478
479
480
481
482
483
484
485
486
487
488
489
490
491
492
493
494
495
496
497
498
499
500
501
502
503
504
505
506
507
508
509
510
511
512
513
514
515
516
517
518
519
520
521
522
523
524
525
526
527
528
529
530
531
532
533
534
535
536
537
538
539
540
541
542
543
544
545
546
547
548
549
550
551
552
553
554
555
556
557
558
559
560
561
562
563
564
565
566
567
568
569
570
571
572
573
574
575
576
577
578
579
580
581
582
583
584
585
586
587
588
589
590
591
592
593
594
595
596
597
598
599
600
601
602
603
604
605
606
607
608
609
610
611
612
613
614
615
616
617
618
619
620
621
622
623
624
625
626
627
628
629
630
631
632
633
634
635
636
637
638
639
640
641
642
643
644
645
646
647
648
649
650
651
652
653
654
655
656
657
658
659
660
661
662
663
664
665
666
667
668
669
670
671
672
673
674
675
676
677
678
679
680
681
682
683
684
685
686
687
688
689
690
691
692
693
694
695
696
697
698
699
700
701
702
703
704
705
706
707
708
709
710
711
712
713
714
715
716
717
718
719
720
721
722
723
724
725
726
727
728
729
730
731
732
733
734
735
736
737
738
739
740
741
742
743
744
745
746
747
748
749
750
751
752
753
754
755
756
757
758
759
760
761
762
763
764
765
766
767
768
769
770
771
772
773
774
775
776
777
778
779
780
781
782
783
784
785
786
787
788
789
790
791
792
793
794
795
796
797
798
799
800
801
802
803
804
805
806
807
808
809
810
811
812
813
814
815
816
817
818
819
820
821
822
823
824
825
826
827
828
829
830
831
832
833
834
835
836
837
838
839
840
841
842
843
844
845
846
847
848
849
850
851
852
853
854
855
856
857
858
859
860
861
862
863
864
865
866
867
868
869
870
871
872
873
874
875
876
877
878
879
880
881
882
883
884
885
886
887
888
889
890
891
892
893
894
895
896
897
898
899
900
901
902
903
904
905
906
907
908
909
910
911
912
913
914
915
916
917
918
919
920
921
922
923
924
925
926
927
928
929
930
931
932
933
934
935
936
937
938
939
940
941
942
943
944
945
946
947
948
949
950
951
952
953
954
955
956
957
958
959
960
961
962
963
964
965
966
967
968
969
970
971
972
973
974
975
976
977
978
979
980
981
982
983
984
985
986
987
988
989
990
991
992
993
994
995
996
997
998
999
1000
1001
1002
1003
1004
1005
/*-
 * Copyright (c) 1997 Justin T. Gibbs.
 * 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,
 *    without modification, immediately at the beginning of the file.
 * 2. The name of the author may not be used to endorse or promote products
 *    derived from this software without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR 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 AUTHOR 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>
__FBSDID("$FreeBSD$");

#include <sys/param.h>
#include <sys/systm.h>
#include <sys/kernel.h>
#include <sys/malloc.h>
#include <sys/mbuf.h>
#include <sys/lock.h>
#include <sys/mutex.h>
#include <sys/bus.h>
#include <sys/interrupt.h>
#include <sys/proc.h>
#include <sys/uio.h>
#include <sys/sysctl.h>

#include <vm/vm.h>
#include <vm/vm_page.h>
#include <vm/vm_map.h>

#include <machine/atomic.h>
#include <machine/bus.h>
#include <machine/md_var.h>

#define MAX_BPAGES 256

struct bus_dma_tag {
	bus_dma_tag_t	  parent;
	bus_size_t	  alignment;
	bus_size_t	  boundary;
	bus_addr_t	  lowaddr;
	bus_addr_t	  highaddr;
	bus_dma_filter_t *filter;
	void		 *filterarg;
	bus_size_t	  maxsize;
	u_int		  nsegments;
	bus_size_t	  maxsegsz;
	int		  flags;
	int		  ref_count;
	int		  map_count;
	bus_dma_lock_t	 *lockfunc;
	void		 *lockfuncarg;
	bus_dma_segment_t *segments;
};

struct bounce_page {
	vm_offset_t	vaddr;		/* kva of bounce buffer */
	bus_addr_t	busaddr;	/* Physical address */
	vm_offset_t	datavaddr;	/* kva of client data */
	bus_size_t	datacount;	/* client data count */
	STAILQ_ENTRY(bounce_page) links;
};

int busdma_swi_pending;

static struct mtx bounce_lock;
static STAILQ_HEAD(bp_list, bounce_page) bounce_page_list;
static int free_bpages;
static int reserved_bpages;
static int active_bpages;
static int total_bpages;
static int total_bounced;
static int total_deferred;

SYSCTL_NODE(_hw, OID_AUTO, busdma, CTLFLAG_RD, 0, "Busdma parameters");
SYSCTL_INT(_hw_busdma, OID_AUTO, free_bpages, CTLFLAG_RD, &free_bpages, 0,
	   "Free bounce pages");
SYSCTL_INT(_hw_busdma, OID_AUTO, reserved_bpages, CTLFLAG_RD, &reserved_bpages,
	   0, "Reserved bounce pages");
SYSCTL_INT(_hw_busdma, OID_AUTO, active_bpages, CTLFLAG_RD, &active_bpages, 0,
	   "Active bounce pages");
SYSCTL_INT(_hw_busdma, OID_AUTO, total_bpages, CTLFLAG_RD, &total_bpages, 0,
	   "Total bounce pages");
SYSCTL_INT(_hw_busdma, OID_AUTO, total_bounced, CTLFLAG_RD, &total_bounced, 0,
	   "Total bounce requests");
SYSCTL_INT(_hw_busdma, OID_AUTO, total_deferred, CTLFLAG_RD, &total_deferred, 0,
	   "Total bounce requests that were deferred");

struct bus_dmamap {
	struct bp_list	       bpages;
	int		       pagesneeded;
	int		       pagesreserved;
	bus_dma_tag_t	       dmat;
	void		      *buf;		/* unmapped buffer pointer */
	bus_size_t	       buflen;		/* unmapped buffer length */
	bus_dmamap_callback_t *callback;
	void		      *callback_arg;
	STAILQ_ENTRY(bus_dmamap) links;
};

static STAILQ_HEAD(, bus_dmamap) bounce_map_waitinglist;
static STAILQ_HEAD(, bus_dmamap) bounce_map_callbacklist;
static struct bus_dmamap nobounce_dmamap;

static void init_bounce_pages(void *dummy);
static int alloc_bounce_pages(bus_dma_tag_t dmat, u_int numpages);
static int reserve_bounce_pages(bus_dma_tag_t dmat, bus_dmamap_t map,
				int commit);
static bus_addr_t add_bounce_page(bus_dma_tag_t dmat, bus_dmamap_t map,
				   vm_offset_t vaddr, bus_size_t size);
static void free_bounce_page(bus_dma_tag_t dmat, struct bounce_page *bpage);
static __inline int run_filter(bus_dma_tag_t dmat, bus_addr_t paddr,
			       bus_size_t len);

/*
 * Return true if a match is made.
 *
 * To find a match walk the chain of bus_dma_tag_t's looking for 'paddr'.
 *
 * If paddr is within the bounds of the dma tag then call the filter callback
 * to check for a match, if there is no filter callback then assume a match.
 */
static __inline int
run_filter(bus_dma_tag_t dmat, bus_addr_t paddr, bus_size_t len)
{
	bus_size_t bndy;
	int retval;

	retval = 0;
	bndy = dmat->boundary;

	do {
		if (((paddr > dmat->lowaddr && paddr <= dmat->highaddr)
		 || ((paddr & (dmat->alignment - 1)) != 0)
		 || ((paddr & bndy) != ((paddr + len) & bndy)))
		 && (dmat->filter == NULL
		  || (*dmat->filter)(dmat->filterarg, paddr) != 0))
			retval = 1;

		dmat = dmat->parent;		
	} while (retval == 0 && dmat != NULL);
	return (retval);
}

/*
 * Convenience function for manipulating driver locks from busdma (during
 * busdma_swi, for example).  Drivers that don't provide their own locks
 * should specify &Giant to dmat->lockfuncarg.  Drivers that use their own
 * non-mutex locking scheme don't have to use this at all.
 */
void
busdma_lock_mutex(void *arg, bus_dma_lock_op_t op)
{
	struct mtx *dmtx;

	dmtx = (struct mtx *)arg;
	switch (op) {
	case BUS_DMA_LOCK:
		mtx_lock(dmtx);
		break;
	case BUS_DMA_UNLOCK:
		mtx_unlock(dmtx);
		break;
	default:
		panic("Unknown operation 0x%x for busdma_lock_mutex!", op);
	}
}

/*
 * dflt_lock should never get called.  It gets put into the dma tag when
 * lockfunc == NULL, which is only valid if the maps that are associated
 * with the tag are meant to never be defered.
 * XXX Should have a way to identify which driver is responsible here.
 */
static void
dflt_lock(void *arg, bus_dma_lock_op_t op)
{
	panic("driver error: busdma dflt_lock called");
}

#define BUS_DMA_MIN_ALLOC_COMP BUS_DMA_BUS4
/*
 * Allocate a device specific dma_tag.
 */
int
bus_dma_tag_create(bus_dma_tag_t parent, bus_size_t alignment,
		   bus_size_t boundary, bus_addr_t lowaddr,
		   bus_addr_t highaddr, bus_dma_filter_t *filter,
		   void *filterarg, bus_size_t maxsize, int nsegments,
		   bus_size_t maxsegsz, int flags, bus_dma_lock_t *lockfunc,
		   void *lockfuncarg, bus_dma_tag_t *dmat)
{
	bus_dma_tag_t newtag;
	int error = 0;

	/* Basic sanity checking */
	if (boundary != 0 && boundary < maxsegsz)
		maxsegsz = boundary;

	/* Return a NULL tag on failure */
	*dmat = NULL;

	newtag = (bus_dma_tag_t)malloc(sizeof(*newtag), M_DEVBUF, M_NOWAIT);
	if (newtag == NULL)
		return (ENOMEM);

	newtag->parent = parent;
	newtag->alignment = alignment;
	newtag->boundary = boundary;
	newtag->lowaddr = trunc_page(lowaddr) + (PAGE_SIZE - 1);
	newtag->highaddr = trunc_page(highaddr) + (PAGE_SIZE - 1);
	newtag->filter = filter;
	newtag->filterarg = filterarg;
	newtag->maxsize = maxsize;
	newtag->nsegments = nsegments;
	newtag->maxsegsz = maxsegsz;
	newtag->flags = flags;
	newtag->ref_count = 1; /* Count ourself */
	newtag->map_count = 0;
	if (lockfunc != NULL) {
		newtag->lockfunc = lockfunc;
		newtag->lockfuncarg = lockfuncarg;
	} else {
		newtag->lockfunc = dflt_lock;
		newtag->lockfuncarg = NULL;
	}
	newtag->segments = NULL;

	/* Take into account any restrictions imposed by our parent tag */
	if (parent != NULL) {
		newtag->lowaddr = MIN(parent->lowaddr, newtag->lowaddr);
		newtag->highaddr = MAX(parent->highaddr, newtag->highaddr);
		if (newtag->boundary == 0)
			newtag->boundary = parent->boundary;
		else if (parent->boundary != 0)
			newtag->boundary = MIN(parent->boundary,
					       newtag->boundary);
		if (newtag->filter == NULL) {
			/*
			 * Short circuit looking at our parent directly
			 * since we have encapsulated all of its information
			 */
			newtag->filter = parent->filter;
			newtag->filterarg = parent->filterarg;
			newtag->parent = parent->parent;
		}
		if (newtag->parent != NULL)
			atomic_add_int(&parent->ref_count, 1);
	}

	if (newtag->lowaddr < ptoa(Maxmem) && (flags & BUS_DMA_ALLOCNOW) != 0) {
		/* Must bounce */

		if (ptoa(total_bpages) < maxsize) {
			int pages;

			pages = atop(maxsize) - total_bpages;

			/* Add pages to our bounce pool */
			if (alloc_bounce_pages(newtag, pages) < pages)
				error = ENOMEM;
		}
		/* Performed initial allocation */
		newtag->flags |= BUS_DMA_MIN_ALLOC_COMP;
	}
	
	if (error != 0) {
		free(newtag, M_DEVBUF);
	} else {
		*dmat = newtag;
	}
	return (error);
}

int
bus_dma_tag_destroy(bus_dma_tag_t dmat)
{
	if (dmat != NULL) {

		if (dmat->map_count != 0)
			return (EBUSY);

		while (dmat != NULL) {
			bus_dma_tag_t parent;

			parent = dmat->parent;
			atomic_subtract_int(&dmat->ref_count, 1);
			if (dmat->ref_count == 0) {
				if (dmat->segments != NULL)
					free(dmat->segments, M_DEVBUF);
				free(dmat, M_DEVBUF);
				/*
				 * Last reference count, so
				 * release our reference
				 * count on our parent.
				 */
				dmat = parent;
			} else
				dmat = NULL;
		}
	}
	return (0);
}

/*
 * Allocate a handle for mapping from kva/uva/physical
 * address space into bus device space.
 */
int
bus_dmamap_create(bus_dma_tag_t dmat, int flags, bus_dmamap_t *mapp)
{
	int error;

	error = 0;

	if (dmat->segments == NULL) {
		dmat->segments = (bus_dma_segment_t *)malloc(
		    sizeof(bus_dma_segment_t) * dmat->nsegments, M_DEVBUF,
		    M_NOWAIT);
		if (dmat->segments == NULL)
			return (ENOMEM);
	}

	/*
	 * Bouncing might be required if the driver asks for an active
	 * exclusion region, a data alignment that is stricter than 1, and/or
	 * an active address boundary.
	 */
	if (dmat->lowaddr < ptoa(Maxmem)) {
		/* Must bounce */
		int maxpages;

		*mapp = (bus_dmamap_t)malloc(sizeof(**mapp), M_DEVBUF,
					     M_NOWAIT | M_ZERO);
		if (*mapp == NULL)
			return (ENOMEM);

		/* Initialize the new map */
		STAILQ_INIT(&((*mapp)->bpages));

		/*
		 * Attempt to add pages to our pool on a per-instance
		 * basis up to a sane limit.
		 */
		maxpages = MIN(MAX_BPAGES, Maxmem - atop(dmat->lowaddr));
		if ((dmat->flags & BUS_DMA_MIN_ALLOC_COMP) == 0
		 || (dmat->map_count > 0 && total_bpages < maxpages)) {
			int pages;

			pages = MAX(atop(dmat->maxsize), 1);
			pages = MIN(maxpages - total_bpages, pages);
			if (alloc_bounce_pages(dmat, pages) < pages)
				error = ENOMEM;

			if ((dmat->flags & BUS_DMA_MIN_ALLOC_COMP) == 0) {
				if (error == 0)
					dmat->flags |= BUS_DMA_MIN_ALLOC_COMP;
			} else {
				error = 0;
			}
		}
	} else {
		*mapp = NULL;
	}
	if (error == 0)
		dmat->map_count++;
	return (error);
}

/*
 * Destroy a handle for mapping from kva/uva/physical
 * address space into bus device space.
 */
int
bus_dmamap_destroy(bus_dma_tag_t dmat, bus_dmamap_t map)
{

	if (map != NULL && map != &nobounce_dmamap) {
		if (STAILQ_FIRST(&map->bpages) != NULL)
			return (EBUSY);
		free(map, M_DEVBUF);
	}
	dmat->map_count--;
	return (0);
}


/*
 * Allocate a piece of memory that can be efficiently mapped into
 * bus device space based on the constraints lited in the dma tag.
 * A dmamap to for use with dmamap_load is also allocated.
 */
int
bus_dmamem_alloc(bus_dma_tag_t dmat, void** vaddr, int flags,
		 bus_dmamap_t *mapp)
{
	int mflags;

	if (flags & BUS_DMA_NOWAIT)
		mflags = M_NOWAIT;
	else
		mflags = M_WAITOK;

	/* If we succeed, no mapping/bouncing will be required */
	*mapp = NULL;

	if (dmat->segments == NULL) {
		dmat->segments = (bus_dma_segment_t *)malloc(
		    sizeof(bus_dma_segment_t) * dmat->nsegments, M_DEVBUF,
		    mflags);
		if (dmat->segments == NULL)
			return (ENOMEM);
	}
	if (flags & BUS_DMA_ZERO)
		mflags |= M_ZERO;

	/* 
	 * XXX:
	 * (dmat->alignment < dmat->maxsize) is just a quick hack; the exact
	 * alignment guarantees of malloc need to be nailed down, and the
	 * code below should be rewritten to take that into account.
	 *
	 * In the meantime, we'll warn the user if malloc gets it wrong.
	 */
	if ((dmat->maxsize <= PAGE_SIZE) &&
	   (dmat->alignment < dmat->maxsize) &&
	    dmat->lowaddr >= ptoa(Maxmem)) {
		*vaddr = malloc(dmat->maxsize, M_DEVBUF, mflags);
	} else {
		/*
		 * XXX Use Contigmalloc until it is merged into this facility
		 *     and handles multi-seg allocations.  Nobody is doing
		 *     multi-seg allocations yet though.
		 * XXX Certain AGP hardware does.
		 */
		*vaddr = contigmalloc(dmat->maxsize, M_DEVBUF, mflags,
		    0ul, dmat->lowaddr, dmat->alignment? dmat->alignment : 1ul,
		    dmat->boundary);
	}
	if (*vaddr == NULL)
		return (ENOMEM);
	else if ((uintptr_t)*vaddr & (dmat->alignment - 1))
		printf("bus_dmamem_alloc failed to align memory properly.\n");
	return (0);
}

/*
 * Free a piece of memory and it's allociated dmamap, that was allocated
 * via bus_dmamem_alloc.  Make the same choice for free/contigfree.
 */
void
bus_dmamem_free(bus_dma_tag_t dmat, void *vaddr, bus_dmamap_t map)
{
	/*
	 * dmamem does not need to be bounced, so the map should be
	 * NULL
	 */
	if (map != NULL)
		panic("bus_dmamem_free: Invalid map freed\n");
	if ((dmat->maxsize <= PAGE_SIZE) &&
	   (dmat->alignment < dmat->maxsize) &&
	    dmat->lowaddr >= ptoa(Maxmem))
		free(vaddr, M_DEVBUF);
	else {
		contigfree(vaddr, dmat->maxsize, M_DEVBUF);
	}
}

/*
 * 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.
 */
static int
_bus_dmamap_load_buffer(bus_dma_tag_t dmat,
			bus_dmamap_t map,
			void *buf, bus_size_t buflen,
			struct thread *td,
			int flags,
			bus_addr_t *lastaddrp,
			bus_dma_segment_t *segs,
			int *segp,
			int first)
{
	bus_size_t sgsize;
	bus_addr_t curaddr, lastaddr, baddr, bmask;
	vm_offset_t vaddr;
	bus_addr_t paddr;
	int seg;
	pmap_t pmap;

	if (map == NULL)
		map = &nobounce_dmamap;

	if (td != NULL)
		pmap = vmspace_pmap(td->td_proc->p_vmspace);
	else
		pmap = NULL;

	if ((dmat->lowaddr < ptoa(Maxmem) || dmat->boundary > 0 ||
	    dmat->alignment > 1) && map != &nobounce_dmamap &&
	    map->pagesneeded == 0) {
		vm_offset_t vendaddr;

		/*
		 * Count the number of bounce pages
		 * needed in order to complete this transfer
		 */
		vaddr = trunc_page((vm_offset_t)buf);
		vendaddr = (vm_offset_t)buf + buflen;

		while (vaddr < vendaddr) {
			if (pmap != NULL)
				paddr = pmap_extract(pmap, vaddr);
			else
				paddr = pmap_kextract(vaddr);
			if (run_filter(dmat, paddr, 0) != 0)
				map->pagesneeded++;
			vaddr += PAGE_SIZE;
		}
	}

	vaddr = (vm_offset_t)buf;

	/* Reserve Necessary Bounce Pages */
	if (map->pagesneeded != 0) {
		mtx_lock(&bounce_lock);
		if (flags & BUS_DMA_NOWAIT) {
			if (reserve_bounce_pages(dmat, map, 0) != 0) {
				mtx_unlock(&bounce_lock);
				return (ENOMEM);
			}
		} else {
			if (reserve_bounce_pages(dmat, map, 1) != 0) {
				/* Queue us for resources */
				map->dmat = dmat;
				map->buf = buf;
				map->buflen = buflen;
				STAILQ_INSERT_TAIL(&bounce_map_waitinglist,
				    map, links);
				mtx_unlock(&bounce_lock);
				return (EINPROGRESS);
			}
		}
		mtx_unlock(&bounce_lock);
	}

	lastaddr = *lastaddrp;
	bmask = ~(dmat->boundary - 1);

	for (seg = *segp; buflen > 0 ; ) {
		/*
		 * Get the physical address for this segment.
		 */
		if (pmap)
			curaddr = pmap_extract(pmap, vaddr);
		else
			curaddr = pmap_kextract(vaddr);

		/*
		 * Compute the segment size, and adjust counts.
		 */
		sgsize = PAGE_SIZE - ((u_long)curaddr & PAGE_MASK);
		if (sgsize > dmat->maxsegsz)
			sgsize = dmat->maxsegsz;
		if (buflen < sgsize)
			sgsize = buflen;

		/*
		 * Make sure we don't cross any boundaries.
		 */
		if (dmat->boundary > 0) {
			baddr = (curaddr + dmat->boundary) & bmask;
			if (sgsize > (baddr - curaddr))
				sgsize = (baddr - curaddr);
		}

		if (map->pagesneeded != 0 && run_filter(dmat, curaddr, sgsize))
			curaddr = add_bounce_page(dmat, map, vaddr, sgsize);

		/*
		 * Insert chunk into a segment, coalescing with
		 * previous segment if possible.
		 */
		if (first) {
			segs[seg].ds_addr = curaddr;
			segs[seg].ds_len = sgsize;
			first = 0;
		} else {
			if (curaddr == lastaddr &&
			    (segs[seg].ds_len + sgsize) <= dmat->maxsegsz &&
			    (dmat->boundary == 0 ||
			     (segs[seg].ds_addr & bmask) == (curaddr & bmask)))
				segs[seg].ds_len += sgsize;
			else {
				if (++seg >= dmat->nsegments)
					break;
				segs[seg].ds_addr = curaddr;
				segs[seg].ds_len = sgsize;
			}
		}

		lastaddr = curaddr + sgsize;
		vaddr += sgsize;
		buflen -= sgsize;
	}

	*segp = seg;
	*lastaddrp = lastaddr;

	/*
	 * Did we fit?
	 */
	return (buflen != 0 ? EFBIG : 0); /* XXX better return value here? */
}

/*
 * Map the buffer buf into bus space using the dmamap map.
 */
int
bus_dmamap_load(bus_dma_tag_t dmat, bus_dmamap_t map, void *buf,
		bus_size_t buflen, bus_dmamap_callback_t *callback,
		void *callback_arg, int flags)
{
	bus_addr_t		lastaddr = 0;
	int			error, nsegs = 0;

	if (map != NULL) {
		flags |= BUS_DMA_WAITOK;
		map->callback = callback;
		map->callback_arg = callback_arg;
	}

	error = _bus_dmamap_load_buffer(dmat, map, buf, buflen, NULL, flags,
	    &lastaddr, dmat->segments, &nsegs, 1);

	if (error == EINPROGRESS)
		return (error);

	if (error)
		(*callback)(callback_arg, dmat->segments, 0, error);
	else
		(*callback)(callback_arg, dmat->segments, nsegs + 1, 0);

	return (0);
}

/*
 * Like _bus_dmamap_load(), but for mbufs.
 */
int
bus_dmamap_load_mbuf(bus_dma_tag_t dmat, bus_dmamap_t map,
		     struct mbuf *m0,
		     bus_dmamap_callback2_t *callback, void *callback_arg,
		     int flags)
{
	int nsegs, error;

	M_ASSERTPKTHDR(m0);

	flags |= BUS_DMA_NOWAIT;
	nsegs = 0;
	error = 0;
	if (m0->m_pkthdr.len <= dmat->maxsize) {
		int first = 1;
		bus_addr_t lastaddr = 0;
		struct mbuf *m;

		for (m = m0; m != NULL && error == 0; m = m->m_next) {
			if (m->m_len > 0) {
				error = _bus_dmamap_load_buffer(dmat, map,
						m->m_data, m->m_len,
						NULL, flags, &lastaddr,
						dmat->segments, &nsegs, first);
				first = 0;
			}
		}
	} else {
		error = EINVAL;
	}

	if (error) {
		/* force "no valid mappings" in callback */
		(*callback)(callback_arg, dmat->segments, 0, 0, error);
	} else {
		(*callback)(callback_arg, dmat->segments, nsegs + 1,
		    m0->m_pkthdr.len, error);
	}
	return (error);
}

int
bus_dmamap_load_mbuf_sg(bus_dma_tag_t dmat, bus_dmamap_t map,
			struct mbuf *m0, bus_dma_segment_t *segs,
			int *nsegs, int flags)
{
	int error;

	M_ASSERTPKTHDR(m0);

	flags |= BUS_DMA_NOWAIT;
	*nsegs = 0;
	error = 0;
	if (m0->m_pkthdr.len <= dmat->maxsize) {
		int first = 1;
		bus_addr_t lastaddr = 0;
		struct mbuf *m;

		for (m = m0; m != NULL && error == 0; m = m->m_next) {
			if (m->m_len > 0) {
				error = _bus_dmamap_load_buffer(dmat, map,
						m->m_data, m->m_len,
						NULL, flags, &lastaddr,
						segs, nsegs, first);
				first = 0;
			}
		}
		++*nsegs;
	} else {
		error = EINVAL;
	}

	return (error);
}

/*
 * Like _bus_dmamap_load(), but for uios.
 */
int
bus_dmamap_load_uio(bus_dma_tag_t dmat, bus_dmamap_t map,
		    struct uio *uio,
		    bus_dmamap_callback2_t *callback, void *callback_arg,
		    int flags)
{
	bus_addr_t lastaddr;
	int nsegs, error, first, i;
	bus_size_t resid;
	struct iovec *iov;
	struct thread *td = NULL;

	flags |= BUS_DMA_NOWAIT;
	resid = uio->uio_resid;
	iov = uio->uio_iov;

	if (uio->uio_segflg == UIO_USERSPACE) {
		td = uio->uio_td;
		KASSERT(td != NULL,
			("bus_dmamap_load_uio: USERSPACE but no proc"));
	}

	nsegs = 0;
	error = 0;
	first = 1;
	for (i = 0; i < uio->uio_iovcnt && resid != 0 && !error; i++) {
		/*
		 * Now at the first iovec to load.  Load each iovec
		 * until we have exhausted the residual count.
		 */
		bus_size_t minlen =
			resid < iov[i].iov_len ? resid : iov[i].iov_len;
		caddr_t addr = (caddr_t) iov[i].iov_base;

		if (minlen > 0) {
			error = _bus_dmamap_load_buffer(dmat, map, addr,
			    minlen, td, flags, &lastaddr, dmat->segments,
			    &nsegs, first);
			first = 0;

			resid -= minlen;
		}
	}

	if (error) {
		/* force "no valid mappings" in callback */
		(*callback)(callback_arg, dmat->segments, 0, 0, error);
	} else {
		(*callback)(callback_arg, dmat->segments, nsegs + 1,
		    uio->uio_resid, error);
	}
	return (error);
}

/*
 * Release the mapping held by map.
 */
void
_bus_dmamap_unload(bus_dma_tag_t dmat, bus_dmamap_t map)
{
	struct bounce_page *bpage;

	while ((bpage = STAILQ_FIRST(&map->bpages)) != NULL) {
		STAILQ_REMOVE_HEAD(&map->bpages, links);
		free_bounce_page(dmat, bpage);
	}
}

void
_bus_dmamap_sync(bus_dma_tag_t dmat, bus_dmamap_t map, bus_dmasync_op_t op)
{
	struct bounce_page *bpage;

	if ((bpage = STAILQ_FIRST(&map->bpages)) != NULL) {
		/*
		 * Handle data bouncing.  We might also
		 * want to add support for invalidating
		 * the caches on broken hardware
		 */

		if (op & BUS_DMASYNC_PREWRITE) {
			while (bpage != NULL) {
				bcopy((void *)bpage->datavaddr,
				      (void *)bpage->vaddr,
				      bpage->datacount);
				bpage = STAILQ_NEXT(bpage, links);
			}
			total_bounced++;
		}

		if (op & BUS_DMASYNC_POSTREAD) {
			while (bpage != NULL) {
				bcopy((void *)bpage->vaddr,
				      (void *)bpage->datavaddr,
				      bpage->datacount);
				bpage = STAILQ_NEXT(bpage, links);
			}
			total_bounced++;
		}
	}
}

static void
init_bounce_pages(void *dummy __unused)
{

	free_bpages = 0;
	reserved_bpages = 0;
	active_bpages = 0;
	total_bpages = 0;
	STAILQ_INIT(&bounce_page_list);
	STAILQ_INIT(&bounce_map_waitinglist);
	STAILQ_INIT(&bounce_map_callbacklist);
	mtx_init(&bounce_lock, "bounce pages lock", NULL, MTX_DEF);
}
SYSINIT(bpages, SI_SUB_LOCK, SI_ORDER_ANY, init_bounce_pages, NULL);

static int
alloc_bounce_pages(bus_dma_tag_t dmat, u_int numpages)
{
	int count;

	count = 0;
	while (numpages > 0) {
		struct bounce_page *bpage;

		bpage = (struct bounce_page *)malloc(sizeof(*bpage), M_DEVBUF,
						     M_NOWAIT | M_ZERO);

		if (bpage == NULL)
			break;
		bpage->vaddr = (vm_offset_t)contigmalloc(PAGE_SIZE, M_DEVBUF,
							 M_NOWAIT, 0ul,
							 dmat->lowaddr,
							 PAGE_SIZE,
							 dmat->boundary);
		if (bpage->vaddr == 0) {
			free(bpage, M_DEVBUF);
			break;
		}
		bpage->busaddr = pmap_kextract(bpage->vaddr);
		mtx_lock(&bounce_lock);
		STAILQ_INSERT_TAIL(&bounce_page_list, bpage, links);
		total_bpages++;
		free_bpages++;
		mtx_unlock(&bounce_lock);
		count++;
		numpages--;
	}
	return (count);
}

static int
reserve_bounce_pages(bus_dma_tag_t dmat, bus_dmamap_t map, int commit)
{
	int pages;

	mtx_assert(&bounce_lock, MA_OWNED);
	pages = MIN(free_bpages, map->pagesneeded - map->pagesreserved);
	if (commit == 0 && map->pagesneeded > (map->pagesreserved + pages))
		return (map->pagesneeded - (map->pagesreserved + pages));
	free_bpages -= pages;
	reserved_bpages += pages;
	map->pagesreserved += pages;
	pages = map->pagesneeded - map->pagesreserved;

	return (pages);
}

static bus_addr_t
add_bounce_page(bus_dma_tag_t dmat, bus_dmamap_t map, vm_offset_t vaddr,
		bus_size_t size)
{
	struct bounce_page *bpage;

	KASSERT(map != NULL && map != &nobounce_dmamap,
	    ("add_bounce_page: bad map %p", map));

	if (map->pagesneeded == 0)
		panic("add_bounce_page: map doesn't need any pages");
	map->pagesneeded--;

	if (map->pagesreserved == 0)
		panic("add_bounce_page: map doesn't need any pages");
	map->pagesreserved--;

	mtx_lock(&bounce_lock);
	bpage = STAILQ_FIRST(&bounce_page_list);
	if (bpage == NULL)
		panic("add_bounce_page: free page list is empty");

	STAILQ_REMOVE_HEAD(&bounce_page_list, links);
	reserved_bpages--;
	active_bpages++;
	mtx_unlock(&bounce_lock);

	if (dmat->flags & BUS_DMA_KEEP_PG_OFFSET) {
		/* Page offset needs to be preserved. */
		bpage->vaddr |= vaddr & PAGE_MASK;
		bpage->busaddr |= vaddr & PAGE_MASK;
	}
	bpage->datavaddr = vaddr;
	bpage->datacount = size;
	STAILQ_INSERT_TAIL(&(map->bpages), bpage, links);
	return (bpage->busaddr);
}

static void
free_bounce_page(bus_dma_tag_t dmat, struct bounce_page *bpage)
{
	struct bus_dmamap *map;

	bpage->datavaddr = 0;
	bpage->datacount = 0;
	if (dmat->flags & BUS_DMA_KEEP_PG_OFFSET) {
		/*
		 * Reset the bounce page to start at offset 0.  Other uses
		 * of this bounce page may need to store a full page of
		 * data and/or assume it starts on a page boundary.
		 */
		bpage->vaddr &= ~PAGE_MASK;
		bpage->busaddr &= ~PAGE_MASK;
	}

	mtx_lock(&bounce_lock);
	STAILQ_INSERT_HEAD(&bounce_page_list, bpage, links);
	free_bpages++;
	active_bpages--;
	if ((map = STAILQ_FIRST(&bounce_map_waitinglist)) != NULL) {
		if (reserve_bounce_pages(map->dmat, map, 1) == 0) {
			STAILQ_REMOVE_HEAD(&bounce_map_waitinglist, links);
			STAILQ_INSERT_TAIL(&bounce_map_callbacklist,
					   map, links);
			busdma_swi_pending = 1;
			total_deferred++;
			swi_sched(vm_ih, 0);
		}
	}
	mtx_unlock(&bounce_lock);
}

void
busdma_swi(void)
{
	bus_dma_tag_t dmat;
	struct bus_dmamap *map;

	mtx_lock(&bounce_lock);
	while ((map = STAILQ_FIRST(&bounce_map_callbacklist)) != NULL) {
		STAILQ_REMOVE_HEAD(&bounce_map_callbacklist, links);
		mtx_unlock(&bounce_lock);
		dmat = map->dmat;
		(dmat->lockfunc)(dmat->lockfuncarg, BUS_DMA_LOCK);
		bus_dmamap_load(map->dmat, map, map->buf, map->buflen,
				map->callback, map->callback_arg, /*flags*/0);
		(dmat->lockfunc)(dmat->lockfuncarg, BUS_DMA_UNLOCK);
		mtx_lock(&bounce_lock);
	}
	mtx_unlock(&bounce_lock);
}