summaryrefslogtreecommitdiff
path: root/drivers/gpu/drm/ttm/ttm_page_alloc_dma.c
blob: 4f9e548b2eec67e5a701f7017bb7a4ff95fb2f99 (plain)
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
1006
1007
1008
1009
1010
1011
1012
1013
1014
1015
1016
1017
1018
1019
1020
1021
1022
1023
1024
1025
1026
1027
1028
1029
1030
1031
1032
1033
1034
1035
1036
1037
1038
1039
1040
1041
1042
1043
1044
1045
1046
1047
1048
1049
1050
1051
1052
1053
1054
1055
1056
1057
1058
1059
1060
1061
1062
1063
1064
1065
1066
1067
1068
1069
1070
1071
1072
1073
1074
1075
1076
1077
1078
1079
1080
1081
1082
1083
1084
1085
1086
1087
1088
1089
1090
1091
1092
1093
1094
1095
1096
1097
1098
1099
1100
1101
1102
1103
1104
1105
1106
1107
1108
1109
1110
1111
1112
1113
1114
1115
1116
1117
1118
1119
1120
1121
1122
1123
1124
1125
1126
1127
1128
1129
1130
1131
1132
1133
1134
/*
 * Copyright 2011 (c) Oracle Corp.

 * Permission is hereby granted, free of charge, to any person obtaining a
 * copy of this software and associated documentation files (the "Software"),
 * to deal in the Software without restriction, including without limitation
 * the rights to use, copy, modify, merge, publish, distribute, sub license,
 * and/or sell copies of the Software, and to permit persons to whom the
 * Software is furnished to do so, subject to the following conditions:
 *
 * The above copyright notice and this permission notice (including the
 * next paragraph) shall be included in all copies or substantial portions
 * of the Software.
 *
 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
 * FITNESS FOR A PARTICULAR PURPOSE AND NON-INFRINGEMENT. IN NO EVENT SHALL
 * THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
 * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
 * FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER
 * DEALINGS IN THE SOFTWARE.
 *
 * Author: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
 */

/*
 * A simple DMA pool losely based on dmapool.c. It has certain advantages
 * over the DMA pools:
 * - Pool collects resently freed pages for reuse (and hooks up to
 *   the shrinker).
 * - Tracks currently in use pages
 * - Tracks whether the page is UC, WB or cached (and reverts to WB
 *   when freed).
 */

#define pr_fmt(fmt) "[TTM] " fmt

#include <linux/dma-mapping.h>
#include <linux/list.h>
#include <linux/seq_file.h> /* for seq_printf */
#include <linux/slab.h>
#include <linux/spinlock.h>
#include <linux/highmem.h>
#include <linux/mm_types.h>
#include <linux/module.h>
#include <linux/mm.h>
#include <linux/atomic.h>
#include <linux/device.h>
#include <linux/kthread.h>
#include "ttm/ttm_bo_driver.h"
#include "ttm/ttm_page_alloc.h"
#ifdef TTM_HAS_AGP
#include <asm/agp.h>
#endif

#define NUM_PAGES_TO_ALLOC		(PAGE_SIZE/sizeof(struct page *))
#define SMALL_ALLOCATION		4
#define FREE_ALL_PAGES			(~0U)
/* times are in msecs */
#define IS_UNDEFINED			(0)
#define IS_WC				(1<<1)
#define IS_UC				(1<<2)
#define IS_CACHED			(1<<3)
#define IS_DMA32			(1<<4)

enum pool_type {
	POOL_IS_UNDEFINED,
	POOL_IS_WC = IS_WC,
	POOL_IS_UC = IS_UC,
	POOL_IS_CACHED = IS_CACHED,
	POOL_IS_WC_DMA32 = IS_WC | IS_DMA32,
	POOL_IS_UC_DMA32 = IS_UC | IS_DMA32,
	POOL_IS_CACHED_DMA32 = IS_CACHED | IS_DMA32,
};
/*
 * The pool structure. There are usually six pools:
 *  - generic (not restricted to DMA32):
 *      - write combined, uncached, cached.
 *  - dma32 (up to 2^32 - so up 4GB):
 *      - write combined, uncached, cached.
 * for each 'struct device'. The 'cached' is for pages that are actively used.
 * The other ones can be shrunk by the shrinker API if neccessary.
 * @pools: The 'struct device->dma_pools' link.
 * @type: Type of the pool
 * @lock: Protects the inuse_list and free_list from concurrnet access. Must be
 * used with irqsave/irqrestore variants because pool allocator maybe called
 * from delayed work.
 * @inuse_list: Pool of pages that are in use. The order is very important and
 *   it is in the order that the TTM pages that are put back are in.
 * @free_list: Pool of pages that are free to be used. No order requirements.
 * @dev: The device that is associated with these pools.
 * @size: Size used during DMA allocation.
 * @npages_free: Count of available pages for re-use.
 * @npages_in_use: Count of pages that are in use.
 * @nfrees: Stats when pool is shrinking.
 * @nrefills: Stats when the pool is grown.
 * @gfp_flags: Flags to pass for alloc_page.
 * @name: Name of the pool.
 * @dev_name: Name derieved from dev - similar to how dev_info works.
 *   Used during shutdown as the dev_info during release is unavailable.
 */
struct dma_pool {
	struct list_head pools; /* The 'struct device->dma_pools link */
	enum pool_type type;
	spinlock_t lock;
	struct list_head inuse_list;
	struct list_head free_list;
	struct device *dev;
	unsigned size;
	unsigned npages_free;
	unsigned npages_in_use;
	unsigned long nfrees; /* Stats when shrunk. */
	unsigned long nrefills; /* Stats when grown. */
	gfp_t gfp_flags;
	char name[13]; /* "cached dma32" */
	char dev_name[64]; /* Constructed from dev */
};

/*
 * The accounting page keeping track of the allocated page along with
 * the DMA address.
 * @page_list: The link to the 'page_list' in 'struct dma_pool'.
 * @vaddr: The virtual address of the page
 * @dma: The bus address of the page. If the page is not allocated
 *   via the DMA API, it will be -1.
 */
struct dma_page {
	struct list_head page_list;
	void *vaddr;
	struct page *p;
	dma_addr_t dma;
};

/*
 * Limits for the pool. They are handled without locks because only place where
 * they may change is in sysfs store. They won't have immediate effect anyway
 * so forcing serialization to access them is pointless.
 */

struct ttm_pool_opts {
	unsigned	alloc_size;
	unsigned	max_size;
	unsigned	small;
};

/*
 * Contains the list of all of the 'struct device' and their corresponding
 * DMA pools. Guarded by _mutex->lock.
 * @pools: The link to 'struct ttm_pool_manager->pools'
 * @dev: The 'struct device' associated with the 'pool'
 * @pool: The 'struct dma_pool' associated with the 'dev'
 */
struct device_pools {
	struct list_head pools;
	struct device *dev;
	struct dma_pool *pool;
};

/*
 * struct ttm_pool_manager - Holds memory pools for fast allocation
 *
 * @lock: Lock used when adding/removing from pools
 * @pools: List of 'struct device' and 'struct dma_pool' tuples.
 * @options: Limits for the pool.
 * @npools: Total amount of pools in existence.
 * @shrinker: The structure used by [un|]register_shrinker
 */
struct ttm_pool_manager {
	struct mutex		lock;
	struct list_head	pools;
	struct ttm_pool_opts	options;
	unsigned		npools;
	struct shrinker		mm_shrink;
	struct kobject		kobj;
};

static struct ttm_pool_manager *_manager;

static struct attribute ttm_page_pool_max = {
	.name = "pool_max_size",
	.mode = S_IRUGO | S_IWUSR
};
static struct attribute ttm_page_pool_small = {
	.name = "pool_small_allocation",
	.mode = S_IRUGO | S_IWUSR
};
static struct attribute ttm_page_pool_alloc_size = {
	.name = "pool_allocation_size",
	.mode = S_IRUGO | S_IWUSR
};

static struct attribute *ttm_pool_attrs[] = {
	&ttm_page_pool_max,
	&ttm_page_pool_small,
	&ttm_page_pool_alloc_size,
	NULL
};

static void ttm_pool_kobj_release(struct kobject *kobj)
{
	struct ttm_pool_manager *m =
		container_of(kobj, struct ttm_pool_manager, kobj);
	kfree(m);
}

static ssize_t ttm_pool_store(struct kobject *kobj, struct attribute *attr,
			      const char *buffer, size_t size)
{
	struct ttm_pool_manager *m =
		container_of(kobj, struct ttm_pool_manager, kobj);
	int chars;
	unsigned val;
	chars = sscanf(buffer, "%u", &val);
	if (chars == 0)
		return size;

	/* Convert kb to number of pages */
	val = val / (PAGE_SIZE >> 10);

	if (attr == &ttm_page_pool_max)
		m->options.max_size = val;
	else if (attr == &ttm_page_pool_small)
		m->options.small = val;
	else if (attr == &ttm_page_pool_alloc_size) {
		if (val > NUM_PAGES_TO_ALLOC*8) {
			pr_err("Setting allocation size to %lu is not allowed. Recommended size is %lu\n",
			       NUM_PAGES_TO_ALLOC*(PAGE_SIZE >> 7),
			       NUM_PAGES_TO_ALLOC*(PAGE_SIZE >> 10));
			return size;
		} else if (val > NUM_PAGES_TO_ALLOC) {
			pr_warn("Setting allocation size to larger than %lu is not recommended\n",
				NUM_PAGES_TO_ALLOC*(PAGE_SIZE >> 10));
		}
		m->options.alloc_size = val;
	}

	return size;
}

static ssize_t ttm_pool_show(struct kobject *kobj, struct attribute *attr,
			     char *buffer)
{
	struct ttm_pool_manager *m =
		container_of(kobj, struct ttm_pool_manager, kobj);
	unsigned val = 0;

	if (attr == &ttm_page_pool_max)
		val = m->options.max_size;
	else if (attr == &ttm_page_pool_small)
		val = m->options.small;
	else if (attr == &ttm_page_pool_alloc_size)
		val = m->options.alloc_size;

	val = val * (PAGE_SIZE >> 10);

	return snprintf(buffer, PAGE_SIZE, "%u\n", val);
}

static const struct sysfs_ops ttm_pool_sysfs_ops = {
	.show = &ttm_pool_show,
	.store = &ttm_pool_store,
};

static struct kobj_type ttm_pool_kobj_type = {
	.release = &ttm_pool_kobj_release,
	.sysfs_ops = &ttm_pool_sysfs_ops,
	.default_attrs = ttm_pool_attrs,
};

#ifndef CONFIG_X86
static int set_pages_array_wb(struct page **pages, int addrinarray)
{
#ifdef TTM_HAS_AGP
	int i;

	for (i = 0; i < addrinarray; i++)
		unmap_page_from_agp(pages[i]);
#endif
	return 0;
}

static int set_pages_array_wc(struct page **pages, int addrinarray)
{
#ifdef TTM_HAS_AGP
	int i;

	for (i = 0; i < addrinarray; i++)
		map_page_into_agp(pages[i]);
#endif
	return 0;
}

static int set_pages_array_uc(struct page **pages, int addrinarray)
{
#ifdef TTM_HAS_AGP
	int i;

	for (i = 0; i < addrinarray; i++)
		map_page_into_agp(pages[i]);
#endif
	return 0;
}
#endif /* for !CONFIG_X86 */

static int ttm_set_pages_caching(struct dma_pool *pool,
				 struct page **pages, unsigned cpages)
{
	int r = 0;
	/* Set page caching */
	if (pool->type & IS_UC) {
		r = set_pages_array_uc(pages, cpages);
		if (r)
			pr_err("%s: Failed to set %d pages to uc!\n",
			       pool->dev_name, cpages);
	}
	if (pool->type & IS_WC) {
		r = set_pages_array_wc(pages, cpages);
		if (r)
			pr_err("%s: Failed to set %d pages to wc!\n",
			       pool->dev_name, cpages);
	}
	return r;
}

static void __ttm_dma_free_page(struct dma_pool *pool, struct dma_page *d_page)
{
	dma_addr_t dma = d_page->dma;
	dma_free_coherent(pool->dev, pool->size, d_page->vaddr, dma);

	kfree(d_page);
	d_page = NULL;
}
static struct dma_page *__ttm_dma_alloc_page(struct dma_pool *pool)
{
	struct dma_page *d_page;

	d_page = kmalloc(sizeof(struct dma_page), GFP_KERNEL);
	if (!d_page)
		return NULL;

	d_page->vaddr = dma_alloc_coherent(pool->dev, pool->size,
					   &d_page->dma,
					   pool->gfp_flags);
	if (d_page->vaddr)
		d_page->p = virt_to_page(d_page->vaddr);
	else {
		kfree(d_page);
		d_page = NULL;
	}
	return d_page;
}
static enum pool_type ttm_to_type(int flags, enum ttm_caching_state cstate)
{
	enum pool_type type = IS_UNDEFINED;

	if (flags & TTM_PAGE_FLAG_DMA32)
		type |= IS_DMA32;
	if (cstate == tt_cached)
		type |= IS_CACHED;
	else if (cstate == tt_uncached)
		type |= IS_UC;
	else
		type |= IS_WC;

	return type;
}

static void ttm_pool_update_free_locked(struct dma_pool *pool,
					unsigned freed_pages)
{
	pool->npages_free -= freed_pages;
	pool->nfrees += freed_pages;

}

/* set memory back to wb and free the pages. */
static void ttm_dma_pages_put(struct dma_pool *pool, struct list_head *d_pages,
			      struct page *pages[], unsigned npages)
{
	struct dma_page *d_page, *tmp;

	/* Don't set WB on WB page pool. */
	if (npages && !(pool->type & IS_CACHED) &&
	    set_pages_array_wb(pages, npages))
		pr_err("%s: Failed to set %d pages to wb!\n",
		       pool->dev_name, npages);

	list_for_each_entry_safe(d_page, tmp, d_pages, page_list) {
		list_del(&d_page->page_list);
		__ttm_dma_free_page(pool, d_page);
	}
}

static void ttm_dma_page_put(struct dma_pool *pool, struct dma_page *d_page)
{
	/* Don't set WB on WB page pool. */
	if (!(pool->type & IS_CACHED) && set_pages_array_wb(&d_page->p, 1))
		pr_err("%s: Failed to set %d pages to wb!\n",
		       pool->dev_name, 1);

	list_del(&d_page->page_list);
	__ttm_dma_free_page(pool, d_page);
}

/*
 * Free pages from pool.
 *
 * To prevent hogging the ttm_swap process we only free NUM_PAGES_TO_ALLOC
 * number of pages in one go.
 *
 * @pool: to free the pages from
 * @nr_free: If set to true will free all pages in pool
 **/
static unsigned ttm_dma_page_pool_free(struct dma_pool *pool, unsigned nr_free)
{
	unsigned long irq_flags;
	struct dma_page *dma_p, *tmp;
	struct page **pages_to_free;
	struct list_head d_pages;
	unsigned freed_pages = 0,
		 npages_to_free = nr_free;

	if (NUM_PAGES_TO_ALLOC < nr_free)
		npages_to_free = NUM_PAGES_TO_ALLOC;
#if 0
	if (nr_free > 1) {
		pr_debug("%s: (%s:%d) Attempting to free %d (%d) pages\n",
			 pool->dev_name, pool->name, current->pid,
			 npages_to_free, nr_free);
	}
#endif
	pages_to_free = kmalloc(npages_to_free * sizeof(struct page *),
			GFP_KERNEL);

	if (!pages_to_free) {
		pr_err("%s: Failed to allocate memory for pool free operation\n",
		       pool->dev_name);
		return 0;
	}
	INIT_LIST_HEAD(&d_pages);
restart:
	spin_lock_irqsave(&pool->lock, irq_flags);

	/* We picking the oldest ones off the list */
	list_for_each_entry_safe_reverse(dma_p, tmp, &pool->free_list,
					 page_list) {
		if (freed_pages >= npages_to_free)
			break;

		/* Move the dma_page from one list to another. */
		list_move(&dma_p->page_list, &d_pages);

		pages_to_free[freed_pages++] = dma_p->p;
		/* We can only remove NUM_PAGES_TO_ALLOC at a time. */
		if (freed_pages >= NUM_PAGES_TO_ALLOC) {

			ttm_pool_update_free_locked(pool, freed_pages);
			/**
			 * Because changing page caching is costly
			 * we unlock the pool to prevent stalling.
			 */
			spin_unlock_irqrestore(&pool->lock, irq_flags);

			ttm_dma_pages_put(pool, &d_pages, pages_to_free,
					  freed_pages);

			INIT_LIST_HEAD(&d_pages);

			if (likely(nr_free != FREE_ALL_PAGES))
				nr_free -= freed_pages;

			if (NUM_PAGES_TO_ALLOC >= nr_free)
				npages_to_free = nr_free;
			else
				npages_to_free = NUM_PAGES_TO_ALLOC;

			freed_pages = 0;

			/* free all so restart the processing */
			if (nr_free)
				goto restart;

			/* Not allowed to fall through or break because
			 * following context is inside spinlock while we are
			 * outside here.
			 */
			goto out;

		}
	}

	/* remove range of pages from the pool */
	if (freed_pages) {
		ttm_pool_update_free_locked(pool, freed_pages);
		nr_free -= freed_pages;
	}

	spin_unlock_irqrestore(&pool->lock, irq_flags);

	if (freed_pages)
		ttm_dma_pages_put(pool, &d_pages, pages_to_free, freed_pages);
out:
	kfree(pages_to_free);
	return nr_free;
}

static void ttm_dma_free_pool(struct device *dev, enum pool_type type)
{
	struct device_pools *p;
	struct dma_pool *pool;

	if (!dev)
		return;

	mutex_lock(&_manager->lock);
	list_for_each_entry_reverse(p, &_manager->pools, pools) {
		if (p->dev != dev)
			continue;
		pool = p->pool;
		if (pool->type != type)
			continue;

		list_del(&p->pools);
		kfree(p);
		_manager->npools--;
		break;
	}
	list_for_each_entry_reverse(pool, &dev->dma_pools, pools) {
		if (pool->type != type)
			continue;
		/* Takes a spinlock.. */
		ttm_dma_page_pool_free(pool, FREE_ALL_PAGES);
		WARN_ON(((pool->npages_in_use + pool->npages_free) != 0));
		/* This code path is called after _all_ references to the
		 * struct device has been dropped - so nobody should be
		 * touching it. In case somebody is trying to _add_ we are
		 * guarded by the mutex. */
		list_del(&pool->pools);
		kfree(pool);
		break;
	}
	mutex_unlock(&_manager->lock);
}

/*
 * On free-ing of the 'struct device' this deconstructor is run.
 * Albeit the pool might have already been freed earlier.
 */
static void ttm_dma_pool_release(struct device *dev, void *res)
{
	struct dma_pool *pool = *(struct dma_pool **)res;

	if (pool)
		ttm_dma_free_pool(dev, pool->type);
}

static int ttm_dma_pool_match(struct device *dev, void *res, void *match_data)
{
	return *(struct dma_pool **)res == match_data;
}

static struct dma_pool *ttm_dma_pool_init(struct device *dev, gfp_t flags,
					  enum pool_type type)
{
	char *n[] = {"wc", "uc", "cached", " dma32", "unknown",};
	enum pool_type t[] = {IS_WC, IS_UC, IS_CACHED, IS_DMA32, IS_UNDEFINED};
	struct device_pools *sec_pool = NULL;
	struct dma_pool *pool = NULL, **ptr;
	unsigned i;
	int ret = -ENODEV;
	char *p;

	if (!dev)
		return NULL;

	ptr = devres_alloc(ttm_dma_pool_release, sizeof(*ptr), GFP_KERNEL);
	if (!ptr)
		return NULL;

	ret = -ENOMEM;

	pool = kmalloc_node(sizeof(struct dma_pool), GFP_KERNEL,
			    dev_to_node(dev));
	if (!pool)
		goto err_mem;

	sec_pool = kmalloc_node(sizeof(struct device_pools), GFP_KERNEL,
				dev_to_node(dev));
	if (!sec_pool)
		goto err_mem;

	INIT_LIST_HEAD(&sec_pool->pools);
	sec_pool->dev = dev;
	sec_pool->pool =  pool;

	INIT_LIST_HEAD(&pool->free_list);
	INIT_LIST_HEAD(&pool->inuse_list);
	INIT_LIST_HEAD(&pool->pools);
	spin_lock_init(&pool->lock);
	pool->dev = dev;
	pool->npages_free = pool->npages_in_use = 0;
	pool->nfrees = 0;
	pool->gfp_flags = flags;
	pool->size = PAGE_SIZE;
	pool->type = type;
	pool->nrefills = 0;
	p = pool->name;
	for (i = 0; i < 5; i++) {
		if (type & t[i]) {
			p += snprintf(p, sizeof(pool->name) - (p - pool->name),
				      "%s", n[i]);
		}
	}
	*p = 0;
	/* We copy the name for pr_ calls b/c when dma_pool_destroy is called
	 * - the kobj->name has already been deallocated.*/
	snprintf(pool->dev_name, sizeof(pool->dev_name), "%s %s",
		 dev_driver_string(dev), dev_name(dev));
	mutex_lock(&_manager->lock);
	/* You can get the dma_pool from either the global: */
	list_add(&sec_pool->pools, &_manager->pools);
	_manager->npools++;
	/* or from 'struct device': */
	list_add(&pool->pools, &dev->dma_pools);
	mutex_unlock(&_manager->lock);

	*ptr = pool;
	devres_add(dev, ptr);

	return pool;
err_mem:
	devres_free(ptr);
	kfree(sec_pool);
	kfree(pool);
	return ERR_PTR(ret);
}

static struct dma_pool *ttm_dma_find_pool(struct device *dev,
					  enum pool_type type)
{
	struct dma_pool *pool, *tmp, *found = NULL;

	if (type == IS_UNDEFINED)
		return found;

	/* NB: We iterate on the 'struct dev' which has no spinlock, but
	 * it does have a kref which we have taken. The kref is taken during
	 * graphic driver loading - in the drm_pci_init it calls either
	 * pci_dev_get or pci_register_driver which both end up taking a kref
	 * on 'struct device'.
	 *
	 * On teardown, the graphic drivers end up quiescing the TTM (put_pages)
	 * and calls the dev_res deconstructors: ttm_dma_pool_release. The nice
	 * thing is at that point of time there are no pages associated with the
	 * driver so this function will not be called.
	 */
	list_for_each_entry_safe(pool, tmp, &dev->dma_pools, pools) {
		if (pool->type != type)
			continue;
		found = pool;
		break;
	}
	return found;
}

/*
 * Free pages the pages that failed to change the caching state. If there
 * are pages that have changed their caching state already put them to the
 * pool.
 */
static void ttm_dma_handle_caching_state_failure(struct dma_pool *pool,
						 struct list_head *d_pages,
						 struct page **failed_pages,
						 unsigned cpages)
{
	struct dma_page *d_page, *tmp;
	struct page *p;
	unsigned i = 0;

	p = failed_pages[0];
	if (!p)
		return;
	/* Find the failed page. */
	list_for_each_entry_safe(d_page, tmp, d_pages, page_list) {
		if (d_page->p != p)
			continue;
		/* .. and then progress over the full list. */
		list_del(&d_page->page_list);
		__ttm_dma_free_page(pool, d_page);
		if (++i < cpages)
			p = failed_pages[i];
		else
			break;
	}

}

/*
 * Allocate 'count' pages, and put 'need' number of them on the
 * 'pages' and as well on the 'dma_address' starting at 'dma_offset' offset.
 * The full list of pages should also be on 'd_pages'.
 * We return zero for success, and negative numbers as errors.
 */
static int ttm_dma_pool_alloc_new_pages(struct dma_pool *pool,
					struct list_head *d_pages,
					unsigned count)
{
	struct page **caching_array;
	struct dma_page *dma_p;
	struct page *p;
	int r = 0;
	unsigned i, cpages;
	unsigned max_cpages = min(count,
			(unsigned)(PAGE_SIZE/sizeof(struct page *)));

	/* allocate array for page caching change */
	caching_array = kmalloc(max_cpages*sizeof(struct page *), GFP_KERNEL);

	if (!caching_array) {
		pr_err("%s: Unable to allocate table for new pages\n",
		       pool->dev_name);
		return -ENOMEM;
	}

	if (count > 1) {
		pr_debug("%s: (%s:%d) Getting %d pages\n",
			 pool->dev_name, pool->name, current->pid, count);
	}

	for (i = 0, cpages = 0; i < count; ++i) {
		dma_p = __ttm_dma_alloc_page(pool);
		if (!dma_p) {
			pr_err("%s: Unable to get page %u\n",
			       pool->dev_name, i);

			/* store already allocated pages in the pool after
			 * setting the caching state */
			if (cpages) {
				r = ttm_set_pages_caching(pool, caching_array,
							  cpages);
				if (r)
					ttm_dma_handle_caching_state_failure(
						pool, d_pages, caching_array,
						cpages);
			}
			r = -ENOMEM;
			goto out;
		}
		p = dma_p->p;
#ifdef CONFIG_HIGHMEM
		/* gfp flags of highmem page should never be dma32 so we
		 * we should be fine in such case
		 */
		if (!PageHighMem(p))
#endif
		{
			caching_array[cpages++] = p;
			if (cpages == max_cpages) {
				/* Note: Cannot hold the spinlock */
				r = ttm_set_pages_caching(pool, caching_array,
						 cpages);
				if (r) {
					ttm_dma_handle_caching_state_failure(
						pool, d_pages, caching_array,
						cpages);
					goto out;
				}
				cpages = 0;
			}
		}
		list_add(&dma_p->page_list, d_pages);
	}

	if (cpages) {
		r = ttm_set_pages_caching(pool, caching_array, cpages);
		if (r)
			ttm_dma_handle_caching_state_failure(pool, d_pages,
					caching_array, cpages);
	}
out:
	kfree(caching_array);
	return r;
}

/*
 * @return count of pages still required to fulfill the request.
 */
static int ttm_dma_page_pool_fill_locked(struct dma_pool *pool,
					 unsigned long *irq_flags)
{
	unsigned count = _manager->options.small;
	int r = pool->npages_free;

	if (count > pool->npages_free) {
		struct list_head d_pages;

		INIT_LIST_HEAD(&d_pages);

		spin_unlock_irqrestore(&pool->lock, *irq_flags);

		/* Returns how many more are neccessary to fulfill the
		 * request. */
		r = ttm_dma_pool_alloc_new_pages(pool, &d_pages, count);

		spin_lock_irqsave(&pool->lock, *irq_flags);
		if (!r) {
			/* Add the fresh to the end.. */
			list_splice(&d_pages, &pool->free_list);
			++pool->nrefills;
			pool->npages_free += count;
			r = count;
		} else {
			struct dma_page *d_page;
			unsigned cpages = 0;

			pr_err("%s: Failed to fill %s pool (r:%d)!\n",
			       pool->dev_name, pool->name, r);

			list_for_each_entry(d_page, &d_pages, page_list) {
				cpages++;
			}
			list_splice_tail(&d_pages, &pool->free_list);
			pool->npages_free += cpages;
			r = cpages;
		}
	}
	return r;
}

/*
 * @return count of pages still required to fulfill the request.
 * The populate list is actually a stack (not that is matters as TTM
 * allocates one page at a time.
 */
static int ttm_dma_pool_get_pages(struct dma_pool *pool,
				  struct ttm_dma_tt *ttm_dma,
				  unsigned index)
{
	struct dma_page *d_page;
	struct ttm_tt *ttm = &ttm_dma->ttm;
	unsigned long irq_flags;
	int count, r = -ENOMEM;

	spin_lock_irqsave(&pool->lock, irq_flags);
	count = ttm_dma_page_pool_fill_locked(pool, &irq_flags);
	if (count) {
		d_page = list_first_entry(&pool->free_list, struct dma_page, page_list);
		ttm->pages[index] = d_page->p;
		ttm_dma->dma_address[index] = d_page->dma;
		list_move_tail(&d_page->page_list, &ttm_dma->pages_list);
		r = 0;
		pool->npages_in_use += 1;
		pool->npages_free -= 1;
	}
	spin_unlock_irqrestore(&pool->lock, irq_flags);
	return r;
}

/*
 * On success pages list will hold count number of correctly
 * cached pages. On failure will hold the negative return value (-ENOMEM, etc).
 */
int ttm_dma_populate(struct ttm_dma_tt *ttm_dma, struct device *dev)
{
	struct ttm_tt *ttm = &ttm_dma->ttm;
	struct ttm_mem_global *mem_glob = ttm->glob->mem_glob;
	struct dma_pool *pool;
	enum pool_type type;
	unsigned i;
	gfp_t gfp_flags;
	int ret;

	if (ttm->state != tt_unpopulated)
		return 0;

	type = ttm_to_type(ttm->page_flags, ttm->caching_state);
	if (ttm->page_flags & TTM_PAGE_FLAG_DMA32)
		gfp_flags = GFP_USER | GFP_DMA32;
	else
		gfp_flags = GFP_HIGHUSER;
	if (ttm->page_flags & TTM_PAGE_FLAG_ZERO_ALLOC)
		gfp_flags |= __GFP_ZERO;

	pool = ttm_dma_find_pool(dev, type);
	if (!pool) {
		pool = ttm_dma_pool_init(dev, gfp_flags, type);
		if (IS_ERR_OR_NULL(pool)) {
			return -ENOMEM;
		}
	}

	INIT_LIST_HEAD(&ttm_dma->pages_list);
	for (i = 0; i < ttm->num_pages; ++i) {
		ret = ttm_dma_pool_get_pages(pool, ttm_dma, i);
		if (ret != 0) {
			ttm_dma_unpopulate(ttm_dma, dev);
			return -ENOMEM;
		}

		ret = ttm_mem_global_alloc_page(mem_glob, ttm->pages[i],
						false, false);
		if (unlikely(ret != 0)) {
			ttm_dma_unpopulate(ttm_dma, dev);
			return -ENOMEM;
		}
	}

	if (unlikely(ttm->page_flags & TTM_PAGE_FLAG_SWAPPED)) {
		ret = ttm_tt_swapin(ttm);
		if (unlikely(ret != 0)) {
			ttm_dma_unpopulate(ttm_dma, dev);
			return ret;
		}
	}

	ttm->state = tt_unbound;
	return 0;
}
EXPORT_SYMBOL_GPL(ttm_dma_populate);

/* Get good estimation how many pages are free in pools */
static int ttm_dma_pool_get_num_unused_pages(void)
{
	struct device_pools *p;
	unsigned total = 0;

	mutex_lock(&_manager->lock);
	list_for_each_entry(p, &_manager->pools, pools)
		total += p->pool->npages_free;
	mutex_unlock(&_manager->lock);
	return total;
}

/* Put all pages in pages list to correct pool to wait for reuse */
void ttm_dma_unpopulate(struct ttm_dma_tt *ttm_dma, struct device *dev)
{
	struct ttm_tt *ttm = &ttm_dma->ttm;
	struct dma_pool *pool;
	struct dma_page *d_page, *next;
	enum pool_type type;
	bool is_cached = false;
	unsigned count = 0, i, npages = 0;
	unsigned long irq_flags;

	type = ttm_to_type(ttm->page_flags, ttm->caching_state);
	pool = ttm_dma_find_pool(dev, type);
	if (!pool)
		return;

	is_cached = (ttm_dma_find_pool(pool->dev,
		     ttm_to_type(ttm->page_flags, tt_cached)) == pool);

	/* make sure pages array match list and count number of pages */
	list_for_each_entry(d_page, &ttm_dma->pages_list, page_list) {
		ttm->pages[count] = d_page->p;
		count++;
	}

	spin_lock_irqsave(&pool->lock, irq_flags);
	pool->npages_in_use -= count;
	if (is_cached) {
		pool->nfrees += count;
	} else {
		pool->npages_free += count;
		list_splice(&ttm_dma->pages_list, &pool->free_list);
		npages = count;
		if (pool->npages_free > _manager->options.max_size) {
			npages = pool->npages_free - _manager->options.max_size;
			/* free at least NUM_PAGES_TO_ALLOC number of pages
			 * to reduce calls to set_memory_wb */
			if (npages < NUM_PAGES_TO_ALLOC)
				npages = NUM_PAGES_TO_ALLOC;
		}
	}
	spin_unlock_irqrestore(&pool->lock, irq_flags);

	if (is_cached) {
		list_for_each_entry_safe(d_page, next, &ttm_dma->pages_list, page_list) {
			ttm_mem_global_free_page(ttm->glob->mem_glob,
						 d_page->p);
			ttm_dma_page_put(pool, d_page);
		}
	} else {
		for (i = 0; i < count; i++) {
			ttm_mem_global_free_page(ttm->glob->mem_glob,
						 ttm->pages[i]);
		}
	}

	INIT_LIST_HEAD(&ttm_dma->pages_list);
	for (i = 0; i < ttm->num_pages; i++) {
		ttm->pages[i] = NULL;
		ttm_dma->dma_address[i] = 0;
	}

	/* shrink pool if necessary (only on !is_cached pools)*/
	if (npages)
		ttm_dma_page_pool_free(pool, npages);
	ttm->state = tt_unpopulated;
}
EXPORT_SYMBOL_GPL(ttm_dma_unpopulate);

/**
 * Callback for mm to request pool to reduce number of page held.
 */
static int ttm_dma_pool_mm_shrink(struct shrinker *shrink,
				  struct shrink_control *sc)
{
	static atomic_t start_pool = ATOMIC_INIT(0);
	unsigned idx = 0;
	unsigned pool_offset = atomic_add_return(1, &start_pool);
	unsigned shrink_pages = sc->nr_to_scan;
	struct device_pools *p;

	if (list_empty(&_manager->pools))
		return 0;

	mutex_lock(&_manager->lock);
	pool_offset = pool_offset % _manager->npools;
	list_for_each_entry(p, &_manager->pools, pools) {
		unsigned nr_free;

		if (!p->dev)
			continue;
		if (shrink_pages == 0)
			break;
		/* Do it in round-robin fashion. */
		if (++idx < pool_offset)
			continue;
		nr_free = shrink_pages;
		shrink_pages = ttm_dma_page_pool_free(p->pool, nr_free);
		pr_debug("%s: (%s:%d) Asked to shrink %d, have %d more to go\n",
			 p->pool->dev_name, p->pool->name, current->pid,
			 nr_free, shrink_pages);
	}
	mutex_unlock(&_manager->lock);
	/* return estimated number of unused pages in pool */
	return ttm_dma_pool_get_num_unused_pages();
}

static void ttm_dma_pool_mm_shrink_init(struct ttm_pool_manager *manager)
{
	manager->mm_shrink.shrink = &ttm_dma_pool_mm_shrink;
	manager->mm_shrink.seeks = 1;
	register_shrinker(&manager->mm_shrink);
}

static void ttm_dma_pool_mm_shrink_fini(struct ttm_pool_manager *manager)
{
	unregister_shrinker(&manager->mm_shrink);
}

int ttm_dma_page_alloc_init(struct ttm_mem_global *glob, unsigned max_pages)
{
	int ret = -ENOMEM;

	WARN_ON(_manager);

	pr_info("Initializing DMA pool allocator\n");

	_manager = kzalloc(sizeof(*_manager), GFP_KERNEL);
	if (!_manager)
		goto err_manager;

	mutex_init(&_manager->lock);
	INIT_LIST_HEAD(&_manager->pools);

	_manager->options.max_size = max_pages;
	_manager->options.small = SMALL_ALLOCATION;
	_manager->options.alloc_size = NUM_PAGES_TO_ALLOC;

	/* This takes care of auto-freeing the _manager */
	ret = kobject_init_and_add(&_manager->kobj, &ttm_pool_kobj_type,
				   &glob->kobj, "dma_pool");
	if (unlikely(ret != 0)) {
		kobject_put(&_manager->kobj);
		goto err;
	}
	ttm_dma_pool_mm_shrink_init(_manager);
	return 0;
err_manager:
	kfree(_manager);
	_manager = NULL;
err:
	return ret;
}

void ttm_dma_page_alloc_fini(void)
{
	struct device_pools *p, *t;

	pr_info("Finalizing DMA pool allocator\n");
	ttm_dma_pool_mm_shrink_fini(_manager);

	list_for_each_entry_safe_reverse(p, t, &_manager->pools, pools) {
		dev_dbg(p->dev, "(%s:%d) Freeing.\n", p->pool->name,
			current->pid);
		WARN_ON(devres_destroy(p->dev, ttm_dma_pool_release,
			ttm_dma_pool_match, p->pool));
		ttm_dma_free_pool(p->dev, p->pool->type);
	}
	kobject_put(&_manager->kobj);
	_manager = NULL;
}

int ttm_dma_page_alloc_debugfs(struct seq_file *m, void *data)
{
	struct device_pools *p;
	struct dma_pool *pool = NULL;
	char *h[] = {"pool", "refills", "pages freed", "inuse", "available",
		     "name", "virt", "busaddr"};

	if (!_manager) {
		seq_printf(m, "No pool allocator running.\n");
		return 0;
	}
	seq_printf(m, "%13s %12s %13s %8s %8s %8s\n",
		   h[0], h[1], h[2], h[3], h[4], h[5]);
	mutex_lock(&_manager->lock);
	list_for_each_entry(p, &_manager->pools, pools) {
		struct device *dev = p->dev;
		if (!dev)
			continue;
		pool = p->pool;
		seq_printf(m, "%13s %12ld %13ld %8d %8d %8s\n",
				pool->name, pool->nrefills,
				pool->nfrees, pool->npages_in_use,
				pool->npages_free,
				pool->dev_name);
	}
	mutex_unlock(&_manager->lock);
	return 0;
}
EXPORT_SYMBOL_GPL(ttm_dma_page_alloc_debugfs);