summaryrefslogtreecommitdiffstats
path: root/drivers/mtd/nand/atmel/pmecc.c
blob: 146af82183145d9d5164665aeaccdf789c4cca98 (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
/*
 * Copyright 2017 ATMEL
 * Copyright 2017 Free Electrons
 *
 * Author: Boris Brezillon <boris.brezillon@free-electrons.com>
 *
 * Derived from the atmel_nand.c driver which contained the following
 * copyrights:
 *
 *   Copyright 2003 Rick Bronson
 *
 *   Derived from drivers/mtd/nand/autcpu12.c
 *	Copyright 2001 Thomas Gleixner (gleixner@autronix.de)
 *
 *   Derived from drivers/mtd/spia.c
 *	Copyright 2000 Steven J. Hill (sjhill@cotw.com)
 *
 *   Add Hardware ECC support for AT91SAM9260 / AT91SAM9263
 *	Richard Genoud (richard.genoud@gmail.com), Adeneo Copyright 2007
 *
 *   Derived from Das U-Boot source code
 *	(u-boot-1.1.5/board/atmel/at91sam9263ek/nand.c)
 *      Copyright 2006 ATMEL Rousset, Lacressonniere Nicolas
 *
 *   Add Programmable Multibit ECC support for various AT91 SoC
 *	Copyright 2012 ATMEL, Hong Xu
 *
 *   Add Nand Flash Controller support for SAMA5 SoC
 *	Copyright 2013 ATMEL, Josh Wu (josh.wu@atmel.com)
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License version 2 as
 * published by the Free Software Foundation.
 *
 * The PMECC is an hardware assisted BCH engine, which means part of the
 * ECC algorithm is left to the software. The hardware/software repartition
 * is explained in the "PMECC Controller Functional Description" chapter in
 * Atmel datasheets, and some of the functions in this file are directly
 * implementing the algorithms described in the "Software Implementation"
 * sub-section.
 *
 * TODO: it seems that the software BCH implementation in lib/bch.c is already
 * providing some of the logic we are implementing here. It would be smart
 * to expose the needed lib/bch.c helpers/functions and re-use them here.
 */

#include <linux/genalloc.h>
#include <linux/iopoll.h>
#include <linux/module.h>
#include <linux/mtd/rawnand.h>
#include <linux/of_irq.h>
#include <linux/of_platform.h>
#include <linux/platform_device.h>
#include <linux/slab.h>

#include "pmecc.h"

/* Galois field dimension */
#define PMECC_GF_DIMENSION_13			13
#define PMECC_GF_DIMENSION_14			14

/* Primitive Polynomial used by PMECC */
#define PMECC_GF_13_PRIMITIVE_POLY		0x201b
#define PMECC_GF_14_PRIMITIVE_POLY		0x4443

#define PMECC_LOOKUP_TABLE_SIZE_512		0x2000
#define PMECC_LOOKUP_TABLE_SIZE_1024		0x4000

/* Time out value for reading PMECC status register */
#define PMECC_MAX_TIMEOUT_MS			100

/* PMECC Register Definitions */
#define ATMEL_PMECC_CFG				0x0
#define PMECC_CFG_BCH_STRENGTH(x)		(x)
#define PMECC_CFG_BCH_STRENGTH_MASK		GENMASK(2, 0)
#define PMECC_CFG_SECTOR512			(0 << 4)
#define PMECC_CFG_SECTOR1024			(1 << 4)
#define PMECC_CFG_NSECTORS(x)			((fls(x) - 1) << 8)
#define PMECC_CFG_READ_OP			(0 << 12)
#define PMECC_CFG_WRITE_OP			(1 << 12)
#define PMECC_CFG_SPARE_ENABLE			BIT(16)
#define PMECC_CFG_AUTO_ENABLE			BIT(20)

#define ATMEL_PMECC_SAREA			0x4
#define ATMEL_PMECC_SADDR			0x8
#define ATMEL_PMECC_EADDR			0xc

#define ATMEL_PMECC_CLK				0x10
#define PMECC_CLK_133MHZ			(2 << 0)

#define ATMEL_PMECC_CTRL			0x14
#define PMECC_CTRL_RST				BIT(0)
#define PMECC_CTRL_DATA				BIT(1)
#define PMECC_CTRL_USER				BIT(2)
#define PMECC_CTRL_ENABLE			BIT(4)
#define PMECC_CTRL_DISABLE			BIT(5)

#define ATMEL_PMECC_SR				0x18
#define PMECC_SR_BUSY				BIT(0)
#define PMECC_SR_ENABLE				BIT(4)

#define ATMEL_PMECC_IER				0x1c
#define ATMEL_PMECC_IDR				0x20
#define ATMEL_PMECC_IMR				0x24
#define ATMEL_PMECC_ISR				0x28
#define PMECC_ERROR_INT				BIT(0)

#define ATMEL_PMECC_ECC(sector, n)		\
	((((sector) + 1) * 0x40) + (n))

#define ATMEL_PMECC_REM(sector, n)		\
	((((sector) + 1) * 0x40) + ((n) * 4) + 0x200)

/* PMERRLOC Register Definitions */
#define ATMEL_PMERRLOC_ELCFG			0x0
#define PMERRLOC_ELCFG_SECTOR_512		(0 << 0)
#define PMERRLOC_ELCFG_SECTOR_1024		(1 << 0)
#define PMERRLOC_ELCFG_NUM_ERRORS(n)		((n) << 16)

#define ATMEL_PMERRLOC_ELPRIM			0x4
#define ATMEL_PMERRLOC_ELEN			0x8
#define ATMEL_PMERRLOC_ELDIS			0xc
#define PMERRLOC_DISABLE			BIT(0)

#define ATMEL_PMERRLOC_ELSR			0x10
#define PMERRLOC_ELSR_BUSY			BIT(0)

#define ATMEL_PMERRLOC_ELIER			0x14
#define ATMEL_PMERRLOC_ELIDR			0x18
#define ATMEL_PMERRLOC_ELIMR			0x1c
#define ATMEL_PMERRLOC_ELISR			0x20
#define PMERRLOC_ERR_NUM_MASK			GENMASK(12, 8)
#define PMERRLOC_CALC_DONE			BIT(0)

#define ATMEL_PMERRLOC_SIGMA(x)			(((x) * 0x4) + 0x28)

#define ATMEL_PMERRLOC_EL(offs, x)		(((x) * 0x4) + (offs))

struct atmel_pmecc_gf_tables {
	u16 *alpha_to;
	u16 *index_of;
};

struct atmel_pmecc_caps {
	const int *strengths;
	int nstrengths;
	int el_offset;
	bool correct_erased_chunks;
};

struct atmel_pmecc {
	struct device *dev;
	const struct atmel_pmecc_caps *caps;

	struct {
		void __iomem *base;
		void __iomem *errloc;
	} regs;

	struct mutex lock;
};

struct atmel_pmecc_user_conf_cache {
	u32 cfg;
	u32 sarea;
	u32 saddr;
	u32 eaddr;
};

struct atmel_pmecc_user {
	struct atmel_pmecc_user_conf_cache cache;
	struct atmel_pmecc *pmecc;
	const struct atmel_pmecc_gf_tables *gf_tables;
	int eccbytes;
	s16 *partial_syn;
	s16 *si;
	s16 *lmu;
	s16 *smu;
	s32 *mu;
	s32 *dmu;
	s32 *delta;
	u32 isr;
};

static DEFINE_MUTEX(pmecc_gf_tables_lock);
static const struct atmel_pmecc_gf_tables *pmecc_gf_tables_512;
static const struct atmel_pmecc_gf_tables *pmecc_gf_tables_1024;

static inline int deg(unsigned int poly)
{
	/* polynomial degree is the most-significant bit index */
	return fls(poly) - 1;
}

static int atmel_pmecc_build_gf_tables(int mm, unsigned int poly,
				       struct atmel_pmecc_gf_tables *gf_tables)
{
	unsigned int i, x = 1;
	const unsigned int k = BIT(deg(poly));
	unsigned int nn = BIT(mm) - 1;

	/* primitive polynomial must be of degree m */
	if (k != (1u << mm))
		return -EINVAL;

	for (i = 0; i < nn; i++) {
		gf_tables->alpha_to[i] = x;
		gf_tables->index_of[x] = i;
		if (i && (x == 1))
			/* polynomial is not primitive (a^i=1 with 0<i<2^m-1) */
			return -EINVAL;
		x <<= 1;
		if (x & k)
			x ^= poly;
	}
	gf_tables->alpha_to[nn] = 1;
	gf_tables->index_of[0] = 0;

	return 0;
}

static const struct atmel_pmecc_gf_tables *
atmel_pmecc_create_gf_tables(const struct atmel_pmecc_user_req *req)
{
	struct atmel_pmecc_gf_tables *gf_tables;
	unsigned int poly, degree, table_size;
	int ret;

	if (req->ecc.sectorsize == 512) {
		degree = PMECC_GF_DIMENSION_13;
		poly = PMECC_GF_13_PRIMITIVE_POLY;
		table_size = PMECC_LOOKUP_TABLE_SIZE_512;
	} else {
		degree = PMECC_GF_DIMENSION_14;
		poly = PMECC_GF_14_PRIMITIVE_POLY;
		table_size = PMECC_LOOKUP_TABLE_SIZE_1024;
	}

	gf_tables = kzalloc(sizeof(*gf_tables) +
			    (2 * table_size * sizeof(u16)),
			    GFP_KERNEL);
	if (!gf_tables)
		return ERR_PTR(-ENOMEM);

	gf_tables->alpha_to = (void *)(gf_tables + 1);
	gf_tables->index_of = gf_tables->alpha_to + table_size;

	ret = atmel_pmecc_build_gf_tables(degree, poly, gf_tables);
	if (ret) {
		kfree(gf_tables);
		return ERR_PTR(ret);
	}

	return gf_tables;
}

static const struct atmel_pmecc_gf_tables *
atmel_pmecc_get_gf_tables(const struct atmel_pmecc_user_req *req)
{
	const struct atmel_pmecc_gf_tables **gf_tables, *ret;

	mutex_lock(&pmecc_gf_tables_lock);
	if (req->ecc.sectorsize == 512)
		gf_tables = &pmecc_gf_tables_512;
	else
		gf_tables = &pmecc_gf_tables_1024;

	ret = *gf_tables;

	if (!ret) {
		ret = atmel_pmecc_create_gf_tables(req);
		if (!IS_ERR(ret))
			*gf_tables = ret;
	}
	mutex_unlock(&pmecc_gf_tables_lock);

	return ret;
}

static int atmel_pmecc_prepare_user_req(struct atmel_pmecc *pmecc,
					struct atmel_pmecc_user_req *req)
{
	int i, max_eccbytes, eccbytes = 0, eccstrength = 0;

	if (req->pagesize <= 0 || req->oobsize <= 0 || req->ecc.bytes <= 0)
		return -EINVAL;

	if (req->ecc.ooboffset >= 0 &&
	    req->ecc.ooboffset + req->ecc.bytes > req->oobsize)
		return -EINVAL;

	if (req->ecc.sectorsize == ATMEL_PMECC_SECTOR_SIZE_AUTO) {
		if (req->ecc.strength != ATMEL_PMECC_MAXIMIZE_ECC_STRENGTH)
			return -EINVAL;

		if (req->pagesize > 512)
			req->ecc.sectorsize = 1024;
		else
			req->ecc.sectorsize = 512;
	}

	if (req->ecc.sectorsize != 512 && req->ecc.sectorsize != 1024)
		return -EINVAL;

	if (req->pagesize % req->ecc.sectorsize)
		return -EINVAL;

	req->ecc.nsectors = req->pagesize / req->ecc.sectorsize;

	max_eccbytes = req->ecc.bytes;

	for (i = 0; i < pmecc->caps->nstrengths; i++) {
		int nbytes, strength = pmecc->caps->strengths[i];

		if (req->ecc.strength != ATMEL_PMECC_MAXIMIZE_ECC_STRENGTH &&
		    strength < req->ecc.strength)
			continue;

		nbytes = DIV_ROUND_UP(strength * fls(8 * req->ecc.sectorsize),
				      8);
		nbytes *= req->ecc.nsectors;

		if (nbytes > max_eccbytes)
			break;

		eccstrength = strength;
		eccbytes = nbytes;

		if (req->ecc.strength != ATMEL_PMECC_MAXIMIZE_ECC_STRENGTH)
			break;
	}

	if (!eccstrength)
		return -EINVAL;

	req->ecc.bytes = eccbytes;
	req->ecc.strength = eccstrength;

	if (req->ecc.ooboffset < 0)
		req->ecc.ooboffset = req->oobsize - eccbytes;

	return 0;
}

struct atmel_pmecc_user *
atmel_pmecc_create_user(struct atmel_pmecc *pmecc,
			struct atmel_pmecc_user_req *req)
{
	struct atmel_pmecc_user *user;
	const struct atmel_pmecc_gf_tables *gf_tables;
	int strength, size, ret;

	ret = atmel_pmecc_prepare_user_req(pmecc, req);
	if (ret)
		return ERR_PTR(ret);

	size = sizeof(*user);
	size = ALIGN(size, sizeof(u16));
	/* Reserve space for partial_syn, si and smu */
	size += ((2 * req->ecc.strength) + 1) * sizeof(u16) *
		(2 + req->ecc.strength + 2);
	/* Reserve space for lmu. */
	size += (req->ecc.strength + 1) * sizeof(u16);
	/* Reserve space for mu, dmu and delta. */
	size = ALIGN(size, sizeof(s32));
	size += (req->ecc.strength + 1) * sizeof(s32);

	user = kzalloc(size, GFP_KERNEL);
	if (!user)
		return ERR_PTR(-ENOMEM);

	user->pmecc = pmecc;

	user->partial_syn = (s16 *)PTR_ALIGN(user + 1, sizeof(u16));
	user->si = user->partial_syn + ((2 * req->ecc.strength) + 1);
	user->lmu = user->si + ((2 * req->ecc.strength) + 1);
	user->smu = user->lmu + (req->ecc.strength + 1);
	user->mu = (s32 *)PTR_ALIGN(user->smu +
				    (((2 * req->ecc.strength) + 1) *
				     (req->ecc.strength + 2)),
				    sizeof(s32));
	user->dmu = user->mu + req->ecc.strength + 1;
	user->delta = user->dmu + req->ecc.strength + 1;

	gf_tables = atmel_pmecc_get_gf_tables(req);
	if (IS_ERR(gf_tables)) {
		kfree(user);
		return ERR_CAST(gf_tables);
	}

	user->gf_tables = gf_tables;

	user->eccbytes = req->ecc.bytes / req->ecc.nsectors;

	for (strength = 0; strength < pmecc->caps->nstrengths; strength++) {
		if (pmecc->caps->strengths[strength] == req->ecc.strength)
			break;
	}

	user->cache.cfg = PMECC_CFG_BCH_STRENGTH(strength) |
			  PMECC_CFG_NSECTORS(req->ecc.nsectors);

	if (req->ecc.sectorsize == 1024)
		user->cache.cfg |= PMECC_CFG_SECTOR1024;

	user->cache.sarea = req->oobsize - 1;
	user->cache.saddr = req->ecc.ooboffset;
	user->cache.eaddr = req->ecc.ooboffset + req->ecc.bytes - 1;

	return user;
}
EXPORT_SYMBOL_GPL(atmel_pmecc_create_user);

void atmel_pmecc_destroy_user(struct atmel_pmecc_user *user)
{
	kfree(user);
}
EXPORT_SYMBOL_GPL(atmel_pmecc_destroy_user);

static int get_strength(struct atmel_pmecc_user *user)
{
	const int *strengths = user->pmecc->caps->strengths;

	return strengths[user->cache.cfg & PMECC_CFG_BCH_STRENGTH_MASK];
}

static int get_sectorsize(struct atmel_pmecc_user *user)
{
	return user->cache.cfg & PMECC_LOOKUP_TABLE_SIZE_1024 ? 1024 : 512;
}

static void atmel_pmecc_gen_syndrome(struct atmel_pmecc_user *user, int sector)
{
	int strength = get_strength(user);
	u32 value;
	int i;

	/* Fill odd syndromes */
	for (i = 0; i < strength; i++) {
		value = readl_relaxed(user->pmecc->regs.base +
				      ATMEL_PMECC_REM(sector, i / 2));
		if (i & 1)
			value >>= 16;

		user->partial_syn[(2 * i) + 1] = value;
	}
}

static void atmel_pmecc_substitute(struct atmel_pmecc_user *user)
{
	int degree = get_sectorsize(user) == 512 ? 13 : 14;
	int cw_len = BIT(degree) - 1;
	int strength = get_strength(user);
	s16 *alpha_to = user->gf_tables->alpha_to;
	s16 *index_of = user->gf_tables->index_of;
	s16 *partial_syn = user->partial_syn;
	s16 *si;
	int i, j;

	/*
	 * si[] is a table that holds the current syndrome value,
	 * an element of that table belongs to the field
	 */
	si = user->si;

	memset(&si[1], 0, sizeof(s16) * ((2 * strength) - 1));

	/* Computation 2t syndromes based on S(x) */
	/* Odd syndromes */
	for (i = 1; i < 2 * strength; i += 2) {
		for (j = 0; j < degree; j++) {
			if (partial_syn[i] & BIT(j))
				si[i] = alpha_to[i * j] ^ si[i];
		}
	}
	/* Even syndrome = (Odd syndrome) ** 2 */
	for (i = 2, j = 1; j <= strength; i = ++j << 1) {
		if (si[j] == 0) {
			si[i] = 0;
		} else {
			s16 tmp;

			tmp = index_of[si[j]];
			tmp = (tmp * 2) % cw_len;
			si[i] = alpha_to[tmp];
		}
	}
}

static void atmel_pmecc_get_sigma(struct atmel_pmecc_user *user)
{
	s16 *lmu = user->lmu;
	s16 *si = user->si;
	s32 *mu = user->mu;
	s32 *dmu = user->dmu;
	s32 *delta = user->delta;
	int degree = get_sectorsize(user) == 512 ? 13 : 14;
	int cw_len = BIT(degree) - 1;
	int strength = get_strength(user);
	int num = 2 * strength + 1;
	s16 *index_of = user->gf_tables->index_of;
	s16 *alpha_to = user->gf_tables->alpha_to;
	int i, j, k;
	u32 dmu_0_count, tmp;
	s16 *smu = user->smu;

	/* index of largest delta */
	int ro;
	int largest;
	int diff;

	dmu_0_count = 0;

	/* First Row */

	/* Mu */
	mu[0] = -1;

	memset(smu, 0, sizeof(s16) * num);
	smu[0] = 1;

	/* discrepancy set to 1 */
	dmu[0] = 1;
	/* polynom order set to 0 */
	lmu[0] = 0;
	delta[0] = (mu[0] * 2 - lmu[0]) >> 1;

	/* Second Row */

	/* Mu */
	mu[1] = 0;
	/* Sigma(x) set to 1 */
	memset(&smu[num], 0, sizeof(s16) * num);
	smu[num] = 1;

	/* discrepancy set to S1 */
	dmu[1] = si[1];

	/* polynom order set to 0 */
	lmu[1] = 0;

	delta[1] = (mu[1] * 2 - lmu[1]) >> 1;

	/* Init the Sigma(x) last row */
	memset(&smu[(strength + 1) * num], 0, sizeof(s16) * num);

	for (i = 1; i <= strength; i++) {
		mu[i + 1] = i << 1;
		/* Begin Computing Sigma (Mu+1) and L(mu) */
		/* check if discrepancy is set to 0 */
		if (dmu[i] == 0) {
			dmu_0_count++;

			tmp = ((strength - (lmu[i] >> 1) - 1) / 2);
			if ((strength - (lmu[i] >> 1) - 1) & 0x1)
				tmp += 2;
			else
				tmp += 1;

			if (dmu_0_count == tmp) {
				for (j = 0; j <= (lmu[i] >> 1) + 1; j++)
					smu[(strength + 1) * num + j] =
							smu[i * num + j];

				lmu[strength + 1] = lmu[i];
				return;
			}

			/* copy polynom */
			for (j = 0; j <= lmu[i] >> 1; j++)
				smu[(i + 1) * num + j] = smu[i * num + j];

			/* copy previous polynom order to the next */
			lmu[i + 1] = lmu[i];
		} else {
			ro = 0;
			largest = -1;
			/* find largest delta with dmu != 0 */
			for (j = 0; j < i; j++) {
				if ((dmu[j]) && (delta[j] > largest)) {
					largest = delta[j];
					ro = j;
				}
			}

			/* compute difference */
			diff = (mu[i] - mu[ro]);

			/* Compute degree of the new smu polynomial */
			if ((lmu[i] >> 1) > ((lmu[ro] >> 1) + diff))
				lmu[i + 1] = lmu[i];
			else
				lmu[i + 1] = ((lmu[ro] >> 1) + diff) * 2;

			/* Init smu[i+1] with 0 */
			for (k = 0; k < num; k++)
				smu[(i + 1) * num + k] = 0;

			/* Compute smu[i+1] */
			for (k = 0; k <= lmu[ro] >> 1; k++) {
				s16 a, b, c;

				if (!(smu[ro * num + k] && dmu[i]))
					continue;

				a = index_of[dmu[i]];
				b = index_of[dmu[ro]];
				c = index_of[smu[ro * num + k]];
				tmp = a + (cw_len - b) + c;
				a = alpha_to[tmp % cw_len];
				smu[(i + 1) * num + (k + diff)] = a;
			}

			for (k = 0; k <= lmu[i] >> 1; k++)
				smu[(i + 1) * num + k] ^= smu[i * num + k];
		}

		/* End Computing Sigma (Mu+1) and L(mu) */
		/* In either case compute delta */
		delta[i + 1] = (mu[i + 1] * 2 - lmu[i + 1]) >> 1;

		/* Do not compute discrepancy for the last iteration */
		if (i >= strength)
			continue;

		for (k = 0; k <= (lmu[i + 1] >> 1); k++) {
			tmp = 2 * (i - 1);
			if (k == 0) {
				dmu[i + 1] = si[tmp + 3];
			} else if (smu[(i + 1) * num + k] && si[tmp + 3 - k]) {
				s16 a, b, c;

				a = index_of[smu[(i + 1) * num + k]];
				b = si[2 * (i - 1) + 3 - k];
				c = index_of[b];
				tmp = a + c;
				tmp %= cw_len;
				dmu[i + 1] = alpha_to[tmp] ^ dmu[i + 1];
			}
		}
	}
}

static int atmel_pmecc_err_location(struct atmel_pmecc_user *user)
{
	int sector_size = get_sectorsize(user);
	int degree = sector_size == 512 ? 13 : 14;
	struct atmel_pmecc *pmecc = user->pmecc;
	int strength = get_strength(user);
	int ret, roots_nbr, i, err_nbr = 0;
	int num = (2 * strength) + 1;
	s16 *smu = user->smu;
	u32 val;

	writel(PMERRLOC_DISABLE, pmecc->regs.errloc + ATMEL_PMERRLOC_ELDIS);

	for (i = 0; i <= user->lmu[strength + 1] >> 1; i++) {
		writel_relaxed(smu[(strength + 1) * num + i],
			       pmecc->regs.errloc + ATMEL_PMERRLOC_SIGMA(i));
		err_nbr++;
	}

	val = (err_nbr - 1) << 16;
	if (sector_size == 1024)
		val |= 1;

	writel(val, pmecc->regs.errloc + ATMEL_PMERRLOC_ELCFG);
	writel((sector_size * 8) + (degree * strength),
	       pmecc->regs.errloc + ATMEL_PMERRLOC_ELEN);

	ret = readl_relaxed_poll_timeout(pmecc->regs.errloc +
					 ATMEL_PMERRLOC_ELISR,
					 val, val & PMERRLOC_CALC_DONE, 0,
					 PMECC_MAX_TIMEOUT_MS * 1000);
	if (ret) {
		dev_err(pmecc->dev,
			"PMECC: Timeout to calculate error location.\n");
		return ret;
	}

	roots_nbr = (val & PMERRLOC_ERR_NUM_MASK) >> 8;
	/* Number of roots == degree of smu hence <= cap */
	if (roots_nbr == user->lmu[strength + 1] >> 1)
		return err_nbr - 1;

	/*
	 * Number of roots does not match the degree of smu
	 * unable to correct error.
	 */
	return -EBADMSG;
}

int atmel_pmecc_correct_sector(struct atmel_pmecc_user *user, int sector,
			       void *data, void *ecc)
{
	struct atmel_pmecc *pmecc = user->pmecc;
	int sectorsize = get_sectorsize(user);
	int eccbytes = user->eccbytes;
	int i, nerrors;

	if (!(user->isr & BIT(sector)))
		return 0;

	atmel_pmecc_gen_syndrome(user, sector);
	atmel_pmecc_substitute(user);
	atmel_pmecc_get_sigma(user);

	nerrors = atmel_pmecc_err_location(user);
	if (nerrors < 0)
		return nerrors;

	for (i = 0; i < nerrors; i++) {
		const char *area;
		int byte, bit;
		u32 errpos;
		u8 *ptr;

		errpos = readl_relaxed(pmecc->regs.errloc +
				ATMEL_PMERRLOC_EL(pmecc->caps->el_offset, i));
		errpos--;

		byte = errpos / 8;
		bit = errpos % 8;

		if (byte < sectorsize) {
			ptr = data + byte;
			area = "data";
		} else if (byte < sectorsize + eccbytes) {
			ptr = ecc + byte - sectorsize;
			area = "ECC";
		} else {
			dev_dbg(pmecc->dev,
				"Invalid errpos value (%d, max is %d)\n",
				errpos, (sectorsize + eccbytes) * 8);
			return -EINVAL;
		}

		dev_dbg(pmecc->dev,
			"Bit flip in %s area, byte %d: 0x%02x -> 0x%02x\n",
			area, byte, *ptr, (unsigned int)(*ptr ^ BIT(bit)));

		*ptr ^= BIT(bit);
	}

	return nerrors;
}
EXPORT_SYMBOL_GPL(atmel_pmecc_correct_sector);

bool atmel_pmecc_correct_erased_chunks(struct atmel_pmecc_user *user)
{
	return user->pmecc->caps->correct_erased_chunks;
}
EXPORT_SYMBOL_GPL(atmel_pmecc_correct_erased_chunks);

void atmel_pmecc_get_generated_eccbytes(struct atmel_pmecc_user *user,
					int sector, void *ecc)
{
	struct atmel_pmecc *pmecc = user->pmecc;
	u8 *ptr = ecc;
	int i;

	for (i = 0; i < user->eccbytes; i++)
		ptr[i] = readb_relaxed(pmecc->regs.base +
				       ATMEL_PMECC_ECC(sector, i));
}
EXPORT_SYMBOL_GPL(atmel_pmecc_get_generated_eccbytes);

int atmel_pmecc_enable(struct atmel_pmecc_user *user, int op)
{
	struct atmel_pmecc *pmecc = user->pmecc;
	u32 cfg;

	if (op != NAND_ECC_READ && op != NAND_ECC_WRITE) {
		dev_err(pmecc->dev, "Bad ECC operation!");
		return -EINVAL;
	}

	mutex_lock(&user->pmecc->lock);

	cfg = user->cache.cfg;
	if (op == NAND_ECC_WRITE)
		cfg |= PMECC_CFG_WRITE_OP;
	else
		cfg |= PMECC_CFG_AUTO_ENABLE;

	writel(cfg, pmecc->regs.base + ATMEL_PMECC_CFG);
	writel(user->cache.sarea, pmecc->regs.base + ATMEL_PMECC_SAREA);
	writel(user->cache.saddr, pmecc->regs.base + ATMEL_PMECC_SADDR);
	writel(user->cache.eaddr, pmecc->regs.base + ATMEL_PMECC_EADDR);

	writel(PMECC_CTRL_ENABLE, pmecc->regs.base + ATMEL_PMECC_CTRL);
	writel(PMECC_CTRL_DATA, pmecc->regs.base + ATMEL_PMECC_CTRL);

	return 0;
}
EXPORT_SYMBOL_GPL(atmel_pmecc_enable);

void atmel_pmecc_disable(struct atmel_pmecc_user *user)
{
	struct atmel_pmecc *pmecc = user->pmecc;

	writel(PMECC_CTRL_RST, pmecc->regs.base + ATMEL_PMECC_CTRL);
	writel(PMECC_CTRL_DISABLE, pmecc->regs.base + ATMEL_PMECC_CTRL);
	mutex_unlock(&user->pmecc->lock);
}
EXPORT_SYMBOL_GPL(atmel_pmecc_disable);

int atmel_pmecc_wait_rdy(struct atmel_pmecc_user *user)
{
	struct atmel_pmecc *pmecc = user->pmecc;
	u32 status;
	int ret;

	ret = readl_relaxed_poll_timeout(pmecc->regs.base +
					 ATMEL_PMECC_SR,
					 status, !(status & PMECC_SR_BUSY), 0,
					 PMECC_MAX_TIMEOUT_MS * 1000);
	if (ret) {
		dev_err(pmecc->dev,
			"Timeout while waiting for PMECC ready.\n");
		return ret;
	}

	user->isr = readl_relaxed(pmecc->regs.base + ATMEL_PMECC_ISR);

	return 0;
}
EXPORT_SYMBOL_GPL(atmel_pmecc_wait_rdy);

static struct atmel_pmecc *atmel_pmecc_create(struct platform_device *pdev,
					const struct atmel_pmecc_caps *caps,
					int pmecc_res_idx, int errloc_res_idx)
{
	struct device *dev = &pdev->dev;
	struct atmel_pmecc *pmecc;
	struct resource *res;

	pmecc = devm_kzalloc(dev, sizeof(*pmecc), GFP_KERNEL);
	if (!pmecc)
		return ERR_PTR(-ENOMEM);

	pmecc->caps = caps;
	pmecc->dev = dev;
	mutex_init(&pmecc->lock);

	res = platform_get_resource(pdev, IORESOURCE_MEM, pmecc_res_idx);
	pmecc->regs.base = devm_ioremap_resource(dev, res);
	if (IS_ERR(pmecc->regs.base))
		return ERR_CAST(pmecc->regs.base);

	res = platform_get_resource(pdev, IORESOURCE_MEM, errloc_res_idx);
	pmecc->regs.errloc = devm_ioremap_resource(dev, res);
	if (IS_ERR(pmecc->regs.errloc))
		return ERR_CAST(pmecc->regs.errloc);

	/* Disable all interrupts before registering the PMECC handler. */
	writel(0xffffffff, pmecc->regs.base + ATMEL_PMECC_IDR);

	/* Reset the ECC engine */
	writel(PMECC_CTRL_RST, pmecc->regs.base + ATMEL_PMECC_CTRL);
	writel(PMECC_CTRL_DISABLE, pmecc->regs.base + ATMEL_PMECC_CTRL);

	return pmecc;
}

static void devm_atmel_pmecc_put(struct device *dev, void *res)
{
	struct atmel_pmecc **pmecc = res;

	put_device((*pmecc)->dev);
}

static struct atmel_pmecc *atmel_pmecc_get_by_node(struct device *userdev,
						   struct device_node *np)
{
	struct platform_device *pdev;
	struct atmel_pmecc *pmecc, **ptr;

	pdev = of_find_device_by_node(np);
	if (!pdev || !platform_get_drvdata(pdev))
		return ERR_PTR(-EPROBE_DEFER);

	ptr = devres_alloc(devm_atmel_pmecc_put, sizeof(*ptr), GFP_KERNEL);
	if (!ptr)
		return ERR_PTR(-ENOMEM);

	get_device(&pdev->dev);
	pmecc = platform_get_drvdata(pdev);

	*ptr = pmecc;

	devres_add(userdev, ptr);

	return pmecc;
}

static const int atmel_pmecc_strengths[] = { 2, 4, 8, 12, 24, 32 };

static struct atmel_pmecc_caps at91sam9g45_caps = {
	.strengths = atmel_pmecc_strengths,
	.nstrengths = 5,
	.el_offset = 0x8c,
};

static struct atmel_pmecc_caps sama5d4_caps = {
	.strengths = atmel_pmecc_strengths,
	.nstrengths = 5,
	.el_offset = 0x8c,
	.correct_erased_chunks = true,
};

static struct atmel_pmecc_caps sama5d2_caps = {
	.strengths = atmel_pmecc_strengths,
	.nstrengths = 6,
	.el_offset = 0xac,
	.correct_erased_chunks = true,
};

static const struct of_device_id atmel_pmecc_legacy_match[] = {
	{ .compatible = "atmel,sama5d4-nand", &sama5d4_caps },
	{ .compatible = "atmel,sama5d2-nand", &sama5d2_caps },
	{ /* sentinel */ }
};

struct atmel_pmecc *devm_atmel_pmecc_get(struct device *userdev)
{
	struct atmel_pmecc *pmecc;
	struct device_node *np;

	if (!userdev)
		return ERR_PTR(-EINVAL);

	if (!userdev->of_node)
		return NULL;

	np = of_parse_phandle(userdev->of_node, "ecc-engine", 0);
	if (np) {
		pmecc = atmel_pmecc_get_by_node(userdev, np);
		of_node_put(np);
	} else {
		/*
		 * Support old DT bindings: in this case the PMECC iomem
		 * resources are directly defined in the user pdev at position
		 * 1 and 2. Extract all relevant information from there.
		 */
		struct platform_device *pdev = to_platform_device(userdev);
		const struct atmel_pmecc_caps *caps;
		const struct of_device_id *match;

		/* No PMECC engine available. */
		if (!of_property_read_bool(userdev->of_node,
					   "atmel,has-pmecc"))
			return NULL;

		caps = &at91sam9g45_caps;

		/* Find the caps associated to the NAND dev node. */
		match = of_match_node(atmel_pmecc_legacy_match,
				      userdev->of_node);
		if (match && match->data)
			caps = match->data;

		pmecc = atmel_pmecc_create(pdev, caps, 1, 2);
	}

	return pmecc;
}
EXPORT_SYMBOL(devm_atmel_pmecc_get);

static const struct of_device_id atmel_pmecc_match[] = {
	{ .compatible = "atmel,at91sam9g45-pmecc", &at91sam9g45_caps },
	{ .compatible = "atmel,sama5d4-pmecc", &sama5d4_caps },
	{ .compatible = "atmel,sama5d2-pmecc", &sama5d2_caps },
	{ /* sentinel */ }
};
MODULE_DEVICE_TABLE(of, atmel_pmecc_match);

static int atmel_pmecc_probe(struct platform_device *pdev)
{
	struct device *dev = &pdev->dev;
	const struct atmel_pmecc_caps *caps;
	struct atmel_pmecc *pmecc;

	caps = of_device_get_match_data(&pdev->dev);
	if (!caps) {
		dev_err(dev, "Invalid caps\n");
		return -EINVAL;
	}

	pmecc = atmel_pmecc_create(pdev, caps, 0, 1);
	if (IS_ERR(pmecc))
		return PTR_ERR(pmecc);

	platform_set_drvdata(pdev, pmecc);

	return 0;
}

static struct platform_driver atmel_pmecc_driver = {
	.driver = {
		.name = "atmel-pmecc",
		.of_match_table = of_match_ptr(atmel_pmecc_match),
	},
	.probe = atmel_pmecc_probe,
};
module_platform_driver(atmel_pmecc_driver);

MODULE_LICENSE("GPL");
MODULE_AUTHOR("Boris Brezillon <boris.brezillon@free-electrons.com>");
MODULE_DESCRIPTION("PMECC engine driver");
MODULE_ALIAS("platform:atmel_pmecc");