summaryrefslogtreecommitdiff
path: root/drivers/mtd/nand/omap_gpmc.c
blob: 4372988ed2ab6c4295ff56c21318a5ae63d08687 (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
/*
 * (C) Copyright 2004-2008 Texas Instruments, <www.ti.com>
 * Rohit Choraria <rohitkc@ti.com>
 *
 * SPDX-License-Identifier:	GPL-2.0+
 */

#include <common.h>
#include <asm/io.h>
#include <asm/errno.h>
#include <asm/arch/mem.h>
#include <linux/mtd/omap_gpmc.h>
#include <linux/mtd/nand_ecc.h>
#include <linux/bch.h>
#include <linux/compiler.h>
#include <nand.h>
#include <linux/mtd/omap_elm.h>

#define BADBLOCK_MARKER_LENGTH	2
#define SECTOR_BYTES		512
#define ECCCLEAR		(0x1 << 8)
#define ECCRESULTREG1		(0x1 << 0)
/* 4 bit padding to make byte aligned, 56 = 52 + 4 */
#define BCH4_BIT_PAD		4

#ifdef CONFIG_BCH
static u8  bch8_polynomial[] = {0xef, 0x51, 0x2e, 0x09, 0xed, 0x93, 0x9a, 0xc2,
				0x97, 0x79, 0xe5, 0x24, 0xb5};
#endif
static uint8_t cs_next;
static __maybe_unused struct nand_ecclayout omap_ecclayout;

#if defined(CONFIG_NAND_OMAP_GPMC_WSCFG)
static const int8_t wscfg[CONFIG_SYS_MAX_NAND_DEVICE] =
	{ CONFIG_NAND_OMAP_GPMC_WSCFG };
#else
/* wscfg is preset to zero since its a static variable */
static const int8_t wscfg[CONFIG_SYS_MAX_NAND_DEVICE];
#endif

/*
 * Driver configurations
 */
struct omap_nand_info {
	struct bch_control *control;
	enum omap_ecc ecc_scheme;
	uint8_t cs;
	uint8_t ws;		/* wait status pin (0,1) */
};

/* We are wasting a bit of memory but al least we are safe */
static struct omap_nand_info omap_nand_info[GPMC_MAX_CS];

/*
 * omap_nand_hwcontrol - Set the address pointers corretly for the
 *			following address/data/command operation
 */
static void omap_nand_hwcontrol(struct mtd_info *mtd, int32_t cmd,
				uint32_t ctrl)
{
	register struct nand_chip *this = mtd->priv;
	struct omap_nand_info *info = this->priv;
	int cs = info->cs;

	/*
	 * Point the IO_ADDR to DATA and ADDRESS registers instead
	 * of chip address
	 */
	switch (ctrl) {
	case NAND_CTRL_CHANGE | NAND_CTRL_CLE:
		this->IO_ADDR_W = (void __iomem *)&gpmc_cfg->cs[cs].nand_cmd;
		break;
	case NAND_CTRL_CHANGE | NAND_CTRL_ALE:
		this->IO_ADDR_W = (void __iomem *)&gpmc_cfg->cs[cs].nand_adr;
		break;
	case NAND_CTRL_CHANGE | NAND_NCE:
		this->IO_ADDR_W = (void __iomem *)&gpmc_cfg->cs[cs].nand_dat;
		break;
	}

	if (cmd != NAND_CMD_NONE)
		writeb(cmd, this->IO_ADDR_W);
}

/* Check wait pin as dev ready indicator */
static int omap_dev_ready(struct mtd_info *mtd)
{
	register struct nand_chip *this = mtd->priv;
	struct omap_nand_info *info = this->priv;
	return gpmc_cfg->status & (1 << (8 + info->ws));
}

/*
 * gen_true_ecc - This function will generate true ECC value, which
 * can be used when correcting data read from NAND flash memory core
 *
 * @ecc_buf:	buffer to store ecc code
 *
 * @return:	re-formatted ECC value
 */
static uint32_t gen_true_ecc(uint8_t *ecc_buf)
{
	return ecc_buf[0] | (ecc_buf[1] << 16) | ((ecc_buf[2] & 0xF0) << 20) |
		((ecc_buf[2] & 0x0F) << 8);
}

/*
 * omap_correct_data - Compares the ecc read from nand spare area with ECC
 * registers values and corrects one bit error if it has occured
 * Further details can be had from OMAP TRM and the following selected links:
 * http://en.wikipedia.org/wiki/Hamming_code
 * http://www.cs.utexas.edu/users/plaxton/c/337/05f/slides/ErrorCorrection-4.pdf
 *
 * @mtd:		 MTD device structure
 * @dat:		 page data
 * @read_ecc:		 ecc read from nand flash
 * @calc_ecc:		 ecc read from ECC registers
 *
 * @return 0 if data is OK or corrected, else returns -1
 */
static int __maybe_unused omap_correct_data(struct mtd_info *mtd, uint8_t *dat,
				uint8_t *read_ecc, uint8_t *calc_ecc)
{
	uint32_t orig_ecc, new_ecc, res, hm;
	uint16_t parity_bits, byte;
	uint8_t bit;

	/* Regenerate the orginal ECC */
	orig_ecc = gen_true_ecc(read_ecc);
	new_ecc = gen_true_ecc(calc_ecc);
	/* Get the XOR of real ecc */
	res = orig_ecc ^ new_ecc;
	if (res) {
		/* Get the hamming width */
		hm = hweight32(res);
		/* Single bit errors can be corrected! */
		if (hm == 12) {
			/* Correctable data! */
			parity_bits = res >> 16;
			bit = (parity_bits & 0x7);
			byte = (parity_bits >> 3) & 0x1FF;
			/* Flip the bit to correct */
			dat[byte] ^= (0x1 << bit);
		} else if (hm == 1) {
			printf("Error: Ecc is wrong\n");
			/* ECC itself is corrupted */
			return 2;
		} else {
			/*
			 * hm distance != parity pairs OR one, could mean 2 bit
			 * error OR potentially be on a blank page..
			 * orig_ecc: contains spare area data from nand flash.
			 * new_ecc: generated ecc while reading data area.
			 * Note: if the ecc = 0, all data bits from which it was
			 * generated are 0xFF.
			 * The 3 byte(24 bits) ecc is generated per 512byte
			 * chunk of a page. If orig_ecc(from spare area)
			 * is 0xFF && new_ecc(computed now from data area)=0x0,
			 * this means that data area is 0xFF and spare area is
			 * 0xFF. A sure sign of a erased page!
			 */
			if ((orig_ecc == 0x0FFF0FFF) && (new_ecc == 0x00000000))
				return 0;
			printf("Error: Bad compare! failed\n");
			/* detected 2 bit error */
			return -1;
		}
	}
	return 0;
}

/*
 * omap_enable_hwecc - configures GPMC as per ECC scheme before read/write
 * @mtd:	MTD device structure
 * @mode:	Read/Write mode
 */
__maybe_unused
static void omap_enable_hwecc(struct mtd_info *mtd, int32_t mode)
{
	struct nand_chip	*nand	= mtd->priv;
	struct omap_nand_info	*info	= nand->priv;
	unsigned int dev_width = (nand->options & NAND_BUSWIDTH_16) ? 1 : 0;
	unsigned int ecc_algo = 0;
	unsigned int bch_type = 0;
	unsigned int eccsize1 = 0x00, eccsize0 = 0x00, bch_wrapmode = 0x00;
	u32 ecc_size_config_val = 0;
	u32 ecc_config_val = 0;
	int cs = info->cs;

	/* configure GPMC for specific ecc-scheme */
	switch (info->ecc_scheme) {
	case OMAP_ECC_HAM1_CODE_SW:
		return;
	case OMAP_ECC_HAM1_CODE_HW:
		ecc_algo = 0x0;
		bch_type = 0x0;
		bch_wrapmode = 0x00;
		eccsize0 = 0xFF;
		eccsize1 = 0xFF;
		break;
	case OMAP_ECC_BCH8_CODE_HW_DETECTION_SW:
	case OMAP_ECC_BCH8_CODE_HW:
		ecc_algo = 0x1;
		bch_type = 0x1;
		if (mode == NAND_ECC_WRITE) {
			bch_wrapmode = 0x01;
			eccsize0 = 0;  /* extra bits in nibbles per sector */
			eccsize1 = 28; /* OOB bits in nibbles per sector */
		} else {
			bch_wrapmode = 0x01;
			eccsize0 = 26; /* ECC bits in nibbles per sector */
			eccsize1 = 2;  /* non-ECC bits in nibbles per sector */
		}
		break;
	case OMAP_ECC_BCH16_CODE_HW:
		ecc_algo = 0x1;
		bch_type = 0x2;
		if (mode == NAND_ECC_WRITE) {
			bch_wrapmode = 0x01;
			eccsize0 = 0;  /* extra bits in nibbles per sector */
			eccsize1 = 52; /* OOB bits in nibbles per sector */
		} else {
			bch_wrapmode = 0x01;
			eccsize0 = 52; /* ECC bits in nibbles per sector */
			eccsize1 = 0;  /* non-ECC bits in nibbles per sector */
		}
		break;
	default:
		return;
	}
	/* Clear ecc and enable bits */
	writel(ECCCLEAR | ECCRESULTREG1, &gpmc_cfg->ecc_control);
	/* Configure ecc size for BCH */
	ecc_size_config_val = (eccsize1 << 22) | (eccsize0 << 12);
	writel(ecc_size_config_val, &gpmc_cfg->ecc_size_config);

	/* Configure device details for BCH engine */
	ecc_config_val = ((ecc_algo << 16)	| /* HAM1 | BCHx */
			(bch_type << 12)	| /* BCH4/BCH8/BCH16 */
			(bch_wrapmode << 8)	| /* wrap mode */
			(dev_width << 7)	| /* bus width */
			(0x0 << 4)		| /* number of sectors */
			(cs <<  1)		| /* ECC CS */
			(0x1));			  /* enable ECC */
	writel(ecc_config_val, &gpmc_cfg->ecc_config);
}

/*
 *  omap_calculate_ecc - Read ECC result
 *  @mtd:	MTD structure
 *  @dat:	unused
 *  @ecc_code:	ecc_code buffer
 *  Using noninverted ECC can be considered ugly since writing a blank
 *  page ie. padding will clear the ECC bytes. This is no problem as
 *  long nobody is trying to write data on the seemingly unused page.
 *  Reading an erased page will produce an ECC mismatch between
 *  generated and read ECC bytes that has to be dealt with separately.
 *  E.g. if page is 0xFF (fresh erased), and if HW ECC engine within GPMC
 *  is used, the result of read will be 0x0 while the ECC offsets of the
 *  spare area will be 0xFF which will result in an ECC mismatch.
 */
static int omap_calculate_ecc(struct mtd_info *mtd, const uint8_t *dat,
				uint8_t *ecc_code)
{
	struct nand_chip *chip = mtd->priv;
	struct omap_nand_info *info = chip->priv;
	uint32_t *ptr, val = 0;
	int8_t i = 0, j;

	switch (info->ecc_scheme) {
	case OMAP_ECC_HAM1_CODE_HW:
		val = readl(&gpmc_cfg->ecc1_result);
		ecc_code[0] = val & 0xFF;
		ecc_code[1] = (val >> 16) & 0xFF;
		ecc_code[2] = ((val >> 8) & 0x0F) | ((val >> 20) & 0xF0);
		break;
#ifdef CONFIG_BCH
	case OMAP_ECC_BCH8_CODE_HW_DETECTION_SW:
#endif
	case OMAP_ECC_BCH8_CODE_HW:
		ptr = &gpmc_cfg->bch_result_0_3[0].bch_result_x[3];
		val = readl(ptr);
		ecc_code[i++] = (val >>  0) & 0xFF;
		ptr--;
		for (j = 0; j < 3; j++) {
			val = readl(ptr);
			ecc_code[i++] = (val >> 24) & 0xFF;
			ecc_code[i++] = (val >> 16) & 0xFF;
			ecc_code[i++] = (val >>  8) & 0xFF;
			ecc_code[i++] = (val >>  0) & 0xFF;
			ptr--;
		}
		break;
	case OMAP_ECC_BCH16_CODE_HW:
		val = readl(&gpmc_cfg->bch_result_4_6[0].bch_result_x[2]);
		ecc_code[i++] = (val >>  8) & 0xFF;
		ecc_code[i++] = (val >>  0) & 0xFF;
		val = readl(&gpmc_cfg->bch_result_4_6[0].bch_result_x[1]);
		ecc_code[i++] = (val >> 24) & 0xFF;
		ecc_code[i++] = (val >> 16) & 0xFF;
		ecc_code[i++] = (val >>  8) & 0xFF;
		ecc_code[i++] = (val >>  0) & 0xFF;
		val = readl(&gpmc_cfg->bch_result_4_6[0].bch_result_x[0]);
		ecc_code[i++] = (val >> 24) & 0xFF;
		ecc_code[i++] = (val >> 16) & 0xFF;
		ecc_code[i++] = (val >>  8) & 0xFF;
		ecc_code[i++] = (val >>  0) & 0xFF;
		for (j = 3; j >= 0; j--) {
			val = readl(&gpmc_cfg->bch_result_0_3[0].bch_result_x[j]
									);
			ecc_code[i++] = (val >> 24) & 0xFF;
			ecc_code[i++] = (val >> 16) & 0xFF;
			ecc_code[i++] = (val >>  8) & 0xFF;
			ecc_code[i++] = (val >>  0) & 0xFF;
		}
		break;
	default:
		return -EINVAL;
	}
	/* ECC scheme specific syndrome customizations */
	switch (info->ecc_scheme) {
	case OMAP_ECC_HAM1_CODE_HW:
		break;
#ifdef CONFIG_BCH
	case OMAP_ECC_BCH8_CODE_HW_DETECTION_SW:

		for (i = 0; i < chip->ecc.bytes; i++)
			*(ecc_code + i) = *(ecc_code + i) ^
						bch8_polynomial[i];
		break;
#endif
	case OMAP_ECC_BCH8_CODE_HW:
		ecc_code[chip->ecc.bytes - 1] = 0x00;
		break;
	case OMAP_ECC_BCH16_CODE_HW:
		break;
	default:
		return -EINVAL;
	}
	return 0;
}

#ifdef CONFIG_NAND_OMAP_GPMC_PREFETCH

#define PREFETCH_CONFIG1_CS_SHIFT	24
#define PREFETCH_FIFOTHRESHOLD_MAX	0x40
#define PREFETCH_FIFOTHRESHOLD(val)	((val) << 8)
#define PREFETCH_STATUS_COUNT(val)	(val & 0x00003fff)
#define PREFETCH_STATUS_FIFO_CNT(val)	((val >> 24) & 0x7F)
#define ENABLE_PREFETCH			(1 << 7)

/**
 * omap_prefetch_enable - configures and starts prefetch transfer
 * @fifo_th: fifo threshold to be used for read/ write
 * @count: number of bytes to be transferred
 * @is_write: prefetch read(0) or write post(1) mode
 * @cs: chip select to use
 */
static int omap_prefetch_enable(int fifo_th, unsigned int count, int is_write, int cs)
{
	uint32_t val;

	if (fifo_th > PREFETCH_FIFOTHRESHOLD_MAX)
		return -EINVAL;

	if (readl(&gpmc_cfg->prefetch_control))
		return -EBUSY;

	/* Set the amount of bytes to be prefetched */
	writel(count, &gpmc_cfg->prefetch_config2);

	val = (cs << PREFETCH_CONFIG1_CS_SHIFT) | (is_write & 1) |
		PREFETCH_FIFOTHRESHOLD(fifo_th) | ENABLE_PREFETCH;
	writel(val, &gpmc_cfg->prefetch_config1);

	/*  Start the prefetch engine */
	writel(1, &gpmc_cfg->prefetch_control);

	return 0;
}

/**
 * omap_prefetch_reset - disables and stops the prefetch engine
 */
static void omap_prefetch_reset(void)
{
	writel(0, &gpmc_cfg->prefetch_control);
	writel(0, &gpmc_cfg->prefetch_config1);
}

static int __read_prefetch_aligned(struct nand_chip *chip, uint32_t *buf, int len)
{
	int ret;
	uint32_t cnt;
	struct omap_nand_info *info = chip->priv;

	ret = omap_prefetch_enable(PREFETCH_FIFOTHRESHOLD_MAX, len, 0, info->cs);
	if (ret < 0)
		return ret;

	do {
		int i;

		cnt = readl(&gpmc_cfg->prefetch_status);
		cnt = PREFETCH_STATUS_FIFO_CNT(cnt);

		for (i = 0; i < cnt / 4; i++) {
			*buf++ = readl(CONFIG_SYS_NAND_BASE);
			len -= 4;
		}
	} while (len);

	omap_prefetch_reset();

	return 0;
}

static inline void omap_nand_read(struct mtd_info *mtd, uint8_t *buf, int len)
{
	struct nand_chip *chip = mtd->priv;

	if (chip->options & NAND_BUSWIDTH_16)
		nand_read_buf16(mtd, buf, len);
	else
		nand_read_buf(mtd, buf, len);
}

static void omap_nand_read_prefetch(struct mtd_info *mtd, uint8_t *buf, int len)
{
	int ret;
	uint32_t head, tail;
	struct nand_chip *chip = mtd->priv;

	/*
	 * If the destination buffer is unaligned, start with reading
	 * the overlap byte-wise.
	 */
	head = ((uint32_t) buf) % 4;
	if (head) {
		omap_nand_read(mtd, buf, head);
		buf += head;
		len -= head;
	}

	/*
	 * Only transfer multiples of 4 bytes in a pre-fetched fashion.
	 * If there's a residue, care for it byte-wise afterwards.
	 */
	tail = len % 4;

	ret = __read_prefetch_aligned(chip, (uint32_t *)buf, len - tail);
	if (ret < 0) {
		/* fallback in case the prefetch engine is busy */
		omap_nand_read(mtd, buf, len);
	} else if (tail) {
		buf += len - tail;
		omap_nand_read(mtd, buf, tail);
	}
}
#endif /* CONFIG_NAND_OMAP_GPMC_PREFETCH */

#ifdef CONFIG_NAND_OMAP_ELM
/*
 * omap_reverse_list - re-orders list elements in reverse order [internal]
 * @list:	pointer to start of list
 * @length:	length of list
*/
static void omap_reverse_list(u8 *list, unsigned int length)
{
	unsigned int i, j;
	unsigned int half_length = length / 2;
	u8 tmp;
	for (i = 0, j = length - 1; i < half_length; i++, j--) {
		tmp = list[i];
		list[i] = list[j];
		list[j] = tmp;
	}
}

/*
 * omap_correct_data_bch - Compares the ecc read from nand spare area
 * with ECC registers values and corrects one bit error if it has occured
 *
 * @mtd:	MTD device structure
 * @dat:	page data
 * @read_ecc:	ecc read from nand flash (ignored)
 * @calc_ecc:	ecc read from ECC registers
 *
 * @return 0 if data is OK or corrected, else returns -1
 */
static int omap_correct_data_bch(struct mtd_info *mtd, uint8_t *dat,
				uint8_t *read_ecc, uint8_t *calc_ecc)
{
	struct nand_chip *chip = mtd->priv;
	struct omap_nand_info *info = chip->priv;
	struct nand_ecc_ctrl *ecc = &chip->ecc;
	uint32_t error_count = 0, error_max;
	uint32_t error_loc[ELM_MAX_ERROR_COUNT];
	enum bch_level bch_type;
	uint32_t i, ecc_flag = 0;
	uint8_t count;
	uint32_t byte_pos, bit_pos;
	int err = 0;

	/* check calculated ecc */
	for (i = 0; i < ecc->bytes && !ecc_flag; i++) {
		if (calc_ecc[i] != 0x00)
			ecc_flag = 1;
	}
	if (!ecc_flag)
		return 0;

	/* check for whether its a erased-page */
	ecc_flag = 0;
	for (i = 0; i < ecc->bytes && !ecc_flag; i++) {
		if (read_ecc[i] != 0xff)
			ecc_flag = 1;
	}
	if (!ecc_flag)
		return 0;

	/*
	 * while reading ECC result we read it in big endian.
	 * Hence while loading to ELM we have rotate to get the right endian.
	 */
	switch (info->ecc_scheme) {
	case OMAP_ECC_BCH8_CODE_HW:
		bch_type = BCH_8_BIT;
		omap_reverse_list(calc_ecc, ecc->bytes - 1);
		break;
	case OMAP_ECC_BCH16_CODE_HW:
		bch_type = BCH_16_BIT;
		omap_reverse_list(calc_ecc, ecc->bytes);
		break;
	default:
		return -EINVAL;
	}
	/* use elm module to check for errors */
	elm_config(bch_type);
	err = elm_check_error(calc_ecc, bch_type, &error_count, error_loc);
	if (err)
		return err;

	/* correct bch error */
	for (count = 0; count < error_count; count++) {
		switch (info->ecc_scheme) {
		case OMAP_ECC_BCH8_CODE_HW:
			/* 14th byte in ECC is reserved to match ROM layout */
			error_max = SECTOR_BYTES + (ecc->bytes - 1);
			break;
		case OMAP_ECC_BCH16_CODE_HW:
			error_max = SECTOR_BYTES + ecc->bytes;
			break;
		default:
			return -EINVAL;
		}
		byte_pos = error_max - (error_loc[count] / 8) - 1;
		bit_pos  = error_loc[count] % 8;
		if (byte_pos < SECTOR_BYTES) {
			dat[byte_pos] ^= 1 << bit_pos;
			printf("nand: bit-flip corrected @data=%d\n", byte_pos);
		} else if (byte_pos < error_max) {
			read_ecc[byte_pos - SECTOR_BYTES] ^= 1 << bit_pos;
			printf("nand: bit-flip corrected @oob=%d\n", byte_pos -
								SECTOR_BYTES);
		} else {
			err = -EBADMSG;
			printf("nand: error: invalid bit-flip location\n");
		}
	}
	return (err) ? err : error_count;
}

/**
 * omap_read_page_bch - hardware ecc based page read function
 * @mtd:	mtd info structure
 * @chip:	nand chip info structure
 * @buf:	buffer to store read data
 * @oob_required: caller expects OOB data read to chip->oob_poi
 * @page:	page number to read
 *
 */
static int omap_read_page_bch(struct mtd_info *mtd, struct nand_chip *chip,
				uint8_t *buf, int oob_required, int page)
{
	int i, eccsize = chip->ecc.size;
	int eccbytes = chip->ecc.bytes;
	int eccsteps = chip->ecc.steps;
	uint8_t *p = buf;
	uint8_t *ecc_calc = chip->buffers->ecccalc;
	uint8_t *ecc_code = chip->buffers->ecccode;
	uint32_t *eccpos = chip->ecc.layout->eccpos;
	uint8_t *oob = chip->oob_poi;
	uint32_t data_pos;
	uint32_t oob_pos;

	data_pos = 0;
	/* oob area start */
	oob_pos = (eccsize * eccsteps) + chip->ecc.layout->eccpos[0];
	oob += chip->ecc.layout->eccpos[0];

	for (i = 0; eccsteps; eccsteps--, i += eccbytes, p += eccsize,
				oob += eccbytes) {
		chip->ecc.hwctl(mtd, NAND_ECC_READ);
		/* read data */
		chip->cmdfunc(mtd, NAND_CMD_RNDOUT, data_pos, -1);
		chip->read_buf(mtd, p, eccsize);

		/* read respective ecc from oob area */
		chip->cmdfunc(mtd, NAND_CMD_RNDOUT, oob_pos, -1);
		chip->read_buf(mtd, oob, eccbytes);
		/* read syndrome */
		chip->ecc.calculate(mtd, p, &ecc_calc[i]);

		data_pos += eccsize;
		oob_pos += eccbytes;
	}

	for (i = 0; i < chip->ecc.total; i++)
		ecc_code[i] = chip->oob_poi[eccpos[i]];

	eccsteps = chip->ecc.steps;
	p = buf;

	for (i = 0 ; eccsteps; eccsteps--, i += eccbytes, p += eccsize) {
		int stat;

		stat = chip->ecc.correct(mtd, p, &ecc_code[i], &ecc_calc[i]);
		if (stat < 0)
			mtd->ecc_stats.failed++;
		else
			mtd->ecc_stats.corrected += stat;
	}
	return 0;
}
#endif /* CONFIG_NAND_OMAP_ELM */

/*
 * OMAP3 BCH8 support (with BCH library)
 */
#ifdef CONFIG_BCH
/**
 * omap_correct_data_bch_sw - Decode received data and correct errors
 * @mtd: MTD device structure
 * @data: page data
 * @read_ecc: ecc read from nand flash
 * @calc_ecc: ecc read from HW ECC registers
 */
static int omap_correct_data_bch_sw(struct mtd_info *mtd, u_char *data,
				 u_char *read_ecc, u_char *calc_ecc)
{
	int i, count;
	/* cannot correct more than 8 errors */
	unsigned int errloc[8];
	struct nand_chip *chip = mtd->priv;
	struct omap_nand_info *info = chip->priv;

	count = decode_bch(info->control, NULL, 512, read_ecc, calc_ecc,
							NULL, errloc);
	if (count > 0) {
		/* correct errors */
		for (i = 0; i < count; i++) {
			/* correct data only, not ecc bytes */
			if (errloc[i] < 8*512)
				data[errloc[i]/8] ^= 1 << (errloc[i] & 7);
			printf("corrected bitflip %u\n", errloc[i]);
#ifdef DEBUG
			puts("read_ecc: ");
			/*
			 * BCH8 have 13 bytes of ECC; BCH4 needs adoption
			 * here!
			 */
			for (i = 0; i < 13; i++)
				printf("%02x ", read_ecc[i]);
			puts("\n");
			puts("calc_ecc: ");
			for (i = 0; i < 13; i++)
				printf("%02x ", calc_ecc[i]);
			puts("\n");
#endif
		}
	} else if (count < 0) {
		puts("ecc unrecoverable error\n");
	}
	return count;
}

/**
 * omap_free_bch - Release BCH ecc resources
 * @mtd: MTD device structure
 */
static void __maybe_unused omap_free_bch(struct mtd_info *mtd)
{
	struct nand_chip *chip = mtd->priv;
	struct omap_nand_info *info = chip->priv;

	if (info->control) {
		free_bch(info->control);
		info->control = NULL;
	}
}
#endif /* CONFIG_BCH */

/**
 * omap_select_ecc_scheme - configures driver for particular ecc-scheme
 * @nand: NAND chip device structure
 * @ecc_scheme: ecc scheme to configure
 * @pagesize: number of main-area bytes per page of NAND device
 * @oobsize: number of OOB/spare bytes per page of NAND device
 */
static int omap_select_ecc_scheme(struct nand_chip *nand,
	enum omap_ecc ecc_scheme, unsigned int pagesize, unsigned int oobsize) {
	struct omap_nand_info	*info		= nand->priv;
	struct nand_ecclayout	*ecclayout	= &omap_ecclayout;
	int eccsteps = pagesize / SECTOR_BYTES;
	int i;

	switch (ecc_scheme) {
	case OMAP_ECC_HAM1_CODE_SW:
		debug("nand: selected OMAP_ECC_HAM1_CODE_SW\n");
		/* For this ecc-scheme, ecc.bytes, ecc.layout, ... are
		 * initialized in nand_scan_tail(), so just set ecc.mode */
		info->control		= NULL;
		nand->ecc.mode		= NAND_ECC_SOFT;
		nand->ecc.layout	= NULL;
		nand->ecc.size		= 0;
		break;

	case OMAP_ECC_HAM1_CODE_HW:
		debug("nand: selected OMAP_ECC_HAM1_CODE_HW\n");
		/* check ecc-scheme requirements before updating ecc info */
		if ((3 * eccsteps) + BADBLOCK_MARKER_LENGTH > oobsize) {
			printf("nand: error: insufficient OOB: require=%d\n", (
				(3 * eccsteps) + BADBLOCK_MARKER_LENGTH));
			return -EINVAL;
		}
		info->control		= NULL;
		/* populate ecc specific fields */
		memset(&nand->ecc, 0, sizeof(struct nand_ecc_ctrl));
		nand->ecc.mode		= NAND_ECC_HW;
		nand->ecc.strength	= 1;
		nand->ecc.size		= SECTOR_BYTES;
		nand->ecc.bytes		= 3;
		nand->ecc.hwctl		= omap_enable_hwecc;
		nand->ecc.correct	= omap_correct_data;
		nand->ecc.calculate	= omap_calculate_ecc;
		/* define ecc-layout */
		ecclayout->eccbytes	= nand->ecc.bytes * eccsteps;
		for (i = 0; i < ecclayout->eccbytes; i++) {
			if (nand->options & NAND_BUSWIDTH_16)
				ecclayout->eccpos[i] = i + 2;
			else
				ecclayout->eccpos[i] = i + 1;
		}
		ecclayout->oobfree[0].offset = i + BADBLOCK_MARKER_LENGTH;
		ecclayout->oobfree[0].length = oobsize - ecclayout->eccbytes -
						BADBLOCK_MARKER_LENGTH;
		break;

	case OMAP_ECC_BCH8_CODE_HW_DETECTION_SW:
#ifdef CONFIG_BCH
		debug("nand: selected OMAP_ECC_BCH8_CODE_HW_DETECTION_SW\n");
		/* check ecc-scheme requirements before updating ecc info */
		if ((13 * eccsteps) + BADBLOCK_MARKER_LENGTH > oobsize) {
			printf("nand: error: insufficient OOB: require=%d\n", (
				(13 * eccsteps) + BADBLOCK_MARKER_LENGTH));
			return -EINVAL;
		}
		/* check if BCH S/W library can be used for error detection */
		info->control = init_bch(13, 8, 0x201b);
		if (!info->control) {
			printf("nand: error: could not init_bch()\n");
			return -ENODEV;
		}
		/* populate ecc specific fields */
		memset(&nand->ecc, 0, sizeof(struct nand_ecc_ctrl));
		nand->ecc.mode		= NAND_ECC_HW;
		nand->ecc.strength	= 8;
		nand->ecc.size		= SECTOR_BYTES;
		nand->ecc.bytes		= 13;
		nand->ecc.hwctl		= omap_enable_hwecc;
		nand->ecc.correct	= omap_correct_data_bch_sw;
		nand->ecc.calculate	= omap_calculate_ecc;
		/* define ecc-layout */
		ecclayout->eccbytes	= nand->ecc.bytes * eccsteps;
		ecclayout->eccpos[0]	= BADBLOCK_MARKER_LENGTH;
		for (i = 1; i < ecclayout->eccbytes; i++) {
			if (i % nand->ecc.bytes)
				ecclayout->eccpos[i] =
						ecclayout->eccpos[i - 1] + 1;
			else
				ecclayout->eccpos[i] =
						ecclayout->eccpos[i - 1] + 2;
		}
		ecclayout->oobfree[0].offset = i + BADBLOCK_MARKER_LENGTH;
		ecclayout->oobfree[0].length = oobsize - ecclayout->eccbytes -
						BADBLOCK_MARKER_LENGTH;
		break;
#else
		printf("nand: error: CONFIG_BCH required for ECC\n");
		return -EINVAL;
#endif

	case OMAP_ECC_BCH8_CODE_HW:
#ifdef CONFIG_NAND_OMAP_ELM
		debug("nand: selected OMAP_ECC_BCH8_CODE_HW\n");
		/* check ecc-scheme requirements before updating ecc info */
		if ((14 * eccsteps) + BADBLOCK_MARKER_LENGTH > oobsize) {
			printf("nand: error: insufficient OOB: require=%d\n", (
				(14 * eccsteps) + BADBLOCK_MARKER_LENGTH));
			return -EINVAL;
		}
		/* intialize ELM for ECC error detection */
		elm_init();
		info->control		= NULL;
		/* populate ecc specific fields */
		memset(&nand->ecc, 0, sizeof(struct nand_ecc_ctrl));
		nand->ecc.mode		= NAND_ECC_HW;
		nand->ecc.strength	= 8;
		nand->ecc.size		= SECTOR_BYTES;
		nand->ecc.bytes		= 14;
		nand->ecc.hwctl		= omap_enable_hwecc;
		nand->ecc.correct	= omap_correct_data_bch;
		nand->ecc.calculate	= omap_calculate_ecc;
		nand->ecc.read_page	= omap_read_page_bch;
		/* define ecc-layout */
		ecclayout->eccbytes	= nand->ecc.bytes * eccsteps;
		for (i = 0; i < ecclayout->eccbytes; i++)
			ecclayout->eccpos[i] = i + BADBLOCK_MARKER_LENGTH;
		ecclayout->oobfree[0].offset = i + BADBLOCK_MARKER_LENGTH;
		ecclayout->oobfree[0].length = oobsize - ecclayout->eccbytes -
						BADBLOCK_MARKER_LENGTH;
		break;
#else
		printf("nand: error: CONFIG_NAND_OMAP_ELM required for ECC\n");
		return -EINVAL;
#endif

	case OMAP_ECC_BCH16_CODE_HW:
#ifdef CONFIG_NAND_OMAP_ELM
		debug("nand: using OMAP_ECC_BCH16_CODE_HW\n");
		/* check ecc-scheme requirements before updating ecc info */
		if ((26 * eccsteps) + BADBLOCK_MARKER_LENGTH > oobsize) {
			printf("nand: error: insufficient OOB: require=%d\n", (
				(26 * eccsteps) + BADBLOCK_MARKER_LENGTH));
			return -EINVAL;
		}
		/* intialize ELM for ECC error detection */
		elm_init();
		/* populate ecc specific fields */
		nand->ecc.mode		= NAND_ECC_HW;
		nand->ecc.size		= SECTOR_BYTES;
		nand->ecc.bytes		= 26;
		nand->ecc.strength	= 16;
		nand->ecc.hwctl		= omap_enable_hwecc;
		nand->ecc.correct	= omap_correct_data_bch;
		nand->ecc.calculate	= omap_calculate_ecc;
		nand->ecc.read_page	= omap_read_page_bch;
		/* define ecc-layout */
		ecclayout->eccbytes	= nand->ecc.bytes * eccsteps;
		for (i = 0; i < ecclayout->eccbytes; i++)
			ecclayout->eccpos[i] = i + BADBLOCK_MARKER_LENGTH;
		ecclayout->oobfree[0].offset = i + BADBLOCK_MARKER_LENGTH;
		ecclayout->oobfree[0].length = oobsize - nand->ecc.bytes -
						BADBLOCK_MARKER_LENGTH;
		break;
#else
		printf("nand: error: CONFIG_NAND_OMAP_ELM required for ECC\n");
		return -EINVAL;
#endif
	default:
		debug("nand: error: ecc scheme not enabled or supported\n");
		return -EINVAL;
	}

	/* nand_scan_tail() sets ham1 sw ecc; hw ecc layout is set by driver */
	if (ecc_scheme != OMAP_ECC_HAM1_CODE_SW)
		nand->ecc.layout = ecclayout;

	info->ecc_scheme = ecc_scheme;
	return 0;
}

#ifndef CONFIG_SPL_BUILD
/*
 * omap_nand_switch_ecc - switch the ECC operation between different engines
 * (h/w and s/w) and different algorithms (hamming and BCHx)
 *
 * @hardware		- true if one of the HW engines should be used
 * @eccstrength		- the number of bits that could be corrected
 *			  (1 - hamming, 4 - BCH4, 8 - BCH8, 16 - BCH16)
 */
int __maybe_unused omap_nand_switch_ecc(uint32_t hardware, uint32_t eccstrength)
{
	struct nand_chip *nand;
	struct mtd_info *mtd;
	int err = 0;

	if (nand_curr_device < 0 ||
	    nand_curr_device >= CONFIG_SYS_MAX_NAND_DEVICE ||
	    !nand_info[nand_curr_device].name) {
		printf("nand: error: no NAND devices found\n");
		return -ENODEV;
	}

	mtd = &nand_info[nand_curr_device];
	nand = mtd->priv;
	nand->options |= NAND_OWN_BUFFERS;
	nand->options &= ~NAND_SUBPAGE_READ;
	/* Setup the ecc configurations again */
	if (hardware) {
		if (eccstrength == 1) {
			err = omap_select_ecc_scheme(nand,
					OMAP_ECC_HAM1_CODE_HW,
					mtd->writesize, mtd->oobsize);
		} else if (eccstrength == 8) {
			err = omap_select_ecc_scheme(nand,
					OMAP_ECC_BCH8_CODE_HW,
					mtd->writesize, mtd->oobsize);
		} else {
			printf("nand: error: unsupported ECC scheme\n");
			return -EINVAL;
		}
	} else {
		if (eccstrength == 1) {
			err = omap_select_ecc_scheme(nand,
					OMAP_ECC_HAM1_CODE_SW,
					mtd->writesize, mtd->oobsize);
		} else if (eccstrength == 8) {
			err = omap_select_ecc_scheme(nand,
					OMAP_ECC_BCH8_CODE_HW_DETECTION_SW,
					mtd->writesize, mtd->oobsize);
		} else {
			printf("nand: error: unsupported ECC scheme\n");
			return -EINVAL;
		}
	}

	/* Update NAND handling after ECC mode switch */
	if (!err)
		err = nand_scan_tail(mtd);
	return err;
}
#endif /* CONFIG_SPL_BUILD */

/*
 * Board-specific NAND initialization. The following members of the
 * argument are board-specific:
 * - IO_ADDR_R: address to read the 8 I/O lines of the flash device
 * - IO_ADDR_W: address to write the 8 I/O lines of the flash device
 * - cmd_ctrl: hardwarespecific function for accesing control-lines
 * - waitfunc: hardwarespecific function for accesing device ready/busy line
 * - ecc.hwctl: function to enable (reset) hardware ecc generator
 * - ecc.mode: mode of ecc, see defines
 * - chip_delay: chip dependent delay for transfering data from array to
 *   read regs (tR)
 * - options: various chip options. They can partly be set to inform
 *   nand_scan about special functionality. See the defines for further
 *   explanation
 */
int board_nand_init(struct nand_chip *nand)
{
	int32_t gpmc_config = 0;
	int cs = cs_next++;
	int err = 0;
	/*
	 * xloader/Uboot's gpmc configuration would have configured GPMC for
	 * nand type of memory. The following logic scans and latches on to the
	 * first CS with NAND type memory.
	 * TBD: need to make this logic generic to handle multiple CS NAND
	 * devices.
	 */
	while (cs < GPMC_MAX_CS) {
		/* Check if NAND type is set */
		if ((readl(&gpmc_cfg->cs[cs].config1) & 0xC00) == 0x800) {
			/* Found it!! */
			break;
		}
		cs++;
	}
	if (cs >= GPMC_MAX_CS) {
		printf("nand: error: Unable to find NAND settings in "
			"GPMC Configuration - quitting\n");
		return -ENODEV;
	}

	gpmc_config = readl(&gpmc_cfg->config);
	/* Disable Write protect */
	gpmc_config |= 0x10;
	writel(gpmc_config, &gpmc_cfg->config);

	nand->IO_ADDR_R = (void __iomem *)&gpmc_cfg->cs[cs].nand_dat;
	nand->IO_ADDR_W = (void __iomem *)&gpmc_cfg->cs[cs].nand_cmd;
	omap_nand_info[cs].control = NULL;
	omap_nand_info[cs].cs = cs;
	omap_nand_info[cs].ws = wscfg[cs];
	nand->priv	= &omap_nand_info[cs];
	nand->cmd_ctrl	= omap_nand_hwcontrol;
	nand->options	|= NAND_NO_PADDING | NAND_CACHEPRG;
	nand->chip_delay = 100;
	nand->ecc.layout = &omap_ecclayout;

	/* configure driver and controller based on NAND device bus-width */
	gpmc_config = readl(&gpmc_cfg->cs[cs].config1);
#if defined(CONFIG_SYS_NAND_BUSWIDTH_16BIT)
	nand->options |= NAND_BUSWIDTH_16;
	writel(gpmc_config | (0x1 << 12), &gpmc_cfg->cs[cs].config1);
#else
	nand->options &= ~NAND_BUSWIDTH_16;
	writel(gpmc_config & ~(0x1 << 12), &gpmc_cfg->cs[cs].config1);
#endif
	/* select ECC scheme */
#if defined(CONFIG_NAND_OMAP_ECCSCHEME)
	err = omap_select_ecc_scheme(nand, CONFIG_NAND_OMAP_ECCSCHEME,
			CONFIG_SYS_NAND_PAGE_SIZE, CONFIG_SYS_NAND_OOBSIZE);
#else
	/* pagesize and oobsize are not required to configure sw ecc-scheme */
	err = omap_select_ecc_scheme(nand, OMAP_ECC_HAM1_CODE_SW,
			0, 0);
#endif
	if (err)
		return err;

#ifdef CONFIG_NAND_OMAP_GPMC_PREFETCH
	nand->read_buf = omap_nand_read_prefetch;
#else
	if (nand->options & NAND_BUSWIDTH_16)
		nand->read_buf = nand_read_buf16;
	else
		nand->read_buf = nand_read_buf;
#endif

	nand->dev_ready = omap_dev_ready;

	return 0;
}