summaryrefslogtreecommitdiff
path: root/drivers/mtd/devices/m25p80.c
blob: c6e6d8e8ef7b6ff7dce4e2775b80a5a6e15e6629 (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
1135
1136
1137
1138
1139
1140
1141
1142
1143
1144
1145
1146
1147
1148
1149
1150
1151
1152
1153
1154
1155
1156
1157
1158
1159
1160
1161
1162
1163
1164
1165
1166
1167
1168
1169
1170
1171
1172
1173
1174
1175
1176
1177
1178
1179
1180
1181
1182
1183
1184
1185
1186
1187
1188
1189
1190
1191
1192
1193
1194
1195
1196
1197
1198
1199
1200
1201
1202
1203
1204
1205
1206
1207
1208
1209
1210
1211
1212
1213
1214
1215
1216
1217
1218
1219
1220
1221
1222
1223
1224
1225
1226
1227
1228
1229
1230
1231
1232
1233
1234
1235
1236
1237
1238
1239
1240
1241
1242
1243
1244
1245
1246
1247
1248
1249
1250
1251
1252
1253
1254
1255
1256
1257
1258
1259
1260
1261
1262
1263
1264
1265
1266
1267
1268
1269
1270
1271
1272
1273
1274
1275
1276
1277
1278
1279
1280
1281
1282
1283
1284
1285
1286
1287
1288
1289
1290
1291
1292
1293
1294
1295
1296
1297
1298
1299
1300
1301
1302
1303
1304
1305
1306
1307
1308
1309
1310
1311
1312
1313
1314
1315
1316
1317
1318
1319
1320
1321
1322
1323
1324
1325
1326
1327
1328
1329
1330
1331
1332
1333
1334
1335
1336
1337
1338
1339
1340
1341
1342
1343
1344
1345
1346
1347
1348
1349
1350
1351
1352
1353
1354
1355
1356
/*
 * MTD SPI driver for ST M25Pxx (and similar) serial flash chips
 *
 * Author: Mike Lavender, mike@steroidmicros.com
 *
 * Copyright (c) 2005, Intec Automation Inc.
 *
 * Some parts are based on lart.c by Abraham Van Der Merwe
 *
 * Cleaned up and generalized based on mtd_dataflash.c
 *
 * This code 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.
 *
 */

#include <linux/err.h>
#include <linux/errno.h>
#include <linux/module.h>
#include <linux/device.h>
#include <linux/interrupt.h>
#include <linux/mutex.h>
#include <linux/math64.h>
#include <linux/slab.h>
#include <linux/sched.h>
#include <linux/mod_devicetable.h>

#include <linux/mtd/cfi.h>
#include <linux/mtd/mtd.h>
#include <linux/mtd/partitions.h>
#include <linux/of_platform.h>

#include <linux/spi/spi.h>
#include <linux/spi/flash.h>

/* Flash opcodes. */
#define	OPCODE_WREN		0x06	/* Write enable */
#define	OPCODE_RDSR		0x05	/* Read status register */
#define	OPCODE_WRSR		0x01	/* Write status register 1 byte */
#define	OPCODE_NORM_READ	0x03	/* Read data bytes (low frequency) */
#define	OPCODE_FAST_READ	0x0b	/* Read data bytes (high frequency) */
#define	OPCODE_DUAL_READ        0x3b    /* Read data bytes (Dual SPI) */
#define	OPCODE_QUAD_READ        0x6b    /* Read data bytes (Quad SPI) */
#define	OPCODE_PP		0x02	/* Page program (up to 256 bytes) */
#define	OPCODE_BE_4K		0x20	/* Erase 4KiB block */
#define	OPCODE_BE_4K_PMC	0xd7	/* Erase 4KiB block on PMC chips */
#define	OPCODE_BE_32K		0x52	/* Erase 32KiB block */
#define	OPCODE_CHIP_ERASE	0xc7	/* Erase whole flash chip */
#define	OPCODE_SE		0xd8	/* Sector erase (usually 64KiB) */
#define	OPCODE_RDID		0x9f	/* Read JEDEC ID */
#define	OPCODE_RDCR             0x35    /* Read configuration register */

/* 4-byte address opcodes - used on Spansion and some Macronix flashes. */
#define	OPCODE_NORM_READ_4B	0x13	/* Read data bytes (low frequency) */
#define	OPCODE_FAST_READ_4B	0x0c	/* Read data bytes (high frequency) */
#define	OPCODE_DUAL_READ_4B	0x3c    /* Read data bytes (Dual SPI) */
#define	OPCODE_QUAD_READ_4B	0x6c    /* Read data bytes (Quad SPI) */
#define	OPCODE_PP_4B		0x12	/* Page program (up to 256 bytes) */
#define	OPCODE_SE_4B		0xdc	/* Sector erase (usually 64KiB) */

/* Used for SST flashes only. */
#define	OPCODE_BP		0x02	/* Byte program */
#define	OPCODE_WRDI		0x04	/* Write disable */
#define	OPCODE_AAI_WP		0xad	/* Auto address increment word program */

/* Used for Macronix and Winbond flashes. */
#define	OPCODE_EN4B		0xb7	/* Enter 4-byte mode */
#define	OPCODE_EX4B		0xe9	/* Exit 4-byte mode */

/* Used for Spansion flashes only. */
#define	OPCODE_BRWR		0x17	/* Bank register write */

/* Status Register bits. */
#define	SR_WIP			1	/* Write in progress */
#define	SR_WEL			2	/* Write enable latch */
/* meaning of other SR_* bits may differ between vendors */
#define	SR_BP0			4	/* Block protect 0 */
#define	SR_BP1			8	/* Block protect 1 */
#define	SR_BP2			0x10	/* Block protect 2 */
#define	SR_SRWD			0x80	/* SR write protect */

#define SR_QUAD_EN_MX           0x40    /* Macronix Quad I/O */

/* Configuration Register bits. */
#define CR_QUAD_EN_SPAN		0x2     /* Spansion Quad I/O */

/* Define max times to check status register before we give up. */
#define	MAX_READY_WAIT_JIFFIES	(40 * HZ)	/* M25P16 specs 40s max chip erase */
#define	MAX_CMD_SIZE		6

#define JEDEC_MFR(_jedec_id)	((_jedec_id) >> 16)

/****************************************************************************/

enum read_type {
	M25P80_NORMAL = 0,
	M25P80_FAST,
	M25P80_DUAL,
	M25P80_QUAD,
};

struct m25p {
	struct spi_device	*spi;
	struct mutex		lock;
	struct mtd_info		mtd;
	u16			page_size;
	u16			addr_width;
	u8			erase_opcode;
	u8			read_opcode;
	u8			program_opcode;
	u8			*command;
	enum read_type		flash_read;
};

static inline struct m25p *mtd_to_m25p(struct mtd_info *mtd)
{
	return container_of(mtd, struct m25p, mtd);
}

/****************************************************************************/

/*
 * Internal helper functions
 */

/*
 * Read the status register, returning its value in the location
 * Return the status register value.
 * Returns negative if error occurred.
 */
static int read_sr(struct m25p *flash)
{
	ssize_t retval;
	u8 code = OPCODE_RDSR;
	u8 val;

	retval = spi_write_then_read(flash->spi, &code, 1, &val, 1);

	if (retval < 0) {
		dev_err(&flash->spi->dev, "error %d reading SR\n",
				(int) retval);
		return retval;
	}

	return val;
}

/*
 * Read configuration register, returning its value in the
 * location. Return the configuration register value.
 * Returns negative if error occured.
 */
static int read_cr(struct m25p *flash)
{
	u8 code = OPCODE_RDCR;
	int ret;
	u8 val;

	ret = spi_write_then_read(flash->spi, &code, 1, &val, 1);
	if (ret < 0) {
		dev_err(&flash->spi->dev, "error %d reading CR\n", ret);
		return ret;
	}

	return val;
}

/*
 * Write status register 1 byte
 * Returns negative if error occurred.
 */
static int write_sr(struct m25p *flash, u8 val)
{
	flash->command[0] = OPCODE_WRSR;
	flash->command[1] = val;

	return spi_write(flash->spi, flash->command, 2);
}

/*
 * Set write enable latch with Write Enable command.
 * Returns negative if error occurred.
 */
static inline int write_enable(struct m25p *flash)
{
	u8	code = OPCODE_WREN;

	return spi_write_then_read(flash->spi, &code, 1, NULL, 0);
}

/*
 * Send write disble instruction to the chip.
 */
static inline int write_disable(struct m25p *flash)
{
	u8	code = OPCODE_WRDI;

	return spi_write_then_read(flash->spi, &code, 1, NULL, 0);
}

/*
 * Enable/disable 4-byte addressing mode.
 */
static inline int set_4byte(struct m25p *flash, u32 jedec_id, int enable)
{
	int status;
	bool need_wren = false;

	switch (JEDEC_MFR(jedec_id)) {
	case CFI_MFR_ST: /* Micron, actually */
		/* Some Micron need WREN command; all will accept it */
		need_wren = true;
	case CFI_MFR_MACRONIX:
	case 0xEF /* winbond */:
		if (need_wren)
			write_enable(flash);

		flash->command[0] = enable ? OPCODE_EN4B : OPCODE_EX4B;
		status = spi_write(flash->spi, flash->command, 1);

		if (need_wren)
			write_disable(flash);

		return status;
	default:
		/* Spansion style */
		flash->command[0] = OPCODE_BRWR;
		flash->command[1] = enable << 7;
		return spi_write(flash->spi, flash->command, 2);
	}
}

/*
 * Service routine to read status register until ready, or timeout occurs.
 * Returns non-zero if error.
 */
static int wait_till_ready(struct m25p *flash)
{
	unsigned long deadline;
	int sr;

	deadline = jiffies + MAX_READY_WAIT_JIFFIES;

	do {
		if ((sr = read_sr(flash)) < 0)
			break;
		else if (!(sr & SR_WIP))
			return 0;

		cond_resched();

	} while (!time_after_eq(jiffies, deadline));

	return 1;
}

/*
 * Write status Register and configuration register with 2 bytes
 * The first byte will be written to the status register, while the
 * second byte will be written to the configuration register.
 * Return negative if error occured.
 */
static int write_sr_cr(struct m25p *flash, u16 val)
{
	flash->command[0] = OPCODE_WRSR;
	flash->command[1] = val & 0xff;
	flash->command[2] = (val >> 8);

	return spi_write(flash->spi, flash->command, 3);
}

static int macronix_quad_enable(struct m25p *flash)
{
	int ret, val;
	u8 cmd[2];
	cmd[0] = OPCODE_WRSR;

	val = read_sr(flash);
	cmd[1] = val | SR_QUAD_EN_MX;
	write_enable(flash);

	spi_write(flash->spi, &cmd, 2);

	if (wait_till_ready(flash))
		return 1;

	ret = read_sr(flash);
	if (!(ret > 0 && (ret & SR_QUAD_EN_MX))) {
		dev_err(&flash->spi->dev, "Macronix Quad bit not set\n");
		return -EINVAL;
	}

	return 0;
}

static int spansion_quad_enable(struct m25p *flash)
{
	int ret;
	int quad_en = CR_QUAD_EN_SPAN << 8;

	write_enable(flash);

	ret = write_sr_cr(flash, quad_en);
	if (ret < 0) {
		dev_err(&flash->spi->dev,
			"error while writing configuration register\n");
		return -EINVAL;
	}

	/* read back and check it */
	ret = read_cr(flash);
	if (!(ret > 0 && (ret & CR_QUAD_EN_SPAN))) {
		dev_err(&flash->spi->dev, "Spansion Quad bit not set\n");
		return -EINVAL;
	}

	return 0;
}

static int set_quad_mode(struct m25p *flash, u32 jedec_id)
{
	int status;

	switch (JEDEC_MFR(jedec_id)) {
	case CFI_MFR_MACRONIX:
		status = macronix_quad_enable(flash);
		if (status) {
			dev_err(&flash->spi->dev,
				"Macronix quad-read not enabled\n");
			return -EINVAL;
		}
		return status;
	default:
		status = spansion_quad_enable(flash);
		if (status) {
			dev_err(&flash->spi->dev,
				"Spansion quad-read not enabled\n");
			return -EINVAL;
		}
		return status;
	}
}

/*
 * Erase the whole flash memory
 *
 * Returns 0 if successful, non-zero otherwise.
 */
static int erase_chip(struct m25p *flash)
{
	pr_debug("%s: %s %lldKiB\n", dev_name(&flash->spi->dev), __func__,
			(long long)(flash->mtd.size >> 10));

	/* Wait until finished previous write command. */
	if (wait_till_ready(flash))
		return 1;

	/* Send write enable, then erase commands. */
	write_enable(flash);

	/* Set up command buffer. */
	flash->command[0] = OPCODE_CHIP_ERASE;

	spi_write(flash->spi, flash->command, 1);

	return 0;
}

static void m25p_addr2cmd(struct m25p *flash, unsigned int addr, u8 *cmd)
{
	/* opcode is in cmd[0] */
	cmd[1] = addr >> (flash->addr_width * 8 -  8);
	cmd[2] = addr >> (flash->addr_width * 8 - 16);
	cmd[3] = addr >> (flash->addr_width * 8 - 24);
	cmd[4] = addr >> (flash->addr_width * 8 - 32);
}

static int m25p_cmdsz(struct m25p *flash)
{
	return 1 + flash->addr_width;
}

/*
 * Erase one sector of flash memory at offset ``offset'' which is any
 * address within the sector which should be erased.
 *
 * Returns 0 if successful, non-zero otherwise.
 */
static int erase_sector(struct m25p *flash, u32 offset)
{
	pr_debug("%s: %s %dKiB at 0x%08x\n", dev_name(&flash->spi->dev),
			__func__, flash->mtd.erasesize / 1024, offset);

	/* Wait until finished previous write command. */
	if (wait_till_ready(flash))
		return 1;

	/* Send write enable, then erase commands. */
	write_enable(flash);

	/* Set up command buffer. */
	flash->command[0] = flash->erase_opcode;
	m25p_addr2cmd(flash, offset, flash->command);

	spi_write(flash->spi, flash->command, m25p_cmdsz(flash));

	return 0;
}

/****************************************************************************/

/*
 * MTD implementation
 */

/*
 * Erase an address range on the flash chip.  The address range may extend
 * one or more erase sectors.  Return an error is there is a problem erasing.
 */
static int m25p80_erase(struct mtd_info *mtd, struct erase_info *instr)
{
	struct m25p *flash = mtd_to_m25p(mtd);
	u32 addr,len;
	uint32_t rem;

	pr_debug("%s: %s at 0x%llx, len %lld\n", dev_name(&flash->spi->dev),
			__func__, (long long)instr->addr,
			(long long)instr->len);

	div_u64_rem(instr->len, mtd->erasesize, &rem);
	if (rem)
		return -EINVAL;

	addr = instr->addr;
	len = instr->len;

	mutex_lock(&flash->lock);

	/* whole-chip erase? */
	if (len == flash->mtd.size) {
		if (erase_chip(flash)) {
			instr->state = MTD_ERASE_FAILED;
			mutex_unlock(&flash->lock);
			return -EIO;
		}

	/* REVISIT in some cases we could speed up erasing large regions
	 * by using OPCODE_SE instead of OPCODE_BE_4K.  We may have set up
	 * to use "small sector erase", but that's not always optimal.
	 */

	/* "sector"-at-a-time erase */
	} else {
		while (len) {
			if (erase_sector(flash, addr)) {
				instr->state = MTD_ERASE_FAILED;
				mutex_unlock(&flash->lock);
				return -EIO;
			}

			addr += mtd->erasesize;
			len -= mtd->erasesize;
		}
	}

	mutex_unlock(&flash->lock);

	instr->state = MTD_ERASE_DONE;
	mtd_erase_callback(instr);

	return 0;
}

/*
 * Dummy Cycle calculation for different type of read.
 * It can be used to support more commands with
 * different dummy cycle requirements.
 */
static inline int m25p80_dummy_cycles_read(struct m25p *flash)
{
	switch (flash->flash_read) {
	case M25P80_FAST:
	case M25P80_DUAL:
	case M25P80_QUAD:
		return 1;
	case M25P80_NORMAL:
		return 0;
	default:
		dev_err(&flash->spi->dev, "No valid read type supported\n");
		return -1;
	}
}

static inline unsigned int m25p80_rx_nbits(const struct m25p *flash)
{
	switch (flash->flash_read) {
	case M25P80_DUAL:
		return 2;
	case M25P80_QUAD:
		return 4;
	default:
		return 0;
	}
}

/*
 * Read an address range from the flash chip.  The address range
 * may be any size provided it is within the physical boundaries.
 */
static int m25p80_read(struct mtd_info *mtd, loff_t from, size_t len,
	size_t *retlen, u_char *buf)
{
	struct m25p *flash = mtd_to_m25p(mtd);
	struct spi_transfer t[2];
	struct spi_message m;
	uint8_t opcode;
	int dummy;

	pr_debug("%s: %s from 0x%08x, len %zd\n", dev_name(&flash->spi->dev),
			__func__, (u32)from, len);

	spi_message_init(&m);
	memset(t, 0, (sizeof t));

	dummy =  m25p80_dummy_cycles_read(flash);
	if (dummy < 0) {
		dev_err(&flash->spi->dev, "No valid read command supported\n");
		return -EINVAL;
	}

	t[0].tx_buf = flash->command;
	t[0].len = m25p_cmdsz(flash) + dummy;
	spi_message_add_tail(&t[0], &m);

	t[1].rx_buf = buf;
	t[1].rx_nbits = m25p80_rx_nbits(flash);
	t[1].len = len;
	spi_message_add_tail(&t[1], &m);

	mutex_lock(&flash->lock);

	/* Wait till previous write/erase is done. */
	if (wait_till_ready(flash)) {
		/* REVISIT status return?? */
		mutex_unlock(&flash->lock);
		return 1;
	}

	/* Set up the write data buffer. */
	opcode = flash->read_opcode;
	flash->command[0] = opcode;
	m25p_addr2cmd(flash, from, flash->command);

	spi_sync(flash->spi, &m);

	*retlen = m.actual_length - m25p_cmdsz(flash) - dummy;

	mutex_unlock(&flash->lock);

	return 0;
}

/*
 * Write an address range to the flash chip.  Data must be written in
 * FLASH_PAGESIZE chunks.  The address range may be any size provided
 * it is within the physical boundaries.
 */
static int m25p80_write(struct mtd_info *mtd, loff_t to, size_t len,
	size_t *retlen, const u_char *buf)
{
	struct m25p *flash = mtd_to_m25p(mtd);
	u32 page_offset, page_size;
	struct spi_transfer t[2];
	struct spi_message m;

	pr_debug("%s: %s to 0x%08x, len %zd\n", dev_name(&flash->spi->dev),
			__func__, (u32)to, len);

	spi_message_init(&m);
	memset(t, 0, (sizeof t));

	t[0].tx_buf = flash->command;
	t[0].len = m25p_cmdsz(flash);
	spi_message_add_tail(&t[0], &m);

	t[1].tx_buf = buf;
	spi_message_add_tail(&t[1], &m);

	mutex_lock(&flash->lock);

	/* Wait until finished previous write command. */
	if (wait_till_ready(flash)) {
		mutex_unlock(&flash->lock);
		return 1;
	}

	write_enable(flash);

	/* Set up the opcode in the write buffer. */
	flash->command[0] = flash->program_opcode;
	m25p_addr2cmd(flash, to, flash->command);

	page_offset = to & (flash->page_size - 1);

	/* do all the bytes fit onto one page? */
	if (page_offset + len <= flash->page_size) {
		t[1].len = len;

		spi_sync(flash->spi, &m);

		*retlen = m.actual_length - m25p_cmdsz(flash);
	} else {
		u32 i;

		/* the size of data remaining on the first page */
		page_size = flash->page_size - page_offset;

		t[1].len = page_size;
		spi_sync(flash->spi, &m);

		*retlen = m.actual_length - m25p_cmdsz(flash);

		/* write everything in flash->page_size chunks */
		for (i = page_size; i < len; i += page_size) {
			page_size = len - i;
			if (page_size > flash->page_size)
				page_size = flash->page_size;

			/* write the next page to flash */
			m25p_addr2cmd(flash, to + i, flash->command);

			t[1].tx_buf = buf + i;
			t[1].len = page_size;

			wait_till_ready(flash);

			write_enable(flash);

			spi_sync(flash->spi, &m);

			*retlen += m.actual_length - m25p_cmdsz(flash);
		}
	}

	mutex_unlock(&flash->lock);

	return 0;
}

static int sst_write(struct mtd_info *mtd, loff_t to, size_t len,
		size_t *retlen, const u_char *buf)
{
	struct m25p *flash = mtd_to_m25p(mtd);
	struct spi_transfer t[2];
	struct spi_message m;
	size_t actual;
	int cmd_sz, ret;

	pr_debug("%s: %s to 0x%08x, len %zd\n", dev_name(&flash->spi->dev),
			__func__, (u32)to, len);

	spi_message_init(&m);
	memset(t, 0, (sizeof t));

	t[0].tx_buf = flash->command;
	t[0].len = m25p_cmdsz(flash);
	spi_message_add_tail(&t[0], &m);

	t[1].tx_buf = buf;
	spi_message_add_tail(&t[1], &m);

	mutex_lock(&flash->lock);

	/* Wait until finished previous write command. */
	ret = wait_till_ready(flash);
	if (ret)
		goto time_out;

	write_enable(flash);

	actual = to % 2;
	/* Start write from odd address. */
	if (actual) {
		flash->command[0] = OPCODE_BP;
		m25p_addr2cmd(flash, to, flash->command);

		/* write one byte. */
		t[1].len = 1;
		spi_sync(flash->spi, &m);
		ret = wait_till_ready(flash);
		if (ret)
			goto time_out;
		*retlen += m.actual_length - m25p_cmdsz(flash);
	}
	to += actual;

	flash->command[0] = OPCODE_AAI_WP;
	m25p_addr2cmd(flash, to, flash->command);

	/* Write out most of the data here. */
	cmd_sz = m25p_cmdsz(flash);
	for (; actual < len - 1; actual += 2) {
		t[0].len = cmd_sz;
		/* write two bytes. */
		t[1].len = 2;
		t[1].tx_buf = buf + actual;

		spi_sync(flash->spi, &m);
		ret = wait_till_ready(flash);
		if (ret)
			goto time_out;
		*retlen += m.actual_length - cmd_sz;
		cmd_sz = 1;
		to += 2;
	}
	write_disable(flash);
	ret = wait_till_ready(flash);
	if (ret)
		goto time_out;

	/* Write out trailing byte if it exists. */
	if (actual != len) {
		write_enable(flash);
		flash->command[0] = OPCODE_BP;
		m25p_addr2cmd(flash, to, flash->command);
		t[0].len = m25p_cmdsz(flash);
		t[1].len = 1;
		t[1].tx_buf = buf + actual;

		spi_sync(flash->spi, &m);
		ret = wait_till_ready(flash);
		if (ret)
			goto time_out;
		*retlen += m.actual_length - m25p_cmdsz(flash);
		write_disable(flash);
	}

time_out:
	mutex_unlock(&flash->lock);
	return ret;
}

static int m25p80_lock(struct mtd_info *mtd, loff_t ofs, uint64_t len)
{
	struct m25p *flash = mtd_to_m25p(mtd);
	uint32_t offset = ofs;
	uint8_t status_old, status_new;
	int res = 0;

	mutex_lock(&flash->lock);
	/* Wait until finished previous command */
	if (wait_till_ready(flash)) {
		res = 1;
		goto err;
	}

	status_old = read_sr(flash);

	if (offset < flash->mtd.size-(flash->mtd.size/2))
		status_new = status_old | SR_BP2 | SR_BP1 | SR_BP0;
	else if (offset < flash->mtd.size-(flash->mtd.size/4))
		status_new = (status_old & ~SR_BP0) | SR_BP2 | SR_BP1;
	else if (offset < flash->mtd.size-(flash->mtd.size/8))
		status_new = (status_old & ~SR_BP1) | SR_BP2 | SR_BP0;
	else if (offset < flash->mtd.size-(flash->mtd.size/16))
		status_new = (status_old & ~(SR_BP0|SR_BP1)) | SR_BP2;
	else if (offset < flash->mtd.size-(flash->mtd.size/32))
		status_new = (status_old & ~SR_BP2) | SR_BP1 | SR_BP0;
	else if (offset < flash->mtd.size-(flash->mtd.size/64))
		status_new = (status_old & ~(SR_BP2|SR_BP0)) | SR_BP1;
	else
		status_new = (status_old & ~(SR_BP2|SR_BP1)) | SR_BP0;

	/* Only modify protection if it will not unlock other areas */
	if ((status_new&(SR_BP2|SR_BP1|SR_BP0)) >
					(status_old&(SR_BP2|SR_BP1|SR_BP0))) {
		write_enable(flash);
		if (write_sr(flash, status_new) < 0) {
			res = 1;
			goto err;
		}
	}

err:	mutex_unlock(&flash->lock);
	return res;
}

static int m25p80_unlock(struct mtd_info *mtd, loff_t ofs, uint64_t len)
{
	struct m25p *flash = mtd_to_m25p(mtd);
	uint32_t offset = ofs;
	uint8_t status_old, status_new;
	int res = 0;

	mutex_lock(&flash->lock);
	/* Wait until finished previous command */
	if (wait_till_ready(flash)) {
		res = 1;
		goto err;
	}

	status_old = read_sr(flash);

	if (offset+len > flash->mtd.size-(flash->mtd.size/64))
		status_new = status_old & ~(SR_BP2|SR_BP1|SR_BP0);
	else if (offset+len > flash->mtd.size-(flash->mtd.size/32))
		status_new = (status_old & ~(SR_BP2|SR_BP1)) | SR_BP0;
	else if (offset+len > flash->mtd.size-(flash->mtd.size/16))
		status_new = (status_old & ~(SR_BP2|SR_BP0)) | SR_BP1;
	else if (offset+len > flash->mtd.size-(flash->mtd.size/8))
		status_new = (status_old & ~SR_BP2) | SR_BP1 | SR_BP0;
	else if (offset+len > flash->mtd.size-(flash->mtd.size/4))
		status_new = (status_old & ~(SR_BP0|SR_BP1)) | SR_BP2;
	else if (offset+len > flash->mtd.size-(flash->mtd.size/2))
		status_new = (status_old & ~SR_BP1) | SR_BP2 | SR_BP0;
	else
		status_new = (status_old & ~SR_BP0) | SR_BP2 | SR_BP1;

	/* Only modify protection if it will not lock other areas */
	if ((status_new&(SR_BP2|SR_BP1|SR_BP0)) <
					(status_old&(SR_BP2|SR_BP1|SR_BP0))) {
		write_enable(flash);
		if (write_sr(flash, status_new) < 0) {
			res = 1;
			goto err;
		}
	}

err:	mutex_unlock(&flash->lock);
	return res;
}

/****************************************************************************/

/*
 * SPI device driver setup and teardown
 */

struct flash_info {
	/* JEDEC id zero means "no ID" (most older chips); otherwise it has
	 * a high byte of zero plus three data bytes: the manufacturer id,
	 * then a two byte device id.
	 */
	u32		jedec_id;
	u16             ext_id;

	/* The size listed here is what works with OPCODE_SE, which isn't
	 * necessarily called a "sector" by the vendor.
	 */
	unsigned	sector_size;
	u16		n_sectors;

	u16		page_size;
	u16		addr_width;

	u16		flags;
#define	SECT_4K		0x01		/* OPCODE_BE_4K works uniformly */
#define	M25P_NO_ERASE	0x02		/* No erase command needed */
#define	SST_WRITE	0x04		/* use SST byte programming */
#define	M25P_NO_FR	0x08		/* Can't do fastread */
#define	SECT_4K_PMC	0x10		/* OPCODE_BE_4K_PMC works uniformly */
#define	M25P80_DUAL_READ	0x20    /* Flash supports Dual Read */
#define	M25P80_QUAD_READ	0x40    /* Flash supports Quad Read */
};

#define INFO(_jedec_id, _ext_id, _sector_size, _n_sectors, _flags)	\
	((kernel_ulong_t)&(struct flash_info) {				\
		.jedec_id = (_jedec_id),				\
		.ext_id = (_ext_id),					\
		.sector_size = (_sector_size),				\
		.n_sectors = (_n_sectors),				\
		.page_size = 256,					\
		.flags = (_flags),					\
	})

#define CAT25_INFO(_sector_size, _n_sectors, _page_size, _addr_width, _flags)	\
	((kernel_ulong_t)&(struct flash_info) {				\
		.sector_size = (_sector_size),				\
		.n_sectors = (_n_sectors),				\
		.page_size = (_page_size),				\
		.addr_width = (_addr_width),				\
		.flags = (_flags),					\
	})

/* NOTE: double check command sets and memory organization when you add
 * more flash chips.  This current list focusses on newer chips, which
 * have been converging on command sets which including JEDEC ID.
 */
static const struct spi_device_id m25p_ids[] = {
	/* Atmel -- some are (confusingly) marketed as "DataFlash" */
	{ "at25fs010",  INFO(0x1f6601, 0, 32 * 1024,   4, SECT_4K) },
	{ "at25fs040",  INFO(0x1f6604, 0, 64 * 1024,   8, SECT_4K) },

	{ "at25df041a", INFO(0x1f4401, 0, 64 * 1024,   8, SECT_4K) },
	{ "at25df321a", INFO(0x1f4701, 0, 64 * 1024,  64, SECT_4K) },
	{ "at25df641",  INFO(0x1f4800, 0, 64 * 1024, 128, SECT_4K) },

	{ "at26f004",   INFO(0x1f0400, 0, 64 * 1024,  8, SECT_4K) },
	{ "at26df081a", INFO(0x1f4501, 0, 64 * 1024, 16, SECT_4K) },
	{ "at26df161a", INFO(0x1f4601, 0, 64 * 1024, 32, SECT_4K) },
	{ "at26df321",  INFO(0x1f4700, 0, 64 * 1024, 64, SECT_4K) },

	{ "at45db081d", INFO(0x1f2500, 0, 64 * 1024, 16, SECT_4K) },

	/* EON -- en25xxx */
	{ "en25f32",    INFO(0x1c3116, 0, 64 * 1024,   64, SECT_4K) },
	{ "en25p32",    INFO(0x1c2016, 0, 64 * 1024,   64, 0) },
	{ "en25q32b",   INFO(0x1c3016, 0, 64 * 1024,   64, 0) },
	{ "en25p64",    INFO(0x1c2017, 0, 64 * 1024,  128, 0) },
	{ "en25q64",    INFO(0x1c3017, 0, 64 * 1024,  128, SECT_4K) },
	{ "en25qh256",  INFO(0x1c7019, 0, 64 * 1024,  512, 0) },

	/* ESMT */
	{ "f25l32pa", INFO(0x8c2016, 0, 64 * 1024, 64, SECT_4K) },

	/* Everspin */
	{ "mr25h256", CAT25_INFO( 32 * 1024, 1, 256, 2, M25P_NO_ERASE | M25P_NO_FR) },
	{ "mr25h10",  CAT25_INFO(128 * 1024, 1, 256, 3, M25P_NO_ERASE | M25P_NO_FR) },

	/* GigaDevice */
	{ "gd25q32", INFO(0xc84016, 0, 64 * 1024,  64, SECT_4K) },
	{ "gd25q64", INFO(0xc84017, 0, 64 * 1024, 128, SECT_4K) },

	/* Intel/Numonyx -- xxxs33b */
	{ "160s33b",  INFO(0x898911, 0, 64 * 1024,  32, 0) },
	{ "320s33b",  INFO(0x898912, 0, 64 * 1024,  64, 0) },
	{ "640s33b",  INFO(0x898913, 0, 64 * 1024, 128, 0) },

	/* Macronix */
	{ "mx25l2005a",  INFO(0xc22012, 0, 64 * 1024,   4, SECT_4K) },
	{ "mx25l4005a",  INFO(0xc22013, 0, 64 * 1024,   8, SECT_4K) },
	{ "mx25l8005",   INFO(0xc22014, 0, 64 * 1024,  16, 0) },
	{ "mx25l1606e",  INFO(0xc22015, 0, 64 * 1024,  32, SECT_4K) },
	{ "mx25l3205d",  INFO(0xc22016, 0, 64 * 1024,  64, 0) },
	{ "mx25l3255e",  INFO(0xc29e16, 0, 64 * 1024,  64, SECT_4K) },
	{ "mx25l6405d",  INFO(0xc22017, 0, 64 * 1024, 128, 0) },
	{ "mx25l12805d", INFO(0xc22018, 0, 64 * 1024, 256, 0) },
	{ "mx25l12855e", INFO(0xc22618, 0, 64 * 1024, 256, 0) },
	{ "mx25l25635e", INFO(0xc22019, 0, 64 * 1024, 512, 0) },
	{ "mx25l25655e", INFO(0xc22619, 0, 64 * 1024, 512, 0) },
	{ "mx66l51235l", INFO(0xc2201a, 0, 64 * 1024, 1024, M25P80_QUAD_READ) },

	/* Micron */
	{ "n25q064",     INFO(0x20ba17, 0, 64 * 1024,  128, 0) },
	{ "n25q128a11",  INFO(0x20bb18, 0, 64 * 1024,  256, 0) },
	{ "n25q128a13",  INFO(0x20ba18, 0, 64 * 1024,  256, 0) },
	{ "n25q256a",    INFO(0x20ba19, 0, 64 * 1024,  512, SECT_4K) },
	{ "n25q512a",    INFO(0x20bb20, 0, 64 * 1024, 1024, SECT_4K) },

	/* PMC */
	{ "pm25lv512",   INFO(0,        0, 32 * 1024,    2, SECT_4K_PMC) },
	{ "pm25lv010",   INFO(0,        0, 32 * 1024,    4, SECT_4K_PMC) },
	{ "pm25lq032",   INFO(0x7f9d46, 0, 64 * 1024,   64, SECT_4K) },

	/* Spansion -- single (large) sector size only, at least
	 * for the chips listed here (without boot sectors).
	 */
	{ "s25sl032p",  INFO(0x010215, 0x4d00,  64 * 1024,  64, 0) },
	{ "s25sl064p",  INFO(0x010216, 0x4d00,  64 * 1024, 128, 0) },
	{ "s25fl256s0", INFO(0x010219, 0x4d00, 256 * 1024, 128, 0) },
	{ "s25fl256s1", INFO(0x010219, 0x4d01,  64 * 1024, 512, M25P80_DUAL_READ | M25P80_QUAD_READ) },
	{ "s25fl512s",  INFO(0x010220, 0x4d00, 256 * 1024, 256, M25P80_DUAL_READ | M25P80_QUAD_READ) },
	{ "s70fl01gs",  INFO(0x010221, 0x4d00, 256 * 1024, 256, 0) },
	{ "s25sl12800", INFO(0x012018, 0x0300, 256 * 1024,  64, 0) },
	{ "s25sl12801", INFO(0x012018, 0x0301,  64 * 1024, 256, 0) },
	{ "s25fl129p0", INFO(0x012018, 0x4d00, 256 * 1024,  64, 0) },
	{ "s25fl129p1", INFO(0x012018, 0x4d01,  64 * 1024, 256, 0) },
	{ "s25sl004a",  INFO(0x010212,      0,  64 * 1024,   8, 0) },
	{ "s25sl008a",  INFO(0x010213,      0,  64 * 1024,  16, 0) },
	{ "s25sl016a",  INFO(0x010214,      0,  64 * 1024,  32, 0) },
	{ "s25sl032a",  INFO(0x010215,      0,  64 * 1024,  64, 0) },
	{ "s25sl064a",  INFO(0x010216,      0,  64 * 1024, 128, 0) },
	{ "s25fl016k",  INFO(0xef4015,      0,  64 * 1024,  32, SECT_4K) },
	{ "s25fl064k",  INFO(0xef4017,      0,  64 * 1024, 128, SECT_4K) },

	/* SST -- large erase sizes are "overlays", "sectors" are 4K */
	{ "sst25vf040b", INFO(0xbf258d, 0, 64 * 1024,  8, SECT_4K | SST_WRITE) },
	{ "sst25vf080b", INFO(0xbf258e, 0, 64 * 1024, 16, SECT_4K | SST_WRITE) },
	{ "sst25vf016b", INFO(0xbf2541, 0, 64 * 1024, 32, SECT_4K | SST_WRITE) },
	{ "sst25vf032b", INFO(0xbf254a, 0, 64 * 1024, 64, SECT_4K | SST_WRITE) },
	{ "sst25vf064c", INFO(0xbf254b, 0, 64 * 1024, 128, SECT_4K) },
	{ "sst25wf512",  INFO(0xbf2501, 0, 64 * 1024,  1, SECT_4K | SST_WRITE) },
	{ "sst25wf010",  INFO(0xbf2502, 0, 64 * 1024,  2, SECT_4K | SST_WRITE) },
	{ "sst25wf020",  INFO(0xbf2503, 0, 64 * 1024,  4, SECT_4K | SST_WRITE) },
	{ "sst25wf040",  INFO(0xbf2504, 0, 64 * 1024,  8, SECT_4K | SST_WRITE) },

	/* ST Microelectronics -- newer production may have feature updates */
	{ "m25p05",  INFO(0x202010,  0,  32 * 1024,   2, 0) },
	{ "m25p10",  INFO(0x202011,  0,  32 * 1024,   4, 0) },
	{ "m25p20",  INFO(0x202012,  0,  64 * 1024,   4, 0) },
	{ "m25p40",  INFO(0x202013,  0,  64 * 1024,   8, 0) },
	{ "m25p80",  INFO(0x202014,  0,  64 * 1024,  16, 0) },
	{ "m25p16",  INFO(0x202015,  0,  64 * 1024,  32, 0) },
	{ "m25p32",  INFO(0x202016,  0,  64 * 1024,  64, 0) },
	{ "m25p64",  INFO(0x202017,  0,  64 * 1024, 128, 0) },
	{ "m25p128", INFO(0x202018,  0, 256 * 1024,  64, 0) },
	{ "n25q032", INFO(0x20ba16,  0,  64 * 1024,  64, 0) },

	{ "m25p05-nonjedec",  INFO(0, 0,  32 * 1024,   2, 0) },
	{ "m25p10-nonjedec",  INFO(0, 0,  32 * 1024,   4, 0) },
	{ "m25p20-nonjedec",  INFO(0, 0,  64 * 1024,   4, 0) },
	{ "m25p40-nonjedec",  INFO(0, 0,  64 * 1024,   8, 0) },
	{ "m25p80-nonjedec",  INFO(0, 0,  64 * 1024,  16, 0) },
	{ "m25p16-nonjedec",  INFO(0, 0,  64 * 1024,  32, 0) },
	{ "m25p32-nonjedec",  INFO(0, 0,  64 * 1024,  64, 0) },
	{ "m25p64-nonjedec",  INFO(0, 0,  64 * 1024, 128, 0) },
	{ "m25p128-nonjedec", INFO(0, 0, 256 * 1024,  64, 0) },

	{ "m45pe10", INFO(0x204011,  0, 64 * 1024,    2, 0) },
	{ "m45pe80", INFO(0x204014,  0, 64 * 1024,   16, 0) },
	{ "m45pe16", INFO(0x204015,  0, 64 * 1024,   32, 0) },

	{ "m25pe20", INFO(0x208012,  0, 64 * 1024,  4,       0) },
	{ "m25pe80", INFO(0x208014,  0, 64 * 1024, 16,       0) },
	{ "m25pe16", INFO(0x208015,  0, 64 * 1024, 32, SECT_4K) },

	{ "m25px16",    INFO(0x207115,  0, 64 * 1024, 32, SECT_4K) },
	{ "m25px32",    INFO(0x207116,  0, 64 * 1024, 64, SECT_4K) },
	{ "m25px32-s0", INFO(0x207316,  0, 64 * 1024, 64, SECT_4K) },
	{ "m25px32-s1", INFO(0x206316,  0, 64 * 1024, 64, SECT_4K) },
	{ "m25px64",    INFO(0x207117,  0, 64 * 1024, 128, 0) },

	/* Winbond -- w25x "blocks" are 64K, "sectors" are 4KiB */
	{ "w25x10", INFO(0xef3011, 0, 64 * 1024,  2,  SECT_4K) },
	{ "w25x20", INFO(0xef3012, 0, 64 * 1024,  4,  SECT_4K) },
	{ "w25x40", INFO(0xef3013, 0, 64 * 1024,  8,  SECT_4K) },
	{ "w25x80", INFO(0xef3014, 0, 64 * 1024,  16, SECT_4K) },
	{ "w25x16", INFO(0xef3015, 0, 64 * 1024,  32, SECT_4K) },
	{ "w25x32", INFO(0xef3016, 0, 64 * 1024,  64, SECT_4K) },
	{ "w25q32", INFO(0xef4016, 0, 64 * 1024,  64, SECT_4K) },
	{ "w25q32dw", INFO(0xef6016, 0, 64 * 1024,  64, SECT_4K) },
	{ "w25x64", INFO(0xef3017, 0, 64 * 1024, 128, SECT_4K) },
	{ "w25q64", INFO(0xef4017, 0, 64 * 1024, 128, SECT_4K) },
	{ "w25q128", INFO(0xef4018, 0, 64 * 1024, 256, SECT_4K) },
	{ "w25q80", INFO(0xef5014, 0, 64 * 1024,  16, SECT_4K) },
	{ "w25q80bl", INFO(0xef4014, 0, 64 * 1024,  16, SECT_4K) },
	{ "w25q128", INFO(0xef4018, 0, 64 * 1024, 256, SECT_4K) },
	{ "w25q256", INFO(0xef4019, 0, 64 * 1024, 512, SECT_4K) },

	/* Catalyst / On Semiconductor -- non-JEDEC */
	{ "cat25c11", CAT25_INFO(  16, 8, 16, 1, M25P_NO_ERASE | M25P_NO_FR) },
	{ "cat25c03", CAT25_INFO(  32, 8, 16, 2, M25P_NO_ERASE | M25P_NO_FR) },
	{ "cat25c09", CAT25_INFO( 128, 8, 32, 2, M25P_NO_ERASE | M25P_NO_FR) },
	{ "cat25c17", CAT25_INFO( 256, 8, 32, 2, M25P_NO_ERASE | M25P_NO_FR) },
	{ "cat25128", CAT25_INFO(2048, 8, 64, 2, M25P_NO_ERASE | M25P_NO_FR) },
	{ },
};
MODULE_DEVICE_TABLE(spi, m25p_ids);

static const struct spi_device_id *jedec_probe(struct spi_device *spi)
{
	int			tmp;
	u8			code = OPCODE_RDID;
	u8			id[5];
	u32			jedec;
	u16                     ext_jedec;
	struct flash_info	*info;

	/* JEDEC also defines an optional "extended device information"
	 * string for after vendor-specific data, after the three bytes
	 * we use here.  Supporting some chips might require using it.
	 */
	tmp = spi_write_then_read(spi, &code, 1, id, 5);
	if (tmp < 0) {
		pr_debug("%s: error %d reading JEDEC ID\n",
				dev_name(&spi->dev), tmp);
		return ERR_PTR(tmp);
	}
	jedec = id[0];
	jedec = jedec << 8;
	jedec |= id[1];
	jedec = jedec << 8;
	jedec |= id[2];

	ext_jedec = id[3] << 8 | id[4];

	for (tmp = 0; tmp < ARRAY_SIZE(m25p_ids) - 1; tmp++) {
		info = (void *)m25p_ids[tmp].driver_data;
		if (info->jedec_id == jedec) {
			if (info->ext_id == 0 || info->ext_id == ext_jedec)
				return &m25p_ids[tmp];
		}
	}
	dev_err(&spi->dev, "unrecognized JEDEC id %06x\n", jedec);
	return ERR_PTR(-ENODEV);
}


/*
 * board specific setup should have ensured the SPI clock used here
 * matches what the READ command supports, at least until this driver
 * understands FAST_READ (for clocks over 25 MHz).
 */
static int m25p_probe(struct spi_device *spi)
{
	const struct spi_device_id	*id = spi_get_device_id(spi);
	struct flash_platform_data	*data;
	struct m25p			*flash;
	struct flash_info		*info;
	unsigned			i;
	struct mtd_part_parser_data	ppdata;
	struct device_node *np = spi->dev.of_node;
	int ret;

	/* Platform data helps sort out which chip type we have, as
	 * well as how this board partitions it.  If we don't have
	 * a chip ID, try the JEDEC id commands; they'll work for most
	 * newer chips, even if we don't recognize the particular chip.
	 */
	data = dev_get_platdata(&spi->dev);
	if (data && data->type) {
		const struct spi_device_id *plat_id;

		for (i = 0; i < ARRAY_SIZE(m25p_ids) - 1; i++) {
			plat_id = &m25p_ids[i];
			if (strcmp(data->type, plat_id->name))
				continue;
			break;
		}

		if (i < ARRAY_SIZE(m25p_ids) - 1)
			id = plat_id;
		else
			dev_warn(&spi->dev, "unrecognized id %s\n", data->type);
	}

	info = (void *)id->driver_data;

	if (info->jedec_id) {
		const struct spi_device_id *jid;

		jid = jedec_probe(spi);
		if (IS_ERR(jid)) {
			return PTR_ERR(jid);
		} else if (jid != id) {
			/*
			 * JEDEC knows better, so overwrite platform ID. We
			 * can't trust partitions any longer, but we'll let
			 * mtd apply them anyway, since some partitions may be
			 * marked read-only, and we don't want to lose that
			 * information, even if it's not 100% accurate.
			 */
			dev_warn(&spi->dev, "found %s, expected %s\n",
				 jid->name, id->name);
			id = jid;
			info = (void *)jid->driver_data;
		}
	}

	flash = devm_kzalloc(&spi->dev, sizeof(*flash), GFP_KERNEL);
	if (!flash)
		return -ENOMEM;

	flash->command = devm_kzalloc(&spi->dev, MAX_CMD_SIZE, GFP_KERNEL);
	if (!flash->command)
		return -ENOMEM;

	flash->spi = spi;
	mutex_init(&flash->lock);
	spi_set_drvdata(spi, flash);

	/*
	 * Atmel, SST and Intel/Numonyx serial flash tend to power
	 * up with the software protection bits set
	 */

	if (JEDEC_MFR(info->jedec_id) == CFI_MFR_ATMEL ||
	    JEDEC_MFR(info->jedec_id) == CFI_MFR_INTEL ||
	    JEDEC_MFR(info->jedec_id) == CFI_MFR_SST) {
		write_enable(flash);
		write_sr(flash, 0);
	}

	if (data && data->name)
		flash->mtd.name = data->name;
	else
		flash->mtd.name = dev_name(&spi->dev);

	flash->mtd.type = MTD_NORFLASH;
	flash->mtd.writesize = 1;
	flash->mtd.flags = MTD_CAP_NORFLASH;
	flash->mtd.size = info->sector_size * info->n_sectors;
	flash->mtd._erase = m25p80_erase;
	flash->mtd._read = m25p80_read;

	/* flash protection support for STmicro chips */
	if (JEDEC_MFR(info->jedec_id) == CFI_MFR_ST) {
		flash->mtd._lock = m25p80_lock;
		flash->mtd._unlock = m25p80_unlock;
	}

	/* sst flash chips use AAI word program */
	if (info->flags & SST_WRITE)
		flash->mtd._write = sst_write;
	else
		flash->mtd._write = m25p80_write;

	/* prefer "small sector" erase if possible */
	if (info->flags & SECT_4K) {
		flash->erase_opcode = OPCODE_BE_4K;
		flash->mtd.erasesize = 4096;
	} else if (info->flags & SECT_4K_PMC) {
		flash->erase_opcode = OPCODE_BE_4K_PMC;
		flash->mtd.erasesize = 4096;
	} else {
		flash->erase_opcode = OPCODE_SE;
		flash->mtd.erasesize = info->sector_size;
	}

	if (info->flags & M25P_NO_ERASE)
		flash->mtd.flags |= MTD_NO_ERASE;

	ppdata.of_node = spi->dev.of_node;
	flash->mtd.dev.parent = &spi->dev;
	flash->page_size = info->page_size;
	flash->mtd.writebufsize = flash->page_size;

	if (np) {
		/* If we were instantiated by DT, use it */
		if (of_property_read_bool(np, "m25p,fast-read"))
			flash->flash_read = M25P80_FAST;
		else
			flash->flash_read = M25P80_NORMAL;
	} else {
		/* If we weren't instantiated by DT, default to fast-read */
		flash->flash_read = M25P80_FAST;
	}

	/* Some devices cannot do fast-read, no matter what DT tells us */
	if (info->flags & M25P_NO_FR)
		flash->flash_read = M25P80_NORMAL;

	/* Quad/Dual-read mode takes precedence over fast/normal */
	if (spi->mode & SPI_RX_QUAD && info->flags & M25P80_QUAD_READ) {
		ret = set_quad_mode(flash, info->jedec_id);
		if (ret) {
			dev_err(&flash->spi->dev, "quad mode not supported\n");
			return ret;
		}
		flash->flash_read = M25P80_QUAD;
	} else if (spi->mode & SPI_RX_DUAL && info->flags & M25P80_DUAL_READ) {
		flash->flash_read = M25P80_DUAL;
	}

	/* Default commands */
	switch (flash->flash_read) {
	case M25P80_QUAD:
		flash->read_opcode = OPCODE_QUAD_READ;
		break;
	case M25P80_DUAL:
		flash->read_opcode = OPCODE_DUAL_READ;
		break;
	case M25P80_FAST:
		flash->read_opcode = OPCODE_FAST_READ;
		break;
	case M25P80_NORMAL:
		flash->read_opcode = OPCODE_NORM_READ;
		break;
	default:
		dev_err(&flash->spi->dev, "No Read opcode defined\n");
		return -EINVAL;
	}

	flash->program_opcode = OPCODE_PP;

	if (info->addr_width)
		flash->addr_width = info->addr_width;
	else if (flash->mtd.size > 0x1000000) {
		/* enable 4-byte addressing if the device exceeds 16MiB */
		flash->addr_width = 4;
		if (JEDEC_MFR(info->jedec_id) == CFI_MFR_AMD) {
			/* Dedicated 4-byte command set */
			switch (flash->flash_read) {
			case M25P80_QUAD:
				flash->read_opcode = OPCODE_QUAD_READ_4B;
				break;
			case M25P80_DUAL:
				flash->read_opcode = OPCODE_DUAL_READ_4B;
				break;
			case M25P80_FAST:
				flash->read_opcode = OPCODE_FAST_READ_4B;
				break;
			case M25P80_NORMAL:
				flash->read_opcode = OPCODE_NORM_READ_4B;
				break;
			}
			flash->program_opcode = OPCODE_PP_4B;
			/* No small sector erase for 4-byte command set */
			flash->erase_opcode = OPCODE_SE_4B;
			flash->mtd.erasesize = info->sector_size;
		} else
			set_4byte(flash, info->jedec_id, 1);
	} else {
		flash->addr_width = 3;
	}

	dev_info(&spi->dev, "%s (%lld Kbytes)\n", id->name,
			(long long)flash->mtd.size >> 10);

	pr_debug("mtd .name = %s, .size = 0x%llx (%lldMiB) "
			".erasesize = 0x%.8x (%uKiB) .numeraseregions = %d\n",
		flash->mtd.name,
		(long long)flash->mtd.size, (long long)(flash->mtd.size >> 20),
		flash->mtd.erasesize, flash->mtd.erasesize / 1024,
		flash->mtd.numeraseregions);

	if (flash->mtd.numeraseregions)
		for (i = 0; i < flash->mtd.numeraseregions; i++)
			pr_debug("mtd.eraseregions[%d] = { .offset = 0x%llx, "
				".erasesize = 0x%.8x (%uKiB), "
				".numblocks = %d }\n",
				i, (long long)flash->mtd.eraseregions[i].offset,
				flash->mtd.eraseregions[i].erasesize,
				flash->mtd.eraseregions[i].erasesize / 1024,
				flash->mtd.eraseregions[i].numblocks);


	/* partitions should match sector boundaries; and it may be good to
	 * use readonly partitions for writeprotected sectors (BP2..BP0).
	 */
	return mtd_device_parse_register(&flash->mtd, NULL, &ppdata,
			data ? data->parts : NULL,
			data ? data->nr_parts : 0);
}


static int m25p_remove(struct spi_device *spi)
{
	struct m25p	*flash = spi_get_drvdata(spi);

	/* Clean up MTD stuff. */
	return mtd_device_unregister(&flash->mtd);
}


static struct spi_driver m25p80_driver = {
	.driver = {
		.name	= "m25p80",
		.owner	= THIS_MODULE,
	},
	.id_table	= m25p_ids,
	.probe	= m25p_probe,
	.remove	= m25p_remove,

	/* REVISIT: many of these chips have deep power-down modes, which
	 * should clearly be entered on suspend() to minimize power use.
	 * And also when they're otherwise idle...
	 */
};

module_spi_driver(m25p80_driver);

MODULE_LICENSE("GPL");
MODULE_AUTHOR("Mike Lavender");
MODULE_DESCRIPTION("MTD SPI driver for ST M25Pxx flash chips");