aboutsummaryrefslogtreecommitdiffstats
path: root/drivers/mtd/devices/mtd_dataflash.c
blob: 93e3627be74c76a37117f13883e74d0bd1607f11 (plain) (blame)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
448
449
450
451
452
453
454
455
456
457
458
459
460
461
462
463
464
465
466
467
468
469
470
471
472
473
474
475
476
477
478
479
480
481
482
483
484
485
486
487
488
489
490
491
492
493
494
495
496
497
498
499
500
501
502
503
504
505
506
507
508
509
510
511
512
513
514
515
516
517
518
519
520
521
522
523
524
525
526
527
528
529
530
531
532
533
534
535
536
537
538
539
540
541
542
543
544
545
546
547
548
549
550
551
552
553
554
555
556
557
558
559
560
561
562
563
564
565
566
567
568
569
570
571
572
573
574
575
576
577
578
579
580
581
582
583
584
585
586
587
588
589
590
591
592
593
594
595
596
597
598
599
600
601
602
603
604
605
606
607
608
609
610
611
612
613
614
615
616
617
618
619
620
621
622
623
624
625
626
627
628
629
630
631
632
633
634
635
636
637
638
639
640
641
642
643
644
645
646
647
648
649
650
651
652
653
654
655
656
657
658
659
660
661
662
663
664
665
666
667
668
669
670
671
672
673
674
675
676
677
678
679
680
681
682
683
684
685
686
687
688
689
690
691
692
693
694
695
696
697
698
699
700
701
702
703
704
705
706
707
708
709
710
711
712
713
714
715
716
717
718
719
720
721
722
723
724
725
726
727
728
729
730
731
732
733
734
735
736
737
738
739
740
741
742
743
744
745
746
747
748
749
750
751
752
753
754
755
756
757
758
759
760
761
762
763
764
765
766
767
768
769
770
771
772
773
774
775
776
777
778
779
780
781
782
783
784
785
786
787
788
789
790
791
792
793
794
795
796
797
798
799
800
801
802
803
804
805
806
807
808
809
810
811
812
813
814
815
816
817
818
819
820
821
822
823
824
825
826
827
828
829
830
831
832
833
834
835
836
837
838
839
840
841
842
843
844
845
846
847
848
849
850
851
852
853
854
855
856
857
858
859
860
861
862
863
864
865
866
867
868
869
870
871
872
873
874
875
876
877
878
879
880
881
882
883
884
885
886
887
888
889
890
891
892
893
894
895
896
897
898
899
900
901
902
903
904
905
906
907
908
909
910
911
912
913
914
915
916
917
918
919
920
921
922
923
924
925
926
927
928
929
930
931
932
933
934
935
936
937
938
939
940
941
942
943
944
945
946
947
948
949
950
951
952
953
954
955
956
957
958
959
960
961
962
963
964
965
966
967
968
969
/*
 * Atmel AT45xxx DataFlash MTD driver for lightweight SPI framework
 *
 * Largely derived from at91_dataflash.c:
 *  Copyright (C) 2003-2005 SAN People (Pty) Ltd
 *
 * This program is free software; you can redistribute it and/or
 * modify it under the terms of the GNU General Public License
 * as published by the Free Software Foundation; either version
 * 2 of the License, or (at your option) any later version.
*/
#include <linux/module.h>
#include <linux/init.h>
#include <linux/slab.h>
#include <linux/delay.h>
#include <linux/device.h>
#include <linux/mutex.h>
#include <linux/err.h>
#include <linux/math64.h>

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

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


/*
 * DataFlash is a kind of SPI flash.  Most AT45 chips have two buffers in
 * each chip, which may be used for double buffered I/O; but this driver
 * doesn't (yet) use these for any kind of i/o overlap or prefetching.
 *
 * Sometimes DataFlash is packaged in MMC-format cards, although the
 * MMC stack can't (yet?) distinguish between MMC and DataFlash
 * protocols during enumeration.
 */

/* reads can bypass the buffers */
#define OP_READ_CONTINUOUS	0xE8
#define OP_READ_PAGE		0xD2

/* group B requests can run even while status reports "busy" */
#define OP_READ_STATUS		0xD7	/* group B */

/* move data between host and buffer */
#define OP_READ_BUFFER1		0xD4	/* group B */
#define OP_READ_BUFFER2		0xD6	/* group B */
#define OP_WRITE_BUFFER1	0x84	/* group B */
#define OP_WRITE_BUFFER2	0x87	/* group B */

/* erasing flash */
#define OP_ERASE_PAGE		0x81
#define OP_ERASE_BLOCK		0x50

/* move data between buffer and flash */
#define OP_TRANSFER_BUF1	0x53
#define OP_TRANSFER_BUF2	0x55
#define OP_MREAD_BUFFER1	0xD4
#define OP_MREAD_BUFFER2	0xD6
#define OP_MWERASE_BUFFER1	0x83
#define OP_MWERASE_BUFFER2	0x86
#define OP_MWRITE_BUFFER1	0x88	/* sector must be pre-erased */
#define OP_MWRITE_BUFFER2	0x89	/* sector must be pre-erased */

/* write to buffer, then write-erase to flash */
#define OP_PROGRAM_VIA_BUF1	0x82
#define OP_PROGRAM_VIA_BUF2	0x85

/* compare buffer to flash */
#define OP_COMPARE_BUF1		0x60
#define OP_COMPARE_BUF2		0x61

/* read flash to buffer, then write-erase to flash */
#define OP_REWRITE_VIA_BUF1	0x58
#define OP_REWRITE_VIA_BUF2	0x59

/* newer chips report JEDEC manufacturer and device IDs; chip
 * serial number and OTP bits; and per-sector writeprotect.
 */
#define OP_READ_ID		0x9F
#define OP_READ_SECURITY	0x77
#define OP_WRITE_SECURITY_REVC	0x9A
#define OP_WRITE_SECURITY	0x9B	/* revision D */


struct dataflash {
	uint8_t			command[4];
	char			name[24];

	unsigned		partitioned:1;

	unsigned short		page_offset;	/* offset in flash address */
	unsigned int		page_size;	/* of bytes per page */

	struct mutex		lock;
	struct spi_device	*spi;

	struct mtd_info		mtd;
};

/* ......................................................................... */

/*
 * Return the status of the DataFlash device.
 */
static inline int dataflash_status(struct spi_device *spi)
{
	/* NOTE:  at45db321c over 25 MHz wants to write
	 * a dummy byte after the opcode...
	 */
	return spi_w8r8(spi, OP_READ_STATUS);
}

/*
 * Poll the DataFlash device until it is READY.
 * This usually takes 5-20 msec or so; more for sector erase.
 */
static int dataflash_waitready(struct spi_device *spi)
{
	int	status;

	for (;;) {
		status = dataflash_status(spi);
		if (status < 0) {
			DEBUG(MTD_DEBUG_LEVEL1, "%s: status %d?\n",
					dev_name(&spi->dev), status);
			status = 0;
		}

		if (status & (1 << 7))	/* RDY/nBSY */
			return status;

		msleep(3);
	}
}

/* ......................................................................... */

/*
 * Erase pages of flash.
 */
static int dataflash_erase(struct mtd_info *mtd, struct erase_info *instr)
{
	struct dataflash	*priv = (struct dataflash *)mtd->priv;
	struct spi_device	*spi = priv->spi;
	struct spi_transfer	x = { .tx_dma = 0, };
	struct spi_message	msg;
	unsigned		blocksize = priv->page_size << 3;
	uint8_t			*command;
	uint32_t		rem;

	DEBUG(MTD_DEBUG_LEVEL2, "%s: erase addr=0x%llx len 0x%llx\n",
	      dev_name(&spi->dev), (long long)instr->addr,
	      (long long)instr->len);

	/* Sanity checks */
	if (instr->addr + instr->len > mtd->size)
		return -EINVAL;
	div_u64_rem(instr->len, priv->page_size, &rem);
	if (rem)
		return -EINVAL;
	div_u64_rem(instr->addr, priv->page_size, &rem);
	if (rem)
		return -EINVAL;

	spi_message_init(&msg);

	x.tx_buf = command = priv->command;
	x.len = 4;
	spi_message_add_tail(&x, &msg);

	mutex_lock(&priv->lock);
	while (instr->len > 0) {
		unsigned int	pageaddr;
		int		status;
		int		do_block;

		/* Calculate flash page address; use block erase (for speed) if
		 * we're at a block boundary and need to erase the whole block.
		 */
		pageaddr = div_u64(instr->addr, priv->page_size);
		do_block = (pageaddr & 0x7) == 0 && instr->len >= blocksize;
		pageaddr = pageaddr << priv->page_offset;

		command[0] = do_block ? OP_ERASE_BLOCK : OP_ERASE_PAGE;
		command[1] = (uint8_t)(pageaddr >> 16);
		command[2] = (uint8_t)(pageaddr >> 8);
		command[3] = 0;

		DEBUG(MTD_DEBUG_LEVEL3, "ERASE %s: (%x) %x %x %x [%i]\n",
			do_block ? "block" : "page",
			command[0], command[1], command[2], command[3],
			pageaddr);

		status = spi_sync(spi, &msg);
		(void) dataflash_waitready(spi);

		if (status < 0) {
			printk(KERN_ERR "%s: erase %x, err %d\n",
				dev_name(&spi->dev), pageaddr, status);
			/* REVISIT:  can retry instr->retries times; or
			 * giveup and instr->fail_addr = instr->addr;
			 */
			continue;
		}

		if (do_block) {
			instr->addr += blocksize;
			instr->len -= blocksize;
		} else {
			instr->addr += priv->page_size;
			instr->len -= priv->page_size;
		}
	}
	mutex_unlock(&priv->lock);

	/* Inform MTD subsystem that erase is complete */
	instr->state = MTD_ERASE_DONE;
	mtd_erase_callback(instr);

	return 0;
}

/*
 * Read from the DataFlash device.
 *   from   : Start offset in flash device
 *   len    : Amount to read
 *   retlen : About of data actually read
 *   buf    : Buffer containing the data
 */
static int dataflash_read(struct mtd_info *mtd, loff_t from, size_t len,
			       size_t *retlen, u_char *buf)
{
	struct dataflash	*priv = (struct dataflash *)mtd->priv;
	struct spi_transfer	x[2] = { { .tx_dma = 0, }, };
	struct spi_message	msg;
	unsigned int		addr;
	uint8_t			*command;
	int			status;

	DEBUG(MTD_DEBUG_LEVEL2, "%s: read 0x%x..0x%x\n",
		dev_name(&priv->spi->dev), (unsigned)from, (unsigned)(from + len));

	*retlen = 0;

	/* Sanity checks */
	if (!len)
		return 0;
	if (from + len > mtd->size)
		return -EINVAL;

	/* Calculate flash page/byte address */
	addr = (((unsigned)from / priv->page_size) << priv->page_offset)
		+ ((unsigned)from % priv->page_size);

	command = priv->command;

	DEBUG(MTD_DEBUG_LEVEL3, "READ: (%x) %x %x %x\n",
		command[0], command[1], command[2], command[3]);

	spi_message_init(&msg);

	x[0].tx_buf = command;
	x[0].len = 8;
	spi_message_add_tail(&x[0], &msg);

	x[1].rx_buf = buf;
	x[1].len = len;
	spi_message_add_tail(&x[1], &msg);

	mutex_lock(&priv->lock);

	/* Continuous read, max clock = f(car) which may be less than
	 * the peak rate available.  Some chips support commands with
	 * fewer "don't care" bytes.  Both buffers stay unchanged.
	 */
	command[0] = OP_READ_CONTINUOUS;
	command[1] = (uint8_t)(addr >> 16);
	command[2] = (uint8_t)(addr >> 8);
	command[3] = (uint8_t)(addr >> 0);
	/* plus 4 "don't care" bytes */

	status = spi_sync(priv->spi, &msg);
	mutex_unlock(&priv->lock);

	if (status >= 0) {
		*retlen = msg.actual_length - 8;
		status = 0;
	} else
		DEBUG(MTD_DEBUG_LEVEL1, "%s: read %x..%x --> %d\n",
			dev_name(&priv->spi->dev),
			(unsigned)from, (unsigned)(from + len),
			status);
	return status;
}

/*
 * Write to the DataFlash device.
 *   to     : Start offset in flash device
 *   len    : Amount to write
 *   retlen : Amount of data actually written
 *   buf    : Buffer containing the data
 */
static int dataflash_write(struct mtd_info *mtd, loff_t to, size_t len,
				size_t * retlen, const u_char * buf)
{
	struct dataflash	*priv = (struct dataflash *)mtd->priv;
	struct spi_device	*spi = priv->spi;
	struct spi_transfer	x[2] = { { .tx_dma = 0, }, };
	struct spi_message	msg;
	unsigned int		pageaddr, addr, offset, writelen;
	size_t			remaining = len;
	u_char			*writebuf = (u_char *) buf;
	int			status = -EINVAL;
	uint8_t			*command;

	DEBUG(MTD_DEBUG_LEVEL2, "%s: write 0x%x..0x%x\n",
		dev_name(&spi->dev), (unsigned)to, (unsigned)(to + len));

	*retlen = 0;

	/* Sanity checks */
	if (!len)
		return 0;
	if ((to + len) > mtd->size)
		return -EINVAL;

	spi_message_init(&msg);

	x[0].tx_buf = command = priv->command;
	x[0].len = 4;
	spi_message_add_tail(&x[0], &msg);

	pageaddr = ((unsigned)to / priv->page_size);
	offset = ((unsigned)to % priv->page_size);
	if (offset + len > priv->page_size)
		writelen = priv->page_size - offset;
	else
		writelen = len;

	mutex_lock(&priv->lock);
	while (remaining > 0) {
		DEBUG(MTD_DEBUG_LEVEL3, "write @ %i:%i len=%i\n",
			pageaddr, offset, writelen);

		/* REVISIT:
		 * (a) each page in a sector must be rewritten at least
		 *     once every 10K sibling erase/program operations.
		 * (b) for pages that are already erased, we could
		 *     use WRITE+MWRITE not PROGRAM for ~30% speedup.
		 * (c) WRITE to buffer could be done while waiting for
		 *     a previous MWRITE/MWERASE to complete ...
		 * (d) error handling here seems to be mostly missing.
		 *
		 * Two persistent bits per page, plus a per-sector counter,
		 * could support (a) and (b) ... we might consider using
		 * the second half of sector zero, which is just one block,
		 * to track that state.  (On AT91, that sector should also
		 * support boot-from-DataFlash.)
		 */

		addr = pageaddr << priv->page_offset;

		/* (1) Maybe transfer partial page to Buffer1 */
		if (writelen != priv->page_size) {
			command[0] = OP_TRANSFER_BUF1;
			command[1] = (addr & 0x00FF0000) >> 16;
			command[2] = (addr & 0x0000FF00) >> 8;
			command[3] = 0;

			DEBUG(MTD_DEBUG_LEVEL3, "TRANSFER: (%x) %x %x %x\n",
				command[0], command[1], command[2], command[3]);

			status = spi_sync(spi, &msg);
			if (status < 0)
				DEBUG(MTD_DEBUG_LEVEL1, "%s: xfer %u -> %d \n",
					dev_name(&spi->dev), addr, status);

			(void) dataflash_waitready(priv->spi);
		}

		/* (2) Program full page via Buffer1 */
		addr += offset;
		command[0] = OP_PROGRAM_VIA_BUF1;
		command[1] = (addr & 0x00FF0000) >> 16;
		command[2] = (addr & 0x0000FF00) >> 8;
		command[3] = (addr & 0x000000FF);

		DEBUG(MTD_DEBUG_LEVEL3, "PROGRAM: (%x) %x %x %x\n",
			command[0], command[1], command[2], command[3]);

		x[1].tx_buf = writebuf;
		x[1].len = writelen;
		spi_message_add_tail(x + 1, &msg);
		status = spi_sync(spi, &msg);
		spi_transfer_del(x + 1);
		if (status < 0)
			DEBUG(MTD_DEBUG_LEVEL1, "%s: pgm %u/%u -> %d \n",
				dev_name(&spi->dev), addr, writelen, status);

		(void) dataflash_waitready(priv->spi);


#ifdef CONFIG_MTD_DATAFLASH_WRITE_VERIFY

		/* (3) Compare to Buffer1 */
		addr = pageaddr << priv->page_offset;
		command[0] = OP_COMPARE_BUF1;
		command[1] = (addr & 0x00FF0000) >> 16;
		command[2] = (addr & 0x0000FF00) >> 8;
		command[3] = 0;

		DEBUG(MTD_DEBUG_LEVEL3, "COMPARE: (%x) %x %x %x\n",
			command[0], command[1], command[2], command[3]);

		status = spi_sync(spi, &msg);
		if (status < 0)
			DEBUG(MTD_DEBUG_LEVEL1, "%s: compare %u -> %d \n",
				dev_name(&spi->dev), addr, status);

		status = dataflash_waitready(priv->spi);

		/* Check result of the compare operation */
		if (status & (1 << 6)) {
			printk(KERN_ERR "%s: compare page %u, err %d\n",
				dev_name(&spi->dev), pageaddr, status);
			remaining = 0;
			status = -EIO;
			break;
		} else
			status = 0;

#endif	/* CONFIG_MTD_DATAFLASH_WRITE_VERIFY */

		remaining = remaining - writelen;
		pageaddr++;
		offset = 0;
		writebuf += writelen;
		*retlen += writelen;

		if (remaining > priv->page_size)
			writelen = priv->page_size;
		else
			writelen = remaining;
	}
	mutex_unlock(&priv->lock);

	return status;
}

/* ......................................................................... */

#ifdef CONFIG_MTD_DATAFLASH_OTP

static int dataflash_get_otp_info(struct mtd_info *mtd,
		struct otp_info *info, size_t len)
{
	/* Report both blocks as identical:  bytes 0..64, locked.
	 * Unless the user block changed from all-ones, we can't
	 * tell whether it's still writable; so we assume it isn't.
	 */
	info->start = 0;
	info->length = 64;
	info->locked = 1;
	return sizeof(*info);
}

static ssize_t otp_read(struct spi_device *spi, unsigned base,
		uint8_t *buf, loff_t off, size_t len)
{
	struct spi_message	m;
	size_t			l;
	uint8_t			*scratch;
	struct spi_transfer	t;
	int			status;

	if (off > 64)
		return -EINVAL;

	if ((off + len) > 64)
		len = 64 - off;
	if (len == 0)
		return len;

	spi_message_init(&m);

	l = 4 + base + off + len;
	scratch = kzalloc(l, GFP_KERNEL);
	if (!scratch)
		return -ENOMEM;

	/* OUT: OP_READ_SECURITY, 3 don't-care bytes, zeroes
	 * IN:  ignore 4 bytes, data bytes 0..N (max 127)
	 */
	scratch[0] = OP_READ_SECURITY;

	memset(&t, 0, sizeof t);
	t.tx_buf = scratch;
	t.rx_buf = scratch;
	t.len = l;
	spi_message_add_tail(&t, &m);

	dataflash_waitready(spi);

	status = spi_sync(spi, &m);
	if (status >= 0) {
		memcpy(buf, scratch + 4 + base + off, len);
		status = len;
	}

	kfree(scratch);
	return status;
}

static int dataflash_read_fact_otp(struct mtd_info *mtd,
		loff_t from, size_t len, size_t *retlen, u_char *buf)
{
	struct dataflash	*priv = (struct dataflash *)mtd->priv;
	int			status;

	/* 64 bytes, from 0..63 ... start at 64 on-chip */
	mutex_lock(&priv->lock);
	status = otp_read(priv->spi, 64, buf, from, len);
	mutex_unlock(&priv->lock);

	if (status < 0)
		return status;
	*retlen = status;
	return 0;
}

static int dataflash_read_user_otp(struct mtd_info *mtd,
		loff_t from, size_t len, size_t *retlen, u_char *buf)
{
	struct dataflash	*priv = (struct dataflash *)mtd->priv;
	int			status;

	/* 64 bytes, from 0..63 ... start at 0 on-chip */
	mutex_lock(&priv->lock);
	status = otp_read(priv->spi, 0, buf, from, len);
	mutex_unlock(&priv->lock);

	if (status < 0)
		return status;
	*retlen = status;
	return 0;
}

static int dataflash_write_user_otp(struct mtd_info *mtd,
		loff_t from, size_t len, size_t *retlen, u_char *buf)
{
	struct spi_message	m;
	const size_t		l = 4 + 64;
	uint8_t			*scratch;
	struct spi_transfer	t;
	struct dataflash	*priv = (struct dataflash *)mtd->priv;
	int			status;

	if (len > 64)
		return -EINVAL;

	/* Strictly speaking, we *could* truncate the write ... but
	 * let's not do that for the only write that's ever possible.
	 */
	if ((from + len) > 64)
		return -EINVAL;

	/* OUT: OP_WRITE_SECURITY, 3 zeroes, 64 data-or-zero bytes
	 * IN:  ignore all
	 */
	scratch = kzalloc(l, GFP_KERNEL);
	if (!scratch)
		return -ENOMEM;
	scratch[0] = OP_WRITE_SECURITY;
	memcpy(scratch + 4 + from, buf, len);

	spi_message_init(&m);

	memset(&t, 0, sizeof t);
	t.tx_buf = scratch;
	t.len = l;
	spi_message_add_tail(&t, &m);

	/* Write the OTP bits, if they've not yet been written.
	 * This modifies SRAM buffer1.
	 */
	mutex_lock(&priv->lock);
	dataflash_waitready(priv->spi);
	status = spi_sync(priv->spi, &m);
	mutex_unlock(&priv->lock);

	kfree(scratch);

	if (status >= 0) {
		status = 0;
		*retlen = len;
	}
	return status;
}

static char *otp_setup(struct mtd_info *device, char revision)
{
	device->get_fact_prot_info = dataflash_get_otp_info;
	device->read_fact_prot_reg = dataflash_read_fact_otp;
	device->get_user_prot_info = dataflash_get_otp_info;
	device->read_user_prot_reg = dataflash_read_user_otp;

	/* rev c parts (at45db321c and at45db1281 only!) use a
	 * different write procedure; not (yet?) implemented.
	 */
	if (revision > 'c')
		device->write_user_prot_reg = dataflash_write_user_otp;

	return ", OTP";
}

#else

static char *otp_setup(struct mtd_info *device, char revision)
{
	return " (OTP)";
}

#endif

/* ......................................................................... */

/*
 * Register DataFlash device with MTD subsystem.
 */
static int __devinit
add_dataflash_otp(struct spi_device *spi, char *name,
		int nr_pages, int pagesize, int pageoffset, char revision)
{
	struct dataflash		*priv;
	struct mtd_info			*device;
	struct flash_platform_data	*pdata = spi->dev.platform_data;
	char				*otp_tag = "";

	priv = kzalloc(sizeof *priv, GFP_KERNEL);
	if (!priv)
		return -ENOMEM;

	mutex_init(&priv->lock);
	priv->spi = spi;
	priv->page_size = pagesize;
	priv->page_offset = pageoffset;

	/* name must be usable with cmdlinepart */
	sprintf(priv->name, "spi%d.%d-%s",
			spi->master->bus_num, spi->chip_select,
			name);

	device = &priv->mtd;
	device->name = (pdata && pdata->name) ? pdata->name : priv->name;
	device->size = nr_pages * pagesize;
	device->erasesize = pagesize;
	device->writesize = pagesize;
	device->owner = THIS_MODULE;
	device->type = MTD_DATAFLASH;
	device->flags = MTD_WRITEABLE;
	device->erase = dataflash_erase;
	device->read = dataflash_read;
	device->write = dataflash_write;
	device->priv = priv;

	device->dev.parent = &spi->dev;

	if (revision >= 'c')
		otp_tag = otp_setup(device, revision);

	dev_info(&spi->dev, "%s (%lld KBytes) pagesize %d bytes%s\n",
			name, (long long)((device->size + 1023) >> 10),
			pagesize, otp_tag);
	dev_set_drvdata(&spi->dev, priv);

	if (mtd_has_partitions()) {
		struct mtd_partition	*parts;
		int			nr_parts = 0;

		if (mtd_has_cmdlinepart()) {
			static const char *part_probes[]
					= { "cmdlinepart", NULL, };

			nr_parts = parse_mtd_partitions(device,
					part_probes, &parts, 0);
		}

		if (nr_parts <= 0 && pdata && pdata->parts) {
			parts = pdata->parts;
			nr_parts = pdata->nr_parts;
		}

		if (nr_parts > 0) {
			priv->partitioned = 1;
			return add_mtd_partitions(device, parts, nr_parts);
		}
	} else if (pdata && pdata->nr_parts)
		dev_warn(&spi->dev, "ignoring %d default partitions on %s\n",
				pdata->nr_parts, device->name);

	return add_mtd_device(device) == 1 ? -ENODEV : 0;
}

static inline int __devinit
add_dataflash(struct spi_device *spi, char *name,
		int nr_pages, int pagesize, int pageoffset)
{
	return add_dataflash_otp(spi, name, nr_pages, pagesize,
			pageoffset, 0);
}

struct flash_info {
	char		*name;

	/* JEDEC id has a high byte of zero plus three data bytes:
	 * the manufacturer id, then a two byte device id.
	 */
	uint32_t	jedec_id;

	/* The size listed here is what works with OP_ERASE_PAGE. */
	unsigned	nr_pages;
	uint16_t	pagesize;
	uint16_t	pageoffset;

	uint16_t	flags;
#define SUP_POW2PS	0x0002		/* supports 2^N byte pages */
#define IS_POW2PS	0x0001		/* uses 2^N byte pages */
};

static struct flash_info __devinitdata dataflash_data [] = {

	/*
	 * NOTE:  chips with SUP_POW2PS (rev D and up) need two entries,
	 * one with IS_POW2PS and the other without.  The entry with the
	 * non-2^N byte page size can't name exact chip revisions without
	 * losing backwards compatibility for cmdlinepart.
	 *
	 * These newer chips also support 128-byte security registers (with
	 * 64 bytes one-time-programmable) and software write-protection.
	 */
	{ "AT45DB011B",  0x1f2200, 512, 264, 9, SUP_POW2PS},
	{ "at45db011d",  0x1f2200, 512, 256, 8, SUP_POW2PS | IS_POW2PS},

	{ "AT45DB021B",  0x1f2300, 1024, 264, 9, SUP_POW2PS},
	{ "at45db021d",  0x1f2300, 1024, 256, 8, SUP_POW2PS | IS_POW2PS},

	{ "AT45DB041x",  0x1f2400, 2048, 264, 9, SUP_POW2PS},
	{ "at45db041d",  0x1f2400, 2048, 256, 8, SUP_POW2PS | IS_POW2PS},

	{ "AT45DB081B",  0x1f2500, 4096, 264, 9, SUP_POW2PS},
	{ "at45db081d",  0x1f2500, 4096, 256, 8, SUP_POW2PS | IS_POW2PS},

	{ "AT45DB161x",  0x1f2600, 4096, 528, 10, SUP_POW2PS},
	{ "at45db161d",  0x1f2600, 4096, 512, 9, SUP_POW2PS | IS_POW2PS},

	{ "AT45DB321x",  0x1f2700, 8192, 528, 10, 0},		/* rev C */

	{ "AT45DB321x",  0x1f2701, 8192, 528, 10, SUP_POW2PS},
	{ "at45db321d",  0x1f2701, 8192, 512, 9, SUP_POW2PS | IS_POW2PS},

	{ "AT45DB642x",  0x1f2800, 8192, 1056, 11, SUP_POW2PS},
	{ "at45db642d",  0x1f2800, 8192, 1024, 10, SUP_POW2PS | IS_POW2PS},
};

static struct flash_info *__devinit jedec_probe(struct spi_device *spi)
{
	int			tmp;
	uint8_t			code = OP_READ_ID;
	uint8_t			id[3];
	uint32_t		jedec;
	struct flash_info	*info;
	int status;

	/* 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.
	 *
	 * If the vendor ID isn't Atmel's (0x1f), assume this call failed.
	 * That's not an error; only rev C and newer chips handle it, and
	 * only Atmel sells these chips.
	 */
	tmp = spi_write_then_read(spi, &code, 1, id, 3);
	if (tmp < 0) {
		DEBUG(MTD_DEBUG_LEVEL0, "%s: error %d reading JEDEC ID\n",
			dev_name(&spi->dev), tmp);
		return ERR_PTR(tmp);
	}
	if (id[0] != 0x1f)
		return NULL;

	jedec = id[0];
	jedec = jedec << 8;
	jedec |= id[1];
	jedec = jedec << 8;
	jedec |= id[2];

	for (tmp = 0, info = dataflash_data;
			tmp < ARRAY_SIZE(dataflash_data);
			tmp++, info++) {
		if (info->jedec_id == jedec) {
			DEBUG(MTD_DEBUG_LEVEL1, "%s: OTP, sector protect%s\n",
				dev_name(&spi->dev),
				(info->flags & SUP_POW2PS)
					? ", binary pagesize" : ""
				);
			if (info->flags & SUP_POW2PS) {
				status = dataflash_status(spi);
				if (status < 0) {
					DEBUG(MTD_DEBUG_LEVEL1,
						"%s: status error %d\n",
						dev_name(&spi->dev), status);
					return ERR_PTR(status);
				}
				if (status & 0x1) {
					if (info->flags & IS_POW2PS)
						return info;
				} else {
					if (!(info->flags & IS_POW2PS))
						return info;
				}
			} else
				return info;
		}
	}

	/*
	 * Treat other chips as errors ... we won't know the right page
	 * size (it might be binary) even when we can tell which density
	 * class is involved (legacy chip id scheme).
	 */
	dev_warn(&spi->dev, "JEDEC id %06x not handled\n", jedec);
	return ERR_PTR(-ENODEV);
}

/*
 * Detect and initialize DataFlash device, using JEDEC IDs on newer chips
 * or else the ID code embedded in the status bits:
 *
 *   Device      Density         ID code          #Pages PageSize  Offset
 *   AT45DB011B  1Mbit   (128K)  xx0011xx (0x0c)    512    264      9
 *   AT45DB021B  2Mbit   (256K)  xx0101xx (0x14)   1024    264      9
 *   AT45DB041B  4Mbit   (512K)  xx0111xx (0x1c)   2048    264      9
 *   AT45DB081B  8Mbit   (1M)    xx1001xx (0x24)   4096    264      9
 *   AT45DB0161B 16Mbit  (2M)    xx1011xx (0x2c)   4096    528     10
 *   AT45DB0321B 32Mbit  (4M)    xx1101xx (0x34)   8192    528     10
 *   AT45DB0642  64Mbit  (8M)    xx111xxx (0x3c)   8192   1056     11
 *   AT45DB1282  128Mbit (16M)   xx0100xx (0x10)  16384   1056     11
 */
static int __devinit dataflash_probe(struct spi_device *spi)
{
	int status;
	struct flash_info	*info;

	/*
	 * Try to detect dataflash by JEDEC ID.
	 * If it succeeds we know we have either a C or D part.
	 * D will support power of 2 pagesize option.
	 * Both support the security register, though with different
	 * write procedures.
	 */
	info = jedec_probe(spi);
	if (IS_ERR(info))
		return PTR_ERR(info);
	if (info != NULL)
		return add_dataflash_otp(spi, info->name, info->nr_pages,
				info->pagesize, info->pageoffset,
				(info->flags & SUP_POW2PS) ? 'd' : 'c');

	/*
	 * Older chips support only legacy commands, identifing
	 * capacity using bits in the status byte.
	 */
	status = dataflash_status(spi);
	if (status <= 0 || status == 0xff) {
		DEBUG(MTD_DEBUG_LEVEL1, "%s: status error %d\n",
				dev_name(&spi->dev), status);
		if (status == 0 || status == 0xff)
			status = -ENODEV;
		return status;
	}

	/* if there's a device there, assume it's dataflash.
	 * board setup should have set spi->max_speed_max to
	 * match f(car) for continuous reads, mode 0 or 3.
	 */
	switch (status & 0x3c) {
	case 0x0c:	/* 0 0 1 1 x x */
		status = add_dataflash(spi, "AT45DB011B", 512, 264, 9);
		break;
	case 0x14:	/* 0 1 0 1 x x */
		status = add_dataflash(spi, "AT45DB021B", 1024, 264, 9);
		break;
	case 0x1c:	/* 0 1 1 1 x x */
		status = add_dataflash(spi, "AT45DB041x", 2048, 264, 9);
		break;
	case 0x24:	/* 1 0 0 1 x x */
		status = add_dataflash(spi, "AT45DB081B", 4096, 264, 9);
		break;
	case 0x2c:	/* 1 0 1 1 x x */
		status = add_dataflash(spi, "AT45DB161x", 4096, 528, 10);
		break;
	case 0x34:	/* 1 1 0 1 x x */
		status = add_dataflash(spi, "AT45DB321x", 8192, 528, 10);
		break;
	case 0x38:	/* 1 1 1 x x x */
	case 0x3c:
		status = add_dataflash(spi, "AT45DB642x", 8192, 1056, 11);
		break;
	/* obsolete AT45DB1282 not (yet?) supported */
	default:
		DEBUG(MTD_DEBUG_LEVEL1, "%s: unsupported device (%x)\n",
				dev_name(&spi->dev), status & 0x3c);
		status = -ENODEV;
	}

	if (status < 0)
		DEBUG(MTD_DEBUG_LEVEL1, "%s: add_dataflash --> %d\n",
				dev_name(&spi->dev), status);

	return status;
}

static int __devexit dataflash_remove(struct spi_device *spi)
{
	struct dataflash	*flash = dev_get_drvdata(&spi->dev);
	int			status;

	DEBUG(MTD_DEBUG_LEVEL1, "%s: remove\n", dev_name(&spi->dev));

	if (mtd_has_partitions() && flash->partitioned)
		status = del_mtd_partitions(&flash->mtd);
	else
		status = del_mtd_device(&flash->mtd);
	if (status == 0)
		kfree(flash);
	return status;
}

static struct spi_driver dataflash_driver = {
	.driver = {
		.name		= "mtd_dataflash",
		.bus		= &spi_bus_type,
		.owner		= THIS_MODULE,
	},

	.probe		= dataflash_probe,
	.remove		= __devexit_p(dataflash_remove),

	/* FIXME:  investigate suspend and resume... */
};

static int __init dataflash_init(void)
{
	return spi_register_driver(&dataflash_driver);
}
module_init(dataflash_init);

static void __exit dataflash_exit(void)
{
	spi_unregister_driver(&dataflash_driver);
}
module_exit(dataflash_exit);


MODULE_LICENSE("GPL");
MODULE_AUTHOR("Andrew Victor, David Brownell");
MODULE_DESCRIPTION("MTD DataFlash driver");
MODULE_ALIAS("spi:mtd_dataflash");