aboutsummaryrefslogtreecommitdiffstats
path: root/drivers/mtd/ubi/build.c
blob: 555d594d1811d7f4bb29ddd9ac329ffff85de6af (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
/*
 * Copyright (c) International Business Machines Corp., 2006
 * Copyright (c) Nokia Corporation, 2007
 *
 * 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.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See
 * the GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program; if not, write to the Free Software
 * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
 *
 * Author: Artem Bityutskiy (Битюцкий Артём),
 *         Frank Haverkamp
 */

/*
 * This file includes UBI initialization and building of UBI devices. At the
 * moment UBI devices may only be added while UBI is initialized, but dynamic
 * device add/remove functionality is planned. Also, at the moment we only
 * attach UBI devices by scanning, which will become a bottleneck when flashes
 * reach certain large size. Then one may improve UBI and add other methods.
 */

#include <linux/err.h>
#include <linux/module.h>
#include <linux/moduleparam.h>
#include <linux/stringify.h>
#include <linux/stat.h>
#include "ubi.h"

/* Maximum length of the 'mtd=' parameter */
#define MTD_PARAM_LEN_MAX 64

/**
 * struct mtd_dev_param - MTD device parameter description data structure.
 * @name: MTD device name or number string
 * @vid_hdr_offs: VID header offset
 * @data_offs: data offset
 */
struct mtd_dev_param
{
	char name[MTD_PARAM_LEN_MAX];
	int vid_hdr_offs;
	int data_offs;
};

/* Numbers of elements set in the @mtd_dev_param array */
static int mtd_devs = 0;

/* MTD devices specification parameters */
static struct mtd_dev_param mtd_dev_param[UBI_MAX_DEVICES];

/* Number of UBI devices in system */
int ubi_devices_cnt;

/* All UBI devices in system */
struct ubi_device *ubi_devices[UBI_MAX_DEVICES];

/* Root UBI "class" object (corresponds to '/<sysfs>/class/ubi/') */
struct class *ubi_class;

/* "Show" method for files in '/<sysfs>/class/ubi/' */
static ssize_t ubi_version_show(struct class *class, char *buf)
{
	return sprintf(buf, "%d\n", UBI_VERSION);
}

/* UBI version attribute ('/<sysfs>/class/ubi/version') */
static struct class_attribute ubi_version =
	__ATTR(version, S_IRUGO, ubi_version_show, NULL);

static ssize_t dev_attribute_show(struct device *dev,
				  struct device_attribute *attr, char *buf);

/* UBI device attributes (correspond to files in '/<sysfs>/class/ubi/ubiX') */
static struct device_attribute dev_eraseblock_size =
	__ATTR(eraseblock_size, S_IRUGO, dev_attribute_show, NULL);
static struct device_attribute dev_avail_eraseblocks =
	__ATTR(avail_eraseblocks, S_IRUGO, dev_attribute_show, NULL);
static struct device_attribute dev_total_eraseblocks =
	__ATTR(total_eraseblocks, S_IRUGO, dev_attribute_show, NULL);
static struct device_attribute dev_volumes_count =
	__ATTR(volumes_count, S_IRUGO, dev_attribute_show, NULL);
static struct device_attribute dev_max_ec =
	__ATTR(max_ec, S_IRUGO, dev_attribute_show, NULL);
static struct device_attribute dev_reserved_for_bad =
	__ATTR(reserved_for_bad, S_IRUGO, dev_attribute_show, NULL);
static struct device_attribute dev_bad_peb_count =
	__ATTR(bad_peb_count, S_IRUGO, dev_attribute_show, NULL);
static struct device_attribute dev_max_vol_count =
	__ATTR(max_vol_count, S_IRUGO, dev_attribute_show, NULL);
static struct device_attribute dev_min_io_size =
	__ATTR(min_io_size, S_IRUGO, dev_attribute_show, NULL);
static struct device_attribute dev_bgt_enabled =
	__ATTR(bgt_enabled, S_IRUGO, dev_attribute_show, NULL);

/* "Show" method for files in '/<sysfs>/class/ubi/ubiX/' */
static ssize_t dev_attribute_show(struct device *dev,
				  struct device_attribute *attr, char *buf)
{
	const struct ubi_device *ubi;

	ubi = container_of(dev, struct ubi_device, dev);
	if (attr == &dev_eraseblock_size)
		return sprintf(buf, "%d\n", ubi->leb_size);
	else if (attr == &dev_avail_eraseblocks)
		return sprintf(buf, "%d\n", ubi->avail_pebs);
	else if (attr == &dev_total_eraseblocks)
		return sprintf(buf, "%d\n", ubi->good_peb_count);
	else if (attr == &dev_volumes_count)
		return sprintf(buf, "%d\n", ubi->vol_count);
	else if (attr == &dev_max_ec)
		return sprintf(buf, "%d\n", ubi->max_ec);
	else if (attr == &dev_reserved_for_bad)
		return sprintf(buf, "%d\n", ubi->beb_rsvd_pebs);
	else if (attr == &dev_bad_peb_count)
		return sprintf(buf, "%d\n", ubi->bad_peb_count);
	else if (attr == &dev_max_vol_count)
		return sprintf(buf, "%d\n", ubi->vtbl_slots);
	else if (attr == &dev_min_io_size)
		return sprintf(buf, "%d\n", ubi->min_io_size);
	else if (attr == &dev_bgt_enabled)
		return sprintf(buf, "%d\n", ubi->thread_enabled);
	else
		BUG();

	return 0;
}

/* Fake "release" method for UBI devices */
static void dev_release(struct device *dev) { }

/**
 * ubi_sysfs_init - initialize sysfs for an UBI device.
 * @ubi: UBI device description object
 *
 * This function returns zero in case of success and a negative error code in
 * case of failure.
 */
static int ubi_sysfs_init(struct ubi_device *ubi)
{
	int err;

	ubi->dev.release = dev_release;
	ubi->dev.devt = MKDEV(ubi->major, 0);
	ubi->dev.class = ubi_class;
	sprintf(&ubi->dev.bus_id[0], UBI_NAME_STR"%d", ubi->ubi_num);
	err = device_register(&ubi->dev);
	if (err)
		goto out;

	err = device_create_file(&ubi->dev, &dev_eraseblock_size);
	if (err)
		goto out_unregister;
	err = device_create_file(&ubi->dev, &dev_avail_eraseblocks);
	if (err)
		goto out_eraseblock_size;
	err = device_create_file(&ubi->dev, &dev_total_eraseblocks);
	if (err)
		goto out_avail_eraseblocks;
	err = device_create_file(&ubi->dev, &dev_volumes_count);
	if (err)
		goto out_total_eraseblocks;
	err = device_create_file(&ubi->dev, &dev_max_ec);
	if (err)
		goto out_volumes_count;
	err = device_create_file(&ubi->dev, &dev_reserved_for_bad);
	if (err)
		goto out_volumes_max_ec;
	err = device_create_file(&ubi->dev, &dev_bad_peb_count);
	if (err)
		goto out_reserved_for_bad;
	err = device_create_file(&ubi->dev, &dev_max_vol_count);
	if (err)
		goto out_bad_peb_count;
	err = device_create_file(&ubi->dev, &dev_min_io_size);
	if (err)
		goto out_max_vol_count;
	err = device_create_file(&ubi->dev, &dev_bgt_enabled);
	if (err)
		goto out_min_io_size;

	return 0;

out_min_io_size:
	device_remove_file(&ubi->dev, &dev_min_io_size);
out_max_vol_count:
	device_remove_file(&ubi->dev, &dev_max_vol_count);
out_bad_peb_count:
	device_remove_file(&ubi->dev, &dev_bad_peb_count);
out_reserved_for_bad:
	device_remove_file(&ubi->dev, &dev_reserved_for_bad);
out_volumes_max_ec:
	device_remove_file(&ubi->dev, &dev_max_ec);
out_volumes_count:
	device_remove_file(&ubi->dev, &dev_volumes_count);
out_total_eraseblocks:
	device_remove_file(&ubi->dev, &dev_total_eraseblocks);
out_avail_eraseblocks:
	device_remove_file(&ubi->dev, &dev_avail_eraseblocks);
out_eraseblock_size:
	device_remove_file(&ubi->dev, &dev_eraseblock_size);
out_unregister:
	device_unregister(&ubi->dev);
out:
	ubi_err("failed to initialize sysfs for %s", ubi->ubi_name);
	return err;
}

/**
 * ubi_sysfs_close - close sysfs for an UBI device.
 * @ubi: UBI device description object
 */
static void ubi_sysfs_close(struct ubi_device *ubi)
{
	device_remove_file(&ubi->dev, &dev_bgt_enabled);
	device_remove_file(&ubi->dev, &dev_min_io_size);
	device_remove_file(&ubi->dev, &dev_max_vol_count);
	device_remove_file(&ubi->dev, &dev_bad_peb_count);
	device_remove_file(&ubi->dev, &dev_reserved_for_bad);
	device_remove_file(&ubi->dev, &dev_max_ec);
	device_remove_file(&ubi->dev, &dev_volumes_count);
	device_remove_file(&ubi->dev, &dev_total_eraseblocks);
	device_remove_file(&ubi->dev, &dev_avail_eraseblocks);
	device_remove_file(&ubi->dev, &dev_eraseblock_size);
	device_unregister(&ubi->dev);
}

/**
 * kill_volumes - destroy all volumes.
 * @ubi: UBI device description object
 */
static void kill_volumes(struct ubi_device *ubi)
{
	int i;

	for (i = 0; i < ubi->vtbl_slots; i++)
		if (ubi->volumes[i])
			ubi_free_volume(ubi, i);
}

/**
 * uif_init - initialize user interfaces for an UBI device.
 * @ubi: UBI device description object
 *
 * This function returns zero in case of success and a negative error code in
 * case of failure.
 */
static int uif_init(struct ubi_device *ubi)
{
	int i, err;
	dev_t dev;

	mutex_init(&ubi->vtbl_mutex);
	spin_lock_init(&ubi->volumes_lock);

	sprintf(ubi->ubi_name, UBI_NAME_STR "%d", ubi->ubi_num);

	/*
	 * Major numbers for the UBI character devices are allocated
	 * dynamically. Major numbers of volume character devices are
	 * equivalent to ones of the corresponding UBI character device. Minor
	 * numbers of UBI character devices are 0, while minor numbers of
	 * volume character devices start from 1. Thus, we allocate one major
	 * number and ubi->vtbl_slots + 1 minor numbers.
	 */
	err = alloc_chrdev_region(&dev, 0, ubi->vtbl_slots + 1, ubi->ubi_name);
	if (err) {
		ubi_err("cannot register UBI character devices");
		return err;
	}

	cdev_init(&ubi->cdev, &ubi_cdev_operations);
	ubi->major = MAJOR(dev);
	dbg_msg("%s major is %u", ubi->ubi_name, ubi->major);
	ubi->cdev.owner = THIS_MODULE;

	dev = MKDEV(ubi->major, 0);
	err = cdev_add(&ubi->cdev, dev, 1);
	if (err) {
		ubi_err("cannot add character device %s", ubi->ubi_name);
		goto out_unreg;
	}

	err = ubi_sysfs_init(ubi);
	if (err)
		goto out_cdev;

	for (i = 0; i < ubi->vtbl_slots; i++)
		if (ubi->volumes[i]) {
			err = ubi_add_volume(ubi, i);
			if (err)
				goto out_volumes;
		}

	return 0;

out_volumes:
	kill_volumes(ubi);
	ubi_sysfs_close(ubi);
out_cdev:
	cdev_del(&ubi->cdev);
out_unreg:
	unregister_chrdev_region(MKDEV(ubi->major, 0),
				 ubi->vtbl_slots + 1);
	return err;
}

/**
 * uif_close - close user interfaces for an UBI device.
 * @ubi: UBI device description object
 */
static void uif_close(struct ubi_device *ubi)
{
	kill_volumes(ubi);
	ubi_sysfs_close(ubi);
	cdev_del(&ubi->cdev);
	unregister_chrdev_region(MKDEV(ubi->major, 0), ubi->vtbl_slots + 1);
}

/**
 * attach_by_scanning - attach an MTD device using scanning method.
 * @ubi: UBI device descriptor
 *
 * This function returns zero in case of success and a negative error code in
 * case of failure.
 *
 * Note, currently this is the only method to attach UBI devices. Hopefully in
 * the future we'll have more scalable attaching methods and avoid full media
 * scanning. But even in this case scanning will be needed as a fall-back
 * attaching method if there are some on-flash table corruptions.
 */
static int attach_by_scanning(struct ubi_device *ubi)
{
	int err;
	struct ubi_scan_info *si;

	si = ubi_scan(ubi);
	if (IS_ERR(si))
		return PTR_ERR(si);

	ubi->bad_peb_count = si->bad_peb_count;
	ubi->good_peb_count = ubi->peb_count - ubi->bad_peb_count;
	ubi->max_ec = si->max_ec;
	ubi->mean_ec = si->mean_ec;

	err = ubi_read_volume_table(ubi, si);
	if (err)
		goto out_si;

	err = ubi_wl_init_scan(ubi, si);
	if (err)
		goto out_vtbl;

	err = ubi_eba_init_scan(ubi, si);
	if (err)
		goto out_wl;

	ubi_scan_destroy_si(si);
	return 0;

out_wl:
	ubi_wl_close(ubi);
out_vtbl:
	kfree(ubi->vtbl);
out_si:
	ubi_scan_destroy_si(si);
	return err;
}

/**
 * io_init - initialize I/O unit for a given UBI device.
 * @ubi: UBI device description object
 *
 * If @ubi->vid_hdr_offset or @ubi->leb_start is zero, default offsets are
 * assumed:
 *   o EC header is always at offset zero - this cannot be changed;
 *   o VID header starts just after the EC header at the closest address
 *   aligned to @io->@hdrs_min_io_size;
 *   o data starts just after the VID header at the closest address aligned to
 *     @io->@min_io_size
 *
 * This function returns zero in case of success and a negative error code in
 * case of failure.
 */
static int io_init(struct ubi_device *ubi)
{
	if (ubi->mtd->numeraseregions != 0) {
		/*
		 * Some flashes have several erase regions. Different regions
		 * may have different eraseblock size and other
		 * characteristics. It looks like mostly multi-region flashes
		 * have one "main" region and one or more small regions to
		 * store boot loader code or boot parameters or whatever. I
		 * guess we should just pick the largest region. But this is
		 * not implemented.
		 */
		ubi_err("multiple regions, not implemented");
		return -EINVAL;
	}

	/*
	 * Note, in this implementation we support MTD devices with 0x7FFFFFFF
	 * physical eraseblocks maximum.
	 */

	ubi->peb_size   = ubi->mtd->erasesize;
	ubi->peb_count  = ubi->mtd->size / ubi->mtd->erasesize;
	ubi->flash_size = ubi->mtd->size;

	if (ubi->mtd->block_isbad && ubi->mtd->block_markbad)
		ubi->bad_allowed = 1;

	ubi->min_io_size = ubi->mtd->writesize;
	ubi->hdrs_min_io_size = ubi->mtd->writesize >> ubi->mtd->subpage_sft;

	/* Make sure minimal I/O unit is power of 2 */
	if (ubi->min_io_size == 0 ||
	    (ubi->min_io_size & (ubi->min_io_size - 1))) {
		ubi_err("bad min. I/O unit");
		return -EINVAL;
	}

	ubi_assert(ubi->hdrs_min_io_size > 0);
	ubi_assert(ubi->hdrs_min_io_size <= ubi->min_io_size);
	ubi_assert(ubi->min_io_size % ubi->hdrs_min_io_size == 0);

	/* Calculate default aligned sizes of EC and VID headers */
	ubi->ec_hdr_alsize = ALIGN(UBI_EC_HDR_SIZE, ubi->hdrs_min_io_size);
	ubi->vid_hdr_alsize = ALIGN(UBI_VID_HDR_SIZE, ubi->hdrs_min_io_size);

	dbg_msg("min_io_size      %d", ubi->min_io_size);
	dbg_msg("hdrs_min_io_size %d", ubi->hdrs_min_io_size);
	dbg_msg("ec_hdr_alsize    %d", ubi->ec_hdr_alsize);
	dbg_msg("vid_hdr_alsize   %d", ubi->vid_hdr_alsize);

	if (ubi->vid_hdr_offset == 0)
		/* Default offset */
		ubi->vid_hdr_offset = ubi->vid_hdr_aloffset =
				      ubi->ec_hdr_alsize;
	else {
		ubi->vid_hdr_aloffset = ubi->vid_hdr_offset &
						~(ubi->hdrs_min_io_size - 1);
		ubi->vid_hdr_shift = ubi->vid_hdr_offset -
						ubi->vid_hdr_aloffset;
	}

	/* Similar for the data offset */
	if (ubi->leb_start == 0) {
		ubi->leb_start = ubi->vid_hdr_offset + ubi->vid_hdr_alsize;
		ubi->leb_start = ALIGN(ubi->leb_start, ubi->min_io_size);
	}

	dbg_msg("vid_hdr_offset   %d", ubi->vid_hdr_offset);
	dbg_msg("vid_hdr_aloffset %d", ubi->vid_hdr_aloffset);
	dbg_msg("vid_hdr_shift    %d", ubi->vid_hdr_shift);
	dbg_msg("leb_start        %d", ubi->leb_start);

	/* The shift must be aligned to 32-bit boundary */
	if (ubi->vid_hdr_shift % 4) {
		ubi_err("unaligned VID header shift %d",
			ubi->vid_hdr_shift);
		return -EINVAL;
	}

	/* Check sanity */
	if (ubi->vid_hdr_offset < UBI_EC_HDR_SIZE ||
	    ubi->leb_start < ubi->vid_hdr_offset + UBI_VID_HDR_SIZE ||
	    ubi->leb_start > ubi->peb_size - UBI_VID_HDR_SIZE ||
	    ubi->leb_start % ubi->min_io_size) {
		ubi_err("bad VID header (%d) or data offsets (%d)",
			ubi->vid_hdr_offset, ubi->leb_start);
		return -EINVAL;
	}

	/*
	 * It may happen that EC and VID headers are situated in one minimal
	 * I/O unit. In this case we can only accept this UBI image in
	 * read-only mode.
	 */
	if (ubi->vid_hdr_offset + UBI_VID_HDR_SIZE <= ubi->hdrs_min_io_size) {
		ubi_warn("EC and VID headers are in the same minimal I/O unit, "
			 "switch to read-only mode");
		ubi->ro_mode = 1;
	}

	ubi->leb_size = ubi->peb_size - ubi->leb_start;

	if (!(ubi->mtd->flags & MTD_WRITEABLE)) {
		ubi_msg("MTD device %d is write-protected, attach in "
			"read-only mode", ubi->mtd->index);
		ubi->ro_mode = 1;
	}

	dbg_msg("leb_size         %d", ubi->leb_size);
	dbg_msg("ro_mode          %d", ubi->ro_mode);

	/*
	 * Note, ideally, we have to initialize ubi->bad_peb_count here. But
	 * unfortunately, MTD does not provide this information. We should loop
	 * over all physical eraseblocks and invoke mtd->block_is_bad() for
	 * each physical eraseblock. So, we skip ubi->bad_peb_count
	 * uninitialized and initialize it after scanning.
	 */

	return 0;
}

/**
 * attach_mtd_dev - attach an MTD device.
 * @mtd_dev: MTD device name or number string
 * @vid_hdr_offset: VID header offset
 * @data_offset: data offset
 *
 * This function attaches an MTD device to UBI. It first treats @mtd_dev as the
 * MTD device name, and tries to open it by this name. If it is unable to open,
 * it tries to convert @mtd_dev to an integer and open the MTD device by its
 * number. Returns zero in case of success and a negative error code in case of
 * failure.
 */
static int attach_mtd_dev(const char *mtd_dev, int vid_hdr_offset,
			  int data_offset)
{
	struct ubi_device *ubi;
	struct mtd_info *mtd;
	int i, err;

	mtd = get_mtd_device_nm(mtd_dev);
	if (IS_ERR(mtd)) {
		int mtd_num;
		char *endp;

		if (PTR_ERR(mtd) != -ENODEV)
			return PTR_ERR(mtd);

		/*
		 * Probably this is not MTD device name but MTD device number -
		 * check this out.
		 */
		mtd_num = simple_strtoul(mtd_dev, &endp, 0);
		if (*endp != '\0' || mtd_dev == endp) {
			ubi_err("incorrect MTD device: \"%s\"", mtd_dev);
			return -ENODEV;
		}

		mtd = get_mtd_device(NULL, mtd_num);
		if (IS_ERR(mtd))
			return PTR_ERR(mtd);
	}

	/* Check if we already have the same MTD device attached */
	for (i = 0; i < ubi_devices_cnt; i++)
		if (ubi_devices[i]->mtd->index == mtd->index) {
			ubi_err("mtd%d is already attached to ubi%d",
				mtd->index, i);
			err = -EINVAL;
			goto out_mtd;
		}

	ubi = ubi_devices[ubi_devices_cnt] = kzalloc(sizeof(struct ubi_device),
						      GFP_KERNEL);
	if (!ubi) {
		err = -ENOMEM;
		goto out_mtd;
	}

	ubi->ubi_num = ubi_devices_cnt;
	ubi->mtd = mtd;

	dbg_msg("attaching mtd%d to ubi%d: VID header offset %d data offset %d",
		ubi->mtd->index, ubi_devices_cnt, vid_hdr_offset, data_offset);

	ubi->vid_hdr_offset = vid_hdr_offset;
	ubi->leb_start = data_offset;
	err = io_init(ubi);
	if (err)
		goto out_free;

	err = attach_by_scanning(ubi);
	if (err) {
		dbg_err("failed to attach by scanning, error %d", err);
		goto out_free;
	}

	err = uif_init(ubi);
	if (err)
		goto out_detach;

	ubi_devices_cnt += 1;

	ubi_msg("attached mtd%d to ubi%d", ubi->mtd->index, ubi_devices_cnt);
	ubi_msg("MTD device name:            \"%s\"", ubi->mtd->name);
	ubi_msg("MTD device size:            %llu MiB", ubi->flash_size >> 20);
	ubi_msg("physical eraseblock size:   %d bytes (%d KiB)",
		ubi->peb_size, ubi->peb_size >> 10);
	ubi_msg("logical eraseblock size:    %d bytes", ubi->leb_size);
	ubi_msg("number of good PEBs:        %d", ubi->good_peb_count);
	ubi_msg("number of bad PEBs:         %d", ubi->bad_peb_count);
	ubi_msg("smallest flash I/O unit:    %d", ubi->min_io_size);
	ubi_msg("VID header offset:          %d (aligned %d)",
		ubi->vid_hdr_offset, ubi->vid_hdr_aloffset);
	ubi_msg("data offset:                %d", ubi->leb_start);
	ubi_msg("max. allowed volumes:       %d", ubi->vtbl_slots);
	ubi_msg("wear-leveling threshold:    %d", CONFIG_MTD_UBI_WL_THRESHOLD);
	ubi_msg("number of internal volumes: %d", UBI_INT_VOL_COUNT);
	ubi_msg("number of user volumes:     %d",
		ubi->vol_count - UBI_INT_VOL_COUNT);
	ubi_msg("available PEBs:             %d", ubi->avail_pebs);
	ubi_msg("total number of reserved PEBs: %d", ubi->rsvd_pebs);
	ubi_msg("number of PEBs reserved for bad PEB handling: %d",
		ubi->beb_rsvd_pebs);
	ubi_msg("max/mean erase counter: %d/%d", ubi->max_ec, ubi->mean_ec);

	/* Enable the background thread */
	if (!DBG_DISABLE_BGT) {
		ubi->thread_enabled = 1;
		wake_up_process(ubi->bgt_thread);
	}

	return 0;

out_detach:
	ubi_eba_close(ubi);
	ubi_wl_close(ubi);
	kfree(ubi->vtbl);
out_free:
	kfree(ubi);
out_mtd:
	put_mtd_device(mtd);
	ubi_devices[ubi_devices_cnt] = NULL;
	return err;
}

/**
 * detach_mtd_dev - detach an MTD device.
 * @ubi: UBI device description object
 */
static void detach_mtd_dev(struct ubi_device *ubi)
{
	int ubi_num = ubi->ubi_num, mtd_num = ubi->mtd->index;

	dbg_msg("detaching mtd%d from ubi%d", ubi->mtd->index, ubi_num);
	uif_close(ubi);
	ubi_eba_close(ubi);
	ubi_wl_close(ubi);
	kfree(ubi->vtbl);
	put_mtd_device(ubi->mtd);
	kfree(ubi_devices[ubi_num]);
	ubi_devices[ubi_num] = NULL;
	ubi_devices_cnt -= 1;
	ubi_assert(ubi_devices_cnt >= 0);
	ubi_msg("mtd%d is detached from ubi%d", mtd_num, ubi_num);
}

static int __init ubi_init(void)
{
	int err, i, k;

	/* Ensure that EC and VID headers have correct size */
	BUILD_BUG_ON(sizeof(struct ubi_ec_hdr) != 64);
	BUILD_BUG_ON(sizeof(struct ubi_vid_hdr) != 64);

	if (mtd_devs > UBI_MAX_DEVICES) {
		printk("UBI error: too many MTD devices, maximum is %d\n",
		       UBI_MAX_DEVICES);
		return -EINVAL;
	}

	ubi_class = class_create(THIS_MODULE, UBI_NAME_STR);
	if (IS_ERR(ubi_class))
		return PTR_ERR(ubi_class);

	err = class_create_file(ubi_class, &ubi_version);
	if (err)
		goto out_class;

	/* Attach MTD devices */
	for (i = 0; i < mtd_devs; i++) {
		struct mtd_dev_param *p = &mtd_dev_param[i];

		cond_resched();

		if (!p->name) {
			dbg_err("empty name");
			err = -EINVAL;
			goto out_detach;
		}

		err = attach_mtd_dev(p->name, p->vid_hdr_offs, p->data_offs);
		if (err)
			goto out_detach;
	}

	return 0;

out_detach:
	for (k = 0; k < i; k++)
		detach_mtd_dev(ubi_devices[k]);
	class_remove_file(ubi_class, &ubi_version);
out_class:
	class_destroy(ubi_class);
	return err;
}
module_init(ubi_init);

static void __exit ubi_exit(void)
{
	int i, n = ubi_devices_cnt;

	for (i = 0; i < n; i++)
		detach_mtd_dev(ubi_devices[i]);
	class_remove_file(ubi_class, &ubi_version);
	class_destroy(ubi_class);
}
module_exit(ubi_exit);

/**
 * bytes_str_to_int - convert a string representing number of bytes to an
 * integer.
 * @str: the string to convert
 *
 * This function returns positive resulting integer in case of success and a
 * negative error code in case of failure.
 */
static int __init bytes_str_to_int(const char *str)
{
	char *endp;
	unsigned long result;

	result = simple_strtoul(str, &endp, 0);
	if (str == endp || result < 0) {
		printk("UBI error: incorrect bytes count: \"%s\"\n", str);
		return -EINVAL;
	}

	switch (*endp) {
	case 'G':
		result *= 1024;
	case 'M':
		result *= 1024;
	case 'K':
	case 'k':
		result *= 1024;
		if (endp[1] == 'i' && (endp[2] == '\0' ||
			  endp[2] == 'B'  || endp[2] == 'b'))
			endp += 2;
	case '\0':
		break;
	default:
		printk("UBI error: incorrect bytes count: \"%s\"\n", str);
		return -EINVAL;
	}

	return result;
}

/**
 * ubi_mtd_param_parse - parse the 'mtd=' UBI parameter.
 * @val: the parameter value to parse
 * @kp: not used
 *
 * This function returns zero in case of success and a negative error code in
 * case of error.
 */
static int __init ubi_mtd_param_parse(const char *val, struct kernel_param *kp)
{
	int i, len;
	struct mtd_dev_param *p;
	char buf[MTD_PARAM_LEN_MAX];
	char *pbuf = &buf[0];
	char *tokens[3] = {NULL, NULL, NULL};

	if (mtd_devs == UBI_MAX_DEVICES) {
		printk("UBI error: too many parameters, max. is %d\n",
		       UBI_MAX_DEVICES);
		return -EINVAL;
	}

	len = strnlen(val, MTD_PARAM_LEN_MAX);
	if (len == MTD_PARAM_LEN_MAX) {
		printk("UBI error: parameter \"%s\" is too long, max. is %d\n",
		       val, MTD_PARAM_LEN_MAX);
		return -EINVAL;
	}

	if (len == 0) {
		printk("UBI warning: empty 'mtd=' parameter - ignored\n");
		return 0;
	}

	strcpy(buf, val);

	/* Get rid of the final newline */
	if (buf[len - 1] == '\n')
		buf[len - 1] = 0;

	for (i = 0; i < 3; i++)
		tokens[i] = strsep(&pbuf, ",");

	if (pbuf) {
		printk("UBI error: too many arguments at \"%s\"\n", val);
		return -EINVAL;
	}

	if (tokens[0] == '\0')
		return -EINVAL;

	p = &mtd_dev_param[mtd_devs];
	strcpy(&p->name[0], tokens[0]);

	if (tokens[1])
		p->vid_hdr_offs = bytes_str_to_int(tokens[1]);
	if (tokens[2])
		p->data_offs = bytes_str_to_int(tokens[2]);

	if (p->vid_hdr_offs < 0)
		return p->vid_hdr_offs;
	if (p->data_offs < 0)
		return p->data_offs;

	mtd_devs += 1;
	return 0;
}

module_param_call(mtd, ubi_mtd_param_parse, NULL, NULL, 000);
MODULE_PARM_DESC(mtd, "MTD devices to attach. Parameter format: "
		      "mtd=<name|num>[,<vid_hdr_offs>,<data_offs>]. "
		      "Multiple \"mtd\" parameters may be specified.\n"
		      "MTD devices may be specified by their number or name. "
		      "Optional \"vid_hdr_offs\" and \"data_offs\" parameters "
		      "specify UBI VID header position and data starting "
		      "position to be used by UBI.\n"
		      "Example: mtd=content,1984,2048 mtd=4 - attach MTD device"
		      "with name content using VID header offset 1984 and data "
		      "start 2048, and MTD device number 4 using default "
		      "offsets");

MODULE_VERSION(__stringify(UBI_VERSION));
MODULE_DESCRIPTION("UBI - Unsorted Block Images");
MODULE_AUTHOR("Artem Bityutskiy");
MODULE_LICENSE("GPL");