aboutsummaryrefslogtreecommitdiff
path: root/drivers/mtd/ubi/gluebi.c
blob: 941bc3c05d6e51232eabfbdd6db08a0248bb4328 (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
/*
 * Copyright (c) International Business Machines Corp., 2006
 *
 * 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), Joern Engel
 */

/*
 * This is a small driver which implements fake MTD devices on top of UBI
 * volumes. This sounds strange, but it is in fact quite useful to make
 * MTD-oriented software (including all the legacy software) work on top of
 * UBI.
 *
 * Gluebi emulates MTD devices of "MTD_UBIVOLUME" type. Their minimal I/O unit
 * size (@mtd->writesize) is equivalent to the UBI minimal I/O unit. The
 * eraseblock size is equivalent to the logical eraseblock size of the volume.
 */

#include <linux/err.h>
#include <linux/list.h>
#include <linux/slab.h>
#include <linux/sched.h>
#include <linux/math64.h>
#include <linux/module.h>
#include <linux/mutex.h>
#include <linux/mtd/ubi.h>
#include <linux/mtd/mtd.h>
#include "ubi-media.h"

#define err_msg(fmt, ...)                                   \
	printk(KERN_DEBUG "gluebi (pid %d): %s: " fmt "\n", \
	       current->pid, __func__, ##__VA_ARGS__)

/**
 * struct gluebi_device - a gluebi device description data structure.
 * @mtd: emulated MTD device description object
 * @refcnt: gluebi device reference count
 * @desc: UBI volume descriptor
 * @ubi_num: UBI device number this gluebi device works on
 * @vol_id: ID of UBI volume this gluebi device works on
 * @list: link in a list of gluebi devices
 */
struct gluebi_device {
	struct mtd_info mtd;
	int refcnt;
	struct ubi_volume_desc *desc;
	int ubi_num;
	int vol_id;
	struct list_head list;
};

/* List of all gluebi devices */
static LIST_HEAD(gluebi_devices);
static DEFINE_MUTEX(devices_mutex);

/**
 * find_gluebi_nolock - find a gluebi device.
 * @ubi_num: UBI device number
 * @vol_id: volume ID
 *
 * This function seraches for gluebi device corresponding to UBI device
 * @ubi_num and UBI volume @vol_id. Returns the gluebi device description
 * object in case of success and %NULL in case of failure. The caller has to
 * have the &devices_mutex locked.
 */
static struct gluebi_device *find_gluebi_nolock(int ubi_num, int vol_id)
{
	struct gluebi_device *gluebi;

	list_for_each_entry(gluebi, &gluebi_devices, list)
		if (gluebi->ubi_num == ubi_num && gluebi->vol_id == vol_id)
			return gluebi;
	return NULL;
}

/**
 * gluebi_get_device - get MTD device reference.
 * @mtd: the MTD device description object
 *
 * This function is called every time the MTD device is being opened and
 * implements the MTD get_device() operation. Returns zero in case of success
 * and a negative error code in case of failure.
 */
static int gluebi_get_device(struct mtd_info *mtd)
{
	struct gluebi_device *gluebi;
	int ubi_mode = UBI_READONLY;

	if (!try_module_get(THIS_MODULE))
		return -ENODEV;

	if (mtd->flags & MTD_WRITEABLE)
		ubi_mode = UBI_READWRITE;

	gluebi = container_of(mtd, struct gluebi_device, mtd);
	mutex_lock(&devices_mutex);
	if (gluebi->refcnt > 0) {
		/*
		 * The MTD device is already referenced and this is just one
		 * more reference. MTD allows many users to open the same
		 * volume simultaneously and do not distinguish between
		 * readers/writers/exclusive openers as UBI does. So we do not
		 * open the UBI volume again - just increase the reference
		 * counter and return.
		 */
		gluebi->refcnt += 1;
		mutex_unlock(&devices_mutex);
		return 0;
	}

	/*
	 * This is the first reference to this UBI volume via the MTD device
	 * interface. Open the corresponding volume in read-write mode.
	 */
	gluebi->desc = ubi_open_volume(gluebi->ubi_num, gluebi->vol_id,
				       ubi_mode);
	if (IS_ERR(gluebi->desc)) {
		mutex_unlock(&devices_mutex);
		module_put(THIS_MODULE);
		return PTR_ERR(gluebi->desc);
	}
	gluebi->refcnt += 1;
	mutex_unlock(&devices_mutex);
	return 0;
}

/**
 * gluebi_put_device - put MTD device reference.
 * @mtd: the MTD device description object
 *
 * This function is called every time the MTD device is being put. Returns
 * zero in case of success and a negative error code in case of failure.
 */
static void gluebi_put_device(struct mtd_info *mtd)
{
	struct gluebi_device *gluebi;

	gluebi = container_of(mtd, struct gluebi_device, mtd);
	mutex_lock(&devices_mutex);
	gluebi->refcnt -= 1;
	if (gluebi->refcnt == 0)
		ubi_close_volume(gluebi->desc);
	module_put(THIS_MODULE);
	mutex_unlock(&devices_mutex);
}

/**
 * gluebi_read - read operation of emulated MTD devices.
 * @mtd: MTD device description object
 * @from: absolute offset from where to read
 * @len: how many bytes to read
 * @retlen: count of read bytes is returned here
 * @buf: buffer to store the read data
 *
 * This function returns zero in case of success and a negative error code in
 * case of failure.
 */
static int gluebi_read(struct mtd_info *mtd, loff_t from, size_t len,
		       size_t *retlen, unsigned char *buf)
{
	int err = 0, lnum, offs, total_read;
	struct gluebi_device *gluebi;

	if (len < 0 || from < 0 || from + len > mtd->size)
		return -EINVAL;

	gluebi = container_of(mtd, struct gluebi_device, mtd);

	lnum = div_u64_rem(from, mtd->erasesize, &offs);
	total_read = len;
	while (total_read) {
		size_t to_read = mtd->erasesize - offs;

		if (to_read > total_read)
			to_read = total_read;

		err = ubi_read(gluebi->desc, lnum, buf, offs, to_read);
		if (err)
			break;

		lnum += 1;
		offs = 0;
		total_read -= to_read;
		buf += to_read;
	}

	*retlen = len - total_read;
	return err;
}

/**
 * gluebi_write - write operation of emulated MTD devices.
 * @mtd: MTD device description object
 * @to: absolute offset where to write
 * @len: how many bytes to write
 * @retlen: count of written bytes is returned here
 * @buf: buffer with data to write
 *
 * This function returns zero in case of success and a negative error code in
 * case of failure.
 */
static int gluebi_write(struct mtd_info *mtd, loff_t to, size_t len,
			size_t *retlen, const u_char *buf)
{
	int err = 0, lnum, offs, total_written;
	struct gluebi_device *gluebi;

	if (len < 0 || to < 0 || len + to > mtd->size)
		return -EINVAL;

	gluebi = container_of(mtd, struct gluebi_device, mtd);

	if (!(mtd->flags & MTD_WRITEABLE))
		return -EROFS;

	lnum = div_u64_rem(to, mtd->erasesize, &offs);

	if (len % mtd->writesize || offs % mtd->writesize)
		return -EINVAL;

	total_written = len;
	while (total_written) {
		size_t to_write = mtd->erasesize - offs;

		if (to_write > total_written)
			to_write = total_written;

		err = ubi_write(gluebi->desc, lnum, buf, offs, to_write);
		if (err)
			break;

		lnum += 1;
		offs = 0;
		total_written -= to_write;
		buf += to_write;
	}

	*retlen = len - total_written;
	return err;
}

/**
 * gluebi_erase - erase operation of emulated MTD devices.
 * @mtd: the MTD device description object
 * @instr: the erase operation description
 *
 * This function calls the erase callback when finishes. Returns zero in case
 * of success and a negative error code in case of failure.
 */
static int gluebi_erase(struct mtd_info *mtd, struct erase_info *instr)
{
	int err, i, lnum, count;
	struct gluebi_device *gluebi;

	if (instr->addr < 0 || instr->addr > mtd->size - mtd->erasesize)
		return -EINVAL;
	if (instr->len < 0 || instr->addr + instr->len > mtd->size)
		return -EINVAL;
	if (mtd_mod_by_ws(instr->addr, mtd) || mtd_mod_by_ws(instr->len, mtd))
		return -EINVAL;

	lnum = mtd_div_by_eb(instr->addr, mtd);
	count = mtd_div_by_eb(instr->len, mtd);

	gluebi = container_of(mtd, struct gluebi_device, mtd);

	if (!(mtd->flags & MTD_WRITEABLE))
		return -EROFS;

	for (i = 0; i < count - 1; i++) {
		err = ubi_leb_unmap(gluebi->desc, lnum + i);
		if (err)
			goto out_err;
	}
	/*
	 * MTD erase operations are synchronous, so we have to make sure the
	 * physical eraseblock is wiped out.
	 *
	 * Thus, perform leb_erase instead of leb_unmap operation - leb_erase
	 * will wait for the end of operations
	 */
	err = ubi_leb_erase(gluebi->desc, lnum + i);
	if (err)
		goto out_err;

	instr->state = MTD_ERASE_DONE;
	mtd_erase_callback(instr);
	return 0;

out_err:
	instr->state = MTD_ERASE_FAILED;
	instr->fail_addr = (long long)lnum * mtd->erasesize;
	return err;
}

/**
 * gluebi_create - create a gluebi device for an UBI volume.
 * @di: UBI device description object
 * @vi: UBI volume description object
 *
 * This function is called when a new UBI volume is created in order to create
 * corresponding fake MTD device. Returns zero in case of success and a
 * negative error code in case of failure.
 */
static int gluebi_create(struct ubi_device_info *di,
			 struct ubi_volume_info *vi)
{
	struct gluebi_device *gluebi, *g;
	struct mtd_info *mtd;

	gluebi = kzalloc(sizeof(struct gluebi_device), GFP_KERNEL);
	if (!gluebi)
		return -ENOMEM;

	mtd = &gluebi->mtd;
	mtd->name = kmemdup(vi->name, vi->name_len + 1, GFP_KERNEL);
	if (!mtd->name) {
		kfree(gluebi);
		return -ENOMEM;
	}

	gluebi->vol_id = vi->vol_id;
	gluebi->ubi_num = vi->ubi_num;
	mtd->type = MTD_UBIVOLUME;
	if (!di->ro_mode)
		mtd->flags = MTD_WRITEABLE;
	mtd->owner      = THIS_MODULE;
	mtd->writesize  = di->min_io_size;
	mtd->erasesize  = vi->usable_leb_size;
	mtd->read       = gluebi_read;
	mtd->write      = gluebi_write;
	mtd->erase      = gluebi_erase;
	mtd->get_device = gluebi_get_device;
	mtd->put_device = gluebi_put_device;

	/*
	 * In case of dynamic a volume, MTD device size is just volume size. In
	 * case of a static volume the size is equivalent to the amount of data
	 * bytes.
	 */
	if (vi->vol_type == UBI_DYNAMIC_VOLUME)
		mtd->size = (unsigned long long)vi->usable_leb_size * vi->size;
	else
		mtd->size = vi->used_bytes;

	/* Just a sanity check - make sure this gluebi device does not exist */
	mutex_lock(&devices_mutex);
	g = find_gluebi_nolock(vi->ubi_num, vi->vol_id);
	if (g)
		err_msg("gluebi MTD device %d form UBI device %d volume %d "
			"already exists", g->mtd.index, vi->ubi_num,
			vi->vol_id);
	mutex_unlock(&devices_mutex);

	if (mtd_device_register(mtd, NULL, 0)) {
		err_msg("cannot add MTD device");
		kfree(mtd->name);
		kfree(gluebi);
		return -ENFILE;
	}

	mutex_lock(&devices_mutex);
	list_add_tail(&gluebi->list, &gluebi_devices);
	mutex_unlock(&devices_mutex);
	return 0;
}

/**
 * gluebi_remove - remove a gluebi device.
 * @vi: UBI volume description object
 *
 * This function is called when an UBI volume is removed and it removes
 * corresponding fake MTD device. Returns zero in case of success and a
 * negative error code in case of failure.
 */
static int gluebi_remove(struct ubi_volume_info *vi)
{
	int err = 0;
	struct mtd_info *mtd;
	struct gluebi_device *gluebi;

	mutex_lock(&devices_mutex);
	gluebi = find_gluebi_nolock(vi->ubi_num, vi->vol_id);
	if (!gluebi) {
		err_msg("got remove notification for unknown UBI device %d "
			"volume %d", vi->ubi_num, vi->vol_id);
		err = -ENOENT;
	} else if (gluebi->refcnt)
		err = -EBUSY;
	else
		list_del(&gluebi->list);
	mutex_unlock(&devices_mutex);
	if (err)
		return err;

	mtd = &gluebi->mtd;
	err = mtd_device_unregister(mtd);
	if (err) {
		err_msg("cannot remove fake MTD device %d, UBI device %d, "
			"volume %d, error %d", mtd->index, gluebi->ubi_num,
			gluebi->vol_id, err);
		mutex_lock(&devices_mutex);
		list_add_tail(&gluebi->list, &gluebi_devices);
		mutex_unlock(&devices_mutex);
		return err;
	}

	kfree(mtd->name);
	kfree(gluebi);
	return 0;
}

/**
 * gluebi_updated - UBI volume was updated notifier.
 * @vi: volume info structure
 *
 * This function is called every time an UBI volume is updated. It does nothing
 * if te volume @vol is dynamic, and changes MTD device size if the
 * volume is static. This is needed because static volumes cannot be read past
 * data they contain. This function returns zero in case of success and a
 * negative error code in case of error.
 */
static int gluebi_updated(struct ubi_volume_info *vi)
{
	struct gluebi_device *gluebi;

	mutex_lock(&devices_mutex);
	gluebi = find_gluebi_nolock(vi->ubi_num, vi->vol_id);
	if (!gluebi) {
		mutex_unlock(&devices_mutex);
		err_msg("got update notification for unknown UBI device %d "
			"volume %d", vi->ubi_num, vi->vol_id);
		return -ENOENT;
	}

	if (vi->vol_type == UBI_STATIC_VOLUME)
		gluebi->mtd.size = vi->used_bytes;
	mutex_unlock(&devices_mutex);
	return 0;
}

/**
 * gluebi_resized - UBI volume was re-sized notifier.
 * @vi: volume info structure
 *
 * This function is called every time an UBI volume is re-size. It changes the
 * corresponding fake MTD device size. This function returns zero in case of
 * success and a negative error code in case of error.
 */
static int gluebi_resized(struct ubi_volume_info *vi)
{
	struct gluebi_device *gluebi;

	mutex_lock(&devices_mutex);
	gluebi = find_gluebi_nolock(vi->ubi_num, vi->vol_id);
	if (!gluebi) {
		mutex_unlock(&devices_mutex);
		err_msg("got update notification for unknown UBI device %d "
			"volume %d", vi->ubi_num, vi->vol_id);
		return -ENOENT;
	}
	gluebi->mtd.size = vi->used_bytes;
	mutex_unlock(&devices_mutex);
	return 0;
}

/**
 * gluebi_notify - UBI notification handler.
 * @nb: registered notifier block
 * @l: notification type
 * @ptr: pointer to the &struct ubi_notification object
 */
static int gluebi_notify(struct notifier_block *nb, unsigned long l,
			 void *ns_ptr)
{
	struct ubi_notification *nt = ns_ptr;

	switch (l) {
	case UBI_VOLUME_ADDED:
		gluebi_create(&nt->di, &nt->vi);
		break;
	case UBI_VOLUME_REMOVED:
		gluebi_remove(&nt->vi);
		break;
	case UBI_VOLUME_RESIZED:
		gluebi_resized(&nt->vi);
		break;
	case UBI_VOLUME_UPDATED:
		gluebi_updated(&nt->vi);
		break;
	default:
		break;
	}
	return NOTIFY_OK;
}

static struct notifier_block gluebi_notifier = {
	.notifier_call	= gluebi_notify,
};

static int __init ubi_gluebi_init(void)
{
	return ubi_register_volume_notifier(&gluebi_notifier, 0);
}

static void __exit ubi_gluebi_exit(void)
{
	struct gluebi_device *gluebi, *g;

	list_for_each_entry_safe(gluebi, g, &gluebi_devices, list) {
		int err;
		struct mtd_info *mtd = &gluebi->mtd;

		err = mtd_device_unregister(mtd);
		if (err)
			err_msg("error %d while removing gluebi MTD device %d, "
				"UBI device %d, volume %d - ignoring", err,
				mtd->index, gluebi->ubi_num, gluebi->vol_id);
		kfree(mtd->name);
		kfree(gluebi);
	}
	ubi_unregister_volume_notifier(&gluebi_notifier);
}

module_init(ubi_gluebi_init);
module_exit(ubi_gluebi_exit);
MODULE_DESCRIPTION("MTD emulation layer over UBI volumes");
MODULE_AUTHOR("Artem Bityutskiy, Joern Engel");
MODULE_LICENSE("GPL");