blob: e6d938417ded948b498c41590fc85435db00dfec [file] [log] [blame]
Stefan Roese0a572652009-05-12 14:29:39 +02001/*
2 * MTD device concatenation layer
3 *
4 * (C) 2002 Robert Kaiser <rkaiser@sysgo.de>
5 *
6 * NAND support by Christian Gan <cgan@iders.ca>
7 *
8 * This code is GPL
9 */
10
11#include <linux/mtd/mtd.h>
Mike Frysinger7b15e2b2012-04-09 13:39:55 +000012#include <linux/compat.h>
Stefan Roese0a572652009-05-12 14:29:39 +020013#include <linux/mtd/concat.h>
14#include <ubi_uboot.h>
15
16/*
17 * Our storage structure:
18 * Subdev points to an array of pointers to struct mtd_info objects
19 * which is allocated along with this structure
20 *
21 */
22struct mtd_concat {
23 struct mtd_info mtd;
24 int num_subdev;
25 struct mtd_info **subdev;
26};
27
28/*
29 * how to calculate the size required for the above structure,
30 * including the pointer array subdev points to:
31 */
32#define SIZEOF_STRUCT_MTD_CONCAT(num_subdev) \
33 ((sizeof(struct mtd_concat) + (num_subdev) * sizeof(struct mtd_info *)))
34
35/*
36 * Given a pointer to the MTD object in the mtd_concat structure,
37 * we can retrieve the pointer to that structure with this macro.
38 */
39#define CONCAT(x) ((struct mtd_concat *)(x))
40
41/*
42 * MTD methods which look up the relevant subdevice, translate the
43 * effective address and pass through to the subdevice.
44 */
45
46static int
47concat_read(struct mtd_info *mtd, loff_t from, size_t len,
48 size_t * retlen, u_char * buf)
49{
50 struct mtd_concat *concat = CONCAT(mtd);
51 int ret = 0, err;
52 int i;
53
54 *retlen = 0;
55
56 for (i = 0; i < concat->num_subdev; i++) {
57 struct mtd_info *subdev = concat->subdev[i];
58 size_t size, retsize;
59
60 if (from >= subdev->size) {
61 /* Not destined for this subdev */
62 size = 0;
63 from -= subdev->size;
64 continue;
65 }
66 if (from + len > subdev->size)
67 /* First part goes into this subdev */
68 size = subdev->size - from;
69 else
70 /* Entire transaction goes into this subdev */
71 size = len;
72
73 err = subdev->read(subdev, from, size, &retsize, buf);
74
75 /* Save information about bitflips! */
76 if (unlikely(err)) {
77 if (err == -EBADMSG) {
78 mtd->ecc_stats.failed++;
79 ret = err;
80 } else if (err == -EUCLEAN) {
81 mtd->ecc_stats.corrected++;
82 /* Do not overwrite -EBADMSG !! */
83 if (!ret)
84 ret = err;
85 } else
86 return err;
87 }
88
89 *retlen += retsize;
90 len -= size;
91 if (len == 0)
92 return ret;
93
94 buf += size;
95 from = 0;
96 }
97 return -EINVAL;
98}
99
100static int
101concat_write(struct mtd_info *mtd, loff_t to, size_t len,
102 size_t * retlen, const u_char * buf)
103{
104 struct mtd_concat *concat = CONCAT(mtd);
105 int err = -EINVAL;
106 int i;
107
108 if (!(mtd->flags & MTD_WRITEABLE))
109 return -EROFS;
110
111 *retlen = 0;
112
113 for (i = 0; i < concat->num_subdev; i++) {
114 struct mtd_info *subdev = concat->subdev[i];
115 size_t size, retsize;
116
117 if (to >= subdev->size) {
118 size = 0;
119 to -= subdev->size;
120 continue;
121 }
122 if (to + len > subdev->size)
123 size = subdev->size - to;
124 else
125 size = len;
126
127 if (!(subdev->flags & MTD_WRITEABLE))
128 err = -EROFS;
129 else
130 err = subdev->write(subdev, to, size, &retsize, buf);
131
132 if (err)
133 break;
134
135 *retlen += retsize;
136 len -= size;
137 if (len == 0)
138 break;
139
140 err = -EINVAL;
141 buf += size;
142 to = 0;
143 }
144 return err;
145}
146
147static int
148concat_read_oob(struct mtd_info *mtd, loff_t from, struct mtd_oob_ops *ops)
149{
150 struct mtd_concat *concat = CONCAT(mtd);
151 struct mtd_oob_ops devops = *ops;
152 int i, err, ret = 0;
153
154 ops->retlen = ops->oobretlen = 0;
155
156 for (i = 0; i < concat->num_subdev; i++) {
157 struct mtd_info *subdev = concat->subdev[i];
158
159 if (from >= subdev->size) {
160 from -= subdev->size;
161 continue;
162 }
163
164 /* partial read ? */
165 if (from + devops.len > subdev->size)
166 devops.len = subdev->size - from;
167
168 err = subdev->read_oob(subdev, from, &devops);
169 ops->retlen += devops.retlen;
170 ops->oobretlen += devops.oobretlen;
171
172 /* Save information about bitflips! */
173 if (unlikely(err)) {
174 if (err == -EBADMSG) {
175 mtd->ecc_stats.failed++;
176 ret = err;
177 } else if (err == -EUCLEAN) {
178 mtd->ecc_stats.corrected++;
179 /* Do not overwrite -EBADMSG !! */
180 if (!ret)
181 ret = err;
182 } else
183 return err;
184 }
185
186 if (devops.datbuf) {
187 devops.len = ops->len - ops->retlen;
188 if (!devops.len)
189 return ret;
190 devops.datbuf += devops.retlen;
191 }
192 if (devops.oobbuf) {
193 devops.ooblen = ops->ooblen - ops->oobretlen;
194 if (!devops.ooblen)
195 return ret;
196 devops.oobbuf += ops->oobretlen;
197 }
198
199 from = 0;
200 }
201 return -EINVAL;
202}
203
204static int
205concat_write_oob(struct mtd_info *mtd, loff_t to, struct mtd_oob_ops *ops)
206{
207 struct mtd_concat *concat = CONCAT(mtd);
208 struct mtd_oob_ops devops = *ops;
209 int i, err;
210
211 if (!(mtd->flags & MTD_WRITEABLE))
212 return -EROFS;
213
214 ops->retlen = 0;
215
216 for (i = 0; i < concat->num_subdev; i++) {
217 struct mtd_info *subdev = concat->subdev[i];
218
219 if (to >= subdev->size) {
220 to -= subdev->size;
221 continue;
222 }
223
224 /* partial write ? */
225 if (to + devops.len > subdev->size)
226 devops.len = subdev->size - to;
227
228 err = subdev->write_oob(subdev, to, &devops);
229 ops->retlen += devops.retlen;
230 if (err)
231 return err;
232
233 if (devops.datbuf) {
234 devops.len = ops->len - ops->retlen;
235 if (!devops.len)
236 return 0;
237 devops.datbuf += devops.retlen;
238 }
239 if (devops.oobbuf) {
240 devops.ooblen = ops->ooblen - ops->oobretlen;
241 if (!devops.ooblen)
242 return 0;
243 devops.oobbuf += devops.oobretlen;
244 }
245 to = 0;
246 }
247 return -EINVAL;
248}
249
250static void concat_erase_callback(struct erase_info *instr)
251{
252 /* Nothing to do here in U-Boot */
253}
254
255static int concat_dev_erase(struct mtd_info *mtd, struct erase_info *erase)
256{
257 int err;
258 wait_queue_head_t waitq;
259 DECLARE_WAITQUEUE(wait, current);
260
261 /*
262 * This code was stol^H^H^H^Hinspired by mtdchar.c
263 */
264 init_waitqueue_head(&waitq);
265
266 erase->mtd = mtd;
267 erase->callback = concat_erase_callback;
268 erase->priv = (unsigned long) &waitq;
269
270 /*
271 * FIXME: Allow INTERRUPTIBLE. Which means
272 * not having the wait_queue head on the stack.
273 */
274 err = mtd->erase(mtd, erase);
275 if (!err) {
276 set_current_state(TASK_UNINTERRUPTIBLE);
277 add_wait_queue(&waitq, &wait);
278 if (erase->state != MTD_ERASE_DONE
279 && erase->state != MTD_ERASE_FAILED)
280 schedule();
281 remove_wait_queue(&waitq, &wait);
282 set_current_state(TASK_RUNNING);
283
284 err = (erase->state == MTD_ERASE_FAILED) ? -EIO : 0;
285 }
286 return err;
287}
288
289static int concat_erase(struct mtd_info *mtd, struct erase_info *instr)
290{
291 struct mtd_concat *concat = CONCAT(mtd);
292 struct mtd_info *subdev;
293 int i, err;
294 uint64_t length, offset = 0;
295 struct erase_info *erase;
296
297 if (!(mtd->flags & MTD_WRITEABLE))
298 return -EROFS;
299
300 if (instr->addr > concat->mtd.size)
301 return -EINVAL;
302
303 if (instr->len + instr->addr > concat->mtd.size)
304 return -EINVAL;
305
306 /*
307 * Check for proper erase block alignment of the to-be-erased area.
308 * It is easier to do this based on the super device's erase
309 * region info rather than looking at each particular sub-device
310 * in turn.
311 */
312 if (!concat->mtd.numeraseregions) {
313 /* the easy case: device has uniform erase block size */
314 if (instr->addr & (concat->mtd.erasesize - 1))
315 return -EINVAL;
316 if (instr->len & (concat->mtd.erasesize - 1))
317 return -EINVAL;
318 } else {
319 /* device has variable erase size */
320 struct mtd_erase_region_info *erase_regions =
321 concat->mtd.eraseregions;
322
323 /*
324 * Find the erase region where the to-be-erased area begins:
325 */
326 for (i = 0; i < concat->mtd.numeraseregions &&
327 instr->addr >= erase_regions[i].offset; i++) ;
328 --i;
329
330 /*
331 * Now erase_regions[i] is the region in which the
332 * to-be-erased area begins. Verify that the starting
333 * offset is aligned to this region's erase size:
334 */
335 if (instr->addr & (erase_regions[i].erasesize - 1))
336 return -EINVAL;
337
338 /*
339 * now find the erase region where the to-be-erased area ends:
340 */
341 for (; i < concat->mtd.numeraseregions &&
342 (instr->addr + instr->len) >= erase_regions[i].offset;
343 ++i) ;
344 --i;
345 /*
346 * check if the ending offset is aligned to this region's erase size
347 */
348 if ((instr->addr + instr->len) & (erase_regions[i].erasesize -
349 1))
350 return -EINVAL;
351 }
352
353 instr->fail_addr = MTD_FAIL_ADDR_UNKNOWN;
354
355 /* make a local copy of instr to avoid modifying the caller's struct */
356 erase = kmalloc(sizeof (struct erase_info), GFP_KERNEL);
357
358 if (!erase)
359 return -ENOMEM;
360
361 *erase = *instr;
362 length = instr->len;
363
364 /*
365 * find the subdevice where the to-be-erased area begins, adjust
366 * starting offset to be relative to the subdevice start
367 */
368 for (i = 0; i < concat->num_subdev; i++) {
369 subdev = concat->subdev[i];
370 if (subdev->size <= erase->addr) {
371 erase->addr -= subdev->size;
372 offset += subdev->size;
373 } else {
374 break;
375 }
376 }
377
378 /* must never happen since size limit has been verified above */
379 BUG_ON(i >= concat->num_subdev);
380
381 /* now do the erase: */
382 err = 0;
383 for (; length > 0; i++) {
384 /* loop for all subdevices affected by this request */
385 subdev = concat->subdev[i]; /* get current subdevice */
386
387 /* limit length to subdevice's size: */
388 if (erase->addr + length > subdev->size)
389 erase->len = subdev->size - erase->addr;
390 else
391 erase->len = length;
392
393 if (!(subdev->flags & MTD_WRITEABLE)) {
394 err = -EROFS;
395 break;
396 }
397 length -= erase->len;
398 if ((err = concat_dev_erase(subdev, erase))) {
399 /* sanity check: should never happen since
400 * block alignment has been checked above */
401 BUG_ON(err == -EINVAL);
402 if (erase->fail_addr != MTD_FAIL_ADDR_UNKNOWN)
403 instr->fail_addr = erase->fail_addr + offset;
404 break;
405 }
406 /*
407 * erase->addr specifies the offset of the area to be
408 * erased *within the current subdevice*. It can be
409 * non-zero only the first time through this loop, i.e.
410 * for the first subdevice where blocks need to be erased.
411 * All the following erases must begin at the start of the
412 * current subdevice, i.e. at offset zero.
413 */
414 erase->addr = 0;
415 offset += subdev->size;
416 }
417 instr->state = erase->state;
418 kfree(erase);
419 if (err)
420 return err;
421
422 if (instr->callback)
423 instr->callback(instr);
424 return 0;
425}
426
427static int concat_lock(struct mtd_info *mtd, loff_t ofs, uint64_t len)
428{
429 struct mtd_concat *concat = CONCAT(mtd);
430 int i, err = -EINVAL;
431
432 if ((len + ofs) > mtd->size)
433 return -EINVAL;
434
435 for (i = 0; i < concat->num_subdev; i++) {
436 struct mtd_info *subdev = concat->subdev[i];
437 uint64_t size;
438
439 if (ofs >= subdev->size) {
440 size = 0;
441 ofs -= subdev->size;
442 continue;
443 }
444 if (ofs + len > subdev->size)
445 size = subdev->size - ofs;
446 else
447 size = len;
448
449 err = subdev->lock(subdev, ofs, size);
450
451 if (err)
452 break;
453
454 len -= size;
455 if (len == 0)
456 break;
457
458 err = -EINVAL;
459 ofs = 0;
460 }
461
462 return err;
463}
464
465static int concat_unlock(struct mtd_info *mtd, loff_t ofs, uint64_t len)
466{
467 struct mtd_concat *concat = CONCAT(mtd);
468 int i, err = 0;
469
470 if ((len + ofs) > mtd->size)
471 return -EINVAL;
472
473 for (i = 0; i < concat->num_subdev; i++) {
474 struct mtd_info *subdev = concat->subdev[i];
475 uint64_t size;
476
477 if (ofs >= subdev->size) {
478 size = 0;
479 ofs -= subdev->size;
480 continue;
481 }
482 if (ofs + len > subdev->size)
483 size = subdev->size - ofs;
484 else
485 size = len;
486
487 err = subdev->unlock(subdev, ofs, size);
488
489 if (err)
490 break;
491
492 len -= size;
493 if (len == 0)
494 break;
495
496 err = -EINVAL;
497 ofs = 0;
498 }
499
500 return err;
501}
502
503static void concat_sync(struct mtd_info *mtd)
504{
505 struct mtd_concat *concat = CONCAT(mtd);
506 int i;
507
508 for (i = 0; i < concat->num_subdev; i++) {
509 struct mtd_info *subdev = concat->subdev[i];
510 subdev->sync(subdev);
511 }
512}
513
514static int concat_block_isbad(struct mtd_info *mtd, loff_t ofs)
515{
516 struct mtd_concat *concat = CONCAT(mtd);
517 int i, res = 0;
518
519 if (!concat->subdev[0]->block_isbad)
520 return res;
521
522 if (ofs > mtd->size)
523 return -EINVAL;
524
525 for (i = 0; i < concat->num_subdev; i++) {
526 struct mtd_info *subdev = concat->subdev[i];
527
528 if (ofs >= subdev->size) {
529 ofs -= subdev->size;
530 continue;
531 }
532
533 res = subdev->block_isbad(subdev, ofs);
534 break;
535 }
536
537 return res;
538}
539
540static int concat_block_markbad(struct mtd_info *mtd, loff_t ofs)
541{
542 struct mtd_concat *concat = CONCAT(mtd);
543 int i, err = -EINVAL;
544
545 if (!concat->subdev[0]->block_markbad)
546 return 0;
547
548 if (ofs > mtd->size)
549 return -EINVAL;
550
551 for (i = 0; i < concat->num_subdev; i++) {
552 struct mtd_info *subdev = concat->subdev[i];
553
554 if (ofs >= subdev->size) {
555 ofs -= subdev->size;
556 continue;
557 }
558
559 err = subdev->block_markbad(subdev, ofs);
560 if (!err)
561 mtd->ecc_stats.badblocks++;
562 break;
563 }
564
565 return err;
566}
567
568/*
569 * This function constructs a virtual MTD device by concatenating
570 * num_devs MTD devices. A pointer to the new device object is
571 * stored to *new_dev upon success. This function does _not_
572 * register any devices: this is the caller's responsibility.
573 */
574struct mtd_info *mtd_concat_create(struct mtd_info *subdev[], /* subdevices to concatenate */
575 int num_devs, /* number of subdevices */
576 const char *name)
577{ /* name for the new device */
578 int i;
579 size_t size;
580 struct mtd_concat *concat;
581 uint32_t max_erasesize, curr_erasesize;
582 int num_erase_region;
583
584 debug("Concatenating MTD devices:\n");
585 for (i = 0; i < num_devs; i++)
586 debug("(%d): \"%s\"\n", i, subdev[i]->name);
587 debug("into device \"%s\"\n", name);
588
589 /* allocate the device structure */
590 size = SIZEOF_STRUCT_MTD_CONCAT(num_devs);
591 concat = kzalloc(size, GFP_KERNEL);
592 if (!concat) {
593 printk
594 ("memory allocation error while creating concatenated device \"%s\"\n",
595 name);
596 return NULL;
597 }
598 concat->subdev = (struct mtd_info **) (concat + 1);
599
600 /*
601 * Set up the new "super" device's MTD object structure, check for
602 * incompatibilites between the subdevices.
603 */
604 concat->mtd.type = subdev[0]->type;
605 concat->mtd.flags = subdev[0]->flags;
606 concat->mtd.size = subdev[0]->size;
607 concat->mtd.erasesize = subdev[0]->erasesize;
608 concat->mtd.writesize = subdev[0]->writesize;
609 concat->mtd.subpage_sft = subdev[0]->subpage_sft;
610 concat->mtd.oobsize = subdev[0]->oobsize;
611 concat->mtd.oobavail = subdev[0]->oobavail;
612 if (subdev[0]->read_oob)
613 concat->mtd.read_oob = concat_read_oob;
614 if (subdev[0]->write_oob)
615 concat->mtd.write_oob = concat_write_oob;
616 if (subdev[0]->block_isbad)
617 concat->mtd.block_isbad = concat_block_isbad;
618 if (subdev[0]->block_markbad)
619 concat->mtd.block_markbad = concat_block_markbad;
620
621 concat->mtd.ecc_stats.badblocks = subdev[0]->ecc_stats.badblocks;
622
623 concat->subdev[0] = subdev[0];
624
625 for (i = 1; i < num_devs; i++) {
626 if (concat->mtd.type != subdev[i]->type) {
627 kfree(concat);
628 printk("Incompatible device type on \"%s\"\n",
629 subdev[i]->name);
630 return NULL;
631 }
632 if (concat->mtd.flags != subdev[i]->flags) {
633 /*
634 * Expect all flags except MTD_WRITEABLE to be
635 * equal on all subdevices.
636 */
637 if ((concat->mtd.flags ^ subdev[i]->
638 flags) & ~MTD_WRITEABLE) {
639 kfree(concat);
640 printk("Incompatible device flags on \"%s\"\n",
641 subdev[i]->name);
642 return NULL;
643 } else
644 /* if writeable attribute differs,
645 make super device writeable */
646 concat->mtd.flags |=
647 subdev[i]->flags & MTD_WRITEABLE;
648 }
649
650 concat->mtd.size += subdev[i]->size;
651 concat->mtd.ecc_stats.badblocks +=
652 subdev[i]->ecc_stats.badblocks;
653 if (concat->mtd.writesize != subdev[i]->writesize ||
654 concat->mtd.subpage_sft != subdev[i]->subpage_sft ||
655 concat->mtd.oobsize != subdev[i]->oobsize ||
656 !concat->mtd.read_oob != !subdev[i]->read_oob ||
657 !concat->mtd.write_oob != !subdev[i]->write_oob) {
658 kfree(concat);
659 printk("Incompatible OOB or ECC data on \"%s\"\n",
660 subdev[i]->name);
661 return NULL;
662 }
663 concat->subdev[i] = subdev[i];
664
665 }
666
667 concat->mtd.ecclayout = subdev[0]->ecclayout;
668
669 concat->num_subdev = num_devs;
670 concat->mtd.name = name;
671
672 concat->mtd.erase = concat_erase;
673 concat->mtd.read = concat_read;
674 concat->mtd.write = concat_write;
675 concat->mtd.sync = concat_sync;
676 concat->mtd.lock = concat_lock;
677 concat->mtd.unlock = concat_unlock;
678
679 /*
680 * Combine the erase block size info of the subdevices:
681 *
682 * first, walk the map of the new device and see how
683 * many changes in erase size we have
684 */
685 max_erasesize = curr_erasesize = subdev[0]->erasesize;
686 num_erase_region = 1;
687 for (i = 0; i < num_devs; i++) {
688 if (subdev[i]->numeraseregions == 0) {
689 /* current subdevice has uniform erase size */
690 if (subdev[i]->erasesize != curr_erasesize) {
691 /* if it differs from the last subdevice's erase size, count it */
692 ++num_erase_region;
693 curr_erasesize = subdev[i]->erasesize;
694 if (curr_erasesize > max_erasesize)
695 max_erasesize = curr_erasesize;
696 }
697 } else {
698 /* current subdevice has variable erase size */
699 int j;
700 for (j = 0; j < subdev[i]->numeraseregions; j++) {
701
702 /* walk the list of erase regions, count any changes */
703 if (subdev[i]->eraseregions[j].erasesize !=
704 curr_erasesize) {
705 ++num_erase_region;
706 curr_erasesize =
707 subdev[i]->eraseregions[j].
708 erasesize;
709 if (curr_erasesize > max_erasesize)
710 max_erasesize = curr_erasesize;
711 }
712 }
713 }
714 }
715
716 if (num_erase_region == 1) {
717 /*
718 * All subdevices have the same uniform erase size.
719 * This is easy:
720 */
721 concat->mtd.erasesize = curr_erasesize;
722 concat->mtd.numeraseregions = 0;
723 } else {
724 uint64_t tmp64;
725
726 /*
727 * erase block size varies across the subdevices: allocate
728 * space to store the data describing the variable erase regions
729 */
730 struct mtd_erase_region_info *erase_region_p;
731 uint64_t begin, position;
732
733 concat->mtd.erasesize = max_erasesize;
734 concat->mtd.numeraseregions = num_erase_region;
735 concat->mtd.eraseregions = erase_region_p =
736 kmalloc(num_erase_region *
737 sizeof (struct mtd_erase_region_info), GFP_KERNEL);
738 if (!erase_region_p) {
739 kfree(concat);
740 printk
741 ("memory allocation error while creating erase region list"
742 " for device \"%s\"\n", name);
743 return NULL;
744 }
745
746 /*
747 * walk the map of the new device once more and fill in
748 * in erase region info:
749 */
750 curr_erasesize = subdev[0]->erasesize;
751 begin = position = 0;
752 for (i = 0; i < num_devs; i++) {
753 if (subdev[i]->numeraseregions == 0) {
754 /* current subdevice has uniform erase size */
755 if (subdev[i]->erasesize != curr_erasesize) {
756 /*
757 * fill in an mtd_erase_region_info structure for the area
758 * we have walked so far:
759 */
760 erase_region_p->offset = begin;
761 erase_region_p->erasesize =
762 curr_erasesize;
763 tmp64 = position - begin;
764 do_div(tmp64, curr_erasesize);
765 erase_region_p->numblocks = tmp64;
766 begin = position;
767
768 curr_erasesize = subdev[i]->erasesize;
769 ++erase_region_p;
770 }
771 position += subdev[i]->size;
772 } else {
773 /* current subdevice has variable erase size */
774 int j;
775 for (j = 0; j < subdev[i]->numeraseregions; j++) {
776 /* walk the list of erase regions, count any changes */
777 if (subdev[i]->eraseregions[j].
778 erasesize != curr_erasesize) {
779 erase_region_p->offset = begin;
780 erase_region_p->erasesize =
781 curr_erasesize;
782 tmp64 = position - begin;
783 do_div(tmp64, curr_erasesize);
784 erase_region_p->numblocks = tmp64;
785 begin = position;
786
787 curr_erasesize =
788 subdev[i]->eraseregions[j].
789 erasesize;
790 ++erase_region_p;
791 }
792 position +=
793 subdev[i]->eraseregions[j].
794 numblocks * (uint64_t)curr_erasesize;
795 }
796 }
797 }
798 /* Now write the final entry */
799 erase_region_p->offset = begin;
800 erase_region_p->erasesize = curr_erasesize;
801 tmp64 = position - begin;
802 do_div(tmp64, curr_erasesize);
803 erase_region_p->numblocks = tmp64;
804 }
805
806 return &concat->mtd;
807}