[PATCH] hdaps: support Lenovo ThinkPad T60
[linux-2.6] / drivers / mtd / mtdconcat.c
1 /*
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  * $Id: mtdconcat.c,v 1.11 2005/11/07 11:14:20 gleixner Exp $
11  */
12
13 #include <linux/kernel.h>
14 #include <linux/module.h>
15 #include <linux/slab.h>
16 #include <linux/sched.h>
17 #include <linux/types.h>
18
19 #include <linux/mtd/mtd.h>
20 #include <linux/mtd/concat.h>
21
22 #include <asm/div64.h>
23
24 /*
25  * Our storage structure:
26  * Subdev points to an array of pointers to struct mtd_info objects
27  * which is allocated along with this structure
28  *
29  */
30 struct mtd_concat {
31         struct mtd_info mtd;
32         int num_subdev;
33         struct mtd_info **subdev;
34 };
35
36 /*
37  * how to calculate the size required for the above structure,
38  * including the pointer array subdev points to:
39  */
40 #define SIZEOF_STRUCT_MTD_CONCAT(num_subdev)    \
41         ((sizeof(struct mtd_concat) + (num_subdev) * sizeof(struct mtd_info *)))
42
43 /*
44  * Given a pointer to the MTD object in the mtd_concat structure,
45  * we can retrieve the pointer to that structure with this macro.
46  */
47 #define CONCAT(x)  ((struct mtd_concat *)(x))
48
49 /*
50  * MTD methods which look up the relevant subdevice, translate the
51  * effective address and pass through to the subdevice.
52  */
53
54 static int
55 concat_read(struct mtd_info *mtd, loff_t from, size_t len,
56             size_t * retlen, u_char * buf)
57 {
58         struct mtd_concat *concat = CONCAT(mtd);
59         int ret = 0, err;
60         int i;
61
62         *retlen = 0;
63
64         for (i = 0; i < concat->num_subdev; i++) {
65                 struct mtd_info *subdev = concat->subdev[i];
66                 size_t size, retsize;
67
68                 if (from >= subdev->size) {
69                         /* Not destined for this subdev */
70                         size = 0;
71                         from -= subdev->size;
72                         continue;
73                 }
74                 if (from + len > subdev->size)
75                         /* First part goes into this subdev */
76                         size = subdev->size - from;
77                 else
78                         /* Entire transaction goes into this subdev */
79                         size = len;
80
81                 err = subdev->read(subdev, from, size, &retsize, buf);
82
83                 /* Save information about bitflips! */
84                 if (unlikely(err)) {
85                         if (err == -EBADMSG) {
86                                 mtd->ecc_stats.failed++;
87                                 ret = err;
88                         } else if (err == -EUCLEAN) {
89                                 mtd->ecc_stats.corrected++;
90                                 /* Do not overwrite -EBADMSG !! */
91                                 if (!ret)
92                                         ret = err;
93                         } else
94                                 return err;
95                 }
96
97                 *retlen += retsize;
98                 len -= size;
99                 if (len == 0)
100                         return ret;
101
102                 buf += size;
103                 from = 0;
104         }
105         return -EINVAL;
106 }
107
108 static int
109 concat_write(struct mtd_info *mtd, loff_t to, size_t len,
110              size_t * retlen, const u_char * buf)
111 {
112         struct mtd_concat *concat = CONCAT(mtd);
113         int err = -EINVAL;
114         int i;
115
116         if (!(mtd->flags & MTD_WRITEABLE))
117                 return -EROFS;
118
119         *retlen = 0;
120
121         for (i = 0; i < concat->num_subdev; i++) {
122                 struct mtd_info *subdev = concat->subdev[i];
123                 size_t size, retsize;
124
125                 if (to >= subdev->size) {
126                         size = 0;
127                         to -= subdev->size;
128                         continue;
129                 }
130                 if (to + len > subdev->size)
131                         size = subdev->size - to;
132                 else
133                         size = len;
134
135                 if (!(subdev->flags & MTD_WRITEABLE))
136                         err = -EROFS;
137                 else
138                         err = subdev->write(subdev, to, size, &retsize, buf);
139
140                 if (err)
141                         break;
142
143                 *retlen += retsize;
144                 len -= size;
145                 if (len == 0)
146                         break;
147
148                 err = -EINVAL;
149                 buf += size;
150                 to = 0;
151         }
152         return err;
153 }
154
155 static int
156 concat_writev(struct mtd_info *mtd, const struct kvec *vecs,
157                 unsigned long count, loff_t to, size_t * retlen)
158 {
159         struct mtd_concat *concat = CONCAT(mtd);
160         struct kvec *vecs_copy;
161         unsigned long entry_low, entry_high;
162         size_t total_len = 0;
163         int i;
164         int err = -EINVAL;
165
166         if (!(mtd->flags & MTD_WRITEABLE))
167                 return -EROFS;
168
169         *retlen = 0;
170
171         /* Calculate total length of data */
172         for (i = 0; i < count; i++)
173                 total_len += vecs[i].iov_len;
174
175         /* Do not allow write past end of device */
176         if ((to + total_len) > mtd->size)
177                 return -EINVAL;
178
179         /* Check alignment */
180         if (mtd->writesize > 1) {
181                 loff_t __to = to;
182                 if (do_div(__to, mtd->writesize) || (total_len % mtd->writesize))
183                         return -EINVAL;
184         }
185
186         /* make a copy of vecs */
187         vecs_copy = kmalloc(sizeof(struct kvec) * count, GFP_KERNEL);
188         if (!vecs_copy)
189                 return -ENOMEM;
190         memcpy(vecs_copy, vecs, sizeof(struct kvec) * count);
191
192         entry_low = 0;
193         for (i = 0; i < concat->num_subdev; i++) {
194                 struct mtd_info *subdev = concat->subdev[i];
195                 size_t size, wsize, retsize, old_iov_len;
196
197                 if (to >= subdev->size) {
198                         to -= subdev->size;
199                         continue;
200                 }
201
202                 size = min(total_len, (size_t)(subdev->size - to));
203                 wsize = size; /* store for future use */
204
205                 entry_high = entry_low;
206                 while (entry_high < count) {
207                         if (size <= vecs_copy[entry_high].iov_len)
208                                 break;
209                         size -= vecs_copy[entry_high++].iov_len;
210                 }
211
212                 old_iov_len = vecs_copy[entry_high].iov_len;
213                 vecs_copy[entry_high].iov_len = size;
214
215                 if (!(subdev->flags & MTD_WRITEABLE))
216                         err = -EROFS;
217                 else
218                         err = subdev->writev(subdev, &vecs_copy[entry_low],
219                                 entry_high - entry_low + 1, to, &retsize);
220
221                 vecs_copy[entry_high].iov_len = old_iov_len - size;
222                 vecs_copy[entry_high].iov_base += size;
223
224                 entry_low = entry_high;
225
226                 if (err)
227                         break;
228
229                 *retlen += retsize;
230                 total_len -= wsize;
231
232                 if (total_len == 0)
233                         break;
234
235                 err = -EINVAL;
236                 to = 0;
237         }
238
239         kfree(vecs_copy);
240         return err;
241 }
242
243 static int
244 concat_read_oob(struct mtd_info *mtd, loff_t from, struct mtd_oob_ops *ops)
245 {
246         struct mtd_concat *concat = CONCAT(mtd);
247         struct mtd_oob_ops devops = *ops;
248         int i, err, ret = 0;
249
250         ops->retlen = 0;
251
252         for (i = 0; i < concat->num_subdev; i++) {
253                 struct mtd_info *subdev = concat->subdev[i];
254
255                 if (from >= subdev->size) {
256                         from -= subdev->size;
257                         continue;
258                 }
259
260                 /* partial read ? */
261                 if (from + devops.len > subdev->size)
262                         devops.len = subdev->size - from;
263
264                 err = subdev->read_oob(subdev, from, &devops);
265                 ops->retlen += devops.retlen;
266
267                 /* Save information about bitflips! */
268                 if (unlikely(err)) {
269                         if (err == -EBADMSG) {
270                                 mtd->ecc_stats.failed++;
271                                 ret = err;
272                         } else if (err == -EUCLEAN) {
273                                 mtd->ecc_stats.corrected++;
274                                 /* Do not overwrite -EBADMSG !! */
275                                 if (!ret)
276                                         ret = err;
277                         } else
278                                 return err;
279                 }
280
281                 devops.len = ops->len - ops->retlen;
282                 if (!devops.len)
283                         return ret;
284
285                 if (devops.datbuf)
286                         devops.datbuf += devops.retlen;
287                 if (devops.oobbuf)
288                         devops.oobbuf += devops.ooblen;
289
290                 from = 0;
291         }
292         return -EINVAL;
293 }
294
295 static int
296 concat_write_oob(struct mtd_info *mtd, loff_t to, struct mtd_oob_ops *ops)
297 {
298         struct mtd_concat *concat = CONCAT(mtd);
299         struct mtd_oob_ops devops = *ops;
300         int i, err;
301
302         if (!(mtd->flags & MTD_WRITEABLE))
303                 return -EROFS;
304
305         ops->retlen = 0;
306
307         for (i = 0; i < concat->num_subdev; i++) {
308                 struct mtd_info *subdev = concat->subdev[i];
309
310                 if (to >= subdev->size) {
311                         to -= subdev->size;
312                         continue;
313                 }
314
315                 /* partial write ? */
316                 if (to + devops.len > subdev->size)
317                         devops.len = subdev->size - to;
318
319                 err = subdev->write_oob(subdev, to, &devops);
320                 ops->retlen += devops.retlen;
321                 if (err)
322                         return err;
323
324                 devops.len = ops->len - ops->retlen;
325                 if (!devops.len)
326                         return 0;
327
328                 if (devops.datbuf)
329                         devops.datbuf += devops.retlen;
330                 if (devops.oobbuf)
331                         devops.oobbuf += devops.ooblen;
332                 to = 0;
333         }
334         return -EINVAL;
335 }
336
337 static void concat_erase_callback(struct erase_info *instr)
338 {
339         wake_up((wait_queue_head_t *) instr->priv);
340 }
341
342 static int concat_dev_erase(struct mtd_info *mtd, struct erase_info *erase)
343 {
344         int err;
345         wait_queue_head_t waitq;
346         DECLARE_WAITQUEUE(wait, current);
347
348         /*
349          * This code was stol^H^H^H^Hinspired by mtdchar.c
350          */
351         init_waitqueue_head(&waitq);
352
353         erase->mtd = mtd;
354         erase->callback = concat_erase_callback;
355         erase->priv = (unsigned long) &waitq;
356
357         /*
358          * FIXME: Allow INTERRUPTIBLE. Which means
359          * not having the wait_queue head on the stack.
360          */
361         err = mtd->erase(mtd, erase);
362         if (!err) {
363                 set_current_state(TASK_UNINTERRUPTIBLE);
364                 add_wait_queue(&waitq, &wait);
365                 if (erase->state != MTD_ERASE_DONE
366                     && erase->state != MTD_ERASE_FAILED)
367                         schedule();
368                 remove_wait_queue(&waitq, &wait);
369                 set_current_state(TASK_RUNNING);
370
371                 err = (erase->state == MTD_ERASE_FAILED) ? -EIO : 0;
372         }
373         return err;
374 }
375
376 static int concat_erase(struct mtd_info *mtd, struct erase_info *instr)
377 {
378         struct mtd_concat *concat = CONCAT(mtd);
379         struct mtd_info *subdev;
380         int i, err;
381         u_int32_t length, offset = 0;
382         struct erase_info *erase;
383
384         if (!(mtd->flags & MTD_WRITEABLE))
385                 return -EROFS;
386
387         if (instr->addr > concat->mtd.size)
388                 return -EINVAL;
389
390         if (instr->len + instr->addr > concat->mtd.size)
391                 return -EINVAL;
392
393         /*
394          * Check for proper erase block alignment of the to-be-erased area.
395          * It is easier to do this based on the super device's erase
396          * region info rather than looking at each particular sub-device
397          * in turn.
398          */
399         if (!concat->mtd.numeraseregions) {
400                 /* the easy case: device has uniform erase block size */
401                 if (instr->addr & (concat->mtd.erasesize - 1))
402                         return -EINVAL;
403                 if (instr->len & (concat->mtd.erasesize - 1))
404                         return -EINVAL;
405         } else {
406                 /* device has variable erase size */
407                 struct mtd_erase_region_info *erase_regions =
408                     concat->mtd.eraseregions;
409
410                 /*
411                  * Find the erase region where the to-be-erased area begins:
412                  */
413                 for (i = 0; i < concat->mtd.numeraseregions &&
414                      instr->addr >= erase_regions[i].offset; i++) ;
415                 --i;
416
417                 /*
418                  * Now erase_regions[i] is the region in which the
419                  * to-be-erased area begins. Verify that the starting
420                  * offset is aligned to this region's erase size:
421                  */
422                 if (instr->addr & (erase_regions[i].erasesize - 1))
423                         return -EINVAL;
424
425                 /*
426                  * now find the erase region where the to-be-erased area ends:
427                  */
428                 for (; i < concat->mtd.numeraseregions &&
429                      (instr->addr + instr->len) >= erase_regions[i].offset;
430                      ++i) ;
431                 --i;
432                 /*
433                  * check if the ending offset is aligned to this region's erase size
434                  */
435                 if ((instr->addr + instr->len) & (erase_regions[i].erasesize -
436                                                   1))
437                         return -EINVAL;
438         }
439
440         instr->fail_addr = 0xffffffff;
441
442         /* make a local copy of instr to avoid modifying the caller's struct */
443         erase = kmalloc(sizeof (struct erase_info), GFP_KERNEL);
444
445         if (!erase)
446                 return -ENOMEM;
447
448         *erase = *instr;
449         length = instr->len;
450
451         /*
452          * find the subdevice where the to-be-erased area begins, adjust
453          * starting offset to be relative to the subdevice start
454          */
455         for (i = 0; i < concat->num_subdev; i++) {
456                 subdev = concat->subdev[i];
457                 if (subdev->size <= erase->addr) {
458                         erase->addr -= subdev->size;
459                         offset += subdev->size;
460                 } else {
461                         break;
462                 }
463         }
464
465         /* must never happen since size limit has been verified above */
466         BUG_ON(i >= concat->num_subdev);
467
468         /* now do the erase: */
469         err = 0;
470         for (; length > 0; i++) {
471                 /* loop for all subdevices affected by this request */
472                 subdev = concat->subdev[i];     /* get current subdevice */
473
474                 /* limit length to subdevice's size: */
475                 if (erase->addr + length > subdev->size)
476                         erase->len = subdev->size - erase->addr;
477                 else
478                         erase->len = length;
479
480                 if (!(subdev->flags & MTD_WRITEABLE)) {
481                         err = -EROFS;
482                         break;
483                 }
484                 length -= erase->len;
485                 if ((err = concat_dev_erase(subdev, erase))) {
486                         /* sanity check: should never happen since
487                          * block alignment has been checked above */
488                         BUG_ON(err == -EINVAL);
489                         if (erase->fail_addr != 0xffffffff)
490                                 instr->fail_addr = erase->fail_addr + offset;
491                         break;
492                 }
493                 /*
494                  * erase->addr specifies the offset of the area to be
495                  * erased *within the current subdevice*. It can be
496                  * non-zero only the first time through this loop, i.e.
497                  * for the first subdevice where blocks need to be erased.
498                  * All the following erases must begin at the start of the
499                  * current subdevice, i.e. at offset zero.
500                  */
501                 erase->addr = 0;
502                 offset += subdev->size;
503         }
504         instr->state = erase->state;
505         kfree(erase);
506         if (err)
507                 return err;
508
509         if (instr->callback)
510                 instr->callback(instr);
511         return 0;
512 }
513
514 static int concat_lock(struct mtd_info *mtd, loff_t ofs, size_t len)
515 {
516         struct mtd_concat *concat = CONCAT(mtd);
517         int i, err = -EINVAL;
518
519         if ((len + ofs) > mtd->size)
520                 return -EINVAL;
521
522         for (i = 0; i < concat->num_subdev; i++) {
523                 struct mtd_info *subdev = concat->subdev[i];
524                 size_t size;
525
526                 if (ofs >= subdev->size) {
527                         size = 0;
528                         ofs -= subdev->size;
529                         continue;
530                 }
531                 if (ofs + len > subdev->size)
532                         size = subdev->size - ofs;
533                 else
534                         size = len;
535
536                 err = subdev->lock(subdev, ofs, size);
537
538                 if (err)
539                         break;
540
541                 len -= size;
542                 if (len == 0)
543                         break;
544
545                 err = -EINVAL;
546                 ofs = 0;
547         }
548
549         return err;
550 }
551
552 static int concat_unlock(struct mtd_info *mtd, loff_t ofs, size_t len)
553 {
554         struct mtd_concat *concat = CONCAT(mtd);
555         int i, err = 0;
556
557         if ((len + ofs) > mtd->size)
558                 return -EINVAL;
559
560         for (i = 0; i < concat->num_subdev; i++) {
561                 struct mtd_info *subdev = concat->subdev[i];
562                 size_t size;
563
564                 if (ofs >= subdev->size) {
565                         size = 0;
566                         ofs -= subdev->size;
567                         continue;
568                 }
569                 if (ofs + len > subdev->size)
570                         size = subdev->size - ofs;
571                 else
572                         size = len;
573
574                 err = subdev->unlock(subdev, ofs, size);
575
576                 if (err)
577                         break;
578
579                 len -= size;
580                 if (len == 0)
581                         break;
582
583                 err = -EINVAL;
584                 ofs = 0;
585         }
586
587         return err;
588 }
589
590 static void concat_sync(struct mtd_info *mtd)
591 {
592         struct mtd_concat *concat = CONCAT(mtd);
593         int i;
594
595         for (i = 0; i < concat->num_subdev; i++) {
596                 struct mtd_info *subdev = concat->subdev[i];
597                 subdev->sync(subdev);
598         }
599 }
600
601 static int concat_suspend(struct mtd_info *mtd)
602 {
603         struct mtd_concat *concat = CONCAT(mtd);
604         int i, rc = 0;
605
606         for (i = 0; i < concat->num_subdev; i++) {
607                 struct mtd_info *subdev = concat->subdev[i];
608                 if ((rc = subdev->suspend(subdev)) < 0)
609                         return rc;
610         }
611         return rc;
612 }
613
614 static void concat_resume(struct mtd_info *mtd)
615 {
616         struct mtd_concat *concat = CONCAT(mtd);
617         int i;
618
619         for (i = 0; i < concat->num_subdev; i++) {
620                 struct mtd_info *subdev = concat->subdev[i];
621                 subdev->resume(subdev);
622         }
623 }
624
625 static int concat_block_isbad(struct mtd_info *mtd, loff_t ofs)
626 {
627         struct mtd_concat *concat = CONCAT(mtd);
628         int i, res = 0;
629
630         if (!concat->subdev[0]->block_isbad)
631                 return res;
632
633         if (ofs > mtd->size)
634                 return -EINVAL;
635
636         for (i = 0; i < concat->num_subdev; i++) {
637                 struct mtd_info *subdev = concat->subdev[i];
638
639                 if (ofs >= subdev->size) {
640                         ofs -= subdev->size;
641                         continue;
642                 }
643
644                 res = subdev->block_isbad(subdev, ofs);
645                 break;
646         }
647
648         return res;
649 }
650
651 static int concat_block_markbad(struct mtd_info *mtd, loff_t ofs)
652 {
653         struct mtd_concat *concat = CONCAT(mtd);
654         int i, err = -EINVAL;
655
656         if (!concat->subdev[0]->block_markbad)
657                 return 0;
658
659         if (ofs > mtd->size)
660                 return -EINVAL;
661
662         for (i = 0; i < concat->num_subdev; i++) {
663                 struct mtd_info *subdev = concat->subdev[i];
664
665                 if (ofs >= subdev->size) {
666                         ofs -= subdev->size;
667                         continue;
668                 }
669
670                 err = subdev->block_markbad(subdev, ofs);
671                 if (!err)
672                         mtd->ecc_stats.badblocks++;
673                 break;
674         }
675
676         return err;
677 }
678
679 /*
680  * This function constructs a virtual MTD device by concatenating
681  * num_devs MTD devices. A pointer to the new device object is
682  * stored to *new_dev upon success. This function does _not_
683  * register any devices: this is the caller's responsibility.
684  */
685 struct mtd_info *mtd_concat_create(struct mtd_info *subdev[],   /* subdevices to concatenate */
686                                    int num_devs,        /* number of subdevices      */
687                                    char *name)
688 {                               /* name for the new device   */
689         int i;
690         size_t size;
691         struct mtd_concat *concat;
692         u_int32_t max_erasesize, curr_erasesize;
693         int num_erase_region;
694
695         printk(KERN_NOTICE "Concatenating MTD devices:\n");
696         for (i = 0; i < num_devs; i++)
697                 printk(KERN_NOTICE "(%d): \"%s\"\n", i, subdev[i]->name);
698         printk(KERN_NOTICE "into device \"%s\"\n", name);
699
700         /* allocate the device structure */
701         size = SIZEOF_STRUCT_MTD_CONCAT(num_devs);
702         concat = kmalloc(size, GFP_KERNEL);
703         if (!concat) {
704                 printk
705                     ("memory allocation error while creating concatenated device \"%s\"\n",
706                      name);
707                 return NULL;
708         }
709         memset(concat, 0, size);
710         concat->subdev = (struct mtd_info **) (concat + 1);
711
712         /*
713          * Set up the new "super" device's MTD object structure, check for
714          * incompatibilites between the subdevices.
715          */
716         concat->mtd.type = subdev[0]->type;
717         concat->mtd.flags = subdev[0]->flags;
718         concat->mtd.size = subdev[0]->size;
719         concat->mtd.erasesize = subdev[0]->erasesize;
720         concat->mtd.writesize = subdev[0]->writesize;
721         concat->mtd.oobsize = subdev[0]->oobsize;
722         concat->mtd.ecctype = subdev[0]->ecctype;
723         concat->mtd.eccsize = subdev[0]->eccsize;
724         if (subdev[0]->writev)
725                 concat->mtd.writev = concat_writev;
726         if (subdev[0]->read_oob)
727                 concat->mtd.read_oob = concat_read_oob;
728         if (subdev[0]->write_oob)
729                 concat->mtd.write_oob = concat_write_oob;
730         if (subdev[0]->block_isbad)
731                 concat->mtd.block_isbad = concat_block_isbad;
732         if (subdev[0]->block_markbad)
733                 concat->mtd.block_markbad = concat_block_markbad;
734
735         concat->mtd.ecc_stats.badblocks = subdev[0]->ecc_stats.badblocks;
736
737         concat->subdev[0] = subdev[0];
738
739         for (i = 1; i < num_devs; i++) {
740                 if (concat->mtd.type != subdev[i]->type) {
741                         kfree(concat);
742                         printk("Incompatible device type on \"%s\"\n",
743                                subdev[i]->name);
744                         return NULL;
745                 }
746                 if (concat->mtd.flags != subdev[i]->flags) {
747                         /*
748                          * Expect all flags except MTD_WRITEABLE to be
749                          * equal on all subdevices.
750                          */
751                         if ((concat->mtd.flags ^ subdev[i]->
752                              flags) & ~MTD_WRITEABLE) {
753                                 kfree(concat);
754                                 printk("Incompatible device flags on \"%s\"\n",
755                                        subdev[i]->name);
756                                 return NULL;
757                         } else
758                                 /* if writeable attribute differs,
759                                    make super device writeable */
760                                 concat->mtd.flags |=
761                                     subdev[i]->flags & MTD_WRITEABLE;
762                 }
763                 concat->mtd.size += subdev[i]->size;
764                 concat->mtd.ecc_stats.badblocks +=
765                         subdev[i]->ecc_stats.badblocks;
766                 if (concat->mtd.writesize   !=  subdev[i]->writesize ||
767                     concat->mtd.oobsize    !=  subdev[i]->oobsize ||
768                     concat->mtd.ecctype    !=  subdev[i]->ecctype ||
769                     concat->mtd.eccsize    !=  subdev[i]->eccsize ||
770                     !concat->mtd.read_oob  != !subdev[i]->read_oob ||
771                     !concat->mtd.write_oob != !subdev[i]->write_oob) {
772                         kfree(concat);
773                         printk("Incompatible OOB or ECC data on \"%s\"\n",
774                                subdev[i]->name);
775                         return NULL;
776                 }
777                 concat->subdev[i] = subdev[i];
778
779         }
780
781         concat->mtd.ecclayout = subdev[0]->ecclayout;
782
783         concat->num_subdev = num_devs;
784         concat->mtd.name = name;
785
786         concat->mtd.erase = concat_erase;
787         concat->mtd.read = concat_read;
788         concat->mtd.write = concat_write;
789         concat->mtd.sync = concat_sync;
790         concat->mtd.lock = concat_lock;
791         concat->mtd.unlock = concat_unlock;
792         concat->mtd.suspend = concat_suspend;
793         concat->mtd.resume = concat_resume;
794
795         /*
796          * Combine the erase block size info of the subdevices:
797          *
798          * first, walk the map of the new device and see how
799          * many changes in erase size we have
800          */
801         max_erasesize = curr_erasesize = subdev[0]->erasesize;
802         num_erase_region = 1;
803         for (i = 0; i < num_devs; i++) {
804                 if (subdev[i]->numeraseregions == 0) {
805                         /* current subdevice has uniform erase size */
806                         if (subdev[i]->erasesize != curr_erasesize) {
807                                 /* if it differs from the last subdevice's erase size, count it */
808                                 ++num_erase_region;
809                                 curr_erasesize = subdev[i]->erasesize;
810                                 if (curr_erasesize > max_erasesize)
811                                         max_erasesize = curr_erasesize;
812                         }
813                 } else {
814                         /* current subdevice has variable erase size */
815                         int j;
816                         for (j = 0; j < subdev[i]->numeraseregions; j++) {
817
818                                 /* walk the list of erase regions, count any changes */
819                                 if (subdev[i]->eraseregions[j].erasesize !=
820                                     curr_erasesize) {
821                                         ++num_erase_region;
822                                         curr_erasesize =
823                                             subdev[i]->eraseregions[j].
824                                             erasesize;
825                                         if (curr_erasesize > max_erasesize)
826                                                 max_erasesize = curr_erasesize;
827                                 }
828                         }
829                 }
830         }
831
832         if (num_erase_region == 1) {
833                 /*
834                  * All subdevices have the same uniform erase size.
835                  * This is easy:
836                  */
837                 concat->mtd.erasesize = curr_erasesize;
838                 concat->mtd.numeraseregions = 0;
839         } else {
840                 /*
841                  * erase block size varies across the subdevices: allocate
842                  * space to store the data describing the variable erase regions
843                  */
844                 struct mtd_erase_region_info *erase_region_p;
845                 u_int32_t begin, position;
846
847                 concat->mtd.erasesize = max_erasesize;
848                 concat->mtd.numeraseregions = num_erase_region;
849                 concat->mtd.eraseregions = erase_region_p =
850                     kmalloc(num_erase_region *
851                             sizeof (struct mtd_erase_region_info), GFP_KERNEL);
852                 if (!erase_region_p) {
853                         kfree(concat);
854                         printk
855                             ("memory allocation error while creating erase region list"
856                              " for device \"%s\"\n", name);
857                         return NULL;
858                 }
859
860                 /*
861                  * walk the map of the new device once more and fill in
862                  * in erase region info:
863                  */
864                 curr_erasesize = subdev[0]->erasesize;
865                 begin = position = 0;
866                 for (i = 0; i < num_devs; i++) {
867                         if (subdev[i]->numeraseregions == 0) {
868                                 /* current subdevice has uniform erase size */
869                                 if (subdev[i]->erasesize != curr_erasesize) {
870                                         /*
871                                          *  fill in an mtd_erase_region_info structure for the area
872                                          *  we have walked so far:
873                                          */
874                                         erase_region_p->offset = begin;
875                                         erase_region_p->erasesize =
876                                             curr_erasesize;
877                                         erase_region_p->numblocks =
878                                             (position - begin) / curr_erasesize;
879                                         begin = position;
880
881                                         curr_erasesize = subdev[i]->erasesize;
882                                         ++erase_region_p;
883                                 }
884                                 position += subdev[i]->size;
885                         } else {
886                                 /* current subdevice has variable erase size */
887                                 int j;
888                                 for (j = 0; j < subdev[i]->numeraseregions; j++) {
889                                         /* walk the list of erase regions, count any changes */
890                                         if (subdev[i]->eraseregions[j].
891                                             erasesize != curr_erasesize) {
892                                                 erase_region_p->offset = begin;
893                                                 erase_region_p->erasesize =
894                                                     curr_erasesize;
895                                                 erase_region_p->numblocks =
896                                                     (position -
897                                                      begin) / curr_erasesize;
898                                                 begin = position;
899
900                                                 curr_erasesize =
901                                                     subdev[i]->eraseregions[j].
902                                                     erasesize;
903                                                 ++erase_region_p;
904                                         }
905                                         position +=
906                                             subdev[i]->eraseregions[j].
907                                             numblocks * curr_erasesize;
908                                 }
909                         }
910                 }
911                 /* Now write the final entry */
912                 erase_region_p->offset = begin;
913                 erase_region_p->erasesize = curr_erasesize;
914                 erase_region_p->numblocks = (position - begin) / curr_erasesize;
915         }
916
917         return &concat->mtd;
918 }
919
920 /*
921  * This function destroys an MTD object obtained from concat_mtd_devs()
922  */
923
924 void mtd_concat_destroy(struct mtd_info *mtd)
925 {
926         struct mtd_concat *concat = CONCAT(mtd);
927         if (concat->mtd.numeraseregions)
928                 kfree(concat->mtd.eraseregions);
929         kfree(concat);
930 }
931
932 EXPORT_SYMBOL(mtd_concat_create);
933 EXPORT_SYMBOL(mtd_concat_destroy);
934
935 MODULE_LICENSE("GPL");
936 MODULE_AUTHOR("Robert Kaiser <rkaiser@sysgo.de>");
937 MODULE_DESCRIPTION("Generic support for concatenating of MTD devices");