Root/drivers/mtd/mtdconcat.c

1/*
2 * MTD device concatenation layer
3 *
4 * Copyright © 2002 Robert Kaiser <rkaiser@sysgo.de>
5 * Copyright © 2002-2010 David Woodhouse <dwmw2@infradead.org>
6 *
7 * NAND support by Christian Gan <cgan@iders.ca>
8 *
9 * This program is free software; you can redistribute it and/or modify
10 * it under the terms of the GNU General Public License as published by
11 * the Free Software Foundation; either version 2 of the License, or
12 * (at your option) any later version.
13 *
14 * This program is distributed in the hope that it will be useful,
15 * but WITHOUT ANY WARRANTY; without even the implied warranty of
16 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
17 * GNU General Public License for more details.
18 *
19 * You should have received a copy of the GNU General Public License
20 * along with this program; if not, write to the Free Software
21 * Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA
22 *
23 */
24
25#include <linux/kernel.h>
26#include <linux/module.h>
27#include <linux/slab.h>
28#include <linux/sched.h>
29#include <linux/types.h>
30#include <linux/backing-dev.h>
31
32#include <linux/mtd/mtd.h>
33#include <linux/mtd/concat.h>
34
35#include <asm/div64.h>
36
37/*
38 * Our storage structure:
39 * Subdev points to an array of pointers to struct mtd_info objects
40 * which is allocated along with this structure
41 *
42 */
43struct mtd_concat {
44    struct mtd_info mtd;
45    int num_subdev;
46    struct mtd_info **subdev;
47};
48
49/*
50 * how to calculate the size required for the above structure,
51 * including the pointer array subdev points to:
52 */
53#define SIZEOF_STRUCT_MTD_CONCAT(num_subdev) \
54    ((sizeof(struct mtd_concat) + (num_subdev) * sizeof(struct mtd_info *)))
55
56/*
57 * Given a pointer to the MTD object in the mtd_concat structure,
58 * we can retrieve the pointer to that structure with this macro.
59 */
60#define CONCAT(x) ((struct mtd_concat *)(x))
61
62/*
63 * MTD methods which look up the relevant subdevice, translate the
64 * effective address and pass through to the subdevice.
65 */
66
67static int
68concat_read(struct mtd_info *mtd, loff_t from, size_t len,
69        size_t * retlen, u_char * buf)
70{
71    struct mtd_concat *concat = CONCAT(mtd);
72    int ret = 0, err;
73    int i;
74
75    for (i = 0; i < concat->num_subdev; i++) {
76        struct mtd_info *subdev = concat->subdev[i];
77        size_t size, retsize;
78
79        if (from >= subdev->size) {
80            /* Not destined for this subdev */
81            size = 0;
82            from -= subdev->size;
83            continue;
84        }
85        if (from + len > subdev->size)
86            /* First part goes into this subdev */
87            size = subdev->size - from;
88        else
89            /* Entire transaction goes into this subdev */
90            size = len;
91
92        err = mtd_read(subdev, from, size, &retsize, buf);
93
94        /* Save information about bitflips! */
95        if (unlikely(err)) {
96            if (mtd_is_eccerr(err)) {
97                mtd->ecc_stats.failed++;
98                ret = err;
99            } else if (mtd_is_bitflip(err)) {
100                mtd->ecc_stats.corrected++;
101                /* Do not overwrite -EBADMSG !! */
102                if (!ret)
103                    ret = err;
104            } else
105                return err;
106        }
107
108        *retlen += retsize;
109        len -= size;
110        if (len == 0)
111            return ret;
112
113        buf += size;
114        from = 0;
115    }
116    return -EINVAL;
117}
118
119static int
120concat_write(struct mtd_info *mtd, loff_t to, size_t len,
121         size_t * retlen, const u_char * buf)
122{
123    struct mtd_concat *concat = CONCAT(mtd);
124    int err = -EINVAL;
125    int i;
126
127    for (i = 0; i < concat->num_subdev; i++) {
128        struct mtd_info *subdev = concat->subdev[i];
129        size_t size, retsize;
130
131        if (to >= subdev->size) {
132            size = 0;
133            to -= subdev->size;
134            continue;
135        }
136        if (to + len > subdev->size)
137            size = subdev->size - to;
138        else
139            size = len;
140
141        err = mtd_write(subdev, to, size, &retsize, buf);
142        if (err)
143            break;
144
145        *retlen += retsize;
146        len -= size;
147        if (len == 0)
148            break;
149
150        err = -EINVAL;
151        buf += size;
152        to = 0;
153    }
154    return err;
155}
156
157static int
158concat_writev(struct mtd_info *mtd, const struct kvec *vecs,
159        unsigned long count, loff_t to, size_t * retlen)
160{
161    struct mtd_concat *concat = CONCAT(mtd);
162    struct kvec *vecs_copy;
163    unsigned long entry_low, entry_high;
164    size_t total_len = 0;
165    int i;
166    int err = -EINVAL;
167
168    /* Calculate total length of data */
169    for (i = 0; i < count; i++)
170        total_len += vecs[i].iov_len;
171
172    /* Check alignment */
173    if (mtd->writesize > 1) {
174        uint64_t __to = to;
175        if (do_div(__to, mtd->writesize) || (total_len % mtd->writesize))
176            return -EINVAL;
177    }
178
179    /* make a copy of vecs */
180    vecs_copy = kmemdup(vecs, sizeof(struct kvec) * count, GFP_KERNEL);
181    if (!vecs_copy)
182        return -ENOMEM;
183
184    entry_low = 0;
185    for (i = 0; i < concat->num_subdev; i++) {
186        struct mtd_info *subdev = concat->subdev[i];
187        size_t size, wsize, retsize, old_iov_len;
188
189        if (to >= subdev->size) {
190            to -= subdev->size;
191            continue;
192        }
193
194        size = min_t(uint64_t, total_len, subdev->size - to);
195        wsize = size; /* store for future use */
196
197        entry_high = entry_low;
198        while (entry_high < count) {
199            if (size <= vecs_copy[entry_high].iov_len)
200                break;
201            size -= vecs_copy[entry_high++].iov_len;
202        }
203
204        old_iov_len = vecs_copy[entry_high].iov_len;
205        vecs_copy[entry_high].iov_len = size;
206
207        err = mtd_writev(subdev, &vecs_copy[entry_low],
208                 entry_high - entry_low + 1, to, &retsize);
209
210        vecs_copy[entry_high].iov_len = old_iov_len - size;
211        vecs_copy[entry_high].iov_base += size;
212
213        entry_low = entry_high;
214
215        if (err)
216            break;
217
218        *retlen += retsize;
219        total_len -= wsize;
220
221        if (total_len == 0)
222            break;
223
224        err = -EINVAL;
225        to = 0;
226    }
227
228    kfree(vecs_copy);
229    return err;
230}
231
232static int
233concat_read_oob(struct mtd_info *mtd, loff_t from, struct mtd_oob_ops *ops)
234{
235    struct mtd_concat *concat = CONCAT(mtd);
236    struct mtd_oob_ops devops = *ops;
237    int i, err, ret = 0;
238
239    ops->retlen = ops->oobretlen = 0;
240
241    for (i = 0; i < concat->num_subdev; i++) {
242        struct mtd_info *subdev = concat->subdev[i];
243
244        if (from >= subdev->size) {
245            from -= subdev->size;
246            continue;
247        }
248
249        /* partial read ? */
250        if (from + devops.len > subdev->size)
251            devops.len = subdev->size - from;
252
253        err = mtd_read_oob(subdev, from, &devops);
254        ops->retlen += devops.retlen;
255        ops->oobretlen += devops.oobretlen;
256
257        /* Save information about bitflips! */
258        if (unlikely(err)) {
259            if (mtd_is_eccerr(err)) {
260                mtd->ecc_stats.failed++;
261                ret = err;
262            } else if (mtd_is_bitflip(err)) {
263                mtd->ecc_stats.corrected++;
264                /* Do not overwrite -EBADMSG !! */
265                if (!ret)
266                    ret = err;
267            } else
268                return err;
269        }
270
271        if (devops.datbuf) {
272            devops.len = ops->len - ops->retlen;
273            if (!devops.len)
274                return ret;
275            devops.datbuf += devops.retlen;
276        }
277        if (devops.oobbuf) {
278            devops.ooblen = ops->ooblen - ops->oobretlen;
279            if (!devops.ooblen)
280                return ret;
281            devops.oobbuf += ops->oobretlen;
282        }
283
284        from = 0;
285    }
286    return -EINVAL;
287}
288
289static int
290concat_write_oob(struct mtd_info *mtd, loff_t to, struct mtd_oob_ops *ops)
291{
292    struct mtd_concat *concat = CONCAT(mtd);
293    struct mtd_oob_ops devops = *ops;
294    int i, err;
295
296    if (!(mtd->flags & MTD_WRITEABLE))
297        return -EROFS;
298
299    ops->retlen = ops->oobretlen = 0;
300
301    for (i = 0; i < concat->num_subdev; i++) {
302        struct mtd_info *subdev = concat->subdev[i];
303
304        if (to >= subdev->size) {
305            to -= subdev->size;
306            continue;
307        }
308
309        /* partial write ? */
310        if (to + devops.len > subdev->size)
311            devops.len = subdev->size - to;
312
313        err = mtd_write_oob(subdev, to, &devops);
314        ops->retlen += devops.oobretlen;
315        if (err)
316            return err;
317
318        if (devops.datbuf) {
319            devops.len = ops->len - ops->retlen;
320            if (!devops.len)
321                return 0;
322            devops.datbuf += devops.retlen;
323        }
324        if (devops.oobbuf) {
325            devops.ooblen = ops->ooblen - ops->oobretlen;
326            if (!devops.ooblen)
327                return 0;
328            devops.oobbuf += devops.oobretlen;
329        }
330        to = 0;
331    }
332    return -EINVAL;
333}
334
335static void concat_erase_callback(struct erase_info *instr)
336{
337    wake_up((wait_queue_head_t *) instr->priv);
338}
339
340static int concat_dev_erase(struct mtd_info *mtd, struct erase_info *erase)
341{
342    int err;
343    wait_queue_head_t waitq;
344    DECLARE_WAITQUEUE(wait, current);
345
346    /*
347     * This code was stol^H^H^H^Hinspired by mtdchar.c
348     */
349    init_waitqueue_head(&waitq);
350
351    erase->mtd = mtd;
352    erase->callback = concat_erase_callback;
353    erase->priv = (unsigned long) &waitq;
354
355    /*
356     * FIXME: Allow INTERRUPTIBLE. Which means
357     * not having the wait_queue head on the stack.
358     */
359    err = mtd_erase(mtd, erase);
360    if (!err) {
361        set_current_state(TASK_UNINTERRUPTIBLE);
362        add_wait_queue(&waitq, &wait);
363        if (erase->state != MTD_ERASE_DONE
364            && erase->state != MTD_ERASE_FAILED)
365            schedule();
366        remove_wait_queue(&waitq, &wait);
367        set_current_state(TASK_RUNNING);
368
369        err = (erase->state == MTD_ERASE_FAILED) ? -EIO : 0;
370    }
371    return err;
372}
373
374static int concat_erase(struct mtd_info *mtd, struct erase_info *instr)
375{
376    struct mtd_concat *concat = CONCAT(mtd);
377    struct mtd_info *subdev;
378    int i, err;
379    uint64_t length, offset = 0;
380    struct erase_info *erase;
381
382    /*
383     * Check for proper erase block alignment of the to-be-erased area.
384     * It is easier to do this based on the super device's erase
385     * region info rather than looking at each particular sub-device
386     * in turn.
387     */
388    if (!concat->mtd.numeraseregions) {
389        /* the easy case: device has uniform erase block size */
390        if (instr->addr & (concat->mtd.erasesize - 1))
391            return -EINVAL;
392        if (instr->len & (concat->mtd.erasesize - 1))
393            return -EINVAL;
394    } else {
395        /* device has variable erase size */
396        struct mtd_erase_region_info *erase_regions =
397            concat->mtd.eraseregions;
398
399        /*
400         * Find the erase region where the to-be-erased area begins:
401         */
402        for (i = 0; i < concat->mtd.numeraseregions &&
403             instr->addr >= erase_regions[i].offset; i++) ;
404        --i;
405
406        /*
407         * Now erase_regions[i] is the region in which the
408         * to-be-erased area begins. Verify that the starting
409         * offset is aligned to this region's erase size:
410         */
411        if (i < 0 || instr->addr & (erase_regions[i].erasesize - 1))
412            return -EINVAL;
413
414        /*
415         * now find the erase region where the to-be-erased area ends:
416         */
417        for (; i < concat->mtd.numeraseregions &&
418             (instr->addr + instr->len) >= erase_regions[i].offset;
419             ++i) ;
420        --i;
421        /*
422         * check if the ending offset is aligned to this region's erase size
423         */
424        if (i < 0 || ((instr->addr + instr->len) &
425                    (erase_regions[i].erasesize - 1)))
426            return -EINVAL;
427    }
428
429    /* make a local copy of instr to avoid modifying the caller's struct */
430    erase = kmalloc(sizeof (struct erase_info), GFP_KERNEL);
431
432    if (!erase)
433        return -ENOMEM;
434
435    *erase = *instr;
436    length = instr->len;
437
438    /*
439     * find the subdevice where the to-be-erased area begins, adjust
440     * starting offset to be relative to the subdevice start
441     */
442    for (i = 0; i < concat->num_subdev; i++) {
443        subdev = concat->subdev[i];
444        if (subdev->size <= erase->addr) {
445            erase->addr -= subdev->size;
446            offset += subdev->size;
447        } else {
448            break;
449        }
450    }
451
452    /* must never happen since size limit has been verified above */
453    BUG_ON(i >= concat->num_subdev);
454
455    /* now do the erase: */
456    err = 0;
457    for (; length > 0; i++) {
458        /* loop for all subdevices affected by this request */
459        subdev = concat->subdev[i]; /* get current subdevice */
460
461        /* limit length to subdevice's size: */
462        if (erase->addr + length > subdev->size)
463            erase->len = subdev->size - erase->addr;
464        else
465            erase->len = length;
466
467        length -= erase->len;
468        if ((err = concat_dev_erase(subdev, erase))) {
469            /* sanity check: should never happen since
470             * block alignment has been checked above */
471            BUG_ON(err == -EINVAL);
472            if (erase->fail_addr != MTD_FAIL_ADDR_UNKNOWN)
473                instr->fail_addr = erase->fail_addr + offset;
474            break;
475        }
476        /*
477         * erase->addr specifies the offset of the area to be
478         * erased *within the current subdevice*. It can be
479         * non-zero only the first time through this loop, i.e.
480         * for the first subdevice where blocks need to be erased.
481         * All the following erases must begin at the start of the
482         * current subdevice, i.e. at offset zero.
483         */
484        erase->addr = 0;
485        offset += subdev->size;
486    }
487    instr->state = erase->state;
488    kfree(erase);
489    if (err)
490        return err;
491
492    if (instr->callback)
493        instr->callback(instr);
494    return 0;
495}
496
497static int concat_lock(struct mtd_info *mtd, loff_t ofs, uint64_t len)
498{
499    struct mtd_concat *concat = CONCAT(mtd);
500    int i, err = -EINVAL;
501
502    for (i = 0; i < concat->num_subdev; i++) {
503        struct mtd_info *subdev = concat->subdev[i];
504        uint64_t size;
505
506        if (ofs >= subdev->size) {
507            size = 0;
508            ofs -= subdev->size;
509            continue;
510        }
511        if (ofs + len > subdev->size)
512            size = subdev->size - ofs;
513        else
514            size = len;
515
516        err = mtd_lock(subdev, ofs, size);
517        if (err)
518            break;
519
520        len -= size;
521        if (len == 0)
522            break;
523
524        err = -EINVAL;
525        ofs = 0;
526    }
527
528    return err;
529}
530
531static int concat_unlock(struct mtd_info *mtd, loff_t ofs, uint64_t len)
532{
533    struct mtd_concat *concat = CONCAT(mtd);
534    int i, err = 0;
535
536    for (i = 0; i < concat->num_subdev; i++) {
537        struct mtd_info *subdev = concat->subdev[i];
538        uint64_t size;
539
540        if (ofs >= subdev->size) {
541            size = 0;
542            ofs -= subdev->size;
543            continue;
544        }
545        if (ofs + len > subdev->size)
546            size = subdev->size - ofs;
547        else
548            size = len;
549
550        err = mtd_unlock(subdev, ofs, size);
551        if (err)
552            break;
553
554        len -= size;
555        if (len == 0)
556            break;
557
558        err = -EINVAL;
559        ofs = 0;
560    }
561
562    return err;
563}
564
565static void concat_sync(struct mtd_info *mtd)
566{
567    struct mtd_concat *concat = CONCAT(mtd);
568    int i;
569
570    for (i = 0; i < concat->num_subdev; i++) {
571        struct mtd_info *subdev = concat->subdev[i];
572        mtd_sync(subdev);
573    }
574}
575
576static int concat_suspend(struct mtd_info *mtd)
577{
578    struct mtd_concat *concat = CONCAT(mtd);
579    int i, rc = 0;
580
581    for (i = 0; i < concat->num_subdev; i++) {
582        struct mtd_info *subdev = concat->subdev[i];
583        if ((rc = mtd_suspend(subdev)) < 0)
584            return rc;
585    }
586    return rc;
587}
588
589static void concat_resume(struct mtd_info *mtd)
590{
591    struct mtd_concat *concat = CONCAT(mtd);
592    int i;
593
594    for (i = 0; i < concat->num_subdev; i++) {
595        struct mtd_info *subdev = concat->subdev[i];
596        mtd_resume(subdev);
597    }
598}
599
600static int concat_block_isbad(struct mtd_info *mtd, loff_t ofs)
601{
602    struct mtd_concat *concat = CONCAT(mtd);
603    int i, res = 0;
604
605    if (!mtd_can_have_bb(concat->subdev[0]))
606        return res;
607
608    for (i = 0; i < concat->num_subdev; i++) {
609        struct mtd_info *subdev = concat->subdev[i];
610
611        if (ofs >= subdev->size) {
612            ofs -= subdev->size;
613            continue;
614        }
615
616        res = mtd_block_isbad(subdev, ofs);
617        break;
618    }
619
620    return res;
621}
622
623static int concat_block_markbad(struct mtd_info *mtd, loff_t ofs)
624{
625    struct mtd_concat *concat = CONCAT(mtd);
626    int i, err = -EINVAL;
627
628    for (i = 0; i < concat->num_subdev; i++) {
629        struct mtd_info *subdev = concat->subdev[i];
630
631        if (ofs >= subdev->size) {
632            ofs -= subdev->size;
633            continue;
634        }
635
636        err = mtd_block_markbad(subdev, ofs);
637        if (!err)
638            mtd->ecc_stats.badblocks++;
639        break;
640    }
641
642    return err;
643}
644
645/*
646 * try to support NOMMU mmaps on concatenated devices
647 * - we don't support subdev spanning as we can't guarantee it'll work
648 */
649static unsigned long concat_get_unmapped_area(struct mtd_info *mtd,
650                          unsigned long len,
651                          unsigned long offset,
652                          unsigned long flags)
653{
654    struct mtd_concat *concat = CONCAT(mtd);
655    int i;
656
657    for (i = 0; i < concat->num_subdev; i++) {
658        struct mtd_info *subdev = concat->subdev[i];
659
660        if (offset >= subdev->size) {
661            offset -= subdev->size;
662            continue;
663        }
664
665        return mtd_get_unmapped_area(subdev, len, offset, flags);
666    }
667
668    return (unsigned long) -ENOSYS;
669}
670
671/*
672 * This function constructs a virtual MTD device by concatenating
673 * num_devs MTD devices. A pointer to the new device object is
674 * stored to *new_dev upon success. This function does _not_
675 * register any devices: this is the caller's responsibility.
676 */
677struct mtd_info *mtd_concat_create(struct mtd_info *subdev[], /* subdevices to concatenate */
678                   int num_devs, /* number of subdevices */
679                   const char *name)
680{ /* name for the new device */
681    int i;
682    size_t size;
683    struct mtd_concat *concat;
684    uint32_t max_erasesize, curr_erasesize;
685    int num_erase_region;
686    int max_writebufsize = 0;
687
688    printk(KERN_NOTICE "Concatenating MTD devices:\n");
689    for (i = 0; i < num_devs; i++)
690        printk(KERN_NOTICE "(%d): \"%s\"\n", i, subdev[i]->name);
691    printk(KERN_NOTICE "into device \"%s\"\n", name);
692
693    /* allocate the device structure */
694    size = SIZEOF_STRUCT_MTD_CONCAT(num_devs);
695    concat = kzalloc(size, GFP_KERNEL);
696    if (!concat) {
697        printk
698            ("memory allocation error while creating concatenated device \"%s\"\n",
699             name);
700        return NULL;
701    }
702    concat->subdev = (struct mtd_info **) (concat + 1);
703
704    /*
705     * Set up the new "super" device's MTD object structure, check for
706     * incompatibilities between the subdevices.
707     */
708    concat->mtd.type = subdev[0]->type;
709    concat->mtd.flags = subdev[0]->flags;
710    concat->mtd.size = subdev[0]->size;
711    concat->mtd.erasesize = subdev[0]->erasesize;
712    concat->mtd.writesize = subdev[0]->writesize;
713
714    for (i = 0; i < num_devs; i++)
715        if (max_writebufsize < subdev[i]->writebufsize)
716            max_writebufsize = subdev[i]->writebufsize;
717    concat->mtd.writebufsize = max_writebufsize;
718
719    concat->mtd.subpage_sft = subdev[0]->subpage_sft;
720    concat->mtd.oobsize = subdev[0]->oobsize;
721    concat->mtd.oobavail = subdev[0]->oobavail;
722    if (subdev[0]->_writev)
723        concat->mtd._writev = concat_writev;
724    if (subdev[0]->_read_oob)
725        concat->mtd._read_oob = concat_read_oob;
726    if (subdev[0]->_write_oob)
727        concat->mtd._write_oob = concat_write_oob;
728    if (subdev[0]->_block_isbad)
729        concat->mtd._block_isbad = concat_block_isbad;
730    if (subdev[0]->_block_markbad)
731        concat->mtd._block_markbad = concat_block_markbad;
732
733    concat->mtd.ecc_stats.badblocks = subdev[0]->ecc_stats.badblocks;
734
735    concat->mtd.backing_dev_info = subdev[0]->backing_dev_info;
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
764        /* only permit direct mapping if the BDIs are all the same
765         * - copy-mapping is still permitted
766         */
767        if (concat->mtd.backing_dev_info !=
768            subdev[i]->backing_dev_info)
769            concat->mtd.backing_dev_info =
770                &default_backing_dev_info;
771
772        concat->mtd.size += subdev[i]->size;
773        concat->mtd.ecc_stats.badblocks +=
774            subdev[i]->ecc_stats.badblocks;
775        if (concat->mtd.writesize != subdev[i]->writesize ||
776            concat->mtd.subpage_sft != subdev[i]->subpage_sft ||
777            concat->mtd.oobsize != subdev[i]->oobsize ||
778            !concat->mtd._read_oob != !subdev[i]->_read_oob ||
779            !concat->mtd._write_oob != !subdev[i]->_write_oob) {
780            kfree(concat);
781            printk("Incompatible OOB or ECC data on \"%s\"\n",
782                   subdev[i]->name);
783            return NULL;
784        }
785        concat->subdev[i] = subdev[i];
786
787    }
788
789    concat->mtd.ecclayout = subdev[0]->ecclayout;
790
791    concat->num_subdev = num_devs;
792    concat->mtd.name = name;
793
794    concat->mtd._erase = concat_erase;
795    concat->mtd._read = concat_read;
796    concat->mtd._write = concat_write;
797    concat->mtd._sync = concat_sync;
798    concat->mtd._lock = concat_lock;
799    concat->mtd._unlock = concat_unlock;
800    concat->mtd._suspend = concat_suspend;
801    concat->mtd._resume = concat_resume;
802    concat->mtd._get_unmapped_area = concat_get_unmapped_area;
803
804    /*
805     * Combine the erase block size info of the subdevices:
806     *
807     * first, walk the map of the new device and see how
808     * many changes in erase size we have
809     */
810    max_erasesize = curr_erasesize = subdev[0]->erasesize;
811    num_erase_region = 1;
812    for (i = 0; i < num_devs; i++) {
813        if (subdev[i]->numeraseregions == 0) {
814            /* current subdevice has uniform erase size */
815            if (subdev[i]->erasesize != curr_erasesize) {
816                /* if it differs from the last subdevice's erase size, count it */
817                ++num_erase_region;
818                curr_erasesize = subdev[i]->erasesize;
819                if (curr_erasesize > max_erasesize)
820                    max_erasesize = curr_erasesize;
821            }
822        } else {
823            /* current subdevice has variable erase size */
824            int j;
825            for (j = 0; j < subdev[i]->numeraseregions; j++) {
826
827                /* walk the list of erase regions, count any changes */
828                if (subdev[i]->eraseregions[j].erasesize !=
829                    curr_erasesize) {
830                    ++num_erase_region;
831                    curr_erasesize =
832                        subdev[i]->eraseregions[j].
833                        erasesize;
834                    if (curr_erasesize > max_erasesize)
835                        max_erasesize = curr_erasesize;
836                }
837            }
838        }
839    }
840
841    if (num_erase_region == 1) {
842        /*
843         * All subdevices have the same uniform erase size.
844         * This is easy:
845         */
846        concat->mtd.erasesize = curr_erasesize;
847        concat->mtd.numeraseregions = 0;
848    } else {
849        uint64_t tmp64;
850
851        /*
852         * erase block size varies across the subdevices: allocate
853         * space to store the data describing the variable erase regions
854         */
855        struct mtd_erase_region_info *erase_region_p;
856        uint64_t begin, position;
857
858        concat->mtd.erasesize = max_erasesize;
859        concat->mtd.numeraseregions = num_erase_region;
860        concat->mtd.eraseregions = erase_region_p =
861            kmalloc(num_erase_region *
862                sizeof (struct mtd_erase_region_info), GFP_KERNEL);
863        if (!erase_region_p) {
864            kfree(concat);
865            printk
866                ("memory allocation error while creating erase region list"
867                 " for device \"%s\"\n", name);
868            return NULL;
869        }
870
871        /*
872         * walk the map of the new device once more and fill in
873         * in erase region info:
874         */
875        curr_erasesize = subdev[0]->erasesize;
876        begin = position = 0;
877        for (i = 0; i < num_devs; i++) {
878            if (subdev[i]->numeraseregions == 0) {
879                /* current subdevice has uniform erase size */
880                if (subdev[i]->erasesize != curr_erasesize) {
881                    /*
882                     * fill in an mtd_erase_region_info structure for the area
883                     * we have walked so far:
884                     */
885                    erase_region_p->offset = begin;
886                    erase_region_p->erasesize =
887                        curr_erasesize;
888                    tmp64 = position - begin;
889                    do_div(tmp64, curr_erasesize);
890                    erase_region_p->numblocks = tmp64;
891                    begin = position;
892
893                    curr_erasesize = subdev[i]->erasesize;
894                    ++erase_region_p;
895                }
896                position += subdev[i]->size;
897            } else {
898                /* current subdevice has variable erase size */
899                int j;
900                for (j = 0; j < subdev[i]->numeraseregions; j++) {
901                    /* walk the list of erase regions, count any changes */
902                    if (subdev[i]->eraseregions[j].
903                        erasesize != curr_erasesize) {
904                        erase_region_p->offset = begin;
905                        erase_region_p->erasesize =
906                            curr_erasesize;
907                        tmp64 = position - begin;
908                        do_div(tmp64, curr_erasesize);
909                        erase_region_p->numblocks = tmp64;
910                        begin = position;
911
912                        curr_erasesize =
913                            subdev[i]->eraseregions[j].
914                            erasesize;
915                        ++erase_region_p;
916                    }
917                    position +=
918                        subdev[i]->eraseregions[j].
919                        numblocks * (uint64_t)curr_erasesize;
920                }
921            }
922        }
923        /* Now write the final entry */
924        erase_region_p->offset = begin;
925        erase_region_p->erasesize = curr_erasesize;
926        tmp64 = position - begin;
927        do_div(tmp64, curr_erasesize);
928        erase_region_p->numblocks = tmp64;
929    }
930
931    return &concat->mtd;
932}
933
934/*
935 * This function destroys an MTD object obtained from concat_mtd_devs()
936 */
937
938void mtd_concat_destroy(struct mtd_info *mtd)
939{
940    struct mtd_concat *concat = CONCAT(mtd);
941    if (concat->mtd.numeraseregions)
942        kfree(concat->mtd.eraseregions);
943    kfree(concat);
944}
945
946EXPORT_SYMBOL(mtd_concat_create);
947EXPORT_SYMBOL(mtd_concat_destroy);
948
949MODULE_LICENSE("GPL");
950MODULE_AUTHOR("Robert Kaiser <rkaiser@sysgo.de>");
951MODULE_DESCRIPTION("Generic support for concatenating of MTD devices");
952

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