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[karo-tx-linux.git] / drivers / mtd / mtd_blkdevs.c
1 /*
2  * Interface to Linux block layer for MTD 'translation layers'.
3  *
4  * Copyright © 2003-2010 David Woodhouse <dwmw2@infradead.org>
5  *
6  * This program is free software; you can redistribute it and/or modify
7  * it under the terms of the GNU General Public License as published by
8  * the Free Software Foundation; either version 2 of the License, or
9  * (at your option) any later version.
10  *
11  * This program is distributed in the hope that it will be useful,
12  * but WITHOUT ANY WARRANTY; without even the implied warranty of
13  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
14  * GNU General Public License for more details.
15  *
16  * You should have received a copy of the GNU General Public License
17  * along with this program; if not, write to the Free Software
18  * Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA  02110-1301  USA
19  *
20  */
21
22 #include <linux/kernel.h>
23 #include <linux/slab.h>
24 #include <linux/module.h>
25 #include <linux/list.h>
26 #include <linux/fs.h>
27 #include <linux/mtd/blktrans.h>
28 #include <linux/mtd/mtd.h>
29 #include <linux/blkdev.h>
30 #include <linux/blkpg.h>
31 #include <linux/spinlock.h>
32 #include <linux/hdreg.h>
33 #include <linux/mutex.h>
34 #include <linux/uaccess.h>
35
36 #include "mtdcore.h"
37
38 static LIST_HEAD(blktrans_majors);
39 static DEFINE_MUTEX(blktrans_ref_mutex);
40
41 static void blktrans_dev_release(struct kref *kref)
42 {
43         struct mtd_blktrans_dev *dev =
44                 container_of(kref, struct mtd_blktrans_dev, ref);
45
46         dev->disk->private_data = NULL;
47         blk_cleanup_queue(dev->rq);
48         put_disk(dev->disk);
49         list_del(&dev->list);
50         kfree(dev);
51 }
52
53 static struct mtd_blktrans_dev *blktrans_dev_get(struct gendisk *disk)
54 {
55         struct mtd_blktrans_dev *dev;
56
57         mutex_lock(&blktrans_ref_mutex);
58         dev = disk->private_data;
59
60         if (!dev)
61                 goto unlock;
62         kref_get(&dev->ref);
63 unlock:
64         mutex_unlock(&blktrans_ref_mutex);
65         return dev;
66 }
67
68 static void blktrans_dev_put(struct mtd_blktrans_dev *dev)
69 {
70         mutex_lock(&blktrans_ref_mutex);
71         kref_put(&dev->ref, blktrans_dev_release);
72         mutex_unlock(&blktrans_ref_mutex);
73 }
74
75
76 static blk_status_t do_blktrans_request(struct mtd_blktrans_ops *tr,
77                                struct mtd_blktrans_dev *dev,
78                                struct request *req)
79 {
80         unsigned long block, nsect;
81         char *buf;
82
83         block = blk_rq_pos(req) << 9 >> tr->blkshift;
84         nsect = blk_rq_cur_bytes(req) >> tr->blkshift;
85         buf = bio_data(req->bio);
86
87         if (req_op(req) == REQ_OP_FLUSH) {
88                 if (tr->flush(dev))
89                         return BLK_STS_IOERR;
90                 return BLK_STS_OK;
91         }
92
93         if (blk_rq_pos(req) + blk_rq_cur_sectors(req) >
94             get_capacity(req->rq_disk))
95                 return BLK_STS_IOERR;
96
97         switch (req_op(req)) {
98         case REQ_OP_DISCARD:
99                 if (tr->discard(dev, block, nsect))
100                         return BLK_STS_IOERR;
101                 return BLK_STS_OK;
102         case REQ_OP_READ:
103                 for (; nsect > 0; nsect--, block++, buf += tr->blksize)
104                         if (tr->readsect(dev, block, buf))
105                                 return BLK_STS_IOERR;
106                 rq_flush_dcache_pages(req);
107                 return BLK_STS_OK;
108         case REQ_OP_WRITE:
109                 if (!tr->writesect)
110                         return BLK_STS_IOERR;
111
112                 rq_flush_dcache_pages(req);
113                 for (; nsect > 0; nsect--, block++, buf += tr->blksize)
114                         if (tr->writesect(dev, block, buf))
115                                 return BLK_STS_IOERR;
116         default:
117                 return BLK_STS_IOERR;
118         }
119 }
120
121 int mtd_blktrans_cease_background(struct mtd_blktrans_dev *dev)
122 {
123         return dev->bg_stop;
124 }
125 EXPORT_SYMBOL_GPL(mtd_blktrans_cease_background);
126
127 static void mtd_blktrans_work(struct work_struct *work)
128 {
129         struct mtd_blktrans_dev *dev =
130                 container_of(work, struct mtd_blktrans_dev, work);
131         struct mtd_blktrans_ops *tr = dev->tr;
132         struct request_queue *rq = dev->rq;
133         struct request *req = NULL;
134         int background_done = 0;
135
136         spin_lock_irq(rq->queue_lock);
137
138         while (1) {
139                 blk_status_t res;
140
141                 dev->bg_stop = false;
142                 if (!req && !(req = blk_fetch_request(rq))) {
143                         if (tr->background && !background_done) {
144                                 spin_unlock_irq(rq->queue_lock);
145                                 mutex_lock(&dev->lock);
146                                 tr->background(dev);
147                                 mutex_unlock(&dev->lock);
148                                 spin_lock_irq(rq->queue_lock);
149                                 /*
150                                  * Do background processing just once per idle
151                                  * period.
152                                  */
153                                 background_done = !dev->bg_stop;
154                                 continue;
155                         }
156                         break;
157                 }
158
159                 spin_unlock_irq(rq->queue_lock);
160
161                 mutex_lock(&dev->lock);
162                 res = do_blktrans_request(dev->tr, dev, req);
163                 mutex_unlock(&dev->lock);
164
165                 spin_lock_irq(rq->queue_lock);
166
167                 if (!__blk_end_request_cur(req, res))
168                         req = NULL;
169
170                 background_done = 0;
171         }
172
173         spin_unlock_irq(rq->queue_lock);
174 }
175
176 static void mtd_blktrans_request(struct request_queue *rq)
177 {
178         struct mtd_blktrans_dev *dev;
179         struct request *req = NULL;
180
181         dev = rq->queuedata;
182
183         if (!dev)
184                 while ((req = blk_fetch_request(rq)) != NULL)
185                         __blk_end_request_all(req, BLK_STS_IOERR);
186         else
187                 queue_work(dev->wq, &dev->work);
188 }
189
190 static int blktrans_open(struct block_device *bdev, fmode_t mode)
191 {
192         struct mtd_blktrans_dev *dev = blktrans_dev_get(bdev->bd_disk);
193         int ret = 0;
194
195         if (!dev)
196                 return -ERESTARTSYS; /* FIXME: busy loop! -arnd*/
197
198         mutex_lock(&mtd_table_mutex);
199         mutex_lock(&dev->lock);
200
201         if (dev->open)
202                 goto unlock;
203
204         kref_get(&dev->ref);
205         __module_get(dev->tr->owner);
206
207         if (!dev->mtd)
208                 goto unlock;
209
210         if (dev->tr->open) {
211                 ret = dev->tr->open(dev);
212                 if (ret)
213                         goto error_put;
214         }
215
216         ret = __get_mtd_device(dev->mtd);
217         if (ret)
218                 goto error_release;
219         dev->file_mode = mode;
220
221 unlock:
222         dev->open++;
223         mutex_unlock(&dev->lock);
224         mutex_unlock(&mtd_table_mutex);
225         blktrans_dev_put(dev);
226         return ret;
227
228 error_release:
229         if (dev->tr->release)
230                 dev->tr->release(dev);
231 error_put:
232         module_put(dev->tr->owner);
233         kref_put(&dev->ref, blktrans_dev_release);
234         mutex_unlock(&dev->lock);
235         mutex_unlock(&mtd_table_mutex);
236         blktrans_dev_put(dev);
237         return ret;
238 }
239
240 static void blktrans_release(struct gendisk *disk, fmode_t mode)
241 {
242         struct mtd_blktrans_dev *dev = blktrans_dev_get(disk);
243
244         if (!dev)
245                 return;
246
247         mutex_lock(&mtd_table_mutex);
248         mutex_lock(&dev->lock);
249
250         if (--dev->open)
251                 goto unlock;
252
253         kref_put(&dev->ref, blktrans_dev_release);
254         module_put(dev->tr->owner);
255
256         if (dev->mtd) {
257                 if (dev->tr->release)
258                         dev->tr->release(dev);
259                 __put_mtd_device(dev->mtd);
260         }
261 unlock:
262         mutex_unlock(&dev->lock);
263         mutex_unlock(&mtd_table_mutex);
264         blktrans_dev_put(dev);
265 }
266
267 static int blktrans_getgeo(struct block_device *bdev, struct hd_geometry *geo)
268 {
269         struct mtd_blktrans_dev *dev = blktrans_dev_get(bdev->bd_disk);
270         int ret = -ENXIO;
271
272         if (!dev)
273                 return ret;
274
275         mutex_lock(&dev->lock);
276
277         if (!dev->mtd)
278                 goto unlock;
279
280         ret = dev->tr->getgeo ? dev->tr->getgeo(dev, geo) : -ENOTTY;
281 unlock:
282         mutex_unlock(&dev->lock);
283         blktrans_dev_put(dev);
284         return ret;
285 }
286
287 static int blktrans_ioctl(struct block_device *bdev, fmode_t mode,
288                               unsigned int cmd, unsigned long arg)
289 {
290         struct mtd_blktrans_dev *dev = blktrans_dev_get(bdev->bd_disk);
291         int ret = -ENXIO;
292
293         if (!dev)
294                 return ret;
295
296         mutex_lock(&dev->lock);
297
298         if (!dev->mtd)
299                 goto unlock;
300
301         switch (cmd) {
302         case BLKFLSBUF:
303                 ret = dev->tr->flush ? dev->tr->flush(dev) : 0;
304                 break;
305         default:
306                 ret = -ENOTTY;
307         }
308 unlock:
309         mutex_unlock(&dev->lock);
310         blktrans_dev_put(dev);
311         return ret;
312 }
313
314 static const struct block_device_operations mtd_block_ops = {
315         .owner          = THIS_MODULE,
316         .open           = blktrans_open,
317         .release        = blktrans_release,
318         .ioctl          = blktrans_ioctl,
319         .getgeo         = blktrans_getgeo,
320 };
321
322 int add_mtd_blktrans_dev(struct mtd_blktrans_dev *new)
323 {
324         struct mtd_blktrans_ops *tr = new->tr;
325         struct mtd_blktrans_dev *d;
326         int last_devnum = -1;
327         struct gendisk *gd;
328         int ret;
329
330         if (mutex_trylock(&mtd_table_mutex)) {
331                 mutex_unlock(&mtd_table_mutex);
332                 BUG();
333         }
334
335         mutex_lock(&blktrans_ref_mutex);
336         list_for_each_entry(d, &tr->devs, list) {
337                 if (new->devnum == -1) {
338                         /* Use first free number */
339                         if (d->devnum != last_devnum+1) {
340                                 /* Found a free devnum. Plug it in here */
341                                 new->devnum = last_devnum+1;
342                                 list_add_tail(&new->list, &d->list);
343                                 goto added;
344                         }
345                 } else if (d->devnum == new->devnum) {
346                         /* Required number taken */
347                         mutex_unlock(&blktrans_ref_mutex);
348                         return -EBUSY;
349                 } else if (d->devnum > new->devnum) {
350                         /* Required number was free */
351                         list_add_tail(&new->list, &d->list);
352                         goto added;
353                 }
354                 last_devnum = d->devnum;
355         }
356
357         ret = -EBUSY;
358         if (new->devnum == -1)
359                 new->devnum = last_devnum+1;
360
361         /* Check that the device and any partitions will get valid
362          * minor numbers and that the disk naming code below can cope
363          * with this number. */
364         if (new->devnum > (MINORMASK >> tr->part_bits) ||
365             (tr->part_bits && new->devnum >= 27 * 26)) {
366                 mutex_unlock(&blktrans_ref_mutex);
367                 goto error1;
368         }
369
370         list_add_tail(&new->list, &tr->devs);
371  added:
372         mutex_unlock(&blktrans_ref_mutex);
373
374         mutex_init(&new->lock);
375         kref_init(&new->ref);
376         if (!tr->writesect)
377                 new->readonly = 1;
378
379         /* Create gendisk */
380         ret = -ENOMEM;
381         gd = alloc_disk(1 << tr->part_bits);
382
383         if (!gd)
384                 goto error2;
385
386         new->disk = gd;
387         gd->private_data = new;
388         gd->major = tr->major;
389         gd->first_minor = (new->devnum) << tr->part_bits;
390         gd->fops = &mtd_block_ops;
391
392         if (tr->part_bits)
393                 if (new->devnum < 26)
394                         snprintf(gd->disk_name, sizeof(gd->disk_name),
395                                  "%s%c", tr->name, 'a' + new->devnum);
396                 else
397                         snprintf(gd->disk_name, sizeof(gd->disk_name),
398                                  "%s%c%c", tr->name,
399                                  'a' - 1 + new->devnum / 26,
400                                  'a' + new->devnum % 26);
401         else
402                 snprintf(gd->disk_name, sizeof(gd->disk_name),
403                          "%s%d", tr->name, new->devnum);
404
405         set_capacity(gd, ((u64)new->size * tr->blksize) >> 9);
406
407         /* Create the request queue */
408         spin_lock_init(&new->queue_lock);
409         new->rq = blk_init_queue(mtd_blktrans_request, &new->queue_lock);
410
411         if (!new->rq)
412                 goto error3;
413
414         if (tr->flush)
415                 blk_queue_write_cache(new->rq, true, false);
416
417         new->rq->queuedata = new;
418         blk_queue_logical_block_size(new->rq, tr->blksize);
419
420         blk_queue_bounce_limit(new->rq, BLK_BOUNCE_HIGH);
421         queue_flag_set_unlocked(QUEUE_FLAG_NONROT, new->rq);
422         queue_flag_clear_unlocked(QUEUE_FLAG_ADD_RANDOM, new->rq);
423
424         if (tr->discard) {
425                 queue_flag_set_unlocked(QUEUE_FLAG_DISCARD, new->rq);
426                 blk_queue_max_discard_sectors(new->rq, UINT_MAX);
427         }
428
429         gd->queue = new->rq;
430
431         /* Create processing workqueue */
432         new->wq = alloc_workqueue("%s%d", 0, 0,
433                                   tr->name, new->mtd->index);
434         if (!new->wq)
435                 goto error4;
436         INIT_WORK(&new->work, mtd_blktrans_work);
437
438         if (new->readonly)
439                 set_disk_ro(gd, 1);
440
441         device_add_disk(&new->mtd->dev, gd);
442
443         if (new->disk_attributes) {
444                 ret = sysfs_create_group(&disk_to_dev(gd)->kobj,
445                                         new->disk_attributes);
446                 WARN_ON(ret);
447         }
448         return 0;
449 error4:
450         blk_cleanup_queue(new->rq);
451 error3:
452         put_disk(new->disk);
453 error2:
454         list_del(&new->list);
455 error1:
456         return ret;
457 }
458
459 int del_mtd_blktrans_dev(struct mtd_blktrans_dev *old)
460 {
461         unsigned long flags;
462
463         if (mutex_trylock(&mtd_table_mutex)) {
464                 mutex_unlock(&mtd_table_mutex);
465                 BUG();
466         }
467
468         if (old->disk_attributes)
469                 sysfs_remove_group(&disk_to_dev(old->disk)->kobj,
470                                                 old->disk_attributes);
471
472         /* Stop new requests to arrive */
473         del_gendisk(old->disk);
474
475         /* Stop workqueue. This will perform any pending request. */
476         destroy_workqueue(old->wq);
477
478         /* Kill current requests */
479         spin_lock_irqsave(&old->queue_lock, flags);
480         old->rq->queuedata = NULL;
481         blk_start_queue(old->rq);
482         spin_unlock_irqrestore(&old->queue_lock, flags);
483
484         /* If the device is currently open, tell trans driver to close it,
485                 then put mtd device, and don't touch it again */
486         mutex_lock(&old->lock);
487         if (old->open) {
488                 if (old->tr->release)
489                         old->tr->release(old);
490                 __put_mtd_device(old->mtd);
491         }
492
493         old->mtd = NULL;
494
495         mutex_unlock(&old->lock);
496         blktrans_dev_put(old);
497         return 0;
498 }
499
500 static void blktrans_notify_remove(struct mtd_info *mtd)
501 {
502         struct mtd_blktrans_ops *tr;
503         struct mtd_blktrans_dev *dev, *next;
504
505         list_for_each_entry(tr, &blktrans_majors, list)
506                 list_for_each_entry_safe(dev, next, &tr->devs, list)
507                         if (dev->mtd == mtd)
508                                 tr->remove_dev(dev);
509 }
510
511 static void blktrans_notify_add(struct mtd_info *mtd)
512 {
513         struct mtd_blktrans_ops *tr;
514
515         if (mtd->type == MTD_ABSENT)
516                 return;
517
518         list_for_each_entry(tr, &blktrans_majors, list)
519                 tr->add_mtd(tr, mtd);
520 }
521
522 static struct mtd_notifier blktrans_notifier = {
523         .add = blktrans_notify_add,
524         .remove = blktrans_notify_remove,
525 };
526
527 int register_mtd_blktrans(struct mtd_blktrans_ops *tr)
528 {
529         struct mtd_info *mtd;
530         int ret;
531
532         /* Register the notifier if/when the first device type is
533            registered, to prevent the link/init ordering from fucking
534            us over. */
535         if (!blktrans_notifier.list.next)
536                 register_mtd_user(&blktrans_notifier);
537
538
539         mutex_lock(&mtd_table_mutex);
540
541         ret = register_blkdev(tr->major, tr->name);
542         if (ret < 0) {
543                 printk(KERN_WARNING "Unable to register %s block device on major %d: %d\n",
544                        tr->name, tr->major, ret);
545                 mutex_unlock(&mtd_table_mutex);
546                 return ret;
547         }
548
549         if (ret)
550                 tr->major = ret;
551
552         tr->blkshift = ffs(tr->blksize) - 1;
553
554         INIT_LIST_HEAD(&tr->devs);
555         list_add(&tr->list, &blktrans_majors);
556
557         mtd_for_each_device(mtd)
558                 if (mtd->type != MTD_ABSENT)
559                         tr->add_mtd(tr, mtd);
560
561         mutex_unlock(&mtd_table_mutex);
562         return 0;
563 }
564
565 int deregister_mtd_blktrans(struct mtd_blktrans_ops *tr)
566 {
567         struct mtd_blktrans_dev *dev, *next;
568
569         mutex_lock(&mtd_table_mutex);
570
571         /* Remove it from the list of active majors */
572         list_del(&tr->list);
573
574         list_for_each_entry_safe(dev, next, &tr->devs, list)
575                 tr->remove_dev(dev);
576
577         unregister_blkdev(tr->major, tr->name);
578         mutex_unlock(&mtd_table_mutex);
579
580         BUG_ON(!list_empty(&tr->devs));
581         return 0;
582 }
583
584 static void __exit mtd_blktrans_exit(void)
585 {
586         /* No race here -- if someone's currently in register_mtd_blktrans
587            we're screwed anyway. */
588         if (blktrans_notifier.list.next)
589                 unregister_mtd_user(&blktrans_notifier);
590 }
591
592 module_exit(mtd_blktrans_exit);
593
594 EXPORT_SYMBOL_GPL(register_mtd_blktrans);
595 EXPORT_SYMBOL_GPL(deregister_mtd_blktrans);
596 EXPORT_SYMBOL_GPL(add_mtd_blktrans_dev);
597 EXPORT_SYMBOL_GPL(del_mtd_blktrans_dev);
598
599 MODULE_AUTHOR("David Woodhouse <dwmw2@infradead.org>");
600 MODULE_LICENSE("GPL");
601 MODULE_DESCRIPTION("Common interface to block layer for MTD 'translation layers'");