GNU Linux-libre 4.4.288-gnu1
[releases.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 <asm/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 int 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->cmd_type != REQ_TYPE_FS)
88                 return -EIO;
89
90         if (req->cmd_flags & REQ_FLUSH)
91                 return tr->flush(dev);
92
93         if (blk_rq_pos(req) + blk_rq_cur_sectors(req) >
94             get_capacity(req->rq_disk))
95                 return -EIO;
96
97         if (req->cmd_flags & REQ_DISCARD)
98                 return tr->discard(dev, block, nsect);
99
100         if (rq_data_dir(req) == READ) {
101                 for (; nsect > 0; nsect--, block++, buf += tr->blksize)
102                         if (tr->readsect(dev, block, buf))
103                                 return -EIO;
104                 rq_flush_dcache_pages(req);
105                 return 0;
106         } else {
107                 if (!tr->writesect)
108                         return -EIO;
109
110                 rq_flush_dcache_pages(req);
111                 for (; nsect > 0; nsect--, block++, buf += tr->blksize)
112                         if (tr->writesect(dev, block, buf))
113                                 return -EIO;
114                 return 0;
115         }
116 }
117
118 int mtd_blktrans_cease_background(struct mtd_blktrans_dev *dev)
119 {
120         return dev->bg_stop;
121 }
122 EXPORT_SYMBOL_GPL(mtd_blktrans_cease_background);
123
124 static void mtd_blktrans_work(struct work_struct *work)
125 {
126         struct mtd_blktrans_dev *dev =
127                 container_of(work, struct mtd_blktrans_dev, work);
128         struct mtd_blktrans_ops *tr = dev->tr;
129         struct request_queue *rq = dev->rq;
130         struct request *req = NULL;
131         int background_done = 0;
132
133         spin_lock_irq(rq->queue_lock);
134
135         while (1) {
136                 int res;
137
138                 dev->bg_stop = false;
139                 if (!req && !(req = blk_fetch_request(rq))) {
140                         if (tr->background && !background_done) {
141                                 spin_unlock_irq(rq->queue_lock);
142                                 mutex_lock(&dev->lock);
143                                 tr->background(dev);
144                                 mutex_unlock(&dev->lock);
145                                 spin_lock_irq(rq->queue_lock);
146                                 /*
147                                  * Do background processing just once per idle
148                                  * period.
149                                  */
150                                 background_done = !dev->bg_stop;
151                                 continue;
152                         }
153                         break;
154                 }
155
156                 spin_unlock_irq(rq->queue_lock);
157
158                 mutex_lock(&dev->lock);
159                 res = do_blktrans_request(dev->tr, dev, req);
160                 mutex_unlock(&dev->lock);
161
162                 spin_lock_irq(rq->queue_lock);
163
164                 if (!__blk_end_request_cur(req, res))
165                         req = NULL;
166
167                 background_done = 0;
168         }
169
170         spin_unlock_irq(rq->queue_lock);
171 }
172
173 static void mtd_blktrans_request(struct request_queue *rq)
174 {
175         struct mtd_blktrans_dev *dev;
176         struct request *req = NULL;
177
178         dev = rq->queuedata;
179
180         if (!dev)
181                 while ((req = blk_fetch_request(rq)) != NULL)
182                         __blk_end_request_all(req, -ENODEV);
183         else
184                 queue_work(dev->wq, &dev->work);
185 }
186
187 static int blktrans_open(struct block_device *bdev, fmode_t mode)
188 {
189         struct mtd_blktrans_dev *dev = blktrans_dev_get(bdev->bd_disk);
190         int ret = 0;
191
192         if (!dev)
193                 return -ERESTARTSYS; /* FIXME: busy loop! -arnd*/
194
195         mutex_lock(&mtd_table_mutex);
196         mutex_lock(&dev->lock);
197
198         if (dev->open)
199                 goto unlock;
200
201         kref_get(&dev->ref);
202         __module_get(dev->tr->owner);
203
204         if (!dev->mtd)
205                 goto unlock;
206
207         if (dev->tr->open) {
208                 ret = dev->tr->open(dev);
209                 if (ret)
210                         goto error_put;
211         }
212
213         ret = __get_mtd_device(dev->mtd);
214         if (ret)
215                 goto error_release;
216         dev->file_mode = mode;
217
218 unlock:
219         dev->open++;
220         mutex_unlock(&dev->lock);
221         mutex_unlock(&mtd_table_mutex);
222         blktrans_dev_put(dev);
223         return ret;
224
225 error_release:
226         if (dev->tr->release)
227                 dev->tr->release(dev);
228 error_put:
229         module_put(dev->tr->owner);
230         kref_put(&dev->ref, blktrans_dev_release);
231         mutex_unlock(&dev->lock);
232         mutex_unlock(&mtd_table_mutex);
233         blktrans_dev_put(dev);
234         return ret;
235 }
236
237 static void blktrans_release(struct gendisk *disk, fmode_t mode)
238 {
239         struct mtd_blktrans_dev *dev = blktrans_dev_get(disk);
240
241         if (!dev)
242                 return;
243
244         mutex_lock(&mtd_table_mutex);
245         mutex_lock(&dev->lock);
246
247         if (--dev->open)
248                 goto unlock;
249
250         kref_put(&dev->ref, blktrans_dev_release);
251         module_put(dev->tr->owner);
252
253         if (dev->mtd) {
254                 if (dev->tr->release)
255                         dev->tr->release(dev);
256                 __put_mtd_device(dev->mtd);
257         }
258 unlock:
259         mutex_unlock(&dev->lock);
260         mutex_unlock(&mtd_table_mutex);
261         blktrans_dev_put(dev);
262 }
263
264 static int blktrans_getgeo(struct block_device *bdev, struct hd_geometry *geo)
265 {
266         struct mtd_blktrans_dev *dev = blktrans_dev_get(bdev->bd_disk);
267         int ret = -ENXIO;
268
269         if (!dev)
270                 return ret;
271
272         mutex_lock(&dev->lock);
273
274         if (!dev->mtd)
275                 goto unlock;
276
277         ret = dev->tr->getgeo ? dev->tr->getgeo(dev, geo) : -ENOTTY;
278 unlock:
279         mutex_unlock(&dev->lock);
280         blktrans_dev_put(dev);
281         return ret;
282 }
283
284 static int blktrans_ioctl(struct block_device *bdev, fmode_t mode,
285                               unsigned int cmd, unsigned long arg)
286 {
287         struct mtd_blktrans_dev *dev = blktrans_dev_get(bdev->bd_disk);
288         int ret = -ENXIO;
289
290         if (!dev)
291                 return ret;
292
293         mutex_lock(&dev->lock);
294
295         if (!dev->mtd)
296                 goto unlock;
297
298         switch (cmd) {
299         case BLKFLSBUF:
300                 ret = dev->tr->flush ? dev->tr->flush(dev) : 0;
301                 break;
302         default:
303                 ret = -ENOTTY;
304         }
305 unlock:
306         mutex_unlock(&dev->lock);
307         blktrans_dev_put(dev);
308         return ret;
309 }
310
311 static const struct block_device_operations mtd_block_ops = {
312         .owner          = THIS_MODULE,
313         .open           = blktrans_open,
314         .release        = blktrans_release,
315         .ioctl          = blktrans_ioctl,
316         .getgeo         = blktrans_getgeo,
317 };
318
319 int add_mtd_blktrans_dev(struct mtd_blktrans_dev *new)
320 {
321         struct mtd_blktrans_ops *tr = new->tr;
322         struct mtd_blktrans_dev *d;
323         int last_devnum = -1;
324         struct gendisk *gd;
325         int ret;
326
327         if (mutex_trylock(&mtd_table_mutex)) {
328                 mutex_unlock(&mtd_table_mutex);
329                 BUG();
330         }
331
332         mutex_lock(&blktrans_ref_mutex);
333         list_for_each_entry(d, &tr->devs, list) {
334                 if (new->devnum == -1) {
335                         /* Use first free number */
336                         if (d->devnum != last_devnum+1) {
337                                 /* Found a free devnum. Plug it in here */
338                                 new->devnum = last_devnum+1;
339                                 list_add_tail(&new->list, &d->list);
340                                 goto added;
341                         }
342                 } else if (d->devnum == new->devnum) {
343                         /* Required number taken */
344                         mutex_unlock(&blktrans_ref_mutex);
345                         return -EBUSY;
346                 } else if (d->devnum > new->devnum) {
347                         /* Required number was free */
348                         list_add_tail(&new->list, &d->list);
349                         goto added;
350                 }
351                 last_devnum = d->devnum;
352         }
353
354         ret = -EBUSY;
355         if (new->devnum == -1)
356                 new->devnum = last_devnum+1;
357
358         /* Check that the device and any partitions will get valid
359          * minor numbers and that the disk naming code below can cope
360          * with this number. */
361         if (new->devnum > (MINORMASK >> tr->part_bits) ||
362             (tr->part_bits && new->devnum >= 27 * 26)) {
363                 mutex_unlock(&blktrans_ref_mutex);
364                 goto error1;
365         }
366
367         list_add_tail(&new->list, &tr->devs);
368  added:
369         mutex_unlock(&blktrans_ref_mutex);
370
371         mutex_init(&new->lock);
372         kref_init(&new->ref);
373         if (!tr->writesect)
374                 new->readonly = 1;
375
376         /* Create gendisk */
377         ret = -ENOMEM;
378         gd = alloc_disk(1 << tr->part_bits);
379
380         if (!gd)
381                 goto error2;
382
383         new->disk = gd;
384         gd->private_data = new;
385         gd->major = tr->major;
386         gd->first_minor = (new->devnum) << tr->part_bits;
387         gd->fops = &mtd_block_ops;
388
389         if (tr->part_bits)
390                 if (new->devnum < 26)
391                         snprintf(gd->disk_name, sizeof(gd->disk_name),
392                                  "%s%c", tr->name, 'a' + new->devnum);
393                 else
394                         snprintf(gd->disk_name, sizeof(gd->disk_name),
395                                  "%s%c%c", tr->name,
396                                  'a' - 1 + new->devnum / 26,
397                                  'a' + new->devnum % 26);
398         else
399                 snprintf(gd->disk_name, sizeof(gd->disk_name),
400                          "%s%d", tr->name, new->devnum);
401
402         set_capacity(gd, ((u64)new->size * tr->blksize) >> 9);
403
404         /* Create the request queue */
405         spin_lock_init(&new->queue_lock);
406         new->rq = blk_init_queue(mtd_blktrans_request, &new->queue_lock);
407
408         if (!new->rq)
409                 goto error3;
410
411         if (tr->flush)
412                 blk_queue_flush(new->rq, REQ_FLUSH);
413
414         new->rq->queuedata = new;
415         blk_queue_logical_block_size(new->rq, tr->blksize);
416
417         queue_flag_set_unlocked(QUEUE_FLAG_NONROT, new->rq);
418         queue_flag_clear_unlocked(QUEUE_FLAG_ADD_RANDOM, new->rq);
419
420         if (tr->discard) {
421                 queue_flag_set_unlocked(QUEUE_FLAG_DISCARD, new->rq);
422                 blk_queue_max_discard_sectors(new->rq, UINT_MAX);
423         }
424
425         gd->queue = new->rq;
426
427         /* Create processing workqueue */
428         new->wq = alloc_workqueue("%s%d", 0, 0,
429                                   tr->name, new->mtd->index);
430         if (!new->wq)
431                 goto error4;
432         INIT_WORK(&new->work, mtd_blktrans_work);
433
434         gd->driverfs_dev = &new->mtd->dev;
435
436         if (new->readonly)
437                 set_disk_ro(gd, 1);
438
439         add_disk(gd);
440
441         if (new->disk_attributes) {
442                 ret = sysfs_create_group(&disk_to_dev(gd)->kobj,
443                                         new->disk_attributes);
444                 WARN_ON(ret);
445         }
446         return 0;
447 error4:
448         blk_cleanup_queue(new->rq);
449 error3:
450         put_disk(new->disk);
451 error2:
452         list_del(&new->list);
453 error1:
454         return ret;
455 }
456
457 int del_mtd_blktrans_dev(struct mtd_blktrans_dev *old)
458 {
459         unsigned long flags;
460
461         if (mutex_trylock(&mtd_table_mutex)) {
462                 mutex_unlock(&mtd_table_mutex);
463                 BUG();
464         }
465
466         if (old->disk_attributes)
467                 sysfs_remove_group(&disk_to_dev(old->disk)->kobj,
468                                                 old->disk_attributes);
469
470         /* Stop new requests to arrive */
471         del_gendisk(old->disk);
472
473         /* Stop workqueue. This will perform any pending request. */
474         destroy_workqueue(old->wq);
475
476         /* Kill current requests */
477         spin_lock_irqsave(&old->queue_lock, flags);
478         old->rq->queuedata = NULL;
479         blk_start_queue(old->rq);
480         spin_unlock_irqrestore(&old->queue_lock, flags);
481
482         /* If the device is currently open, tell trans driver to close it,
483                 then put mtd device, and don't touch it again */
484         mutex_lock(&old->lock);
485         if (old->open) {
486                 if (old->tr->release)
487                         old->tr->release(old);
488                 __put_mtd_device(old->mtd);
489         }
490
491         old->mtd = NULL;
492
493         mutex_unlock(&old->lock);
494         blktrans_dev_put(old);
495         return 0;
496 }
497
498 static void blktrans_notify_remove(struct mtd_info *mtd)
499 {
500         struct mtd_blktrans_ops *tr;
501         struct mtd_blktrans_dev *dev, *next;
502
503         list_for_each_entry(tr, &blktrans_majors, list)
504                 list_for_each_entry_safe(dev, next, &tr->devs, list)
505                         if (dev->mtd == mtd)
506                                 tr->remove_dev(dev);
507 }
508
509 static void blktrans_notify_add(struct mtd_info *mtd)
510 {
511         struct mtd_blktrans_ops *tr;
512
513         if (mtd->type == MTD_ABSENT)
514                 return;
515
516         list_for_each_entry(tr, &blktrans_majors, list)
517                 tr->add_mtd(tr, mtd);
518 }
519
520 static struct mtd_notifier blktrans_notifier = {
521         .add = blktrans_notify_add,
522         .remove = blktrans_notify_remove,
523 };
524
525 int register_mtd_blktrans(struct mtd_blktrans_ops *tr)
526 {
527         struct mtd_info *mtd;
528         int ret;
529
530         /* Register the notifier if/when the first device type is
531            registered, to prevent the link/init ordering from fucking
532            us over. */
533         if (!blktrans_notifier.list.next)
534                 register_mtd_user(&blktrans_notifier);
535
536
537         mutex_lock(&mtd_table_mutex);
538
539         ret = register_blkdev(tr->major, tr->name);
540         if (ret < 0) {
541                 printk(KERN_WARNING "Unable to register %s block device on major %d: %d\n",
542                        tr->name, tr->major, ret);
543                 mutex_unlock(&mtd_table_mutex);
544                 return ret;
545         }
546
547         if (ret)
548                 tr->major = ret;
549
550         tr->blkshift = ffs(tr->blksize) - 1;
551
552         INIT_LIST_HEAD(&tr->devs);
553         list_add(&tr->list, &blktrans_majors);
554
555         mtd_for_each_device(mtd)
556                 if (mtd->type != MTD_ABSENT)
557                         tr->add_mtd(tr, mtd);
558
559         mutex_unlock(&mtd_table_mutex);
560         return 0;
561 }
562
563 int deregister_mtd_blktrans(struct mtd_blktrans_ops *tr)
564 {
565         struct mtd_blktrans_dev *dev, *next;
566
567         mutex_lock(&mtd_table_mutex);
568
569         /* Remove it from the list of active majors */
570         list_del(&tr->list);
571
572         list_for_each_entry_safe(dev, next, &tr->devs, list)
573                 tr->remove_dev(dev);
574
575         unregister_blkdev(tr->major, tr->name);
576         mutex_unlock(&mtd_table_mutex);
577
578         BUG_ON(!list_empty(&tr->devs));
579         return 0;
580 }
581
582 static void __exit mtd_blktrans_exit(void)
583 {
584         /* No race here -- if someone's currently in register_mtd_blktrans
585            we're screwed anyway. */
586         if (blktrans_notifier.list.next)
587                 unregister_mtd_user(&blktrans_notifier);
588 }
589
590 module_exit(mtd_blktrans_exit);
591
592 EXPORT_SYMBOL_GPL(register_mtd_blktrans);
593 EXPORT_SYMBOL_GPL(deregister_mtd_blktrans);
594 EXPORT_SYMBOL_GPL(add_mtd_blktrans_dev);
595 EXPORT_SYMBOL_GPL(del_mtd_blktrans_dev);
596
597 MODULE_AUTHOR("David Woodhouse <dwmw2@infradead.org>");
598 MODULE_LICENSE("GPL");
599 MODULE_DESCRIPTION("Common interface to block layer for MTD 'translation layers'");