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
38static LIST_HEAD(blktrans_majors);
39static DEFINE_MUTEX(blktrans_ref_mutex);
40
41static 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
53static 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);
63unlock:
64	mutex_unlock(&blktrans_ref_mutex);
65	return dev;
66}
67
68static 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
76static 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	switch(rq_data_dir(req)) {
101	case READ:
102		for (; nsect > 0; nsect--, block++, buf += tr->blksize)
103			if (tr->readsect(dev, block, buf))
104				return -EIO;
105		rq_flush_dcache_pages(req);
106		return 0;
107	case WRITE:
108		if (!tr->writesect)
109			return -EIO;
110
111		rq_flush_dcache_pages(req);
112		for (; nsect > 0; nsect--, block++, buf += tr->blksize)
113			if (tr->writesect(dev, block, buf))
114				return -EIO;
115		return 0;
116	default:
117		printk(KERN_NOTICE "Unknown request %u\n", rq_data_dir(req));
118		return -EIO;
119	}
120}
121
122int mtd_blktrans_cease_background(struct mtd_blktrans_dev *dev)
123{
124	return dev->bg_stop;
125}
126EXPORT_SYMBOL_GPL(mtd_blktrans_cease_background);
127
128static void mtd_blktrans_work(struct work_struct *work)
129{
130	struct mtd_blktrans_dev *dev =
131		container_of(work, struct mtd_blktrans_dev, work);
132	struct mtd_blktrans_ops *tr = dev->tr;
133	struct request_queue *rq = dev->rq;
134	struct request *req = NULL;
135	int background_done = 0;
136
137	spin_lock_irq(rq->queue_lock);
138
139	while (1) {
140		int res;
141
142		dev->bg_stop = false;
143		if (!req && !(req = blk_fetch_request(rq))) {
144			if (tr->background && !background_done) {
145				spin_unlock_irq(rq->queue_lock);
146				mutex_lock(&dev->lock);
147				tr->background(dev);
148				mutex_unlock(&dev->lock);
149				spin_lock_irq(rq->queue_lock);
150				/*
151				 * Do background processing just once per idle
152				 * period.
153				 */
154				background_done = !dev->bg_stop;
155				continue;
156			}
157			break;
158		}
159
160		spin_unlock_irq(rq->queue_lock);
161
162		mutex_lock(&dev->lock);
163		res = do_blktrans_request(dev->tr, dev, req);
164		mutex_unlock(&dev->lock);
165
166		spin_lock_irq(rq->queue_lock);
167
168		if (!__blk_end_request_cur(req, res))
169			req = NULL;
170
171		background_done = 0;
172	}
173
174	spin_unlock_irq(rq->queue_lock);
175}
176
177static void mtd_blktrans_request(struct request_queue *rq)
178{
179	struct mtd_blktrans_dev *dev;
180	struct request *req = NULL;
181
182	dev = rq->queuedata;
183
184	if (!dev)
185		while ((req = blk_fetch_request(rq)) != NULL)
186			__blk_end_request_all(req, -ENODEV);
187	else
188		queue_work(dev->wq, &dev->work);
189}
190
191static int blktrans_open(struct block_device *bdev, fmode_t mode)
192{
193	struct mtd_blktrans_dev *dev = blktrans_dev_get(bdev->bd_disk);
194	int ret = 0;
195
196	if (!dev)
197		return -ERESTARTSYS; /* FIXME: busy loop! -arnd*/
198
199	mutex_lock(&dev->lock);
200	mutex_lock(&mtd_table_mutex);
201
202	if (dev->open)
203		goto unlock;
204
205	kref_get(&dev->ref);
206	__module_get(dev->tr->owner);
207
208	if (!dev->mtd)
209		goto unlock;
210
211	if (dev->tr->open) {
212		ret = dev->tr->open(dev);
213		if (ret)
214			goto error_put;
215	}
216
217	ret = __get_mtd_device(dev->mtd);
218	if (ret)
219		goto error_release;
220	dev->file_mode = mode;
221
222unlock:
223	dev->open++;
224	mutex_unlock(&mtd_table_mutex);
225	mutex_unlock(&dev->lock);
226	blktrans_dev_put(dev);
227	return ret;
228
229error_release:
230	if (dev->tr->release)
231		dev->tr->release(dev);
232error_put:
233	module_put(dev->tr->owner);
234	kref_put(&dev->ref, blktrans_dev_release);
235	mutex_unlock(&mtd_table_mutex);
236	mutex_unlock(&dev->lock);
237	blktrans_dev_put(dev);
238	return ret;
239}
240
241static void blktrans_release(struct gendisk *disk, fmode_t mode)
242{
243	struct mtd_blktrans_dev *dev = blktrans_dev_get(disk);
244
245	if (!dev)
246		return;
247
248	mutex_lock(&dev->lock);
249	mutex_lock(&mtd_table_mutex);
250
251	if (--dev->open)
252		goto unlock;
253
254	kref_put(&dev->ref, blktrans_dev_release);
255	module_put(dev->tr->owner);
256
257	if (dev->mtd) {
258		if (dev->tr->release)
259			dev->tr->release(dev);
260		__put_mtd_device(dev->mtd);
261	}
262unlock:
263	mutex_unlock(&mtd_table_mutex);
264	mutex_unlock(&dev->lock);
265	blktrans_dev_put(dev);
266}
267
268static int blktrans_getgeo(struct block_device *bdev, struct hd_geometry *geo)
269{
270	struct mtd_blktrans_dev *dev = blktrans_dev_get(bdev->bd_disk);
271	int ret = -ENXIO;
272
273	if (!dev)
274		return ret;
275
276	mutex_lock(&dev->lock);
277
278	if (!dev->mtd)
279		goto unlock;
280
281	ret = dev->tr->getgeo ? dev->tr->getgeo(dev, geo) : 0;
282unlock:
283	mutex_unlock(&dev->lock);
284	blktrans_dev_put(dev);
285	return ret;
286}
287
288static int blktrans_ioctl(struct block_device *bdev, fmode_t mode,
289			      unsigned int cmd, unsigned long arg)
290{
291	struct mtd_blktrans_dev *dev = blktrans_dev_get(bdev->bd_disk);
292	int ret = -ENXIO;
293
294	if (!dev)
295		return ret;
296
297	mutex_lock(&dev->lock);
298
299	if (!dev->mtd)
300		goto unlock;
301
302	switch (cmd) {
303	case BLKFLSBUF:
304		ret = dev->tr->flush ? dev->tr->flush(dev) : 0;
305		break;
306	default:
307		ret = -ENOTTY;
308	}
309unlock:
310	mutex_unlock(&dev->lock);
311	blktrans_dev_put(dev);
312	return ret;
313}
314
315static const struct block_device_operations mtd_block_ops = {
316	.owner		= THIS_MODULE,
317	.open		= blktrans_open,
318	.release	= blktrans_release,
319	.ioctl		= blktrans_ioctl,
320	.getgeo		= blktrans_getgeo,
321};
322
323int add_mtd_blktrans_dev(struct mtd_blktrans_dev *new)
324{
325	struct mtd_blktrans_ops *tr = new->tr;
326	struct mtd_blktrans_dev *d;
327	int last_devnum = -1;
328	struct gendisk *gd;
329	int ret;
330
331	if (mutex_trylock(&mtd_table_mutex)) {
332		mutex_unlock(&mtd_table_mutex);
333		BUG();
334	}
335
336	mutex_lock(&blktrans_ref_mutex);
337	list_for_each_entry(d, &tr->devs, list) {
338		if (new->devnum == -1) {
339			/* Use first free number */
340			if (d->devnum != last_devnum+1) {
341				/* Found a free devnum. Plug it in here */
342				new->devnum = last_devnum+1;
343				list_add_tail(&new->list, &d->list);
344				goto added;
345			}
346		} else if (d->devnum == new->devnum) {
347			/* Required number taken */
348			mutex_unlock(&blktrans_ref_mutex);
349			return -EBUSY;
350		} else if (d->devnum > new->devnum) {
351			/* Required number was free */
352			list_add_tail(&new->list, &d->list);
353			goto added;
354		}
355		last_devnum = d->devnum;
356	}
357
358	ret = -EBUSY;
359	if (new->devnum == -1)
360		new->devnum = last_devnum+1;
361
362	/* Check that the device and any partitions will get valid
363	 * minor numbers and that the disk naming code below can cope
364	 * with this number. */
365	if (new->devnum > (MINORMASK >> tr->part_bits) ||
366	    (tr->part_bits && new->devnum >= 27 * 26)) {
367		mutex_unlock(&blktrans_ref_mutex);
368		goto error1;
369	}
370
371	list_add_tail(&new->list, &tr->devs);
372 added:
373	mutex_unlock(&blktrans_ref_mutex);
374
375	mutex_init(&new->lock);
376	kref_init(&new->ref);
377	if (!tr->writesect)
378		new->readonly = 1;
379
380	/* Create gendisk */
381	ret = -ENOMEM;
382	gd = alloc_disk(1 << tr->part_bits);
383
384	if (!gd)
385		goto error2;
386
387	new->disk = gd;
388	gd->private_data = new;
389	gd->major = tr->major;
390	gd->first_minor = (new->devnum) << tr->part_bits;
391	gd->fops = &mtd_block_ops;
392
393	if (tr->part_bits)
394		if (new->devnum < 26)
395			snprintf(gd->disk_name, sizeof(gd->disk_name),
396				 "%s%c", tr->name, 'a' + new->devnum);
397		else
398			snprintf(gd->disk_name, sizeof(gd->disk_name),
399				 "%s%c%c", tr->name,
400				 'a' - 1 + new->devnum / 26,
401				 'a' + new->devnum % 26);
402	else
403		snprintf(gd->disk_name, sizeof(gd->disk_name),
404			 "%s%d", tr->name, new->devnum);
405
406	set_capacity(gd, (new->size * tr->blksize) >> 9);
407
408	/* Create the request queue */
409	spin_lock_init(&new->queue_lock);
410	new->rq = blk_init_queue(mtd_blktrans_request, &new->queue_lock);
411
412	if (!new->rq)
413		goto error3;
414
415	if (tr->flush)
416		blk_queue_flush(new->rq, REQ_FLUSH);
417
418	new->rq->queuedata = new;
419	blk_queue_logical_block_size(new->rq, tr->blksize);
420
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		new->rq->limits.max_discard_sectors = 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	gd->driverfs_dev = &new->mtd->dev;
439
440	if (new->readonly)
441		set_disk_ro(gd, 1);
442
443	add_disk(gd);
444
445	if (new->disk_attributes) {
446		ret = sysfs_create_group(&disk_to_dev(gd)->kobj,
447					new->disk_attributes);
448		WARN_ON(ret);
449	}
450	return 0;
451error4:
452	blk_cleanup_queue(new->rq);
453error3:
454	put_disk(new->disk);
455error2:
456	list_del(&new->list);
457error1:
458	return ret;
459}
460
461int del_mtd_blktrans_dev(struct mtd_blktrans_dev *old)
462{
463	unsigned long flags;
464
465	if (mutex_trylock(&mtd_table_mutex)) {
466		mutex_unlock(&mtd_table_mutex);
467		BUG();
468	}
469
470	if (old->disk_attributes)
471		sysfs_remove_group(&disk_to_dev(old->disk)->kobj,
472						old->disk_attributes);
473
474	/* Stop new requests to arrive */
475	del_gendisk(old->disk);
476
477	/* Stop workqueue. This will perform any pending request. */
478	destroy_workqueue(old->wq);
479
480	/* Kill current requests */
481	spin_lock_irqsave(&old->queue_lock, flags);
482	old->rq->queuedata = NULL;
483	blk_start_queue(old->rq);
484	spin_unlock_irqrestore(&old->queue_lock, flags);
485
486	/* If the device is currently open, tell trans driver to close it,
487		then put mtd device, and don't touch it again */
488	mutex_lock(&old->lock);
489	if (old->open) {
490		if (old->tr->release)
491			old->tr->release(old);
492		__put_mtd_device(old->mtd);
493	}
494
495	old->mtd = NULL;
496
497	mutex_unlock(&old->lock);
498	blktrans_dev_put(old);
499	return 0;
500}
501
502static void blktrans_notify_remove(struct mtd_info *mtd)
503{
504	struct mtd_blktrans_ops *tr;
505	struct mtd_blktrans_dev *dev, *next;
506
507	list_for_each_entry(tr, &blktrans_majors, list)
508		list_for_each_entry_safe(dev, next, &tr->devs, list)
509			if (dev->mtd == mtd)
510				tr->remove_dev(dev);
511}
512
513static void blktrans_notify_add(struct mtd_info *mtd)
514{
515	struct mtd_blktrans_ops *tr;
516
517	if (mtd->type == MTD_ABSENT)
518		return;
519
520	list_for_each_entry(tr, &blktrans_majors, list)
521		tr->add_mtd(tr, mtd);
522}
523
524static struct mtd_notifier blktrans_notifier = {
525	.add = blktrans_notify_add,
526	.remove = blktrans_notify_remove,
527};
528
529int register_mtd_blktrans(struct mtd_blktrans_ops *tr)
530{
531	struct mtd_info *mtd;
532	int ret;
533
534	/* Register the notifier if/when the first device type is
535	   registered, to prevent the link/init ordering from fucking
536	   us over. */
537	if (!blktrans_notifier.list.next)
538		register_mtd_user(&blktrans_notifier);
539
540
541	mutex_lock(&mtd_table_mutex);
542
543	ret = register_blkdev(tr->major, tr->name);
544	if (ret < 0) {
545		printk(KERN_WARNING "Unable to register %s block device on major %d: %d\n",
546		       tr->name, tr->major, ret);
547		mutex_unlock(&mtd_table_mutex);
548		return ret;
549	}
550
551	if (ret)
552		tr->major = ret;
553
554	tr->blkshift = ffs(tr->blksize) - 1;
555
556	INIT_LIST_HEAD(&tr->devs);
557	list_add(&tr->list, &blktrans_majors);
558
559	mtd_for_each_device(mtd)
560		if (mtd->type != MTD_ABSENT)
561			tr->add_mtd(tr, mtd);
562
563	mutex_unlock(&mtd_table_mutex);
564	return 0;
565}
566
567int deregister_mtd_blktrans(struct mtd_blktrans_ops *tr)
568{
569	struct mtd_blktrans_dev *dev, *next;
570
571	mutex_lock(&mtd_table_mutex);
572
573	/* Remove it from the list of active majors */
574	list_del(&tr->list);
575
576	list_for_each_entry_safe(dev, next, &tr->devs, list)
577		tr->remove_dev(dev);
578
579	unregister_blkdev(tr->major, tr->name);
580	mutex_unlock(&mtd_table_mutex);
581
582	BUG_ON(!list_empty(&tr->devs));
583	return 0;
584}
585
586static void __exit mtd_blktrans_exit(void)
587{
588	/* No race here -- if someone's currently in register_mtd_blktrans
589	   we're screwed anyway. */
590	if (blktrans_notifier.list.next)
591		unregister_mtd_user(&blktrans_notifier);
592}
593
594module_exit(mtd_blktrans_exit);
595
596EXPORT_SYMBOL_GPL(register_mtd_blktrans);
597EXPORT_SYMBOL_GPL(deregister_mtd_blktrans);
598EXPORT_SYMBOL_GPL(add_mtd_blktrans_dev);
599EXPORT_SYMBOL_GPL(del_mtd_blktrans_dev);
600
601MODULE_AUTHOR("David Woodhouse <dwmw2@infradead.org>");
602MODULE_LICENSE("GPL");
603MODULE_DESCRIPTION("Common interface to block layer for MTD 'translation layers'");
604