xref: /openbmc/linux/drivers/mtd/mtd_blkdevs.c (revision 22246614)
1 /*
2  * $Id: mtd_blkdevs.c,v 1.27 2005/11/07 11:14:20 gleixner Exp $
3  *
4  * (C) 2003 David Woodhouse <dwmw2@infradead.org>
5  *
6  * Interface to Linux 2.5 block layer for MTD 'translation layers'.
7  *
8  */
9 
10 #include <linux/kernel.h>
11 #include <linux/slab.h>
12 #include <linux/module.h>
13 #include <linux/list.h>
14 #include <linux/fs.h>
15 #include <linux/mtd/blktrans.h>
16 #include <linux/mtd/mtd.h>
17 #include <linux/blkdev.h>
18 #include <linux/blkpg.h>
19 #include <linux/freezer.h>
20 #include <linux/spinlock.h>
21 #include <linux/hdreg.h>
22 #include <linux/init.h>
23 #include <linux/mutex.h>
24 #include <linux/kthread.h>
25 #include <asm/uaccess.h>
26 
27 #include "mtdcore.h"
28 
29 static LIST_HEAD(blktrans_majors);
30 
31 struct mtd_blkcore_priv {
32 	struct task_struct *thread;
33 	struct request_queue *rq;
34 	spinlock_t queue_lock;
35 };
36 
37 static int do_blktrans_request(struct mtd_blktrans_ops *tr,
38 			       struct mtd_blktrans_dev *dev,
39 			       struct request *req)
40 {
41 	unsigned long block, nsect;
42 	char *buf;
43 
44 	block = req->sector << 9 >> tr->blkshift;
45 	nsect = req->current_nr_sectors << 9 >> tr->blkshift;
46 
47 	buf = req->buffer;
48 
49 	if (!blk_fs_request(req))
50 		return 0;
51 
52 	if (req->sector + req->current_nr_sectors > get_capacity(req->rq_disk))
53 		return 0;
54 
55 	switch(rq_data_dir(req)) {
56 	case READ:
57 		for (; nsect > 0; nsect--, block++, buf += tr->blksize)
58 			if (tr->readsect(dev, block, buf))
59 				return 0;
60 		return 1;
61 
62 	case WRITE:
63 		if (!tr->writesect)
64 			return 0;
65 
66 		for (; nsect > 0; nsect--, block++, buf += tr->blksize)
67 			if (tr->writesect(dev, block, buf))
68 				return 0;
69 		return 1;
70 
71 	default:
72 		printk(KERN_NOTICE "Unknown request %u\n", rq_data_dir(req));
73 		return 0;
74 	}
75 }
76 
77 static int mtd_blktrans_thread(void *arg)
78 {
79 	struct mtd_blktrans_ops *tr = arg;
80 	struct request_queue *rq = tr->blkcore_priv->rq;
81 
82 	/* we might get involved when memory gets low, so use PF_MEMALLOC */
83 	current->flags |= PF_MEMALLOC;
84 
85 	spin_lock_irq(rq->queue_lock);
86 	while (!kthread_should_stop()) {
87 		struct request *req;
88 		struct mtd_blktrans_dev *dev;
89 		int res = 0;
90 
91 		req = elv_next_request(rq);
92 
93 		if (!req) {
94 			set_current_state(TASK_INTERRUPTIBLE);
95 			spin_unlock_irq(rq->queue_lock);
96 			schedule();
97 			spin_lock_irq(rq->queue_lock);
98 			continue;
99 		}
100 
101 		dev = req->rq_disk->private_data;
102 		tr = dev->tr;
103 
104 		spin_unlock_irq(rq->queue_lock);
105 
106 		mutex_lock(&dev->lock);
107 		res = do_blktrans_request(tr, dev, req);
108 		mutex_unlock(&dev->lock);
109 
110 		spin_lock_irq(rq->queue_lock);
111 
112 		end_request(req, res);
113 	}
114 	spin_unlock_irq(rq->queue_lock);
115 
116 	return 0;
117 }
118 
119 static void mtd_blktrans_request(struct request_queue *rq)
120 {
121 	struct mtd_blktrans_ops *tr = rq->queuedata;
122 	wake_up_process(tr->blkcore_priv->thread);
123 }
124 
125 
126 static int blktrans_open(struct inode *i, struct file *f)
127 {
128 	struct mtd_blktrans_dev *dev;
129 	struct mtd_blktrans_ops *tr;
130 	int ret = -ENODEV;
131 
132 	dev = i->i_bdev->bd_disk->private_data;
133 	tr = dev->tr;
134 
135 	if (!try_module_get(dev->mtd->owner))
136 		goto out;
137 
138 	if (!try_module_get(tr->owner))
139 		goto out_tr;
140 
141 	/* FIXME: Locking. A hot pluggable device can go away
142 	   (del_mtd_device can be called for it) without its module
143 	   being unloaded. */
144 	dev->mtd->usecount++;
145 
146 	ret = 0;
147 	if (tr->open && (ret = tr->open(dev))) {
148 		dev->mtd->usecount--;
149 		module_put(dev->mtd->owner);
150 	out_tr:
151 		module_put(tr->owner);
152 	}
153  out:
154 	return ret;
155 }
156 
157 static int blktrans_release(struct inode *i, struct file *f)
158 {
159 	struct mtd_blktrans_dev *dev;
160 	struct mtd_blktrans_ops *tr;
161 	int ret = 0;
162 
163 	dev = i->i_bdev->bd_disk->private_data;
164 	tr = dev->tr;
165 
166 	if (tr->release)
167 		ret = tr->release(dev);
168 
169 	if (!ret) {
170 		dev->mtd->usecount--;
171 		module_put(dev->mtd->owner);
172 		module_put(tr->owner);
173 	}
174 
175 	return ret;
176 }
177 
178 static int blktrans_getgeo(struct block_device *bdev, struct hd_geometry *geo)
179 {
180 	struct mtd_blktrans_dev *dev = bdev->bd_disk->private_data;
181 
182 	if (dev->tr->getgeo)
183 		return dev->tr->getgeo(dev, geo);
184 	return -ENOTTY;
185 }
186 
187 static int blktrans_ioctl(struct inode *inode, struct file *file,
188 			      unsigned int cmd, unsigned long arg)
189 {
190 	struct mtd_blktrans_dev *dev = inode->i_bdev->bd_disk->private_data;
191 	struct mtd_blktrans_ops *tr = dev->tr;
192 
193 	switch (cmd) {
194 	case BLKFLSBUF:
195 		if (tr->flush)
196 			return tr->flush(dev);
197 		/* The core code did the work, we had nothing to do. */
198 		return 0;
199 	default:
200 		return -ENOTTY;
201 	}
202 }
203 
204 static struct block_device_operations mtd_blktrans_ops = {
205 	.owner		= THIS_MODULE,
206 	.open		= blktrans_open,
207 	.release	= blktrans_release,
208 	.ioctl		= blktrans_ioctl,
209 	.getgeo		= blktrans_getgeo,
210 };
211 
212 int add_mtd_blktrans_dev(struct mtd_blktrans_dev *new)
213 {
214 	struct mtd_blktrans_ops *tr = new->tr;
215 	struct list_head *this;
216 	int last_devnum = -1;
217 	struct gendisk *gd;
218 
219 	if (mutex_trylock(&mtd_table_mutex)) {
220 		mutex_unlock(&mtd_table_mutex);
221 		BUG();
222 	}
223 
224 	list_for_each(this, &tr->devs) {
225 		struct mtd_blktrans_dev *d = list_entry(this, struct mtd_blktrans_dev, list);
226 		if (new->devnum == -1) {
227 			/* Use first free number */
228 			if (d->devnum != last_devnum+1) {
229 				/* Found a free devnum. Plug it in here */
230 				new->devnum = last_devnum+1;
231 				list_add_tail(&new->list, &d->list);
232 				goto added;
233 			}
234 		} else if (d->devnum == new->devnum) {
235 			/* Required number taken */
236 			return -EBUSY;
237 		} else if (d->devnum > new->devnum) {
238 			/* Required number was free */
239 			list_add_tail(&new->list, &d->list);
240 			goto added;
241 		}
242 		last_devnum = d->devnum;
243 	}
244 	if (new->devnum == -1)
245 		new->devnum = last_devnum+1;
246 
247 	if ((new->devnum << tr->part_bits) > 256) {
248 		return -EBUSY;
249 	}
250 
251 	list_add_tail(&new->list, &tr->devs);
252  added:
253 	mutex_init(&new->lock);
254 	if (!tr->writesect)
255 		new->readonly = 1;
256 
257 	gd = alloc_disk(1 << tr->part_bits);
258 	if (!gd) {
259 		list_del(&new->list);
260 		return -ENOMEM;
261 	}
262 	gd->major = tr->major;
263 	gd->first_minor = (new->devnum) << tr->part_bits;
264 	gd->fops = &mtd_blktrans_ops;
265 
266 	if (tr->part_bits)
267 		if (new->devnum < 26)
268 			snprintf(gd->disk_name, sizeof(gd->disk_name),
269 				 "%s%c", tr->name, 'a' + new->devnum);
270 		else
271 			snprintf(gd->disk_name, sizeof(gd->disk_name),
272 				 "%s%c%c", tr->name,
273 				 'a' - 1 + new->devnum / 26,
274 				 'a' + new->devnum % 26);
275 	else
276 		snprintf(gd->disk_name, sizeof(gd->disk_name),
277 			 "%s%d", tr->name, new->devnum);
278 
279 	/* 2.5 has capacity in units of 512 bytes while still
280 	   having BLOCK_SIZE_BITS set to 10. Just to keep us amused. */
281 	set_capacity(gd, (new->size * tr->blksize) >> 9);
282 
283 	gd->private_data = new;
284 	new->blkcore_priv = gd;
285 	gd->queue = tr->blkcore_priv->rq;
286 
287 	if (new->readonly)
288 		set_disk_ro(gd, 1);
289 
290 	add_disk(gd);
291 
292 	return 0;
293 }
294 
295 int del_mtd_blktrans_dev(struct mtd_blktrans_dev *old)
296 {
297 	if (mutex_trylock(&mtd_table_mutex)) {
298 		mutex_unlock(&mtd_table_mutex);
299 		BUG();
300 	}
301 
302 	list_del(&old->list);
303 
304 	del_gendisk(old->blkcore_priv);
305 	put_disk(old->blkcore_priv);
306 
307 	return 0;
308 }
309 
310 static void blktrans_notify_remove(struct mtd_info *mtd)
311 {
312 	struct list_head *this, *this2, *next;
313 
314 	list_for_each(this, &blktrans_majors) {
315 		struct mtd_blktrans_ops *tr = list_entry(this, struct mtd_blktrans_ops, list);
316 
317 		list_for_each_safe(this2, next, &tr->devs) {
318 			struct mtd_blktrans_dev *dev = list_entry(this2, struct mtd_blktrans_dev, list);
319 
320 			if (dev->mtd == mtd)
321 				tr->remove_dev(dev);
322 		}
323 	}
324 }
325 
326 static void blktrans_notify_add(struct mtd_info *mtd)
327 {
328 	struct list_head *this;
329 
330 	if (mtd->type == MTD_ABSENT)
331 		return;
332 
333 	list_for_each(this, &blktrans_majors) {
334 		struct mtd_blktrans_ops *tr = list_entry(this, struct mtd_blktrans_ops, list);
335 
336 		tr->add_mtd(tr, mtd);
337 	}
338 
339 }
340 
341 static struct mtd_notifier blktrans_notifier = {
342 	.add = blktrans_notify_add,
343 	.remove = blktrans_notify_remove,
344 };
345 
346 int register_mtd_blktrans(struct mtd_blktrans_ops *tr)
347 {
348 	int ret, i;
349 
350 	/* Register the notifier if/when the first device type is
351 	   registered, to prevent the link/init ordering from fucking
352 	   us over. */
353 	if (!blktrans_notifier.list.next)
354 		register_mtd_user(&blktrans_notifier);
355 
356 	tr->blkcore_priv = kzalloc(sizeof(*tr->blkcore_priv), GFP_KERNEL);
357 	if (!tr->blkcore_priv)
358 		return -ENOMEM;
359 
360 	mutex_lock(&mtd_table_mutex);
361 
362 	ret = register_blkdev(tr->major, tr->name);
363 	if (ret) {
364 		printk(KERN_WARNING "Unable to register %s block device on major %d: %d\n",
365 		       tr->name, tr->major, ret);
366 		kfree(tr->blkcore_priv);
367 		mutex_unlock(&mtd_table_mutex);
368 		return ret;
369 	}
370 	spin_lock_init(&tr->blkcore_priv->queue_lock);
371 
372 	tr->blkcore_priv->rq = blk_init_queue(mtd_blktrans_request, &tr->blkcore_priv->queue_lock);
373 	if (!tr->blkcore_priv->rq) {
374 		unregister_blkdev(tr->major, tr->name);
375 		kfree(tr->blkcore_priv);
376 		mutex_unlock(&mtd_table_mutex);
377 		return -ENOMEM;
378 	}
379 
380 	tr->blkcore_priv->rq->queuedata = tr;
381 	blk_queue_hardsect_size(tr->blkcore_priv->rq, tr->blksize);
382 	tr->blkshift = ffs(tr->blksize) - 1;
383 
384 	tr->blkcore_priv->thread = kthread_run(mtd_blktrans_thread, tr,
385 			"%sd", tr->name);
386 	if (IS_ERR(tr->blkcore_priv->thread)) {
387 		blk_cleanup_queue(tr->blkcore_priv->rq);
388 		unregister_blkdev(tr->major, tr->name);
389 		kfree(tr->blkcore_priv);
390 		mutex_unlock(&mtd_table_mutex);
391 		return PTR_ERR(tr->blkcore_priv->thread);
392 	}
393 
394 	INIT_LIST_HEAD(&tr->devs);
395 	list_add(&tr->list, &blktrans_majors);
396 
397 	for (i=0; i<MAX_MTD_DEVICES; i++) {
398 		if (mtd_table[i] && mtd_table[i]->type != MTD_ABSENT)
399 			tr->add_mtd(tr, mtd_table[i]);
400 	}
401 
402 	mutex_unlock(&mtd_table_mutex);
403 
404 	return 0;
405 }
406 
407 int deregister_mtd_blktrans(struct mtd_blktrans_ops *tr)
408 {
409 	struct list_head *this, *next;
410 
411 	mutex_lock(&mtd_table_mutex);
412 
413 	/* Clean up the kernel thread */
414 	kthread_stop(tr->blkcore_priv->thread);
415 
416 	/* Remove it from the list of active majors */
417 	list_del(&tr->list);
418 
419 	list_for_each_safe(this, next, &tr->devs) {
420 		struct mtd_blktrans_dev *dev = list_entry(this, struct mtd_blktrans_dev, list);
421 		tr->remove_dev(dev);
422 	}
423 
424 	blk_cleanup_queue(tr->blkcore_priv->rq);
425 	unregister_blkdev(tr->major, tr->name);
426 
427 	mutex_unlock(&mtd_table_mutex);
428 
429 	kfree(tr->blkcore_priv);
430 
431 	BUG_ON(!list_empty(&tr->devs));
432 	return 0;
433 }
434 
435 static void __exit mtd_blktrans_exit(void)
436 {
437 	/* No race here -- if someone's currently in register_mtd_blktrans
438 	   we're screwed anyway. */
439 	if (blktrans_notifier.list.next)
440 		unregister_mtd_user(&blktrans_notifier);
441 }
442 
443 module_exit(mtd_blktrans_exit);
444 
445 EXPORT_SYMBOL_GPL(register_mtd_blktrans);
446 EXPORT_SYMBOL_GPL(deregister_mtd_blktrans);
447 EXPORT_SYMBOL_GPL(add_mtd_blktrans_dev);
448 EXPORT_SYMBOL_GPL(del_mtd_blktrans_dev);
449 
450 MODULE_AUTHOR("David Woodhouse <dwmw2@infradead.org>");
451 MODULE_LICENSE("GPL");
452 MODULE_DESCRIPTION("Common interface to block layer for MTD 'translation layers'");
453