Merge git://git.infradead.org/mtd-2.6
[kernel.git] / drivers / mtd / mtd_blkdevs.c
1 /*
2  * (C) 2003 David Woodhouse <dwmw2@infradead.org>
3  *
4  * Interface to Linux 2.5 block layer for MTD 'translation layers'.
5  *
6  */
7
8 #include <linux/kernel.h>
9 #include <linux/slab.h>
10 #include <linux/module.h>
11 #include <linux/list.h>
12 #include <linux/fs.h>
13 #include <linux/mtd/blktrans.h>
14 #include <linux/mtd/mtd.h>
15 #include <linux/blkdev.h>
16 #include <linux/blkpg.h>
17 #include <linux/freezer.h>
18 #include <linux/spinlock.h>
19 #include <linux/hdreg.h>
20 #include <linux/init.h>
21 #include <linux/mutex.h>
22 #include <linux/kthread.h>
23 #include <asm/uaccess.h>
24
25 #include "mtdcore.h"
26
27 static LIST_HEAD(blktrans_majors);
28
29 struct mtd_blkcore_priv {
30         struct task_struct *thread;
31         struct request_queue *rq;
32         spinlock_t queue_lock;
33 };
34
35 static int do_blktrans_request(struct mtd_blktrans_ops *tr,
36                                struct mtd_blktrans_dev *dev,
37                                struct request *req)
38 {
39         unsigned long block, nsect;
40         char *buf;
41
42         block = blk_rq_pos(req) << 9 >> tr->blkshift;
43         nsect = blk_rq_cur_bytes(req) >> tr->blkshift;
44
45         buf = req->buffer;
46
47         if (!blk_fs_request(req))
48                 return -EIO;
49
50         if (blk_rq_pos(req) + blk_rq_cur_sectors(req) >
51             get_capacity(req->rq_disk))
52                 return -EIO;
53
54         if (blk_discard_rq(req))
55                 return tr->discard(dev, block, nsect);
56
57         switch(rq_data_dir(req)) {
58         case READ:
59                 for (; nsect > 0; nsect--, block++, buf += tr->blksize)
60                         if (tr->readsect(dev, block, buf))
61                                 return -EIO;
62                 rq_flush_dcache_pages(req);
63                 return 0;
64
65         case WRITE:
66                 if (!tr->writesect)
67                         return -EIO;
68
69                 rq_flush_dcache_pages(req);
70                 for (; nsect > 0; nsect--, block++, buf += tr->blksize)
71                         if (tr->writesect(dev, block, buf))
72                                 return -EIO;
73                 return 0;
74
75         default:
76                 printk(KERN_NOTICE "Unknown request %u\n", rq_data_dir(req));
77                 return -EIO;
78         }
79 }
80
81 static int mtd_blktrans_thread(void *arg)
82 {
83         struct mtd_blktrans_ops *tr = arg;
84         struct request_queue *rq = tr->blkcore_priv->rq;
85         struct request *req = NULL;
86
87         spin_lock_irq(rq->queue_lock);
88
89         while (!kthread_should_stop()) {
90                 struct mtd_blktrans_dev *dev;
91                 int res;
92
93                 if (!req && !(req = blk_fetch_request(rq))) {
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                 if (!__blk_end_request_cur(req, res))
113                         req = NULL;
114         }
115
116         if (req)
117                 __blk_end_request_all(req, -EIO);
118
119         spin_unlock_irq(rq->queue_lock);
120
121         return 0;
122 }
123
124 static void mtd_blktrans_request(struct request_queue *rq)
125 {
126         struct mtd_blktrans_ops *tr = rq->queuedata;
127         wake_up_process(tr->blkcore_priv->thread);
128 }
129
130
131 static int blktrans_open(struct block_device *bdev, fmode_t mode)
132 {
133         struct mtd_blktrans_dev *dev = bdev->bd_disk->private_data;
134         struct mtd_blktrans_ops *tr = dev->tr;
135         int ret = -ENODEV;
136
137         if (!get_mtd_device(NULL, dev->mtd->index))
138                 goto out;
139
140         if (!try_module_get(tr->owner))
141                 goto out_tr;
142
143         /* FIXME: Locking. A hot pluggable device can go away
144            (del_mtd_device can be called for it) without its module
145            being unloaded. */
146         dev->mtd->usecount++;
147
148         ret = 0;
149         if (tr->open && (ret = tr->open(dev))) {
150                 dev->mtd->usecount--;
151                 put_mtd_device(dev->mtd);
152         out_tr:
153                 module_put(tr->owner);
154         }
155  out:
156         return ret;
157 }
158
159 static int blktrans_release(struct gendisk *disk, fmode_t mode)
160 {
161         struct mtd_blktrans_dev *dev = disk->private_data;
162         struct mtd_blktrans_ops *tr = dev->tr;
163         int ret = 0;
164
165         if (tr->release)
166                 ret = tr->release(dev);
167
168         if (!ret) {
169                 dev->mtd->usecount--;
170                 put_mtd_device(dev->mtd);
171                 module_put(tr->owner);
172         }
173
174         return ret;
175 }
176
177 static int blktrans_getgeo(struct block_device *bdev, struct hd_geometry *geo)
178 {
179         struct mtd_blktrans_dev *dev = bdev->bd_disk->private_data;
180
181         if (dev->tr->getgeo)
182                 return dev->tr->getgeo(dev, geo);
183         return -ENOTTY;
184 }
185
186 static int blktrans_ioctl(struct block_device *bdev, fmode_t mode,
187                               unsigned int cmd, unsigned long arg)
188 {
189         struct mtd_blktrans_dev *dev = bdev->bd_disk->private_data;
190         struct mtd_blktrans_ops *tr = dev->tr;
191
192         switch (cmd) {
193         case BLKFLSBUF:
194                 if (tr->flush)
195                         return tr->flush(dev);
196                 /* The core code did the work, we had nothing to do. */
197                 return 0;
198         default:
199                 return -ENOTTY;
200         }
201 }
202
203 static const struct block_device_operations mtd_blktrans_ops = {
204         .owner          = THIS_MODULE,
205         .open           = blktrans_open,
206         .release        = blktrans_release,
207         .locked_ioctl   = blktrans_ioctl,
208         .getgeo         = blktrans_getgeo,
209 };
210
211 int add_mtd_blktrans_dev(struct mtd_blktrans_dev *new)
212 {
213         struct mtd_blktrans_ops *tr = new->tr;
214         struct mtd_blktrans_dev *d;
215         int last_devnum = -1;
216         struct gendisk *gd;
217
218         if (mutex_trylock(&mtd_table_mutex)) {
219                 mutex_unlock(&mtd_table_mutex);
220                 BUG();
221         }
222
223         list_for_each_entry(d, &tr->devs, list) {
224                 if (new->devnum == -1) {
225                         /* Use first free number */
226                         if (d->devnum != last_devnum+1) {
227                                 /* Found a free devnum. Plug it in here */
228                                 new->devnum = last_devnum+1;
229                                 list_add_tail(&new->list, &d->list);
230                                 goto added;
231                         }
232                 } else if (d->devnum == new->devnum) {
233                         /* Required number taken */
234                         return -EBUSY;
235                 } else if (d->devnum > new->devnum) {
236                         /* Required number was free */
237                         list_add_tail(&new->list, &d->list);
238                         goto added;
239                 }
240                 last_devnum = d->devnum;
241         }
242         if (new->devnum == -1)
243                 new->devnum = last_devnum+1;
244
245         if ((new->devnum << tr->part_bits) > 256) {
246                 return -EBUSY;
247         }
248
249         list_add_tail(&new->list, &tr->devs);
250  added:
251         mutex_init(&new->lock);
252         if (!tr->writesect)
253                 new->readonly = 1;
254
255         gd = alloc_disk(1 << tr->part_bits);
256         if (!gd) {
257                 list_del(&new->list);
258                 return -ENOMEM;
259         }
260         gd->major = tr->major;
261         gd->first_minor = (new->devnum) << tr->part_bits;
262         gd->fops = &mtd_blktrans_ops;
263
264         if (tr->part_bits)
265                 if (new->devnum < 26)
266                         snprintf(gd->disk_name, sizeof(gd->disk_name),
267                                  "%s%c", tr->name, 'a' + new->devnum);
268                 else
269                         snprintf(gd->disk_name, sizeof(gd->disk_name),
270                                  "%s%c%c", tr->name,
271                                  'a' - 1 + new->devnum / 26,
272                                  'a' + new->devnum % 26);
273         else
274                 snprintf(gd->disk_name, sizeof(gd->disk_name),
275                          "%s%d", tr->name, new->devnum);
276
277         /* 2.5 has capacity in units of 512 bytes while still
278            having BLOCK_SIZE_BITS set to 10. Just to keep us amused. */
279         set_capacity(gd, (new->size * tr->blksize) >> 9);
280
281         gd->private_data = new;
282         new->blkcore_priv = gd;
283         gd->queue = tr->blkcore_priv->rq;
284         gd->driverfs_dev = &new->mtd->dev;
285
286         if (new->readonly)
287                 set_disk_ro(gd, 1);
288
289         add_disk(gd);
290
291         return 0;
292 }
293
294 int del_mtd_blktrans_dev(struct mtd_blktrans_dev *old)
295 {
296         if (mutex_trylock(&mtd_table_mutex)) {
297                 mutex_unlock(&mtd_table_mutex);
298                 BUG();
299         }
300
301         list_del(&old->list);
302
303         del_gendisk(old->blkcore_priv);
304         put_disk(old->blkcore_priv);
305
306         return 0;
307 }
308
309 static void blktrans_notify_remove(struct mtd_info *mtd)
310 {
311         struct mtd_blktrans_ops *tr;
312         struct mtd_blktrans_dev *dev, *next;
313
314         list_for_each_entry(tr, &blktrans_majors, list)
315                 list_for_each_entry_safe(dev, next, &tr->devs, list)
316                         if (dev->mtd == mtd)
317                                 tr->remove_dev(dev);
318 }
319
320 static void blktrans_notify_add(struct mtd_info *mtd)
321 {
322         struct mtd_blktrans_ops *tr;
323
324         if (mtd->type == MTD_ABSENT)
325                 return;
326
327         list_for_each_entry(tr, &blktrans_majors, list)
328                 tr->add_mtd(tr, mtd);
329 }
330
331 static struct mtd_notifier blktrans_notifier = {
332         .add = blktrans_notify_add,
333         .remove = blktrans_notify_remove,
334 };
335
336 int register_mtd_blktrans(struct mtd_blktrans_ops *tr)
337 {
338         int ret, i;
339
340         /* Register the notifier if/when the first device type is
341            registered, to prevent the link/init ordering from fucking
342            us over. */
343         if (!blktrans_notifier.list.next)
344                 register_mtd_user(&blktrans_notifier);
345
346         tr->blkcore_priv = kzalloc(sizeof(*tr->blkcore_priv), GFP_KERNEL);
347         if (!tr->blkcore_priv)
348                 return -ENOMEM;
349
350         mutex_lock(&mtd_table_mutex);
351
352         ret = register_blkdev(tr->major, tr->name);
353         if (ret) {
354                 printk(KERN_WARNING "Unable to register %s block device on major %d: %d\n",
355                        tr->name, tr->major, ret);
356                 kfree(tr->blkcore_priv);
357                 mutex_unlock(&mtd_table_mutex);
358                 return ret;
359         }
360         spin_lock_init(&tr->blkcore_priv->queue_lock);
361
362         tr->blkcore_priv->rq = blk_init_queue(mtd_blktrans_request, &tr->blkcore_priv->queue_lock);
363         if (!tr->blkcore_priv->rq) {
364                 unregister_blkdev(tr->major, tr->name);
365                 kfree(tr->blkcore_priv);
366                 mutex_unlock(&mtd_table_mutex);
367                 return -ENOMEM;
368         }
369
370         tr->blkcore_priv->rq->queuedata = tr;
371         blk_queue_logical_block_size(tr->blkcore_priv->rq, tr->blksize);
372         if (tr->discard)
373                 queue_flag_set_unlocked(QUEUE_FLAG_DISCARD,
374                                         tr->blkcore_priv->rq);
375
376         tr->blkshift = ffs(tr->blksize) - 1;
377
378         tr->blkcore_priv->thread = kthread_run(mtd_blktrans_thread, tr,
379                         "%sd", tr->name);
380         if (IS_ERR(tr->blkcore_priv->thread)) {
381                 ret = PTR_ERR(tr->blkcore_priv->thread);
382                 blk_cleanup_queue(tr->blkcore_priv->rq);
383                 unregister_blkdev(tr->major, tr->name);
384                 kfree(tr->blkcore_priv);
385                 mutex_unlock(&mtd_table_mutex);
386                 return ret;
387         }
388
389         INIT_LIST_HEAD(&tr->devs);
390         list_add(&tr->list, &blktrans_majors);
391
392         for (i=0; i<MAX_MTD_DEVICES; i++) {
393                 if (mtd_table[i] && mtd_table[i]->type != MTD_ABSENT)
394                         tr->add_mtd(tr, mtd_table[i]);
395         }
396
397         mutex_unlock(&mtd_table_mutex);
398
399         return 0;
400 }
401
402 int deregister_mtd_blktrans(struct mtd_blktrans_ops *tr)
403 {
404         struct mtd_blktrans_dev *dev, *next;
405
406         mutex_lock(&mtd_table_mutex);
407
408         /* Clean up the kernel thread */
409         kthread_stop(tr->blkcore_priv->thread);
410
411         /* Remove it from the list of active majors */
412         list_del(&tr->list);
413
414         list_for_each_entry_safe(dev, next, &tr->devs, list)
415                 tr->remove_dev(dev);
416
417         blk_cleanup_queue(tr->blkcore_priv->rq);
418         unregister_blkdev(tr->major, tr->name);
419
420         mutex_unlock(&mtd_table_mutex);
421
422         kfree(tr->blkcore_priv);
423
424         BUG_ON(!list_empty(&tr->devs));
425         return 0;
426 }
427
428 static void __exit mtd_blktrans_exit(void)
429 {
430         /* No race here -- if someone's currently in register_mtd_blktrans
431            we're screwed anyway. */
432         if (blktrans_notifier.list.next)
433                 unregister_mtd_user(&blktrans_notifier);
434 }
435
436 module_exit(mtd_blktrans_exit);
437
438 EXPORT_SYMBOL_GPL(register_mtd_blktrans);
439 EXPORT_SYMBOL_GPL(deregister_mtd_blktrans);
440 EXPORT_SYMBOL_GPL(add_mtd_blktrans_dev);
441 EXPORT_SYMBOL_GPL(del_mtd_blktrans_dev);
442
443 MODULE_AUTHOR("David Woodhouse <dwmw2@infradead.org>");
444 MODULE_LICENSE("GPL");
445 MODULE_DESCRIPTION("Common interface to block layer for MTD 'translation layers'");