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[linux-2.6] / drivers / mtd / mtd_blkdevs.c
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/spinlock.h>
20 #include <linux/hdreg.h>
21 #include <linux/init.h>
22 #include <linux/mutex.h>
23 #include <asm/uaccess.h>
24
25 static LIST_HEAD(blktrans_majors);
26
27 extern struct mutex mtd_table_mutex;
28 extern struct mtd_info *mtd_table[];
29
30 struct mtd_blkcore_priv {
31         struct completion thread_dead;
32         int exiting;
33         wait_queue_head_t thread_wq;
34         struct request_queue *rq;
35         spinlock_t queue_lock;
36 };
37
38 static int do_blktrans_request(struct mtd_blktrans_ops *tr,
39                                struct mtd_blktrans_dev *dev,
40                                struct request *req)
41 {
42         unsigned long block, nsect;
43         char *buf;
44
45         block = req->sector;
46         nsect = req->current_nr_sectors;
47         buf = req->buffer;
48
49         if (!(req->flags & REQ_CMD))
50                 return 0;
51
52         if (block + nsect > 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 += 512)
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 += 512)
67                         if (tr->writesect(dev, block, buf))
68                                 return 0;
69                 return 1;
70
71         default:
72                 printk(KERN_NOTICE "Unknown request %ld\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 | PF_NOFREEZE;
84
85         daemonize("%sd", tr->name);
86
87         /* daemonize() doesn't do this for us since some kernel threads
88            actually want to deal with signals. We can't just call
89            exit_sighand() since that'll cause an oops when we finally
90            do exit. */
91         spin_lock_irq(&current->sighand->siglock);
92         sigfillset(&current->blocked);
93         recalc_sigpending();
94         spin_unlock_irq(&current->sighand->siglock);
95
96         spin_lock_irq(rq->queue_lock);
97
98         while (!tr->blkcore_priv->exiting) {
99                 struct request *req;
100                 struct mtd_blktrans_dev *dev;
101                 int res = 0;
102                 DECLARE_WAITQUEUE(wait, current);
103
104                 req = elv_next_request(rq);
105
106                 if (!req) {
107                         add_wait_queue(&tr->blkcore_priv->thread_wq, &wait);
108                         set_current_state(TASK_INTERRUPTIBLE);
109
110                         spin_unlock_irq(rq->queue_lock);
111
112                         schedule();
113                         remove_wait_queue(&tr->blkcore_priv->thread_wq, &wait);
114
115                         spin_lock_irq(rq->queue_lock);
116
117                         continue;
118                 }
119
120                 dev = req->rq_disk->private_data;
121                 tr = dev->tr;
122
123                 spin_unlock_irq(rq->queue_lock);
124
125                 mutex_lock(&dev->lock);
126                 res = do_blktrans_request(tr, dev, req);
127                 mutex_unlock(&dev->lock);
128
129                 spin_lock_irq(rq->queue_lock);
130
131                 end_request(req, res);
132         }
133         spin_unlock_irq(rq->queue_lock);
134
135         complete_and_exit(&tr->blkcore_priv->thread_dead, 0);
136 }
137
138 static void mtd_blktrans_request(struct request_queue *rq)
139 {
140         struct mtd_blktrans_ops *tr = rq->queuedata;
141         wake_up(&tr->blkcore_priv->thread_wq);
142 }
143
144
145 static int blktrans_open(struct inode *i, struct file *f)
146 {
147         struct mtd_blktrans_dev *dev;
148         struct mtd_blktrans_ops *tr;
149         int ret = -ENODEV;
150
151         dev = i->i_bdev->bd_disk->private_data;
152         tr = dev->tr;
153
154         if (!try_module_get(dev->mtd->owner))
155                 goto out;
156
157         if (!try_module_get(tr->owner))
158                 goto out_tr;
159
160         /* FIXME: Locking. A hot pluggable device can go away
161            (del_mtd_device can be called for it) without its module
162            being unloaded. */
163         dev->mtd->usecount++;
164
165         ret = 0;
166         if (tr->open && (ret = tr->open(dev))) {
167                 dev->mtd->usecount--;
168                 module_put(dev->mtd->owner);
169         out_tr:
170                 module_put(tr->owner);
171         }
172  out:
173         return ret;
174 }
175
176 static int blktrans_release(struct inode *i, struct file *f)
177 {
178         struct mtd_blktrans_dev *dev;
179         struct mtd_blktrans_ops *tr;
180         int ret = 0;
181
182         dev = i->i_bdev->bd_disk->private_data;
183         tr = dev->tr;
184
185         if (tr->release)
186                 ret = tr->release(dev);
187
188         if (!ret) {
189                 dev->mtd->usecount--;
190                 module_put(dev->mtd->owner);
191                 module_put(tr->owner);
192         }
193
194         return ret;
195 }
196
197 static int blktrans_getgeo(struct block_device *bdev, struct hd_geometry *geo)
198 {
199         struct mtd_blktrans_dev *dev = bdev->bd_disk->private_data;
200
201         if (dev->tr->getgeo)
202                 return dev->tr->getgeo(dev, geo);
203         return -ENOTTY;
204 }
205
206 static int blktrans_ioctl(struct inode *inode, struct file *file,
207                               unsigned int cmd, unsigned long arg)
208 {
209         struct mtd_blktrans_dev *dev = inode->i_bdev->bd_disk->private_data;
210         struct mtd_blktrans_ops *tr = dev->tr;
211
212         switch (cmd) {
213         case BLKFLSBUF:
214                 if (tr->flush)
215                         return tr->flush(dev);
216                 /* The core code did the work, we had nothing to do. */
217                 return 0;
218         default:
219                 return -ENOTTY;
220         }
221 }
222
223 struct block_device_operations mtd_blktrans_ops = {
224         .owner          = THIS_MODULE,
225         .open           = blktrans_open,
226         .release        = blktrans_release,
227         .ioctl          = blktrans_ioctl,
228         .getgeo         = blktrans_getgeo,
229 };
230
231 int add_mtd_blktrans_dev(struct mtd_blktrans_dev *new)
232 {
233         struct mtd_blktrans_ops *tr = new->tr;
234         struct list_head *this;
235         int last_devnum = -1;
236         struct gendisk *gd;
237
238         if (!!mutex_trylock(&mtd_table_mutex)) {
239                 mutex_unlock(&mtd_table_mutex);
240                 BUG();
241         }
242
243         list_for_each(this, &tr->devs) {
244                 struct mtd_blktrans_dev *d = list_entry(this, struct mtd_blktrans_dev, list);
245                 if (new->devnum == -1) {
246                         /* Use first free number */
247                         if (d->devnum != last_devnum+1) {
248                                 /* Found a free devnum. Plug it in here */
249                                 new->devnum = last_devnum+1;
250                                 list_add_tail(&new->list, &d->list);
251                                 goto added;
252                         }
253                 } else if (d->devnum == new->devnum) {
254                         /* Required number taken */
255                         return -EBUSY;
256                 } else if (d->devnum > new->devnum) {
257                         /* Required number was free */
258                         list_add_tail(&new->list, &d->list);
259                         goto added;
260                 }
261                 last_devnum = d->devnum;
262         }
263         if (new->devnum == -1)
264                 new->devnum = last_devnum+1;
265
266         if ((new->devnum << tr->part_bits) > 256) {
267                 return -EBUSY;
268         }
269
270         mutex_init(&new->lock);
271         list_add_tail(&new->list, &tr->devs);
272  added:
273         if (!tr->writesect)
274                 new->readonly = 1;
275
276         gd = alloc_disk(1 << tr->part_bits);
277         if (!gd) {
278                 list_del(&new->list);
279                 return -ENOMEM;
280         }
281         gd->major = tr->major;
282         gd->first_minor = (new->devnum) << tr->part_bits;
283         gd->fops = &mtd_blktrans_ops;
284
285         if (tr->part_bits)
286                 if (new->devnum < 26)
287                         snprintf(gd->disk_name, sizeof(gd->disk_name),
288                                  "%s%c", tr->name, 'a' + new->devnum);
289                 else
290                         snprintf(gd->disk_name, sizeof(gd->disk_name),
291                                  "%s%c%c", tr->name,
292                                  'a' - 1 + new->devnum / 26,
293                                  'a' + new->devnum % 26);
294         else
295                 snprintf(gd->disk_name, sizeof(gd->disk_name),
296                          "%s%d", tr->name, new->devnum);
297
298         /* 2.5 has capacity in units of 512 bytes while still
299            having BLOCK_SIZE_BITS set to 10. Just to keep us amused. */
300         set_capacity(gd, (new->size * new->blksize) >> 9);
301
302         gd->private_data = new;
303         new->blkcore_priv = gd;
304         gd->queue = tr->blkcore_priv->rq;
305
306         if (new->readonly)
307                 set_disk_ro(gd, 1);
308
309         add_disk(gd);
310
311         return 0;
312 }
313
314 int del_mtd_blktrans_dev(struct mtd_blktrans_dev *old)
315 {
316         if (!!mutex_trylock(&mtd_table_mutex)) {
317                 mutex_unlock(&mtd_table_mutex);
318                 BUG();
319         }
320
321         list_del(&old->list);
322
323         del_gendisk(old->blkcore_priv);
324         put_disk(old->blkcore_priv);
325
326         return 0;
327 }
328
329 static void blktrans_notify_remove(struct mtd_info *mtd)
330 {
331         struct list_head *this, *this2, *next;
332
333         list_for_each(this, &blktrans_majors) {
334                 struct mtd_blktrans_ops *tr = list_entry(this, struct mtd_blktrans_ops, list);
335
336                 list_for_each_safe(this2, next, &tr->devs) {
337                         struct mtd_blktrans_dev *dev = list_entry(this2, struct mtd_blktrans_dev, list);
338
339                         if (dev->mtd == mtd)
340                                 tr->remove_dev(dev);
341                 }
342         }
343 }
344
345 static void blktrans_notify_add(struct mtd_info *mtd)
346 {
347         struct list_head *this;
348
349         if (mtd->type == MTD_ABSENT)
350                 return;
351
352         list_for_each(this, &blktrans_majors) {
353                 struct mtd_blktrans_ops *tr = list_entry(this, struct mtd_blktrans_ops, list);
354
355                 tr->add_mtd(tr, mtd);
356         }
357
358 }
359
360 static struct mtd_notifier blktrans_notifier = {
361         .add = blktrans_notify_add,
362         .remove = blktrans_notify_remove,
363 };
364
365 int register_mtd_blktrans(struct mtd_blktrans_ops *tr)
366 {
367         int ret, i;
368
369         /* Register the notifier if/when the first device type is
370            registered, to prevent the link/init ordering from fucking
371            us over. */
372         if (!blktrans_notifier.list.next)
373                 register_mtd_user(&blktrans_notifier);
374
375         tr->blkcore_priv = kmalloc(sizeof(*tr->blkcore_priv), GFP_KERNEL);
376         if (!tr->blkcore_priv)
377                 return -ENOMEM;
378
379         memset(tr->blkcore_priv, 0, sizeof(*tr->blkcore_priv));
380
381         mutex_lock(&mtd_table_mutex);
382
383         ret = register_blkdev(tr->major, tr->name);
384         if (ret) {
385                 printk(KERN_WARNING "Unable to register %s block device on major %d: %d\n",
386                        tr->name, tr->major, ret);
387                 kfree(tr->blkcore_priv);
388                 mutex_unlock(&mtd_table_mutex);
389                 return ret;
390         }
391         spin_lock_init(&tr->blkcore_priv->queue_lock);
392         init_completion(&tr->blkcore_priv->thread_dead);
393         init_waitqueue_head(&tr->blkcore_priv->thread_wq);
394
395         tr->blkcore_priv->rq = blk_init_queue(mtd_blktrans_request, &tr->blkcore_priv->queue_lock);
396         if (!tr->blkcore_priv->rq) {
397                 unregister_blkdev(tr->major, tr->name);
398                 kfree(tr->blkcore_priv);
399                 mutex_unlock(&mtd_table_mutex);
400                 return -ENOMEM;
401         }
402
403         tr->blkcore_priv->rq->queuedata = tr;
404
405         ret = kernel_thread(mtd_blktrans_thread, tr, CLONE_KERNEL);
406         if (ret < 0) {
407                 blk_cleanup_queue(tr->blkcore_priv->rq);
408                 unregister_blkdev(tr->major, tr->name);
409                 kfree(tr->blkcore_priv);
410                 mutex_unlock(&mtd_table_mutex);
411                 return ret;
412         }
413
414         INIT_LIST_HEAD(&tr->devs);
415         list_add(&tr->list, &blktrans_majors);
416
417         for (i=0; i<MAX_MTD_DEVICES; i++) {
418                 if (mtd_table[i] && mtd_table[i]->type != MTD_ABSENT)
419                         tr->add_mtd(tr, mtd_table[i]);
420         }
421
422         mutex_unlock(&mtd_table_mutex);
423
424         return 0;
425 }
426
427 int deregister_mtd_blktrans(struct mtd_blktrans_ops *tr)
428 {
429         struct list_head *this, *next;
430
431         mutex_lock(&mtd_table_mutex);
432
433         /* Clean up the kernel thread */
434         tr->blkcore_priv->exiting = 1;
435         wake_up(&tr->blkcore_priv->thread_wq);
436         wait_for_completion(&tr->blkcore_priv->thread_dead);
437
438         /* Remove it from the list of active majors */
439         list_del(&tr->list);
440
441         list_for_each_safe(this, next, &tr->devs) {
442                 struct mtd_blktrans_dev *dev = list_entry(this, struct mtd_blktrans_dev, list);
443                 tr->remove_dev(dev);
444         }
445
446         blk_cleanup_queue(tr->blkcore_priv->rq);
447         unregister_blkdev(tr->major, tr->name);
448
449         mutex_unlock(&mtd_table_mutex);
450
451         kfree(tr->blkcore_priv);
452
453         BUG_ON(!list_empty(&tr->devs));
454         return 0;
455 }
456
457 static void __exit mtd_blktrans_exit(void)
458 {
459         /* No race here -- if someone's currently in register_mtd_blktrans
460            we're screwed anyway. */
461         if (blktrans_notifier.list.next)
462                 unregister_mtd_user(&blktrans_notifier);
463 }
464
465 module_exit(mtd_blktrans_exit);
466
467 EXPORT_SYMBOL_GPL(register_mtd_blktrans);
468 EXPORT_SYMBOL_GPL(deregister_mtd_blktrans);
469 EXPORT_SYMBOL_GPL(add_mtd_blktrans_dev);
470 EXPORT_SYMBOL_GPL(del_mtd_blktrans_dev);
471
472 MODULE_AUTHOR("David Woodhouse <dwmw2@infradead.org>");
473 MODULE_LICENSE("GPL");
474 MODULE_DESCRIPTION("Common interface to block layer for MTD 'translation layers'");