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[sfrench/cifs-2.6.git] / drivers / mtd / mtd_blkdevs.c
1 /*
2  * $Id: mtd_blkdevs.c,v 1.24 2004/11/16 18:28:59 dwmw2 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 <asm/semaphore.h>
23 #include <asm/uaccess.h>
24 #include <linux/devfs_fs_kernel.h>
25
26 static LIST_HEAD(blktrans_majors);
27
28 extern struct semaphore mtd_table_mutex;
29 extern struct mtd_info *mtd_table[];
30
31 struct mtd_blkcore_priv {
32         struct completion thread_dead;
33         int exiting;
34         wait_queue_head_t thread_wq;
35         struct request_queue *rq;
36         spinlock_t queue_lock;
37 };
38
39 static int do_blktrans_request(struct mtd_blktrans_ops *tr,
40                                struct mtd_blktrans_dev *dev,
41                                struct request *req)
42 {
43         unsigned long block, nsect;
44         char *buf;
45
46         block = req->sector;
47         nsect = req->current_nr_sectors;
48         buf = req->buffer;
49
50         if (!(req->flags & REQ_CMD))
51                 return 0;
52
53         if (block + nsect > get_capacity(req->rq_disk))
54                 return 0;
55
56         switch(rq_data_dir(req)) {
57         case READ:
58                 for (; nsect > 0; nsect--, block++, buf += 512)
59                         if (tr->readsect(dev, block, buf))
60                                 return 0;
61                 return 1;
62
63         case WRITE:
64                 if (!tr->writesect)
65                         return 0;
66
67                 for (; nsect > 0; nsect--, block++, buf += 512)
68                         if (tr->writesect(dev, block, buf))
69                                 return 0;
70                 return 1;
71
72         default:
73                 printk(KERN_NOTICE "Unknown request %ld\n", rq_data_dir(req));
74                 return 0;
75         }
76 }
77
78 static int mtd_blktrans_thread(void *arg)
79 {
80         struct mtd_blktrans_ops *tr = arg;
81         struct request_queue *rq = tr->blkcore_priv->rq;
82
83         /* we might get involved when memory gets low, so use PF_MEMALLOC */
84         current->flags |= PF_MEMALLOC | PF_NOFREEZE;
85
86         daemonize("%sd", tr->name);
87
88         /* daemonize() doesn't do this for us since some kernel threads
89            actually want to deal with signals. We can't just call 
90            exit_sighand() since that'll cause an oops when we finally
91            do exit. */
92         spin_lock_irq(&current->sighand->siglock);
93         sigfillset(&current->blocked);
94         recalc_sigpending();
95         spin_unlock_irq(&current->sighand->siglock);
96
97         spin_lock_irq(rq->queue_lock);
98                 
99         while (!tr->blkcore_priv->exiting) {
100                 struct request *req;
101                 struct mtd_blktrans_dev *dev;
102                 int res = 0;
103                 DECLARE_WAITQUEUE(wait, current);
104
105                 req = elv_next_request(rq);
106
107                 if (!req) {
108                         add_wait_queue(&tr->blkcore_priv->thread_wq, &wait);
109                         set_current_state(TASK_INTERRUPTIBLE);
110
111                         spin_unlock_irq(rq->queue_lock);
112
113                         schedule();
114                         remove_wait_queue(&tr->blkcore_priv->thread_wq, &wait);
115
116                         spin_lock_irq(rq->queue_lock);
117
118                         continue;
119                 }
120
121                 dev = req->rq_disk->private_data;
122                 tr = dev->tr;
123
124                 spin_unlock_irq(rq->queue_lock);
125
126                 down(&dev->sem);
127                 res = do_blktrans_request(tr, dev, req);
128                 up(&dev->sem);
129
130                 spin_lock_irq(rq->queue_lock);
131
132                 end_request(req, res);
133         }
134         spin_unlock_irq(rq->queue_lock);
135
136         complete_and_exit(&tr->blkcore_priv->thread_dead, 0);
137 }
138
139 static void mtd_blktrans_request(struct request_queue *rq)
140 {
141         struct mtd_blktrans_ops *tr = rq->queuedata;
142         wake_up(&tr->blkcore_priv->thread_wq);
143 }
144
145
146 static int blktrans_open(struct inode *i, struct file *f)
147 {
148         struct mtd_blktrans_dev *dev;
149         struct mtd_blktrans_ops *tr;
150         int ret = -ENODEV;
151
152         dev = i->i_bdev->bd_disk->private_data;
153         tr = dev->tr;
154
155         if (!try_module_get(dev->mtd->owner))
156                 goto out;
157
158         if (!try_module_get(tr->owner))
159                 goto out_tr;
160
161         /* FIXME: Locking. A hot pluggable device can go away 
162            (del_mtd_device can be called for it) without its module
163            being unloaded. */
164         dev->mtd->usecount++;
165
166         ret = 0;
167         if (tr->open && (ret = tr->open(dev))) {
168                 dev->mtd->usecount--;
169                 module_put(dev->mtd->owner);
170         out_tr:
171                 module_put(tr->owner);
172         }
173  out:
174         return ret;
175 }
176
177 static int blktrans_release(struct inode *i, struct file *f)
178 {
179         struct mtd_blktrans_dev *dev;
180         struct mtd_blktrans_ops *tr;
181         int ret = 0;
182
183         dev = i->i_bdev->bd_disk->private_data;
184         tr = dev->tr;
185
186         if (tr->release)
187                 ret = tr->release(dev);
188
189         if (!ret) {
190                 dev->mtd->usecount--;
191                 module_put(dev->mtd->owner);
192                 module_put(tr->owner);
193         }
194
195         return ret;
196 }
197
198
199 static int blktrans_ioctl(struct inode *inode, struct file *file, 
200                               unsigned int cmd, unsigned long arg)
201 {
202         struct mtd_blktrans_dev *dev = inode->i_bdev->bd_disk->private_data;
203         struct mtd_blktrans_ops *tr = dev->tr;
204
205         switch (cmd) {
206         case BLKFLSBUF:
207                 if (tr->flush)
208                         return tr->flush(dev);
209                 /* The core code did the work, we had nothing to do. */
210                 return 0;
211
212         case HDIO_GETGEO:
213                 if (tr->getgeo) {
214                         struct hd_geometry g;
215                         int ret;
216
217                         memset(&g, 0, sizeof(g));
218                         ret = tr->getgeo(dev, &g);
219                         if (ret)
220                                 return ret;
221
222                         g.start = get_start_sect(inode->i_bdev);
223                         if (copy_to_user((void __user *)arg, &g, sizeof(g)))
224                                 return -EFAULT;
225                         return 0;
226                 } /* else */
227         default:
228                 return -ENOTTY;
229         }
230 }
231
232 struct block_device_operations mtd_blktrans_ops = {
233         .owner          = THIS_MODULE,
234         .open           = blktrans_open,
235         .release        = blktrans_release,
236         .ioctl          = blktrans_ioctl,
237 };
238
239 int add_mtd_blktrans_dev(struct mtd_blktrans_dev *new)
240 {
241         struct mtd_blktrans_ops *tr = new->tr;
242         struct list_head *this;
243         int last_devnum = -1;
244         struct gendisk *gd;
245
246         if (!down_trylock(&mtd_table_mutex)) {
247                 up(&mtd_table_mutex);
248                 BUG();
249         }
250
251         list_for_each(this, &tr->devs) {
252                 struct mtd_blktrans_dev *d = list_entry(this, struct mtd_blktrans_dev, list);
253                 if (new->devnum == -1) {
254                         /* Use first free number */
255                         if (d->devnum != last_devnum+1) {
256                                 /* Found a free devnum. Plug it in here */
257                                 new->devnum = last_devnum+1;
258                                 list_add_tail(&new->list, &d->list);
259                                 goto added;
260                         }
261                 } else if (d->devnum == new->devnum) {
262                         /* Required number taken */
263                         return -EBUSY;
264                 } else if (d->devnum > new->devnum) {
265                         /* Required number was free */
266                         list_add_tail(&new->list, &d->list);
267                         goto added;
268                 } 
269                 last_devnum = d->devnum;
270         }
271         if (new->devnum == -1)
272                 new->devnum = last_devnum+1;
273
274         if ((new->devnum << tr->part_bits) > 256) {
275                 return -EBUSY;
276         }
277
278         init_MUTEX(&new->sem);
279         list_add_tail(&new->list, &tr->devs);
280  added:
281         if (!tr->writesect)
282                 new->readonly = 1;
283
284         gd = alloc_disk(1 << tr->part_bits);
285         if (!gd) {
286                 list_del(&new->list);
287                 return -ENOMEM;
288         }
289         gd->major = tr->major;
290         gd->first_minor = (new->devnum) << tr->part_bits;
291         gd->fops = &mtd_blktrans_ops;
292         
293         snprintf(gd->disk_name, sizeof(gd->disk_name),
294                  "%s%c", tr->name, (tr->part_bits?'a':'0') + new->devnum);
295         snprintf(gd->devfs_name, sizeof(gd->devfs_name),
296                  "%s/%c", tr->name, (tr->part_bits?'a':'0') + 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 (!down_trylock(&mtd_table_mutex)) {
317                 up(&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         down(&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                 up(&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                 up(&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                 up(&mtd_table_mutex);
411                 return ret;
412         } 
413
414         devfs_mk_dir(tr->name);
415
416         INIT_LIST_HEAD(&tr->devs);
417         list_add(&tr->list, &blktrans_majors);
418
419         for (i=0; i<MAX_MTD_DEVICES; i++) {
420                 if (mtd_table[i] && mtd_table[i]->type != MTD_ABSENT)
421                         tr->add_mtd(tr, mtd_table[i]);
422         }
423
424         up(&mtd_table_mutex);
425
426         return 0;
427 }
428
429 int deregister_mtd_blktrans(struct mtd_blktrans_ops *tr)
430 {
431         struct list_head *this, *next;
432
433         down(&mtd_table_mutex);
434
435         /* Clean up the kernel thread */
436         tr->blkcore_priv->exiting = 1;
437         wake_up(&tr->blkcore_priv->thread_wq);
438         wait_for_completion(&tr->blkcore_priv->thread_dead);
439
440         /* Remove it from the list of active majors */
441         list_del(&tr->list);
442
443         list_for_each_safe(this, next, &tr->devs) {
444                 struct mtd_blktrans_dev *dev = list_entry(this, struct mtd_blktrans_dev, list);
445                 tr->remove_dev(dev);
446         }
447
448         devfs_remove(tr->name);
449         blk_cleanup_queue(tr->blkcore_priv->rq);
450         unregister_blkdev(tr->major, tr->name);
451
452         up(&mtd_table_mutex);
453
454         kfree(tr->blkcore_priv);
455
456         if (!list_empty(&tr->devs))
457                 BUG();
458         return 0;
459 }
460
461 static void __exit mtd_blktrans_exit(void)
462 {
463         /* No race here -- if someone's currently in register_mtd_blktrans
464            we're screwed anyway. */
465         if (blktrans_notifier.list.next)
466                 unregister_mtd_user(&blktrans_notifier);
467 }
468
469 module_exit(mtd_blktrans_exit);
470
471 EXPORT_SYMBOL_GPL(register_mtd_blktrans);
472 EXPORT_SYMBOL_GPL(deregister_mtd_blktrans);
473 EXPORT_SYMBOL_GPL(add_mtd_blktrans_dev);
474 EXPORT_SYMBOL_GPL(del_mtd_blktrans_dev);
475
476 MODULE_AUTHOR("David Woodhouse <dwmw2@infradead.org>");
477 MODULE_LICENSE("GPL");
478 MODULE_DESCRIPTION("Common interface to block layer for MTD 'translation layers'");