Merge branch 'linus' into test
[linux-2.6] / 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 blktrans_discard_request(struct request_queue *q,
36                                     struct request *req)
37 {
38         req->cmd_type = REQ_TYPE_LINUX_BLOCK;
39         req->cmd[0] = REQ_LB_OP_DISCARD;
40         return 0;
41 }
42
43 static int do_blktrans_request(struct mtd_blktrans_ops *tr,
44                                struct mtd_blktrans_dev *dev,
45                                struct request *req)
46 {
47         unsigned long block, nsect;
48         char *buf;
49
50         block = req->sector << 9 >> tr->blkshift;
51         nsect = req->current_nr_sectors << 9 >> tr->blkshift;
52
53         buf = req->buffer;
54
55         if (req->cmd_type == REQ_TYPE_LINUX_BLOCK &&
56             req->cmd[0] == REQ_LB_OP_DISCARD)
57                 return !tr->discard(dev, block, nsect);
58
59         if (!blk_fs_request(req))
60                 return 0;
61
62         if (req->sector + req->current_nr_sectors > get_capacity(req->rq_disk))
63                 return 0;
64
65         switch(rq_data_dir(req)) {
66         case READ:
67                 for (; nsect > 0; nsect--, block++, buf += tr->blksize)
68                         if (tr->readsect(dev, block, buf))
69                                 return 0;
70                 return 1;
71
72         case WRITE:
73                 if (!tr->writesect)
74                         return 0;
75
76                 for (; nsect > 0; nsect--, block++, buf += tr->blksize)
77                         if (tr->writesect(dev, block, buf))
78                                 return 0;
79                 return 1;
80
81         default:
82                 printk(KERN_NOTICE "Unknown request %u\n", rq_data_dir(req));
83                 return 0;
84         }
85 }
86
87 static int mtd_blktrans_thread(void *arg)
88 {
89         struct mtd_blktrans_ops *tr = arg;
90         struct request_queue *rq = tr->blkcore_priv->rq;
91
92         /* we might get involved when memory gets low, so use PF_MEMALLOC */
93         current->flags |= PF_MEMALLOC;
94
95         spin_lock_irq(rq->queue_lock);
96         while (!kthread_should_stop()) {
97                 struct request *req;
98                 struct mtd_blktrans_dev *dev;
99                 int res = 0;
100
101                 req = elv_next_request(rq);
102
103                 if (!req) {
104                         set_current_state(TASK_INTERRUPTIBLE);
105                         spin_unlock_irq(rq->queue_lock);
106                         schedule();
107                         spin_lock_irq(rq->queue_lock);
108                         continue;
109                 }
110
111                 dev = req->rq_disk->private_data;
112                 tr = dev->tr;
113
114                 spin_unlock_irq(rq->queue_lock);
115
116                 mutex_lock(&dev->lock);
117                 res = do_blktrans_request(tr, dev, req);
118                 mutex_unlock(&dev->lock);
119
120                 spin_lock_irq(rq->queue_lock);
121
122                 end_request(req, res);
123         }
124         spin_unlock_irq(rq->queue_lock);
125
126         return 0;
127 }
128
129 static void mtd_blktrans_request(struct request_queue *rq)
130 {
131         struct mtd_blktrans_ops *tr = rq->queuedata;
132         wake_up_process(tr->blkcore_priv->thread);
133 }
134
135
136 static int blktrans_open(struct inode *i, struct file *f)
137 {
138         struct mtd_blktrans_dev *dev;
139         struct mtd_blktrans_ops *tr;
140         int ret = -ENODEV;
141
142         dev = i->i_bdev->bd_disk->private_data;
143         tr = dev->tr;
144
145         if (!try_module_get(dev->mtd->owner))
146                 goto out;
147
148         if (!try_module_get(tr->owner))
149                 goto out_tr;
150
151         /* FIXME: Locking. A hot pluggable device can go away
152            (del_mtd_device can be called for it) without its module
153            being unloaded. */
154         dev->mtd->usecount++;
155
156         ret = 0;
157         if (tr->open && (ret = tr->open(dev))) {
158                 dev->mtd->usecount--;
159                 module_put(dev->mtd->owner);
160         out_tr:
161                 module_put(tr->owner);
162         }
163  out:
164         return ret;
165 }
166
167 static int blktrans_release(struct inode *i, struct file *f)
168 {
169         struct mtd_blktrans_dev *dev;
170         struct mtd_blktrans_ops *tr;
171         int ret = 0;
172
173         dev = i->i_bdev->bd_disk->private_data;
174         tr = dev->tr;
175
176         if (tr->release)
177                 ret = tr->release(dev);
178
179         if (!ret) {
180                 dev->mtd->usecount--;
181                 module_put(dev->mtd->owner);
182                 module_put(tr->owner);
183         }
184
185         return ret;
186 }
187
188 static int blktrans_getgeo(struct block_device *bdev, struct hd_geometry *geo)
189 {
190         struct mtd_blktrans_dev *dev = bdev->bd_disk->private_data;
191
192         if (dev->tr->getgeo)
193                 return dev->tr->getgeo(dev, geo);
194         return -ENOTTY;
195 }
196
197 static int blktrans_ioctl(struct inode *inode, struct file *file,
198                               unsigned int cmd, unsigned long arg)
199 {
200         struct mtd_blktrans_dev *dev = inode->i_bdev->bd_disk->private_data;
201         struct mtd_blktrans_ops *tr = dev->tr;
202
203         switch (cmd) {
204         case BLKFLSBUF:
205                 if (tr->flush)
206                         return tr->flush(dev);
207                 /* The core code did the work, we had nothing to do. */
208                 return 0;
209         default:
210                 return -ENOTTY;
211         }
212 }
213
214 static struct block_device_operations mtd_blktrans_ops = {
215         .owner          = THIS_MODULE,
216         .open           = blktrans_open,
217         .release        = blktrans_release,
218         .ioctl          = blktrans_ioctl,
219         .getgeo         = blktrans_getgeo,
220 };
221
222 int add_mtd_blktrans_dev(struct mtd_blktrans_dev *new)
223 {
224         struct mtd_blktrans_ops *tr = new->tr;
225         struct mtd_blktrans_dev *d;
226         int last_devnum = -1;
227         struct gendisk *gd;
228
229         if (mutex_trylock(&mtd_table_mutex)) {
230                 mutex_unlock(&mtd_table_mutex);
231                 BUG();
232         }
233
234         list_for_each_entry(d, &tr->devs, list) {
235                 if (new->devnum == -1) {
236                         /* Use first free number */
237                         if (d->devnum != last_devnum+1) {
238                                 /* Found a free devnum. Plug it in here */
239                                 new->devnum = last_devnum+1;
240                                 list_add_tail(&new->list, &d->list);
241                                 goto added;
242                         }
243                 } else if (d->devnum == new->devnum) {
244                         /* Required number taken */
245                         return -EBUSY;
246                 } else if (d->devnum > new->devnum) {
247                         /* Required number was free */
248                         list_add_tail(&new->list, &d->list);
249                         goto added;
250                 }
251                 last_devnum = d->devnum;
252         }
253         if (new->devnum == -1)
254                 new->devnum = last_devnum+1;
255
256         if ((new->devnum << tr->part_bits) > 256) {
257                 return -EBUSY;
258         }
259
260         list_add_tail(&new->list, &tr->devs);
261  added:
262         mutex_init(&new->lock);
263         if (!tr->writesect)
264                 new->readonly = 1;
265
266         gd = alloc_disk(1 << tr->part_bits);
267         if (!gd) {
268                 list_del(&new->list);
269                 return -ENOMEM;
270         }
271         gd->major = tr->major;
272         gd->first_minor = (new->devnum) << tr->part_bits;
273         gd->fops = &mtd_blktrans_ops;
274
275         if (tr->part_bits)
276                 if (new->devnum < 26)
277                         snprintf(gd->disk_name, sizeof(gd->disk_name),
278                                  "%s%c", tr->name, 'a' + new->devnum);
279                 else
280                         snprintf(gd->disk_name, sizeof(gd->disk_name),
281                                  "%s%c%c", tr->name,
282                                  'a' - 1 + new->devnum / 26,
283                                  'a' + new->devnum % 26);
284         else
285                 snprintf(gd->disk_name, sizeof(gd->disk_name),
286                          "%s%d", tr->name, new->devnum);
287
288         /* 2.5 has capacity in units of 512 bytes while still
289            having BLOCK_SIZE_BITS set to 10. Just to keep us amused. */
290         set_capacity(gd, (new->size * tr->blksize) >> 9);
291
292         gd->private_data = new;
293         new->blkcore_priv = gd;
294         gd->queue = tr->blkcore_priv->rq;
295
296         if (new->readonly)
297                 set_disk_ro(gd, 1);
298
299         add_disk(gd);
300
301         return 0;
302 }
303
304 int del_mtd_blktrans_dev(struct mtd_blktrans_dev *old)
305 {
306         if (mutex_trylock(&mtd_table_mutex)) {
307                 mutex_unlock(&mtd_table_mutex);
308                 BUG();
309         }
310
311         list_del(&old->list);
312
313         del_gendisk(old->blkcore_priv);
314         put_disk(old->blkcore_priv);
315
316         return 0;
317 }
318
319 static void blktrans_notify_remove(struct mtd_info *mtd)
320 {
321         struct mtd_blktrans_ops *tr;
322         struct mtd_blktrans_dev *dev, *next;
323
324         list_for_each_entry(tr, &blktrans_majors, list)
325                 list_for_each_entry_safe(dev, next, &tr->devs, list)
326                         if (dev->mtd == mtd)
327                                 tr->remove_dev(dev);
328 }
329
330 static void blktrans_notify_add(struct mtd_info *mtd)
331 {
332         struct mtd_blktrans_ops *tr;
333
334         if (mtd->type == MTD_ABSENT)
335                 return;
336
337         list_for_each_entry(tr, &blktrans_majors, list)
338                 tr->add_mtd(tr, mtd);
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         if (tr->discard)
383                 blk_queue_set_discard(tr->blkcore_priv->rq,
384                                       blktrans_discard_request);
385
386         tr->blkshift = ffs(tr->blksize) - 1;
387
388         tr->blkcore_priv->thread = kthread_run(mtd_blktrans_thread, tr,
389                         "%sd", tr->name);
390         if (IS_ERR(tr->blkcore_priv->thread)) {
391                 blk_cleanup_queue(tr->blkcore_priv->rq);
392                 unregister_blkdev(tr->major, tr->name);
393                 kfree(tr->blkcore_priv);
394                 mutex_unlock(&mtd_table_mutex);
395                 return PTR_ERR(tr->blkcore_priv->thread);
396         }
397
398         INIT_LIST_HEAD(&tr->devs);
399         list_add(&tr->list, &blktrans_majors);
400
401         for (i=0; i<MAX_MTD_DEVICES; i++) {
402                 if (mtd_table[i] && mtd_table[i]->type != MTD_ABSENT)
403                         tr->add_mtd(tr, mtd_table[i]);
404         }
405
406         mutex_unlock(&mtd_table_mutex);
407
408         return 0;
409 }
410
411 int deregister_mtd_blktrans(struct mtd_blktrans_ops *tr)
412 {
413         struct mtd_blktrans_dev *dev, *next;
414
415         mutex_lock(&mtd_table_mutex);
416
417         /* Clean up the kernel thread */
418         kthread_stop(tr->blkcore_priv->thread);
419
420         /* Remove it from the list of active majors */
421         list_del(&tr->list);
422
423         list_for_each_entry_safe(dev, next, &tr->devs, list)
424                 tr->remove_dev(dev);
425
426         blk_cleanup_queue(tr->blkcore_priv->rq);
427         unregister_blkdev(tr->major, tr->name);
428
429         mutex_unlock(&mtd_table_mutex);
430
431         kfree(tr->blkcore_priv);
432
433         BUG_ON(!list_empty(&tr->devs));
434         return 0;
435 }
436
437 static void __exit mtd_blktrans_exit(void)
438 {
439         /* No race here -- if someone's currently in register_mtd_blktrans
440            we're screwed anyway. */
441         if (blktrans_notifier.list.next)
442                 unregister_mtd_user(&blktrans_notifier);
443 }
444
445 module_exit(mtd_blktrans_exit);
446
447 EXPORT_SYMBOL_GPL(register_mtd_blktrans);
448 EXPORT_SYMBOL_GPL(deregister_mtd_blktrans);
449 EXPORT_SYMBOL_GPL(add_mtd_blktrans_dev);
450 EXPORT_SYMBOL_GPL(del_mtd_blktrans_dev);
451
452 MODULE_AUTHOR("David Woodhouse <dwmw2@infradead.org>");
453 MODULE_LICENSE("GPL");
454 MODULE_DESCRIPTION("Common interface to block layer for MTD 'translation layers'");