502622f628bc0dfb8e988a86833bc10dc5710c58
[linux-2.6.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 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 = blk_rq_pos(req) << 9 >> tr->blkshift;
51         nsect = blk_rq_cur_bytes(req) >> 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 -EIO;
61
62         if (blk_rq_pos(req) + blk_rq_cur_sectors(req) >
63             get_capacity(req->rq_disk))
64                 return -EIO;
65
66         switch(rq_data_dir(req)) {
67         case READ:
68                 for (; nsect > 0; nsect--, block++, buf += tr->blksize)
69                         if (tr->readsect(dev, block, buf))
70                                 return -EIO;
71                 return 0;
72
73         case WRITE:
74                 if (!tr->writesect)
75                         return -EIO;
76
77                 for (; nsect > 0; nsect--, block++, buf += tr->blksize)
78                         if (tr->writesect(dev, block, buf))
79                                 return -EIO;
80                 return 0;
81
82         default:
83                 printk(KERN_NOTICE "Unknown request %u\n", rq_data_dir(req));
84                 return -EIO;
85         }
86 }
87
88 static int mtd_blktrans_thread(void *arg)
89 {
90         struct mtd_blktrans_ops *tr = arg;
91         struct request_queue *rq = tr->blkcore_priv->rq;
92         struct request *req = NULL;
93
94         /* we might get involved when memory gets low, so use PF_MEMALLOC */
95         current->flags |= PF_MEMALLOC;
96
97         spin_lock_irq(rq->queue_lock);
98
99         while (!kthread_should_stop()) {
100                 struct mtd_blktrans_dev *dev;
101                 int res;
102
103                 if (!req && !(req = blk_fetch_request(rq))) {
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                 if (!__blk_end_request_cur(req, res))
123                         req = NULL;
124         }
125
126         if (req)
127                 __blk_end_request_all(req, -EIO);
128
129         spin_unlock_irq(rq->queue_lock);
130
131         return 0;
132 }
133
134 static void mtd_blktrans_request(struct request_queue *rq)
135 {
136         struct mtd_blktrans_ops *tr = rq->queuedata;
137         wake_up_process(tr->blkcore_priv->thread);
138 }
139
140
141 static int blktrans_open(struct block_device *bdev, fmode_t mode)
142 {
143         struct mtd_blktrans_dev *dev = bdev->bd_disk->private_data;
144         struct mtd_blktrans_ops *tr = dev->tr;
145         int ret = -ENODEV;
146
147         if (!try_module_get(dev->mtd->owner))
148                 goto out;
149
150         if (!try_module_get(tr->owner))
151                 goto out_tr;
152
153         /* FIXME: Locking. A hot pluggable device can go away
154            (del_mtd_device can be called for it) without its module
155            being unloaded. */
156         dev->mtd->usecount++;
157
158         ret = 0;
159         if (tr->open && (ret = tr->open(dev))) {
160                 dev->mtd->usecount--;
161                 module_put(dev->mtd->owner);
162         out_tr:
163                 module_put(tr->owner);
164         }
165  out:
166         return ret;
167 }
168
169 static int blktrans_release(struct gendisk *disk, fmode_t mode)
170 {
171         struct mtd_blktrans_dev *dev = disk->private_data;
172         struct mtd_blktrans_ops *tr = dev->tr;
173         int ret = 0;
174
175         if (tr->release)
176                 ret = tr->release(dev);
177
178         if (!ret) {
179                 dev->mtd->usecount--;
180                 module_put(dev->mtd->owner);
181                 module_put(tr->owner);
182         }
183
184         return ret;
185 }
186
187 static int blktrans_getgeo(struct block_device *bdev, struct hd_geometry *geo)
188 {
189         struct mtd_blktrans_dev *dev = bdev->bd_disk->private_data;
190
191         if (dev->tr->getgeo)
192                 return dev->tr->getgeo(dev, geo);
193         return -ENOTTY;
194 }
195
196 static int blktrans_ioctl(struct block_device *bdev, fmode_t mode,
197                               unsigned int cmd, unsigned long arg)
198 {
199         struct mtd_blktrans_dev *dev = bdev->bd_disk->private_data;
200         struct mtd_blktrans_ops *tr = dev->tr;
201
202         switch (cmd) {
203         case BLKFLSBUF:
204                 if (tr->flush)
205                         return tr->flush(dev);
206                 /* The core code did the work, we had nothing to do. */
207                 return 0;
208         default:
209                 return -ENOTTY;
210         }
211 }
212
213 static struct block_device_operations mtd_blktrans_ops = {
214         .owner          = THIS_MODULE,
215         .open           = blktrans_open,
216         .release        = blktrans_release,
217         .locked_ioctl   = blktrans_ioctl,
218         .getgeo         = blktrans_getgeo,
219 };
220
221 int add_mtd_blktrans_dev(struct mtd_blktrans_dev *new)
222 {
223         struct mtd_blktrans_ops *tr = new->tr;
224         struct mtd_blktrans_dev *d;
225         int last_devnum = -1;
226         struct gendisk *gd;
227
228         if (mutex_trylock(&mtd_table_mutex)) {
229                 mutex_unlock(&mtd_table_mutex);
230                 BUG();
231         }
232
233         list_for_each_entry(d, &tr->devs, list) {
234                 if (new->devnum == -1) {
235                         /* Use first free number */
236                         if (d->devnum != last_devnum+1) {
237                                 /* Found a free devnum. Plug it in here */
238                                 new->devnum = last_devnum+1;
239                                 list_add_tail(&new->list, &d->list);
240                                 goto added;
241                         }
242                 } else if (d->devnum == new->devnum) {
243                         /* Required number taken */
244                         return -EBUSY;
245                 } else if (d->devnum > new->devnum) {
246                         /* Required number was free */
247                         list_add_tail(&new->list, &d->list);
248                         goto added;
249                 }
250                 last_devnum = d->devnum;
251         }
252         if (new->devnum == -1)
253                 new->devnum = last_devnum+1;
254
255         if ((new->devnum << tr->part_bits) > 256) {
256                 return -EBUSY;
257         }
258
259         list_add_tail(&new->list, &tr->devs);
260  added:
261         mutex_init(&new->lock);
262         if (!tr->writesect)
263                 new->readonly = 1;
264
265         gd = alloc_disk(1 << tr->part_bits);
266         if (!gd) {
267                 list_del(&new->list);
268                 return -ENOMEM;
269         }
270         gd->major = tr->major;
271         gd->first_minor = (new->devnum) << tr->part_bits;
272         gd->fops = &mtd_blktrans_ops;
273
274         if (tr->part_bits)
275                 if (new->devnum < 26)
276                         snprintf(gd->disk_name, sizeof(gd->disk_name),
277                                  "%s%c", tr->name, 'a' + new->devnum);
278                 else
279                         snprintf(gd->disk_name, sizeof(gd->disk_name),
280                                  "%s%c%c", tr->name,
281                                  'a' - 1 + new->devnum / 26,
282                                  'a' + new->devnum % 26);
283         else
284                 snprintf(gd->disk_name, sizeof(gd->disk_name),
285                          "%s%d", tr->name, new->devnum);
286
287         /* 2.5 has capacity in units of 512 bytes while still
288            having BLOCK_SIZE_BITS set to 10. Just to keep us amused. */
289         set_capacity(gd, (new->size * tr->blksize) >> 9);
290
291         gd->private_data = new;
292         new->blkcore_priv = gd;
293         gd->queue = tr->blkcore_priv->rq;
294         gd->driverfs_dev = new->mtd->dev.parent;
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                 int ret = PTR_ERR(tr->blkcore_priv->thread);
392                 blk_cleanup_queue(tr->blkcore_priv->rq);
393                 unregister_blkdev(tr->major, tr->name);
394                 kfree(tr->blkcore_priv);
395                 mutex_unlock(&mtd_table_mutex);
396                 return ret;
397         }
398
399         INIT_LIST_HEAD(&tr->devs);
400         list_add(&tr->list, &blktrans_majors);
401
402         for (i=0; i<MAX_MTD_DEVICES; i++) {
403                 if (mtd_table[i] && mtd_table[i]->type != MTD_ABSENT)
404                         tr->add_mtd(tr, mtd_table[i]);
405         }
406
407         mutex_unlock(&mtd_table_mutex);
408
409         return 0;
410 }
411
412 int deregister_mtd_blktrans(struct mtd_blktrans_ops *tr)
413 {
414         struct mtd_blktrans_dev *dev, *next;
415
416         mutex_lock(&mtd_table_mutex);
417
418         /* Clean up the kernel thread */
419         kthread_stop(tr->blkcore_priv->thread);
420
421         /* Remove it from the list of active majors */
422         list_del(&tr->list);
423
424         list_for_each_entry_safe(dev, next, &tr->devs, list)
425                 tr->remove_dev(dev);
426
427         blk_cleanup_queue(tr->blkcore_priv->rq);
428         unregister_blkdev(tr->major, tr->name);
429
430         mutex_unlock(&mtd_table_mutex);
431
432         kfree(tr->blkcore_priv);
433
434         BUG_ON(!list_empty(&tr->devs));
435         return 0;
436 }
437
438 static void __exit mtd_blktrans_exit(void)
439 {
440         /* No race here -- if someone's currently in register_mtd_blktrans
441            we're screwed anyway. */
442         if (blktrans_notifier.list.next)
443                 unregister_mtd_user(&blktrans_notifier);
444 }
445
446 module_exit(mtd_blktrans_exit);
447
448 EXPORT_SYMBOL_GPL(register_mtd_blktrans);
449 EXPORT_SYMBOL_GPL(deregister_mtd_blktrans);
450 EXPORT_SYMBOL_GPL(add_mtd_blktrans_dev);
451 EXPORT_SYMBOL_GPL(del_mtd_blktrans_dev);
452
453 MODULE_AUTHOR("David Woodhouse <dwmw2@infradead.org>");
454 MODULE_LICENSE("GPL");
455 MODULE_DESCRIPTION("Common interface to block layer for MTD 'translation layers'");