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