drivers/mtd/mtd_blkdevs.c

   1 /*
   2  * $Id: mtd_blkdevs.c,v 1.25 2005/07/29 01:57:55 tpoynor 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
  25 static LIST_HEAD(blktrans_majors);
  26
  27 extern struct semaphore 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                 down(&dev->sem);
 126                 res = do_blktrans_request(tr, dev, req);
 127                 up(&dev->sem);
 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
 198 static int blktrans_ioctl(struct inode *inode, struct file *file,
 199                               unsigned int cmd, unsigned long arg)
 200 {
 201         struct mtd_blktrans_dev *dev = inode->i_bdev->bd_disk->private_data;
 202         struct mtd_blktrans_ops *tr = dev->tr;
 203
 204         switch (cmd) {
 205         case BLKFLSBUF:
 206                 if (tr->flush)
 207                         return tr->flush(dev);
 208                 /* The core code did the work, we had nothing to do. */
 209                 return 0;
 210
 211         case HDIO_GETGEO:
 212                 if (tr->getgeo) {
 213                         struct hd_geometry g;
 214                         int ret;
 215
 216                         memset(&g, 0, sizeof(g));
 217                         ret = tr->getgeo(dev, &g);
 218                         if (ret)
 219                                 return ret;
 220
 221                         g.start = get_start_sect(inode->i_bdev);
 222                         if (copy_to_user((void __user *)arg, &g, sizeof(g)))
 223                                 return -EFAULT;
 224                         return 0;
 225                 } /* else */
 226         default:
 227                 return -ENOTTY;
 228         }
 229 }
 230
 231 struct block_device_operations mtd_blktrans_ops = {
 232         .owner          = THIS_MODULE,
 233         .open           = blktrans_open,
 234         .release        = blktrans_release,
 235         .ioctl          = blktrans_ioctl,
 236 };
 237
 238 int add_mtd_blktrans_dev(struct mtd_blktrans_dev *new)
 239 {
 240         struct mtd_blktrans_ops *tr = new->tr;
 241         struct list_head *this;
 242         int last_devnum = -1;
 243         struct gendisk *gd;
 244
 245         if (!down_trylock(&mtd_table_mutex)) {
 246                 up(&mtd_table_mutex);
 247                 BUG();
 248         }
 249
 250         list_for_each(this, &tr->devs) {
 251                 struct mtd_blktrans_dev *d = list_entry(this, struct mtd_blktrans_dev, list);
 252                 if (new->devnum == -1) {
 253                         /* Use first free number */
 254                         if (d->devnum != last_devnum+1) {
 255                                 /* Found a free devnum. Plug it in here */
 256                                 new->devnum = last_devnum+1;
 257                                 list_add_tail(&new->list, &d->list);
 258                                 goto added;
 259                         }
 260                 } else if (d->devnum == new->devnum) {
 261                         /* Required number taken */
 262                         return -EBUSY;
 263                 } else if (d->devnum > new->devnum) {
 264                         /* Required number was free */
 265                         list_add_tail(&new->list, &d->list);
 266                         goto added;
 267                 }
 268                 last_devnum = d->devnum;
 269         }
 270         if (new->devnum == -1)
 271                 new->devnum = last_devnum+1;
 272
 273         if ((new->devnum << tr->part_bits) > 256) {
 274                 return -EBUSY;
 275         }
 276
 277         init_MUTEX(&new->sem);
 278         list_add_tail(&new->list, &tr->devs);
 279  added:
 280         if (!tr->writesect)
 281                 new->readonly = 1;
 282
 283         gd = alloc_disk(1 << tr->part_bits);
 284         if (!gd) {
 285                 list_del(&new->list);
 286                 return -ENOMEM;
 287         }
 288         gd->major = tr->major;
 289         gd->first_minor = (new->devnum) << tr->part_bits;
 290         gd->fops = &mtd_blktrans_ops;
 291
 292         snprintf(gd->disk_name, sizeof(gd->disk_name),
 293                  "%s%c", tr->name, (tr->part_bits?'a':'0') + new->devnum);
 294
 295         /* 2.5 has capacity in units of 512 bytes while still
 296            having BLOCK_SIZE_BITS set to 10. Just to keep us amused. */
 297         set_capacity(gd, (new->size * new->blksize) >> 9);
 298
 299         gd->private_data = new;
 300         new->blkcore_priv = gd;
 301         gd->queue = tr->blkcore_priv->rq;
 302
 303         if (new->readonly)
 304                 set_disk_ro(gd, 1);
 305
 306         add_disk(gd);
 307
 308         return 0;
 309 }
 310
 311 int del_mtd_blktrans_dev(struct mtd_blktrans_dev *old)
 312 {
 313         if (!down_trylock(&mtd_table_mutex)) {
 314                 up(&mtd_table_mutex);
 315                 BUG();
 316         }
 317
 318         list_del(&old->list);
 319
 320         del_gendisk(old->blkcore_priv);
 321         put_disk(old->blkcore_priv);
 322
 323         return 0;
 324 }
 325
 326 static void blktrans_notify_remove(struct mtd_info *mtd)
 327 {
 328         struct list_head *this, *this2, *next;
 329
 330         list_for_each(this, &blktrans_majors) {
 331                 struct mtd_blktrans_ops *tr = list_entry(this, struct mtd_blktrans_ops, list);
 332
 333                 list_for_each_safe(this2, next, &tr->devs) {
 334                         struct mtd_blktrans_dev *dev = list_entry(this2, struct mtd_blktrans_dev, list);
 335
 336                         if (dev->mtd == mtd)
 337                                 tr->remove_dev(dev);
 338                 }
 339         }
 340 }
 341
 342 static void blktrans_notify_add(struct mtd_info *mtd)
 343 {
 344         struct list_head *this;
 345
 346         if (mtd->type == MTD_ABSENT)
 347                 return;
 348
 349         list_for_each(this, &blktrans_majors) {
 350                 struct mtd_blktrans_ops *tr = list_entry(this, struct mtd_blktrans_ops, list);
 351
 352                 tr->add_mtd(tr, mtd);
 353         }
 354
 355 }
 356
 357 static struct mtd_notifier blktrans_notifier = {
 358         .add = blktrans_notify_add,
 359         .remove = blktrans_notify_remove,
 360 };
 361
 362 int register_mtd_blktrans(struct mtd_blktrans_ops *tr)
 363 {
 364         int ret, i;
 365
 366         /* Register the notifier if/when the first device type is
 367            registered, to prevent the link/init ordering from fucking
 368            us over. */
 369         if (!blktrans_notifier.list.next)
 370                 register_mtd_user(&blktrans_notifier);
 371
 372         tr->blkcore_priv = kmalloc(sizeof(*tr->blkcore_priv), GFP_KERNEL);
 373         if (!tr->blkcore_priv)
 374                 return -ENOMEM;
 375
 376         memset(tr->blkcore_priv, 0, sizeof(*tr->blkcore_priv));
 377
 378         down(&mtd_table_mutex);
 379
 380         ret = register_blkdev(tr->major, tr->name);
 381         if (ret) {
 382                 printk(KERN_WARNING "Unable to register %s block device on major %d: %d\n",
 383                        tr->name, tr->major, ret);
 384                 kfree(tr->blkcore_priv);
 385                 up(&mtd_table_mutex);
 386                 return ret;
 387         }
 388         spin_lock_init(&tr->blkcore_priv->queue_lock);
 389         init_completion(&tr->blkcore_priv->thread_dead);
 390         init_waitqueue_head(&tr->blkcore_priv->thread_wq);
 391
 392         tr->blkcore_priv->rq = blk_init_queue(mtd_blktrans_request, &tr->blkcore_priv->queue_lock);
 393         if (!tr->blkcore_priv->rq) {
 394                 unregister_blkdev(tr->major, tr->name);
 395                 kfree(tr->blkcore_priv);
 396                 up(&mtd_table_mutex);
 397                 return -ENOMEM;
 398         }
 399
 400         tr->blkcore_priv->rq->queuedata = tr;
 401
 402         ret = kernel_thread(mtd_blktrans_thread, tr, CLONE_KERNEL);
 403         if (ret < 0) {
 404                 blk_cleanup_queue(tr->blkcore_priv->rq);
 405                 unregister_blkdev(tr->major, tr->name);
 406                 kfree(tr->blkcore_priv);
 407                 up(&mtd_table_mutex);
 408                 return ret;
 409         }
 410
 411         INIT_LIST_HEAD(&tr->devs);
 412         list_add(&tr->list, &blktrans_majors);
 413
 414         for (i=0; i<MAX_MTD_DEVICES; i++) {
 415                 if (mtd_table[i] && mtd_table[i]->type != MTD_ABSENT)
 416                         tr->add_mtd(tr, mtd_table[i]);
 417         }
 418
 419         up(&mtd_table_mutex);
 420
 421         return 0;
 422 }
 423
 424 int deregister_mtd_blktrans(struct mtd_blktrans_ops *tr)
 425 {
 426         struct list_head *this, *next;
 427
 428         down(&mtd_table_mutex);
 429
 430         /* Clean up the kernel thread */
 431         tr->blkcore_priv->exiting = 1;
 432         wake_up(&tr->blkcore_priv->thread_wq);
 433         wait_for_completion(&tr->blkcore_priv->thread_dead);
 434
 435         /* Remove it from the list of active majors */
 436         list_del(&tr->list);
 437
 438         list_for_each_safe(this, next, &tr->devs) {
 439                 struct mtd_blktrans_dev *dev = list_entry(this, struct mtd_blktrans_dev, list);
 440                 tr->remove_dev(dev);
 441         }
 442
 443         blk_cleanup_queue(tr->blkcore_priv->rq);
 444         unregister_blkdev(tr->major, tr->name);
 445
 446         up(&mtd_table_mutex);
 447
 448         kfree(tr->blkcore_priv);
 449
 450         if (!list_empty(&tr->devs))
 451                 BUG();
 452         return 0;
 453 }
 454
 455 static void __exit mtd_blktrans_exit(void)
 456 {
 457         /* No race here -- if someone's currently in register_mtd_blktrans
 458            we're screwed anyway. */
 459         if (blktrans_notifier.list.next)
 460                 unregister_mtd_user(&blktrans_notifier);
 461 }
 462
 463 module_exit(mtd_blktrans_exit);
 464
 465 EXPORT_SYMBOL_GPL(register_mtd_blktrans);
 466 EXPORT_SYMBOL_GPL(deregister_mtd_blktrans);
 467 EXPORT_SYMBOL_GPL(add_mtd_blktrans_dev);
 468 EXPORT_SYMBOL_GPL(del_mtd_blktrans_dev);
 469
 470 MODULE_AUTHOR("David Woodhouse <dwmw2@infradead.org>");
 471 MODULE_LICENSE("GPL");
 472 MODULE_DESCRIPTION("Common interface to block layer for MTD 'translation layers'");