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/spinlock.h>
  20 #include <linux/hdreg.h>
  21 #include <linux/init.h>
  22 #include <linux/mutex.h>
  23 #include <asm/uaccess.h>
  24
  25 static LIST_HEAD(blktrans_majors);
  26
  27 extern struct mutex 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 (!blk_fs_request(req))
  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 %u\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                 mutex_lock(&dev->lock);
 126                 res = do_blktrans_request(tr, dev, req);
 127                 mutex_unlock(&dev->lock);
 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 #if 0   // mask by Victor Yu. 02-12-2007
 152         dev = i->i_bdev->bd_disk->private_data;
 153 #else
 154         dev = i->u.i_bdev->bd_disk->private_data;
 155 #endif
 156         tr = dev->tr;
 157
 158         if (!try_module_get(dev->mtd->owner))
 159                 goto out;
 160
 161         if (!try_module_get(tr->owner))
 162                 goto out_tr;
 163
 164         /* FIXME: Locking. A hot pluggable device can go away
 165            (del_mtd_device can be called for it) without its module
 166            being unloaded. */
 167         dev->mtd->usecount++;
 168
 169         ret = 0;
 170         if (tr->open && (ret = tr->open(dev))) {
 171                 dev->mtd->usecount--;
 172                 module_put(dev->mtd->owner);
 173         out_tr:
 174                 module_put(tr->owner);
 175         }
 176  out:
 177         return ret;
 178 }
 179
 180 static int blktrans_release(struct inode *i, struct file *f)
 181 {
 182         struct mtd_blktrans_dev *dev;
 183         struct mtd_blktrans_ops *tr;
 184         int ret = 0;
 185
 186 #if 0   // mask by Victor Yu. 02-12-2007
 187         dev = i->i_bdev->bd_disk->private_data;
 188 #else
 189         dev = i->u.i_bdev->bd_disk->private_data;
 190 #endif
 191         tr = dev->tr;
 192
 193         if (tr->release)
 194                 ret = tr->release(dev);
 195
 196         if (!ret) {
 197                 dev->mtd->usecount--;
 198                 module_put(dev->mtd->owner);
 199                 module_put(tr->owner);
 200         }
 201
 202         return ret;
 203 }
 204
 205 static int blktrans_getgeo(struct block_device *bdev, struct hd_geometry *geo)
 206 {
 207         struct mtd_blktrans_dev *dev = bdev->bd_disk->private_data;
 208
 209         if (dev->tr->getgeo)
 210                 return dev->tr->getgeo(dev, geo);
 211         return -ENOTTY;
 212 }
 213
 214 static int blktrans_ioctl(struct inode *inode, struct file *file,
 215                               unsigned int cmd, unsigned long arg)
 216 {
 217 #if 0   // mask by Victor Yu. 02-12-2007
 218         struct mtd_blktrans_dev *dev = inode->i_bdev->bd_disk->private_data;
 219 #else
 220         struct mtd_blktrans_dev *dev = inode->u.i_bdev->bd_disk->private_data;
 221 #endif
 222         struct mtd_blktrans_ops *tr = dev->tr;
 223
 224         switch (cmd) {
 225         case BLKFLSBUF:
 226                 if (tr->flush)
 227                         return tr->flush(dev);
 228                 /* The core code did the work, we had nothing to do. */
 229                 return 0;
 230         default:
 231                 return -ENOTTY;
 232         }
 233 }
 234
 235 struct block_device_operations mtd_blktrans_ops = {
 236         .owner          = THIS_MODULE,
 237         .open           = blktrans_open,
 238         .release        = blktrans_release,
 239         .ioctl          = blktrans_ioctl,
 240         .getgeo         = blktrans_getgeo,
 241 };
 242
 243 int add_mtd_blktrans_dev(struct mtd_blktrans_dev *new)
 244 {
 245         struct mtd_blktrans_ops *tr = new->tr;
 246         struct list_head *this;
 247         int last_devnum = -1;
 248         struct gendisk *gd;
 249
 250         if (!!mutex_trylock(&mtd_table_mutex)) {
 251                 mutex_unlock(&mtd_table_mutex);
 252                 BUG();
 253         }
 254
 255         list_for_each(this, &tr->devs) {
 256                 struct mtd_blktrans_dev *d = list_entry(this, struct mtd_blktrans_dev, list);
 257                 if (new->devnum == -1) {
 258                         /* Use first free number */
 259                         if (d->devnum != last_devnum+1) {
 260                                 /* Found a free devnum. Plug it in here */
 261                                 new->devnum = last_devnum+1;
 262                                 list_add_tail(&new->list, &d->list);
 263                                 goto added;
 264                         }
 265                 } else if (d->devnum == new->devnum) {
 266                         /* Required number taken */
 267                         return -EBUSY;
 268                 } else if (d->devnum > new->devnum) {
 269                         /* Required number was free */
 270                         list_add_tail(&new->list, &d->list);
 271                         goto added;
 272                 }
 273                 last_devnum = d->devnum;
 274         }
 275         if (new->devnum == -1)
 276                 new->devnum = last_devnum+1;
 277
 278         if ((new->devnum << tr->part_bits) > 256) {
 279                 return -EBUSY;
 280         }
 281
 282         mutex_init(&new->lock);
 283         list_add_tail(&new->list, &tr->devs);
 284  added:
 285         if (!tr->writesect)
 286                 new->readonly = 1;
 287
 288         gd = alloc_disk(1 << tr->part_bits);
 289         if (!gd) {
 290                 list_del(&new->list);
 291                 return -ENOMEM;
 292         }
 293         gd->major = tr->major;
 294         gd->first_minor = (new->devnum) << tr->part_bits;
 295         gd->fops = &mtd_blktrans_ops;
 296
 297         if (tr->part_bits)
 298                 if (new->devnum < 26)
 299                         snprintf(gd->disk_name, sizeof(gd->disk_name),
 300                                  "%s%c", tr->name, 'a' + new->devnum);
 301                 else
 302                         snprintf(gd->disk_name, sizeof(gd->disk_name),
 303                                  "%s%c%c", tr->name,
 304                                  'a' - 1 + new->devnum / 26,
 305                                  'a' + new->devnum % 26);
 306         else
 307                 snprintf(gd->disk_name, sizeof(gd->disk_name),
 308                          "%s%d", tr->name, new->devnum);
 309
 310         /* 2.5 has capacity in units of 512 bytes while still
 311            having BLOCK_SIZE_BITS set to 10. Just to keep us amused. */
 312         set_capacity(gd, (new->size * new->blksize) >> 9);
 313
 314         gd->private_data = new;
 315         new->blkcore_priv = gd;
 316         gd->queue = tr->blkcore_priv->rq;
 317
 318         if (new->readonly)
 319                 set_disk_ro(gd, 1);
 320
 321         add_disk(gd);
 322
 323         return 0;
 324 }
 325
 326 int del_mtd_blktrans_dev(struct mtd_blktrans_dev *old)
 327 {
 328         if (!!mutex_trylock(&mtd_table_mutex)) {
 329                 mutex_unlock(&mtd_table_mutex);
 330                 BUG();
 331         }
 332
 333         list_del(&old->list);
 334
 335         del_gendisk(old->blkcore_priv);
 336         put_disk(old->blkcore_priv);
 337
 338         return 0;
 339 }
 340
 341 static void blktrans_notify_remove(struct mtd_info *mtd)
 342 {
 343         struct list_head *this, *this2, *next;
 344
 345         list_for_each(this, &blktrans_majors) {
 346                 struct mtd_blktrans_ops *tr = list_entry(this, struct mtd_blktrans_ops, list);
 347
 348                 list_for_each_safe(this2, next, &tr->devs) {
 349                         struct mtd_blktrans_dev *dev = list_entry(this2, struct mtd_blktrans_dev, list);
 350
 351                         if (dev->mtd == mtd)
 352                                 tr->remove_dev(dev);
 353                 }
 354         }
 355 }
 356
 357 static void blktrans_notify_add(struct mtd_info *mtd)
 358 {
 359         struct list_head *this;
 360
 361         if (mtd->type == MTD_ABSENT)
 362                 return;
 363
 364         list_for_each(this, &blktrans_majors) {
 365                 struct mtd_blktrans_ops *tr = list_entry(this, struct mtd_blktrans_ops, list);
 366
 367                 tr->add_mtd(tr, mtd);
 368         }
 369
 370 }
 371
 372 static struct mtd_notifier blktrans_notifier = {
 373         .add = blktrans_notify_add,
 374         .remove = blktrans_notify_remove,
 375 };
 376
 377 int register_mtd_blktrans(struct mtd_blktrans_ops *tr)
 378 {
 379         int ret, i;
 380
 381         /* Register the notifier if/when the first device type is
 382            registered, to prevent the link/init ordering from fucking
 383            us over. */
 384         if (!blktrans_notifier.list.next)
 385                 register_mtd_user(&blktrans_notifier);
 386
 387         tr->blkcore_priv = kmalloc(sizeof(*tr->blkcore_priv), GFP_KERNEL);
 388         if (!tr->blkcore_priv)
 389                 return -ENOMEM;
 390
 391         memset(tr->blkcore_priv, 0, sizeof(*tr->blkcore_priv));
 392
 393         mutex_lock(&mtd_table_mutex);
 394
 395         ret = register_blkdev(tr->major, tr->name);
 396         if (ret) {
 397                 printk(KERN_WARNING "Unable to register %s block device on major %d: %d\n",
 398                        tr->name, tr->major, ret);
 399                 kfree(tr->blkcore_priv);
 400                 mutex_unlock(&mtd_table_mutex);
 401                 return ret;
 402         }
 403         spin_lock_init(&tr->blkcore_priv->queue_lock);
 404         init_completion(&tr->blkcore_priv->thread_dead);
 405         init_waitqueue_head(&tr->blkcore_priv->thread_wq);
 406
 407         tr->blkcore_priv->rq = blk_init_queue(mtd_blktrans_request, &tr->blkcore_priv->queue_lock);
 408         if (!tr->blkcore_priv->rq) {
 409                 unregister_blkdev(tr->major, tr->name);
 410                 kfree(tr->blkcore_priv);
 411                 mutex_unlock(&mtd_table_mutex);
 412                 return -ENOMEM;
 413         }
 414
 415         tr->blkcore_priv->rq->queuedata = tr;
 416
 417         ret = kernel_thread(mtd_blktrans_thread, tr, CLONE_KERNEL);
 418         if (ret < 0) {
 419                 blk_cleanup_queue(tr->blkcore_priv->rq);
 420                 unregister_blkdev(tr->major, tr->name);
 421                 kfree(tr->blkcore_priv);
 422                 mutex_unlock(&mtd_table_mutex);
 423                 return ret;
 424         }
 425
 426         INIT_LIST_HEAD(&tr->devs);
 427         list_add(&tr->list, &blktrans_majors);
 428
 429         for (i=0; i<MAX_MTD_DEVICES; i++) {
 430                 if (mtd_table[i] && mtd_table[i]->type != MTD_ABSENT)
 431                         tr->add_mtd(tr, mtd_table[i]);
 432         }
 433
 434         mutex_unlock(&mtd_table_mutex);
 435
 436         return 0;
 437 }
 438
 439 int deregister_mtd_blktrans(struct mtd_blktrans_ops *tr)
 440 {
 441         struct list_head *this, *next;
 442
 443         mutex_lock(&mtd_table_mutex);
 444
 445         /* Clean up the kernel thread */
 446         tr->blkcore_priv->exiting = 1;
 447         wake_up(&tr->blkcore_priv->thread_wq);
 448         wait_for_completion(&tr->blkcore_priv->thread_dead);
 449
 450         /* Remove it from the list of active majors */
 451         list_del(&tr->list);
 452
 453         list_for_each_safe(this, next, &tr->devs) {
 454                 struct mtd_blktrans_dev *dev = list_entry(this, struct mtd_blktrans_dev, list);
 455                 tr->remove_dev(dev);
 456         }
 457
 458         blk_cleanup_queue(tr->blkcore_priv->rq);
 459         unregister_blkdev(tr->major, tr->name);
 460
 461         mutex_unlock(&mtd_table_mutex);
 462
 463         kfree(tr->blkcore_priv);
 464
 465         BUG_ON(!list_empty(&tr->devs));
 466         return 0;
 467 }
 468
 469 static void __exit mtd_blktrans_exit(void)
 470 {
 471         /* No race here -- if someone's currently in register_mtd_blktrans
 472            we're screwed anyway. */
 473         if (blktrans_notifier.list.next)
 474                 unregister_mtd_user(&blktrans_notifier);
 475 }
 476
 477 module_exit(mtd_blktrans_exit);
 478
 479 EXPORT_SYMBOL_GPL(register_mtd_blktrans);
 480 EXPORT_SYMBOL_GPL(deregister_mtd_blktrans);
 481 EXPORT_SYMBOL_GPL(add_mtd_blktrans_dev);
 482 EXPORT_SYMBOL_GPL(del_mtd_blktrans_dev);
 483
 484 MODULE_AUTHOR("David Woodhouse <dwmw2@infradead.org>");
 485 MODULE_LICENSE("GPL");
 486 MODULE_DESCRIPTION("Common interface to block layer for MTD 'translation layers'");