drivers/mtd/mtd_blkdevs.c

   1 /*
   2  * $Id: mtd_blkdevs.c,v 1.24 2004/11/16 18:28:59 dwmw2 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 #include <linux/devfs_fs_kernel.h>
  25
  26 static LIST_HEAD(blktrans_majors);
  27
  28 extern struct semaphore mtd_table_mutex;
  29 extern struct mtd_info *mtd_table[];
  30
  31 struct mtd_blkcore_priv {
  32         struct completion thread_dead;
  33         int exiting;
  34         wait_queue_head_t thread_wq;
  35         struct request_queue *rq;
  36         spinlock_t queue_lock;
  37 };
  38
  39 static int do_blktrans_request(struct mtd_blktrans_ops *tr,
  40                                struct mtd_blktrans_dev *dev,
  41                                struct request *req)
  42 {
  43         unsigned long block, nsect;
  44         char *buf;
  45
  46         block = req->sector;
  47         nsect = req->current_nr_sectors;
  48         buf = req->buffer;
  49
  50         if (!(req->flags & REQ_CMD))
  51                 return 0;
  52
  53         if (block + nsect > 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 += 512)
  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 += 512)
  68                         if (tr->writesect(dev, block, buf))
  69                                 return 0;
  70                 return 1;
  71
  72         default:
  73                 printk(KERN_NOTICE "Unknown request %ld\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 | PF_NOFREEZE;
  85
  86         daemonize("%sd", tr->name);
  87
  88         /* daemonize() doesn't do this for us since some kernel threads
  89            actually want to deal with signals. We can't just call
  90            exit_sighand() since that'll cause an oops when we finally
  91            do exit. */
  92         spin_lock_irq(&current->sighand->siglock);
  93         sigfillset(&current->blocked);
  94         recalc_sigpending();
  95         spin_unlock_irq(&current->sighand->siglock);
  96
  97         spin_lock_irq(rq->queue_lock);
  98
  99         while (!tr->blkcore_priv->exiting) {
 100                 struct request *req;
 101                 struct mtd_blktrans_dev *dev;
 102                 int res = 0;
 103                 DECLARE_WAITQUEUE(wait, current);
 104
 105                 req = elv_next_request(rq);
 106
 107                 if (!req) {
 108                         add_wait_queue(&tr->blkcore_priv->thread_wq, &wait);
 109                         set_current_state(TASK_INTERRUPTIBLE);
 110
 111                         spin_unlock_irq(rq->queue_lock);
 112
 113                         schedule();
 114                         remove_wait_queue(&tr->blkcore_priv->thread_wq, &wait);
 115
 116                         spin_lock_irq(rq->queue_lock);
 117
 118                         continue;
 119                 }
 120
 121                 dev = req->rq_disk->private_data;
 122                 tr = dev->tr;
 123
 124                 spin_unlock_irq(rq->queue_lock);
 125
 126                 down(&dev->sem);
 127                 res = do_blktrans_request(tr, dev, req);
 128                 up(&dev->sem);
 129
 130                 spin_lock_irq(rq->queue_lock);
 131
 132                 end_request(req, res);
 133         }
 134         spin_unlock_irq(rq->queue_lock);
 135
 136         complete_and_exit(&tr->blkcore_priv->thread_dead, 0);
 137 }
 138
 139 static void mtd_blktrans_request(struct request_queue *rq)
 140 {
 141         struct mtd_blktrans_ops *tr = rq->queuedata;
 142         wake_up(&tr->blkcore_priv->thread_wq);
 143 }
 144
 145
 146 static int blktrans_open(struct inode *i, struct file *f)
 147 {
 148         struct mtd_blktrans_dev *dev;
 149         struct mtd_blktrans_ops *tr;
 150         int ret = -ENODEV;
 151
 152         dev = i->i_bdev->bd_disk->private_data;
 153         tr = dev->tr;
 154
 155         if (!try_module_get(dev->mtd->owner))
 156                 goto out;
 157
 158         if (!try_module_get(tr->owner))
 159                 goto out_tr;
 160
 161         /* FIXME: Locking. A hot pluggable device can go away
 162            (del_mtd_device can be called for it) without its module
 163            being unloaded. */
 164         dev->mtd->usecount++;
 165
 166         ret = 0;
 167         if (tr->open && (ret = tr->open(dev))) {
 168                 dev->mtd->usecount--;
 169                 module_put(dev->mtd->owner);
 170         out_tr:
 171                 module_put(tr->owner);
 172         }
 173  out:
 174         return ret;
 175 }
 176
 177 static int blktrans_release(struct inode *i, struct file *f)
 178 {
 179         struct mtd_blktrans_dev *dev;
 180         struct mtd_blktrans_ops *tr;
 181         int ret = 0;
 182
 183         dev = i->i_bdev->bd_disk->private_data;
 184         tr = dev->tr;
 185
 186         if (tr->release)
 187                 ret = tr->release(dev);
 188
 189         if (!ret) {
 190                 dev->mtd->usecount--;
 191                 module_put(dev->mtd->owner);
 192                 module_put(tr->owner);
 193         }
 194
 195         return ret;
 196 }
 197
 198
 199 static int blktrans_ioctl(struct inode *inode, struct file *file,
 200                               unsigned int cmd, unsigned long arg)
 201 {
 202         struct mtd_blktrans_dev *dev = inode->i_bdev->bd_disk->private_data;
 203         struct mtd_blktrans_ops *tr = dev->tr;
 204
 205         switch (cmd) {
 206         case BLKFLSBUF:
 207                 if (tr->flush)
 208                         return tr->flush(dev);
 209                 /* The core code did the work, we had nothing to do. */
 210                 return 0;
 211
 212         case HDIO_GETGEO:
 213                 if (tr->getgeo) {
 214                         struct hd_geometry g;
 215                         int ret;
 216
 217                         memset(&g, 0, sizeof(g));
 218                         ret = tr->getgeo(dev, &g);
 219                         if (ret)
 220                                 return ret;
 221
 222                         g.start = get_start_sect(inode->i_bdev);
 223                         if (copy_to_user((void __user *)arg, &g, sizeof(g)))
 224                                 return -EFAULT;
 225                         return 0;
 226                 } /* else */
 227         default:
 228                 return -ENOTTY;
 229         }
 230 }
 231
 232 struct block_device_operations mtd_blktrans_ops = {
 233         .owner          = THIS_MODULE,
 234         .open           = blktrans_open,
 235         .release        = blktrans_release,
 236         .ioctl          = blktrans_ioctl,
 237 };
 238
 239 int add_mtd_blktrans_dev(struct mtd_blktrans_dev *new)
 240 {
 241         struct mtd_blktrans_ops *tr = new->tr;
 242         struct list_head *this;
 243         int last_devnum = -1;
 244         struct gendisk *gd;
 245
 246         if (!down_trylock(&mtd_table_mutex)) {
 247                 up(&mtd_table_mutex);
 248                 BUG();
 249         }
 250
 251         list_for_each(this, &tr->devs) {
 252                 struct mtd_blktrans_dev *d = list_entry(this, struct mtd_blktrans_dev, list);
 253                 if (new->devnum == -1) {
 254                         /* Use first free number */
 255                         if (d->devnum != last_devnum+1) {
 256                                 /* Found a free devnum. Plug it in here */
 257                                 new->devnum = last_devnum+1;
 258                                 list_add_tail(&new->list, &d->list);
 259                                 goto added;
 260                         }
 261                 } else if (d->devnum == new->devnum) {
 262                         /* Required number taken */
 263                         return -EBUSY;
 264                 } else if (d->devnum > new->devnum) {
 265                         /* Required number was free */
 266                         list_add_tail(&new->list, &d->list);
 267                         goto added;
 268                 }
 269                 last_devnum = d->devnum;
 270         }
 271         if (new->devnum == -1)
 272                 new->devnum = last_devnum+1;
 273
 274         if ((new->devnum << tr->part_bits) > 256) {
 275                 return -EBUSY;
 276         }
 277
 278         init_MUTEX(&new->sem);
 279         list_add_tail(&new->list, &tr->devs);
 280  added:
 281         if (!tr->writesect)
 282                 new->readonly = 1;
 283
 284         gd = alloc_disk(1 << tr->part_bits);
 285         if (!gd) {
 286                 list_del(&new->list);
 287                 return -ENOMEM;
 288         }
 289         gd->major = tr->major;
 290         gd->first_minor = (new->devnum) << tr->part_bits;
 291         gd->fops = &mtd_blktrans_ops;
 292
 293         snprintf(gd->disk_name, sizeof(gd->disk_name),
 294                  "%s%c", tr->name, (tr->part_bits?'a':'0') + new->devnum);
 295         snprintf(gd->devfs_name, sizeof(gd->devfs_name),
 296                  "%s/%c", tr->name, (tr->part_bits?'a':'0') + new->devnum);
 297
 298         /* 2.5 has capacity in units of 512 bytes while still
 299            having BLOCK_SIZE_BITS set to 10. Just to keep us amused. */
 300         set_capacity(gd, (new->size * new->blksize) >> 9);
 301
 302         gd->private_data = new;
 303         new->blkcore_priv = gd;
 304         gd->queue = tr->blkcore_priv->rq;
 305
 306         if (new->readonly)
 307                 set_disk_ro(gd, 1);
 308
 309         add_disk(gd);
 310
 311         return 0;
 312 }
 313
 314 int del_mtd_blktrans_dev(struct mtd_blktrans_dev *old)
 315 {
 316         if (!down_trylock(&mtd_table_mutex)) {
 317                 up(&mtd_table_mutex);
 318                 BUG();
 319         }
 320
 321         list_del(&old->list);
 322
 323         del_gendisk(old->blkcore_priv);
 324         put_disk(old->blkcore_priv);
 325
 326         return 0;
 327 }
 328
 329 static void blktrans_notify_remove(struct mtd_info *mtd)
 330 {
 331         struct list_head *this, *this2, *next;
 332
 333         list_for_each(this, &blktrans_majors) {
 334                 struct mtd_blktrans_ops *tr = list_entry(this, struct mtd_blktrans_ops, list);
 335
 336                 list_for_each_safe(this2, next, &tr->devs) {
 337                         struct mtd_blktrans_dev *dev = list_entry(this2, struct mtd_blktrans_dev, list);
 338
 339                         if (dev->mtd == mtd)
 340                                 tr->remove_dev(dev);
 341                 }
 342         }
 343 }
 344
 345 static void blktrans_notify_add(struct mtd_info *mtd)
 346 {
 347         struct list_head *this;
 348
 349         if (mtd->type == MTD_ABSENT)
 350                 return;
 351
 352         list_for_each(this, &blktrans_majors) {
 353                 struct mtd_blktrans_ops *tr = list_entry(this, struct mtd_blktrans_ops, list);
 354
 355                 tr->add_mtd(tr, mtd);
 356         }
 357
 358 }
 359
 360 static struct mtd_notifier blktrans_notifier = {
 361         .add = blktrans_notify_add,
 362         .remove = blktrans_notify_remove,
 363 };
 364
 365 int register_mtd_blktrans(struct mtd_blktrans_ops *tr)
 366 {
 367         int ret, i;
 368
 369         /* Register the notifier if/when the first device type is
 370            registered, to prevent the link/init ordering from fucking
 371            us over. */
 372         if (!blktrans_notifier.list.next)
 373                 register_mtd_user(&blktrans_notifier);
 374
 375         tr->blkcore_priv = kmalloc(sizeof(*tr->blkcore_priv), GFP_KERNEL);
 376         if (!tr->blkcore_priv)
 377                 return -ENOMEM;
 378
 379         memset(tr->blkcore_priv, 0, sizeof(*tr->blkcore_priv));
 380
 381         down(&mtd_table_mutex);
 382
 383         ret = register_blkdev(tr->major, tr->name);
 384         if (ret) {
 385                 printk(KERN_WARNING "Unable to register %s block device on major %d: %d\n",
 386                        tr->name, tr->major, ret);
 387                 kfree(tr->blkcore_priv);
 388                 up(&mtd_table_mutex);
 389                 return ret;
 390         }
 391         spin_lock_init(&tr->blkcore_priv->queue_lock);
 392         init_completion(&tr->blkcore_priv->thread_dead);
 393         init_waitqueue_head(&tr->blkcore_priv->thread_wq);
 394
 395         tr->blkcore_priv->rq = blk_init_queue(mtd_blktrans_request, &tr->blkcore_priv->queue_lock);
 396         if (!tr->blkcore_priv->rq) {
 397                 unregister_blkdev(tr->major, tr->name);
 398                 kfree(tr->blkcore_priv);
 399                 up(&mtd_table_mutex);
 400                 return -ENOMEM;
 401         }
 402
 403         tr->blkcore_priv->rq->queuedata = tr;
 404
 405         ret = kernel_thread(mtd_blktrans_thread, tr, CLONE_KERNEL);
 406         if (ret < 0) {
 407                 blk_cleanup_queue(tr->blkcore_priv->rq);
 408                 unregister_blkdev(tr->major, tr->name);
 409                 kfree(tr->blkcore_priv);
 410                 up(&mtd_table_mutex);
 411                 return ret;
 412         }
 413
 414         devfs_mk_dir(tr->name);
 415
 416         INIT_LIST_HEAD(&tr->devs);
 417         list_add(&tr->list, &blktrans_majors);
 418
 419         for (i=0; i<MAX_MTD_DEVICES; i++) {
 420                 if (mtd_table[i] && mtd_table[i]->type != MTD_ABSENT)
 421                         tr->add_mtd(tr, mtd_table[i]);
 422         }
 423
 424         up(&mtd_table_mutex);
 425
 426         return 0;
 427 }
 428
 429 int deregister_mtd_blktrans(struct mtd_blktrans_ops *tr)
 430 {
 431         struct list_head *this, *next;
 432
 433         down(&mtd_table_mutex);
 434
 435         /* Clean up the kernel thread */
 436         tr->blkcore_priv->exiting = 1;
 437         wake_up(&tr->blkcore_priv->thread_wq);
 438         wait_for_completion(&tr->blkcore_priv->thread_dead);
 439
 440         /* Remove it from the list of active majors */
 441         list_del(&tr->list);
 442
 443         list_for_each_safe(this, next, &tr->devs) {
 444                 struct mtd_blktrans_dev *dev = list_entry(this, struct mtd_blktrans_dev, list);
 445                 tr->remove_dev(dev);
 446         }
 447
 448         devfs_remove(tr->name);
 449         blk_cleanup_queue(tr->blkcore_priv->rq);
 450         unregister_blkdev(tr->major, tr->name);
 451
 452         up(&mtd_table_mutex);
 453
 454         kfree(tr->blkcore_priv);
 455
 456         if (!list_empty(&tr->devs))
 457                 BUG();
 458         return 0;
 459 }
 460
 461 static void __exit mtd_blktrans_exit(void)
 462 {
 463         /* No race here -- if someone's currently in register_mtd_blktrans
 464            we're screwed anyway. */
 465         if (blktrans_notifier.list.next)
 466                 unregister_mtd_user(&blktrans_notifier);
 467 }
 468
 469 module_exit(mtd_blktrans_exit);
 470
 471 EXPORT_SYMBOL_GPL(register_mtd_blktrans);
 472 EXPORT_SYMBOL_GPL(deregister_mtd_blktrans);
 473 EXPORT_SYMBOL_GPL(add_mtd_blktrans_dev);
 474 EXPORT_SYMBOL_GPL(del_mtd_blktrans_dev);
 475
 476 MODULE_AUTHOR("David Woodhouse <dwmw2@infradead.org>");
 477 MODULE_LICENSE("GPL");
 478 MODULE_DESCRIPTION("Common interface to block layer for MTD 'translation layers'");