drivers/mtd/mtd_blkdevs.c

   1 /*
   2  * $Id: mtd_blkdevs.c,v 1.16 2003/06/23 13:34:43 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;
  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         complete_and_exit(&tr->blkcore_priv->thread_dead, 0);
 135 }
 136
 137 static void mtd_blktrans_request(struct request_queue *rq)
 138 {
 139         struct mtd_blktrans_ops *tr = rq->queuedata;
 140         wake_up(&tr->blkcore_priv->thread_wq);
 141 }
 142
 143
 144 int blktrans_open(struct inode *i, struct file *f)
 145 {
 146         struct mtd_blktrans_dev *dev;
 147         struct mtd_blktrans_ops *tr;
 148         int ret = -ENODEV;
 149
 150         dev = i->i_bdev->bd_disk->private_data;
 151         tr = dev->tr;
 152
 153         if (!try_module_get(dev->mtd->owner))
 154                 goto out;
 155
 156         if (!try_module_get(tr->owner))
 157                 goto out_tr;
 158
 159         /* FIXME: Locking. A hot pluggable device can go away
 160            (del_mtd_device can be called for it) without its module
 161            being unloaded. */
 162         dev->mtd->usecount++;
 163
 164         ret = 0;
 165         if (tr->open && (ret = tr->open(dev))) {
 166                 dev->mtd->usecount--;
 167                 module_put(dev->mtd->owner);
 168         out_tr:
 169                 module_put(tr->owner);
 170         }
 171  out:
 172         return ret;
 173 }
 174
 175 int blktrans_release(struct inode *i, struct file *f)
 176 {
 177         struct mtd_blktrans_dev *dev;
 178         struct mtd_blktrans_ops *tr;
 179         int ret = 0;
 180
 181         dev = i->i_bdev->bd_disk->private_data;
 182         tr = dev->tr;
 183
 184         if (tr->release)
 185                 ret = tr->release(dev);
 186
 187         if (!ret) {
 188                 dev->mtd->usecount--;
 189                 module_put(dev->mtd->owner);
 190                 module_put(tr->owner);
 191         }
 192
 193         return ret;
 194 }
 195
 196
 197 static int blktrans_ioctl(struct inode *inode, struct file *file,
 198                               unsigned int cmd, unsigned long arg)
 199 {
 200         struct mtd_blktrans_dev *dev = inode->i_bdev->bd_disk->private_data;
 201         struct mtd_blktrans_ops *tr = dev->tr;
 202
 203         switch (cmd) {
 204         case BLKFLSBUF:
 205                 if (tr->flush)
 206                         return tr->flush(dev);
 207                 /* The core code did the work, we had nothing to do. */
 208                 return 0;
 209
 210         case HDIO_GETGEO:
 211                 if (tr->getgeo) {
 212                         struct hd_geometry g;
 213                         int ret;
 214
 215                         memset(&g, 0, sizeof(g));
 216                         ret = tr->getgeo(dev, &g);
 217                         if (ret)
 218                                 return ret;
 219
 220                         g.start = get_start_sect(inode->i_bdev);
 221                         if (copy_to_user((void *)arg, &g, sizeof(g)))
 222                                 return -EFAULT;
 223                         return 0;
 224                 } /* else */
 225         default:
 226                 return -ENOTTY;
 227         }
 228 }
 229
 230 struct block_device_operations mtd_blktrans_ops = {
 231         .owner          = THIS_MODULE,
 232         .open           = blktrans_open,
 233         .release        = blktrans_release,
 234         .ioctl          = blktrans_ioctl,
 235 };
 236
 237 int add_mtd_blktrans_dev(struct mtd_blktrans_dev *new)
 238 {
 239         struct mtd_blktrans_ops *tr = new->tr;
 240         struct list_head *this;
 241         int last_devnum = -1;
 242         struct gendisk *gd;
 243
 244         if (!down_trylock(&mtd_table_mutex)) {
 245                 up(&mtd_table_mutex);
 246                 BUG();
 247         }
 248
 249         list_for_each(this, &tr->devs) {
 250                 struct mtd_blktrans_dev *d = list_entry(this, struct mtd_blktrans_dev, list);
 251                 if (new->devnum == -1) {
 252                         /* Use first free number */
 253                         if (d->devnum != last_devnum+1) {
 254                                 /* Found a free devnum. Plug it in here */
 255                                 new->devnum = last_devnum+1;
 256                                 list_add_tail(&new->list, &d->list);
 257                                 goto added;
 258                         }
 259                 } else if (d->devnum == new->devnum) {
 260                         /* Required number taken */
 261                         return -EBUSY;
 262                 } else if (d->devnum > new->devnum) {
 263                         /* Required number was free */
 264                         list_add_tail(&new->list, &d->list);
 265                         goto added;
 266                 }
 267                 last_devnum = d->devnum;
 268         }
 269         if (new->devnum == -1)
 270                 new->devnum = last_devnum+1;
 271
 272         if ((new->devnum << tr->part_bits) > 256) {
 273                 return -EBUSY;
 274         }
 275
 276         init_MUTEX(&new->sem);
 277         list_add_tail(&new->list, &tr->devs);
 278  added:
 279         if (!tr->writesect)
 280                 new->readonly = 1;
 281
 282         gd = alloc_disk(1 << tr->part_bits);
 283         if (!gd) {
 284                 list_del(&new->list);
 285                 return -ENOMEM;
 286         }
 287         gd->major = tr->major;
 288         gd->first_minor = (new->devnum) << tr->part_bits;
 289         gd->fops = &mtd_blktrans_ops;
 290
 291         snprintf(gd->disk_name, sizeof(gd->disk_name),
 292                  "%s%c", tr->name, (tr->part_bits?'a':'0') + new->devnum);
 293         snprintf(gd->devfs_name, sizeof(gd->devfs_name),
 294                  "%s/%c", tr->name, (tr->part_bits?'a':'0') + new->devnum);
 295
 296         set_capacity(gd, new->size);
 297         gd->private_data = new;
 298         new->blkcore_priv = gd;
 299         gd->queue = &tr->blkcore_priv->rq;
 300
 301         if (new->readonly)
 302                 set_disk_ro(gd, 1);
 303
 304         add_disk(gd);
 305
 306         return 0;
 307 }
 308
 309 int del_mtd_blktrans_dev(struct mtd_blktrans_dev *old)
 310 {
 311         if (!down_trylock(&mtd_table_mutex)) {
 312                 up(&mtd_table_mutex);
 313                 BUG();
 314         }
 315
 316         list_del(&old->list);
 317
 318         del_gendisk(old->blkcore_priv);
 319         put_disk(old->blkcore_priv);
 320
 321         return 0;
 322 }
 323
 324 void blktrans_notify_remove(struct mtd_info *mtd)
 325 {
 326         struct list_head *this, *this2, *next;
 327
 328         list_for_each(this, &blktrans_majors) {
 329                 struct mtd_blktrans_ops *tr = list_entry(this, struct mtd_blktrans_ops, list);
 330
 331                 list_for_each_safe(this2, next, &tr->devs) {
 332                         struct mtd_blktrans_dev *dev = list_entry(this2, struct mtd_blktrans_dev, list);
 333
 334                         if (dev->mtd == mtd)
 335                                 tr->remove_dev(dev);
 336                 }
 337         }
 338 }
 339
 340 void blktrans_notify_add(struct mtd_info *mtd)
 341 {
 342         struct list_head *this;
 343
 344         if (mtd->type == MTD_ABSENT)
 345                 return;
 346
 347         list_for_each(this, &blktrans_majors) {
 348                 struct mtd_blktrans_ops *tr = list_entry(this, struct mtd_blktrans_ops, list);
 349
 350                 tr->add_mtd(tr, mtd);
 351         }
 352
 353 }
 354
 355 static struct mtd_notifier blktrans_notifier = {
 356         .add = blktrans_notify_add,
 357         .remove = blktrans_notify_remove,
 358 };
 359
 360 int register_mtd_blktrans(struct mtd_blktrans_ops *tr)
 361 {
 362         int ret, i;
 363
 364         /* Register the notifier if/when the first device type is
 365            registered, to prevent the link/init ordering from fucking
 366            us over. */
 367         if (!blktrans_notifier.list.next)
 368                 register_mtd_user(&blktrans_notifier);
 369
 370         tr->blkcore_priv = kmalloc(sizeof(*tr->blkcore_priv), GFP_KERNEL);
 371         if (!tr->blkcore_priv)
 372                 return -ENOMEM;
 373
 374         memset(tr->blkcore_priv, 0, sizeof(*tr->blkcore_priv));
 375
 376         down(&mtd_table_mutex);
 377
 378         ret = register_blkdev(tr->major, tr->name);
 379         if (ret) {
 380                 printk(KERN_WARNING "Unable to register %s block device on major %d: %d\n",
 381                        tr->name, tr->major, ret);
 382                 kfree(tr->blkcore_priv);
 383                 up(&mtd_table_mutex);
 384                 return ret;
 385         }
 386         spin_lock_init(&tr->blkcore_priv->queue_lock);
 387         init_completion(&tr->blkcore_priv->thread_dead);
 388         init_waitqueue_head(&tr->blkcore_priv->thread_wq);
 389
 390         blk_init_queue(&tr->blkcore_priv->rq, mtd_blktrans_request,
 391                        &tr->blkcore_priv->queue_lock);
 392         tr->blkcore_priv->rq.queuedata = tr;
 393
 394         ret = kernel_thread(mtd_blktrans_thread, tr,
 395                             CLONE_FS|CLONE_FILES|CLONE_SIGHAND);
 396         if (ret < 0) {
 397                 blk_cleanup_queue(&tr->blkcore_priv->rq);
 398                 unregister_blkdev(tr->major, tr->name);
 399                 kfree(tr->blkcore_priv);
 400                 up(&mtd_table_mutex);
 401                 return ret;
 402         }
 403
 404         devfs_mk_dir(tr->name);
 405
 406         INIT_LIST_HEAD(&tr->devs);
 407         list_add(&tr->list, &blktrans_majors);
 408
 409         for (i=0; i<MAX_MTD_DEVICES; i++) {
 410                 if (mtd_table[i] && mtd_table[i]->type != MTD_ABSENT)
 411                         tr->add_mtd(tr, mtd_table[i]);
 412         }
 413
 414         up(&mtd_table_mutex);
 415
 416         return 0;
 417 }
 418
 419 int deregister_mtd_blktrans(struct mtd_blktrans_ops *tr)
 420 {
 421         struct list_head *this, *next;
 422
 423         down(&mtd_table_mutex);
 424
 425         /* Clean up the kernel thread */
 426         tr->blkcore_priv->exiting = 1;
 427         wake_up(&tr->blkcore_priv->thread_wq);
 428         wait_for_completion(&tr->blkcore_priv->thread_dead);
 429
 430         /* Remove it from the list of active majors */
 431         list_del(&tr->list);
 432
 433         list_for_each_safe(this, next, &tr->devs) {
 434                 struct mtd_blktrans_dev *dev = list_entry(this, struct mtd_blktrans_dev, list);
 435                 tr->remove_dev(dev);
 436         }
 437
 438         devfs_remove(tr->name);
 439         blk_cleanup_queue(&tr->blkcore_priv->rq);
 440         unregister_blkdev(tr->major, tr->name);
 441
 442         up(&mtd_table_mutex);
 443
 444         kfree(tr->blkcore_priv);
 445
 446         if (!list_empty(&tr->devs))
 447                 BUG();
 448         return 0;
 449 }
 450
 451 static void __exit mtd_blktrans_exit(void)
 452 {
 453         /* No race here -- if someone's currently in register_mtd_blktrans
 454            we're screwed anyway. */
 455         if (blktrans_notifier.list.next)
 456                 unregister_mtd_user(&blktrans_notifier);
 457 }
 458
 459 module_exit(mtd_blktrans_exit);
 460
 461 EXPORT_SYMBOL_GPL(register_mtd_blktrans);
 462 EXPORT_SYMBOL_GPL(deregister_mtd_blktrans);
 463 EXPORT_SYMBOL_GPL(add_mtd_blktrans_dev);
 464 EXPORT_SYMBOL_GPL(del_mtd_blktrans_dev);
 465
 466 MODULE_AUTHOR("David Woodhouse <dwmw2@infradead.org>");
 467 MODULE_LICENSE("GPL");
 468 MODULE_DESCRIPTION("Common interface to block layer for MTD 'translation layers'");