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 <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 static int blktrans_getgeo(struct block_device *bdev, struct hd_geometry *geo)
 198 {
 199         struct mtd_blktrans_dev *dev = bdev->bd_disk->private_data;
 200
 201         if (dev->tr->getgeo)
 202                 return dev->tr->getgeo(dev, geo);
 203         return -ENOTTY;
 204 }
 205
 206 static int blktrans_ioctl(struct inode *inode, struct file *file,
 207                               unsigned int cmd, unsigned long arg)
 208 {
 209         struct mtd_blktrans_dev *dev = inode->i_bdev->bd_disk->private_data;
 210         struct mtd_blktrans_ops *tr = dev->tr;
 211
 212         switch (cmd) {
 213         case BLKFLSBUF:
 214                 if (tr->flush)
 215                         return tr->flush(dev);
 216                 /* The core code did the work, we had nothing to do. */
 217                 return 0;
 218         default:
 219                 return -ENOTTY;
 220         }
 221 }
 222
 223 struct block_device_operations mtd_blktrans_ops = {
 224         .owner          = THIS_MODULE,
 225         .open           = blktrans_open,
 226         .release        = blktrans_release,
 227         .ioctl          = blktrans_ioctl,
 228         .getgeo         = blktrans_getgeo,
 229 };
 230
 231 int add_mtd_blktrans_dev(struct mtd_blktrans_dev *new)
 232 {
 233         struct mtd_blktrans_ops *tr = new->tr;
 234         struct list_head *this;
 235         int last_devnum = -1;
 236         struct gendisk *gd;
 237
 238         if (!down_trylock(&mtd_table_mutex)) {
 239                 up(&mtd_table_mutex);
 240                 BUG();
 241         }
 242
 243         list_for_each(this, &tr->devs) {
 244                 struct mtd_blktrans_dev *d = list_entry(this, struct mtd_blktrans_dev, list);
 245                 if (new->devnum == -1) {
 246                         /* Use first free number */
 247                         if (d->devnum != last_devnum+1) {
 248                                 /* Found a free devnum. Plug it in here */
 249                                 new->devnum = last_devnum+1;
 250                                 list_add_tail(&new->list, &d->list);
 251                                 goto added;
 252                         }
 253                 } else if (d->devnum == new->devnum) {
 254                         /* Required number taken */
 255                         return -EBUSY;
 256                 } else if (d->devnum > new->devnum) {
 257                         /* Required number was free */
 258                         list_add_tail(&new->list, &d->list);
 259                         goto added;
 260                 }
 261                 last_devnum = d->devnum;
 262         }
 263         if (new->devnum == -1)
 264                 new->devnum = last_devnum+1;
 265
 266         if ((new->devnum << tr->part_bits) > 256) {
 267                 return -EBUSY;
 268         }
 269
 270         init_MUTEX(&new->sem);
 271         list_add_tail(&new->list, &tr->devs);
 272  added:
 273         if (!tr->writesect)
 274                 new->readonly = 1;
 275
 276         gd = alloc_disk(1 << tr->part_bits);
 277         if (!gd) {
 278                 list_del(&new->list);
 279                 return -ENOMEM;
 280         }
 281         gd->major = tr->major;
 282         gd->first_minor = (new->devnum) << tr->part_bits;
 283         gd->fops = &mtd_blktrans_ops;
 284
 285         if (tr->part_bits)
 286                 if (new->devnum < 26)
 287                         snprintf(gd->disk_name, sizeof(gd->disk_name),
 288                                  "%s%c", tr->name, 'a' + new->devnum);
 289                 else
 290                         snprintf(gd->disk_name, sizeof(gd->disk_name),
 291                                  "%s%c%c", tr->name,
 292                                  'a' - 1 + new->devnum / 26,
 293                                  'a' + new->devnum % 26);
 294         else
 295                 snprintf(gd->disk_name, sizeof(gd->disk_name),
 296                          "%s%d", tr->name, 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         INIT_LIST_HEAD(&tr->devs);
 415         list_add(&tr->list, &blktrans_majors);
 416
 417         for (i=0; i<MAX_MTD_DEVICES; i++) {
 418                 if (mtd_table[i] && mtd_table[i]->type != MTD_ABSENT)
 419                         tr->add_mtd(tr, mtd_table[i]);
 420         }
 421
 422         up(&mtd_table_mutex);
 423
 424         return 0;
 425 }
 426
 427 int deregister_mtd_blktrans(struct mtd_blktrans_ops *tr)
 428 {
 429         struct list_head *this, *next;
 430
 431         down(&mtd_table_mutex);
 432
 433         /* Clean up the kernel thread */
 434         tr->blkcore_priv->exiting = 1;
 435         wake_up(&tr->blkcore_priv->thread_wq);
 436         wait_for_completion(&tr->blkcore_priv->thread_dead);
 437
 438         /* Remove it from the list of active majors */
 439         list_del(&tr->list);
 440
 441         list_for_each_safe(this, next, &tr->devs) {
 442                 struct mtd_blktrans_dev *dev = list_entry(this, struct mtd_blktrans_dev, list);
 443                 tr->remove_dev(dev);
 444         }
 445
 446         blk_cleanup_queue(tr->blkcore_priv->rq);
 447         unregister_blkdev(tr->major, tr->name);
 448
 449         up(&mtd_table_mutex);
 450
 451         kfree(tr->blkcore_priv);
 452
 453         if (!list_empty(&tr->devs))
 454                 BUG();
 455         return 0;
 456 }
 457
 458 static void __exit mtd_blktrans_exit(void)
 459 {
 460         /* No race here -- if someone's currently in register_mtd_blktrans
 461            we're screwed anyway. */
 462         if (blktrans_notifier.list.next)
 463                 unregister_mtd_user(&blktrans_notifier);
 464 }
 465
 466 module_exit(mtd_blktrans_exit);
 467
 468 EXPORT_SYMBOL_GPL(register_mtd_blktrans);
 469 EXPORT_SYMBOL_GPL(deregister_mtd_blktrans);
 470 EXPORT_SYMBOL_GPL(add_mtd_blktrans_dev);
 471 EXPORT_SYMBOL_GPL(del_mtd_blktrans_dev);
 472
 473 MODULE_AUTHOR("David Woodhouse <dwmw2@infradead.org>");
 474 MODULE_LICENSE("GPL");
 475 MODULE_DESCRIPTION("Common interface to block layer for MTD 'translation layers'");