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 << 9 >> tr->blkshift;
  46         nsect = req->current_nr_sectors << 9 >> tr->blkshift;
  47
  48         buf = req->buffer;
  49
  50         if (!blk_fs_request(req))
  51                 return 0;
  52
  53         if (req->sector + req->current_nr_sectors > 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 += tr->blksize)
  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 += tr->blksize)
  68                         if (tr->writesect(dev, block, buf))
  69                                 return 0;
  70                 return 1;
  71
  72         default:
  73                 printk(KERN_NOTICE "Unknown request %u\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                 mutex_lock(&dev->lock);
 127                 res = do_blktrans_request(tr, dev, req);
 128                 mutex_unlock(&dev->lock);
 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 static int blktrans_getgeo(struct block_device *bdev, struct hd_geometry *geo)
 199 {
 200         struct mtd_blktrans_dev *dev = bdev->bd_disk->private_data;
 201
 202         if (dev->tr->getgeo)
 203                 return dev->tr->getgeo(dev, geo);
 204         return -ENOTTY;
 205 }
 206
 207 static int blktrans_ioctl(struct inode *inode, struct file *file,
 208                               unsigned int cmd, unsigned long arg)
 209 {
 210         struct mtd_blktrans_dev *dev = inode->i_bdev->bd_disk->private_data;
 211         struct mtd_blktrans_ops *tr = dev->tr;
 212
 213         switch (cmd) {
 214         case BLKFLSBUF:
 215                 if (tr->flush)
 216                         return tr->flush(dev);
 217                 /* The core code did the work, we had nothing to do. */
 218                 return 0;
 219         default:
 220                 return -ENOTTY;
 221         }
 222 }
 223
 224 struct block_device_operations mtd_blktrans_ops = {
 225         .owner          = THIS_MODULE,
 226         .open           = blktrans_open,
 227         .release        = blktrans_release,
 228         .ioctl          = blktrans_ioctl,
 229         .getgeo         = blktrans_getgeo,
 230 };
 231
 232 int add_mtd_blktrans_dev(struct mtd_blktrans_dev *new)
 233 {
 234         struct mtd_blktrans_ops *tr = new->tr;
 235         struct list_head *this;
 236         int last_devnum = -1;
 237         struct gendisk *gd;
 238
 239         if (!!mutex_trylock(&mtd_table_mutex)) {
 240                 mutex_unlock(&mtd_table_mutex);
 241                 BUG();
 242         }
 243
 244         list_for_each(this, &tr->devs) {
 245                 struct mtd_blktrans_dev *d = list_entry(this, struct mtd_blktrans_dev, list);
 246                 if (new->devnum == -1) {
 247                         /* Use first free number */
 248                         if (d->devnum != last_devnum+1) {
 249                                 /* Found a free devnum. Plug it in here */
 250                                 new->devnum = last_devnum+1;
 251                                 list_add_tail(&new->list, &d->list);
 252                                 goto added;
 253                         }
 254                 } else if (d->devnum == new->devnum) {
 255                         /* Required number taken */
 256                         return -EBUSY;
 257                 } else if (d->devnum > new->devnum) {
 258                         /* Required number was free */
 259                         list_add_tail(&new->list, &d->list);
 260                         goto added;
 261                 }
 262                 last_devnum = d->devnum;
 263         }
 264         if (new->devnum == -1)
 265                 new->devnum = last_devnum+1;
 266
 267         if ((new->devnum << tr->part_bits) > 256) {
 268                 return -EBUSY;
 269         }
 270
 271         mutex_init(&new->lock);
 272         list_add_tail(&new->list, &tr->devs);
 273  added:
 274         if (!tr->writesect)
 275                 new->readonly = 1;
 276
 277         gd = alloc_disk(1 << tr->part_bits);
 278         if (!gd) {
 279                 list_del(&new->list);
 280                 return -ENOMEM;
 281         }
 282         gd->major = tr->major;
 283         gd->first_minor = (new->devnum) << tr->part_bits;
 284         gd->fops = &mtd_blktrans_ops;
 285
 286         if (tr->part_bits)
 287                 if (new->devnum < 26)
 288                         snprintf(gd->disk_name, sizeof(gd->disk_name),
 289                                  "%s%c", tr->name, 'a' + new->devnum);
 290                 else
 291                         snprintf(gd->disk_name, sizeof(gd->disk_name),
 292                                  "%s%c%c", tr->name,
 293                                  'a' - 1 + new->devnum / 26,
 294                                  'a' + new->devnum % 26);
 295         else
 296                 snprintf(gd->disk_name, sizeof(gd->disk_name),
 297                          "%s%d", tr->name, new->devnum);
 298
 299         /* 2.5 has capacity in units of 512 bytes while still
 300            having BLOCK_SIZE_BITS set to 10. Just to keep us amused. */
 301         set_capacity(gd, (new->size * tr->blksize) >> 9);
 302
 303         gd->private_data = new;
 304         new->blkcore_priv = gd;
 305         gd->queue = tr->blkcore_priv->rq;
 306
 307         if (new->readonly)
 308                 set_disk_ro(gd, 1);
 309
 310         add_disk(gd);
 311
 312         return 0;
 313 }
 314
 315 int del_mtd_blktrans_dev(struct mtd_blktrans_dev *old)
 316 {
 317         if (!!mutex_trylock(&mtd_table_mutex)) {
 318                 mutex_unlock(&mtd_table_mutex);
 319                 BUG();
 320         }
 321
 322         list_del(&old->list);
 323
 324         del_gendisk(old->blkcore_priv);
 325         put_disk(old->blkcore_priv);
 326
 327         return 0;
 328 }
 329
 330 static void blktrans_notify_remove(struct mtd_info *mtd)
 331 {
 332         struct list_head *this, *this2, *next;
 333
 334         list_for_each(this, &blktrans_majors) {
 335                 struct mtd_blktrans_ops *tr = list_entry(this, struct mtd_blktrans_ops, list);
 336
 337                 list_for_each_safe(this2, next, &tr->devs) {
 338                         struct mtd_blktrans_dev *dev = list_entry(this2, struct mtd_blktrans_dev, list);
 339
 340                         if (dev->mtd == mtd)
 341                                 tr->remove_dev(dev);
 342                 }
 343         }
 344 }
 345
 346 static void blktrans_notify_add(struct mtd_info *mtd)
 347 {
 348         struct list_head *this;
 349
 350         if (mtd->type == MTD_ABSENT)
 351                 return;
 352
 353         list_for_each(this, &blktrans_majors) {
 354                 struct mtd_blktrans_ops *tr = list_entry(this, struct mtd_blktrans_ops, list);
 355
 356                 tr->add_mtd(tr, mtd);
 357         }
 358
 359 }
 360
 361 static struct mtd_notifier blktrans_notifier = {
 362         .add = blktrans_notify_add,
 363         .remove = blktrans_notify_remove,
 364 };
 365
 366 int register_mtd_blktrans(struct mtd_blktrans_ops *tr)
 367 {
 368         int ret, i;
 369
 370         /* Register the notifier if/when the first device type is
 371            registered, to prevent the link/init ordering from fucking
 372            us over. */
 373         if (!blktrans_notifier.list.next)
 374                 register_mtd_user(&blktrans_notifier);
 375
 376         tr->blkcore_priv = kzalloc(sizeof(*tr->blkcore_priv), GFP_KERNEL);
 377         if (!tr->blkcore_priv)
 378                 return -ENOMEM;
 379
 380         mutex_lock(&mtd_table_mutex);
 381
 382         ret = register_blkdev(tr->major, tr->name);
 383         if (ret) {
 384                 printk(KERN_WARNING "Unable to register %s block device on major %d: %d\n",
 385                        tr->name, tr->major, ret);
 386                 kfree(tr->blkcore_priv);
 387                 mutex_unlock(&mtd_table_mutex);
 388                 return ret;
 389         }
 390         spin_lock_init(&tr->blkcore_priv->queue_lock);
 391         init_completion(&tr->blkcore_priv->thread_dead);
 392         init_waitqueue_head(&tr->blkcore_priv->thread_wq);
 393
 394         tr->blkcore_priv->rq = blk_init_queue(mtd_blktrans_request, &tr->blkcore_priv->queue_lock);
 395         if (!tr->blkcore_priv->rq) {
 396                 unregister_blkdev(tr->major, tr->name);
 397                 kfree(tr->blkcore_priv);
 398                 mutex_unlock(&mtd_table_mutex);
 399                 return -ENOMEM;
 400         }
 401
 402         tr->blkcore_priv->rq->queuedata = tr;
 403         blk_queue_hardsect_size(tr->blkcore_priv->rq, tr->blksize);
 404         tr->blkshift = ffs(tr->blksize) - 1;
 405
 406         ret = kernel_thread(mtd_blktrans_thread, tr, CLONE_KERNEL);
 407         if (ret < 0) {
 408                 blk_cleanup_queue(tr->blkcore_priv->rq);
 409                 unregister_blkdev(tr->major, tr->name);
 410                 kfree(tr->blkcore_priv);
 411                 mutex_unlock(&mtd_table_mutex);
 412                 return ret;
 413         }
 414
 415         INIT_LIST_HEAD(&tr->devs);
 416         list_add(&tr->list, &blktrans_majors);
 417
 418         for (i=0; i<MAX_MTD_DEVICES; i++) {
 419                 if (mtd_table[i] && mtd_table[i]->type != MTD_ABSENT)
 420                         tr->add_mtd(tr, mtd_table[i]);
 421         }
 422
 423         mutex_unlock(&mtd_table_mutex);
 424
 425         return 0;
 426 }
 427
 428 int deregister_mtd_blktrans(struct mtd_blktrans_ops *tr)
 429 {
 430         struct list_head *this, *next;
 431
 432         mutex_lock(&mtd_table_mutex);
 433
 434         /* Clean up the kernel thread */
 435         tr->blkcore_priv->exiting = 1;
 436         wake_up(&tr->blkcore_priv->thread_wq);
 437         wait_for_completion(&tr->blkcore_priv->thread_dead);
 438
 439         /* Remove it from the list of active majors */
 440         list_del(&tr->list);
 441
 442         list_for_each_safe(this, next, &tr->devs) {
 443                 struct mtd_blktrans_dev *dev = list_entry(this, struct mtd_blktrans_dev, list);
 444                 tr->remove_dev(dev);
 445         }
 446
 447         blk_cleanup_queue(tr->blkcore_priv->rq);
 448         unregister_blkdev(tr->major, tr->name);
 449
 450         mutex_unlock(&mtd_table_mutex);
 451
 452         kfree(tr->blkcore_priv);
 453
 454         BUG_ON(!list_empty(&tr->devs));
 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'");