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 <linux/kthread.h>
  24 #include <asm/uaccess.h>
  25
  26 static LIST_HEAD(blktrans_majors);
  27
  28 extern struct mutex 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 << 9 >> tr->blkshift;
  47         nsect = req->current_nr_sectors << 9 >> tr->blkshift;
  48
  49         buf = req->buffer;
  50
  51         if (!blk_fs_request(req))
  52                 return 0;
  53
  54         if (req->sector + req->current_nr_sectors > get_capacity(req->rq_disk))
  55                 return 0;
  56
  57         switch(rq_data_dir(req)) {
  58         case READ:
  59                 for (; nsect > 0; nsect--, block++, buf += tr->blksize)
  60                         if (tr->readsect(dev, block, buf))
  61                                 return 0;
  62                 return 1;
  63
  64         case WRITE:
  65                 if (!tr->writesect)
  66                         return 0;
  67
  68                 for (; nsect > 0; nsect--, block++, buf += tr->blksize)
  69                         if (tr->writesect(dev, block, buf))
  70                                 return 0;
  71                 return 1;
  72
  73         default:
  74                 printk(KERN_NOTICE "Unknown request %u\n", rq_data_dir(req));
  75                 return 0;
  76         }
  77 }
  78
  79 static int mtd_blktrans_thread(void *arg)
  80 {
  81         struct mtd_blktrans_ops *tr = arg;
  82         struct request_queue *rq = tr->blkcore_priv->rq;
  83
  84         /* we might get involved when memory gets low, so use PF_MEMALLOC */
  85         current->flags |= PF_MEMALLOC | PF_NOFREEZE;
  86
  87         spin_lock_irq(rq->queue_lock);
  88
  89         while (!tr->blkcore_priv->exiting) {
  90                 struct request *req;
  91                 struct mtd_blktrans_dev *dev;
  92                 int res = 0;
  93                 DECLARE_WAITQUEUE(wait, current);
  94
  95                 req = elv_next_request(rq);
  96
  97                 if (!req) {
  98                         add_wait_queue(&tr->blkcore_priv->thread_wq, &wait);
  99                         set_current_state(TASK_INTERRUPTIBLE);
 100
 101                         spin_unlock_irq(rq->queue_lock);
 102
 103                         schedule();
 104                         remove_wait_queue(&tr->blkcore_priv->thread_wq, &wait);
 105
 106                         spin_lock_irq(rq->queue_lock);
 107
 108                         continue;
 109                 }
 110
 111                 dev = req->rq_disk->private_data;
 112                 tr = dev->tr;
 113
 114                 spin_unlock_irq(rq->queue_lock);
 115
 116                 mutex_lock(&dev->lock);
 117                 res = do_blktrans_request(tr, dev, req);
 118                 mutex_unlock(&dev->lock);
 119
 120                 spin_lock_irq(rq->queue_lock);
 121
 122                 end_request(req, res);
 123         }
 124         spin_unlock_irq(rq->queue_lock);
 125
 126         complete_and_exit(&tr->blkcore_priv->thread_dead, 0);
 127 }
 128
 129 static void mtd_blktrans_request(struct request_queue *rq)
 130 {
 131         struct mtd_blktrans_ops *tr = rq->queuedata;
 132         wake_up(&tr->blkcore_priv->thread_wq);
 133 }
 134
 135
 136 static int blktrans_open(struct inode *i, struct file *f)
 137 {
 138         struct mtd_blktrans_dev *dev;
 139         struct mtd_blktrans_ops *tr;
 140         int ret = -ENODEV;
 141
 142         dev = i->i_bdev->bd_disk->private_data;
 143         tr = dev->tr;
 144
 145         if (!try_module_get(dev->mtd->owner))
 146                 goto out;
 147
 148         if (!try_module_get(tr->owner))
 149                 goto out_tr;
 150
 151         /* FIXME: Locking. A hot pluggable device can go away
 152            (del_mtd_device can be called for it) without its module
 153            being unloaded. */
 154         dev->mtd->usecount++;
 155
 156         ret = 0;
 157         if (tr->open && (ret = tr->open(dev))) {
 158                 dev->mtd->usecount--;
 159                 module_put(dev->mtd->owner);
 160         out_tr:
 161                 module_put(tr->owner);
 162         }
 163  out:
 164         return ret;
 165 }
 166
 167 static int blktrans_release(struct inode *i, struct file *f)
 168 {
 169         struct mtd_blktrans_dev *dev;
 170         struct mtd_blktrans_ops *tr;
 171         int ret = 0;
 172
 173         dev = i->i_bdev->bd_disk->private_data;
 174         tr = dev->tr;
 175
 176         if (tr->release)
 177                 ret = tr->release(dev);
 178
 179         if (!ret) {
 180                 dev->mtd->usecount--;
 181                 module_put(dev->mtd->owner);
 182                 module_put(tr->owner);
 183         }
 184
 185         return ret;
 186 }
 187
 188 static int blktrans_getgeo(struct block_device *bdev, struct hd_geometry *geo)
 189 {
 190         struct mtd_blktrans_dev *dev = bdev->bd_disk->private_data;
 191
 192         if (dev->tr->getgeo)
 193                 return dev->tr->getgeo(dev, geo);
 194         return -ENOTTY;
 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         default:
 210                 return -ENOTTY;
 211         }
 212 }
 213
 214 struct block_device_operations mtd_blktrans_ops = {
 215         .owner          = THIS_MODULE,
 216         .open           = blktrans_open,
 217         .release        = blktrans_release,
 218         .ioctl          = blktrans_ioctl,
 219         .getgeo         = blktrans_getgeo,
 220 };
 221
 222 int add_mtd_blktrans_dev(struct mtd_blktrans_dev *new)
 223 {
 224         struct mtd_blktrans_ops *tr = new->tr;
 225         struct list_head *this;
 226         int last_devnum = -1;
 227         struct gendisk *gd;
 228
 229         if (!!mutex_trylock(&mtd_table_mutex)) {
 230                 mutex_unlock(&mtd_table_mutex);
 231                 BUG();
 232         }
 233
 234         list_for_each(this, &tr->devs) {
 235                 struct mtd_blktrans_dev *d = list_entry(this, struct mtd_blktrans_dev, list);
 236                 if (new->devnum == -1) {
 237                         /* Use first free number */
 238                         if (d->devnum != last_devnum+1) {
 239                                 /* Found a free devnum. Plug it in here */
 240                                 new->devnum = last_devnum+1;
 241                                 list_add_tail(&new->list, &d->list);
 242                                 goto added;
 243                         }
 244                 } else if (d->devnum == new->devnum) {
 245                         /* Required number taken */
 246                         return -EBUSY;
 247                 } else if (d->devnum > new->devnum) {
 248                         /* Required number was free */
 249                         list_add_tail(&new->list, &d->list);
 250                         goto added;
 251                 }
 252                 last_devnum = d->devnum;
 253         }
 254         if (new->devnum == -1)
 255                 new->devnum = last_devnum+1;
 256
 257         if ((new->devnum << tr->part_bits) > 256) {
 258                 return -EBUSY;
 259         }
 260
 261         mutex_init(&new->lock);
 262         list_add_tail(&new->list, &tr->devs);
 263  added:
 264         if (!tr->writesect)
 265                 new->readonly = 1;
 266
 267         gd = alloc_disk(1 << tr->part_bits);
 268         if (!gd) {
 269                 list_del(&new->list);
 270                 return -ENOMEM;
 271         }
 272         gd->major = tr->major;
 273         gd->first_minor = (new->devnum) << tr->part_bits;
 274         gd->fops = &mtd_blktrans_ops;
 275
 276         if (tr->part_bits)
 277                 if (new->devnum < 26)
 278                         snprintf(gd->disk_name, sizeof(gd->disk_name),
 279                                  "%s%c", tr->name, 'a' + new->devnum);
 280                 else
 281                         snprintf(gd->disk_name, sizeof(gd->disk_name),
 282                                  "%s%c%c", tr->name,
 283                                  'a' - 1 + new->devnum / 26,
 284                                  'a' + new->devnum % 26);
 285         else
 286                 snprintf(gd->disk_name, sizeof(gd->disk_name),
 287                          "%s%d", tr->name, new->devnum);
 288
 289         /* 2.5 has capacity in units of 512 bytes while still
 290            having BLOCK_SIZE_BITS set to 10. Just to keep us amused. */
 291         set_capacity(gd, (new->size * tr->blksize) >> 9);
 292
 293         gd->private_data = new;
 294         new->blkcore_priv = gd;
 295         gd->queue = tr->blkcore_priv->rq;
 296
 297         if (new->readonly)
 298                 set_disk_ro(gd, 1);
 299
 300         add_disk(gd);
 301
 302         return 0;
 303 }
 304
 305 int del_mtd_blktrans_dev(struct mtd_blktrans_dev *old)
 306 {
 307         if (!!mutex_trylock(&mtd_table_mutex)) {
 308                 mutex_unlock(&mtd_table_mutex);
 309                 BUG();
 310         }
 311
 312         list_del(&old->list);
 313
 314         del_gendisk(old->blkcore_priv);
 315         put_disk(old->blkcore_priv);
 316
 317         return 0;
 318 }
 319
 320 static void blktrans_notify_remove(struct mtd_info *mtd)
 321 {
 322         struct list_head *this, *this2, *next;
 323
 324         list_for_each(this, &blktrans_majors) {
 325                 struct mtd_blktrans_ops *tr = list_entry(this, struct mtd_blktrans_ops, list);
 326
 327                 list_for_each_safe(this2, next, &tr->devs) {
 328                         struct mtd_blktrans_dev *dev = list_entry(this2, struct mtd_blktrans_dev, list);
 329
 330                         if (dev->mtd == mtd)
 331                                 tr->remove_dev(dev);
 332                 }
 333         }
 334 }
 335
 336 static void blktrans_notify_add(struct mtd_info *mtd)
 337 {
 338         struct list_head *this;
 339
 340         if (mtd->type == MTD_ABSENT)
 341                 return;
 342
 343         list_for_each(this, &blktrans_majors) {
 344                 struct mtd_blktrans_ops *tr = list_entry(this, struct mtd_blktrans_ops, list);
 345
 346                 tr->add_mtd(tr, mtd);
 347         }
 348
 349 }
 350
 351 static struct mtd_notifier blktrans_notifier = {
 352         .add = blktrans_notify_add,
 353         .remove = blktrans_notify_remove,
 354 };
 355
 356 int register_mtd_blktrans(struct mtd_blktrans_ops *tr)
 357 {
 358         struct task_struct *task;
 359         int ret, i;
 360
 361         /* Register the notifier if/when the first device type is
 362            registered, to prevent the link/init ordering from fucking
 363            us over. */
 364         if (!blktrans_notifier.list.next)
 365                 register_mtd_user(&blktrans_notifier);
 366
 367         tr->blkcore_priv = kzalloc(sizeof(*tr->blkcore_priv), GFP_KERNEL);
 368         if (!tr->blkcore_priv)
 369                 return -ENOMEM;
 370
 371         mutex_lock(&mtd_table_mutex);
 372
 373         ret = register_blkdev(tr->major, tr->name);
 374         if (ret) {
 375                 printk(KERN_WARNING "Unable to register %s block device on major %d: %d\n",
 376                        tr->name, tr->major, ret);
 377                 kfree(tr->blkcore_priv);
 378                 mutex_unlock(&mtd_table_mutex);
 379                 return ret;
 380         }
 381         spin_lock_init(&tr->blkcore_priv->queue_lock);
 382         init_completion(&tr->blkcore_priv->thread_dead);
 383         init_waitqueue_head(&tr->blkcore_priv->thread_wq);
 384
 385         tr->blkcore_priv->rq = blk_init_queue(mtd_blktrans_request, &tr->blkcore_priv->queue_lock);
 386         if (!tr->blkcore_priv->rq) {
 387                 unregister_blkdev(tr->major, tr->name);
 388                 kfree(tr->blkcore_priv);
 389                 mutex_unlock(&mtd_table_mutex);
 390                 return -ENOMEM;
 391         }
 392
 393         tr->blkcore_priv->rq->queuedata = tr;
 394         blk_queue_hardsect_size(tr->blkcore_priv->rq, tr->blksize);
 395         tr->blkshift = ffs(tr->blksize) - 1;
 396
 397         task = kthread_run(mtd_blktrans_thread, tr, "%sd", tr->name);
 398         if (IS_ERR(task)) {
 399                 blk_cleanup_queue(tr->blkcore_priv->rq);
 400                 unregister_blkdev(tr->major, tr->name);
 401                 kfree(tr->blkcore_priv);
 402                 mutex_unlock(&mtd_table_mutex);
 403                 return PTR_ERR(task);
 404         }
 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         mutex_unlock(&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         mutex_lock(&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         blk_cleanup_queue(tr->blkcore_priv->rq);
 439         unregister_blkdev(tr->major, tr->name);
 440
 441         mutex_unlock(&mtd_table_mutex);
 442
 443         kfree(tr->blkcore_priv);
 444
 445         BUG_ON(!list_empty(&tr->devs));
 446         return 0;
 447 }
 448
 449 static void __exit mtd_blktrans_exit(void)
 450 {
 451         /* No race here -- if someone's currently in register_mtd_blktrans
 452            we're screwed anyway. */
 453         if (blktrans_notifier.list.next)
 454                 unregister_mtd_user(&blktrans_notifier);
 455 }
 456
 457 module_exit(mtd_blktrans_exit);
 458
 459 EXPORT_SYMBOL_GPL(register_mtd_blktrans);
 460 EXPORT_SYMBOL_GPL(deregister_mtd_blktrans);
 461 EXPORT_SYMBOL_GPL(add_mtd_blktrans_dev);
 462 EXPORT_SYMBOL_GPL(del_mtd_blktrans_dev);
 463
 464 MODULE_AUTHOR("David Woodhouse <dwmw2@infradead.org>");
 465 MODULE_LICENSE("GPL");
 466 MODULE_DESCRIPTION("Common interface to block layer for MTD 'translation layers'");