drivers/mtd/mtd_blkdevs.c

   1 /*
   2  * $Id: mtd_blkdevs.c,v 1.12 2003/05/21 01:00:59 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/blk.h>
  19 #include <linux/blkpg.h>
  20 #include <linux/spinlock.h>
  21 #include <linux/init.h>
  22 #include <asm/semaphore.h>
  23 #include <linux/devfs_fs_kernel.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;
  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         while (!tr->blkcore_priv->exiting) {
  97                 struct request *req;
  98                 struct mtd_blktrans_dev *dev;
  99                 int res = 0;
 100                 DECLARE_WAITQUEUE(wait, current);
 101
 102                 spin_lock_irq(rq->queue_lock);
 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                         continue;
 116                 }
 117
 118                 dev = req->rq_disk->private_data;
 119                 tr = dev->tr;
 120
 121                 spin_unlock_irq(rq->queue_lock);
 122
 123                 down(&dev->sem);
 124                 res = do_blktrans_request(tr, dev, req);
 125                 up(&dev->sem);
 126
 127                 spin_lock_irq(rq->queue_lock);
 128
 129                 end_request(req, res);
 130         }
 131         complete_and_exit(&tr->blkcore_priv->thread_dead, 0);
 132 }
 133
 134 static void mtd_blktrans_request(struct request_queue *rq)
 135 {
 136         struct mtd_blktrans_ops *tr = rq->queuedata;
 137         wake_up(&tr->blkcore_priv->thread_wq);
 138 }
 139
 140
 141 int blktrans_open(struct inode *i, struct file *f)
 142 {
 143         struct mtd_blktrans_dev *dev;
 144         struct mtd_blktrans_ops *tr;
 145         int ret = -ENODEV;
 146
 147         dev = i->i_bdev->bd_disk->private_data;
 148         tr = dev->tr;
 149
 150         if (!try_module_get(dev->mtd->owner))
 151                 goto out;
 152
 153         if (!try_module_get(tr->owner))
 154                 goto out_tr;
 155
 156         /* FIXME: Locking. A hot pluggable device can go away
 157            (del_mtd_device can be called for it) without its module
 158            being unloaded. */
 159         dev->mtd->usecount++;
 160
 161         ret = 0;
 162         if (tr->open && (ret = tr->open(dev, i, f))) {
 163                 dev->mtd->usecount--;
 164                 module_put(dev->mtd->owner);
 165         out_tr:
 166                 module_put(tr->owner);
 167         }
 168  out:
 169         return ret;
 170 }
 171
 172 int blktrans_release(struct inode *i, struct file *f)
 173 {
 174         struct mtd_blktrans_dev *dev;
 175         struct mtd_blktrans_ops *tr;
 176         int ret = 0;
 177
 178         dev = i->i_bdev->bd_disk->private_data;
 179         tr = dev->tr;
 180
 181         if (tr->release)
 182                 ret = tr->release(dev, i, f);
 183
 184         if (!ret) {
 185                 dev->mtd->usecount--;
 186                 module_put(dev->mtd->owner);
 187                 module_put(tr->owner);
 188         }
 189
 190         return ret;
 191 }
 192
 193
 194 static int blktrans_ioctl(struct inode *inode, struct file *file,
 195                               unsigned int cmd, unsigned long arg)
 196 {
 197         struct mtd_blktrans_dev *dev;
 198         struct mtd_blktrans_ops *tr;
 199         int ret = -ENOTTY;
 200
 201         dev = inode->i_bdev->bd_disk->private_data;
 202         tr = dev->tr;
 203
 204         if (tr->ioctl)
 205                 ret = tr->ioctl(dev, inode, file, cmd, arg);
 206
 207         if (ret == -ENOTTY && (cmd == BLKROSET || cmd == BLKFLSBUF)) {
 208                 /* The core code did the work, we had nothing to do. */
 209                 ret = 0;
 210         }
 211         return ret;
 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 };
 220
 221 int add_mtd_blktrans_dev(struct mtd_blktrans_dev *new)
 222 {
 223         struct mtd_blktrans_ops *tr = new->tr;
 224         struct list_head *this;
 225         int last_devnum = -1;
 226         struct gendisk *gd;
 227
 228         if (!down_trylock(&mtd_table_mutex)) {
 229                 up(&mtd_table_mutex);
 230                 BUG();
 231         }
 232
 233         list_for_each(this, &tr->devs) {
 234                 struct mtd_blktrans_dev *d = list_entry(this, struct mtd_blktrans_dev, list);
 235                 if (new->devnum == -1) {
 236                         /* Use first free number */
 237                         if (d->devnum != last_devnum+1) {
 238                                 /* Found a free devnum. Plug it in here */
 239                                 new->devnum = last_devnum+1;
 240                                 list_add_tail(&new->list, &d->list);
 241                                 goto added;
 242                         }
 243                 } else if (d->devnum == new->devnum) {
 244                         /* Required number taken */
 245                         return -EBUSY;
 246                 } else if (d->devnum > new->devnum) {
 247                         /* Required number was free */
 248                         list_add_tail(&new->list, &d->list);
 249                         goto added;
 250                 }
 251                 last_devnum = d->devnum;
 252         }
 253         if (new->devnum == -1)
 254                 new->devnum = last_devnum+1;
 255
 256         if ((new->devnum << tr->part_bits) > 256) {
 257                 return -EBUSY;
 258         }
 259
 260         init_MUTEX(&new->sem);
 261         list_add_tail(&new->list, &tr->devs);
 262  added:
 263         if (!tr->writesect)
 264                 new->readonly = 1;
 265
 266         gd = alloc_disk(1 << tr->part_bits);
 267         if (!gd) {
 268                 list_del(&new->list);
 269                 return -ENOMEM;
 270         }
 271         gd->major = tr->major;
 272         gd->first_minor = (new->devnum) << tr->part_bits;
 273         gd->fops = &mtd_blktrans_ops;
 274
 275         snprintf(gd->disk_name, sizeof(gd->disk_name),
 276                  "%s%c", tr->name, (tr->part_bits?'a':'0') + new->devnum);
 277         snprintf(gd->devfs_name, sizeof(gd->devfs_name),
 278                  "%s/%c", tr->name, (tr->part_bits?'a':'0') + new->devnum);
 279
 280         set_capacity(gd, new->size);
 281         gd->private_data = new;
 282         new->blkcore_priv = gd;
 283         gd->queue = &tr->blkcore_priv->rq;
 284
 285         if (new->readonly)
 286                 set_disk_ro(gd, 1);
 287
 288         add_disk(gd);
 289
 290         return 0;
 291 }
 292
 293 int del_mtd_blktrans_dev(struct mtd_blktrans_dev *old)
 294 {
 295         if (!down_trylock(&mtd_table_mutex)) {
 296                 up(&mtd_table_mutex);
 297                 BUG();
 298         }
 299
 300         list_del(&old->list);
 301
 302         del_gendisk(old->blkcore_priv);
 303         put_disk(old->blkcore_priv);
 304
 305         return 0;
 306 }
 307
 308 void blktrans_notify_remove(struct mtd_info *mtd)
 309 {
 310         struct list_head *this, *this2, *next;
 311
 312         list_for_each(this, &blktrans_majors) {
 313                 struct mtd_blktrans_ops *tr = list_entry(this, struct mtd_blktrans_ops, list);
 314
 315                 list_for_each_safe(this2, next, &tr->devs) {
 316                         struct mtd_blktrans_dev *dev = list_entry(this2, struct mtd_blktrans_dev, list);
 317
 318                         if (dev->mtd == mtd)
 319                                 tr->remove_dev(dev);
 320                 }
 321         }
 322 }
 323
 324 void blktrans_notify_add(struct mtd_info *mtd)
 325 {
 326         struct list_head *this;
 327
 328         if (mtd->type == MTD_ABSENT)
 329                 return;
 330
 331         printk("%s:%s %d: count %d\n", __FILE__, __func__, __LINE__, atomic_read(&mtd_table_mutex.count));
 332
 333         list_for_each(this, &blktrans_majors) {
 334                 struct mtd_blktrans_ops *tr = list_entry(this, struct mtd_blktrans_ops, list);
 335
 336                 tr->add_mtd(tr, mtd);
 337         }
 338
 339 }
 340
 341 static struct mtd_notifier blktrans_notifier = {
 342         .add = blktrans_notify_add,
 343         .remove = blktrans_notify_remove,
 344 };
 345
 346 int register_mtd_blktrans(struct mtd_blktrans_ops *tr)
 347 {
 348         int ret, i;
 349
 350         /* Register the notifier if/when the first device type is
 351            registered, to prevent the link/init ordering from fucking
 352            us over. */
 353         if (!blktrans_notifier.list.next)
 354                 register_mtd_user(&blktrans_notifier);
 355
 356         tr->blkcore_priv = kmalloc(sizeof(*tr->blkcore_priv), GFP_KERNEL);
 357         if (!tr->blkcore_priv)
 358                 return -ENOMEM;
 359
 360         memset(tr->blkcore_priv, 0, sizeof(*tr->blkcore_priv));
 361
 362         down(&mtd_table_mutex);
 363
 364         ret = register_blkdev(tr->major, tr->name);
 365         if (ret) {
 366                 printk(KERN_WARNING "Unable to register %s block device on major %d: %d\n",
 367                        tr->name, tr->major, ret);
 368                 kfree(tr->blkcore_priv);
 369                 up(&mtd_table_mutex);
 370                 return ret;
 371         }
 372         spin_lock_init(&tr->blkcore_priv->queue_lock);
 373         init_completion(&tr->blkcore_priv->thread_dead);
 374         init_waitqueue_head(&tr->blkcore_priv->thread_wq);
 375
 376         blk_init_queue(&tr->blkcore_priv->rq, mtd_blktrans_request,
 377                        &tr->blkcore_priv->queue_lock);
 378         tr->blkcore_priv->rq.queuedata = tr;
 379
 380         ret = kernel_thread(mtd_blktrans_thread, tr,
 381                             CLONE_FS|CLONE_FILES|CLONE_SIGHAND);
 382         if (ret < 0) {
 383                 blk_cleanup_queue(&tr->blkcore_priv->rq);
 384                 unregister_blkdev(tr->major, tr->name);
 385                 kfree(tr->blkcore_priv);
 386                 up(&mtd_table_mutex);
 387                 return ret;
 388         }
 389
 390         devfs_mk_dir(tr->name);
 391
 392         INIT_LIST_HEAD(&tr->devs);
 393         list_add(&tr->list, &blktrans_majors);
 394
 395         printk("%s:%s %d: count %d\n", __FILE__, __func__, __LINE__, atomic_read(&mtd_table_mutex.count));
 396
 397         for (i=0; i<MAX_MTD_DEVICES; i++) {
 398                 if (mtd_table[i] && mtd_table[i]->type != MTD_ABSENT)
 399                         tr->add_mtd(tr, mtd_table[i]);
 400         }
 401
 402         up(&mtd_table_mutex);
 403
 404         return 0;
 405 }
 406
 407 int deregister_mtd_blktrans(struct mtd_blktrans_ops *tr)
 408 {
 409         struct list_head *this, *next;
 410
 411         down(&mtd_table_mutex);
 412
 413         /* Clean up the kernel thread */
 414         tr->blkcore_priv->exiting = 1;
 415         wake_up(&tr->blkcore_priv->thread_wq);
 416         wait_for_completion(&tr->blkcore_priv->thread_dead);
 417
 418         /* Remove it from the list of active majors */
 419         list_del(&tr->list);
 420
 421         list_for_each_safe(this, next, &tr->devs) {
 422                 struct mtd_blktrans_dev *dev = list_entry(this, struct mtd_blktrans_dev, list);
 423                 tr->remove_dev(dev);
 424         }
 425
 426         devfs_remove(tr->name);
 427         blk_cleanup_queue(&tr->blkcore_priv->rq);
 428         unregister_blkdev(tr->major, tr->name);
 429
 430         up(&mtd_table_mutex);
 431
 432         kfree(tr->blkcore_priv);
 433
 434         if (!list_empty(&tr->devs))
 435                 BUG();
 436         return 0;
 437 }
 438
 439 static void __exit mtd_blktrans_exit(void)
 440 {
 441         /* No race here -- if someone's currently in register_mtd_blktrans
 442            we're screwed anyway. */
 443         if (blktrans_notifier.list.next)
 444                 unregister_mtd_user(&blktrans_notifier);
 445 }
 446
 447 module_exit(mtd_blktrans_exit);
 448
 449 EXPORT_SYMBOL_GPL(register_mtd_blktrans);
 450 EXPORT_SYMBOL_GPL(deregister_mtd_blktrans);
 451 EXPORT_SYMBOL_GPL(add_mtd_blktrans_dev);
 452 EXPORT_SYMBOL_GPL(del_mtd_blktrans_dev);
 453
 454 MODULE_AUTHOR("David Woodhouse <dwmw2@infradead.org>");
 455 MODULE_LICENSE("GPL");
 456 MODULE_DESCRIPTION("Common interface to block layer for MTD 'translation layers'");