release/src-rt-6.x/linux/linux-2.6/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 task_struct *thread;
  33         struct request_queue *rq;
  34         spinlock_t queue_lock;
  35 };
  36
  37 static int do_blktrans_request(struct mtd_blktrans_ops *tr,
  38                                struct mtd_blktrans_dev *dev,
  39                                struct request *req)
  40 {
  41         unsigned long block, nsect;
  42         char *buf;
  43
  44         block = req->sector << 9 >> tr->blkshift;
  45         nsect = req->current_nr_sectors << 9 >> tr->blkshift;
  46
  47         buf = req->buffer;
  48
  49         if (!blk_fs_request(req))
  50                 return 0;
  51
  52         if (req->sector + req->current_nr_sectors > 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 += tr->blksize)
  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 += tr->blksize)
  67                         if (tr->writesect(dev, block, buf))
  68                                 return 0;
  69                 return 1;
  70
  71         default:
  72                 printk(KERN_NOTICE "Unknown request %u\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         spin_lock_irq(rq->queue_lock);
  86         while (!kthread_should_stop()) {
  87                 struct request *req;
  88                 struct mtd_blktrans_dev *dev;
  89                 int res = 0;
  90
  91                 req = elv_next_request(rq);
  92
  93                 if (!req) {
  94                         set_current_state(TASK_INTERRUPTIBLE);
  95                         spin_unlock_irq(rq->queue_lock);
  96                         schedule();
  97                         spin_lock_irq(rq->queue_lock);
  98                         continue;
  99                 }
 100
 101                 dev = req->rq_disk->private_data;
 102                 tr = dev->tr;
 103
 104                 spin_unlock_irq(rq->queue_lock);
 105
 106                 mutex_lock(&dev->lock);
 107                 res = do_blktrans_request(tr, dev, req);
 108                 mutex_unlock(&dev->lock);
 109
 110                 spin_lock_irq(rq->queue_lock);
 111
 112                 end_request(req, res);
 113         }
 114         spin_unlock_irq(rq->queue_lock);
 115
 116         return 0;
 117 }
 118
 119 static void mtd_blktrans_request(struct request_queue *rq)
 120 {
 121         struct mtd_blktrans_ops *tr = rq->queuedata;
 122         wake_up_process(tr->blkcore_priv->thread);
 123 }
 124
 125
 126 static int blktrans_open(struct inode *i, struct file *f)
 127 {
 128         struct mtd_blktrans_dev *dev;
 129         struct mtd_blktrans_ops *tr;
 130         int ret = -ENODEV;
 131
 132         dev = i->i_bdev->bd_disk->private_data;
 133         tr = dev->tr;
 134
 135         if (!try_module_get(dev->mtd->owner))
 136                 goto out;
 137
 138         if (!try_module_get(tr->owner))
 139                 goto out_tr;
 140
 141         /* FIXME: Locking. A hot pluggable device can go away
 142            (del_mtd_device can be called for it) without its module
 143            being unloaded. */
 144         dev->mtd->usecount++;
 145
 146         ret = 0;
 147         if (tr->open && (ret = tr->open(dev))) {
 148                 dev->mtd->usecount--;
 149                 module_put(dev->mtd->owner);
 150         out_tr:
 151                 module_put(tr->owner);
 152         }
 153  out:
 154         return ret;
 155 }
 156
 157 static int blktrans_release(struct inode *i, struct file *f)
 158 {
 159         struct mtd_blktrans_dev *dev;
 160         struct mtd_blktrans_ops *tr;
 161         int ret = 0;
 162
 163         dev = i->i_bdev->bd_disk->private_data;
 164         tr = dev->tr;
 165
 166         if (tr->release)
 167                 ret = tr->release(dev);
 168
 169         if (!ret) {
 170                 dev->mtd->usecount--;
 171                 module_put(dev->mtd->owner);
 172                 module_put(tr->owner);
 173         }
 174
 175         return ret;
 176 }
 177
 178 static int blktrans_getgeo(struct block_device *bdev, struct hd_geometry *geo)
 179 {
 180         struct mtd_blktrans_dev *dev = bdev->bd_disk->private_data;
 181
 182         if (dev->tr->getgeo)
 183                 return dev->tr->getgeo(dev, geo);
 184         return -ENOTTY;
 185 }
 186
 187 static int blktrans_ioctl(struct inode *inode, struct file *file,
 188                               unsigned int cmd, unsigned long arg)
 189 {
 190         struct mtd_blktrans_dev *dev = inode->i_bdev->bd_disk->private_data;
 191         struct mtd_blktrans_ops *tr = dev->tr;
 192
 193         switch (cmd) {
 194         case BLKFLSBUF:
 195                 if (tr->flush)
 196                         return tr->flush(dev);
 197                 /* The core code did the work, we had nothing to do. */
 198                 return 0;
 199         default:
 200                 return -ENOTTY;
 201         }
 202 }
 203
 204 struct block_device_operations mtd_blktrans_ops = {
 205         .owner          = THIS_MODULE,
 206         .open           = blktrans_open,
 207         .release        = blktrans_release,
 208         .ioctl          = blktrans_ioctl,
 209         .getgeo         = blktrans_getgeo,
 210 };
 211
 212 int add_mtd_blktrans_dev(struct mtd_blktrans_dev *new)
 213 {
 214         struct mtd_blktrans_ops *tr = new->tr;
 215         struct mtd_blktrans_dev *d;
 216         int last_devnum = -1;
 217         struct gendisk *gd;
 218
 219         if (mutex_trylock(&mtd_table_mutex)) {
 220                 mutex_unlock(&mtd_table_mutex);
 221                 BUG();
 222         }
 223
 224         list_for_each_entry(d, &tr->devs, list) {
 225                 if (new->devnum == -1) {
 226                         /* Use first free number */
 227                         if (d->devnum != last_devnum+1) {
 228                                 /* Found a free devnum. Plug it in here */
 229                                 new->devnum = last_devnum+1;
 230                                 list_add_tail(&new->list, &d->list);
 231                                 goto added;
 232                         }
 233                 } else if (d->devnum == new->devnum) {
 234                         /* Required number taken */
 235                         return -EBUSY;
 236                 } else if (d->devnum > new->devnum) {
 237                         /* Required number was free */
 238                         list_add_tail(&new->list, &d->list);
 239                         goto added;
 240                 }
 241                 last_devnum = d->devnum;
 242         }
 243         if (new->devnum == -1)
 244                 new->devnum = last_devnum+1;
 245
 246         if ((new->devnum << tr->part_bits) > 256) {
 247                 return -EBUSY;
 248         }
 249
 250         list_add_tail(&new->list, &tr->devs);
 251  added:
 252         mutex_init(&new->lock);
 253         if (!tr->writesect)
 254                 new->readonly = 1;
 255
 256         gd = alloc_disk(1 << tr->part_bits);
 257         if (!gd) {
 258                 list_del(&new->list);
 259                 return -ENOMEM;
 260         }
 261         gd->major = tr->major;
 262         gd->first_minor = (new->devnum) << tr->part_bits;
 263         gd->fops = &mtd_blktrans_ops;
 264
 265         if (tr->part_bits)
 266                 if (new->devnum < 26)
 267                         snprintf(gd->disk_name, sizeof(gd->disk_name),
 268                                  "%s%c", tr->name, 'a' + new->devnum);
 269                 else
 270                         snprintf(gd->disk_name, sizeof(gd->disk_name),
 271                                  "%s%c%c", tr->name,
 272                                  'a' - 1 + new->devnum / 26,
 273                                  'a' + new->devnum % 26);
 274         else
 275                 snprintf(gd->disk_name, sizeof(gd->disk_name),
 276                          "%s%d", tr->name, new->devnum);
 277
 278         /* 2.5 has capacity in units of 512 bytes while still
 279            having BLOCK_SIZE_BITS set to 10. Just to keep us amused. */
 280         set_capacity(gd, (new->size * tr->blksize) >> 9);
 281
 282         gd->private_data = new;
 283         new->blkcore_priv = gd;
 284         gd->queue = tr->blkcore_priv->rq;
 285
 286         if (new->readonly)
 287                 set_disk_ro(gd, 1);
 288
 289         add_disk(gd);
 290
 291         return 0;
 292 }
 293
 294 int del_mtd_blktrans_dev(struct mtd_blktrans_dev *old)
 295 {
 296         if (mutex_trylock(&mtd_table_mutex)) {
 297                 mutex_unlock(&mtd_table_mutex);
 298                 BUG();
 299         }
 300
 301         list_del(&old->list);
 302
 303         del_gendisk(old->blkcore_priv);
 304         put_disk(old->blkcore_priv);
 305
 306         return 0;
 307 }
 308
 309 static void blktrans_notify_remove(struct mtd_info *mtd)
 310 {
 311         struct mtd_blktrans_ops *tr;
 312         struct mtd_blktrans_dev *dev, *next;
 313
 314         list_for_each_entry(tr, &blktrans_majors, list)
 315                 list_for_each_entry_safe(dev, next, &tr->devs, list)
 316                         if (dev->mtd == mtd)
 317                                 tr->remove_dev(dev);
 318 }
 319
 320 static void blktrans_notify_add(struct mtd_info *mtd)
 321 {
 322         struct mtd_blktrans_ops *tr;
 323
 324         if (mtd->type == MTD_ABSENT)
 325                 return;
 326
 327         list_for_each_entry(tr, &blktrans_majors, list)
 328                 tr->add_mtd(tr, mtd);
 329 }
 330
 331 static struct mtd_notifier blktrans_notifier = {
 332         .add = blktrans_notify_add,
 333         .remove = blktrans_notify_remove,
 334 };
 335
 336 int register_mtd_blktrans(struct mtd_blktrans_ops *tr)
 337 {
 338         int ret, i;
 339
 340         /* Register the notifier if/when the first device type is
 341            registered, to prevent the link/init ordering from fucking
 342            us over. */
 343         if (!blktrans_notifier.list.next)
 344                 register_mtd_user(&blktrans_notifier);
 345
 346         tr->blkcore_priv = kzalloc(sizeof(*tr->blkcore_priv), GFP_KERNEL);
 347         if (!tr->blkcore_priv)
 348                 return -ENOMEM;
 349
 350         mutex_lock(&mtd_table_mutex);
 351
 352         ret = register_blkdev(tr->major, tr->name);
 353         if (ret) {
 354                 printk(KERN_WARNING "Unable to register %s block device on major %d: %d\n",
 355                        tr->name, tr->major, ret);
 356                 kfree(tr->blkcore_priv);
 357                 mutex_unlock(&mtd_table_mutex);
 358                 return ret;
 359         }
 360         spin_lock_init(&tr->blkcore_priv->queue_lock);
 361
 362         tr->blkcore_priv->rq = blk_init_queue(mtd_blktrans_request, &tr->blkcore_priv->queue_lock);
 363         if (!tr->blkcore_priv->rq) {
 364                 unregister_blkdev(tr->major, tr->name);
 365                 kfree(tr->blkcore_priv);
 366                 mutex_unlock(&mtd_table_mutex);
 367                 return -ENOMEM;
 368         }
 369
 370         tr->blkcore_priv->rq->queuedata = tr;
 371         blk_queue_hardsect_size(tr->blkcore_priv->rq, tr->blksize);
 372         tr->blkshift = ffs(tr->blksize) - 1;
 373
 374         tr->blkcore_priv->thread = kthread_run(mtd_blktrans_thread, tr,
 375                         "%sd", tr->name);
 376         if (IS_ERR(tr->blkcore_priv->thread)) {
 377                 int ret = PTR_ERR(tr->blkcore_priv->thread);
 378                 blk_cleanup_queue(tr->blkcore_priv->rq);
 379                 unregister_blkdev(tr->major, tr->name);
 380                 kfree(tr->blkcore_priv);
 381                 mutex_unlock(&mtd_table_mutex);
 382                 return ret;
 383         }
 384
 385         INIT_LIST_HEAD(&tr->devs);
 386         list_add(&tr->list, &blktrans_majors);
 387
 388         for (i=0; i<MAX_MTD_DEVICES; i++) {
 389                 if (mtd_table[i] && mtd_table[i]->type != MTD_ABSENT)
 390                         tr->add_mtd(tr, mtd_table[i]);
 391         }
 392
 393         mutex_unlock(&mtd_table_mutex);
 394
 395         return 0;
 396 }
 397
 398 int deregister_mtd_blktrans(struct mtd_blktrans_ops *tr)
 399 {
 400         struct mtd_blktrans_dev *dev, *next;
 401
 402         mutex_lock(&mtd_table_mutex);
 403
 404         /* Clean up the kernel thread */
 405         kthread_stop(tr->blkcore_priv->thread);
 406
 407         /* Remove it from the list of active majors */
 408         list_del(&tr->list);
 409
 410         list_for_each_entry_safe(dev, next, &tr->devs, list)
 411                 tr->remove_dev(dev);
 412
 413         blk_cleanup_queue(tr->blkcore_priv->rq);
 414         unregister_blkdev(tr->major, tr->name);
 415
 416         mutex_unlock(&mtd_table_mutex);
 417
 418         kfree(tr->blkcore_priv);
 419
 420         BUG_ON(!list_empty(&tr->devs));
 421         return 0;
 422 }
 423
 424 static void __exit mtd_blktrans_exit(void)
 425 {
 426         /* No race here -- if someone's currently in register_mtd_blktrans
 427            we're screwed anyway. */
 428         if (blktrans_notifier.list.next)
 429                 unregister_mtd_user(&blktrans_notifier);
 430 }
 431
 432 module_exit(mtd_blktrans_exit);
 433
 434 EXPORT_SYMBOL_GPL(register_mtd_blktrans);
 435 EXPORT_SYMBOL_GPL(deregister_mtd_blktrans);
 436 EXPORT_SYMBOL_GPL(add_mtd_blktrans_dev);
 437 EXPORT_SYMBOL_GPL(del_mtd_blktrans_dev);
 438
 439 MODULE_AUTHOR("David Woodhouse <dwmw2@infradead.org>");
 440 MODULE_LICENSE("GPL");
 441 MODULE_DESCRIPTION("Common interface to block layer for MTD 'translation layers'");