drivers/mtd/mtd_blkdevs.c

   1 /*
   2  * (C) 2003 David Woodhouse <dwmw2@infradead.org>
   3  *
   4  * Interface to Linux 2.5 block layer for MTD 'translation layers'.
   5  *
   6  */
   7
   8 #include <linux/kernel.h>
   9 #include <linux/slab.h>
  10 #include <linux/module.h>
  11 #include <linux/list.h>
  12 #include <linux/fs.h>
  13 #include <linux/mtd/blktrans.h>
  14 #include <linux/mtd/mtd.h>
  15 #include <linux/blkdev.h>
  16 #include <linux/blkpg.h>
  17 #include <linux/freezer.h>
  18 #include <linux/spinlock.h>
  19 #include <linux/hdreg.h>
  20 #include <linux/init.h>
  21 #include <linux/mutex.h>
  22 #include <linux/kthread.h>
  23 #include <asm/uaccess.h>
  24
  25 #include "mtdcore.h"
  26
  27 static LIST_HEAD(blktrans_majors);
  28
  29 struct mtd_blkcore_priv {
  30         struct task_struct *thread;
  31         struct request_queue *rq;
  32         spinlock_t queue_lock;
  33 };
  34
  35 static int do_blktrans_request(struct mtd_blktrans_ops *tr,
  36                                struct mtd_blktrans_dev *dev,
  37                                struct request *req)
  38 {
  39         unsigned long block, nsect;
  40         char *buf;
  41
  42         block = blk_rq_pos(req) << 9 >> tr->blkshift;
  43         nsect = blk_rq_cur_bytes(req) >> tr->blkshift;
  44
  45         buf = req->buffer;
  46
  47         if (!blk_fs_request(req))
  48                 return -EIO;
  49
  50         if (blk_rq_pos(req) + blk_rq_cur_sectors(req) >
  51             get_capacity(req->rq_disk))
  52                 return -EIO;
  53
  54         if (blk_discard_rq(req))
  55                 return tr->discard(dev, block, nsect);
  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 -EIO;
  62                 rq_flush_dcache_pages(req);
  63                 return 0;
  64
  65         case WRITE:
  66                 if (!tr->writesect)
  67                         return -EIO;
  68
  69                 rq_flush_dcache_pages(req);
  70                 for (; nsect > 0; nsect--, block++, buf += tr->blksize)
  71                         if (tr->writesect(dev, block, buf))
  72                                 return -EIO;
  73                 return 0;
  74
  75         default:
  76                 printk(KERN_NOTICE "Unknown request %u\n", rq_data_dir(req));
  77                 return -EIO;
  78         }
  79 }
  80
  81 static int mtd_blktrans_thread(void *arg)
  82 {
  83         struct mtd_blktrans_ops *tr = arg;
  84         struct request_queue *rq = tr->blkcore_priv->rq;
  85         struct request *req = NULL;
  86
  87         spin_lock_irq(rq->queue_lock);
  88
  89         while (!kthread_should_stop()) {
  90                 struct mtd_blktrans_dev *dev;
  91                 int res;
  92
  93                 if (!req && !(req = blk_fetch_request(rq))) {
  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                 if (!__blk_end_request_cur(req, res))
 113                         req = NULL;
 114         }
 115
 116         if (req)
 117                 __blk_end_request_all(req, -EIO);
 118
 119         spin_unlock_irq(rq->queue_lock);
 120
 121         return 0;
 122 }
 123
 124 static void mtd_blktrans_request(struct request_queue *rq)
 125 {
 126         struct mtd_blktrans_ops *tr = rq->queuedata;
 127         wake_up_process(tr->blkcore_priv->thread);
 128 }
 129
 130
 131 static int blktrans_open(struct block_device *bdev, fmode_t mode)
 132 {
 133         struct mtd_blktrans_dev *dev = bdev->bd_disk->private_data;
 134         struct mtd_blktrans_ops *tr = dev->tr;
 135         int ret = -ENODEV;
 136
 137         if (!get_mtd_device(NULL, dev->mtd->index))
 138                 goto out;
 139
 140         if (!try_module_get(tr->owner))
 141                 goto out_tr;
 142
 143         /* FIXME: Locking. A hot pluggable device can go away
 144            (del_mtd_device can be called for it) without its module
 145            being unloaded. */
 146         dev->mtd->usecount++;
 147
 148         ret = 0;
 149         if (tr->open && (ret = tr->open(dev))) {
 150                 dev->mtd->usecount--;
 151                 put_mtd_device(dev->mtd);
 152         out_tr:
 153                 module_put(tr->owner);
 154         }
 155  out:
 156         return ret;
 157 }
 158
 159 static int blktrans_release(struct gendisk *disk, fmode_t mode)
 160 {
 161         struct mtd_blktrans_dev *dev = disk->private_data;
 162         struct mtd_blktrans_ops *tr = dev->tr;
 163         int ret = 0;
 164
 165         if (tr->release)
 166                 ret = tr->release(dev);
 167
 168         if (!ret) {
 169                 dev->mtd->usecount--;
 170                 put_mtd_device(dev->mtd);
 171                 module_put(tr->owner);
 172         }
 173
 174         return ret;
 175 }
 176
 177 static int blktrans_getgeo(struct block_device *bdev, struct hd_geometry *geo)
 178 {
 179         struct mtd_blktrans_dev *dev = bdev->bd_disk->private_data;
 180
 181         if (dev->tr->getgeo)
 182                 return dev->tr->getgeo(dev, geo);
 183         return -ENOTTY;
 184 }
 185
 186 static int blktrans_ioctl(struct block_device *bdev, fmode_t mode,
 187                               unsigned int cmd, unsigned long arg)
 188 {
 189         struct mtd_blktrans_dev *dev = bdev->bd_disk->private_data;
 190         struct mtd_blktrans_ops *tr = dev->tr;
 191
 192         switch (cmd) {
 193         case BLKFLSBUF:
 194                 if (tr->flush)
 195                         return tr->flush(dev);
 196                 /* The core code did the work, we had nothing to do. */
 197                 return 0;
 198         default:
 199                 return -ENOTTY;
 200         }
 201 }
 202
 203 static const struct block_device_operations mtd_blktrans_ops = {
 204         .owner          = THIS_MODULE,
 205         .open           = blktrans_open,
 206         .release        = blktrans_release,
 207         .locked_ioctl   = blktrans_ioctl,
 208         .getgeo         = blktrans_getgeo,
 209 };
 210
 211 int add_mtd_blktrans_dev(struct mtd_blktrans_dev *new)
 212 {
 213         struct mtd_blktrans_ops *tr = new->tr;
 214         struct mtd_blktrans_dev *d;
 215         int last_devnum = -1;
 216         struct gendisk *gd;
 217
 218         if (mutex_trylock(&mtd_table_mutex)) {
 219                 mutex_unlock(&mtd_table_mutex);
 220                 BUG();
 221         }
 222
 223         list_for_each_entry(d, &tr->devs, list) {
 224                 if (new->devnum == -1) {
 225                         /* Use first free number */
 226                         if (d->devnum != last_devnum+1) {
 227                                 /* Found a free devnum. Plug it in here */
 228                                 new->devnum = last_devnum+1;
 229                                 list_add_tail(&new->list, &d->list);
 230                                 goto added;
 231                         }
 232                 } else if (d->devnum == new->devnum) {
 233                         /* Required number taken */
 234                         return -EBUSY;
 235                 } else if (d->devnum > new->devnum) {
 236                         /* Required number was free */
 237                         list_add_tail(&new->list, &d->list);
 238                         goto added;
 239                 }
 240                 last_devnum = d->devnum;
 241         }
 242         if (new->devnum == -1)
 243                 new->devnum = last_devnum+1;
 244
 245         /* Check that the device and any partitions will get valid
 246          * minor numbers and that the disk naming code below can cope
 247          * with this number. */
 248         if (new->devnum > (MINORMASK >> tr->part_bits) ||
 249             (tr->part_bits && new->devnum >= 27 * 26))
 250                 return -EBUSY;
 251
 252         list_add_tail(&new->list, &tr->devs);
 253  added:
 254         mutex_init(&new->lock);
 255         if (!tr->writesect)
 256                 new->readonly = 1;
 257
 258         gd = alloc_disk(1 << tr->part_bits);
 259         if (!gd) {
 260                 list_del(&new->list);
 261                 return -ENOMEM;
 262         }
 263         gd->major = tr->major;
 264         gd->first_minor = (new->devnum) << tr->part_bits;
 265         gd->fops = &mtd_blktrans_ops;
 266
 267         if (tr->part_bits)
 268                 if (new->devnum < 26)
 269                         snprintf(gd->disk_name, sizeof(gd->disk_name),
 270                                  "%s%c", tr->name, 'a' + new->devnum);
 271                 else
 272                         snprintf(gd->disk_name, sizeof(gd->disk_name),
 273                                  "%s%c%c", tr->name,
 274                                  'a' - 1 + new->devnum / 26,
 275                                  'a' + new->devnum % 26);
 276         else
 277                 snprintf(gd->disk_name, sizeof(gd->disk_name),
 278                          "%s%d", tr->name, new->devnum);
 279
 280         /* 2.5 has capacity in units of 512 bytes while still
 281            having BLOCK_SIZE_BITS set to 10. Just to keep us amused. */
 282         set_capacity(gd, (new->size * tr->blksize) >> 9);
 283
 284         gd->private_data = new;
 285         new->blkcore_priv = gd;
 286         gd->queue = tr->blkcore_priv->rq;
 287         gd->driverfs_dev = &new->mtd->dev;
 288
 289         if (new->readonly)
 290                 set_disk_ro(gd, 1);
 291
 292         add_disk(gd);
 293
 294         return 0;
 295 }
 296
 297 int del_mtd_blktrans_dev(struct mtd_blktrans_dev *old)
 298 {
 299         if (mutex_trylock(&mtd_table_mutex)) {
 300                 mutex_unlock(&mtd_table_mutex);
 301                 BUG();
 302         }
 303
 304         list_del(&old->list);
 305
 306         del_gendisk(old->blkcore_priv);
 307         put_disk(old->blkcore_priv);
 308
 309         return 0;
 310 }
 311
 312 static void blktrans_notify_remove(struct mtd_info *mtd)
 313 {
 314         struct mtd_blktrans_ops *tr;
 315         struct mtd_blktrans_dev *dev, *next;
 316
 317         list_for_each_entry(tr, &blktrans_majors, list)
 318                 list_for_each_entry_safe(dev, next, &tr->devs, list)
 319                         if (dev->mtd == mtd)
 320                                 tr->remove_dev(dev);
 321 }
 322
 323 static void blktrans_notify_add(struct mtd_info *mtd)
 324 {
 325         struct mtd_blktrans_ops *tr;
 326
 327         if (mtd->type == MTD_ABSENT)
 328                 return;
 329
 330         list_for_each_entry(tr, &blktrans_majors, list)
 331                 tr->add_mtd(tr, mtd);
 332 }
 333
 334 static struct mtd_notifier blktrans_notifier = {
 335         .add = blktrans_notify_add,
 336         .remove = blktrans_notify_remove,
 337 };
 338
 339 int register_mtd_blktrans(struct mtd_blktrans_ops *tr)
 340 {
 341         struct mtd_info *mtd;
 342         int ret;
 343
 344         /* Register the notifier if/when the first device type is
 345            registered, to prevent the link/init ordering from fucking
 346            us over. */
 347         if (!blktrans_notifier.list.next)
 348                 register_mtd_user(&blktrans_notifier);
 349
 350         tr->blkcore_priv = kzalloc(sizeof(*tr->blkcore_priv), GFP_KERNEL);
 351         if (!tr->blkcore_priv)
 352                 return -ENOMEM;
 353
 354         mutex_lock(&mtd_table_mutex);
 355
 356         ret = register_blkdev(tr->major, tr->name);
 357         if (ret) {
 358                 printk(KERN_WARNING "Unable to register %s block device on major %d: %d\n",
 359                        tr->name, tr->major, ret);
 360                 kfree(tr->blkcore_priv);
 361                 mutex_unlock(&mtd_table_mutex);
 362                 return ret;
 363         }
 364         spin_lock_init(&tr->blkcore_priv->queue_lock);
 365
 366         tr->blkcore_priv->rq = blk_init_queue(mtd_blktrans_request, &tr->blkcore_priv->queue_lock);
 367         if (!tr->blkcore_priv->rq) {
 368                 unregister_blkdev(tr->major, tr->name);
 369                 kfree(tr->blkcore_priv);
 370                 mutex_unlock(&mtd_table_mutex);
 371                 return -ENOMEM;
 372         }
 373
 374         tr->blkcore_priv->rq->queuedata = tr;
 375         blk_queue_logical_block_size(tr->blkcore_priv->rq, tr->blksize);
 376         if (tr->discard)
 377                 queue_flag_set_unlocked(QUEUE_FLAG_DISCARD,
 378                                         tr->blkcore_priv->rq);
 379
 380         tr->blkshift = ffs(tr->blksize) - 1;
 381
 382         tr->blkcore_priv->thread = kthread_run(mtd_blktrans_thread, tr,
 383                         "%sd", tr->name);
 384         if (IS_ERR(tr->blkcore_priv->thread)) {
 385                 ret = PTR_ERR(tr->blkcore_priv->thread);
 386                 blk_cleanup_queue(tr->blkcore_priv->rq);
 387                 unregister_blkdev(tr->major, tr->name);
 388                 kfree(tr->blkcore_priv);
 389                 mutex_unlock(&mtd_table_mutex);
 390                 return ret;
 391         }
 392
 393         INIT_LIST_HEAD(&tr->devs);
 394         list_add(&tr->list, &blktrans_majors);
 395
 396         mtd_for_each_device(mtd)
 397                 if (mtd->type != MTD_ABSENT)
 398                         tr->add_mtd(tr, mtd);
 399
 400         mutex_unlock(&mtd_table_mutex);
 401
 402         return 0;
 403 }
 404
 405 int deregister_mtd_blktrans(struct mtd_blktrans_ops *tr)
 406 {
 407         struct mtd_blktrans_dev *dev, *next;
 408
 409         mutex_lock(&mtd_table_mutex);
 410
 411         /* Clean up the kernel thread */
 412         kthread_stop(tr->blkcore_priv->thread);
 413
 414         /* Remove it from the list of active majors */
 415         list_del(&tr->list);
 416
 417         list_for_each_entry_safe(dev, next, &tr->devs, list)
 418                 tr->remove_dev(dev);
 419
 420         blk_cleanup_queue(tr->blkcore_priv->rq);
 421         unregister_blkdev(tr->major, tr->name);
 422
 423         mutex_unlock(&mtd_table_mutex);
 424
 425         kfree(tr->blkcore_priv);
 426
 427         BUG_ON(!list_empty(&tr->devs));
 428         return 0;
 429 }
 430
 431 static void __exit mtd_blktrans_exit(void)
 432 {
 433         /* No race here -- if someone's currently in register_mtd_blktrans
 434            we're screwed anyway. */
 435         if (blktrans_notifier.list.next)
 436                 unregister_mtd_user(&blktrans_notifier);
 437 }
 438
 439 module_exit(mtd_blktrans_exit);
 440
 441 EXPORT_SYMBOL_GPL(register_mtd_blktrans);
 442 EXPORT_SYMBOL_GPL(deregister_mtd_blktrans);
 443 EXPORT_SYMBOL_GPL(add_mtd_blktrans_dev);
 444 EXPORT_SYMBOL_GPL(del_mtd_blktrans_dev);
 445
 446 MODULE_AUTHOR("David Woodhouse <dwmw2@infradead.org>");
 447 MODULE_LICENSE("GPL");
 448 MODULE_DESCRIPTION("Common interface to block layer for MTD 'translation layers'");