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 blktrans_discard_request(struct request_queue *q,
  36                                     struct request *req)
  37 {
  38         req->cmd_type = REQ_TYPE_LINUX_BLOCK;
  39         req->cmd[0] = REQ_LB_OP_DISCARD;
  40         return 0;
  41 }
  42
  43 static int do_blktrans_request(struct mtd_blktrans_ops *tr,
  44                                struct mtd_blktrans_dev *dev,
  45                                struct request *req)
  46 {
  47         unsigned long block, nsect;
  48         char *buf;
  49
  50         block = blk_rq_pos(req) << 9 >> tr->blkshift;
  51         nsect = blk_rq_cur_bytes(req) >> tr->blkshift;
  52
  53         buf = req->buffer;
  54
  55         if (req->cmd_type == REQ_TYPE_LINUX_BLOCK &&
  56             req->cmd[0] == REQ_LB_OP_DISCARD)
  57                 return tr->discard(dev, block, nsect);
  58
  59         if (!blk_fs_request(req))
  60                 return -EIO;
  61
  62         if (blk_rq_pos(req) + blk_rq_cur_sectors(req) >
  63             get_capacity(req->rq_disk))
  64                 return -EIO;
  65
  66         switch(rq_data_dir(req)) {
  67         case READ:
  68                 for (; nsect > 0; nsect--, block++, buf += tr->blksize)
  69                         if (tr->readsect(dev, block, buf))
  70                                 return -EIO;
  71                 return 0;
  72
  73         case WRITE:
  74                 if (!tr->writesect)
  75                         return -EIO;
  76
  77                 for (; nsect > 0; nsect--, block++, buf += tr->blksize)
  78                         if (tr->writesect(dev, block, buf))
  79                                 return -EIO;
  80                 return 0;
  81
  82         default:
  83                 printk(KERN_NOTICE "Unknown request %u\n", rq_data_dir(req));
  84                 return -EIO;
  85         }
  86 }
  87
  88 static int mtd_blktrans_thread(void *arg)
  89 {
  90         struct mtd_blktrans_ops *tr = arg;
  91         struct request_queue *rq = tr->blkcore_priv->rq;
  92         struct request *req = NULL;
  93
  94         spin_lock_irq(rq->queue_lock);
  95
  96         while (!kthread_should_stop()) {
  97                 struct mtd_blktrans_dev *dev;
  98                 int res;
  99
 100                 if (!req && !(req = blk_fetch_request(rq))) {
 101                         set_current_state(TASK_INTERRUPTIBLE);
 102                         spin_unlock_irq(rq->queue_lock);
 103                         schedule();
 104                         spin_lock_irq(rq->queue_lock);
 105                         continue;
 106                 }
 107
 108                 dev = req->rq_disk->private_data;
 109                 tr = dev->tr;
 110
 111                 spin_unlock_irq(rq->queue_lock);
 112
 113                 mutex_lock(&dev->lock);
 114                 res = do_blktrans_request(tr, dev, req);
 115                 mutex_unlock(&dev->lock);
 116
 117                 spin_lock_irq(rq->queue_lock);
 118
 119                 if (!__blk_end_request_cur(req, res))
 120                         req = NULL;
 121         }
 122
 123         if (req)
 124                 __blk_end_request_all(req, -EIO);
 125
 126         spin_unlock_irq(rq->queue_lock);
 127
 128         return 0;
 129 }
 130
 131 static void mtd_blktrans_request(struct request_queue *rq)
 132 {
 133         struct mtd_blktrans_ops *tr = rq->queuedata;
 134         wake_up_process(tr->blkcore_priv->thread);
 135 }
 136
 137
 138 static int blktrans_open(struct block_device *bdev, fmode_t mode)
 139 {
 140         struct mtd_blktrans_dev *dev = bdev->bd_disk->private_data;
 141         struct mtd_blktrans_ops *tr = dev->tr;
 142         int ret = -ENODEV;
 143
 144         if (!get_mtd_device(NULL, dev->mtd->index))
 145                 goto out;
 146
 147         if (!try_module_get(tr->owner))
 148                 goto out_tr;
 149
 150         /* FIXME: Locking. A hot pluggable device can go away
 151            (del_mtd_device can be called for it) without its module
 152            being unloaded. */
 153         dev->mtd->usecount++;
 154
 155         ret = 0;
 156         if (tr->open && (ret = tr->open(dev))) {
 157                 dev->mtd->usecount--;
 158                 put_mtd_device(dev->mtd);
 159         out_tr:
 160                 module_put(tr->owner);
 161         }
 162  out:
 163         return ret;
 164 }
 165
 166 static int blktrans_release(struct gendisk *disk, fmode_t mode)
 167 {
 168         struct mtd_blktrans_dev *dev = disk->private_data;
 169         struct mtd_blktrans_ops *tr = dev->tr;
 170         int ret = 0;
 171
 172         if (tr->release)
 173                 ret = tr->release(dev);
 174
 175         if (!ret) {
 176                 dev->mtd->usecount--;
 177                 put_mtd_device(dev->mtd);
 178                 module_put(tr->owner);
 179         }
 180
 181         return ret;
 182 }
 183
 184 static int blktrans_getgeo(struct block_device *bdev, struct hd_geometry *geo)
 185 {
 186         struct mtd_blktrans_dev *dev = bdev->bd_disk->private_data;
 187
 188         if (dev->tr->getgeo)
 189                 return dev->tr->getgeo(dev, geo);
 190         return -ENOTTY;
 191 }
 192
 193 static int blktrans_ioctl(struct block_device *bdev, fmode_t mode,
 194                               unsigned int cmd, unsigned long arg)
 195 {
 196         struct mtd_blktrans_dev *dev = bdev->bd_disk->private_data;
 197         struct mtd_blktrans_ops *tr = dev->tr;
 198
 199         switch (cmd) {
 200         case BLKFLSBUF:
 201                 if (tr->flush)
 202                         return tr->flush(dev);
 203                 /* The core code did the work, we had nothing to do. */
 204                 return 0;
 205         default:
 206                 return -ENOTTY;
 207         }
 208 }
 209
 210 static const struct block_device_operations mtd_blktrans_ops = {
 211         .owner          = THIS_MODULE,
 212         .open           = blktrans_open,
 213         .release        = blktrans_release,
 214         .locked_ioctl   = blktrans_ioctl,
 215         .getgeo         = blktrans_getgeo,
 216 };
 217
 218 int add_mtd_blktrans_dev(struct mtd_blktrans_dev *new)
 219 {
 220         struct mtd_blktrans_ops *tr = new->tr;
 221         struct mtd_blktrans_dev *d;
 222         int last_devnum = -1;
 223         struct gendisk *gd;
 224
 225         if (mutex_trylock(&mtd_table_mutex)) {
 226                 mutex_unlock(&mtd_table_mutex);
 227                 BUG();
 228         }
 229
 230         list_for_each_entry(d, &tr->devs, list) {
 231                 if (new->devnum == -1) {
 232                         /* Use first free number */
 233                         if (d->devnum != last_devnum+1) {
 234                                 /* Found a free devnum. Plug it in here */
 235                                 new->devnum = last_devnum+1;
 236                                 list_add_tail(&new->list, &d->list);
 237                                 goto added;
 238                         }
 239                 } else if (d->devnum == new->devnum) {
 240                         /* Required number taken */
 241                         return -EBUSY;
 242                 } else if (d->devnum > new->devnum) {
 243                         /* Required number was free */
 244                         list_add_tail(&new->list, &d->list);
 245                         goto added;
 246                 }
 247                 last_devnum = d->devnum;
 248         }
 249         if (new->devnum == -1)
 250                 new->devnum = last_devnum+1;
 251
 252         if ((new->devnum << tr->part_bits) > 256) {
 253                 return -EBUSY;
 254         }
 255
 256         list_add_tail(&new->list, &tr->devs);
 257  added:
 258         mutex_init(&new->lock);
 259         if (!tr->writesect)
 260                 new->readonly = 1;
 261
 262         gd = alloc_disk(1 << tr->part_bits);
 263         if (!gd) {
 264                 list_del(&new->list);
 265                 return -ENOMEM;
 266         }
 267         gd->major = tr->major;
 268         gd->first_minor = (new->devnum) << tr->part_bits;
 269         gd->fops = &mtd_blktrans_ops;
 270
 271         if (tr->part_bits)
 272                 if (new->devnum < 26)
 273                         snprintf(gd->disk_name, sizeof(gd->disk_name),
 274                                  "%s%c", tr->name, 'a' + new->devnum);
 275                 else
 276                         snprintf(gd->disk_name, sizeof(gd->disk_name),
 277                                  "%s%c%c", tr->name,
 278                                  'a' - 1 + new->devnum / 26,
 279                                  'a' + new->devnum % 26);
 280         else
 281                 snprintf(gd->disk_name, sizeof(gd->disk_name),
 282                          "%s%d", tr->name, new->devnum);
 283
 284         /* 2.5 has capacity in units of 512 bytes while still
 285            having BLOCK_SIZE_BITS set to 10. Just to keep us amused. */
 286         set_capacity(gd, (new->size * tr->blksize) >> 9);
 287
 288         gd->private_data = new;
 289         new->blkcore_priv = gd;
 290         gd->queue = tr->blkcore_priv->rq;
 291         gd->driverfs_dev = &new->mtd->dev;
 292
 293         if (new->readonly)
 294                 set_disk_ro(gd, 1);
 295
 296         add_disk(gd);
 297
 298         return 0;
 299 }
 300
 301 int del_mtd_blktrans_dev(struct mtd_blktrans_dev *old)
 302 {
 303         if (mutex_trylock(&mtd_table_mutex)) {
 304                 mutex_unlock(&mtd_table_mutex);
 305                 BUG();
 306         }
 307
 308         list_del(&old->list);
 309
 310         del_gendisk(old->blkcore_priv);
 311         put_disk(old->blkcore_priv);
 312
 313         return 0;
 314 }
 315
 316 static void blktrans_notify_remove(struct mtd_info *mtd)
 317 {
 318         struct mtd_blktrans_ops *tr;
 319         struct mtd_blktrans_dev *dev, *next;
 320
 321         list_for_each_entry(tr, &blktrans_majors, list)
 322                 list_for_each_entry_safe(dev, next, &tr->devs, list)
 323                         if (dev->mtd == mtd)
 324                                 tr->remove_dev(dev);
 325 }
 326
 327 static void blktrans_notify_add(struct mtd_info *mtd)
 328 {
 329         struct mtd_blktrans_ops *tr;
 330
 331         if (mtd->type == MTD_ABSENT)
 332                 return;
 333
 334         list_for_each_entry(tr, &blktrans_majors, list)
 335                 tr->add_mtd(tr, mtd);
 336 }
 337
 338 static struct mtd_notifier blktrans_notifier = {
 339         .add = blktrans_notify_add,
 340         .remove = blktrans_notify_remove,
 341 };
 342
 343 int register_mtd_blktrans(struct mtd_blktrans_ops *tr)
 344 {
 345         int ret, i;
 346
 347         /* Register the notifier if/when the first device type is
 348            registered, to prevent the link/init ordering from fucking
 349            us over. */
 350         if (!blktrans_notifier.list.next)
 351                 register_mtd_user(&blktrans_notifier);
 352
 353         tr->blkcore_priv = kzalloc(sizeof(*tr->blkcore_priv), GFP_KERNEL);
 354         if (!tr->blkcore_priv)
 355                 return -ENOMEM;
 356
 357         mutex_lock(&mtd_table_mutex);
 358
 359         ret = register_blkdev(tr->major, tr->name);
 360         if (ret) {
 361                 printk(KERN_WARNING "Unable to register %s block device on major %d: %d\n",
 362                        tr->name, tr->major, ret);
 363                 kfree(tr->blkcore_priv);
 364                 mutex_unlock(&mtd_table_mutex);
 365                 return ret;
 366         }
 367         spin_lock_init(&tr->blkcore_priv->queue_lock);
 368
 369         tr->blkcore_priv->rq = blk_init_queue(mtd_blktrans_request, &tr->blkcore_priv->queue_lock);
 370         if (!tr->blkcore_priv->rq) {
 371                 unregister_blkdev(tr->major, tr->name);
 372                 kfree(tr->blkcore_priv);
 373                 mutex_unlock(&mtd_table_mutex);
 374                 return -ENOMEM;
 375         }
 376
 377         tr->blkcore_priv->rq->queuedata = tr;
 378         blk_queue_logical_block_size(tr->blkcore_priv->rq, tr->blksize);
 379         if (tr->discard)
 380                 blk_queue_set_discard(tr->blkcore_priv->rq,
 381                                       blktrans_discard_request);
 382
 383         tr->blkshift = ffs(tr->blksize) - 1;
 384
 385         tr->blkcore_priv->thread = kthread_run(mtd_blktrans_thread, tr,
 386                         "%sd", tr->name);
 387         if (IS_ERR(tr->blkcore_priv->thread)) {
 388                 ret = PTR_ERR(tr->blkcore_priv->thread);
 389                 blk_cleanup_queue(tr->blkcore_priv->rq);
 390                 unregister_blkdev(tr->major, tr->name);
 391                 kfree(tr->blkcore_priv);
 392                 mutex_unlock(&mtd_table_mutex);
 393                 return ret;
 394         }
 395
 396         INIT_LIST_HEAD(&tr->devs);
 397         list_add(&tr->list, &blktrans_majors);
 398
 399         for (i=0; i<MAX_MTD_DEVICES; i++) {
 400                 if (mtd_table[i] && mtd_table[i]->type != MTD_ABSENT)
 401                         tr->add_mtd(tr, mtd_table[i]);
 402         }
 403
 404         mutex_unlock(&mtd_table_mutex);
 405
 406         return 0;
 407 }
 408
 409 int deregister_mtd_blktrans(struct mtd_blktrans_ops *tr)
 410 {
 411         struct mtd_blktrans_dev *dev, *next;
 412
 413         mutex_lock(&mtd_table_mutex);
 414
 415         /* Clean up the kernel thread */
 416         kthread_stop(tr->blkcore_priv->thread);
 417
 418         /* Remove it from the list of active majors */
 419         list_del(&tr->list);
 420
 421         list_for_each_entry_safe(dev, next, &tr->devs, list)
 422                 tr->remove_dev(dev);
 423
 424         blk_cleanup_queue(tr->blkcore_priv->rq);
 425         unregister_blkdev(tr->major, tr->name);
 426
 427         mutex_unlock(&mtd_table_mutex);
 428
 429         kfree(tr->blkcore_priv);
 430
 431         BUG_ON(!list_empty(&tr->devs));
 432         return 0;
 433 }
 434
 435 static void __exit mtd_blktrans_exit(void)
 436 {
 437         /* No race here -- if someone's currently in register_mtd_blktrans
 438            we're screwed anyway. */
 439         if (blktrans_notifier.list.next)
 440                 unregister_mtd_user(&blktrans_notifier);
 441 }
 442
 443 module_exit(mtd_blktrans_exit);
 444
 445 EXPORT_SYMBOL_GPL(register_mtd_blktrans);
 446 EXPORT_SYMBOL_GPL(deregister_mtd_blktrans);
 447 EXPORT_SYMBOL_GPL(add_mtd_blktrans_dev);
 448 EXPORT_SYMBOL_GPL(del_mtd_blktrans_dev);
 449
 450 MODULE_AUTHOR("David Woodhouse <dwmw2@infradead.org>");
 451 MODULE_LICENSE("GPL");
 452 MODULE_DESCRIPTION("Common interface to block layer for MTD 'translation layers'");