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 #include "mtdcore.h"
  27
  28 static LIST_HEAD(blktrans_majors);
  29
  30 struct mtd_blkcore_priv {
  31         struct task_struct *thread;
  32         struct request_queue *rq;
  33         spinlock_t queue_lock;
  34 };
  35
  36 static int do_blktrans_request(struct mtd_blktrans_ops *tr,
  37                                struct mtd_blktrans_dev *dev,
  38                                struct request *req)
  39 {
  40         unsigned long block, nsect;
  41         char *buf;
  42
  43         block = req->sector << 9 >> tr->blkshift;
  44         nsect = req->current_nr_sectors << 9 >> tr->blkshift;
  45
  46         buf = req->buffer;
  47
  48         if (!blk_fs_request(req))
  49                 return 0;
  50
  51         if (req->sector + req->current_nr_sectors > get_capacity(req->rq_disk))
  52                 return 0;
  53
  54         switch(rq_data_dir(req)) {
  55         case READ:
  56                 for (; nsect > 0; nsect--, block++, buf += tr->blksize)
  57                         if (tr->readsect(dev, block, buf))
  58                                 return 0;
  59                 return 1;
  60
  61         case WRITE:
  62                 if (!tr->writesect)
  63                         return 0;
  64
  65                 for (; nsect > 0; nsect--, block++, buf += tr->blksize)
  66                         if (tr->writesect(dev, block, buf))
  67                                 return 0;
  68                 return 1;
  69
  70         default:
  71                 printk(KERN_NOTICE "Unknown request %u\n", rq_data_dir(req));
  72                 return 0;
  73         }
  74 }
  75
  76 static int mtd_blktrans_thread(void *arg)
  77 {
  78         struct mtd_blktrans_ops *tr = arg;
  79         struct request_queue *rq = tr->blkcore_priv->rq;
  80
  81         /* we might get involved when memory gets low, so use PF_MEMALLOC */
  82         current->flags |= PF_MEMALLOC | PF_NOFREEZE;
  83
  84         spin_lock_irq(rq->queue_lock);
  85         while (!kthread_should_stop()) {
  86                 struct request *req;
  87                 struct mtd_blktrans_dev *dev;
  88                 int res = 0;
  89
  90                 req = elv_next_request(rq);
  91
  92                 if (!req) {
  93                         set_current_state(TASK_INTERRUPTIBLE);
  94                         spin_unlock_irq(rq->queue_lock);
  95                         schedule();
  96                         spin_lock_irq(rq->queue_lock);
  97                         continue;
  98                 }
  99
 100                 dev = req->rq_disk->private_data;
 101                 tr = dev->tr;
 102
 103                 spin_unlock_irq(rq->queue_lock);
 104
 105                 mutex_lock(&dev->lock);
 106                 res = do_blktrans_request(tr, dev, req);
 107                 mutex_unlock(&dev->lock);
 108
 109                 spin_lock_irq(rq->queue_lock);
 110
 111                 end_request(req, res);
 112         }
 113         spin_unlock_irq(rq->queue_lock);
 114
 115         return 0;
 116 }
 117
 118 static void mtd_blktrans_request(struct request_queue *rq)
 119 {
 120         struct mtd_blktrans_ops *tr = rq->queuedata;
 121         wake_up_process(tr->blkcore_priv->thread);
 122 }
 123
 124
 125 static int blktrans_open(struct inode *i, struct file *f)
 126 {
 127         struct mtd_blktrans_dev *dev;
 128         struct mtd_blktrans_ops *tr;
 129         int ret = -ENODEV;
 130
 131         dev = i->i_bdev->bd_disk->private_data;
 132         tr = dev->tr;
 133
 134         if (!try_module_get(dev->mtd->owner))
 135                 goto out;
 136
 137         if (!try_module_get(tr->owner))
 138                 goto out_tr;
 139
 140         /* FIXME: Locking. A hot pluggable device can go away
 141            (del_mtd_device can be called for it) without its module
 142            being unloaded. */
 143         dev->mtd->usecount++;
 144
 145         ret = 0;
 146         if (tr->open && (ret = tr->open(dev))) {
 147                 dev->mtd->usecount--;
 148                 module_put(dev->mtd->owner);
 149         out_tr:
 150                 module_put(tr->owner);
 151         }
 152  out:
 153         return ret;
 154 }
 155
 156 static int blktrans_release(struct inode *i, struct file *f)
 157 {
 158         struct mtd_blktrans_dev *dev;
 159         struct mtd_blktrans_ops *tr;
 160         int ret = 0;
 161
 162         dev = i->i_bdev->bd_disk->private_data;
 163         tr = dev->tr;
 164
 165         if (tr->release)
 166                 ret = tr->release(dev);
 167
 168         if (!ret) {
 169                 dev->mtd->usecount--;
 170                 module_put(dev->mtd->owner);
 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 inode *inode, struct file *file,
 187                               unsigned int cmd, unsigned long arg)
 188 {
 189         struct mtd_blktrans_dev *dev = inode->i_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 struct block_device_operations mtd_blktrans_ops = {
 204         .owner          = THIS_MODULE,
 205         .open           = blktrans_open,
 206         .release        = blktrans_release,
 207         .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 list_head *this;
 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(this, &tr->devs) {
 224                 struct mtd_blktrans_dev *d = list_entry(this, struct mtd_blktrans_dev, 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         mutex_init(&new->lock);
 251         list_add_tail(&new->list, &tr->devs);
 252  added:
 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 list_head *this, *this2, *next;
 312
 313         list_for_each(this, &blktrans_majors) {
 314                 struct mtd_blktrans_ops *tr = list_entry(this, struct mtd_blktrans_ops, list);
 315
 316                 list_for_each_safe(this2, next, &tr->devs) {
 317                         struct mtd_blktrans_dev *dev = list_entry(this2, struct mtd_blktrans_dev, list);
 318
 319                         if (dev->mtd == mtd)
 320                                 tr->remove_dev(dev);
 321                 }
 322         }
 323 }
 324
 325 static void blktrans_notify_add(struct mtd_info *mtd)
 326 {
 327         struct list_head *this;
 328
 329         if (mtd->type == MTD_ABSENT)
 330                 return;
 331
 332         list_for_each(this, &blktrans_majors) {
 333                 struct mtd_blktrans_ops *tr = list_entry(this, struct mtd_blktrans_ops, list);
 334
 335                 tr->add_mtd(tr, mtd);
 336         }
 337
 338 }
 339
 340 static struct mtd_notifier blktrans_notifier = {
 341         .add = blktrans_notify_add,
 342         .remove = blktrans_notify_remove,
 343 };
 344
 345 int register_mtd_blktrans(struct mtd_blktrans_ops *tr)
 346 {
 347         int ret, i;
 348
 349         /* Register the notifier if/when the first device type is
 350            registered, to prevent the link/init ordering from fucking
 351            us over. */
 352         if (!blktrans_notifier.list.next)
 353                 register_mtd_user(&blktrans_notifier);
 354
 355         tr->blkcore_priv = kzalloc(sizeof(*tr->blkcore_priv), GFP_KERNEL);
 356         if (!tr->blkcore_priv)
 357                 return -ENOMEM;
 358
 359         mutex_lock(&mtd_table_mutex);
 360
 361         ret = register_blkdev(tr->major, tr->name);
 362         if (ret) {
 363                 printk(KERN_WARNING "Unable to register %s block device on major %d: %d\n",
 364                        tr->name, tr->major, ret);
 365                 kfree(tr->blkcore_priv);
 366                 mutex_unlock(&mtd_table_mutex);
 367                 return ret;
 368         }
 369         spin_lock_init(&tr->blkcore_priv->queue_lock);
 370
 371         tr->blkcore_priv->rq = blk_init_queue(mtd_blktrans_request, &tr->blkcore_priv->queue_lock);
 372         if (!tr->blkcore_priv->rq) {
 373                 unregister_blkdev(tr->major, tr->name);
 374                 kfree(tr->blkcore_priv);
 375                 mutex_unlock(&mtd_table_mutex);
 376                 return -ENOMEM;
 377         }
 378
 379         tr->blkcore_priv->rq->queuedata = tr;
 380         blk_queue_hardsect_size(tr->blkcore_priv->rq, tr->blksize);
 381         tr->blkshift = ffs(tr->blksize) - 1;
 382
 383         tr->blkcore_priv->thread = kthread_run(mtd_blktrans_thread, tr,
 384                         "%sd", tr->name);
 385         if (IS_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 PTR_ERR(tr->blkcore_priv->thread);
 391         }
 392
 393         INIT_LIST_HEAD(&tr->devs);
 394         list_add(&tr->list, &blktrans_majors);
 395
 396         for (i=0; i<MAX_MTD_DEVICES; i++) {
 397                 if (mtd_table[i] && mtd_table[i]->type != MTD_ABSENT)
 398                         tr->add_mtd(tr, mtd_table[i]);
 399         }
 400
 401         mutex_unlock(&mtd_table_mutex);
 402
 403         return 0;
 404 }
 405
 406 int deregister_mtd_blktrans(struct mtd_blktrans_ops *tr)
 407 {
 408         struct list_head *this, *next;
 409
 410         mutex_lock(&mtd_table_mutex);
 411
 412         /* Clean up the kernel thread */
 413         kthread_stop(tr->blkcore_priv->thread);
 414
 415         /* Remove it from the list of active majors */
 416         list_del(&tr->list);
 417
 418         list_for_each_safe(this, next, &tr->devs) {
 419                 struct mtd_blktrans_dev *dev = list_entry(this, struct mtd_blktrans_dev, list);
 420                 tr->remove_dev(dev);
 421         }
 422
 423         blk_cleanup_queue(tr->blkcore_priv->rq);
 424         unregister_blkdev(tr->major, tr->name);
 425
 426         mutex_unlock(&mtd_table_mutex);
 427
 428         kfree(tr->blkcore_priv);
 429
 430         BUG_ON(!list_empty(&tr->devs));
 431         return 0;
 432 }
 433
 434 static void __exit mtd_blktrans_exit(void)
 435 {
 436         /* No race here -- if someone's currently in register_mtd_blktrans
 437            we're screwed anyway. */
 438         if (blktrans_notifier.list.next)
 439                 unregister_mtd_user(&blktrans_notifier);
 440 }
 441
 442 module_exit(mtd_blktrans_exit);
 443
 444 EXPORT_SYMBOL_GPL(register_mtd_blktrans);
 445 EXPORT_SYMBOL_GPL(deregister_mtd_blktrans);
 446 EXPORT_SYMBOL_GPL(add_mtd_blktrans_dev);
 447 EXPORT_SYMBOL_GPL(del_mtd_blktrans_dev);
 448
 449 MODULE_AUTHOR("David Woodhouse <dwmw2@infradead.org>");
 450 MODULE_LICENSE("GPL");
 451 MODULE_DESCRIPTION("Common interface to block layer for MTD 'translation layers'");