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   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/freezer.h>
  20 #include <linux/spinlock.h>
  21 #include <linux/hdreg.h>
  22 #include <linux/init.h>
  23 #include <linux/mutex.h>
  24 #include <linux/kthread.h>
  25 #include <asm/uaccess.h>
  26
  27 static LIST_HEAD(blktrans_majors);
  28
  29 extern struct mutex mtd_table_mutex;
  30 extern struct mtd_info *mtd_table[];
  31
  32 struct mtd_blkcore_priv {
  33         struct task_struct *thread;
  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 << 9 >> tr->blkshift;
  46         nsect = req->current_nr_sectors << 9 >> tr->blkshift;
  47
  48         buf = req->buffer;
  49
  50         if (!blk_fs_request(req))
  51                 return 0;
  52
  53         if (req->sector + req->current_nr_sectors > get_capacity(req->rq_disk))
  54                 return 0;
  55
  56         switch(rq_data_dir(req)) {
  57         case READ:
  58                 for (; nsect > 0; nsect--, block++, buf += tr->blksize)
  59                         if (tr->readsect(dev, block, buf))
  60                                 return 0;
  61                 return 1;
  62
  63         case WRITE:
  64                 if (!tr->writesect)
  65                         return 0;
  66
  67                 for (; nsect > 0; nsect--, block++, buf += tr->blksize)
  68                         if (tr->writesect(dev, block, buf))
  69                                 return 0;
  70                 return 1;
  71
  72         default:
  73                 printk(KERN_NOTICE "Unknown request %u\n", rq_data_dir(req));
  74                 return 0;
  75         }
  76 }
  77
  78 static int mtd_blktrans_thread(void *arg)
  79 {
  80         struct mtd_blktrans_ops *tr = arg;
  81         struct request_queue *rq = tr->blkcore_priv->rq;
  82
  83         /* we might get involved when memory gets low, so use PF_MEMALLOC */
  84         current->flags |= PF_MEMALLOC;
  85
  86         spin_lock_irq(rq->queue_lock);
  87         while (!kthread_should_stop()) {
  88                 struct request *req;
  89                 struct mtd_blktrans_dev *dev;
  90                 int res = 0;
  91
  92                 req = elv_next_request(rq);
  93
  94                 if (!req) {
  95                         set_current_state(TASK_INTERRUPTIBLE);
  96                         spin_unlock_irq(rq->queue_lock);
  97                         schedule();
  98                         spin_lock_irq(rq->queue_lock);
  99                         continue;
 100                 }
 101
 102                 dev = req->rq_disk->private_data;
 103                 tr = dev->tr;
 104
 105                 spin_unlock_irq(rq->queue_lock);
 106
 107                 mutex_lock(&dev->lock);
 108                 res = do_blktrans_request(tr, dev, req);
 109                 mutex_unlock(&dev->lock);
 110
 111                 spin_lock_irq(rq->queue_lock);
 112
 113                 end_request(req, res);
 114         }
 115         spin_unlock_irq(rq->queue_lock);
 116
 117         return 0;
 118 }
 119
 120 static void mtd_blktrans_request(struct request_queue *rq)
 121 {
 122         struct mtd_blktrans_ops *tr = rq->queuedata;
 123         wake_up_process(tr->blkcore_priv->thread);
 124 }
 125
 126
 127 static int blktrans_open(struct inode *i, struct file *f)
 128 {
 129         struct mtd_blktrans_dev *dev;
 130         struct mtd_blktrans_ops *tr;
 131         int ret = -ENODEV;
 132
 133         dev = i->i_bdev->bd_disk->private_data;
 134         tr = dev->tr;
 135
 136         if (!try_module_get(dev->mtd->owner))
 137                 goto out;
 138
 139         if (!try_module_get(tr->owner))
 140                 goto out_tr;
 141
 142         /* FIXME: Locking. A hot pluggable device can go away
 143            (del_mtd_device can be called for it) without its module
 144            being unloaded. */
 145         dev->mtd->usecount++;
 146
 147         ret = 0;
 148         if (tr->open && (ret = tr->open(dev))) {
 149                 dev->mtd->usecount--;
 150                 module_put(dev->mtd->owner);
 151         out_tr:
 152                 module_put(tr->owner);
 153         }
 154  out:
 155         return ret;
 156 }
 157
 158 static int blktrans_release(struct inode *i, struct file *f)
 159 {
 160         struct mtd_blktrans_dev *dev;
 161         struct mtd_blktrans_ops *tr;
 162         int ret = 0;
 163
 164         dev = i->i_bdev->bd_disk->private_data;
 165         tr = dev->tr;
 166
 167         if (tr->release)
 168                 ret = tr->release(dev);
 169
 170         if (!ret) {
 171                 dev->mtd->usecount--;
 172                 module_put(dev->mtd->owner);
 173                 module_put(tr->owner);
 174         }
 175
 176         return ret;
 177 }
 178
 179 static int blktrans_getgeo(struct block_device *bdev, struct hd_geometry *geo)
 180 {
 181         struct mtd_blktrans_dev *dev = bdev->bd_disk->private_data;
 182
 183         if (dev->tr->getgeo)
 184                 return dev->tr->getgeo(dev, geo);
 185         return -ENOTTY;
 186 }
 187
 188 static int blktrans_ioctl(struct inode *inode, struct file *file,
 189                               unsigned int cmd, unsigned long arg)
 190 {
 191         struct mtd_blktrans_dev *dev = inode->i_bdev->bd_disk->private_data;
 192         struct mtd_blktrans_ops *tr = dev->tr;
 193
 194         switch (cmd) {
 195         case BLKFLSBUF:
 196                 if (tr->flush)
 197                         return tr->flush(dev);
 198                 /* The core code did the work, we had nothing to do. */
 199                 return 0;
 200         default:
 201                 return -ENOTTY;
 202         }
 203 }
 204
 205 struct block_device_operations mtd_blktrans_ops = {
 206         .owner          = THIS_MODULE,
 207         .open           = blktrans_open,
 208         .release        = blktrans_release,
 209         .ioctl          = blktrans_ioctl,
 210         .getgeo         = blktrans_getgeo,
 211 };
 212
 213 int add_mtd_blktrans_dev(struct mtd_blktrans_dev *new)
 214 {
 215         struct mtd_blktrans_ops *tr = new->tr;
 216         struct list_head *this;
 217         int last_devnum = -1;
 218         struct gendisk *gd;
 219
 220         if (mutex_trylock(&mtd_table_mutex)) {
 221                 mutex_unlock(&mtd_table_mutex);
 222                 BUG();
 223         }
 224
 225         list_for_each(this, &tr->devs) {
 226                 struct mtd_blktrans_dev *d = list_entry(this, struct mtd_blktrans_dev, list);
 227                 if (new->devnum == -1) {
 228                         /* Use first free number */
 229                         if (d->devnum != last_devnum+1) {
 230                                 /* Found a free devnum. Plug it in here */
 231                                 new->devnum = last_devnum+1;
 232                                 list_add_tail(&new->list, &d->list);
 233                                 goto added;
 234                         }
 235                 } else if (d->devnum == new->devnum) {
 236                         /* Required number taken */
 237                         return -EBUSY;
 238                 } else if (d->devnum > new->devnum) {
 239                         /* Required number was free */
 240                         list_add_tail(&new->list, &d->list);
 241                         goto added;
 242                 }
 243                 last_devnum = d->devnum;
 244         }
 245         if (new->devnum == -1)
 246                 new->devnum = last_devnum+1;
 247
 248         if ((new->devnum << tr->part_bits) > 256) {
 249                 return -EBUSY;
 250         }
 251
 252         mutex_init(&new->lock);
 253         list_add_tail(&new->list, &tr->devs);
 254  added:
 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
 288         if (new->readonly)
 289                 set_disk_ro(gd, 1);
 290
 291         add_disk(gd);
 292
 293         return 0;
 294 }
 295
 296 int del_mtd_blktrans_dev(struct mtd_blktrans_dev *old)
 297 {
 298         if (mutex_trylock(&mtd_table_mutex)) {
 299                 mutex_unlock(&mtd_table_mutex);
 300                 BUG();
 301         }
 302
 303         list_del(&old->list);
 304
 305         del_gendisk(old->blkcore_priv);
 306         put_disk(old->blkcore_priv);
 307
 308         return 0;
 309 }
 310
 311 static void blktrans_notify_remove(struct mtd_info *mtd)
 312 {
 313         struct list_head *this, *this2, *next;
 314
 315         list_for_each(this, &blktrans_majors) {
 316                 struct mtd_blktrans_ops *tr = list_entry(this, struct mtd_blktrans_ops, list);
 317
 318                 list_for_each_safe(this2, next, &tr->devs) {
 319                         struct mtd_blktrans_dev *dev = list_entry(this2, struct mtd_blktrans_dev, list);
 320
 321                         if (dev->mtd == mtd)
 322                                 tr->remove_dev(dev);
 323                 }
 324         }
 325 }
 326
 327 static void blktrans_notify_add(struct mtd_info *mtd)
 328 {
 329         struct list_head *this;
 330
 331         if (mtd->type == MTD_ABSENT)
 332                 return;
 333
 334         list_for_each(this, &blktrans_majors) {
 335                 struct mtd_blktrans_ops *tr = list_entry(this, struct mtd_blktrans_ops, list);
 336
 337                 tr->add_mtd(tr, mtd);
 338         }
 339
 340 }
 341
 342 static struct mtd_notifier blktrans_notifier = {
 343         .add = blktrans_notify_add,
 344         .remove = blktrans_notify_remove,
 345 };
 346
 347 int register_mtd_blktrans(struct mtd_blktrans_ops *tr)
 348 {
 349         int ret, i;
 350
 351         /* Register the notifier if/when the first device type is
 352            registered, to prevent the link/init ordering from fucking
 353            us over. */
 354         if (!blktrans_notifier.list.next)
 355                 register_mtd_user(&blktrans_notifier);
 356
 357         tr->blkcore_priv = kzalloc(sizeof(*tr->blkcore_priv), GFP_KERNEL);
 358         if (!tr->blkcore_priv)
 359                 return -ENOMEM;
 360
 361         mutex_lock(&mtd_table_mutex);
 362
 363         ret = register_blkdev(tr->major, tr->name);
 364         if (ret) {
 365                 printk(KERN_WARNING "Unable to register %s block device on major %d: %d\n",
 366                        tr->name, tr->major, ret);
 367                 kfree(tr->blkcore_priv);
 368                 mutex_unlock(&mtd_table_mutex);
 369                 return ret;
 370         }
 371         spin_lock_init(&tr->blkcore_priv->queue_lock);
 372
 373         tr->blkcore_priv->rq = blk_init_queue(mtd_blktrans_request, &tr->blkcore_priv->queue_lock);
 374         if (!tr->blkcore_priv->rq) {
 375                 unregister_blkdev(tr->major, tr->name);
 376                 kfree(tr->blkcore_priv);
 377                 mutex_unlock(&mtd_table_mutex);
 378                 return -ENOMEM;
 379         }
 380
 381         tr->blkcore_priv->rq->queuedata = tr;
 382         blk_queue_hardsect_size(tr->blkcore_priv->rq, tr->blksize);
 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                 blk_cleanup_queue(tr->blkcore_priv->rq);
 389                 unregister_blkdev(tr->major, tr->name);
 390                 kfree(tr->blkcore_priv);
 391                 mutex_unlock(&mtd_table_mutex);
 392                 return PTR_ERR(tr->blkcore_priv->thread);
 393         }
 394
 395         INIT_LIST_HEAD(&tr->devs);
 396         list_add(&tr->list, &blktrans_majors);
 397
 398         for (i=0; i<MAX_MTD_DEVICES; i++) {
 399                 if (mtd_table[i] && mtd_table[i]->type != MTD_ABSENT)
 400                         tr->add_mtd(tr, mtd_table[i]);
 401         }
 402
 403         mutex_unlock(&mtd_table_mutex);
 404
 405         return 0;
 406 }
 407
 408 int deregister_mtd_blktrans(struct mtd_blktrans_ops *tr)
 409 {
 410         struct list_head *this, *next;
 411
 412         mutex_lock(&mtd_table_mutex);
 413
 414         /* Clean up the kernel thread */
 415         kthread_stop(tr->blkcore_priv->thread);
 416
 417         /* Remove it from the list of active majors */
 418         list_del(&tr->list);
 419
 420         list_for_each_safe(this, next, &tr->devs) {
 421                 struct mtd_blktrans_dev *dev = list_entry(this, struct mtd_blktrans_dev, list);
 422                 tr->remove_dev(dev);
 423         }
 424
 425         blk_cleanup_queue(tr->blkcore_priv->rq);
 426         unregister_blkdev(tr->major, tr->name);
 427
 428         mutex_unlock(&mtd_table_mutex);
 429
 430         kfree(tr->blkcore_priv);
 431
 432         BUG_ON(!list_empty(&tr->devs));
 433         return 0;
 434 }
 435
 436 static void __exit mtd_blktrans_exit(void)
 437 {
 438         /* No race here -- if someone's currently in register_mtd_blktrans
 439            we're screwed anyway. */
 440         if (blktrans_notifier.list.next)
 441                 unregister_mtd_user(&blktrans_notifier);
 442 }
 443
 444 module_exit(mtd_blktrans_exit);
 445
 446 EXPORT_SYMBOL_GPL(register_mtd_blktrans);
 447 EXPORT_SYMBOL_GPL(deregister_mtd_blktrans);
 448 EXPORT_SYMBOL_GPL(add_mtd_blktrans_dev);
 449 EXPORT_SYMBOL_GPL(del_mtd_blktrans_dev);
 450
 451 MODULE_AUTHOR("David Woodhouse <dwmw2@infradead.org>");
 452 MODULE_LICENSE("GPL");
 453 MODULE_DESCRIPTION("Common interface to block layer for MTD 'translation layers'");