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 = req->sector << 9 >> tr->blkshift;
  43         nsect = req->current_nr_sectors << 9 >> tr->blkshift;
  44
  45         buf = req->buffer;
  46
  47         if (!blk_fs_request(req))
  48                 return 0;
  49
  50         if (req->sector + req->current_nr_sectors > get_capacity(req->rq_disk))
  51                 return 0;
  52
  53         switch(rq_data_dir(req)) {
  54         case READ:
  55                 for (; nsect > 0; nsect--, block++, buf += tr->blksize)
  56                         if (tr->readsect(dev, block, buf))
  57                                 return 0;
  58                 return 1;
  59
  60         case WRITE:
  61                 if (!tr->writesect)
  62                         return 0;
  63
  64                 for (; nsect > 0; nsect--, block++, buf += tr->blksize)
  65                         if (tr->writesect(dev, block, buf))
  66                                 return 0;
  67                 return 1;
  68
  69         default:
  70                 printk(KERN_NOTICE "Unknown request %u\n", rq_data_dir(req));
  71                 return 0;
  72         }
  73 }
  74
  75 static int mtd_blktrans_thread(void *arg)
  76 {
  77         struct mtd_blktrans_ops *tr = arg;
  78         struct request_queue *rq = tr->blkcore_priv->rq;
  79
  80         /* we might get involved when memory gets low, so use PF_MEMALLOC */
  81         current->flags |= PF_MEMALLOC;
  82
  83         spin_lock_irq(rq->queue_lock);
  84         while (!kthread_should_stop()) {
  85                 struct request *req;
  86                 struct mtd_blktrans_dev *dev;
  87                 int res = 0;
  88
  89                 req = elv_next_request(rq);
  90
  91                 if (!req) {
  92                         set_current_state(TASK_INTERRUPTIBLE);
  93                         spin_unlock_irq(rq->queue_lock);
  94                         schedule();
  95                         spin_lock_irq(rq->queue_lock);
  96                         continue;
  97                 }
  98
  99                 dev = req->rq_disk->private_data;
 100                 tr = dev->tr;
 101
 102                 spin_unlock_irq(rq->queue_lock);
 103
 104                 mutex_lock(&dev->lock);
 105                 res = do_blktrans_request(tr, dev, req);
 106                 mutex_unlock(&dev->lock);
 107
 108                 spin_lock_irq(rq->queue_lock);
 109
 110                 end_request(req, res);
 111         }
 112         spin_unlock_irq(rq->queue_lock);
 113
 114         return 0;
 115 }
 116
 117 static void mtd_blktrans_request(struct request_queue *rq)
 118 {
 119         struct mtd_blktrans_ops *tr = rq->queuedata;
 120         wake_up_process(tr->blkcore_priv->thread);
 121 }
 122
 123
 124 static int blktrans_open(struct inode *i, struct file *f)
 125 {
 126         struct mtd_blktrans_dev *dev;
 127         struct mtd_blktrans_ops *tr;
 128         int ret = -ENODEV;
 129
 130         dev = i->i_bdev->bd_disk->private_data;
 131         tr = dev->tr;
 132
 133         if (!try_module_get(dev->mtd->owner))
 134                 goto out;
 135
 136         if (!try_module_get(tr->owner))
 137                 goto out_tr;
 138
 139         /* FIXME: Locking. A hot pluggable device can go away
 140            (del_mtd_device can be called for it) without its module
 141            being unloaded. */
 142         dev->mtd->usecount++;
 143
 144         ret = 0;
 145         if (tr->open && (ret = tr->open(dev))) {
 146                 dev->mtd->usecount--;
 147                 module_put(dev->mtd->owner);
 148         out_tr:
 149                 module_put(tr->owner);
 150         }
 151  out:
 152         return ret;
 153 }
 154
 155 static int blktrans_release(struct inode *i, struct file *f)
 156 {
 157         struct mtd_blktrans_dev *dev;
 158         struct mtd_blktrans_ops *tr;
 159         int ret = 0;
 160
 161         dev = i->i_bdev->bd_disk->private_data;
 162         tr = dev->tr;
 163
 164         if (tr->release)
 165                 ret = tr->release(dev);
 166
 167         if (!ret) {
 168                 dev->mtd->usecount--;
 169                 module_put(dev->mtd->owner);
 170                 module_put(tr->owner);
 171         }
 172
 173         return ret;
 174 }
 175
 176 static int blktrans_getgeo(struct block_device *bdev, struct hd_geometry *geo)
 177 {
 178         struct mtd_blktrans_dev *dev = bdev->bd_disk->private_data;
 179
 180         if (dev->tr->getgeo)
 181                 return dev->tr->getgeo(dev, geo);
 182         return -ENOTTY;
 183 }
 184
 185 static int blktrans_ioctl(struct inode *inode, struct file *file,
 186                               unsigned int cmd, unsigned long arg)
 187 {
 188         struct mtd_blktrans_dev *dev = inode->i_bdev->bd_disk->private_data;
 189         struct mtd_blktrans_ops *tr = dev->tr;
 190
 191         switch (cmd) {
 192         case BLKFLSBUF:
 193                 if (tr->flush)
 194                         return tr->flush(dev);
 195                 /* The core code did the work, we had nothing to do. */
 196                 return 0;
 197         default:
 198                 return -ENOTTY;
 199         }
 200 }
 201
 202 static struct block_device_operations mtd_blktrans_ops = {
 203         .owner          = THIS_MODULE,
 204         .open           = blktrans_open,
 205         .release        = blktrans_release,
 206         .ioctl          = blktrans_ioctl,
 207         .getgeo         = blktrans_getgeo,
 208 };
 209
 210 int add_mtd_blktrans_dev(struct mtd_blktrans_dev *new)
 211 {
 212         struct mtd_blktrans_ops *tr = new->tr;
 213         struct list_head *this;
 214         int last_devnum = -1;
 215         struct gendisk *gd;
 216
 217         if (mutex_trylock(&mtd_table_mutex)) {
 218                 mutex_unlock(&mtd_table_mutex);
 219                 BUG();
 220         }
 221
 222         list_for_each(this, &tr->devs) {
 223                 struct mtd_blktrans_dev *d = list_entry(this, struct mtd_blktrans_dev, 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         if ((new->devnum << tr->part_bits) > 256) {
 246                 return -EBUSY;
 247         }
 248
 249         list_add_tail(&new->list, &tr->devs);
 250  added:
 251         mutex_init(&new->lock);
 252         if (!tr->writesect)
 253                 new->readonly = 1;
 254
 255         gd = alloc_disk(1 << tr->part_bits);
 256         if (!gd) {
 257                 list_del(&new->list);
 258                 return -ENOMEM;
 259         }
 260         gd->major = tr->major;
 261         gd->first_minor = (new->devnum) << tr->part_bits;
 262         gd->fops = &mtd_blktrans_ops;
 263
 264         if (tr->part_bits)
 265                 if (new->devnum < 26)
 266                         snprintf(gd->disk_name, sizeof(gd->disk_name),
 267                                  "%s%c", tr->name, 'a' + new->devnum);
 268                 else
 269                         snprintf(gd->disk_name, sizeof(gd->disk_name),
 270                                  "%s%c%c", tr->name,
 271                                  'a' - 1 + new->devnum / 26,
 272                                  'a' + new->devnum % 26);
 273         else
 274                 snprintf(gd->disk_name, sizeof(gd->disk_name),
 275                          "%s%d", tr->name, new->devnum);
 276
 277         /* 2.5 has capacity in units of 512 bytes while still
 278            having BLOCK_SIZE_BITS set to 10. Just to keep us amused. */
 279         set_capacity(gd, (new->size * tr->blksize) >> 9);
 280
 281         gd->private_data = new;
 282         new->blkcore_priv = gd;
 283         gd->queue = tr->blkcore_priv->rq;
 284
 285         if (new->readonly)
 286                 set_disk_ro(gd, 1);
 287
 288         add_disk(gd);
 289
 290         return 0;
 291 }
 292
 293 int del_mtd_blktrans_dev(struct mtd_blktrans_dev *old)
 294 {
 295         if (mutex_trylock(&mtd_table_mutex)) {
 296                 mutex_unlock(&mtd_table_mutex);
 297                 BUG();
 298         }
 299
 300         list_del(&old->list);
 301
 302         del_gendisk(old->blkcore_priv);
 303         put_disk(old->blkcore_priv);
 304
 305         return 0;
 306 }
 307
 308 static void blktrans_notify_remove(struct mtd_info *mtd)
 309 {
 310         struct list_head *this, *this2, *next;
 311
 312         list_for_each(this, &blktrans_majors) {
 313                 struct mtd_blktrans_ops *tr = list_entry(this, struct mtd_blktrans_ops, list);
 314
 315                 list_for_each_safe(this2, next, &tr->devs) {
 316                         struct mtd_blktrans_dev *dev = list_entry(this2, struct mtd_blktrans_dev, list);
 317
 318                         if (dev->mtd == mtd)
 319                                 tr->remove_dev(dev);
 320                 }
 321         }
 322 }
 323
 324 static void blktrans_notify_add(struct mtd_info *mtd)
 325 {
 326         struct list_head *this;
 327
 328         if (mtd->type == MTD_ABSENT)
 329                 return;
 330
 331         list_for_each(this, &blktrans_majors) {
 332                 struct mtd_blktrans_ops *tr = list_entry(this, struct mtd_blktrans_ops, list);
 333
 334                 tr->add_mtd(tr, mtd);
 335         }
 336
 337 }
 338
 339 static struct mtd_notifier blktrans_notifier = {
 340         .add = blktrans_notify_add,
 341         .remove = blktrans_notify_remove,
 342 };
 343
 344 int register_mtd_blktrans(struct mtd_blktrans_ops *tr)
 345 {
 346         int ret, i;
 347
 348         /* Register the notifier if/when the first device type is
 349            registered, to prevent the link/init ordering from fucking
 350            us over. */
 351         if (!blktrans_notifier.list.next)
 352                 register_mtd_user(&blktrans_notifier);
 353
 354         tr->blkcore_priv = kzalloc(sizeof(*tr->blkcore_priv), GFP_KERNEL);
 355         if (!tr->blkcore_priv)
 356                 return -ENOMEM;
 357
 358         mutex_lock(&mtd_table_mutex);
 359
 360         ret = register_blkdev(tr->major, tr->name);
 361         if (ret) {
 362                 printk(KERN_WARNING "Unable to register %s block device on major %d: %d\n",
 363                        tr->name, tr->major, ret);
 364                 kfree(tr->blkcore_priv);
 365                 mutex_unlock(&mtd_table_mutex);
 366                 return ret;
 367         }
 368         spin_lock_init(&tr->blkcore_priv->queue_lock);
 369
 370         tr->blkcore_priv->rq = blk_init_queue(mtd_blktrans_request, &tr->blkcore_priv->queue_lock);
 371         if (!tr->blkcore_priv->rq) {
 372                 unregister_blkdev(tr->major, tr->name);
 373                 kfree(tr->blkcore_priv);
 374                 mutex_unlock(&mtd_table_mutex);
 375                 return -ENOMEM;
 376         }
 377
 378         tr->blkcore_priv->rq->queuedata = tr;
 379         blk_queue_hardsect_size(tr->blkcore_priv->rq, tr->blksize);
 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                 blk_cleanup_queue(tr->blkcore_priv->rq);
 386                 unregister_blkdev(tr->major, tr->name);
 387                 kfree(tr->blkcore_priv);
 388                 mutex_unlock(&mtd_table_mutex);
 389                 return PTR_ERR(tr->blkcore_priv->thread);
 390         }
 391
 392         INIT_LIST_HEAD(&tr->devs);
 393         list_add(&tr->list, &blktrans_majors);
 394
 395         for (i=0; i<MAX_MTD_DEVICES; i++) {
 396                 if (mtd_table[i] && mtd_table[i]->type != MTD_ABSENT)
 397                         tr->add_mtd(tr, mtd_table[i]);
 398         }
 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 list_head *this, *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_safe(this, next, &tr->devs) {
 418                 struct mtd_blktrans_dev *dev = list_entry(this, struct mtd_blktrans_dev, list);
 419                 tr->remove_dev(dev);
 420         }
 421
 422         blk_cleanup_queue(tr->blkcore_priv->rq);
 423         unregister_blkdev(tr->major, tr->name);
 424
 425         mutex_unlock(&mtd_table_mutex);
 426
 427         kfree(tr->blkcore_priv);
 428
 429         BUG_ON(!list_empty(&tr->devs));
 430         return 0;
 431 }
 432
 433 static void __exit mtd_blktrans_exit(void)
 434 {
 435         /* No race here -- if someone's currently in register_mtd_blktrans
 436            we're screwed anyway. */
 437         if (blktrans_notifier.list.next)
 438                 unregister_mtd_user(&blktrans_notifier);
 439 }
 440
 441 module_exit(mtd_blktrans_exit);
 442
 443 EXPORT_SYMBOL_GPL(register_mtd_blktrans);
 444 EXPORT_SYMBOL_GPL(deregister_mtd_blktrans);
 445 EXPORT_SYMBOL_GPL(add_mtd_blktrans_dev);
 446 EXPORT_SYMBOL_GPL(del_mtd_blktrans_dev);
 447
 448 MODULE_AUTHOR("David Woodhouse <dwmw2@infradead.org>");
 449 MODULE_LICENSE("GPL");
 450 MODULE_DESCRIPTION("Common interface to block layer for MTD 'translation layers'");