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 mtd_blktrans_dev *d;
 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_entry(d, &tr->devs, list) {
 223                 if (new->devnum == -1) {
 224                         /* Use first free number */
 225                         if (d->devnum != last_devnum+1) {
 226                                 /* Found a free devnum. Plug it in here */
 227                                 new->devnum = last_devnum+1;
 228                                 list_add_tail(&new->list, &d->list);
 229                                 goto added;
 230                         }
 231                 } else if (d->devnum == new->devnum) {
 232                         /* Required number taken */
 233                         return -EBUSY;
 234                 } else if (d->devnum > new->devnum) {
 235                         /* Required number was free */
 236                         list_add_tail(&new->list, &d->list);
 237                         goto added;
 238                 }
 239                 last_devnum = d->devnum;
 240         }
 241         if (new->devnum == -1)
 242                 new->devnum = last_devnum+1;
 243
 244         if ((new->devnum << tr->part_bits) > 256) {
 245                 return -EBUSY;
 246         }
 247
 248         list_add_tail(&new->list, &tr->devs);
 249  added:
 250         mutex_init(&new->lock);
 251         if (!tr->writesect)
 252                 new->readonly = 1;
 253
 254         gd = alloc_disk(1 << tr->part_bits);
 255         if (!gd) {
 256                 list_del(&new->list);
 257                 return -ENOMEM;
 258         }
 259         gd->major = tr->major;
 260         gd->first_minor = (new->devnum) << tr->part_bits;
 261         gd->fops = &mtd_blktrans_ops;
 262
 263         if (tr->part_bits)
 264                 if (new->devnum < 26)
 265                         snprintf(gd->disk_name, sizeof(gd->disk_name),
 266                                  "%s%c", tr->name, 'a' + new->devnum);
 267                 else
 268                         snprintf(gd->disk_name, sizeof(gd->disk_name),
 269                                  "%s%c%c", tr->name,
 270                                  'a' - 1 + new->devnum / 26,
 271                                  'a' + new->devnum % 26);
 272         else
 273                 snprintf(gd->disk_name, sizeof(gd->disk_name),
 274                          "%s%d", tr->name, new->devnum);
 275
 276         /* 2.5 has capacity in units of 512 bytes while still
 277            having BLOCK_SIZE_BITS set to 10. Just to keep us amused. */
 278         set_capacity(gd, (new->size * tr->blksize) >> 9);
 279
 280         gd->private_data = new;
 281         new->blkcore_priv = gd;
 282         gd->queue = tr->blkcore_priv->rq;
 283
 284         if (new->readonly)
 285                 set_disk_ro(gd, 1);
 286
 287         add_disk(gd);
 288
 289         return 0;
 290 }
 291
 292 int del_mtd_blktrans_dev(struct mtd_blktrans_dev *old)
 293 {
 294         if (mutex_trylock(&mtd_table_mutex)) {
 295                 mutex_unlock(&mtd_table_mutex);
 296                 BUG();
 297         }
 298
 299         list_del(&old->list);
 300
 301         del_gendisk(old->blkcore_priv);
 302         put_disk(old->blkcore_priv);
 303
 304         return 0;
 305 }
 306
 307 static void blktrans_notify_remove(struct mtd_info *mtd)
 308 {
 309         struct mtd_blktrans_ops *tr;
 310         struct mtd_blktrans_dev *dev, *next;
 311
 312         list_for_each_entry(tr, &blktrans_majors, list)
 313                 list_for_each_entry_safe(dev, next, &tr->devs, list)
 314                         if (dev->mtd == mtd)
 315                                 tr->remove_dev(dev);
 316 }
 317
 318 static void blktrans_notify_add(struct mtd_info *mtd)
 319 {
 320         struct mtd_blktrans_ops *tr;
 321
 322         if (mtd->type == MTD_ABSENT)
 323                 return;
 324
 325         list_for_each_entry(tr, &blktrans_majors, list)
 326                 tr->add_mtd(tr, mtd);
 327 }
 328
 329 static struct mtd_notifier blktrans_notifier = {
 330         .add = blktrans_notify_add,
 331         .remove = blktrans_notify_remove,
 332 };
 333
 334 int register_mtd_blktrans(struct mtd_blktrans_ops *tr)
 335 {
 336         int ret, i;
 337
 338         /* Register the notifier if/when the first device type is
 339            registered, to prevent the link/init ordering from fucking
 340            us over. */
 341         if (!blktrans_notifier.list.next)
 342                 register_mtd_user(&blktrans_notifier);
 343
 344         tr->blkcore_priv = kzalloc(sizeof(*tr->blkcore_priv), GFP_KERNEL);
 345         if (!tr->blkcore_priv)
 346                 return -ENOMEM;
 347
 348         mutex_lock(&mtd_table_mutex);
 349
 350         ret = register_blkdev(tr->major, tr->name);
 351         if (ret) {
 352                 printk(KERN_WARNING "Unable to register %s block device on major %d: %d\n",
 353                        tr->name, tr->major, ret);
 354                 kfree(tr->blkcore_priv);
 355                 mutex_unlock(&mtd_table_mutex);
 356                 return ret;
 357         }
 358         spin_lock_init(&tr->blkcore_priv->queue_lock);
 359
 360         tr->blkcore_priv->rq = blk_init_queue(mtd_blktrans_request, &tr->blkcore_priv->queue_lock);
 361         if (!tr->blkcore_priv->rq) {
 362                 unregister_blkdev(tr->major, tr->name);
 363                 kfree(tr->blkcore_priv);
 364                 mutex_unlock(&mtd_table_mutex);
 365                 return -ENOMEM;
 366         }
 367
 368         tr->blkcore_priv->rq->queuedata = tr;
 369         blk_queue_hardsect_size(tr->blkcore_priv->rq, tr->blksize);
 370         tr->blkshift = ffs(tr->blksize) - 1;
 371
 372         tr->blkcore_priv->thread = kthread_run(mtd_blktrans_thread, tr,
 373                         "%sd", tr->name);
 374         if (IS_ERR(tr->blkcore_priv->thread)) {
 375                 blk_cleanup_queue(tr->blkcore_priv->rq);
 376                 unregister_blkdev(tr->major, tr->name);
 377                 kfree(tr->blkcore_priv);
 378                 mutex_unlock(&mtd_table_mutex);
 379                 return PTR_ERR(tr->blkcore_priv->thread);
 380         }
 381
 382         INIT_LIST_HEAD(&tr->devs);
 383         list_add(&tr->list, &blktrans_majors);
 384
 385         for (i=0; i<MAX_MTD_DEVICES; i++) {
 386                 if (mtd_table[i] && mtd_table[i]->type != MTD_ABSENT)
 387                         tr->add_mtd(tr, mtd_table[i]);
 388         }
 389
 390         mutex_unlock(&mtd_table_mutex);
 391
 392         return 0;
 393 }
 394
 395 int deregister_mtd_blktrans(struct mtd_blktrans_ops *tr)
 396 {
 397         struct mtd_blktrans_dev *dev, *next;
 398
 399         mutex_lock(&mtd_table_mutex);
 400
 401         /* Clean up the kernel thread */
 402         kthread_stop(tr->blkcore_priv->thread);
 403
 404         /* Remove it from the list of active majors */
 405         list_del(&tr->list);
 406
 407         list_for_each_entry_safe(dev, next, &tr->devs, list)
 408                 tr->remove_dev(dev);
 409
 410         blk_cleanup_queue(tr->blkcore_priv->rq);
 411         unregister_blkdev(tr->major, tr->name);
 412
 413         mutex_unlock(&mtd_table_mutex);
 414
 415         kfree(tr->blkcore_priv);
 416
 417         BUG_ON(!list_empty(&tr->devs));
 418         return 0;
 419 }
 420
 421 static void __exit mtd_blktrans_exit(void)
 422 {
 423         /* No race here -- if someone's currently in register_mtd_blktrans
 424            we're screwed anyway. */
 425         if (blktrans_notifier.list.next)
 426                 unregister_mtd_user(&blktrans_notifier);
 427 }
 428
 429 module_exit(mtd_blktrans_exit);
 430
 431 EXPORT_SYMBOL_GPL(register_mtd_blktrans);
 432 EXPORT_SYMBOL_GPL(deregister_mtd_blktrans);
 433 EXPORT_SYMBOL_GPL(add_mtd_blktrans_dev);
 434 EXPORT_SYMBOL_GPL(del_mtd_blktrans_dev);
 435
 436 MODULE_AUTHOR("David Woodhouse <dwmw2@infradead.org>");
 437 MODULE_LICENSE("GPL");
 438 MODULE_DESCRIPTION("Common interface to block layer for MTD 'translation layers'");