Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1 | /* |
| 2 | * $Id: mtd_blkdevs.c,v 1.24 2004/11/16 18:28:59 dwmw2 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 <asm/semaphore.h> |
| 23 | #include <asm/uaccess.h> |
| 24 | #include <linux/devfs_fs_kernel.h> |
| 25 | |
| 26 | static LIST_HEAD(blktrans_majors); |
| 27 | |
| 28 | extern struct semaphore mtd_table_mutex; |
| 29 | extern struct mtd_info *mtd_table[]; |
| 30 | |
| 31 | struct mtd_blkcore_priv { |
| 32 | struct completion thread_dead; |
| 33 | int exiting; |
| 34 | wait_queue_head_t thread_wq; |
| 35 | struct request_queue *rq; |
| 36 | spinlock_t queue_lock; |
| 37 | }; |
| 38 | |
| 39 | static int do_blktrans_request(struct mtd_blktrans_ops *tr, |
| 40 | struct mtd_blktrans_dev *dev, |
| 41 | struct request *req) |
| 42 | { |
| 43 | unsigned long block, nsect; |
| 44 | char *buf; |
| 45 | |
| 46 | block = req->sector; |
| 47 | nsect = req->current_nr_sectors; |
| 48 | buf = req->buffer; |
| 49 | |
| 50 | if (!(req->flags & REQ_CMD)) |
| 51 | return 0; |
| 52 | |
| 53 | if (block + nsect > 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 += 512) |
| 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 += 512) |
| 68 | if (tr->writesect(dev, block, buf)) |
| 69 | return 0; |
| 70 | return 1; |
| 71 | |
| 72 | default: |
| 73 | printk(KERN_NOTICE "Unknown request %ld\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 | PF_NOFREEZE; |
| 85 | |
| 86 | daemonize("%sd", tr->name); |
| 87 | |
| 88 | /* daemonize() doesn't do this for us since some kernel threads |
| 89 | actually want to deal with signals. We can't just call |
| 90 | exit_sighand() since that'll cause an oops when we finally |
| 91 | do exit. */ |
| 92 | spin_lock_irq(¤t->sighand->siglock); |
| 93 | sigfillset(¤t->blocked); |
| 94 | recalc_sigpending(); |
| 95 | spin_unlock_irq(¤t->sighand->siglock); |
| 96 | |
| 97 | spin_lock_irq(rq->queue_lock); |
| 98 | |
| 99 | while (!tr->blkcore_priv->exiting) { |
| 100 | struct request *req; |
| 101 | struct mtd_blktrans_dev *dev; |
| 102 | int res = 0; |
| 103 | DECLARE_WAITQUEUE(wait, current); |
| 104 | |
| 105 | req = elv_next_request(rq); |
| 106 | |
| 107 | if (!req) { |
| 108 | add_wait_queue(&tr->blkcore_priv->thread_wq, &wait); |
| 109 | set_current_state(TASK_INTERRUPTIBLE); |
| 110 | |
| 111 | spin_unlock_irq(rq->queue_lock); |
| 112 | |
| 113 | schedule(); |
| 114 | remove_wait_queue(&tr->blkcore_priv->thread_wq, &wait); |
| 115 | |
| 116 | spin_lock_irq(rq->queue_lock); |
| 117 | |
| 118 | continue; |
| 119 | } |
| 120 | |
| 121 | dev = req->rq_disk->private_data; |
| 122 | tr = dev->tr; |
| 123 | |
| 124 | spin_unlock_irq(rq->queue_lock); |
| 125 | |
| 126 | down(&dev->sem); |
| 127 | res = do_blktrans_request(tr, dev, req); |
| 128 | up(&dev->sem); |
| 129 | |
| 130 | spin_lock_irq(rq->queue_lock); |
| 131 | |
| 132 | end_request(req, res); |
| 133 | } |
| 134 | spin_unlock_irq(rq->queue_lock); |
| 135 | |
| 136 | complete_and_exit(&tr->blkcore_priv->thread_dead, 0); |
| 137 | } |
| 138 | |
| 139 | static void mtd_blktrans_request(struct request_queue *rq) |
| 140 | { |
| 141 | struct mtd_blktrans_ops *tr = rq->queuedata; |
| 142 | wake_up(&tr->blkcore_priv->thread_wq); |
| 143 | } |
| 144 | |
| 145 | |
| 146 | static int blktrans_open(struct inode *i, struct file *f) |
| 147 | { |
| 148 | struct mtd_blktrans_dev *dev; |
| 149 | struct mtd_blktrans_ops *tr; |
| 150 | int ret = -ENODEV; |
| 151 | |
| 152 | dev = i->i_bdev->bd_disk->private_data; |
| 153 | tr = dev->tr; |
| 154 | |
| 155 | if (!try_module_get(dev->mtd->owner)) |
| 156 | goto out; |
| 157 | |
| 158 | if (!try_module_get(tr->owner)) |
| 159 | goto out_tr; |
| 160 | |
| 161 | /* FIXME: Locking. A hot pluggable device can go away |
| 162 | (del_mtd_device can be called for it) without its module |
| 163 | being unloaded. */ |
| 164 | dev->mtd->usecount++; |
| 165 | |
| 166 | ret = 0; |
| 167 | if (tr->open && (ret = tr->open(dev))) { |
| 168 | dev->mtd->usecount--; |
| 169 | module_put(dev->mtd->owner); |
| 170 | out_tr: |
| 171 | module_put(tr->owner); |
| 172 | } |
| 173 | out: |
| 174 | return ret; |
| 175 | } |
| 176 | |
| 177 | static int blktrans_release(struct inode *i, struct file *f) |
| 178 | { |
| 179 | struct mtd_blktrans_dev *dev; |
| 180 | struct mtd_blktrans_ops *tr; |
| 181 | int ret = 0; |
| 182 | |
| 183 | dev = i->i_bdev->bd_disk->private_data; |
| 184 | tr = dev->tr; |
| 185 | |
| 186 | if (tr->release) |
| 187 | ret = tr->release(dev); |
| 188 | |
| 189 | if (!ret) { |
| 190 | dev->mtd->usecount--; |
| 191 | module_put(dev->mtd->owner); |
| 192 | module_put(tr->owner); |
| 193 | } |
| 194 | |
| 195 | return ret; |
| 196 | } |
| 197 | |
| 198 | |
| 199 | static int blktrans_ioctl(struct inode *inode, struct file *file, |
| 200 | unsigned int cmd, unsigned long arg) |
| 201 | { |
| 202 | struct mtd_blktrans_dev *dev = inode->i_bdev->bd_disk->private_data; |
| 203 | struct mtd_blktrans_ops *tr = dev->tr; |
| 204 | |
| 205 | switch (cmd) { |
| 206 | case BLKFLSBUF: |
| 207 | if (tr->flush) |
| 208 | return tr->flush(dev); |
| 209 | /* The core code did the work, we had nothing to do. */ |
| 210 | return 0; |
| 211 | |
| 212 | case HDIO_GETGEO: |
| 213 | if (tr->getgeo) { |
| 214 | struct hd_geometry g; |
| 215 | int ret; |
| 216 | |
| 217 | memset(&g, 0, sizeof(g)); |
| 218 | ret = tr->getgeo(dev, &g); |
| 219 | if (ret) |
| 220 | return ret; |
| 221 | |
| 222 | g.start = get_start_sect(inode->i_bdev); |
| 223 | if (copy_to_user((void __user *)arg, &g, sizeof(g))) |
| 224 | return -EFAULT; |
| 225 | return 0; |
| 226 | } /* else */ |
| 227 | default: |
| 228 | return -ENOTTY; |
| 229 | } |
| 230 | } |
| 231 | |
| 232 | struct block_device_operations mtd_blktrans_ops = { |
| 233 | .owner = THIS_MODULE, |
| 234 | .open = blktrans_open, |
| 235 | .release = blktrans_release, |
| 236 | .ioctl = blktrans_ioctl, |
| 237 | }; |
| 238 | |
| 239 | int add_mtd_blktrans_dev(struct mtd_blktrans_dev *new) |
| 240 | { |
| 241 | struct mtd_blktrans_ops *tr = new->tr; |
| 242 | struct list_head *this; |
| 243 | int last_devnum = -1; |
| 244 | struct gendisk *gd; |
| 245 | |
| 246 | if (!down_trylock(&mtd_table_mutex)) { |
| 247 | up(&mtd_table_mutex); |
| 248 | BUG(); |
| 249 | } |
| 250 | |
| 251 | list_for_each(this, &tr->devs) { |
| 252 | struct mtd_blktrans_dev *d = list_entry(this, struct mtd_blktrans_dev, list); |
| 253 | if (new->devnum == -1) { |
| 254 | /* Use first free number */ |
| 255 | if (d->devnum != last_devnum+1) { |
| 256 | /* Found a free devnum. Plug it in here */ |
| 257 | new->devnum = last_devnum+1; |
| 258 | list_add_tail(&new->list, &d->list); |
| 259 | goto added; |
| 260 | } |
| 261 | } else if (d->devnum == new->devnum) { |
| 262 | /* Required number taken */ |
| 263 | return -EBUSY; |
| 264 | } else if (d->devnum > new->devnum) { |
| 265 | /* Required number was free */ |
| 266 | list_add_tail(&new->list, &d->list); |
| 267 | goto added; |
| 268 | } |
| 269 | last_devnum = d->devnum; |
| 270 | } |
| 271 | if (new->devnum == -1) |
| 272 | new->devnum = last_devnum+1; |
| 273 | |
| 274 | if ((new->devnum << tr->part_bits) > 256) { |
| 275 | return -EBUSY; |
| 276 | } |
| 277 | |
| 278 | init_MUTEX(&new->sem); |
| 279 | list_add_tail(&new->list, &tr->devs); |
| 280 | added: |
| 281 | if (!tr->writesect) |
| 282 | new->readonly = 1; |
| 283 | |
| 284 | gd = alloc_disk(1 << tr->part_bits); |
| 285 | if (!gd) { |
| 286 | list_del(&new->list); |
| 287 | return -ENOMEM; |
| 288 | } |
| 289 | gd->major = tr->major; |
| 290 | gd->first_minor = (new->devnum) << tr->part_bits; |
| 291 | gd->fops = &mtd_blktrans_ops; |
| 292 | |
| 293 | snprintf(gd->disk_name, sizeof(gd->disk_name), |
| 294 | "%s%c", tr->name, (tr->part_bits?'a':'0') + new->devnum); |
| 295 | snprintf(gd->devfs_name, sizeof(gd->devfs_name), |
| 296 | "%s/%c", tr->name, (tr->part_bits?'a':'0') + new->devnum); |
| 297 | |
| 298 | /* 2.5 has capacity in units of 512 bytes while still |
| 299 | having BLOCK_SIZE_BITS set to 10. Just to keep us amused. */ |
| 300 | set_capacity(gd, (new->size * new->blksize) >> 9); |
| 301 | |
| 302 | gd->private_data = new; |
| 303 | new->blkcore_priv = gd; |
| 304 | gd->queue = tr->blkcore_priv->rq; |
| 305 | |
| 306 | if (new->readonly) |
| 307 | set_disk_ro(gd, 1); |
| 308 | |
| 309 | add_disk(gd); |
| 310 | |
| 311 | return 0; |
| 312 | } |
| 313 | |
| 314 | int del_mtd_blktrans_dev(struct mtd_blktrans_dev *old) |
| 315 | { |
| 316 | if (!down_trylock(&mtd_table_mutex)) { |
| 317 | up(&mtd_table_mutex); |
| 318 | BUG(); |
| 319 | } |
| 320 | |
| 321 | list_del(&old->list); |
| 322 | |
| 323 | del_gendisk(old->blkcore_priv); |
| 324 | put_disk(old->blkcore_priv); |
| 325 | |
| 326 | return 0; |
| 327 | } |
| 328 | |
| 329 | static void blktrans_notify_remove(struct mtd_info *mtd) |
| 330 | { |
| 331 | struct list_head *this, *this2, *next; |
| 332 | |
| 333 | list_for_each(this, &blktrans_majors) { |
| 334 | struct mtd_blktrans_ops *tr = list_entry(this, struct mtd_blktrans_ops, list); |
| 335 | |
| 336 | list_for_each_safe(this2, next, &tr->devs) { |
| 337 | struct mtd_blktrans_dev *dev = list_entry(this2, struct mtd_blktrans_dev, list); |
| 338 | |
| 339 | if (dev->mtd == mtd) |
| 340 | tr->remove_dev(dev); |
| 341 | } |
| 342 | } |
| 343 | } |
| 344 | |
| 345 | static void blktrans_notify_add(struct mtd_info *mtd) |
| 346 | { |
| 347 | struct list_head *this; |
| 348 | |
| 349 | if (mtd->type == MTD_ABSENT) |
| 350 | return; |
| 351 | |
| 352 | list_for_each(this, &blktrans_majors) { |
| 353 | struct mtd_blktrans_ops *tr = list_entry(this, struct mtd_blktrans_ops, list); |
| 354 | |
| 355 | tr->add_mtd(tr, mtd); |
| 356 | } |
| 357 | |
| 358 | } |
| 359 | |
| 360 | static struct mtd_notifier blktrans_notifier = { |
| 361 | .add = blktrans_notify_add, |
| 362 | .remove = blktrans_notify_remove, |
| 363 | }; |
| 364 | |
| 365 | int register_mtd_blktrans(struct mtd_blktrans_ops *tr) |
| 366 | { |
| 367 | int ret, i; |
| 368 | |
| 369 | /* Register the notifier if/when the first device type is |
| 370 | registered, to prevent the link/init ordering from fucking |
| 371 | us over. */ |
| 372 | if (!blktrans_notifier.list.next) |
| 373 | register_mtd_user(&blktrans_notifier); |
| 374 | |
| 375 | tr->blkcore_priv = kmalloc(sizeof(*tr->blkcore_priv), GFP_KERNEL); |
| 376 | if (!tr->blkcore_priv) |
| 377 | return -ENOMEM; |
| 378 | |
| 379 | memset(tr->blkcore_priv, 0, sizeof(*tr->blkcore_priv)); |
| 380 | |
| 381 | down(&mtd_table_mutex); |
| 382 | |
| 383 | ret = register_blkdev(tr->major, tr->name); |
| 384 | if (ret) { |
| 385 | printk(KERN_WARNING "Unable to register %s block device on major %d: %d\n", |
| 386 | tr->name, tr->major, ret); |
| 387 | kfree(tr->blkcore_priv); |
| 388 | up(&mtd_table_mutex); |
| 389 | return ret; |
| 390 | } |
| 391 | spin_lock_init(&tr->blkcore_priv->queue_lock); |
| 392 | init_completion(&tr->blkcore_priv->thread_dead); |
| 393 | init_waitqueue_head(&tr->blkcore_priv->thread_wq); |
| 394 | |
| 395 | tr->blkcore_priv->rq = blk_init_queue(mtd_blktrans_request, &tr->blkcore_priv->queue_lock); |
| 396 | if (!tr->blkcore_priv->rq) { |
| 397 | unregister_blkdev(tr->major, tr->name); |
| 398 | kfree(tr->blkcore_priv); |
| 399 | up(&mtd_table_mutex); |
| 400 | return -ENOMEM; |
| 401 | } |
| 402 | |
| 403 | tr->blkcore_priv->rq->queuedata = tr; |
| 404 | |
| 405 | ret = kernel_thread(mtd_blktrans_thread, tr, CLONE_KERNEL); |
| 406 | if (ret < 0) { |
| 407 | blk_cleanup_queue(tr->blkcore_priv->rq); |
| 408 | unregister_blkdev(tr->major, tr->name); |
| 409 | kfree(tr->blkcore_priv); |
| 410 | up(&mtd_table_mutex); |
| 411 | return ret; |
| 412 | } |
| 413 | |
| 414 | devfs_mk_dir(tr->name); |
| 415 | |
| 416 | INIT_LIST_HEAD(&tr->devs); |
| 417 | list_add(&tr->list, &blktrans_majors); |
| 418 | |
| 419 | for (i=0; i<MAX_MTD_DEVICES; i++) { |
| 420 | if (mtd_table[i] && mtd_table[i]->type != MTD_ABSENT) |
| 421 | tr->add_mtd(tr, mtd_table[i]); |
| 422 | } |
| 423 | |
| 424 | up(&mtd_table_mutex); |
| 425 | |
| 426 | return 0; |
| 427 | } |
| 428 | |
| 429 | int deregister_mtd_blktrans(struct mtd_blktrans_ops *tr) |
| 430 | { |
| 431 | struct list_head *this, *next; |
| 432 | |
| 433 | down(&mtd_table_mutex); |
| 434 | |
| 435 | /* Clean up the kernel thread */ |
| 436 | tr->blkcore_priv->exiting = 1; |
| 437 | wake_up(&tr->blkcore_priv->thread_wq); |
| 438 | wait_for_completion(&tr->blkcore_priv->thread_dead); |
| 439 | |
| 440 | /* Remove it from the list of active majors */ |
| 441 | list_del(&tr->list); |
| 442 | |
| 443 | list_for_each_safe(this, next, &tr->devs) { |
| 444 | struct mtd_blktrans_dev *dev = list_entry(this, struct mtd_blktrans_dev, list); |
| 445 | tr->remove_dev(dev); |
| 446 | } |
| 447 | |
| 448 | devfs_remove(tr->name); |
| 449 | blk_cleanup_queue(tr->blkcore_priv->rq); |
| 450 | unregister_blkdev(tr->major, tr->name); |
| 451 | |
| 452 | up(&mtd_table_mutex); |
| 453 | |
| 454 | kfree(tr->blkcore_priv); |
| 455 | |
| 456 | if (!list_empty(&tr->devs)) |
| 457 | BUG(); |
| 458 | return 0; |
| 459 | } |
| 460 | |
| 461 | static void __exit mtd_blktrans_exit(void) |
| 462 | { |
| 463 | /* No race here -- if someone's currently in register_mtd_blktrans |
| 464 | we're screwed anyway. */ |
| 465 | if (blktrans_notifier.list.next) |
| 466 | unregister_mtd_user(&blktrans_notifier); |
| 467 | } |
| 468 | |
| 469 | module_exit(mtd_blktrans_exit); |
| 470 | |
| 471 | EXPORT_SYMBOL_GPL(register_mtd_blktrans); |
| 472 | EXPORT_SYMBOL_GPL(deregister_mtd_blktrans); |
| 473 | EXPORT_SYMBOL_GPL(add_mtd_blktrans_dev); |
| 474 | EXPORT_SYMBOL_GPL(del_mtd_blktrans_dev); |
| 475 | |
| 476 | MODULE_AUTHOR("David Woodhouse <dwmw2@infradead.org>"); |
| 477 | MODULE_LICENSE("GPL"); |
| 478 | MODULE_DESCRIPTION("Common interface to block layer for MTD 'translation layers'"); |