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 <asm/semaphore.h> 23 #include <asm/uaccess.h> 24 25 static LIST_HEAD(blktrans_majors); 26 27 extern struct semaphore mtd_table_mutex; 28 extern struct mtd_info *mtd_table[]; 29 30 struct mtd_blkcore_priv { 31 struct completion thread_dead; 32 int exiting; 33 wait_queue_head_t thread_wq; 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; 46 nsect = req->current_nr_sectors; 47 buf = req->buffer; 48 49 if (!(req->flags & REQ_CMD)) 50 return 0; 51 52 if (block + nsect > get_capacity(req->rq_disk)) 53 return 0; 54 55 switch(rq_data_dir(req)) { 56 case READ: 57 for (; nsect > 0; nsect--, block++, buf += 512) 58 if (tr->readsect(dev, block, buf)) 59 return 0; 60 return 1; 61 62 case WRITE: 63 if (!tr->writesect) 64 return 0; 65 66 for (; nsect > 0; nsect--, block++, buf += 512) 67 if (tr->writesect(dev, block, buf)) 68 return 0; 69 return 1; 70 71 default: 72 printk(KERN_NOTICE "Unknown request %ld\n", rq_data_dir(req)); 73 return 0; 74 } 75 } 76 77 static int mtd_blktrans_thread(void *arg) 78 { 79 struct mtd_blktrans_ops *tr = arg; 80 struct request_queue *rq = tr->blkcore_priv->rq; 81 82 /* we might get involved when memory gets low, so use PF_MEMALLOC */ 83 current->flags |= PF_MEMALLOC | PF_NOFREEZE; 84 85 daemonize("%sd", tr->name); 86 87 /* daemonize() doesn't do this for us since some kernel threads 88 actually want to deal with signals. We can't just call 89 exit_sighand() since that'll cause an oops when we finally 90 do exit. */ 91 spin_lock_irq(¤t->sighand->siglock); 92 sigfillset(¤t->blocked); 93 recalc_sigpending(); 94 spin_unlock_irq(¤t->sighand->siglock); 95 96 spin_lock_irq(rq->queue_lock); 97 98 while (!tr->blkcore_priv->exiting) { 99 struct request *req; 100 struct mtd_blktrans_dev *dev; 101 int res = 0; 102 DECLARE_WAITQUEUE(wait, current); 103 104 req = elv_next_request(rq); 105 106 if (!req) { 107 add_wait_queue(&tr->blkcore_priv->thread_wq, &wait); 108 set_current_state(TASK_INTERRUPTIBLE); 109 110 spin_unlock_irq(rq->queue_lock); 111 112 schedule(); 113 remove_wait_queue(&tr->blkcore_priv->thread_wq, &wait); 114 115 spin_lock_irq(rq->queue_lock); 116 117 continue; 118 } 119 120 dev = req->rq_disk->private_data; 121 tr = dev->tr; 122 123 spin_unlock_irq(rq->queue_lock); 124 125 down(&dev->sem); 126 res = do_blktrans_request(tr, dev, req); 127 up(&dev->sem); 128 129 spin_lock_irq(rq->queue_lock); 130 131 end_request(req, res); 132 } 133 spin_unlock_irq(rq->queue_lock); 134 135 complete_and_exit(&tr->blkcore_priv->thread_dead, 0); 136 } 137 138 static void mtd_blktrans_request(struct request_queue *rq) 139 { 140 struct mtd_blktrans_ops *tr = rq->queuedata; 141 wake_up(&tr->blkcore_priv->thread_wq); 142 } 143 144 145 static int blktrans_open(struct inode *i, struct file *f) 146 { 147 struct mtd_blktrans_dev *dev; 148 struct mtd_blktrans_ops *tr; 149 int ret = -ENODEV; 150 151 dev = i->i_bdev->bd_disk->private_data; 152 tr = dev->tr; 153 154 if (!try_module_get(dev->mtd->owner)) 155 goto out; 156 157 if (!try_module_get(tr->owner)) 158 goto out_tr; 159 160 /* FIXME: Locking. A hot pluggable device can go away 161 (del_mtd_device can be called for it) without its module 162 being unloaded. */ 163 dev->mtd->usecount++; 164 165 ret = 0; 166 if (tr->open && (ret = tr->open(dev))) { 167 dev->mtd->usecount--; 168 module_put(dev->mtd->owner); 169 out_tr: 170 module_put(tr->owner); 171 } 172 out: 173 return ret; 174 } 175 176 static int blktrans_release(struct inode *i, struct file *f) 177 { 178 struct mtd_blktrans_dev *dev; 179 struct mtd_blktrans_ops *tr; 180 int ret = 0; 181 182 dev = i->i_bdev->bd_disk->private_data; 183 tr = dev->tr; 184 185 if (tr->release) 186 ret = tr->release(dev); 187 188 if (!ret) { 189 dev->mtd->usecount--; 190 module_put(dev->mtd->owner); 191 module_put(tr->owner); 192 } 193 194 return ret; 195 } 196 197 static int blktrans_getgeo(struct block_device *bdev, struct hd_geometry *geo) 198 { 199 struct mtd_blktrans_dev *dev = bdev->bd_disk->private_data; 200 201 if (dev->tr->getgeo) 202 return dev->tr->getgeo(dev, geo); 203 return -ENOTTY; 204 } 205 206 static int blktrans_ioctl(struct inode *inode, struct file *file, 207 unsigned int cmd, unsigned long arg) 208 { 209 struct mtd_blktrans_dev *dev = inode->i_bdev->bd_disk->private_data; 210 struct mtd_blktrans_ops *tr = dev->tr; 211 212 switch (cmd) { 213 case BLKFLSBUF: 214 if (tr->flush) 215 return tr->flush(dev); 216 /* The core code did the work, we had nothing to do. */ 217 return 0; 218 default: 219 return -ENOTTY; 220 } 221 } 222 223 struct block_device_operations mtd_blktrans_ops = { 224 .owner = THIS_MODULE, 225 .open = blktrans_open, 226 .release = blktrans_release, 227 .ioctl = blktrans_ioctl, 228 .getgeo = blktrans_getgeo, 229 }; 230 231 int add_mtd_blktrans_dev(struct mtd_blktrans_dev *new) 232 { 233 struct mtd_blktrans_ops *tr = new->tr; 234 struct list_head *this; 235 int last_devnum = -1; 236 struct gendisk *gd; 237 238 if (!down_trylock(&mtd_table_mutex)) { 239 up(&mtd_table_mutex); 240 BUG(); 241 } 242 243 list_for_each(this, &tr->devs) { 244 struct mtd_blktrans_dev *d = list_entry(this, struct mtd_blktrans_dev, list); 245 if (new->devnum == -1) { 246 /* Use first free number */ 247 if (d->devnum != last_devnum+1) { 248 /* Found a free devnum. Plug it in here */ 249 new->devnum = last_devnum+1; 250 list_add_tail(&new->list, &d->list); 251 goto added; 252 } 253 } else if (d->devnum == new->devnum) { 254 /* Required number taken */ 255 return -EBUSY; 256 } else if (d->devnum > new->devnum) { 257 /* Required number was free */ 258 list_add_tail(&new->list, &d->list); 259 goto added; 260 } 261 last_devnum = d->devnum; 262 } 263 if (new->devnum == -1) 264 new->devnum = last_devnum+1; 265 266 if ((new->devnum << tr->part_bits) > 256) { 267 return -EBUSY; 268 } 269 270 init_MUTEX(&new->sem); 271 list_add_tail(&new->list, &tr->devs); 272 added: 273 if (!tr->writesect) 274 new->readonly = 1; 275 276 gd = alloc_disk(1 << tr->part_bits); 277 if (!gd) { 278 list_del(&new->list); 279 return -ENOMEM; 280 } 281 gd->major = tr->major; 282 gd->first_minor = (new->devnum) << tr->part_bits; 283 gd->fops = &mtd_blktrans_ops; 284 285 if (tr->part_bits) 286 if (new->devnum < 26) 287 snprintf(gd->disk_name, sizeof(gd->disk_name), 288 "%s%c", tr->name, 'a' + new->devnum); 289 else 290 snprintf(gd->disk_name, sizeof(gd->disk_name), 291 "%s%c%c", tr->name, 292 'a' - 1 + new->devnum / 26, 293 'a' + new->devnum % 26); 294 else 295 snprintf(gd->disk_name, sizeof(gd->disk_name), 296 "%s%d", tr->name, 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 INIT_LIST_HEAD(&tr->devs); 415 list_add(&tr->list, &blktrans_majors); 416 417 for (i=0; i<MAX_MTD_DEVICES; i++) { 418 if (mtd_table[i] && mtd_table[i]->type != MTD_ABSENT) 419 tr->add_mtd(tr, mtd_table[i]); 420 } 421 422 up(&mtd_table_mutex); 423 424 return 0; 425 } 426 427 int deregister_mtd_blktrans(struct mtd_blktrans_ops *tr) 428 { 429 struct list_head *this, *next; 430 431 down(&mtd_table_mutex); 432 433 /* Clean up the kernel thread */ 434 tr->blkcore_priv->exiting = 1; 435 wake_up(&tr->blkcore_priv->thread_wq); 436 wait_for_completion(&tr->blkcore_priv->thread_dead); 437 438 /* Remove it from the list of active majors */ 439 list_del(&tr->list); 440 441 list_for_each_safe(this, next, &tr->devs) { 442 struct mtd_blktrans_dev *dev = list_entry(this, struct mtd_blktrans_dev, list); 443 tr->remove_dev(dev); 444 } 445 446 blk_cleanup_queue(tr->blkcore_priv->rq); 447 unregister_blkdev(tr->major, tr->name); 448 449 up(&mtd_table_mutex); 450 451 kfree(tr->blkcore_priv); 452 453 if (!list_empty(&tr->devs)) 454 BUG(); 455 return 0; 456 } 457 458 static void __exit mtd_blktrans_exit(void) 459 { 460 /* No race here -- if someone's currently in register_mtd_blktrans 461 we're screwed anyway. */ 462 if (blktrans_notifier.list.next) 463 unregister_mtd_user(&blktrans_notifier); 464 } 465 466 module_exit(mtd_blktrans_exit); 467 468 EXPORT_SYMBOL_GPL(register_mtd_blktrans); 469 EXPORT_SYMBOL_GPL(deregister_mtd_blktrans); 470 EXPORT_SYMBOL_GPL(add_mtd_blktrans_dev); 471 EXPORT_SYMBOL_GPL(del_mtd_blktrans_dev); 472 473 MODULE_AUTHOR("David Woodhouse <dwmw2@infradead.org>"); 474 MODULE_LICENSE("GPL"); 475 MODULE_DESCRIPTION("Common interface to block layer for MTD 'translation layers'"); 476