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'"); 479