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/freezer.h> 20 #include <linux/spinlock.h> 21 #include <linux/hdreg.h> 22 #include <linux/init.h> 23 #include <linux/mutex.h> 24 #include <linux/kthread.h> 25 #include <asm/uaccess.h> 26 27 #include "mtdcore.h" 28 29 static LIST_HEAD(blktrans_majors); 30 31 struct mtd_blkcore_priv { 32 struct task_struct *thread; 33 struct request_queue *rq; 34 spinlock_t queue_lock; 35 }; 36 37 static int do_blktrans_request(struct mtd_blktrans_ops *tr, 38 struct mtd_blktrans_dev *dev, 39 struct request *req) 40 { 41 unsigned long block, nsect; 42 char *buf; 43 44 block = req->sector << 9 >> tr->blkshift; 45 nsect = req->current_nr_sectors << 9 >> tr->blkshift; 46 47 buf = req->buffer; 48 49 if (!blk_fs_request(req)) 50 return 0; 51 52 if (req->sector + req->current_nr_sectors > 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 += tr->blksize) 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 += tr->blksize) 67 if (tr->writesect(dev, block, buf)) 68 return 0; 69 return 1; 70 71 default: 72 printk(KERN_NOTICE "Unknown request %u\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; 84 85 spin_lock_irq(rq->queue_lock); 86 while (!kthread_should_stop()) { 87 struct request *req; 88 struct mtd_blktrans_dev *dev; 89 int res = 0; 90 91 req = elv_next_request(rq); 92 93 if (!req) { 94 set_current_state(TASK_INTERRUPTIBLE); 95 spin_unlock_irq(rq->queue_lock); 96 schedule(); 97 spin_lock_irq(rq->queue_lock); 98 continue; 99 } 100 101 dev = req->rq_disk->private_data; 102 tr = dev->tr; 103 104 spin_unlock_irq(rq->queue_lock); 105 106 mutex_lock(&dev->lock); 107 res = do_blktrans_request(tr, dev, req); 108 mutex_unlock(&dev->lock); 109 110 spin_lock_irq(rq->queue_lock); 111 112 end_request(req, res); 113 } 114 spin_unlock_irq(rq->queue_lock); 115 116 return 0; 117 } 118 119 static void mtd_blktrans_request(struct request_queue *rq) 120 { 121 struct mtd_blktrans_ops *tr = rq->queuedata; 122 wake_up_process(tr->blkcore_priv->thread); 123 } 124 125 126 static int blktrans_open(struct inode *i, struct file *f) 127 { 128 struct mtd_blktrans_dev *dev; 129 struct mtd_blktrans_ops *tr; 130 int ret = -ENODEV; 131 132 dev = i->i_bdev->bd_disk->private_data; 133 tr = dev->tr; 134 135 if (!try_module_get(dev->mtd->owner)) 136 goto out; 137 138 if (!try_module_get(tr->owner)) 139 goto out_tr; 140 141 /* FIXME: Locking. A hot pluggable device can go away 142 (del_mtd_device can be called for it) without its module 143 being unloaded. */ 144 dev->mtd->usecount++; 145 146 ret = 0; 147 if (tr->open && (ret = tr->open(dev))) { 148 dev->mtd->usecount--; 149 module_put(dev->mtd->owner); 150 out_tr: 151 module_put(tr->owner); 152 } 153 out: 154 return ret; 155 } 156 157 static int blktrans_release(struct inode *i, struct file *f) 158 { 159 struct mtd_blktrans_dev *dev; 160 struct mtd_blktrans_ops *tr; 161 int ret = 0; 162 163 dev = i->i_bdev->bd_disk->private_data; 164 tr = dev->tr; 165 166 if (tr->release) 167 ret = tr->release(dev); 168 169 if (!ret) { 170 dev->mtd->usecount--; 171 module_put(dev->mtd->owner); 172 module_put(tr->owner); 173 } 174 175 return ret; 176 } 177 178 static int blktrans_getgeo(struct block_device *bdev, struct hd_geometry *geo) 179 { 180 struct mtd_blktrans_dev *dev = bdev->bd_disk->private_data; 181 182 if (dev->tr->getgeo) 183 return dev->tr->getgeo(dev, geo); 184 return -ENOTTY; 185 } 186 187 static int blktrans_ioctl(struct inode *inode, struct file *file, 188 unsigned int cmd, unsigned long arg) 189 { 190 struct mtd_blktrans_dev *dev = inode->i_bdev->bd_disk->private_data; 191 struct mtd_blktrans_ops *tr = dev->tr; 192 193 switch (cmd) { 194 case BLKFLSBUF: 195 if (tr->flush) 196 return tr->flush(dev); 197 /* The core code did the work, we had nothing to do. */ 198 return 0; 199 default: 200 return -ENOTTY; 201 } 202 } 203 204 static struct block_device_operations mtd_blktrans_ops = { 205 .owner = THIS_MODULE, 206 .open = blktrans_open, 207 .release = blktrans_release, 208 .ioctl = blktrans_ioctl, 209 .getgeo = blktrans_getgeo, 210 }; 211 212 int add_mtd_blktrans_dev(struct mtd_blktrans_dev *new) 213 { 214 struct mtd_blktrans_ops *tr = new->tr; 215 struct list_head *this; 216 int last_devnum = -1; 217 struct gendisk *gd; 218 219 if (mutex_trylock(&mtd_table_mutex)) { 220 mutex_unlock(&mtd_table_mutex); 221 BUG(); 222 } 223 224 list_for_each(this, &tr->devs) { 225 struct mtd_blktrans_dev *d = list_entry(this, struct mtd_blktrans_dev, list); 226 if (new->devnum == -1) { 227 /* Use first free number */ 228 if (d->devnum != last_devnum+1) { 229 /* Found a free devnum. Plug it in here */ 230 new->devnum = last_devnum+1; 231 list_add_tail(&new->list, &d->list); 232 goto added; 233 } 234 } else if (d->devnum == new->devnum) { 235 /* Required number taken */ 236 return -EBUSY; 237 } else if (d->devnum > new->devnum) { 238 /* Required number was free */ 239 list_add_tail(&new->list, &d->list); 240 goto added; 241 } 242 last_devnum = d->devnum; 243 } 244 if (new->devnum == -1) 245 new->devnum = last_devnum+1; 246 247 if ((new->devnum << tr->part_bits) > 256) { 248 return -EBUSY; 249 } 250 251 list_add_tail(&new->list, &tr->devs); 252 added: 253 mutex_init(&new->lock); 254 if (!tr->writesect) 255 new->readonly = 1; 256 257 gd = alloc_disk(1 << tr->part_bits); 258 if (!gd) { 259 list_del(&new->list); 260 return -ENOMEM; 261 } 262 gd->major = tr->major; 263 gd->first_minor = (new->devnum) << tr->part_bits; 264 gd->fops = &mtd_blktrans_ops; 265 266 if (tr->part_bits) 267 if (new->devnum < 26) 268 snprintf(gd->disk_name, sizeof(gd->disk_name), 269 "%s%c", tr->name, 'a' + new->devnum); 270 else 271 snprintf(gd->disk_name, sizeof(gd->disk_name), 272 "%s%c%c", tr->name, 273 'a' - 1 + new->devnum / 26, 274 'a' + new->devnum % 26); 275 else 276 snprintf(gd->disk_name, sizeof(gd->disk_name), 277 "%s%d", tr->name, new->devnum); 278 279 /* 2.5 has capacity in units of 512 bytes while still 280 having BLOCK_SIZE_BITS set to 10. Just to keep us amused. */ 281 set_capacity(gd, (new->size * tr->blksize) >> 9); 282 283 gd->private_data = new; 284 new->blkcore_priv = gd; 285 gd->queue = tr->blkcore_priv->rq; 286 287 if (new->readonly) 288 set_disk_ro(gd, 1); 289 290 add_disk(gd); 291 292 return 0; 293 } 294 295 int del_mtd_blktrans_dev(struct mtd_blktrans_dev *old) 296 { 297 if (mutex_trylock(&mtd_table_mutex)) { 298 mutex_unlock(&mtd_table_mutex); 299 BUG(); 300 } 301 302 list_del(&old->list); 303 304 del_gendisk(old->blkcore_priv); 305 put_disk(old->blkcore_priv); 306 307 return 0; 308 } 309 310 static void blktrans_notify_remove(struct mtd_info *mtd) 311 { 312 struct list_head *this, *this2, *next; 313 314 list_for_each(this, &blktrans_majors) { 315 struct mtd_blktrans_ops *tr = list_entry(this, struct mtd_blktrans_ops, list); 316 317 list_for_each_safe(this2, next, &tr->devs) { 318 struct mtd_blktrans_dev *dev = list_entry(this2, struct mtd_blktrans_dev, list); 319 320 if (dev->mtd == mtd) 321 tr->remove_dev(dev); 322 } 323 } 324 } 325 326 static void blktrans_notify_add(struct mtd_info *mtd) 327 { 328 struct list_head *this; 329 330 if (mtd->type == MTD_ABSENT) 331 return; 332 333 list_for_each(this, &blktrans_majors) { 334 struct mtd_blktrans_ops *tr = list_entry(this, struct mtd_blktrans_ops, list); 335 336 tr->add_mtd(tr, mtd); 337 } 338 339 } 340 341 static struct mtd_notifier blktrans_notifier = { 342 .add = blktrans_notify_add, 343 .remove = blktrans_notify_remove, 344 }; 345 346 int register_mtd_blktrans(struct mtd_blktrans_ops *tr) 347 { 348 int ret, i; 349 350 /* Register the notifier if/when the first device type is 351 registered, to prevent the link/init ordering from fucking 352 us over. */ 353 if (!blktrans_notifier.list.next) 354 register_mtd_user(&blktrans_notifier); 355 356 tr->blkcore_priv = kzalloc(sizeof(*tr->blkcore_priv), GFP_KERNEL); 357 if (!tr->blkcore_priv) 358 return -ENOMEM; 359 360 mutex_lock(&mtd_table_mutex); 361 362 ret = register_blkdev(tr->major, tr->name); 363 if (ret) { 364 printk(KERN_WARNING "Unable to register %s block device on major %d: %d\n", 365 tr->name, tr->major, ret); 366 kfree(tr->blkcore_priv); 367 mutex_unlock(&mtd_table_mutex); 368 return ret; 369 } 370 spin_lock_init(&tr->blkcore_priv->queue_lock); 371 372 tr->blkcore_priv->rq = blk_init_queue(mtd_blktrans_request, &tr->blkcore_priv->queue_lock); 373 if (!tr->blkcore_priv->rq) { 374 unregister_blkdev(tr->major, tr->name); 375 kfree(tr->blkcore_priv); 376 mutex_unlock(&mtd_table_mutex); 377 return -ENOMEM; 378 } 379 380 tr->blkcore_priv->rq->queuedata = tr; 381 blk_queue_hardsect_size(tr->blkcore_priv->rq, tr->blksize); 382 tr->blkshift = ffs(tr->blksize) - 1; 383 384 tr->blkcore_priv->thread = kthread_run(mtd_blktrans_thread, tr, 385 "%sd", tr->name); 386 if (IS_ERR(tr->blkcore_priv->thread)) { 387 blk_cleanup_queue(tr->blkcore_priv->rq); 388 unregister_blkdev(tr->major, tr->name); 389 kfree(tr->blkcore_priv); 390 mutex_unlock(&mtd_table_mutex); 391 return PTR_ERR(tr->blkcore_priv->thread); 392 } 393 394 INIT_LIST_HEAD(&tr->devs); 395 list_add(&tr->list, &blktrans_majors); 396 397 for (i=0; i<MAX_MTD_DEVICES; i++) { 398 if (mtd_table[i] && mtd_table[i]->type != MTD_ABSENT) 399 tr->add_mtd(tr, mtd_table[i]); 400 } 401 402 mutex_unlock(&mtd_table_mutex); 403 404 return 0; 405 } 406 407 int deregister_mtd_blktrans(struct mtd_blktrans_ops *tr) 408 { 409 struct list_head *this, *next; 410 411 mutex_lock(&mtd_table_mutex); 412 413 /* Clean up the kernel thread */ 414 kthread_stop(tr->blkcore_priv->thread); 415 416 /* Remove it from the list of active majors */ 417 list_del(&tr->list); 418 419 list_for_each_safe(this, next, &tr->devs) { 420 struct mtd_blktrans_dev *dev = list_entry(this, struct mtd_blktrans_dev, list); 421 tr->remove_dev(dev); 422 } 423 424 blk_cleanup_queue(tr->blkcore_priv->rq); 425 unregister_blkdev(tr->major, tr->name); 426 427 mutex_unlock(&mtd_table_mutex); 428 429 kfree(tr->blkcore_priv); 430 431 BUG_ON(!list_empty(&tr->devs)); 432 return 0; 433 } 434 435 static void __exit mtd_blktrans_exit(void) 436 { 437 /* No race here -- if someone's currently in register_mtd_blktrans 438 we're screwed anyway. */ 439 if (blktrans_notifier.list.next) 440 unregister_mtd_user(&blktrans_notifier); 441 } 442 443 module_exit(mtd_blktrans_exit); 444 445 EXPORT_SYMBOL_GPL(register_mtd_blktrans); 446 EXPORT_SYMBOL_GPL(deregister_mtd_blktrans); 447 EXPORT_SYMBOL_GPL(add_mtd_blktrans_dev); 448 EXPORT_SYMBOL_GPL(del_mtd_blktrans_dev); 449 450 MODULE_AUTHOR("David Woodhouse <dwmw2@infradead.org>"); 451 MODULE_LICENSE("GPL"); 452 MODULE_DESCRIPTION("Common interface to block layer for MTD 'translation layers'"); 453