drivers/mtd/devices/block2mtd.c

   1 /*
   2  * block2mtd.c - create an mtd from a block device
   3  *
   4  * Copyright (C) 2001,2002      Simon Evans <spse@secret.org.uk>
   5  * Copyright (C) 2004-2006      Joern Engel <joern@wh.fh-wedel.de>
   6  *
   7  * Licence: GPL
   8  */
   9
  10 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
  11
  12 /*
  13  * When the first attempt at device initialization fails, we may need to
  14  * wait a little bit and retry. This timeout, by default 3 seconds, gives
  15  * device time to start up. Required on BCM2708 and a few other chipsets.
  16  */
  17 #define MTD_DEFAULT_TIMEOUT     3
  18
  19 #include <linux/module.h>
  20 #include <linux/delay.h>
  21 #include <linux/fs.h>
  22 #include <linux/blkdev.h>
  23 #include <linux/bio.h>
  24 #include <linux/pagemap.h>
  25 #include <linux/list.h>
  26 #include <linux/init.h>
  27 #include <linux/mtd/mtd.h>
  28 #include <linux/mutex.h>
  29 #include <linux/mount.h>
  30 #include <linux/slab.h>
  31 #include <linux/major.h>
  32
  33 /* Info for the block device */
  34 struct block2mtd_dev {
  35         struct list_head list;
  36         struct block_device *blkdev;
  37         struct mtd_info mtd;
  38         struct mutex write_mutex;
  39 };
  40
  41
  42 /* Static info about the MTD, used in cleanup_module */
  43 static LIST_HEAD(blkmtd_device_list);
  44
  45
  46 static struct page *page_read(struct address_space *mapping, int index)
  47 {
  48         return read_mapping_page(mapping, index, NULL);
  49 }
  50
  51 /* erase a specified part of the device */
  52 static int _block2mtd_erase(struct block2mtd_dev *dev, loff_t to, size_t len)
  53 {
  54         struct address_space *mapping = dev->blkdev->bd_inode->i_mapping;
  55         struct page *page;
  56         int index = to >> PAGE_SHIFT;   // page index
  57         int pages = len >> PAGE_SHIFT;
  58         u_long *p;
  59         u_long *max;
  60
  61         while (pages) {
  62                 page = page_read(mapping, index);
  63                 if (IS_ERR(page))
  64                         return PTR_ERR(page);
  65
  66                 max = page_address(page) + PAGE_SIZE;
  67                 for (p=page_address(page); p<max; p++)
  68                         if (*p != -1UL) {
  69                                 lock_page(page);
  70                                 memset(page_address(page), 0xff, PAGE_SIZE);
  71                                 set_page_dirty(page);
  72                                 unlock_page(page);
  73                                 balance_dirty_pages_ratelimited(mapping);
  74                                 break;
  75                         }
  76
  77                 page_cache_release(page);
  78                 pages--;
  79                 index++;
  80         }
  81         return 0;
  82 }
  83 static int block2mtd_erase(struct mtd_info *mtd, struct erase_info *instr)
  84 {
  85         struct block2mtd_dev *dev = mtd->priv;
  86         size_t from = instr->addr;
  87         size_t len = instr->len;
  88         int err;
  89
  90         instr->state = MTD_ERASING;
  91         mutex_lock(&dev->write_mutex);
  92         err = _block2mtd_erase(dev, from, len);
  93         mutex_unlock(&dev->write_mutex);
  94         if (err) {
  95                 pr_err("erase failed err = %d\n", err);
  96                 instr->state = MTD_ERASE_FAILED;
  97         } else
  98                 instr->state = MTD_ERASE_DONE;
  99
 100         mtd_erase_callback(instr);
 101         return err;
 102 }
 103
 104
 105 static int block2mtd_read(struct mtd_info *mtd, loff_t from, size_t len,
 106                 size_t *retlen, u_char *buf)
 107 {
 108         struct block2mtd_dev *dev = mtd->priv;
 109         struct page *page;
 110         int index = from >> PAGE_SHIFT;
 111         int offset = from & (PAGE_SIZE-1);
 112         int cpylen;
 113
 114         while (len) {
 115                 if ((offset + len) > PAGE_SIZE)
 116                         cpylen = PAGE_SIZE - offset;    // multiple pages
 117                 else
 118                         cpylen = len;   // this page
 119                 len = len - cpylen;
 120
 121                 page = page_read(dev->blkdev->bd_inode->i_mapping, index);
 122                 if (IS_ERR(page))
 123                         return PTR_ERR(page);
 124
 125                 memcpy(buf, page_address(page) + offset, cpylen);
 126                 page_cache_release(page);
 127
 128                 if (retlen)
 129                         *retlen += cpylen;
 130                 buf += cpylen;
 131                 offset = 0;
 132                 index++;
 133         }
 134         return 0;
 135 }
 136
 137
 138 /* write data to the underlying device */
 139 static int _block2mtd_write(struct block2mtd_dev *dev, const u_char *buf,
 140                 loff_t to, size_t len, size_t *retlen)
 141 {
 142         struct page *page;
 143         struct address_space *mapping = dev->blkdev->bd_inode->i_mapping;
 144         int index = to >> PAGE_SHIFT;   // page index
 145         int offset = to & ~PAGE_MASK;   // page offset
 146         int cpylen;
 147
 148         while (len) {
 149                 if ((offset+len) > PAGE_SIZE)
 150                         cpylen = PAGE_SIZE - offset;    // multiple pages
 151                 else
 152                         cpylen = len;                   // this page
 153                 len = len - cpylen;
 154
 155                 page = page_read(mapping, index);
 156                 if (IS_ERR(page))
 157                         return PTR_ERR(page);
 158
 159                 if (memcmp(page_address(page)+offset, buf, cpylen)) {
 160                         lock_page(page);
 161                         memcpy(page_address(page) + offset, buf, cpylen);
 162                         set_page_dirty(page);
 163                         unlock_page(page);
 164                         balance_dirty_pages_ratelimited(mapping);
 165                 }
 166                 page_cache_release(page);
 167
 168                 if (retlen)
 169                         *retlen += cpylen;
 170
 171                 buf += cpylen;
 172                 offset = 0;
 173                 index++;
 174         }
 175         return 0;
 176 }
 177
 178
 179 static int block2mtd_write(struct mtd_info *mtd, loff_t to, size_t len,
 180                 size_t *retlen, const u_char *buf)
 181 {
 182         struct block2mtd_dev *dev = mtd->priv;
 183         int err;
 184
 185         mutex_lock(&dev->write_mutex);
 186         err = _block2mtd_write(dev, buf, to, len, retlen);
 187         mutex_unlock(&dev->write_mutex);
 188         if (err > 0)
 189                 err = 0;
 190         return err;
 191 }
 192
 193
 194 /* sync the device - wait until the write queue is empty */
 195 static void block2mtd_sync(struct mtd_info *mtd)
 196 {
 197         struct block2mtd_dev *dev = mtd->priv;
 198         sync_blockdev(dev->blkdev);
 199         return;
 200 }
 201
 202
 203 static void block2mtd_free_device(struct block2mtd_dev *dev)
 204 {
 205         if (!dev)
 206                 return;
 207
 208         kfree(dev->mtd.name);
 209
 210         if (dev->blkdev) {
 211                 invalidate_mapping_pages(dev->blkdev->bd_inode->i_mapping,
 212                                         0, -1);
 213                 blkdev_put(dev->blkdev, FMODE_READ|FMODE_WRITE|FMODE_EXCL);
 214         }
 215
 216         kfree(dev);
 217 }
 218
 219
 220 static struct block2mtd_dev *add_device(char *devname, int erase_size,
 221                 int timeout)
 222 {
 223 #ifndef MODULE
 224         int i;
 225 #endif
 226         const fmode_t mode = FMODE_READ | FMODE_WRITE | FMODE_EXCL;
 227         struct block_device *bdev = ERR_PTR(-ENODEV);
 228         struct block2mtd_dev *dev;
 229         char *name;
 230
 231         if (!devname)
 232                 return NULL;
 233
 234         dev = kzalloc(sizeof(struct block2mtd_dev), GFP_KERNEL);
 235         if (!dev)
 236                 return NULL;
 237
 238         /* Get a handle on the device */
 239         bdev = blkdev_get_by_path(devname, mode, dev);
 240
 241 #ifndef MODULE
 242         /*
 243          * We might not have the root device mounted at this point.
 244          * Try to resolve the device name by other means.
 245          */
 246         for (i = 0; IS_ERR(bdev) && i <= timeout; i++) {
 247                 dev_t devt;
 248
 249                 if (i)
 250                         /*
 251                          * Calling wait_for_device_probe in the first loop
 252                          * was not enough, sleep for a bit in subsequent
 253                          * go-arounds.
 254                          */
 255                         msleep(1000);
 256                 wait_for_device_probe();
 257
 258                 devt = name_to_dev_t(devname);
 259                 if (!devt)
 260                         continue;
 261                 bdev = blkdev_get_by_dev(devt, mode, dev);
 262         }
 263 #endif
 264
 265         if (IS_ERR(bdev)) {
 266                 pr_err("error: cannot open device %s\n", devname);
 267                 goto err_free_block2mtd;
 268         }
 269         dev->blkdev = bdev;
 270
 271         if (MAJOR(bdev->bd_dev) == MTD_BLOCK_MAJOR) {
 272                 pr_err("attempting to use an MTD device as a block device\n");
 273                 goto err_free_block2mtd;
 274         }
 275
 276         if ((long)dev->blkdev->bd_inode->i_size % erase_size) {
 277                 pr_err("erasesize must be a divisor of device size\n");
 278                 goto err_free_block2mtd;
 279         }
 280
 281         mutex_init(&dev->write_mutex);
 282
 283         /* Setup the MTD structure */
 284         /* make the name contain the block device in */
 285         name = kasprintf(GFP_KERNEL, "block2mtd: %s", devname);
 286         if (!name)
 287                 goto err_destroy_mutex;
 288
 289         dev->mtd.name = name;
 290
 291         dev->mtd.size = dev->blkdev->bd_inode->i_size & PAGE_MASK;
 292         dev->mtd.erasesize = erase_size;
 293         dev->mtd.writesize = 1;
 294         dev->mtd.writebufsize = PAGE_SIZE;
 295         dev->mtd.type = MTD_RAM;
 296         dev->mtd.flags = MTD_CAP_RAM;
 297         dev->mtd._erase = block2mtd_erase;
 298         dev->mtd._write = block2mtd_write;
 299         dev->mtd._sync = block2mtd_sync;
 300         dev->mtd._read = block2mtd_read;
 301         dev->mtd.priv = dev;
 302         dev->mtd.owner = THIS_MODULE;
 303
 304         if (mtd_device_register(&dev->mtd, NULL, 0)) {
 305                 /* Device didn't get added, so free the entry */
 306                 goto err_destroy_mutex;
 307         }
 308
 309         list_add(&dev->list, &blkmtd_device_list);
 310         pr_info("mtd%d: [%s] erase_size = %dKiB [%d]\n",
 311                 dev->mtd.index,
 312                 dev->mtd.name + strlen("block2mtd: "),
 313                 dev->mtd.erasesize >> 10, dev->mtd.erasesize);
 314         return dev;
 315
 316 err_destroy_mutex:
 317         mutex_destroy(&dev->write_mutex);
 318 err_free_block2mtd:
 319         block2mtd_free_device(dev);
 320         return NULL;
 321 }
 322
 323
 324 /* This function works similar to reguler strtoul.  In addition, it
 325  * allows some suffixes for a more human-readable number format:
 326  * ki, Ki, kiB, KiB     - multiply result with 1024
 327  * Mi, MiB              - multiply result with 1024^2
 328  * Gi, GiB              - multiply result with 1024^3
 329  */
 330 static int ustrtoul(const char *cp, char **endp, unsigned int base)
 331 {
 332         unsigned long result = simple_strtoul(cp, endp, base);
 333         switch (**endp) {
 334         case 'G' :
 335                 result *= 1024;
 336         case 'M':
 337                 result *= 1024;
 338         case 'K':
 339         case 'k':
 340                 result *= 1024;
 341         /* By dwmw2 editorial decree, "ki", "Mi" or "Gi" are to be used. */
 342                 if ((*endp)[1] == 'i') {
 343                         if ((*endp)[2] == 'B')
 344                                 (*endp) += 3;
 345                         else
 346                                 (*endp) += 2;
 347                 }
 348         }
 349         return result;
 350 }
 351
 352
 353 static int parse_num(size_t *num, const char *token)
 354 {
 355         char *endp;
 356         size_t n;
 357
 358         n = (size_t) ustrtoul(token, &endp, 0);
 359         if (*endp)
 360                 return -EINVAL;
 361
 362         *num = n;
 363         return 0;
 364 }
 365
 366
 367 static inline void kill_final_newline(char *str)
 368 {
 369         char *newline = strrchr(str, '\n');
 370         if (newline && !newline[1])
 371                 *newline = 0;
 372 }
 373
 374
 375 #ifndef MODULE
 376 static int block2mtd_init_called = 0;
 377 /* 80 for device, 12 for erase size */
 378 static char block2mtd_paramline[80 + 12];
 379 #endif
 380
 381 static int block2mtd_setup2(const char *val)
 382 {
 383         /* 80 for device, 12 for erase size, 80 for name, 8 for timeout */
 384         char buf[80 + 12 + 80 + 8];
 385         char *str = buf;
 386         char *token[2];
 387         char *name;
 388         size_t erase_size = PAGE_SIZE;
 389         unsigned long timeout = MTD_DEFAULT_TIMEOUT;
 390         int i, ret;
 391
 392         if (strnlen(val, sizeof(buf)) >= sizeof(buf)) {
 393                 pr_err("parameter too long\n");
 394                 return 0;
 395         }
 396
 397         strcpy(str, val);
 398         kill_final_newline(str);
 399
 400         for (i = 0; i < 2; i++)
 401                 token[i] = strsep(&str, ",");
 402
 403         if (str) {
 404                 pr_err("too many arguments\n");
 405                 return 0;
 406         }
 407
 408         if (!token[0]) {
 409                 pr_err("no argument\n");
 410                 return 0;
 411         }
 412
 413         name = token[0];
 414         if (strlen(name) + 1 > 80) {
 415                 pr_err("device name too long\n");
 416                 return 0;
 417         }
 418
 419         if (token[1]) {
 420                 ret = parse_num(&erase_size, token[1]);
 421                 if (ret) {
 422                         pr_err("illegal erase size\n");
 423                         return 0;
 424                 }
 425         }
 426
 427         add_device(name, erase_size, timeout);
 428
 429         return 0;
 430 }
 431
 432
 433 static int block2mtd_setup(const char *val, struct kernel_param *kp)
 434 {
 435 #ifdef MODULE
 436         return block2mtd_setup2(val);
 437 #else
 438         /* If more parameters are later passed in via
 439            /sys/module/block2mtd/parameters/block2mtd
 440            and block2mtd_init() has already been called,
 441            we can parse the argument now. */
 442
 443         if (block2mtd_init_called)
 444                 return block2mtd_setup2(val);
 445
 446         /* During early boot stage, we only save the parameters
 447            here. We must parse them later: if the param passed
 448            from kernel boot command line, block2mtd_setup() is
 449            called so early that it is not possible to resolve
 450            the device (even kmalloc() fails). Deter that work to
 451            block2mtd_setup2(). */
 452
 453         strlcpy(block2mtd_paramline, val, sizeof(block2mtd_paramline));
 454
 455         return 0;
 456 #endif
 457 }
 458
 459
 460 module_param_call(block2mtd, block2mtd_setup, NULL, NULL, 0200);
 461 MODULE_PARM_DESC(block2mtd, "Device to use. \"block2mtd=<dev>[,<erasesize>]\"");
 462
 463 static int __init block2mtd_init(void)
 464 {
 465         int ret = 0;
 466
 467 #ifndef MODULE
 468         if (strlen(block2mtd_paramline))
 469                 ret = block2mtd_setup2(block2mtd_paramline);
 470         block2mtd_init_called = 1;
 471 #endif
 472
 473         return ret;
 474 }
 475
 476
 477 static void block2mtd_exit(void)
 478 {
 479         struct list_head *pos, *next;
 480
 481         /* Remove the MTD devices */
 482         list_for_each_safe(pos, next, &blkmtd_device_list) {
 483                 struct block2mtd_dev *dev = list_entry(pos, typeof(*dev), list);
 484                 block2mtd_sync(&dev->mtd);
 485                 mtd_device_unregister(&dev->mtd);
 486                 mutex_destroy(&dev->write_mutex);
 487                 pr_info("mtd%d: [%s] removed\n",
 488                         dev->mtd.index,
 489                         dev->mtd.name + strlen("block2mtd: "));
 490                 list_del(&dev->list);
 491                 block2mtd_free_device(dev);
 492         }
 493 }
 494
 495 late_initcall(block2mtd_init);
 496 module_exit(block2mtd_exit);
 497
 498 MODULE_LICENSE("GPL");
 499 MODULE_AUTHOR("Joern Engel <joern@lazybastard.org>");
 500 MODULE_DESCRIPTION("Emulate an MTD using a block device");