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