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 /* Maximum number of comma-separated items in the 'block2mtd=' parameter */
  35 #define BLOCK2MTD_PARAM_MAX_COUNT 3
  36
  37 /* Info for the block device */
  38 struct block2mtd_dev {
  39         struct list_head list;
  40         struct file *bdev_file;
  41         struct mtd_info mtd;
  42         struct mutex write_mutex;
  43 };
  44
  45
  46 /* Static info about the MTD, used in cleanup_module */
  47 static LIST_HEAD(blkmtd_device_list);
  48
  49
  50 static struct page *page_read(struct address_space *mapping, pgoff_t index)
  51 {
  52         return read_mapping_page(mapping, index, NULL);
  53 }
  54
  55 /* erase a specified part of the device */
  56 static int _block2mtd_erase(struct block2mtd_dev *dev, loff_t to, size_t len)
  57 {
  58         struct address_space *mapping = dev->bdev_file->f_mapping;
  59         struct page *page;
  60         pgoff_t index = to >> PAGE_SHIFT;       // page index
  61         int pages = len >> PAGE_SHIFT;
  62         u_long *p;
  63         u_long *max;
  64
  65         while (pages) {
  66                 page = page_read(mapping, index);
  67                 if (IS_ERR(page))
  68                         return PTR_ERR(page);
  69
  70                 max = page_address(page) + PAGE_SIZE;
  71                 for (p=page_address(page); p<max; p++)
  72                         if (*p != -1UL) {
  73                                 lock_page(page);
  74                                 memset(page_address(page), 0xff, PAGE_SIZE);
  75                                 set_page_dirty(page);
  76                                 unlock_page(page);
  77                                 balance_dirty_pages_ratelimited(mapping);
  78                                 break;
  79                         }
  80
  81                 put_page(page);
  82                 pages--;
  83                 index++;
  84         }
  85         return 0;
  86 }
  87 static int block2mtd_erase(struct mtd_info *mtd, struct erase_info *instr)
  88 {
  89         struct block2mtd_dev *dev = mtd->priv;
  90         size_t from = instr->addr;
  91         size_t len = instr->len;
  92         int err;
  93
  94         mutex_lock(&dev->write_mutex);
  95         err = _block2mtd_erase(dev, from, len);
  96         mutex_unlock(&dev->write_mutex);
  97         if (err)
  98                 pr_err("erase failed err = %d\n", err);
  99
 100         return err;
 101 }
 102
 103
 104 static int block2mtd_read(struct mtd_info *mtd, loff_t from, size_t len,
 105                 size_t *retlen, u_char *buf)
 106 {
 107         struct block2mtd_dev *dev = mtd->priv;
 108         struct address_space *mapping = dev->bdev_file->f_mapping;
 109         struct page *page;
 110         pgoff_t 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(mapping, index);
 122                 if (IS_ERR(page))
 123                         return PTR_ERR(page);
 124
 125                 memcpy(buf, page_address(page) + offset, cpylen);
 126                 put_page(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->bdev_file->f_mapping;
 144         pgoff_t 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                 put_page(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(file_bdev(dev->bdev_file));
 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->bdev_file) {
 211                 invalidate_mapping_pages(dev->bdev_file->f_mapping, 0, -1);
 212                 bdev_fput(dev->bdev_file);
 213         }
 214
 215         kfree(dev);
 216 }
 217
 218 /*
 219  * This function is marked __ref because it calls the __init marked
 220  * early_lookup_bdev when called from the early boot code.
 221  */
 222 static struct file __ref *mdtblock_early_get_bdev(const char *devname,
 223                 blk_mode_t mode, int timeout, struct block2mtd_dev *dev)
 224 {
 225         struct file *bdev_file = ERR_PTR(-ENODEV);
 226 #ifndef MODULE
 227         int i;
 228
 229         /*
 230          * We can't use early_lookup_bdev from a running system.
 231          */
 232         if (system_state >= SYSTEM_RUNNING)
 233                 return bdev_file;
 234
 235         /*
 236          * We might not have the root device mounted at this point.
 237          * Try to resolve the device name by other means.
 238          */
 239         for (i = 0; i <= timeout; i++) {
 240                 dev_t devt;
 241
 242                 if (i)
 243                         /*
 244                          * Calling wait_for_device_probe in the first loop
 245                          * was not enough, sleep for a bit in subsequent
 246                          * go-arounds.
 247                          */
 248                         msleep(1000);
 249                 wait_for_device_probe();
 250
 251                 if (!early_lookup_bdev(devname, &devt)) {
 252                         bdev_file = bdev_file_open_by_dev(devt, mode, dev, NULL);
 253                         if (!IS_ERR(bdev_file))
 254                                 break;
 255                 }
 256         }
 257 #endif
 258         return bdev_file;
 259 }
 260
 261 static struct block2mtd_dev *add_device(char *devname, int erase_size,
 262                 char *label, int timeout)
 263 {
 264         const blk_mode_t mode = BLK_OPEN_READ | BLK_OPEN_WRITE;
 265         struct file *bdev_file;
 266         struct block_device *bdev;
 267         struct block2mtd_dev *dev;
 268         loff_t size;
 269         char *name;
 270
 271         if (!devname)
 272                 return NULL;
 273
 274         dev = kzalloc(sizeof(struct block2mtd_dev), GFP_KERNEL);
 275         if (!dev)
 276                 return NULL;
 277
 278         /* Get a handle on the device */
 279         bdev_file = bdev_file_open_by_path(devname, mode, dev, NULL);
 280         if (IS_ERR(bdev_file))
 281                 bdev_file = mdtblock_early_get_bdev(devname, mode, timeout,
 282                                                       dev);
 283         if (IS_ERR(bdev_file)) {
 284                 pr_err("error: cannot open device %s\n", devname);
 285                 goto err_free_block2mtd;
 286         }
 287         dev->bdev_file = bdev_file;
 288         bdev = file_bdev(bdev_file);
 289
 290         if (MAJOR(bdev->bd_dev) == MTD_BLOCK_MAJOR) {
 291                 pr_err("attempting to use an MTD device as a block device\n");
 292                 goto err_free_block2mtd;
 293         }
 294
 295         size = bdev_nr_bytes(bdev);
 296         if ((long)size % erase_size) {
 297                 pr_err("erasesize must be a divisor of device size\n");
 298                 goto err_free_block2mtd;
 299         }
 300
 301         mutex_init(&dev->write_mutex);
 302
 303         /* Setup the MTD structure */
 304         /* make the name contain the block device in */
 305         if (!label)
 306                 name = kasprintf(GFP_KERNEL, "block2mtd: %s", devname);
 307         else
 308                 name = kstrdup(label, GFP_KERNEL);
 309         if (!name)
 310                 goto err_destroy_mutex;
 311
 312         dev->mtd.name = name;
 313
 314         dev->mtd.size = size & PAGE_MASK;
 315         dev->mtd.erasesize = erase_size;
 316         dev->mtd.writesize = 1;
 317         dev->mtd.writebufsize = PAGE_SIZE;
 318         dev->mtd.type = MTD_RAM;
 319         dev->mtd.flags = MTD_CAP_RAM;
 320         dev->mtd._erase = block2mtd_erase;
 321         dev->mtd._write = block2mtd_write;
 322         dev->mtd._sync = block2mtd_sync;
 323         dev->mtd._read = block2mtd_read;
 324         dev->mtd.priv = dev;
 325         dev->mtd.owner = THIS_MODULE;
 326
 327         if (mtd_device_register(&dev->mtd, NULL, 0)) {
 328                 /* Device didn't get added, so free the entry */
 329                 goto err_destroy_mutex;
 330         }
 331
 332         list_add(&dev->list, &blkmtd_device_list);
 333         pr_info("mtd%d: [%s] erase_size = %dKiB [%d]\n",
 334                 dev->mtd.index,
 335                 label ? label : dev->mtd.name + strlen("block2mtd: "),
 336                 dev->mtd.erasesize >> 10, dev->mtd.erasesize);
 337         return dev;
 338
 339 err_destroy_mutex:
 340         mutex_destroy(&dev->write_mutex);
 341 err_free_block2mtd:
 342         block2mtd_free_device(dev);
 343         return NULL;
 344 }
 345
 346
 347 /* This function works similar to reguler strtoul.  In addition, it
 348  * allows some suffixes for a more human-readable number format:
 349  * ki, Ki, kiB, KiB     - multiply result with 1024
 350  * Mi, MiB              - multiply result with 1024^2
 351  * Gi, GiB              - multiply result with 1024^3
 352  */
 353 static int ustrtoul(const char *cp, char **endp, unsigned int base)
 354 {
 355         unsigned long result = simple_strtoul(cp, endp, base);
 356         switch (**endp) {
 357         case 'G' :
 358                 result *= 1024;
 359                 fallthrough;
 360         case 'M':
 361                 result *= 1024;
 362                 fallthrough;
 363         case 'K':
 364         case 'k':
 365                 result *= 1024;
 366         /* By dwmw2 editorial decree, "ki", "Mi" or "Gi" are to be used. */
 367                 if ((*endp)[1] == 'i') {
 368                         if ((*endp)[2] == 'B')
 369                                 (*endp) += 3;
 370                         else
 371                                 (*endp) += 2;
 372                 }
 373         }
 374         return result;
 375 }
 376
 377
 378 static int parse_num(size_t *num, const char *token)
 379 {
 380         char *endp;
 381         size_t n;
 382
 383         n = (size_t) ustrtoul(token, &endp, 0);
 384         if (*endp)
 385                 return -EINVAL;
 386
 387         *num = n;
 388         return 0;
 389 }
 390
 391
 392 static inline void kill_final_newline(char *str)
 393 {
 394         char *newline = strrchr(str, '\n');
 395         if (newline && !newline[1])
 396                 *newline = 0;
 397 }
 398
 399
 400 #ifndef MODULE
 401 static int block2mtd_init_called = 0;
 402 /* 80 for device, 12 for erase size */
 403 static char block2mtd_paramline[80 + 12];
 404 #endif
 405
 406 static int block2mtd_setup2(const char *val)
 407 {
 408         /* 80 for device, 12 for erase size, 80 for name, 8 for timeout */
 409         char buf[80 + 12 + 80 + 8];
 410         char *str = buf;
 411         char *token[BLOCK2MTD_PARAM_MAX_COUNT];
 412         char *name;
 413         char *label = NULL;
 414         size_t erase_size = PAGE_SIZE;
 415         unsigned long timeout = MTD_DEFAULT_TIMEOUT;
 416         int i, ret;
 417
 418         if (strnlen(val, sizeof(buf)) >= sizeof(buf)) {
 419                 pr_err("parameter too long\n");
 420                 return 0;
 421         }
 422
 423         strcpy(str, val);
 424         kill_final_newline(str);
 425
 426         for (i = 0; i < BLOCK2MTD_PARAM_MAX_COUNT; i++)
 427                 token[i] = strsep(&str, ",");
 428
 429         if (str) {
 430                 pr_err("too many arguments\n");
 431                 return 0;
 432         }
 433
 434         if (!token[0]) {
 435                 pr_err("no argument\n");
 436                 return 0;
 437         }
 438
 439         name = token[0];
 440         if (strlen(name) + 1 > 80) {
 441                 pr_err("device name too long\n");
 442                 return 0;
 443         }
 444
 445         /* Optional argument when custom label is used */
 446         if (token[1] && strlen(token[1])) {
 447                 ret = parse_num(&erase_size, token[1]);
 448                 if (ret) {
 449                         pr_err("illegal erase size\n");
 450                         return 0;
 451                 }
 452         }
 453
 454         if (token[2]) {
 455                 label = token[2];
 456                 pr_info("Using custom MTD label '%s' for dev %s\n", label, name);
 457         }
 458
 459         add_device(name, erase_size, label, timeout);
 460
 461         return 0;
 462 }
 463
 464
 465 static int block2mtd_setup(const char *val, const struct kernel_param *kp)
 466 {
 467 #ifdef MODULE
 468         return block2mtd_setup2(val);
 469 #else
 470         /* If more parameters are later passed in via
 471            /sys/module/block2mtd/parameters/block2mtd
 472            and block2mtd_init() has already been called,
 473            we can parse the argument now. */
 474
 475         if (block2mtd_init_called)
 476                 return block2mtd_setup2(val);
 477
 478         /* During early boot stage, we only save the parameters
 479            here. We must parse them later: if the param passed
 480            from kernel boot command line, block2mtd_setup() is
 481            called so early that it is not possible to resolve
 482            the device (even kmalloc() fails). Deter that work to
 483            block2mtd_setup2(). */
 484
 485         strscpy(block2mtd_paramline, val, sizeof(block2mtd_paramline));
 486
 487         return 0;
 488 #endif
 489 }
 490
 491
 492 module_param_call(block2mtd, block2mtd_setup, NULL, NULL, 0200);
 493 MODULE_PARM_DESC(block2mtd, "Device to use. \"block2mtd=<dev>[,[<erasesize>][,<label>]]\"");
 494
 495 static int __init block2mtd_init(void)
 496 {
 497         int ret = 0;
 498
 499 #ifndef MODULE
 500         if (strlen(block2mtd_paramline))
 501                 ret = block2mtd_setup2(block2mtd_paramline);
 502         block2mtd_init_called = 1;
 503 #endif
 504
 505         return ret;
 506 }
 507
 508
 509 static void block2mtd_exit(void)
 510 {
 511         struct list_head *pos, *next;
 512
 513         /* Remove the MTD devices */
 514         list_for_each_safe(pos, next, &blkmtd_device_list) {
 515                 struct block2mtd_dev *dev = list_entry(pos, typeof(*dev), list);
 516                 block2mtd_sync(&dev->mtd);
 517                 mtd_device_unregister(&dev->mtd);
 518                 mutex_destroy(&dev->write_mutex);
 519                 pr_info("mtd%d: [%s] removed\n",
 520                         dev->mtd.index,
 521                         dev->mtd.name + strlen("block2mtd: "));
 522                 list_del(&dev->list);
 523                 block2mtd_free_device(dev);
 524         }
 525 }
 526
 527 late_initcall(block2mtd_init);
 528 module_exit(block2mtd_exit);
 529
 530 MODULE_LICENSE("GPL");
 531 MODULE_AUTHOR("Joern Engel <joern@lazybastard.org>");
 532 MODULE_DESCRIPTION("Emulate an MTD using a block device");