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