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