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