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