drivers/mtd/devices/block2mtd.c

   1 /*
   2  * $Id: block2mtd.c,v 1.30 2005/11/29 14:48:32 gleixner Exp $
   3  *
   4  * block2mtd.c - create an mtd from a block device
   5  *
   6  * Copyright (C) 2001,2002      Simon Evans <spse@secret.org.uk>
   7  * Copyright (C) 2004-2006      Jörn Engel <joern@wh.fh-wedel.de>
   8  *
   9  * Licence: GPL
  10  */
  11 #include <linux/module.h>
  12 #include <linux/fs.h>
  13 #include <linux/blkdev.h>
  14 #include <linux/bio.h>
  15 #include <linux/pagemap.h>
  16 #include <linux/list.h>
  17 #include <linux/init.h>
  18 #include <linux/mtd/mtd.h>
  19 #include <linux/buffer_head.h>
  20 #include <linux/mutex.h>
  21 #include <linux/mount.h>
  22
  23 #define VERSION "$Revision: 1.30 $"
  24
  25
  26 #define ERROR(fmt, args...) printk(KERN_ERR "block2mtd: " fmt "\n" , ## args)
  27 #define INFO(fmt, args...) printk(KERN_INFO "block2mtd: " fmt "\n" , ## args)
  28
  29
  30 /* Info for the block device */
  31 struct block2mtd_dev {
  32         struct list_head list;
  33         struct block_device *blkdev;
  34         struct mtd_info mtd;
  35         struct mutex write_mutex;
  36 };
  37
  38
  39 /* Static info about the MTD, used in cleanup_module */
  40 static LIST_HEAD(blkmtd_device_list);
  41
  42
  43 static struct page* page_read(struct address_space *mapping, int index)
  44 {
  45         filler_t *filler = (filler_t*)mapping->a_ops->readpage;
  46         return read_cache_page(mapping, index, filler, NULL);
  47 }
  48
  49
  50 /* erase a specified part of the device */
  51 static int _block2mtd_erase(struct block2mtd_dev *dev, loff_t to, size_t len)
  52 {
  53         struct address_space *mapping = dev->blkdev->bd_inode->i_mapping;
  54         struct page *page;
  55         int index = to >> PAGE_SHIFT;   // page index
  56         int pages = len >> PAGE_SHIFT;
  57         u_long *p;
  58         u_long *max;
  59
  60         while (pages) {
  61                 page = page_read(mapping, index);
  62                 if (!page)
  63                         return -ENOMEM;
  64                 if (IS_ERR(page))
  65                         return PTR_ERR(page);
  66
  67                 max = page_address(page) + PAGE_SIZE;
  68                 for (p=page_address(page); p<max; p++)
  69                         if (*p != -1UL) {
  70                                 lock_page(page);
  71                                 memset(page_address(page), 0xff, PAGE_SIZE);
  72                                 set_page_dirty(page);
  73                                 unlock_page(page);
  74                                 break;
  75                         }
  76
  77                 page_cache_release(page);
  78                 pages--;
  79                 index++;
  80         }
  81         return 0;
  82 }
  83 static int block2mtd_erase(struct mtd_info *mtd, struct erase_info *instr)
  84 {
  85         struct block2mtd_dev *dev = mtd->priv;
  86         size_t from = instr->addr;
  87         size_t len = instr->len;
  88         int err;
  89
  90         instr->state = MTD_ERASING;
  91         mutex_lock(&dev->write_mutex);
  92         err = _block2mtd_erase(dev, from, len);
  93         mutex_unlock(&dev->write_mutex);
  94         if (err) {
  95                 ERROR("erase failed err = %d", err);
  96                 instr->state = MTD_ERASE_FAILED;
  97         } else
  98                 instr->state = MTD_ERASE_DONE;
  99
 100         instr->state = MTD_ERASE_DONE;
 101         mtd_erase_callback(instr);
 102         return err;
 103 }
 104
 105
 106 static int block2mtd_read(struct mtd_info *mtd, loff_t from, size_t len,
 107                 size_t *retlen, u_char *buf)
 108 {
 109         struct block2mtd_dev *dev = mtd->priv;
 110         struct page *page;
 111         int index = from >> PAGE_SHIFT;
 112         int offset = from & (PAGE_SIZE-1);
 113         int cpylen;
 114
 115         if (from > mtd->size)
 116                 return -EINVAL;
 117         if (from + len > mtd->size)
 118                 len = mtd->size - from;
 119
 120         if (retlen)
 121                 *retlen = 0;
 122
 123         while (len) {
 124                 if ((offset + len) > PAGE_SIZE)
 125                         cpylen = PAGE_SIZE - offset;    // multiple pages
 126                 else
 127                         cpylen = len;   // this page
 128                 len = len - cpylen;
 129
 130                 page = page_read(dev->blkdev->bd_inode->i_mapping, index);
 131                 if (!page)
 132                         return -ENOMEM;
 133                 if (IS_ERR(page))
 134                         return PTR_ERR(page);
 135
 136                 memcpy(buf, page_address(page) + offset, cpylen);
 137                 page_cache_release(page);
 138
 139                 if (retlen)
 140                         *retlen += cpylen;
 141                 buf += cpylen;
 142                 offset = 0;
 143                 index++;
 144         }
 145         return 0;
 146 }
 147
 148
 149 /* write data to the underlying device */
 150 static int _block2mtd_write(struct block2mtd_dev *dev, const u_char *buf,
 151                 loff_t to, size_t len, size_t *retlen)
 152 {
 153         struct page *page;
 154         struct address_space *mapping = dev->blkdev->bd_inode->i_mapping;
 155         int index = to >> PAGE_SHIFT;   // page index
 156         int offset = to & ~PAGE_MASK;   // page offset
 157         int cpylen;
 158
 159         if (retlen)
 160                 *retlen = 0;
 161         while (len) {
 162                 if ((offset+len) > PAGE_SIZE)
 163                         cpylen = PAGE_SIZE - offset;    // multiple pages
 164                 else
 165                         cpylen = len;                   // this page
 166                 len = len - cpylen;
 167
 168                 page = page_read(mapping, index);
 169                 if (!page)
 170                         return -ENOMEM;
 171                 if (IS_ERR(page))
 172                         return PTR_ERR(page);
 173
 174                 if (memcmp(page_address(page)+offset, buf, cpylen)) {
 175                         lock_page(page);
 176                         memcpy(page_address(page) + offset, buf, cpylen);
 177                         set_page_dirty(page);
 178                         unlock_page(page);
 179                 }
 180                 page_cache_release(page);
 181
 182                 if (retlen)
 183                         *retlen += cpylen;
 184
 185                 buf += cpylen;
 186                 offset = 0;
 187                 index++;
 188         }
 189         return 0;
 190 }
 191
 192
 193 static int block2mtd_write(struct mtd_info *mtd, loff_t to, size_t len,
 194                 size_t *retlen, const u_char *buf)
 195 {
 196         struct block2mtd_dev *dev = mtd->priv;
 197         int err;
 198
 199         if (!len)
 200                 return 0;
 201         if (to >= mtd->size)
 202                 return -ENOSPC;
 203         if (to + len > mtd->size)
 204                 len = mtd->size - to;
 205
 206         mutex_lock(&dev->write_mutex);
 207         err = _block2mtd_write(dev, buf, to, len, retlen);
 208         mutex_unlock(&dev->write_mutex);
 209         if (err > 0)
 210                 err = 0;
 211         return err;
 212 }
 213
 214
 215 /* sync the device - wait until the write queue is empty */
 216 static void block2mtd_sync(struct mtd_info *mtd)
 217 {
 218         struct block2mtd_dev *dev = mtd->priv;
 219         sync_blockdev(dev->blkdev);
 220         return;
 221 }
 222
 223
 224 static void block2mtd_free_device(struct block2mtd_dev *dev)
 225 {
 226         if (!dev)
 227                 return;
 228
 229         kfree(dev->mtd.name);
 230
 231         if (dev->blkdev) {
 232                 invalidate_mapping_pages(dev->blkdev->bd_inode->i_mapping,
 233                                         0, -1);
 234                 close_bdev_excl(dev->blkdev);
 235         }
 236
 237         kfree(dev);
 238 }
 239
 240
 241 /* FIXME: ensure that mtd->size % erase_size == 0 */
 242 static struct block2mtd_dev *add_device(char *devname, int erase_size)
 243 {
 244         struct block_device *bdev;
 245         struct block2mtd_dev *dev;
 246
 247         if (!devname)
 248                 return NULL;
 249
 250         dev = kzalloc(sizeof(struct block2mtd_dev), GFP_KERNEL);
 251         if (!dev)
 252                 return NULL;
 253
 254         /* Get a handle on the device */
 255         bdev = open_bdev_excl(devname, O_RDWR, NULL);
 256 #ifndef MODULE
 257         if (IS_ERR(bdev)) {
 258
 259                 /* We might not have rootfs mounted at this point. Try
 260                    to resolve the device name by other means. */
 261
 262                 dev_t devt = name_to_dev_t(devname);
 263                 if (devt) {
 264                         bdev = open_by_devnum(devt, FMODE_WRITE | FMODE_READ);
 265                 }
 266         }
 267 #endif
 268
 269         if (IS_ERR(bdev)) {
 270                 ERROR("error: cannot open device %s", devname);
 271                 goto devinit_err;
 272         }
 273         dev->blkdev = bdev;
 274
 275         if (MAJOR(bdev->bd_dev) == MTD_BLOCK_MAJOR) {
 276                 ERROR("attempting to use an MTD device as a block device");
 277                 goto devinit_err;
 278         }
 279
 280         mutex_init(&dev->write_mutex);
 281
 282         /* Setup the MTD structure */
 283         /* make the name contain the block device in */
 284         dev->mtd.name = kmalloc(sizeof("block2mtd: ") + strlen(devname),
 285                         GFP_KERNEL);
 286         if (!dev->mtd.name)
 287                 goto devinit_err;
 288
 289         sprintf(dev->mtd.name, "block2mtd: %s", devname);
 290
 291         dev->mtd.size = dev->blkdev->bd_inode->i_size & PAGE_MASK;
 292         dev->mtd.erasesize = erase_size;
 293         dev->mtd.writesize = 1;
 294         dev->mtd.type = MTD_RAM;
 295         dev->mtd.flags = MTD_CAP_RAM;
 296         dev->mtd.erase = block2mtd_erase;
 297         dev->mtd.write = block2mtd_write;
 298         dev->mtd.writev = default_mtd_writev;
 299         dev->mtd.sync = block2mtd_sync;
 300         dev->mtd.read = block2mtd_read;
 301         dev->mtd.priv = dev;
 302         dev->mtd.owner = THIS_MODULE;
 303
 304         if (add_mtd_device(&dev->mtd)) {
 305                 /* Device didnt get added, so free the entry */
 306                 goto devinit_err;
 307         }
 308         list_add(&dev->list, &blkmtd_device_list);
 309         INFO("mtd%d: [%s] erase_size = %dKiB [%d]", dev->mtd.index,
 310                         dev->mtd.name + strlen("blkmtd: "),
 311                         dev->mtd.erasesize >> 10, dev->mtd.erasesize);
 312         return dev;
 313
 314 devinit_err:
 315         block2mtd_free_device(dev);
 316         return NULL;
 317 }
 318
 319
 320 /* This function works similar to reguler strtoul.  In addition, it
 321  * allows some suffixes for a more human-readable number format:
 322  * ki, Ki, kiB, KiB     - multiply result with 1024
 323  * Mi, MiB              - multiply result with 1024^2
 324  * Gi, GiB              - multiply result with 1024^3
 325  */
 326 static int ustrtoul(const char *cp, char **endp, unsigned int base)
 327 {
 328         unsigned long result = simple_strtoul(cp, endp, base);
 329         switch (**endp) {
 330         case 'G' :
 331                 result *= 1024;
 332         case 'M':
 333                 result *= 1024;
 334         case 'K':
 335         case 'k':
 336                 result *= 1024;
 337         /* By dwmw2 editorial decree, "ki", "Mi" or "Gi" are to be used. */
 338                 if ((*endp)[1] == 'i') {
 339                         if ((*endp)[2] == 'B')
 340                                 (*endp) += 3;
 341                         else
 342                                 (*endp) += 2;
 343                 }
 344         }
 345         return result;
 346 }
 347
 348
 349 static int parse_num(size_t *num, const char *token)
 350 {
 351         char *endp;
 352         size_t n;
 353
 354         n = (size_t) ustrtoul(token, &endp, 0);
 355         if (*endp)
 356                 return -EINVAL;
 357
 358         *num = n;
 359         return 0;
 360 }
 361
 362
 363 static inline void kill_final_newline(char *str)
 364 {
 365         char *newline = strrchr(str, '\n');
 366         if (newline && !newline[1])
 367                 *newline = 0;
 368 }
 369
 370
 371 #define parse_err(fmt, args...) do {            \
 372         ERROR("block2mtd: " fmt "\n", ## args); \
 373         return 0;                               \
 374 } while (0)
 375
 376 #ifndef MODULE
 377 static int block2mtd_init_called = 0;
 378 static __initdata char block2mtd_paramline[80 + 12]; /* 80 for device, 12 for erase size */
 379 #endif
 380
 381
 382 static int block2mtd_setup2(const char *val)
 383 {
 384         char buf[80 + 12]; /* 80 for device, 12 for erase size */
 385         char *str = buf;
 386         char *token[2];
 387         char *name;
 388         size_t erase_size = PAGE_SIZE;
 389         int i, ret;
 390
 391         if (strnlen(val, sizeof(buf)) >= sizeof(buf))
 392                 parse_err("parameter too long");
 393
 394         strcpy(str, val);
 395         kill_final_newline(str);
 396
 397         for (i = 0; i < 2; i++)
 398                 token[i] = strsep(&str, ",");
 399
 400         if (str)
 401                 parse_err("too many arguments");
 402
 403         if (!token[0])
 404                 parse_err("no argument");
 405
 406         name = token[0];
 407         if (strlen(name) + 1 > 80)
 408                 parse_err("device name too long");
 409
 410         if (token[1]) {
 411                 ret = parse_num(&erase_size, token[1]);
 412                 if (ret) {
 413                         kfree(name);
 414                         parse_err("illegal erase size");
 415                 }
 416         }
 417
 418         add_device(name, erase_size);
 419
 420         return 0;
 421 }
 422
 423
 424 static int block2mtd_setup(const char *val, struct kernel_param *kp)
 425 {
 426 #ifdef MODULE
 427         return block2mtd_setup2(val);
 428 #else
 429         /* If more parameters are later passed in via
 430            /sys/module/block2mtd/parameters/block2mtd
 431            and block2mtd_init() has already been called,
 432            we can parse the argument now. */
 433
 434         if (block2mtd_init_called)
 435                 return block2mtd_setup2(val);
 436
 437         /* During early boot stage, we only save the parameters
 438            here. We must parse them later: if the param passed
 439            from kernel boot command line, block2mtd_setup() is
 440            called so early that it is not possible to resolve
 441            the device (even kmalloc() fails). Deter that work to
 442            block2mtd_setup2(). */
 443
 444         strlcpy(block2mtd_paramline, val, sizeof(block2mtd_paramline));
 445
 446         return 0;
 447 #endif
 448 }
 449
 450
 451 module_param_call(block2mtd, block2mtd_setup, NULL, NULL, 0200);
 452 MODULE_PARM_DESC(block2mtd, "Device to use. \"block2mtd=<dev>[,<erasesize>]\"");
 453
 454 static int __init block2mtd_init(void)
 455 {
 456         int ret = 0;
 457         INFO("version " VERSION);
 458
 459 #ifndef MODULE
 460         if (strlen(block2mtd_paramline))
 461                 ret = block2mtd_setup2(block2mtd_paramline);
 462         block2mtd_init_called = 1;
 463 #endif
 464
 465         return ret;
 466 }
 467
 468
 469 static void __devexit block2mtd_exit(void)
 470 {
 471         struct list_head *pos, *next;
 472
 473         /* Remove the MTD devices */
 474         list_for_each_safe(pos, next, &blkmtd_device_list) {
 475                 struct block2mtd_dev *dev = list_entry(pos, typeof(*dev), list);
 476                 block2mtd_sync(&dev->mtd);
 477                 del_mtd_device(&dev->mtd);
 478                 INFO("mtd%d: [%s] removed", dev->mtd.index,
 479                                 dev->mtd.name + strlen("blkmtd: "));
 480                 list_del(&dev->list);
 481                 block2mtd_free_device(dev);
 482         }
 483 }
 484
 485
 486 module_init(block2mtd_init);
 487 module_exit(block2mtd_exit);
 488
 489 MODULE_LICENSE("GPL");
 490 MODULE_AUTHOR("Simon Evans <spse@secret.org.uk> and others");
 491 MODULE_DESCRIPTION("Emulate an MTD using a block device");