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