1 /* 2 * rfd_ftl.c -- resident flash disk (flash translation layer) 3 * 4 * Copyright © 2005 Sean Young <sean@mess.org> 5 * 6 * This type of flash translation layer (FTL) is used by the Embedded BIOS 7 * by General Software. It is known as the Resident Flash Disk (RFD), see: 8 * 9 * http://www.gensw.com/pages/prod/bios/rfd.htm 10 * 11 * based on ftl.c 12 */ 13 14 #include <linux/hdreg.h> 15 #include <linux/init.h> 16 #include <linux/mtd/blktrans.h> 17 #include <linux/mtd/mtd.h> 18 #include <linux/vmalloc.h> 19 #include <linux/slab.h> 20 #include <linux/jiffies.h> 21 #include <linux/module.h> 22 23 #include <asm/types.h> 24 25 static int block_size = 0; 26 module_param(block_size, int, 0); 27 MODULE_PARM_DESC(block_size, "Block size to use by RFD, defaults to erase unit size"); 28 29 #define PREFIX "rfd_ftl: " 30 31 /* This major has been assigned by device@lanana.org */ 32 #ifndef RFD_FTL_MAJOR 33 #define RFD_FTL_MAJOR 256 34 #endif 35 36 /* Maximum number of partitions in an FTL region */ 37 #define PART_BITS 4 38 39 /* An erase unit should start with this value */ 40 #define RFD_MAGIC 0x9193 41 42 /* the second value is 0xffff or 0xffc8; function unknown */ 43 44 /* the third value is always 0xffff, ignored */ 45 46 /* next is an array of mapping for each corresponding sector */ 47 #define HEADER_MAP_OFFSET 3 48 #define SECTOR_DELETED 0x0000 49 #define SECTOR_ZERO 0xfffe 50 #define SECTOR_FREE 0xffff 51 52 #define SECTOR_SIZE 512 53 54 #define SECTORS_PER_TRACK 63 55 56 struct block { 57 enum { 58 BLOCK_OK, 59 BLOCK_ERASING, 60 BLOCK_ERASED, 61 BLOCK_UNUSED, 62 BLOCK_FAILED 63 } state; 64 int free_sectors; 65 int used_sectors; 66 int erases; 67 u_long offset; 68 }; 69 70 struct partition { 71 struct mtd_blktrans_dev mbd; 72 73 u_int block_size; /* size of erase unit */ 74 u_int total_blocks; /* number of erase units */ 75 u_int header_sectors_per_block; /* header sectors in erase unit */ 76 u_int data_sectors_per_block; /* data sectors in erase unit */ 77 u_int sector_count; /* sectors in translated disk */ 78 u_int header_size; /* bytes in header sector */ 79 int reserved_block; /* block next up for reclaim */ 80 int current_block; /* block to write to */ 81 u16 *header_cache; /* cached header */ 82 83 int is_reclaiming; 84 int cylinders; 85 int errors; 86 u_long *sector_map; 87 struct block *blocks; 88 }; 89 90 static int rfd_ftl_writesect(struct mtd_blktrans_dev *dev, u_long sector, char *buf); 91 92 static int build_block_map(struct partition *part, int block_no) 93 { 94 struct block *block = &part->blocks[block_no]; 95 int i; 96 97 block->offset = part->block_size * block_no; 98 99 if (le16_to_cpu(part->header_cache[0]) != RFD_MAGIC) { 100 block->state = BLOCK_UNUSED; 101 return -ENOENT; 102 } 103 104 block->state = BLOCK_OK; 105 106 for (i=0; i<part->data_sectors_per_block; i++) { 107 u16 entry; 108 109 entry = le16_to_cpu(part->header_cache[HEADER_MAP_OFFSET + i]); 110 111 if (entry == SECTOR_DELETED) 112 continue; 113 114 if (entry == SECTOR_FREE) { 115 block->free_sectors++; 116 continue; 117 } 118 119 if (entry == SECTOR_ZERO) 120 entry = 0; 121 122 if (entry >= part->sector_count) { 123 printk(KERN_WARNING PREFIX 124 "'%s': unit #%d: entry %d corrupt, " 125 "sector %d out of range\n", 126 part->mbd.mtd->name, block_no, i, entry); 127 continue; 128 } 129 130 if (part->sector_map[entry] != -1) { 131 printk(KERN_WARNING PREFIX 132 "'%s': more than one entry for sector %d\n", 133 part->mbd.mtd->name, entry); 134 part->errors = 1; 135 continue; 136 } 137 138 part->sector_map[entry] = block->offset + 139 (i + part->header_sectors_per_block) * SECTOR_SIZE; 140 141 block->used_sectors++; 142 } 143 144 if (block->free_sectors == part->data_sectors_per_block) 145 part->reserved_block = block_no; 146 147 return 0; 148 } 149 150 static int scan_header(struct partition *part) 151 { 152 int sectors_per_block; 153 int i, rc = -ENOMEM; 154 int blocks_found; 155 size_t retlen; 156 157 sectors_per_block = part->block_size / SECTOR_SIZE; 158 part->total_blocks = (u32)part->mbd.mtd->size / part->block_size; 159 160 if (part->total_blocks < 2) 161 return -ENOENT; 162 163 /* each erase block has three bytes header, followed by the map */ 164 part->header_sectors_per_block = 165 ((HEADER_MAP_OFFSET + sectors_per_block) * 166 sizeof(u16) + SECTOR_SIZE - 1) / SECTOR_SIZE; 167 168 part->data_sectors_per_block = sectors_per_block - 169 part->header_sectors_per_block; 170 171 part->header_size = (HEADER_MAP_OFFSET + 172 part->data_sectors_per_block) * sizeof(u16); 173 174 part->cylinders = (part->data_sectors_per_block * 175 (part->total_blocks - 1) - 1) / SECTORS_PER_TRACK; 176 177 part->sector_count = part->cylinders * SECTORS_PER_TRACK; 178 179 part->current_block = -1; 180 part->reserved_block = -1; 181 part->is_reclaiming = 0; 182 183 part->header_cache = kmalloc(part->header_size, GFP_KERNEL); 184 if (!part->header_cache) 185 goto err; 186 187 part->blocks = kcalloc(part->total_blocks, sizeof(struct block), 188 GFP_KERNEL); 189 if (!part->blocks) 190 goto err; 191 192 part->sector_map = vmalloc(array_size(sizeof(u_long), 193 part->sector_count)); 194 if (!part->sector_map) { 195 printk(KERN_ERR PREFIX "'%s': unable to allocate memory for " 196 "sector map", part->mbd.mtd->name); 197 goto err; 198 } 199 200 for (i=0; i<part->sector_count; i++) 201 part->sector_map[i] = -1; 202 203 for (i=0, blocks_found=0; i<part->total_blocks; i++) { 204 rc = mtd_read(part->mbd.mtd, i * part->block_size, 205 part->header_size, &retlen, 206 (u_char *)part->header_cache); 207 208 if (!rc && retlen != part->header_size) 209 rc = -EIO; 210 211 if (rc) 212 goto err; 213 214 if (!build_block_map(part, i)) 215 blocks_found++; 216 } 217 218 if (blocks_found == 0) { 219 printk(KERN_NOTICE PREFIX "no RFD magic found in '%s'\n", 220 part->mbd.mtd->name); 221 rc = -ENOENT; 222 goto err; 223 } 224 225 if (part->reserved_block == -1) { 226 printk(KERN_WARNING PREFIX "'%s': no empty erase unit found\n", 227 part->mbd.mtd->name); 228 229 part->errors = 1; 230 } 231 232 return 0; 233 234 err: 235 vfree(part->sector_map); 236 kfree(part->header_cache); 237 kfree(part->blocks); 238 239 return rc; 240 } 241 242 static int rfd_ftl_readsect(struct mtd_blktrans_dev *dev, u_long sector, char *buf) 243 { 244 struct partition *part = (struct partition*)dev; 245 u_long addr; 246 size_t retlen; 247 int rc; 248 249 if (sector >= part->sector_count) 250 return -EIO; 251 252 addr = part->sector_map[sector]; 253 if (addr != -1) { 254 rc = mtd_read(part->mbd.mtd, addr, SECTOR_SIZE, &retlen, 255 (u_char *)buf); 256 if (!rc && retlen != SECTOR_SIZE) 257 rc = -EIO; 258 259 if (rc) { 260 printk(KERN_WARNING PREFIX "error reading '%s' at " 261 "0x%lx\n", part->mbd.mtd->name, addr); 262 return rc; 263 } 264 } else 265 memset(buf, 0, SECTOR_SIZE); 266 267 return 0; 268 } 269 270 static int erase_block(struct partition *part, int block) 271 { 272 struct erase_info *erase; 273 int rc; 274 275 erase = kmalloc(sizeof(struct erase_info), GFP_KERNEL); 276 if (!erase) 277 return -ENOMEM; 278 279 erase->addr = part->blocks[block].offset; 280 erase->len = part->block_size; 281 282 part->blocks[block].state = BLOCK_ERASING; 283 part->blocks[block].free_sectors = 0; 284 285 rc = mtd_erase(part->mbd.mtd, erase); 286 if (rc) { 287 printk(KERN_ERR PREFIX "erase of region %llx,%llx on '%s' " 288 "failed\n", (unsigned long long)erase->addr, 289 (unsigned long long)erase->len, part->mbd.mtd->name); 290 part->blocks[block].state = BLOCK_FAILED; 291 part->blocks[block].free_sectors = 0; 292 part->blocks[block].used_sectors = 0; 293 } else { 294 u16 magic = cpu_to_le16(RFD_MAGIC); 295 size_t retlen; 296 297 part->blocks[block].state = BLOCK_ERASED; 298 part->blocks[block].free_sectors = part->data_sectors_per_block; 299 part->blocks[block].used_sectors = 0; 300 part->blocks[block].erases++; 301 302 rc = mtd_write(part->mbd.mtd, part->blocks[block].offset, 303 sizeof(magic), &retlen, (u_char *)&magic); 304 if (!rc && retlen != sizeof(magic)) 305 rc = -EIO; 306 307 if (rc) { 308 pr_err(PREFIX "'%s': unable to write RFD header at 0x%lx\n", 309 part->mbd.mtd->name, part->blocks[block].offset); 310 part->blocks[block].state = BLOCK_FAILED; 311 } else { 312 part->blocks[block].state = BLOCK_OK; 313 } 314 } 315 316 kfree(erase); 317 318 return rc; 319 } 320 321 static int move_block_contents(struct partition *part, int block_no, u_long *old_sector) 322 { 323 void *sector_data; 324 u16 *map; 325 size_t retlen; 326 int i, rc = -ENOMEM; 327 328 part->is_reclaiming = 1; 329 330 sector_data = kmalloc(SECTOR_SIZE, GFP_KERNEL); 331 if (!sector_data) 332 goto err3; 333 334 map = kmalloc(part->header_size, GFP_KERNEL); 335 if (!map) 336 goto err2; 337 338 rc = mtd_read(part->mbd.mtd, part->blocks[block_no].offset, 339 part->header_size, &retlen, (u_char *)map); 340 341 if (!rc && retlen != part->header_size) 342 rc = -EIO; 343 344 if (rc) { 345 printk(KERN_ERR PREFIX "error reading '%s' at " 346 "0x%lx\n", part->mbd.mtd->name, 347 part->blocks[block_no].offset); 348 349 goto err; 350 } 351 352 for (i=0; i<part->data_sectors_per_block; i++) { 353 u16 entry = le16_to_cpu(map[HEADER_MAP_OFFSET + i]); 354 u_long addr; 355 356 357 if (entry == SECTOR_FREE || entry == SECTOR_DELETED) 358 continue; 359 360 if (entry == SECTOR_ZERO) 361 entry = 0; 362 363 /* already warned about and ignored in build_block_map() */ 364 if (entry >= part->sector_count) 365 continue; 366 367 addr = part->blocks[block_no].offset + 368 (i + part->header_sectors_per_block) * SECTOR_SIZE; 369 370 if (*old_sector == addr) { 371 *old_sector = -1; 372 if (!part->blocks[block_no].used_sectors--) { 373 rc = erase_block(part, block_no); 374 break; 375 } 376 continue; 377 } 378 rc = mtd_read(part->mbd.mtd, addr, SECTOR_SIZE, &retlen, 379 sector_data); 380 381 if (!rc && retlen != SECTOR_SIZE) 382 rc = -EIO; 383 384 if (rc) { 385 printk(KERN_ERR PREFIX "'%s': Unable to " 386 "read sector for relocation\n", 387 part->mbd.mtd->name); 388 389 goto err; 390 } 391 392 rc = rfd_ftl_writesect((struct mtd_blktrans_dev*)part, 393 entry, sector_data); 394 395 if (rc) 396 goto err; 397 } 398 399 err: 400 kfree(map); 401 err2: 402 kfree(sector_data); 403 err3: 404 part->is_reclaiming = 0; 405 406 return rc; 407 } 408 409 static int reclaim_block(struct partition *part, u_long *old_sector) 410 { 411 int block, best_block, score, old_sector_block; 412 int rc; 413 414 /* we have a race if sync doesn't exist */ 415 mtd_sync(part->mbd.mtd); 416 417 score = 0x7fffffff; /* MAX_INT */ 418 best_block = -1; 419 if (*old_sector != -1) 420 old_sector_block = *old_sector / part->block_size; 421 else 422 old_sector_block = -1; 423 424 for (block=0; block<part->total_blocks; block++) { 425 int this_score; 426 427 if (block == part->reserved_block) 428 continue; 429 430 /* 431 * Postpone reclaiming if there is a free sector as 432 * more removed sectors is more efficient (have to move 433 * less). 434 */ 435 if (part->blocks[block].free_sectors) 436 return 0; 437 438 this_score = part->blocks[block].used_sectors; 439 440 if (block == old_sector_block) 441 this_score--; 442 else { 443 /* no point in moving a full block */ 444 if (part->blocks[block].used_sectors == 445 part->data_sectors_per_block) 446 continue; 447 } 448 449 this_score += part->blocks[block].erases; 450 451 if (this_score < score) { 452 best_block = block; 453 score = this_score; 454 } 455 } 456 457 if (best_block == -1) 458 return -ENOSPC; 459 460 part->current_block = -1; 461 part->reserved_block = best_block; 462 463 pr_debug("reclaim_block: reclaiming block #%d with %d used " 464 "%d free sectors\n", best_block, 465 part->blocks[best_block].used_sectors, 466 part->blocks[best_block].free_sectors); 467 468 if (part->blocks[best_block].used_sectors) 469 rc = move_block_contents(part, best_block, old_sector); 470 else 471 rc = erase_block(part, best_block); 472 473 return rc; 474 } 475 476 /* 477 * IMPROVE: It would be best to choose the block with the most deleted sectors, 478 * because if we fill that one up first it'll have the most chance of having 479 * the least live sectors at reclaim. 480 */ 481 static int find_free_block(struct partition *part) 482 { 483 int block, stop; 484 485 block = part->current_block == -1 ? 486 jiffies % part->total_blocks : part->current_block; 487 stop = block; 488 489 do { 490 if (part->blocks[block].free_sectors && 491 block != part->reserved_block) 492 return block; 493 494 if (part->blocks[block].state == BLOCK_UNUSED) 495 erase_block(part, block); 496 497 if (++block >= part->total_blocks) 498 block = 0; 499 500 } while (block != stop); 501 502 return -1; 503 } 504 505 static int find_writable_block(struct partition *part, u_long *old_sector) 506 { 507 int rc, block; 508 size_t retlen; 509 510 block = find_free_block(part); 511 512 if (block == -1) { 513 if (!part->is_reclaiming) { 514 rc = reclaim_block(part, old_sector); 515 if (rc) 516 goto err; 517 518 block = find_free_block(part); 519 } 520 521 if (block == -1) { 522 rc = -ENOSPC; 523 goto err; 524 } 525 } 526 527 rc = mtd_read(part->mbd.mtd, part->blocks[block].offset, 528 part->header_size, &retlen, 529 (u_char *)part->header_cache); 530 531 if (!rc && retlen != part->header_size) 532 rc = -EIO; 533 534 if (rc) { 535 printk(KERN_ERR PREFIX "'%s': unable to read header at " 536 "0x%lx\n", part->mbd.mtd->name, 537 part->blocks[block].offset); 538 goto err; 539 } 540 541 part->current_block = block; 542 543 err: 544 return rc; 545 } 546 547 static int mark_sector_deleted(struct partition *part, u_long old_addr) 548 { 549 int block, offset, rc; 550 u_long addr; 551 size_t retlen; 552 u16 del = cpu_to_le16(SECTOR_DELETED); 553 554 block = old_addr / part->block_size; 555 offset = (old_addr % part->block_size) / SECTOR_SIZE - 556 part->header_sectors_per_block; 557 558 addr = part->blocks[block].offset + 559 (HEADER_MAP_OFFSET + offset) * sizeof(u16); 560 rc = mtd_write(part->mbd.mtd, addr, sizeof(del), &retlen, 561 (u_char *)&del); 562 563 if (!rc && retlen != sizeof(del)) 564 rc = -EIO; 565 566 if (rc) { 567 printk(KERN_ERR PREFIX "error writing '%s' at " 568 "0x%lx\n", part->mbd.mtd->name, addr); 569 goto err; 570 } 571 if (block == part->current_block) 572 part->header_cache[offset + HEADER_MAP_OFFSET] = del; 573 574 part->blocks[block].used_sectors--; 575 576 if (!part->blocks[block].used_sectors && 577 !part->blocks[block].free_sectors) 578 rc = erase_block(part, block); 579 580 err: 581 return rc; 582 } 583 584 static int find_free_sector(const struct partition *part, const struct block *block) 585 { 586 int i, stop; 587 588 i = stop = part->data_sectors_per_block - block->free_sectors; 589 590 do { 591 if (le16_to_cpu(part->header_cache[HEADER_MAP_OFFSET + i]) 592 == SECTOR_FREE) 593 return i; 594 595 if (++i == part->data_sectors_per_block) 596 i = 0; 597 } 598 while(i != stop); 599 600 return -1; 601 } 602 603 static int do_writesect(struct mtd_blktrans_dev *dev, u_long sector, char *buf, ulong *old_addr) 604 { 605 struct partition *part = (struct partition*)dev; 606 struct block *block; 607 u_long addr; 608 int i; 609 int rc; 610 size_t retlen; 611 u16 entry; 612 613 if (part->current_block == -1 || 614 !part->blocks[part->current_block].free_sectors) { 615 616 rc = find_writable_block(part, old_addr); 617 if (rc) 618 goto err; 619 } 620 621 block = &part->blocks[part->current_block]; 622 623 i = find_free_sector(part, block); 624 625 if (i < 0) { 626 rc = -ENOSPC; 627 goto err; 628 } 629 630 addr = (i + part->header_sectors_per_block) * SECTOR_SIZE + 631 block->offset; 632 rc = mtd_write(part->mbd.mtd, addr, SECTOR_SIZE, &retlen, 633 (u_char *)buf); 634 635 if (!rc && retlen != SECTOR_SIZE) 636 rc = -EIO; 637 638 if (rc) { 639 printk(KERN_ERR PREFIX "error writing '%s' at 0x%lx\n", 640 part->mbd.mtd->name, addr); 641 goto err; 642 } 643 644 part->sector_map[sector] = addr; 645 646 entry = cpu_to_le16(sector == 0 ? SECTOR_ZERO : sector); 647 648 part->header_cache[i + HEADER_MAP_OFFSET] = entry; 649 650 addr = block->offset + (HEADER_MAP_OFFSET + i) * sizeof(u16); 651 rc = mtd_write(part->mbd.mtd, addr, sizeof(entry), &retlen, 652 (u_char *)&entry); 653 654 if (!rc && retlen != sizeof(entry)) 655 rc = -EIO; 656 657 if (rc) { 658 printk(KERN_ERR PREFIX "error writing '%s' at 0x%lx\n", 659 part->mbd.mtd->name, addr); 660 goto err; 661 } 662 block->used_sectors++; 663 block->free_sectors--; 664 665 err: 666 return rc; 667 } 668 669 static int rfd_ftl_writesect(struct mtd_blktrans_dev *dev, u_long sector, char *buf) 670 { 671 struct partition *part = (struct partition*)dev; 672 u_long old_addr; 673 int i; 674 int rc = 0; 675 676 pr_debug("rfd_ftl_writesect(sector=0x%lx)\n", sector); 677 678 if (part->reserved_block == -1) { 679 rc = -EACCES; 680 goto err; 681 } 682 683 if (sector >= part->sector_count) { 684 rc = -EIO; 685 goto err; 686 } 687 688 old_addr = part->sector_map[sector]; 689 690 for (i=0; i<SECTOR_SIZE; i++) { 691 if (!buf[i]) 692 continue; 693 694 rc = do_writesect(dev, sector, buf, &old_addr); 695 if (rc) 696 goto err; 697 break; 698 } 699 700 if (i == SECTOR_SIZE) 701 part->sector_map[sector] = -1; 702 703 if (old_addr != -1) 704 rc = mark_sector_deleted(part, old_addr); 705 706 err: 707 return rc; 708 } 709 710 static int rfd_ftl_getgeo(struct mtd_blktrans_dev *dev, struct hd_geometry *geo) 711 { 712 struct partition *part = (struct partition*)dev; 713 714 geo->heads = 1; 715 geo->sectors = SECTORS_PER_TRACK; 716 geo->cylinders = part->cylinders; 717 718 return 0; 719 } 720 721 static void rfd_ftl_add_mtd(struct mtd_blktrans_ops *tr, struct mtd_info *mtd) 722 { 723 struct partition *part; 724 725 if (mtd->type != MTD_NORFLASH || mtd->size > UINT_MAX) 726 return; 727 728 part = kzalloc(sizeof(struct partition), GFP_KERNEL); 729 if (!part) 730 return; 731 732 part->mbd.mtd = mtd; 733 734 if (block_size) 735 part->block_size = block_size; 736 else { 737 if (!mtd->erasesize) { 738 printk(KERN_WARNING PREFIX "please provide block_size"); 739 goto out; 740 } else 741 part->block_size = mtd->erasesize; 742 } 743 744 if (scan_header(part) == 0) { 745 part->mbd.size = part->sector_count; 746 part->mbd.tr = tr; 747 part->mbd.devnum = -1; 748 if (!(mtd->flags & MTD_WRITEABLE)) 749 part->mbd.readonly = 1; 750 else if (part->errors) { 751 printk(KERN_WARNING PREFIX "'%s': errors found, " 752 "setting read-only\n", mtd->name); 753 part->mbd.readonly = 1; 754 } 755 756 printk(KERN_INFO PREFIX "name: '%s' type: %d flags %x\n", 757 mtd->name, mtd->type, mtd->flags); 758 759 if (!add_mtd_blktrans_dev((void*)part)) 760 return; 761 } 762 out: 763 kfree(part); 764 } 765 766 static void rfd_ftl_remove_dev(struct mtd_blktrans_dev *dev) 767 { 768 struct partition *part = (struct partition*)dev; 769 int i; 770 771 for (i=0; i<part->total_blocks; i++) { 772 pr_debug("rfd_ftl_remove_dev:'%s': erase unit #%02d: %d erases\n", 773 part->mbd.mtd->name, i, part->blocks[i].erases); 774 } 775 776 del_mtd_blktrans_dev(dev); 777 vfree(part->sector_map); 778 kfree(part->header_cache); 779 kfree(part->blocks); 780 } 781 782 static struct mtd_blktrans_ops rfd_ftl_tr = { 783 .name = "rfd", 784 .major = RFD_FTL_MAJOR, 785 .part_bits = PART_BITS, 786 .blksize = SECTOR_SIZE, 787 788 .readsect = rfd_ftl_readsect, 789 .writesect = rfd_ftl_writesect, 790 .getgeo = rfd_ftl_getgeo, 791 .add_mtd = rfd_ftl_add_mtd, 792 .remove_dev = rfd_ftl_remove_dev, 793 .owner = THIS_MODULE, 794 }; 795 796 static int __init init_rfd_ftl(void) 797 { 798 return register_mtd_blktrans(&rfd_ftl_tr); 799 } 800 801 static void __exit cleanup_rfd_ftl(void) 802 { 803 deregister_mtd_blktrans(&rfd_ftl_tr); 804 } 805 806 module_init(init_rfd_ftl); 807 module_exit(cleanup_rfd_ftl); 808 809 MODULE_LICENSE("GPL"); 810 MODULE_AUTHOR("Sean Young <sean@mess.org>"); 811 MODULE_DESCRIPTION("Support code for RFD Flash Translation Layer, " 812 "used by General Software's Embedded BIOS"); 813 814