1 // SPDX-License-Identifier: GPL-2.0-only 2 /* 3 * rfd_ftl.c -- resident flash disk (flash translation layer) 4 * 5 * Copyright © 2005 Sean Young <sean@mess.org> 6 * 7 * This type of flash translation layer (FTL) is used by the Embedded BIOS 8 * by General Software. It is known as the Resident Flash Disk (RFD), see: 9 * 10 * http://www.gensw.com/pages/prod/bios/rfd.htm 11 * 12 * based on ftl.c 13 */ 14 15 #include <linux/hdreg.h> 16 #include <linux/init.h> 17 #include <linux/mtd/blktrans.h> 18 #include <linux/mtd/mtd.h> 19 #include <linux/vmalloc.h> 20 #include <linux/slab.h> 21 #include <linux/jiffies.h> 22 #include <linux/module.h> 23 24 #include <asm/types.h> 25 26 static int block_size = 0; 27 module_param(block_size, int, 0); 28 MODULE_PARM_DESC(block_size, "Block size to use by RFD, defaults to erase unit size"); 29 30 #define PREFIX "rfd_ftl: " 31 32 /* This major has been assigned by device@lanana.org */ 33 #ifndef RFD_FTL_MAJOR 34 #define RFD_FTL_MAJOR 256 35 #endif 36 37 /* Maximum number of partitions in an FTL region */ 38 #define PART_BITS 4 39 40 /* An erase unit should start with this value */ 41 #define RFD_MAGIC 0x9193 42 43 /* the second value is 0xffff or 0xffc8; function unknown */ 44 45 /* the third value is always 0xffff, ignored */ 46 47 /* next is an array of mapping for each corresponding sector */ 48 #define HEADER_MAP_OFFSET 3 49 #define SECTOR_DELETED 0x0000 50 #define SECTOR_ZERO 0xfffe 51 #define SECTOR_FREE 0xffff 52 53 #define SECTOR_SIZE 512 54 55 #define SECTORS_PER_TRACK 63 56 57 struct block { 58 enum { 59 BLOCK_OK, 60 BLOCK_ERASING, 61 BLOCK_ERASED, 62 BLOCK_UNUSED, 63 BLOCK_FAILED 64 } state; 65 int free_sectors; 66 int used_sectors; 67 int erases; 68 u_long offset; 69 }; 70 71 struct partition { 72 struct mtd_blktrans_dev mbd; 73 74 u_int block_size; /* size of erase unit */ 75 u_int total_blocks; /* number of erase units */ 76 u_int header_sectors_per_block; /* header sectors in erase unit */ 77 u_int data_sectors_per_block; /* data sectors in erase unit */ 78 u_int sector_count; /* sectors in translated disk */ 79 u_int header_size; /* bytes in header sector */ 80 int reserved_block; /* block next up for reclaim */ 81 int current_block; /* block to write to */ 82 u16 *header_cache; /* cached header */ 83 84 int is_reclaiming; 85 int cylinders; 86 int errors; 87 u_long *sector_map; 88 struct block *blocks; 89 }; 90 91 static int rfd_ftl_writesect(struct mtd_blktrans_dev *dev, u_long sector, char *buf); 92 93 static int build_block_map(struct partition *part, int block_no) 94 { 95 struct block *block = &part->blocks[block_no]; 96 int i; 97 98 block->offset = part->block_size * block_no; 99 100 if (le16_to_cpu(part->header_cache[0]) != RFD_MAGIC) { 101 block->state = BLOCK_UNUSED; 102 return -ENOENT; 103 } 104 105 block->state = BLOCK_OK; 106 107 for (i=0; i<part->data_sectors_per_block; i++) { 108 u16 entry; 109 110 entry = le16_to_cpu(part->header_cache[HEADER_MAP_OFFSET + i]); 111 112 if (entry == SECTOR_DELETED) 113 continue; 114 115 if (entry == SECTOR_FREE) { 116 block->free_sectors++; 117 continue; 118 } 119 120 if (entry == SECTOR_ZERO) 121 entry = 0; 122 123 if (entry >= part->sector_count) { 124 printk(KERN_WARNING PREFIX 125 "'%s': unit #%d: entry %d corrupt, " 126 "sector %d out of range\n", 127 part->mbd.mtd->name, block_no, i, entry); 128 continue; 129 } 130 131 if (part->sector_map[entry] != -1) { 132 printk(KERN_WARNING PREFIX 133 "'%s': more than one entry for sector %d\n", 134 part->mbd.mtd->name, entry); 135 part->errors = 1; 136 continue; 137 } 138 139 part->sector_map[entry] = block->offset + 140 (i + part->header_sectors_per_block) * SECTOR_SIZE; 141 142 block->used_sectors++; 143 } 144 145 if (block->free_sectors == part->data_sectors_per_block) 146 part->reserved_block = block_no; 147 148 return 0; 149 } 150 151 static int scan_header(struct partition *part) 152 { 153 int sectors_per_block; 154 int i, rc = -ENOMEM; 155 int blocks_found; 156 size_t retlen; 157 158 sectors_per_block = part->block_size / SECTOR_SIZE; 159 part->total_blocks = (u32)part->mbd.mtd->size / part->block_size; 160 161 if (part->total_blocks < 2) 162 return -ENOENT; 163 164 /* each erase block has three bytes header, followed by the map */ 165 part->header_sectors_per_block = 166 ((HEADER_MAP_OFFSET + sectors_per_block) * 167 sizeof(u16) + SECTOR_SIZE - 1) / SECTOR_SIZE; 168 169 part->data_sectors_per_block = sectors_per_block - 170 part->header_sectors_per_block; 171 172 part->header_size = (HEADER_MAP_OFFSET + 173 part->data_sectors_per_block) * sizeof(u16); 174 175 part->cylinders = (part->data_sectors_per_block * 176 (part->total_blocks - 1) - 1) / SECTORS_PER_TRACK; 177 178 part->sector_count = part->cylinders * SECTORS_PER_TRACK; 179 180 part->current_block = -1; 181 part->reserved_block = -1; 182 part->is_reclaiming = 0; 183 184 part->header_cache = kmalloc(part->header_size, GFP_KERNEL); 185 if (!part->header_cache) 186 goto err; 187 188 part->blocks = kcalloc(part->total_blocks, sizeof(struct block), 189 GFP_KERNEL); 190 if (!part->blocks) 191 goto err; 192 193 part->sector_map = vmalloc(array_size(sizeof(u_long), 194 part->sector_count)); 195 if (!part->sector_map) 196 goto err; 197 198 for (i=0; i<part->sector_count; i++) 199 part->sector_map[i] = -1; 200 201 for (i=0, blocks_found=0; i<part->total_blocks; i++) { 202 rc = mtd_read(part->mbd.mtd, i * part->block_size, 203 part->header_size, &retlen, 204 (u_char *)part->header_cache); 205 206 if (!rc && retlen != part->header_size) 207 rc = -EIO; 208 209 if (rc) 210 goto err; 211 212 if (!build_block_map(part, i)) 213 blocks_found++; 214 } 215 216 if (blocks_found == 0) { 217 printk(KERN_NOTICE PREFIX "no RFD magic found in '%s'\n", 218 part->mbd.mtd->name); 219 rc = -ENOENT; 220 goto err; 221 } 222 223 if (part->reserved_block == -1) { 224 printk(KERN_WARNING PREFIX "'%s': no empty erase unit found\n", 225 part->mbd.mtd->name); 226 227 part->errors = 1; 228 } 229 230 return 0; 231 232 err: 233 vfree(part->sector_map); 234 kfree(part->header_cache); 235 kfree(part->blocks); 236 237 return rc; 238 } 239 240 static int rfd_ftl_readsect(struct mtd_blktrans_dev *dev, u_long sector, char *buf) 241 { 242 struct partition *part = (struct partition*)dev; 243 u_long addr; 244 size_t retlen; 245 int rc; 246 247 if (sector >= part->sector_count) 248 return -EIO; 249 250 addr = part->sector_map[sector]; 251 if (addr != -1) { 252 rc = mtd_read(part->mbd.mtd, addr, SECTOR_SIZE, &retlen, 253 (u_char *)buf); 254 if (!rc && retlen != SECTOR_SIZE) 255 rc = -EIO; 256 257 if (rc) { 258 printk(KERN_WARNING PREFIX "error reading '%s' at " 259 "0x%lx\n", part->mbd.mtd->name, addr); 260 return rc; 261 } 262 } else 263 memset(buf, 0, SECTOR_SIZE); 264 265 return 0; 266 } 267 268 static int erase_block(struct partition *part, int block) 269 { 270 struct erase_info *erase; 271 int rc; 272 273 erase = kmalloc(sizeof(struct erase_info), GFP_KERNEL); 274 if (!erase) 275 return -ENOMEM; 276 277 erase->addr = part->blocks[block].offset; 278 erase->len = part->block_size; 279 280 part->blocks[block].state = BLOCK_ERASING; 281 part->blocks[block].free_sectors = 0; 282 283 rc = mtd_erase(part->mbd.mtd, erase); 284 if (rc) { 285 printk(KERN_ERR PREFIX "erase of region %llx,%llx on '%s' " 286 "failed\n", (unsigned long long)erase->addr, 287 (unsigned long long)erase->len, part->mbd.mtd->name); 288 part->blocks[block].state = BLOCK_FAILED; 289 part->blocks[block].free_sectors = 0; 290 part->blocks[block].used_sectors = 0; 291 } else { 292 u16 magic = cpu_to_le16(RFD_MAGIC); 293 size_t retlen; 294 295 part->blocks[block].state = BLOCK_ERASED; 296 part->blocks[block].free_sectors = part->data_sectors_per_block; 297 part->blocks[block].used_sectors = 0; 298 part->blocks[block].erases++; 299 300 rc = mtd_write(part->mbd.mtd, part->blocks[block].offset, 301 sizeof(magic), &retlen, (u_char *)&magic); 302 if (!rc && retlen != sizeof(magic)) 303 rc = -EIO; 304 305 if (rc) { 306 pr_err(PREFIX "'%s': unable to write RFD header at 0x%lx\n", 307 part->mbd.mtd->name, part->blocks[block].offset); 308 part->blocks[block].state = BLOCK_FAILED; 309 } else { 310 part->blocks[block].state = BLOCK_OK; 311 } 312 } 313 314 kfree(erase); 315 316 return rc; 317 } 318 319 static int move_block_contents(struct partition *part, int block_no, u_long *old_sector) 320 { 321 void *sector_data; 322 u16 *map; 323 size_t retlen; 324 int i, rc = -ENOMEM; 325 326 part->is_reclaiming = 1; 327 328 sector_data = kmalloc(SECTOR_SIZE, GFP_KERNEL); 329 if (!sector_data) 330 goto err3; 331 332 map = kmalloc(part->header_size, GFP_KERNEL); 333 if (!map) 334 goto err2; 335 336 rc = mtd_read(part->mbd.mtd, part->blocks[block_no].offset, 337 part->header_size, &retlen, (u_char *)map); 338 339 if (!rc && retlen != part->header_size) 340 rc = -EIO; 341 342 if (rc) { 343 printk(KERN_ERR PREFIX "error reading '%s' at " 344 "0x%lx\n", part->mbd.mtd->name, 345 part->blocks[block_no].offset); 346 347 goto err; 348 } 349 350 for (i=0; i<part->data_sectors_per_block; i++) { 351 u16 entry = le16_to_cpu(map[HEADER_MAP_OFFSET + i]); 352 u_long addr; 353 354 355 if (entry == SECTOR_FREE || entry == SECTOR_DELETED) 356 continue; 357 358 if (entry == SECTOR_ZERO) 359 entry = 0; 360 361 /* already warned about and ignored in build_block_map() */ 362 if (entry >= part->sector_count) 363 continue; 364 365 addr = part->blocks[block_no].offset + 366 (i + part->header_sectors_per_block) * SECTOR_SIZE; 367 368 if (*old_sector == addr) { 369 *old_sector = -1; 370 if (!part->blocks[block_no].used_sectors--) { 371 rc = erase_block(part, block_no); 372 break; 373 } 374 continue; 375 } 376 rc = mtd_read(part->mbd.mtd, addr, SECTOR_SIZE, &retlen, 377 sector_data); 378 379 if (!rc && retlen != SECTOR_SIZE) 380 rc = -EIO; 381 382 if (rc) { 383 printk(KERN_ERR PREFIX "'%s': Unable to " 384 "read sector for relocation\n", 385 part->mbd.mtd->name); 386 387 goto err; 388 } 389 390 rc = rfd_ftl_writesect((struct mtd_blktrans_dev*)part, 391 entry, sector_data); 392 393 if (rc) 394 goto err; 395 } 396 397 err: 398 kfree(map); 399 err2: 400 kfree(sector_data); 401 err3: 402 part->is_reclaiming = 0; 403 404 return rc; 405 } 406 407 static int reclaim_block(struct partition *part, u_long *old_sector) 408 { 409 int block, best_block, score, old_sector_block; 410 int rc; 411 412 /* we have a race if sync doesn't exist */ 413 mtd_sync(part->mbd.mtd); 414 415 score = 0x7fffffff; /* MAX_INT */ 416 best_block = -1; 417 if (*old_sector != -1) 418 old_sector_block = *old_sector / part->block_size; 419 else 420 old_sector_block = -1; 421 422 for (block=0; block<part->total_blocks; block++) { 423 int this_score; 424 425 if (block == part->reserved_block) 426 continue; 427 428 /* 429 * Postpone reclaiming if there is a free sector as 430 * more removed sectors is more efficient (have to move 431 * less). 432 */ 433 if (part->blocks[block].free_sectors) 434 return 0; 435 436 this_score = part->blocks[block].used_sectors; 437 438 if (block == old_sector_block) 439 this_score--; 440 else { 441 /* no point in moving a full block */ 442 if (part->blocks[block].used_sectors == 443 part->data_sectors_per_block) 444 continue; 445 } 446 447 this_score += part->blocks[block].erases; 448 449 if (this_score < score) { 450 best_block = block; 451 score = this_score; 452 } 453 } 454 455 if (best_block == -1) 456 return -ENOSPC; 457 458 part->current_block = -1; 459 part->reserved_block = best_block; 460 461 pr_debug("reclaim_block: reclaiming block #%d with %d used " 462 "%d free sectors\n", best_block, 463 part->blocks[best_block].used_sectors, 464 part->blocks[best_block].free_sectors); 465 466 if (part->blocks[best_block].used_sectors) 467 rc = move_block_contents(part, best_block, old_sector); 468 else 469 rc = erase_block(part, best_block); 470 471 return rc; 472 } 473 474 /* 475 * IMPROVE: It would be best to choose the block with the most deleted sectors, 476 * because if we fill that one up first it'll have the most chance of having 477 * the least live sectors at reclaim. 478 */ 479 static int find_free_block(struct partition *part) 480 { 481 int block, stop; 482 483 block = part->current_block == -1 ? 484 jiffies % part->total_blocks : part->current_block; 485 stop = block; 486 487 do { 488 if (part->blocks[block].free_sectors && 489 block != part->reserved_block) 490 return block; 491 492 if (part->blocks[block].state == BLOCK_UNUSED) 493 erase_block(part, block); 494 495 if (++block >= part->total_blocks) 496 block = 0; 497 498 } while (block != stop); 499 500 return -1; 501 } 502 503 static int find_writable_block(struct partition *part, u_long *old_sector) 504 { 505 int rc, block; 506 size_t retlen; 507 508 block = find_free_block(part); 509 510 if (block == -1) { 511 if (!part->is_reclaiming) { 512 rc = reclaim_block(part, old_sector); 513 if (rc) 514 goto err; 515 516 block = find_free_block(part); 517 } 518 519 if (block == -1) { 520 rc = -ENOSPC; 521 goto err; 522 } 523 } 524 525 rc = mtd_read(part->mbd.mtd, part->blocks[block].offset, 526 part->header_size, &retlen, 527 (u_char *)part->header_cache); 528 529 if (!rc && retlen != part->header_size) 530 rc = -EIO; 531 532 if (rc) { 533 printk(KERN_ERR PREFIX "'%s': unable to read header at " 534 "0x%lx\n", part->mbd.mtd->name, 535 part->blocks[block].offset); 536 goto err; 537 } 538 539 part->current_block = block; 540 541 err: 542 return rc; 543 } 544 545 static int mark_sector_deleted(struct partition *part, u_long old_addr) 546 { 547 int block, offset, rc; 548 u_long addr; 549 size_t retlen; 550 u16 del = cpu_to_le16(SECTOR_DELETED); 551 552 block = old_addr / part->block_size; 553 offset = (old_addr % part->block_size) / SECTOR_SIZE - 554 part->header_sectors_per_block; 555 556 addr = part->blocks[block].offset + 557 (HEADER_MAP_OFFSET + offset) * sizeof(u16); 558 rc = mtd_write(part->mbd.mtd, addr, sizeof(del), &retlen, 559 (u_char *)&del); 560 561 if (!rc && retlen != sizeof(del)) 562 rc = -EIO; 563 564 if (rc) { 565 printk(KERN_ERR PREFIX "error writing '%s' at " 566 "0x%lx\n", part->mbd.mtd->name, addr); 567 goto err; 568 } 569 if (block == part->current_block) 570 part->header_cache[offset + HEADER_MAP_OFFSET] = del; 571 572 part->blocks[block].used_sectors--; 573 574 if (!part->blocks[block].used_sectors && 575 !part->blocks[block].free_sectors) 576 rc = erase_block(part, block); 577 578 err: 579 return rc; 580 } 581 582 static int find_free_sector(const struct partition *part, const struct block *block) 583 { 584 int i, stop; 585 586 i = stop = part->data_sectors_per_block - block->free_sectors; 587 588 do { 589 if (le16_to_cpu(part->header_cache[HEADER_MAP_OFFSET + i]) 590 == SECTOR_FREE) 591 return i; 592 593 if (++i == part->data_sectors_per_block) 594 i = 0; 595 } 596 while(i != stop); 597 598 return -1; 599 } 600 601 static int do_writesect(struct mtd_blktrans_dev *dev, u_long sector, char *buf, ulong *old_addr) 602 { 603 struct partition *part = (struct partition*)dev; 604 struct block *block; 605 u_long addr; 606 int i; 607 int rc; 608 size_t retlen; 609 u16 entry; 610 611 if (part->current_block == -1 || 612 !part->blocks[part->current_block].free_sectors) { 613 614 rc = find_writable_block(part, old_addr); 615 if (rc) 616 goto err; 617 } 618 619 block = &part->blocks[part->current_block]; 620 621 i = find_free_sector(part, block); 622 623 if (i < 0) { 624 rc = -ENOSPC; 625 goto err; 626 } 627 628 addr = (i + part->header_sectors_per_block) * SECTOR_SIZE + 629 block->offset; 630 rc = mtd_write(part->mbd.mtd, addr, SECTOR_SIZE, &retlen, 631 (u_char *)buf); 632 633 if (!rc && retlen != SECTOR_SIZE) 634 rc = -EIO; 635 636 if (rc) { 637 printk(KERN_ERR PREFIX "error writing '%s' at 0x%lx\n", 638 part->mbd.mtd->name, addr); 639 goto err; 640 } 641 642 part->sector_map[sector] = addr; 643 644 entry = cpu_to_le16(sector == 0 ? SECTOR_ZERO : sector); 645 646 part->header_cache[i + HEADER_MAP_OFFSET] = entry; 647 648 addr = block->offset + (HEADER_MAP_OFFSET + i) * sizeof(u16); 649 rc = mtd_write(part->mbd.mtd, addr, sizeof(entry), &retlen, 650 (u_char *)&entry); 651 652 if (!rc && retlen != sizeof(entry)) 653 rc = -EIO; 654 655 if (rc) { 656 printk(KERN_ERR PREFIX "error writing '%s' at 0x%lx\n", 657 part->mbd.mtd->name, addr); 658 goto err; 659 } 660 block->used_sectors++; 661 block->free_sectors--; 662 663 err: 664 return rc; 665 } 666 667 static int rfd_ftl_writesect(struct mtd_blktrans_dev *dev, u_long sector, char *buf) 668 { 669 struct partition *part = (struct partition*)dev; 670 u_long old_addr; 671 int i; 672 int rc = 0; 673 674 pr_debug("rfd_ftl_writesect(sector=0x%lx)\n", sector); 675 676 if (part->reserved_block == -1) { 677 rc = -EACCES; 678 goto err; 679 } 680 681 if (sector >= part->sector_count) { 682 rc = -EIO; 683 goto err; 684 } 685 686 old_addr = part->sector_map[sector]; 687 688 for (i=0; i<SECTOR_SIZE; i++) { 689 if (!buf[i]) 690 continue; 691 692 rc = do_writesect(dev, sector, buf, &old_addr); 693 if (rc) 694 goto err; 695 break; 696 } 697 698 if (i == SECTOR_SIZE) 699 part->sector_map[sector] = -1; 700 701 if (old_addr != -1) 702 rc = mark_sector_deleted(part, old_addr); 703 704 err: 705 return rc; 706 } 707 708 static int rfd_ftl_getgeo(struct mtd_blktrans_dev *dev, struct hd_geometry *geo) 709 { 710 struct partition *part = (struct partition*)dev; 711 712 geo->heads = 1; 713 geo->sectors = SECTORS_PER_TRACK; 714 geo->cylinders = part->cylinders; 715 716 return 0; 717 } 718 719 static void rfd_ftl_add_mtd(struct mtd_blktrans_ops *tr, struct mtd_info *mtd) 720 { 721 struct partition *part; 722 723 if (mtd->type != MTD_NORFLASH || mtd->size > UINT_MAX) 724 return; 725 726 part = kzalloc(sizeof(struct partition), GFP_KERNEL); 727 if (!part) 728 return; 729 730 part->mbd.mtd = mtd; 731 732 if (block_size) 733 part->block_size = block_size; 734 else { 735 if (!mtd->erasesize) { 736 printk(KERN_WARNING PREFIX "please provide block_size"); 737 goto out; 738 } else 739 part->block_size = mtd->erasesize; 740 } 741 742 if (scan_header(part) == 0) { 743 part->mbd.size = part->sector_count; 744 part->mbd.tr = tr; 745 part->mbd.devnum = -1; 746 if (!(mtd->flags & MTD_WRITEABLE)) 747 part->mbd.readonly = 1; 748 else if (part->errors) { 749 printk(KERN_WARNING PREFIX "'%s': errors found, " 750 "setting read-only\n", mtd->name); 751 part->mbd.readonly = 1; 752 } 753 754 printk(KERN_INFO PREFIX "name: '%s' type: %d flags %x\n", 755 mtd->name, mtd->type, mtd->flags); 756 757 if (!add_mtd_blktrans_dev((void*)part)) 758 return; 759 } 760 out: 761 kfree(part); 762 } 763 764 static void rfd_ftl_remove_dev(struct mtd_blktrans_dev *dev) 765 { 766 struct partition *part = (struct partition*)dev; 767 int i; 768 769 for (i=0; i<part->total_blocks; i++) { 770 pr_debug("rfd_ftl_remove_dev:'%s': erase unit #%02d: %d erases\n", 771 part->mbd.mtd->name, i, part->blocks[i].erases); 772 } 773 774 del_mtd_blktrans_dev(dev); 775 vfree(part->sector_map); 776 kfree(part->header_cache); 777 kfree(part->blocks); 778 } 779 780 static struct mtd_blktrans_ops rfd_ftl_tr = { 781 .name = "rfd", 782 .major = RFD_FTL_MAJOR, 783 .part_bits = PART_BITS, 784 .blksize = SECTOR_SIZE, 785 786 .readsect = rfd_ftl_readsect, 787 .writesect = rfd_ftl_writesect, 788 .getgeo = rfd_ftl_getgeo, 789 .add_mtd = rfd_ftl_add_mtd, 790 .remove_dev = rfd_ftl_remove_dev, 791 .owner = THIS_MODULE, 792 }; 793 794 module_mtd_blktrans(rfd_ftl_tr); 795 796 MODULE_LICENSE("GPL"); 797 MODULE_AUTHOR("Sean Young <sean@mess.org>"); 798 MODULE_DESCRIPTION("Support code for RFD Flash Translation Layer, " 799 "used by General Software's Embedded BIOS"); 800 801