1 /* 2 * Copyright (C) 2006-2008 Nokia Corporation 3 * 4 * This program is free software; you can redistribute it and/or modify it 5 * under the terms of the GNU General Public License version 2 as published by 6 * the Free Software Foundation. 7 * 8 * This program is distributed in the hope that it will be useful, but WITHOUT 9 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or 10 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for 11 * more details. 12 * 13 * You should have received a copy of the GNU General Public License along with 14 * this program; see the file COPYING. If not, write to the Free Software 15 * Foundation, 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA. 16 * 17 * Test OOB read and write on MTD device. 18 * 19 * Author: Adrian Hunter <ext-adrian.hunter@nokia.com> 20 */ 21 22 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt 23 24 #include <asm/div64.h> 25 #include <linux/init.h> 26 #include <linux/module.h> 27 #include <linux/moduleparam.h> 28 #include <linux/err.h> 29 #include <linux/mtd/mtd.h> 30 #include <linux/slab.h> 31 #include <linux/sched.h> 32 #include <linux/random.h> 33 34 #include "mtd_test.h" 35 36 static int dev = -EINVAL; 37 static int bitflip_limit; 38 module_param(dev, int, S_IRUGO); 39 MODULE_PARM_DESC(dev, "MTD device number to use"); 40 module_param(bitflip_limit, int, S_IRUGO); 41 MODULE_PARM_DESC(bitflip_limit, "Max. allowed bitflips per page"); 42 43 static struct mtd_info *mtd; 44 static unsigned char *readbuf; 45 static unsigned char *writebuf; 46 static unsigned char *bbt; 47 48 static int ebcnt; 49 static int pgcnt; 50 static int errcnt; 51 static int use_offset; 52 static int use_len; 53 static int use_len_max; 54 static int vary_offset; 55 static struct rnd_state rnd_state; 56 57 static void do_vary_offset(void) 58 { 59 use_len -= 1; 60 if (use_len < 1) { 61 use_offset += 1; 62 if (use_offset >= use_len_max) 63 use_offset = 0; 64 use_len = use_len_max - use_offset; 65 } 66 } 67 68 static int write_eraseblock(int ebnum) 69 { 70 int i; 71 struct mtd_oob_ops ops; 72 int err = 0; 73 loff_t addr = (loff_t)ebnum * mtd->erasesize; 74 75 prandom_bytes_state(&rnd_state, writebuf, use_len_max * pgcnt); 76 for (i = 0; i < pgcnt; ++i, addr += mtd->writesize) { 77 ops.mode = MTD_OPS_AUTO_OOB; 78 ops.len = 0; 79 ops.retlen = 0; 80 ops.ooblen = use_len; 81 ops.oobretlen = 0; 82 ops.ooboffs = use_offset; 83 ops.datbuf = NULL; 84 ops.oobbuf = writebuf + (use_len_max * i) + use_offset; 85 err = mtd_write_oob(mtd, addr, &ops); 86 if (err || ops.oobretlen != use_len) { 87 pr_err("error: writeoob failed at %#llx\n", 88 (long long)addr); 89 pr_err("error: use_len %d, use_offset %d\n", 90 use_len, use_offset); 91 errcnt += 1; 92 return err ? err : -1; 93 } 94 if (vary_offset) 95 do_vary_offset(); 96 } 97 98 return err; 99 } 100 101 static int write_whole_device(void) 102 { 103 int err; 104 unsigned int i; 105 106 pr_info("writing OOBs of whole device\n"); 107 for (i = 0; i < ebcnt; ++i) { 108 if (bbt[i]) 109 continue; 110 err = write_eraseblock(i); 111 if (err) 112 return err; 113 if (i % 256 == 0) 114 pr_info("written up to eraseblock %u\n", i); 115 116 err = mtdtest_relax(); 117 if (err) 118 return err; 119 } 120 pr_info("written %u eraseblocks\n", i); 121 return 0; 122 } 123 124 /* 125 * Display the address, offset and data bytes at comparison failure. 126 * Return number of bitflips encountered. 127 */ 128 static size_t memcmpshowoffset(loff_t addr, loff_t offset, const void *cs, 129 const void *ct, size_t count) 130 { 131 const unsigned char *su1, *su2; 132 int res; 133 size_t i = 0; 134 size_t bitflips = 0; 135 136 for (su1 = cs, su2 = ct; 0 < count; ++su1, ++su2, count--, i++) { 137 res = *su1 ^ *su2; 138 if (res) { 139 pr_info("error @addr[0x%lx:0x%lx] 0x%x -> 0x%x diff 0x%x\n", 140 (unsigned long)addr, (unsigned long)offset + i, 141 *su1, *su2, res); 142 bitflips += hweight8(res); 143 } 144 } 145 146 return bitflips; 147 } 148 149 #define memcmpshow(addr, cs, ct, count) memcmpshowoffset((addr), 0, (cs), (ct),\ 150 (count)) 151 152 /* 153 * Compare with 0xff and show the address, offset and data bytes at 154 * comparison failure. Return number of bitflips encountered. 155 */ 156 static size_t memffshow(loff_t addr, loff_t offset, const void *cs, 157 size_t count) 158 { 159 const unsigned char *su1; 160 int res; 161 size_t i = 0; 162 size_t bitflips = 0; 163 164 for (su1 = cs; 0 < count; ++su1, count--, i++) { 165 res = *su1 ^ 0xff; 166 if (res) { 167 pr_info("error @addr[0x%lx:0x%lx] 0x%x -> 0xff diff 0x%x\n", 168 (unsigned long)addr, (unsigned long)offset + i, 169 *su1, res); 170 bitflips += hweight8(res); 171 } 172 } 173 174 return bitflips; 175 } 176 177 static int verify_eraseblock(int ebnum) 178 { 179 int i; 180 struct mtd_oob_ops ops; 181 int err = 0; 182 loff_t addr = (loff_t)ebnum * mtd->erasesize; 183 size_t bitflips; 184 185 prandom_bytes_state(&rnd_state, writebuf, use_len_max * pgcnt); 186 for (i = 0; i < pgcnt; ++i, addr += mtd->writesize) { 187 ops.mode = MTD_OPS_AUTO_OOB; 188 ops.len = 0; 189 ops.retlen = 0; 190 ops.ooblen = use_len; 191 ops.oobretlen = 0; 192 ops.ooboffs = use_offset; 193 ops.datbuf = NULL; 194 ops.oobbuf = readbuf; 195 err = mtd_read_oob(mtd, addr, &ops); 196 if (mtd_is_bitflip(err)) 197 err = 0; 198 199 if (err || ops.oobretlen != use_len) { 200 pr_err("error: readoob failed at %#llx\n", 201 (long long)addr); 202 errcnt += 1; 203 return err ? err : -1; 204 } 205 206 bitflips = memcmpshow(addr, readbuf, 207 writebuf + (use_len_max * i) + use_offset, 208 use_len); 209 if (bitflips > bitflip_limit) { 210 pr_err("error: verify failed at %#llx\n", 211 (long long)addr); 212 errcnt += 1; 213 if (errcnt > 1000) { 214 pr_err("error: too many errors\n"); 215 return -1; 216 } 217 } else if (bitflips) { 218 pr_info("ignoring error as within bitflip_limit\n"); 219 } 220 221 if (use_offset != 0 || use_len < mtd->oobavail) { 222 int k; 223 224 ops.mode = MTD_OPS_AUTO_OOB; 225 ops.len = 0; 226 ops.retlen = 0; 227 ops.ooblen = mtd->oobavail; 228 ops.oobretlen = 0; 229 ops.ooboffs = 0; 230 ops.datbuf = NULL; 231 ops.oobbuf = readbuf; 232 err = mtd_read_oob(mtd, addr, &ops); 233 if (mtd_is_bitflip(err)) 234 err = 0; 235 236 if (err || ops.oobretlen != mtd->oobavail) { 237 pr_err("error: readoob failed at %#llx\n", 238 (long long)addr); 239 errcnt += 1; 240 return err ? err : -1; 241 } 242 bitflips = memcmpshowoffset(addr, use_offset, 243 readbuf + use_offset, 244 writebuf + (use_len_max * i) + use_offset, 245 use_len); 246 247 /* verify pre-offset area for 0xff */ 248 bitflips += memffshow(addr, 0, readbuf, use_offset); 249 250 /* verify post-(use_offset + use_len) area for 0xff */ 251 k = use_offset + use_len; 252 bitflips += memffshow(addr, k, readbuf + k, 253 mtd->oobavail - k); 254 255 if (bitflips > bitflip_limit) { 256 pr_err("error: verify failed at %#llx\n", 257 (long long)addr); 258 errcnt += 1; 259 if (errcnt > 1000) { 260 pr_err("error: too many errors\n"); 261 return -1; 262 } 263 } else if (bitflips) { 264 pr_info("ignoring errors as within bitflip limit\n"); 265 } 266 } 267 if (vary_offset) 268 do_vary_offset(); 269 } 270 return err; 271 } 272 273 static int verify_eraseblock_in_one_go(int ebnum) 274 { 275 struct mtd_oob_ops ops; 276 int err = 0; 277 loff_t addr = (loff_t)ebnum * mtd->erasesize; 278 size_t len = mtd->oobavail * pgcnt; 279 size_t oobavail = mtd->oobavail; 280 size_t bitflips; 281 int i; 282 283 prandom_bytes_state(&rnd_state, writebuf, len); 284 ops.mode = MTD_OPS_AUTO_OOB; 285 ops.len = 0; 286 ops.retlen = 0; 287 ops.ooblen = len; 288 ops.oobretlen = 0; 289 ops.ooboffs = 0; 290 ops.datbuf = NULL; 291 ops.oobbuf = readbuf; 292 293 /* read entire block's OOB at one go */ 294 err = mtd_read_oob(mtd, addr, &ops); 295 if (mtd_is_bitflip(err)) 296 err = 0; 297 298 if (err || ops.oobretlen != len) { 299 pr_err("error: readoob failed at %#llx\n", 300 (long long)addr); 301 errcnt += 1; 302 return err ? err : -1; 303 } 304 305 /* verify one page OOB at a time for bitflip per page limit check */ 306 for (i = 0; i < pgcnt; ++i, addr += mtd->writesize) { 307 bitflips = memcmpshow(addr, readbuf + (i * oobavail), 308 writebuf + (i * oobavail), oobavail); 309 if (bitflips > bitflip_limit) { 310 pr_err("error: verify failed at %#llx\n", 311 (long long)addr); 312 errcnt += 1; 313 if (errcnt > 1000) { 314 pr_err("error: too many errors\n"); 315 return -1; 316 } 317 } else if (bitflips) { 318 pr_info("ignoring error as within bitflip_limit\n"); 319 } 320 } 321 322 return err; 323 } 324 325 static int verify_all_eraseblocks(void) 326 { 327 int err; 328 unsigned int i; 329 330 pr_info("verifying all eraseblocks\n"); 331 for (i = 0; i < ebcnt; ++i) { 332 if (bbt[i]) 333 continue; 334 err = verify_eraseblock(i); 335 if (err) 336 return err; 337 if (i % 256 == 0) 338 pr_info("verified up to eraseblock %u\n", i); 339 340 err = mtdtest_relax(); 341 if (err) 342 return err; 343 } 344 pr_info("verified %u eraseblocks\n", i); 345 return 0; 346 } 347 348 static int __init mtd_oobtest_init(void) 349 { 350 int err = 0; 351 unsigned int i; 352 uint64_t tmp; 353 struct mtd_oob_ops ops; 354 loff_t addr = 0, addr0; 355 356 printk(KERN_INFO "\n"); 357 printk(KERN_INFO "=================================================\n"); 358 359 if (dev < 0) { 360 pr_info("Please specify a valid mtd-device via module parameter\n"); 361 pr_crit("CAREFUL: This test wipes all data on the specified MTD device!\n"); 362 return -EINVAL; 363 } 364 365 pr_info("MTD device: %d\n", dev); 366 367 mtd = get_mtd_device(NULL, dev); 368 if (IS_ERR(mtd)) { 369 err = PTR_ERR(mtd); 370 pr_err("error: cannot get MTD device\n"); 371 return err; 372 } 373 374 if (!mtd_type_is_nand(mtd)) { 375 pr_info("this test requires NAND flash\n"); 376 goto out; 377 } 378 379 tmp = mtd->size; 380 do_div(tmp, mtd->erasesize); 381 ebcnt = tmp; 382 pgcnt = mtd->erasesize / mtd->writesize; 383 384 pr_info("MTD device size %llu, eraseblock size %u, " 385 "page size %u, count of eraseblocks %u, pages per " 386 "eraseblock %u, OOB size %u\n", 387 (unsigned long long)mtd->size, mtd->erasesize, 388 mtd->writesize, ebcnt, pgcnt, mtd->oobsize); 389 390 err = -ENOMEM; 391 readbuf = kmalloc(mtd->erasesize, GFP_KERNEL); 392 if (!readbuf) 393 goto out; 394 writebuf = kmalloc(mtd->erasesize, GFP_KERNEL); 395 if (!writebuf) 396 goto out; 397 bbt = kzalloc(ebcnt, GFP_KERNEL); 398 if (!bbt) 399 goto out; 400 401 err = mtdtest_scan_for_bad_eraseblocks(mtd, bbt, 0, ebcnt); 402 if (err) 403 goto out; 404 405 use_offset = 0; 406 use_len = mtd->oobavail; 407 use_len_max = mtd->oobavail; 408 vary_offset = 0; 409 410 /* First test: write all OOB, read it back and verify */ 411 pr_info("test 1 of 5\n"); 412 413 err = mtdtest_erase_good_eraseblocks(mtd, bbt, 0, ebcnt); 414 if (err) 415 goto out; 416 417 prandom_seed_state(&rnd_state, 1); 418 err = write_whole_device(); 419 if (err) 420 goto out; 421 422 prandom_seed_state(&rnd_state, 1); 423 err = verify_all_eraseblocks(); 424 if (err) 425 goto out; 426 427 /* 428 * Second test: write all OOB, a block at a time, read it back and 429 * verify. 430 */ 431 pr_info("test 2 of 5\n"); 432 433 err = mtdtest_erase_good_eraseblocks(mtd, bbt, 0, ebcnt); 434 if (err) 435 goto out; 436 437 prandom_seed_state(&rnd_state, 3); 438 err = write_whole_device(); 439 if (err) 440 goto out; 441 442 /* Check all eraseblocks */ 443 prandom_seed_state(&rnd_state, 3); 444 pr_info("verifying all eraseblocks\n"); 445 for (i = 0; i < ebcnt; ++i) { 446 if (bbt[i]) 447 continue; 448 err = verify_eraseblock_in_one_go(i); 449 if (err) 450 goto out; 451 if (i % 256 == 0) 452 pr_info("verified up to eraseblock %u\n", i); 453 454 err = mtdtest_relax(); 455 if (err) 456 goto out; 457 } 458 pr_info("verified %u eraseblocks\n", i); 459 460 /* 461 * Third test: write OOB at varying offsets and lengths, read it back 462 * and verify. 463 */ 464 pr_info("test 3 of 5\n"); 465 466 err = mtdtest_erase_good_eraseblocks(mtd, bbt, 0, ebcnt); 467 if (err) 468 goto out; 469 470 /* Write all eraseblocks */ 471 use_offset = 0; 472 use_len = mtd->oobavail; 473 use_len_max = mtd->oobavail; 474 vary_offset = 1; 475 prandom_seed_state(&rnd_state, 5); 476 477 err = write_whole_device(); 478 if (err) 479 goto out; 480 481 /* Check all eraseblocks */ 482 use_offset = 0; 483 use_len = mtd->oobavail; 484 use_len_max = mtd->oobavail; 485 vary_offset = 1; 486 prandom_seed_state(&rnd_state, 5); 487 err = verify_all_eraseblocks(); 488 if (err) 489 goto out; 490 491 use_offset = 0; 492 use_len = mtd->oobavail; 493 use_len_max = mtd->oobavail; 494 vary_offset = 0; 495 496 /* Fourth test: try to write off end of device */ 497 pr_info("test 4 of 5\n"); 498 499 err = mtdtest_erase_good_eraseblocks(mtd, bbt, 0, ebcnt); 500 if (err) 501 goto out; 502 503 addr0 = 0; 504 for (i = 0; i < ebcnt && bbt[i]; ++i) 505 addr0 += mtd->erasesize; 506 507 /* Attempt to write off end of OOB */ 508 ops.mode = MTD_OPS_AUTO_OOB; 509 ops.len = 0; 510 ops.retlen = 0; 511 ops.ooblen = 1; 512 ops.oobretlen = 0; 513 ops.ooboffs = mtd->oobavail; 514 ops.datbuf = NULL; 515 ops.oobbuf = writebuf; 516 pr_info("attempting to start write past end of OOB\n"); 517 pr_info("an error is expected...\n"); 518 err = mtd_write_oob(mtd, addr0, &ops); 519 if (err) { 520 pr_info("error occurred as expected\n"); 521 err = 0; 522 } else { 523 pr_err("error: can write past end of OOB\n"); 524 errcnt += 1; 525 } 526 527 /* Attempt to read off end of OOB */ 528 ops.mode = MTD_OPS_AUTO_OOB; 529 ops.len = 0; 530 ops.retlen = 0; 531 ops.ooblen = 1; 532 ops.oobretlen = 0; 533 ops.ooboffs = mtd->oobavail; 534 ops.datbuf = NULL; 535 ops.oobbuf = readbuf; 536 pr_info("attempting to start read past end of OOB\n"); 537 pr_info("an error is expected...\n"); 538 err = mtd_read_oob(mtd, addr0, &ops); 539 if (mtd_is_bitflip(err)) 540 err = 0; 541 542 if (err) { 543 pr_info("error occurred as expected\n"); 544 err = 0; 545 } else { 546 pr_err("error: can read past end of OOB\n"); 547 errcnt += 1; 548 } 549 550 if (bbt[ebcnt - 1]) 551 pr_info("skipping end of device tests because last " 552 "block is bad\n"); 553 else { 554 /* Attempt to write off end of device */ 555 ops.mode = MTD_OPS_AUTO_OOB; 556 ops.len = 0; 557 ops.retlen = 0; 558 ops.ooblen = mtd->oobavail + 1; 559 ops.oobretlen = 0; 560 ops.ooboffs = 0; 561 ops.datbuf = NULL; 562 ops.oobbuf = writebuf; 563 pr_info("attempting to write past end of device\n"); 564 pr_info("an error is expected...\n"); 565 err = mtd_write_oob(mtd, mtd->size - mtd->writesize, &ops); 566 if (err) { 567 pr_info("error occurred as expected\n"); 568 err = 0; 569 } else { 570 pr_err("error: wrote past end of device\n"); 571 errcnt += 1; 572 } 573 574 /* Attempt to read off end of device */ 575 ops.mode = MTD_OPS_AUTO_OOB; 576 ops.len = 0; 577 ops.retlen = 0; 578 ops.ooblen = mtd->oobavail + 1; 579 ops.oobretlen = 0; 580 ops.ooboffs = 0; 581 ops.datbuf = NULL; 582 ops.oobbuf = readbuf; 583 pr_info("attempting to read past end of device\n"); 584 pr_info("an error is expected...\n"); 585 err = mtd_read_oob(mtd, mtd->size - mtd->writesize, &ops); 586 if (mtd_is_bitflip(err)) 587 err = 0; 588 589 if (err) { 590 pr_info("error occurred as expected\n"); 591 err = 0; 592 } else { 593 pr_err("error: read past end of device\n"); 594 errcnt += 1; 595 } 596 597 err = mtdtest_erase_eraseblock(mtd, ebcnt - 1); 598 if (err) 599 goto out; 600 601 /* Attempt to write off end of device */ 602 ops.mode = MTD_OPS_AUTO_OOB; 603 ops.len = 0; 604 ops.retlen = 0; 605 ops.ooblen = mtd->oobavail; 606 ops.oobretlen = 0; 607 ops.ooboffs = 1; 608 ops.datbuf = NULL; 609 ops.oobbuf = writebuf; 610 pr_info("attempting to write past end of device\n"); 611 pr_info("an error is expected...\n"); 612 err = mtd_write_oob(mtd, mtd->size - mtd->writesize, &ops); 613 if (err) { 614 pr_info("error occurred as expected\n"); 615 err = 0; 616 } else { 617 pr_err("error: wrote past end of device\n"); 618 errcnt += 1; 619 } 620 621 /* Attempt to read off end of device */ 622 ops.mode = MTD_OPS_AUTO_OOB; 623 ops.len = 0; 624 ops.retlen = 0; 625 ops.ooblen = mtd->oobavail; 626 ops.oobretlen = 0; 627 ops.ooboffs = 1; 628 ops.datbuf = NULL; 629 ops.oobbuf = readbuf; 630 pr_info("attempting to read past end of device\n"); 631 pr_info("an error is expected...\n"); 632 err = mtd_read_oob(mtd, mtd->size - mtd->writesize, &ops); 633 if (mtd_is_bitflip(err)) 634 err = 0; 635 636 if (err) { 637 pr_info("error occurred as expected\n"); 638 err = 0; 639 } else { 640 pr_err("error: read past end of device\n"); 641 errcnt += 1; 642 } 643 } 644 645 /* Fifth test: write / read across block boundaries */ 646 pr_info("test 5 of 5\n"); 647 648 /* Erase all eraseblocks */ 649 err = mtdtest_erase_good_eraseblocks(mtd, bbt, 0, ebcnt); 650 if (err) 651 goto out; 652 653 /* Write all eraseblocks */ 654 prandom_seed_state(&rnd_state, 11); 655 pr_info("writing OOBs of whole device\n"); 656 for (i = 0; i < ebcnt - 1; ++i) { 657 int cnt = 2; 658 int pg; 659 size_t sz = mtd->oobavail; 660 if (bbt[i] || bbt[i + 1]) 661 continue; 662 addr = (loff_t)(i + 1) * mtd->erasesize - mtd->writesize; 663 prandom_bytes_state(&rnd_state, writebuf, sz * cnt); 664 for (pg = 0; pg < cnt; ++pg) { 665 ops.mode = MTD_OPS_AUTO_OOB; 666 ops.len = 0; 667 ops.retlen = 0; 668 ops.ooblen = sz; 669 ops.oobretlen = 0; 670 ops.ooboffs = 0; 671 ops.datbuf = NULL; 672 ops.oobbuf = writebuf + pg * sz; 673 err = mtd_write_oob(mtd, addr, &ops); 674 if (err) 675 goto out; 676 if (i % 256 == 0) 677 pr_info("written up to eraseblock %u\n", i); 678 679 err = mtdtest_relax(); 680 if (err) 681 goto out; 682 683 addr += mtd->writesize; 684 } 685 } 686 pr_info("written %u eraseblocks\n", i); 687 688 /* Check all eraseblocks */ 689 prandom_seed_state(&rnd_state, 11); 690 pr_info("verifying all eraseblocks\n"); 691 for (i = 0; i < ebcnt - 1; ++i) { 692 if (bbt[i] || bbt[i + 1]) 693 continue; 694 prandom_bytes_state(&rnd_state, writebuf, mtd->oobavail * 2); 695 addr = (loff_t)(i + 1) * mtd->erasesize - mtd->writesize; 696 ops.mode = MTD_OPS_AUTO_OOB; 697 ops.len = 0; 698 ops.retlen = 0; 699 ops.ooblen = mtd->oobavail * 2; 700 ops.oobretlen = 0; 701 ops.ooboffs = 0; 702 ops.datbuf = NULL; 703 ops.oobbuf = readbuf; 704 err = mtd_read_oob(mtd, addr, &ops); 705 if (mtd_is_bitflip(err)) 706 err = 0; 707 708 if (err) 709 goto out; 710 if (memcmpshow(addr, readbuf, writebuf, 711 mtd->oobavail * 2)) { 712 pr_err("error: verify failed at %#llx\n", 713 (long long)addr); 714 errcnt += 1; 715 if (errcnt > 1000) { 716 pr_err("error: too many errors\n"); 717 goto out; 718 } 719 } 720 if (i % 256 == 0) 721 pr_info("verified up to eraseblock %u\n", i); 722 723 err = mtdtest_relax(); 724 if (err) 725 goto out; 726 } 727 pr_info("verified %u eraseblocks\n", i); 728 729 pr_info("finished with %d errors\n", errcnt); 730 out: 731 kfree(bbt); 732 kfree(writebuf); 733 kfree(readbuf); 734 put_mtd_device(mtd); 735 if (err) 736 pr_info("error %d occurred\n", err); 737 printk(KERN_INFO "=================================================\n"); 738 return err; 739 } 740 module_init(mtd_oobtest_init); 741 742 static void __exit mtd_oobtest_exit(void) 743 { 744 return; 745 } 746 module_exit(mtd_oobtest_exit); 747 748 MODULE_DESCRIPTION("Out-of-band test module"); 749 MODULE_AUTHOR("Adrian Hunter"); 750 MODULE_LICENSE("GPL"); 751