drivers/mtd/tests/oobtest.c - pub/scm/linux/kernel/git/atull/linux-fpga - Git at Google

 /*
  * Copyright (C) 2006-2008 Nokia Corporation
  *
  * This program is free software; you can redistribute it and/or modify it
  * under the terms of the GNU General Public License version 2 as published by
  * the Free Software Foundation.
  *
  * This program is distributed in the hope that it will be useful, but WITHOUT
  * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
  * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for
  * more details.
  *
  * You should have received a copy of the GNU General Public License along with
  * this program; see the file COPYING. If not, write to the Free Software
  * Foundation, 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
  *
  * Test OOB read and write on MTD device.
  *
  * Author: Adrian Hunter <ext-adrian.hunter@nokia.com>
  */

 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt

 #include <asm/div64.h>
 #include <linux/init.h>
 #include <linux/module.h>
 #include <linux/moduleparam.h>
 #include <linux/err.h>
 #include <linux/mtd/mtd.h>
 #include <linux/slab.h>
 #include <linux/sched.h>
 #include <linux/random.h>

 #include "mtd_test.h"

 static int dev = -EINVAL;
 static int bitflip_limit;
 module_param(dev, int, S_IRUGO);
 MODULE_PARM_DESC(dev, "MTD device number to use");
 module_param(bitflip_limit, int, S_IRUGO);
 MODULE_PARM_DESC(bitflip_limit, "Max. allowed bitflips per page");

 static struct mtd_info *mtd;
 static unsigned char *readbuf;
 static unsigned char *writebuf;
 static unsigned char *bbt;

 static int ebcnt;
 static int pgcnt;
 static int errcnt;
 static int use_offset;
 static int use_len;
 static int use_len_max;
 static int vary_offset;
 static struct rnd_state rnd_state;

 static void do_vary_offset(void)
 {
 	use_len -= 1;
 	if (use_len < 1) {
 		use_offset += 1;
 		if (use_offset >= use_len_max)
 			use_offset = 0;
 		use_len = use_len_max - use_offset;
 	}
 }

 static int write_eraseblock(int ebnum)
 {
 	int i;
 	struct mtd_oob_ops ops;
 	int err = 0;
 	loff_t addr = (loff_t)ebnum * mtd->erasesize;

 	prandom_bytes_state(&rnd_state, writebuf, use_len_max * pgcnt);
 	for (i = 0; i < pgcnt; ++i, addr += mtd->writesize) {
 		ops.mode      = MTD_OPS_AUTO_OOB;
 		ops.len       = 0;
 		ops.retlen    = 0;
 		ops.ooblen    = use_len;
 		ops.oobretlen = 0;
 		ops.ooboffs   = use_offset;
 		ops.datbuf    = NULL;
 		ops.oobbuf    = writebuf + (use_len_max * i) + use_offset;
 		err = mtd_write_oob(mtd, addr, &ops);
 		if (err || ops.oobretlen != use_len) {
 			pr_err("error: writeoob failed at %#llx\n",
 			       (long long)addr);
 			pr_err("error: use_len %d, use_offset %d\n",
 			       use_len, use_offset);
 			errcnt += 1;
 			return err ? err : -1;
 		}
 		if (vary_offset)
 			do_vary_offset();
 	}

 	return err;
 }

 static int write_whole_device(void)
 {
 	int err;
 	unsigned int i;

 	pr_info("writing OOBs of whole device\n");
 	for (i = 0; i < ebcnt; ++i) {
 		if (bbt[i])
 			continue;
 		err = write_eraseblock(i);
 		if (err)
 			return err;
 		if (i % 256 == 0)
 			pr_info("written up to eraseblock %u\n", i);

 		err = mtdtest_relax();
 		if (err)
 			return err;
 	}
 	pr_info("written %u eraseblocks\n", i);
 	return 0;
 }

 /*
  * Display the address, offset and data bytes at comparison failure.
  * Return number of bitflips encountered.
  */
 static size_t memcmpshowoffset(loff_t addr, loff_t offset, const void *cs,
 			       const void *ct, size_t count)
 {
 	const unsigned char *su1, *su2;
 	int res;
 	size_t i = 0;
 	size_t bitflips = 0;

 	for (su1 = cs, su2 = ct; 0 < count; ++su1, ++su2, count--, i++) {
 		res = *su1 ^ *su2;
 		if (res) {
 			pr_info("error @addr[0x%lx:0x%lx] 0x%x -> 0x%x diff 0x%x\n",
 				(unsigned long)addr, (unsigned long)offset + i,
 				*su1, *su2, res);
 			bitflips += hweight8(res);
 		}
 	}

 	return bitflips;
 }

 #define memcmpshow(addr, cs, ct, count) memcmpshowoffset((addr), 0, (cs), (ct),\
 							 (count))

 /*
  * Compare with 0xff and show the address, offset and data bytes at
  * comparison failure. Return number of bitflips encountered.
  */
 static size_t memffshow(loff_t addr, loff_t offset, const void *cs,
 			size_t count)
 {
 	const unsigned char *su1;
 	int res;
 	size_t i = 0;
 	size_t bitflips = 0;

 	for (su1 = cs; 0 < count; ++su1, count--, i++) {
 		res = *su1 ^ 0xff;
 		if (res) {
 			pr_info("error @addr[0x%lx:0x%lx] 0x%x -> 0xff diff 0x%x\n",
 				(unsigned long)addr, (unsigned long)offset + i,
 				*su1, res);
 			bitflips += hweight8(res);
 		}
 	}

 	return bitflips;
 }

 static int verify_eraseblock(int ebnum)
 {
 	int i;
 	struct mtd_oob_ops ops;
 	int err = 0;
 	loff_t addr = (loff_t)ebnum * mtd->erasesize;
 	size_t bitflips;

 	prandom_bytes_state(&rnd_state, writebuf, use_len_max * pgcnt);
 	for (i = 0; i < pgcnt; ++i, addr += mtd->writesize) {
 		ops.mode      = MTD_OPS_AUTO_OOB;
 		ops.len       = 0;
 		ops.retlen    = 0;
 		ops.ooblen    = use_len;
 		ops.oobretlen = 0;
 		ops.ooboffs   = use_offset;
 		ops.datbuf    = NULL;
 		ops.oobbuf    = readbuf;
 		err = mtd_read_oob(mtd, addr, &ops);
 		if (err || ops.oobretlen != use_len) {
 			pr_err("error: readoob failed at %#llx\n",
 			       (long long)addr);
 			errcnt += 1;
 			return err ? err : -1;
 		}

 		bitflips = memcmpshow(addr, readbuf,
 				      writebuf + (use_len_max * i) + use_offset,
 				      use_len);
 		if (bitflips > bitflip_limit) {
 			pr_err("error: verify failed at %#llx\n",
 			       (long long)addr);
 			errcnt += 1;
 			if (errcnt > 1000) {
 				pr_err("error: too many errors\n");
 				return -1;
 			}
 		} else if (bitflips) {
 			pr_info("ignoring error as within bitflip_limit\n");
 		}

 		if (use_offset != 0 || use_len < mtd->oobavail) {
 			int k;

 			ops.mode      = MTD_OPS_AUTO_OOB;
 			ops.len       = 0;
 			ops.retlen    = 0;
 			ops.ooblen    = mtd->oobavail;
 			ops.oobretlen = 0;
 			ops.ooboffs   = 0;
 			ops.datbuf    = NULL;
 			ops.oobbuf    = readbuf;
 			err = mtd_read_oob(mtd, addr, &ops);
 			if (err || ops.oobretlen != mtd->oobavail) {
 				pr_err("error: readoob failed at %#llx\n",
 						(long long)addr);
 				errcnt += 1;
 				return err ? err : -1;
 			}
 			bitflips = memcmpshowoffset(addr, use_offset,
 						    readbuf + use_offset,
 						    writebuf + (use_len_max * i) + use_offset,
 						    use_len);

 			/* verify pre-offset area for 0xff */
 			bitflips += memffshow(addr, 0, readbuf, use_offset);

 			/* verify post-(use_offset + use_len) area for 0xff */
 			k = use_offset + use_len;
 			bitflips += memffshow(addr, k, readbuf + k,
 					      mtd->oobavail - k);

 			if (bitflips > bitflip_limit) {
 				pr_err("error: verify failed at %#llx\n",
 						(long long)addr);
 				errcnt += 1;
 				if (errcnt > 1000) {
 					pr_err("error: too many errors\n");
 					return -1;
 				}
 			} else if (bitflips) {
 				pr_info("ignoring errors as within bitflip limit\n");
 			}
 		}
 		if (vary_offset)
 			do_vary_offset();
 	}
 	return err;
 }

 static int verify_eraseblock_in_one_go(int ebnum)
 {
 	struct mtd_oob_ops ops;
 	int err = 0;
 	loff_t addr = (loff_t)ebnum * mtd->erasesize;
 	size_t len = mtd->oobavail * pgcnt;
 	size_t oobavail = mtd->oobavail;
 	size_t bitflips;
 	int i;

 	prandom_bytes_state(&rnd_state, writebuf, len);
 	ops.mode      = MTD_OPS_AUTO_OOB;
 	ops.len       = 0;
 	ops.retlen    = 0;
 	ops.ooblen    = len;
 	ops.oobretlen = 0;
 	ops.ooboffs   = 0;
 	ops.datbuf    = NULL;
 	ops.oobbuf    = readbuf;

 	/* read entire block's OOB at one go */
 	err = mtd_read_oob(mtd, addr, &ops);
 	if (err || ops.oobretlen != len) {
 		pr_err("error: readoob failed at %#llx\n",
 		       (long long)addr);
 		errcnt += 1;
 		return err ? err : -1;
 	}

 	/* verify one page OOB at a time for bitflip per page limit check */
 	for (i = 0; i < pgcnt; ++i, addr += mtd->writesize) {
 		bitflips = memcmpshow(addr, readbuf + (i * oobavail),
 				      writebuf + (i * oobavail), oobavail);
 		if (bitflips > bitflip_limit) {
 			pr_err("error: verify failed at %#llx\n",
 			       (long long)addr);
 			errcnt += 1;
 			if (errcnt > 1000) {
 				pr_err("error: too many errors\n");
 				return -1;
 			}
 		} else if (bitflips) {
 			pr_info("ignoring error as within bitflip_limit\n");
 		}
 	}

 	return err;
 }

 static int verify_all_eraseblocks(void)
 {
 	int err;
 	unsigned int i;

 	pr_info("verifying all eraseblocks\n");
 	for (i = 0; i < ebcnt; ++i) {
 		if (bbt[i])
 			continue;
 		err = verify_eraseblock(i);
 		if (err)
 			return err;
 		if (i % 256 == 0)
 			pr_info("verified up to eraseblock %u\n", i);

 		err = mtdtest_relax();
 		if (err)
 			return err;
 	}
 	pr_info("verified %u eraseblocks\n", i);
 	return 0;
 }

 static int __init mtd_oobtest_init(void)
 {
 	int err = 0;
 	unsigned int i;
 	uint64_t tmp;
 	struct mtd_oob_ops ops;
 	loff_t addr = 0, addr0;

 	printk(KERN_INFO "\n");
 	printk(KERN_INFO "=================================================\n");

 	if (dev < 0) {
 		pr_info("Please specify a valid mtd-device via module parameter\n");
 		pr_crit("CAREFUL: This test wipes all data on the specified MTD device!\n");
 		return -EINVAL;
 	}

 	pr_info("MTD device: %d\n", dev);

 	mtd = get_mtd_device(NULL, dev);
 	if (IS_ERR(mtd)) {
 		err = PTR_ERR(mtd);
 		pr_err("error: cannot get MTD device\n");
 		return err;
 	}

 	if (!mtd_type_is_nand(mtd)) {
 		pr_info("this test requires NAND flash\n");
 		goto out;
 	}

 	tmp = mtd->size;
 	do_div(tmp, mtd->erasesize);
 	ebcnt = tmp;
 	pgcnt = mtd->erasesize / mtd->writesize;

 	pr_info("MTD device size %llu, eraseblock size %u, "
 	       "page size %u, count of eraseblocks %u, pages per "
 	       "eraseblock %u, OOB size %u\n",
 	       (unsigned long long)mtd->size, mtd->erasesize,
 	       mtd->writesize, ebcnt, pgcnt, mtd->oobsize);

 	err = -ENOMEM;
 	readbuf = kmalloc(mtd->erasesize, GFP_KERNEL);
 	if (!readbuf)
 		goto out;
 	writebuf = kmalloc(mtd->erasesize, GFP_KERNEL);
 	if (!writebuf)
 		goto out;
 	bbt = kzalloc(ebcnt, GFP_KERNEL);
 	if (!bbt)
 		goto out;

 	err = mtdtest_scan_for_bad_eraseblocks(mtd, bbt, 0, ebcnt);
 	if (err)
 		goto out;

 	use_offset = 0;
 	use_len = mtd->oobavail;
 	use_len_max = mtd->oobavail;
 	vary_offset = 0;

 	/* First test: write all OOB, read it back and verify */
 	pr_info("test 1 of 5\n");

 	err = mtdtest_erase_good_eraseblocks(mtd, bbt, 0, ebcnt);
 	if (err)
 		goto out;

 	prandom_seed_state(&rnd_state, 1);
 	err = write_whole_device();
 	if (err)
 		goto out;

 	prandom_seed_state(&rnd_state, 1);
 	err = verify_all_eraseblocks();
 	if (err)
 		goto out;

 	/*
 	 * Second test: write all OOB, a block at a time, read it back and
 	 * verify.
 	 */
 	pr_info("test 2 of 5\n");

 	err = mtdtest_erase_good_eraseblocks(mtd, bbt, 0, ebcnt);
 	if (err)
 		goto out;

 	prandom_seed_state(&rnd_state, 3);
 	err = write_whole_device();
 	if (err)
 		goto out;

 	/* Check all eraseblocks */
 	prandom_seed_state(&rnd_state, 3);
 	pr_info("verifying all eraseblocks\n");
 	for (i = 0; i < ebcnt; ++i) {
 		if (bbt[i])
 			continue;
 		err = verify_eraseblock_in_one_go(i);
 		if (err)
 			goto out;
 		if (i % 256 == 0)
 			pr_info("verified up to eraseblock %u\n", i);

 		err = mtdtest_relax();
 		if (err)
 			goto out;
 	}
 	pr_info("verified %u eraseblocks\n", i);

 	/*
 	 * Third test: write OOB at varying offsets and lengths, read it back
 	 * and verify.
 	 */
 	pr_info("test 3 of 5\n");

 	err = mtdtest_erase_good_eraseblocks(mtd, bbt, 0, ebcnt);
 	if (err)
 		goto out;

 	/* Write all eraseblocks */
 	use_offset = 0;
 	use_len = mtd->oobavail;
 	use_len_max = mtd->oobavail;
 	vary_offset = 1;
 	prandom_seed_state(&rnd_state, 5);

 	err = write_whole_device();
 	if (err)
 		goto out;

 	/* Check all eraseblocks */
 	use_offset = 0;
 	use_len = mtd->oobavail;
 	use_len_max = mtd->oobavail;
 	vary_offset = 1;
 	prandom_seed_state(&rnd_state, 5);
 	err = verify_all_eraseblocks();
 	if (err)
 		goto out;

 	use_offset = 0;
 	use_len = mtd->oobavail;
 	use_len_max = mtd->oobavail;
 	vary_offset = 0;

 	/* Fourth test: try to write off end of device */
 	pr_info("test 4 of 5\n");

 	err = mtdtest_erase_good_eraseblocks(mtd, bbt, 0, ebcnt);
 	if (err)
 		goto out;

 	addr0 = 0;
 	for (i = 0; i < ebcnt && bbt[i]; ++i)
 		addr0 += mtd->erasesize;

 	/* Attempt to write off end of OOB */
 	ops.mode      = MTD_OPS_AUTO_OOB;
 	ops.len       = 0;
 	ops.retlen    = 0;
 	ops.ooblen    = 1;
 	ops.oobretlen = 0;
 	ops.ooboffs   = mtd->oobavail;
 	ops.datbuf    = NULL;
 	ops.oobbuf    = writebuf;
 	pr_info("attempting to start write past end of OOB\n");
 	pr_info("an error is expected...\n");
 	err = mtd_write_oob(mtd, addr0, &ops);
 	if (err) {
 		pr_info("error occurred as expected\n");
 		err = 0;
 	} else {
 		pr_err("error: can write past end of OOB\n");
 		errcnt += 1;
 	}

 	/* Attempt to read off end of OOB */
 	ops.mode      = MTD_OPS_AUTO_OOB;
 	ops.len       = 0;
 	ops.retlen    = 0;
 	ops.ooblen    = 1;
 	ops.oobretlen = 0;
 	ops.ooboffs   = mtd->oobavail;
 	ops.datbuf    = NULL;
 	ops.oobbuf    = readbuf;
 	pr_info("attempting to start read past end of OOB\n");
 	pr_info("an error is expected...\n");
 	err = mtd_read_oob(mtd, addr0, &ops);
 	if (err) {
 		pr_info("error occurred as expected\n");
 		err = 0;
 	} else {
 		pr_err("error: can read past end of OOB\n");
 		errcnt += 1;
 	}

 	if (bbt[ebcnt - 1])
 		pr_info("skipping end of device tests because last "
 		       "block is bad\n");
 	else {
 		/* Attempt to write off end of device */
 		ops.mode      = MTD_OPS_AUTO_OOB;
 		ops.len       = 0;
 		ops.retlen    = 0;
 		ops.ooblen    = mtd->oobavail + 1;
 		ops.oobretlen = 0;
 		ops.ooboffs   = 0;
 		ops.datbuf    = NULL;
 		ops.oobbuf    = writebuf;
 		pr_info("attempting to write past end of device\n");
 		pr_info("an error is expected...\n");
 		err = mtd_write_oob(mtd, mtd->size - mtd->writesize, &ops);
 		if (err) {
 			pr_info("error occurred as expected\n");
 			err = 0;
 		} else {
 			pr_err("error: wrote past end of device\n");
 			errcnt += 1;
 		}

 		/* Attempt to read off end of device */
 		ops.mode      = MTD_OPS_AUTO_OOB;
 		ops.len       = 0;
 		ops.retlen    = 0;
 		ops.ooblen    = mtd->oobavail + 1;
 		ops.oobretlen = 0;
 		ops.ooboffs   = 0;
 		ops.datbuf    = NULL;
 		ops.oobbuf    = readbuf;
 		pr_info("attempting to read past end of device\n");
 		pr_info("an error is expected...\n");
 		err = mtd_read_oob(mtd, mtd->size - mtd->writesize, &ops);
 		if (err) {
 			pr_info("error occurred as expected\n");
 			err = 0;
 		} else {
 			pr_err("error: read past end of device\n");
 			errcnt += 1;
 		}

 		err = mtdtest_erase_eraseblock(mtd, ebcnt - 1);
 		if (err)
 			goto out;

 		/* Attempt to write off end of device */
 		ops.mode      = MTD_OPS_AUTO_OOB;
 		ops.len       = 0;
 		ops.retlen    = 0;
 		ops.ooblen    = mtd->oobavail;
 		ops.oobretlen = 0;
 		ops.ooboffs   = 1;
 		ops.datbuf    = NULL;
 		ops.oobbuf    = writebuf;
 		pr_info("attempting to write past end of device\n");
 		pr_info("an error is expected...\n");
 		err = mtd_write_oob(mtd, mtd->size - mtd->writesize, &ops);
 		if (err) {
 			pr_info("error occurred as expected\n");
 			err = 0;
 		} else {
 			pr_err("error: wrote past end of device\n");
 			errcnt += 1;
 		}

 		/* Attempt to read off end of device */
 		ops.mode      = MTD_OPS_AUTO_OOB;
 		ops.len       = 0;
 		ops.retlen    = 0;
 		ops.ooblen    = mtd->oobavail;
 		ops.oobretlen = 0;
 		ops.ooboffs   = 1;
 		ops.datbuf    = NULL;
 		ops.oobbuf    = readbuf;
 		pr_info("attempting to read past end of device\n");
 		pr_info("an error is expected...\n");
 		err = mtd_read_oob(mtd, mtd->size - mtd->writesize, &ops);
 		if (err) {
 			pr_info("error occurred as expected\n");
 			err = 0;
 		} else {
 			pr_err("error: read past end of device\n");
 			errcnt += 1;
 		}
 	}

 	/* Fifth test: write / read across block boundaries */
 	pr_info("test 5 of 5\n");

 	/* Erase all eraseblocks */
 	err = mtdtest_erase_good_eraseblocks(mtd, bbt, 0, ebcnt);
 	if (err)
 		goto out;

 	/* Write all eraseblocks */
 	prandom_seed_state(&rnd_state, 11);
 	pr_info("writing OOBs of whole device\n");
 	for (i = 0; i < ebcnt - 1; ++i) {
 		int cnt = 2;
 		int pg;
 		size_t sz = mtd->oobavail;
 		if (bbt[i] || bbt[i + 1])
 			continue;
 		addr = (loff_t)(i + 1) * mtd->erasesize - mtd->writesize;
 		prandom_bytes_state(&rnd_state, writebuf, sz * cnt);
 		for (pg = 0; pg < cnt; ++pg) {
 			ops.mode      = MTD_OPS_AUTO_OOB;
 			ops.len       = 0;
 			ops.retlen    = 0;
 			ops.ooblen    = sz;
 			ops.oobretlen = 0;
 			ops.ooboffs   = 0;
 			ops.datbuf    = NULL;
 			ops.oobbuf    = writebuf + pg * sz;
 			err = mtd_write_oob(mtd, addr, &ops);
 			if (err)
 				goto out;
 			if (i % 256 == 0)
 				pr_info("written up to eraseblock %u\n", i);

 			err = mtdtest_relax();
 			if (err)
 				goto out;

 			addr += mtd->writesize;
 		}
 	}
 	pr_info("written %u eraseblocks\n", i);

 	/* Check all eraseblocks */
 	prandom_seed_state(&rnd_state, 11);
 	pr_info("verifying all eraseblocks\n");
 	for (i = 0; i < ebcnt - 1; ++i) {
 		if (bbt[i] || bbt[i + 1])
 			continue;
 		prandom_bytes_state(&rnd_state, writebuf, mtd->oobavail * 2);
 		addr = (loff_t)(i + 1) * mtd->erasesize - mtd->writesize;
 		ops.mode      = MTD_OPS_AUTO_OOB;
 		ops.len       = 0;
 		ops.retlen    = 0;
 		ops.ooblen    = mtd->oobavail * 2;
 		ops.oobretlen = 0;
 		ops.ooboffs   = 0;
 		ops.datbuf    = NULL;
 		ops.oobbuf    = readbuf;
 		err = mtd_read_oob(mtd, addr, &ops);
 		if (err)
 			goto out;
 		if (memcmpshow(addr, readbuf, writebuf,
 			       mtd->oobavail * 2)) {
 			pr_err("error: verify failed at %#llx\n",
 			       (long long)addr);
 			errcnt += 1;
 			if (errcnt > 1000) {
 				pr_err("error: too many errors\n");
 				goto out;
 			}
 		}
 		if (i % 256 == 0)
 			pr_info("verified up to eraseblock %u\n", i);

 		err = mtdtest_relax();
 		if (err)
 			goto out;
 	}
 	pr_info("verified %u eraseblocks\n", i);

 	pr_info("finished with %d errors\n", errcnt);
 out:
 	kfree(bbt);
 	kfree(writebuf);
 	kfree(readbuf);
 	put_mtd_device(mtd);
 	if (err)
 		pr_info("error %d occurred\n", err);
 	printk(KERN_INFO "=================================================\n");
 	return err;
 }
 module_init(mtd_oobtest_init);

 static void __exit mtd_oobtest_exit(void)
 {
 	return;
 }
 module_exit(mtd_oobtest_exit);

 MODULE_DESCRIPTION("Out-of-band test module");
 MODULE_AUTHOR("Adrian Hunter");
 MODULE_LICENSE("GPL");
	/*
	* Copyright (C) 2006-2008 Nokia Corporation
	*
	* This program is free software; you can redistribute it and/or modify it
	* under the terms of the GNU General Public License version 2 as published by
	* the Free Software Foundation.
	*
	* This program is distributed in the hope that it will be useful, but WITHOUT
	* ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
	* FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for
	* more details.
	*
	* You should have received a copy of the GNU General Public License along with
	* this program; see the file COPYING. If not, write to the Free Software
	* Foundation, 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
	*
	* Test OOB read and write on MTD device.
	*
	* Author: Adrian Hunter <ext-adrian.hunter@nokia.com>
	*/

	#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt

	#include <asm/div64.h>
	#include <linux/init.h>
	#include <linux/module.h>
	#include <linux/moduleparam.h>
	#include <linux/err.h>
	#include <linux/mtd/mtd.h>
	#include <linux/slab.h>
	#include <linux/sched.h>
	#include <linux/random.h>

	#include "mtd_test.h"

	static int dev = -EINVAL;
	static int bitflip_limit;
	module_param(dev, int, S_IRUGO);
	MODULE_PARM_DESC(dev, "MTD device number to use");
	module_param(bitflip_limit, int, S_IRUGO);
	MODULE_PARM_DESC(bitflip_limit, "Max. allowed bitflips per page");

	static struct mtd_info *mtd;
	static unsigned char *readbuf;
	static unsigned char *writebuf;
	static unsigned char *bbt;

	static int ebcnt;
	static int pgcnt;
	static int errcnt;
	static int use_offset;
	static int use_len;
	static int use_len_max;
	static int vary_offset;
	static struct rnd_state rnd_state;

	static void do_vary_offset(void)
	{
	use_len -= 1;
	if (use_len < 1) {
	use_offset += 1;
	if (use_offset >= use_len_max)
	use_offset = 0;
	use_len = use_len_max - use_offset;
	}
	}

	static int write_eraseblock(int ebnum)
	{
	int i;
	struct mtd_oob_ops ops;
	int err = 0;
	loff_t addr = (loff_t)ebnum * mtd->erasesize;

	prandom_bytes_state(&rnd_state, writebuf, use_len_max * pgcnt);
	for (i = 0; i < pgcnt; ++i, addr += mtd->writesize) {
	ops.mode = MTD_OPS_AUTO_OOB;
	ops.len = 0;
	ops.retlen = 0;
	ops.ooblen = use_len;
	ops.oobretlen = 0;
	ops.ooboffs = use_offset;
	ops.datbuf = NULL;
	ops.oobbuf = writebuf + (use_len_max * i) + use_offset;
	err = mtd_write_oob(mtd, addr, &ops);
	if (err \|\| ops.oobretlen != use_len) {
	pr_err("error: writeoob failed at %#llx\n",
	(long long)addr);
	pr_err("error: use_len %d, use_offset %d\n",
	use_len, use_offset);
	errcnt += 1;
	return err ? err : -1;
	}
	if (vary_offset)
	do_vary_offset();
	}

	return err;
	}

	static int write_whole_device(void)
	{
	int err;
	unsigned int i;

	pr_info("writing OOBs of whole device\n");
	for (i = 0; i < ebcnt; ++i) {
	if (bbt[i])
	continue;
	err = write_eraseblock(i);
	if (err)
	return err;
	if (i % 256 == 0)
	pr_info("written up to eraseblock %u\n", i);

	err = mtdtest_relax();
	if (err)
	return err;
	}
	pr_info("written %u eraseblocks\n", i);
	return 0;
	}

	/*
	* Display the address, offset and data bytes at comparison failure.
	* Return number of bitflips encountered.
	*/
	static size_t memcmpshowoffset(loff_t addr, loff_t offset, const void *cs,
	const void *ct, size_t count)
	{
	const unsigned char su1, su2;
	int res;
	size_t i = 0;
	size_t bitflips = 0;

	for (su1 = cs, su2 = ct; 0 < count; ++su1, ++su2, count--, i++) {
	res = su1 ^ su2;
	if (res) {
	pr_info("error @addr[0x%lx:0x%lx] 0x%x -> 0x%x diff 0x%x\n",
	(unsigned long)addr, (unsigned long)offset + i,
	su1, su2, res);
	bitflips += hweight8(res);
	}
	}

	return bitflips;
	}

	#define memcmpshow(addr, cs, ct, count) memcmpshowoffset((addr), 0, (cs), (ct),\
	(count))

	/*
	* Compare with 0xff and show the address, offset and data bytes at
	* comparison failure. Return number of bitflips encountered.
	*/
	static size_t memffshow(loff_t addr, loff_t offset, const void *cs,
	size_t count)
	{
	const unsigned char *su1;
	int res;
	size_t i = 0;
	size_t bitflips = 0;

	for (su1 = cs; 0 < count; ++su1, count--, i++) {
	res = *su1 ^ 0xff;
	if (res) {
	pr_info("error @addr[0x%lx:0x%lx] 0x%x -> 0xff diff 0x%x\n",
	(unsigned long)addr, (unsigned long)offset + i,
	*su1, res);
	bitflips += hweight8(res);
	}
	}

	return bitflips;
	}

	static int verify_eraseblock(int ebnum)
	{
	int i;
	struct mtd_oob_ops ops;
	int err = 0;
	loff_t addr = (loff_t)ebnum * mtd->erasesize;
	size_t bitflips;

	prandom_bytes_state(&rnd_state, writebuf, use_len_max * pgcnt);
	for (i = 0; i < pgcnt; ++i, addr += mtd->writesize) {
	ops.mode = MTD_OPS_AUTO_OOB;
	ops.len = 0;
	ops.retlen = 0;
	ops.ooblen = use_len;
	ops.oobretlen = 0;
	ops.ooboffs = use_offset;
	ops.datbuf = NULL;
	ops.oobbuf = readbuf;
	err = mtd_read_oob(mtd, addr, &ops);
	if (err \|\| ops.oobretlen != use_len) {
	pr_err("error: readoob failed at %#llx\n",
	(long long)addr);
	errcnt += 1;
	return err ? err : -1;
	}

	bitflips = memcmpshow(addr, readbuf,
	writebuf + (use_len_max * i) + use_offset,
	use_len);
	if (bitflips > bitflip_limit) {
	pr_err("error: verify failed at %#llx\n",
	(long long)addr);
	errcnt += 1;
	if (errcnt > 1000) {
	pr_err("error: too many errors\n");
	return -1;
	}
	} else if (bitflips) {
	pr_info("ignoring error as within bitflip_limit\n");
	}

	if (use_offset != 0 \|\| use_len < mtd->oobavail) {
	int k;

	ops.mode = MTD_OPS_AUTO_OOB;
	ops.len = 0;
	ops.retlen = 0;
	ops.ooblen = mtd->oobavail;
	ops.oobretlen = 0;
	ops.ooboffs = 0;
	ops.datbuf = NULL;
	ops.oobbuf = readbuf;
	err = mtd_read_oob(mtd, addr, &ops);
	if (err \|\| ops.oobretlen != mtd->oobavail) {
	pr_err("error: readoob failed at %#llx\n",
	(long long)addr);
	errcnt += 1;
	return err ? err : -1;
	}
	bitflips = memcmpshowoffset(addr, use_offset,
	readbuf + use_offset,
	writebuf + (use_len_max * i) + use_offset,
	use_len);

	/* verify pre-offset area for 0xff */
	bitflips += memffshow(addr, 0, readbuf, use_offset);

	/* verify post-(use_offset + use_len) area for 0xff */
	k = use_offset + use_len;
	bitflips += memffshow(addr, k, readbuf + k,
	mtd->oobavail - k);

	if (bitflips > bitflip_limit) {
	pr_err("error: verify failed at %#llx\n",
	(long long)addr);
	errcnt += 1;
	if (errcnt > 1000) {
	pr_err("error: too many errors\n");
	return -1;
	}
	} else if (bitflips) {
	pr_info("ignoring errors as within bitflip limit\n");
	}
	}
	if (vary_offset)
	do_vary_offset();
	}
	return err;
	}

	static int verify_eraseblock_in_one_go(int ebnum)
	{
	struct mtd_oob_ops ops;
	int err = 0;
	loff_t addr = (loff_t)ebnum * mtd->erasesize;
	size_t len = mtd->oobavail * pgcnt;
	size_t oobavail = mtd->oobavail;
	size_t bitflips;
	int i;

	prandom_bytes_state(&rnd_state, writebuf, len);
	ops.mode = MTD_OPS_AUTO_OOB;
	ops.len = 0;
	ops.retlen = 0;
	ops.ooblen = len;
	ops.oobretlen = 0;
	ops.ooboffs = 0;
	ops.datbuf = NULL;
	ops.oobbuf = readbuf;

	/* read entire block's OOB at one go */
	err = mtd_read_oob(mtd, addr, &ops);
	if (err \|\| ops.oobretlen != len) {
	pr_err("error: readoob failed at %#llx\n",
	(long long)addr);
	errcnt += 1;
	return err ? err : -1;
	}

	/* verify one page OOB at a time for bitflip per page limit check */
	for (i = 0; i < pgcnt; ++i, addr += mtd->writesize) {
	bitflips = memcmpshow(addr, readbuf + (i * oobavail),
	writebuf + (i * oobavail), oobavail);
	if (bitflips > bitflip_limit) {
	pr_err("error: verify failed at %#llx\n",
	(long long)addr);
	errcnt += 1;
	if (errcnt > 1000) {
	pr_err("error: too many errors\n");
	return -1;
	}
	} else if (bitflips) {
	pr_info("ignoring error as within bitflip_limit\n");
	}
	}

	return err;
	}

	static int verify_all_eraseblocks(void)
	{
	int err;
	unsigned int i;

	pr_info("verifying all eraseblocks\n");
	for (i = 0; i < ebcnt; ++i) {
	if (bbt[i])
	continue;
	err = verify_eraseblock(i);
	if (err)
	return err;
	if (i % 256 == 0)
	pr_info("verified up to eraseblock %u\n", i);

	err = mtdtest_relax();
	if (err)
	return err;
	}
	pr_info("verified %u eraseblocks\n", i);
	return 0;
	}

	static int __init mtd_oobtest_init(void)
	{
	int err = 0;
	unsigned int i;
	uint64_t tmp;
	struct mtd_oob_ops ops;
	loff_t addr = 0, addr0;

	printk(KERN_INFO "\n");
	printk(KERN_INFO "=================================================\n");

	if (dev < 0) {
	pr_info("Please specify a valid mtd-device via module parameter\n");
	pr_crit("CAREFUL: This test wipes all data on the specified MTD device!\n");
	return -EINVAL;
	}

	pr_info("MTD device: %d\n", dev);

	mtd = get_mtd_device(NULL, dev);
	if (IS_ERR(mtd)) {
	err = PTR_ERR(mtd);
	pr_err("error: cannot get MTD device\n");
	return err;
	}

	if (!mtd_type_is_nand(mtd)) {
	pr_info("this test requires NAND flash\n");
	goto out;
	}

	tmp = mtd->size;
	do_div(tmp, mtd->erasesize);
	ebcnt = tmp;
	pgcnt = mtd->erasesize / mtd->writesize;

	pr_info("MTD device size %llu, eraseblock size %u, "
	"page size %u, count of eraseblocks %u, pages per "
	"eraseblock %u, OOB size %u\n",
	(unsigned long long)mtd->size, mtd->erasesize,
	mtd->writesize, ebcnt, pgcnt, mtd->oobsize);

	err = -ENOMEM;
	readbuf = kmalloc(mtd->erasesize, GFP_KERNEL);
	if (!readbuf)
	goto out;
	writebuf = kmalloc(mtd->erasesize, GFP_KERNEL);
	if (!writebuf)
	goto out;
	bbt = kzalloc(ebcnt, GFP_KERNEL);
	if (!bbt)
	goto out;

	err = mtdtest_scan_for_bad_eraseblocks(mtd, bbt, 0, ebcnt);
	if (err)
	goto out;

	use_offset = 0;
	use_len = mtd->oobavail;
	use_len_max = mtd->oobavail;
	vary_offset = 0;

	/* First test: write all OOB, read it back and verify */
	pr_info("test 1 of 5\n");

	err = mtdtest_erase_good_eraseblocks(mtd, bbt, 0, ebcnt);
	if (err)
	goto out;

	prandom_seed_state(&rnd_state, 1);
	err = write_whole_device();
	if (err)
	goto out;

	prandom_seed_state(&rnd_state, 1);
	err = verify_all_eraseblocks();
	if (err)
	goto out;

	/*
	* Second test: write all OOB, a block at a time, read it back and
	* verify.
	*/
	pr_info("test 2 of 5\n");

	err = mtdtest_erase_good_eraseblocks(mtd, bbt, 0, ebcnt);
	if (err)
	goto out;

	prandom_seed_state(&rnd_state, 3);
	err = write_whole_device();
	if (err)
	goto out;

	/* Check all eraseblocks */
	prandom_seed_state(&rnd_state, 3);
	pr_info("verifying all eraseblocks\n");
	for (i = 0; i < ebcnt; ++i) {
	if (bbt[i])
	continue;
	err = verify_eraseblock_in_one_go(i);
	if (err)
	goto out;
	if (i % 256 == 0)
	pr_info("verified up to eraseblock %u\n", i);

	err = mtdtest_relax();
	if (err)
	goto out;
	}
	pr_info("verified %u eraseblocks\n", i);

	/*
	* Third test: write OOB at varying offsets and lengths, read it back
	* and verify.
	*/
	pr_info("test 3 of 5\n");

	err = mtdtest_erase_good_eraseblocks(mtd, bbt, 0, ebcnt);
	if (err)
	goto out;

	/* Write all eraseblocks */
	use_offset = 0;
	use_len = mtd->oobavail;
	use_len_max = mtd->oobavail;
	vary_offset = 1;
	prandom_seed_state(&rnd_state, 5);

	err = write_whole_device();
	if (err)
	goto out;

	/* Check all eraseblocks */
	use_offset = 0;
	use_len = mtd->oobavail;
	use_len_max = mtd->oobavail;
	vary_offset = 1;
	prandom_seed_state(&rnd_state, 5);
	err = verify_all_eraseblocks();
	if (err)
	goto out;

	use_offset = 0;
	use_len = mtd->oobavail;
	use_len_max = mtd->oobavail;
	vary_offset = 0;

	/* Fourth test: try to write off end of device */
	pr_info("test 4 of 5\n");

	err = mtdtest_erase_good_eraseblocks(mtd, bbt, 0, ebcnt);
	if (err)
	goto out;

	addr0 = 0;
	for (i = 0; i < ebcnt && bbt[i]; ++i)
	addr0 += mtd->erasesize;

	/* Attempt to write off end of OOB */
	ops.mode = MTD_OPS_AUTO_OOB;
	ops.len = 0;
	ops.retlen = 0;
	ops.ooblen = 1;
	ops.oobretlen = 0;
	ops.ooboffs = mtd->oobavail;
	ops.datbuf = NULL;
	ops.oobbuf = writebuf;
	pr_info("attempting to start write past end of OOB\n");
	pr_info("an error is expected...\n");
	err = mtd_write_oob(mtd, addr0, &ops);
	if (err) {
	pr_info("error occurred as expected\n");
	err = 0;
	} else {
	pr_err("error: can write past end of OOB\n");
	errcnt += 1;
	}

	/* Attempt to read off end of OOB */
	ops.mode = MTD_OPS_AUTO_OOB;
	ops.len = 0;
	ops.retlen = 0;
	ops.ooblen = 1;
	ops.oobretlen = 0;
	ops.ooboffs = mtd->oobavail;
	ops.datbuf = NULL;
	ops.oobbuf = readbuf;
	pr_info("attempting to start read past end of OOB\n");
	pr_info("an error is expected...\n");
	err = mtd_read_oob(mtd, addr0, &ops);
	if (err) {
	pr_info("error occurred as expected\n");
	err = 0;
	} else {
	pr_err("error: can read past end of OOB\n");
	errcnt += 1;
	}

	if (bbt[ebcnt - 1])
	pr_info("skipping end of device tests because last "
	"block is bad\n");
	else {
	/* Attempt to write off end of device */
	ops.mode = MTD_OPS_AUTO_OOB;
	ops.len = 0;
	ops.retlen = 0;
	ops.ooblen = mtd->oobavail + 1;
	ops.oobretlen = 0;
	ops.ooboffs = 0;
	ops.datbuf = NULL;
	ops.oobbuf = writebuf;
	pr_info("attempting to write past end of device\n");
	pr_info("an error is expected...\n");
	err = mtd_write_oob(mtd, mtd->size - mtd->writesize, &ops);
	if (err) {
	pr_info("error occurred as expected\n");
	err = 0;
	} else {
	pr_err("error: wrote past end of device\n");
	errcnt += 1;
	}

	/* Attempt to read off end of device */
	ops.mode = MTD_OPS_AUTO_OOB;
	ops.len = 0;
	ops.retlen = 0;
	ops.ooblen = mtd->oobavail + 1;
	ops.oobretlen = 0;
	ops.ooboffs = 0;
	ops.datbuf = NULL;
	ops.oobbuf = readbuf;
	pr_info("attempting to read past end of device\n");
	pr_info("an error is expected...\n");
	err = mtd_read_oob(mtd, mtd->size - mtd->writesize, &ops);
	if (err) {
	pr_info("error occurred as expected\n");
	err = 0;
	} else {
	pr_err("error: read past end of device\n");
	errcnt += 1;
	}

	err = mtdtest_erase_eraseblock(mtd, ebcnt - 1);
	if (err)
	goto out;

	/* Attempt to write off end of device */
	ops.mode = MTD_OPS_AUTO_OOB;
	ops.len = 0;
	ops.retlen = 0;
	ops.ooblen = mtd->oobavail;
	ops.oobretlen = 0;
	ops.ooboffs = 1;
	ops.datbuf = NULL;
	ops.oobbuf = writebuf;
	pr_info("attempting to write past end of device\n");
	pr_info("an error is expected...\n");
	err = mtd_write_oob(mtd, mtd->size - mtd->writesize, &ops);
	if (err) {
	pr_info("error occurred as expected\n");
	err = 0;
	} else {
	pr_err("error: wrote past end of device\n");
	errcnt += 1;
	}

	/* Attempt to read off end of device */
	ops.mode = MTD_OPS_AUTO_OOB;
	ops.len = 0;
	ops.retlen = 0;
	ops.ooblen = mtd->oobavail;
	ops.oobretlen = 0;
	ops.ooboffs = 1;
	ops.datbuf = NULL;
	ops.oobbuf = readbuf;
	pr_info("attempting to read past end of device\n");
	pr_info("an error is expected...\n");
	err = mtd_read_oob(mtd, mtd->size - mtd->writesize, &ops);
	if (err) {
	pr_info("error occurred as expected\n");
	err = 0;
	} else {
	pr_err("error: read past end of device\n");
	errcnt += 1;
	}
	}

	/* Fifth test: write / read across block boundaries */
	pr_info("test 5 of 5\n");

	/* Erase all eraseblocks */
	err = mtdtest_erase_good_eraseblocks(mtd, bbt, 0, ebcnt);
	if (err)
	goto out;

	/* Write all eraseblocks */
	prandom_seed_state(&rnd_state, 11);
	pr_info("writing OOBs of whole device\n");
	for (i = 0; i < ebcnt - 1; ++i) {
	int cnt = 2;
	int pg;
	size_t sz = mtd->oobavail;
	if (bbt[i] \|\| bbt[i + 1])
	continue;
	addr = (loff_t)(i + 1) * mtd->erasesize - mtd->writesize;
	prandom_bytes_state(&rnd_state, writebuf, sz * cnt);
	for (pg = 0; pg < cnt; ++pg) {
	ops.mode = MTD_OPS_AUTO_OOB;
	ops.len = 0;
	ops.retlen = 0;
	ops.ooblen = sz;
	ops.oobretlen = 0;
	ops.ooboffs = 0;
	ops.datbuf = NULL;
	ops.oobbuf = writebuf + pg * sz;
	err = mtd_write_oob(mtd, addr, &ops);
	if (err)
	goto out;
	if (i % 256 == 0)
	pr_info("written up to eraseblock %u\n", i);

	err = mtdtest_relax();
	if (err)
	goto out;

	addr += mtd->writesize;
	}
	}
	pr_info("written %u eraseblocks\n", i);

	/* Check all eraseblocks */
	prandom_seed_state(&rnd_state, 11);
	pr_info("verifying all eraseblocks\n");
	for (i = 0; i < ebcnt - 1; ++i) {
	if (bbt[i] \|\| bbt[i + 1])
	continue;
	prandom_bytes_state(&rnd_state, writebuf, mtd->oobavail * 2);
	addr = (loff_t)(i + 1) * mtd->erasesize - mtd->writesize;
	ops.mode = MTD_OPS_AUTO_OOB;
	ops.len = 0;
	ops.retlen = 0;
	ops.ooblen = mtd->oobavail * 2;
	ops.oobretlen = 0;
	ops.ooboffs = 0;
	ops.datbuf = NULL;
	ops.oobbuf = readbuf;
	err = mtd_read_oob(mtd, addr, &ops);
	if (err)
	goto out;
	if (memcmpshow(addr, readbuf, writebuf,
	mtd->oobavail * 2)) {
	pr_err("error: verify failed at %#llx\n",
	(long long)addr);
	errcnt += 1;
	if (errcnt > 1000) {
	pr_err("error: too many errors\n");
	goto out;
	}
	}
	if (i % 256 == 0)
	pr_info("verified up to eraseblock %u\n", i);

	err = mtdtest_relax();
	if (err)
	goto out;
	}
	pr_info("verified %u eraseblocks\n", i);

	pr_info("finished with %d errors\n", errcnt);
	out:
	kfree(bbt);
	kfree(writebuf);
	kfree(readbuf);
	put_mtd_device(mtd);
	if (err)
	pr_info("error %d occurred\n", err);
	printk(KERN_INFO "=================================================\n");
	return err;
	}
	module_init(mtd_oobtest_init);

	static void __exit mtd_oobtest_exit(void)
	{
	return;
	}
	module_exit(mtd_oobtest_exit);

	MODULE_DESCRIPTION("Out-of-band test module");
	MODULE_AUTHOR("Adrian Hunter");
	MODULE_LICENSE("GPL");