drivers/mtd/tests/mtd_pagetest.c - kernel/msm-4.9 - Gitiles

 /*
  * 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 page 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>

 static int dev = -EINVAL;
 module_param(dev, int, S_IRUGO);
 MODULE_PARM_DESC(dev, "MTD device number to use");

 static struct mtd_info *mtd;
 static unsigned char *twopages;
 static unsigned char *writebuf;
 static unsigned char *boundary;
 static unsigned char *bbt;

 static int pgsize;
 static int bufsize;
 static int ebcnt;
 static int pgcnt;
 static int errcnt;
 static unsigned long next = 1;

 static inline unsigned int simple_rand(void)
 {
 	next = next * 1103515245 + 12345;
 	return (unsigned int)((next / 65536) % 32768);
 }

 static inline void simple_srand(unsigned long seed)
 {
 	next = seed;
 }

 static void set_random_data(unsigned char *buf, size_t len)
 {
 	size_t i;

 	for (i = 0; i < len; ++i)
 		buf[i] = simple_rand();
 }

 static int erase_eraseblock(int ebnum)
 {
 	int err;
 	struct erase_info ei;
 	loff_t addr = ebnum * mtd->erasesize;

 	memset(&ei, 0, sizeof(struct erase_info));
 	ei.mtd  = mtd;
 	ei.addr = addr;
 	ei.len  = mtd->erasesize;

 	err = mtd_erase(mtd, &ei);
 	if (err) {
 		pr_err("error %d while erasing EB %d\n", err, ebnum);
 		return err;
 	}

 	if (ei.state == MTD_ERASE_FAILED) {
 		pr_err("some erase error occurred at EB %d\n",
 		       ebnum);
 		return -EIO;
 	}

 	return 0;
 }

 static int write_eraseblock(int ebnum)
 {
 	int err = 0;
 	size_t written;
 	loff_t addr = ebnum * mtd->erasesize;

 	set_random_data(writebuf, mtd->erasesize);
 	cond_resched();
 	err = mtd_write(mtd, addr, mtd->erasesize, &written, writebuf);
 	if (err || written != mtd->erasesize)
 		pr_err("error: write failed at %#llx\n",
 		       (long long)addr);

 	return err;
 }

 static int verify_eraseblock(int ebnum)
 {
 	uint32_t j;
 	size_t read;
 	int err = 0, i;
 	loff_t addr0, addrn;
 	loff_t addr = ebnum * mtd->erasesize;

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

 	addrn = mtd->size;
 	for (i = 0; i < ebcnt && bbt[ebcnt - i - 1]; ++i)
 		addrn -= mtd->erasesize;

 	set_random_data(writebuf, mtd->erasesize);
 	for (j = 0; j < pgcnt - 1; ++j, addr += pgsize) {
 		/* Do a read to set the internal dataRAMs to different data */
 		err = mtd_read(mtd, addr0, bufsize, &read, twopages);
 		if (mtd_is_bitflip(err))
 			err = 0;
 		if (err || read != bufsize) {
 			pr_err("error: read failed at %#llx\n",
 			       (long long)addr0);
 			return err;
 		}
 		err = mtd_read(mtd, addrn - bufsize, bufsize, &read, twopages);
 		if (mtd_is_bitflip(err))
 			err = 0;
 		if (err || read != bufsize) {
 			pr_err("error: read failed at %#llx\n",
 			       (long long)(addrn - bufsize));
 			return err;
 		}
 		memset(twopages, 0, bufsize);
 		err = mtd_read(mtd, addr, bufsize, &read, twopages);
 		if (mtd_is_bitflip(err))
 			err = 0;
 		if (err || read != bufsize) {
 			pr_err("error: read failed at %#llx\n",
 			       (long long)addr);
 			break;
 		}
 		if (memcmp(twopages, writebuf + (j * pgsize), bufsize)) {
 			pr_err("error: verify failed at %#llx\n",
 			       (long long)addr);
 			errcnt += 1;
 		}
 	}
 	/* Check boundary between eraseblocks */
 	if (addr <= addrn - pgsize - pgsize && !bbt[ebnum + 1]) {
 		unsigned long oldnext = next;
 		/* Do a read to set the internal dataRAMs to different data */
 		err = mtd_read(mtd, addr0, bufsize, &read, twopages);
 		if (mtd_is_bitflip(err))
 			err = 0;
 		if (err || read != bufsize) {
 			pr_err("error: read failed at %#llx\n",
 			       (long long)addr0);
 			return err;
 		}
 		err = mtd_read(mtd, addrn - bufsize, bufsize, &read, twopages);
 		if (mtd_is_bitflip(err))
 			err = 0;
 		if (err || read != bufsize) {
 			pr_err("error: read failed at %#llx\n",
 			       (long long)(addrn - bufsize));
 			return err;
 		}
 		memset(twopages, 0, bufsize);
 		err = mtd_read(mtd, addr, bufsize, &read, twopages);
 		if (mtd_is_bitflip(err))
 			err = 0;
 		if (err || read != bufsize) {
 			pr_err("error: read failed at %#llx\n",
 			       (long long)addr);
 			return err;
 		}
 		memcpy(boundary, writebuf + mtd->erasesize - pgsize, pgsize);
 		set_random_data(boundary + pgsize, pgsize);
 		if (memcmp(twopages, boundary, bufsize)) {
 			pr_err("error: verify failed at %#llx\n",
 			       (long long)addr);
 			errcnt += 1;
 		}
 		next = oldnext;
 	}
 	return err;
 }

 static int crosstest(void)
 {
 	size_t read;
 	int err = 0, i;
 	loff_t addr, addr0, addrn;
 	unsigned char *pp1, *pp2, *pp3, *pp4;

 	pr_info("crosstest\n");
 	pp1 = kmalloc(pgsize * 4, GFP_KERNEL);
 	if (!pp1) {
 		pr_err("error: cannot allocate memory\n");
 		return -ENOMEM;
 	}
 	pp2 = pp1 + pgsize;
 	pp3 = pp2 + pgsize;
 	pp4 = pp3 + pgsize;
 	memset(pp1, 0, pgsize * 4);

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

 	addrn = mtd->size;
 	for (i = 0; i < ebcnt && bbt[ebcnt - i - 1]; ++i)
 		addrn -= mtd->erasesize;

 	/* Read 2nd-to-last page to pp1 */
 	addr = addrn - pgsize - pgsize;
 	err = mtd_read(mtd, addr, pgsize, &read, pp1);
 	if (mtd_is_bitflip(err))
 		err = 0;
 	if (err || read != pgsize) {
 		pr_err("error: read failed at %#llx\n",
 		       (long long)addr);
 		kfree(pp1);
 		return err;
 	}

 	/* Read 3rd-to-last page to pp1 */
 	addr = addrn - pgsize - pgsize - pgsize;
 	err = mtd_read(mtd, addr, pgsize, &read, pp1);
 	if (mtd_is_bitflip(err))
 		err = 0;
 	if (err || read != pgsize) {
 		pr_err("error: read failed at %#llx\n",
 		       (long long)addr);
 		kfree(pp1);
 		return err;
 	}

 	/* Read first page to pp2 */
 	addr = addr0;
 	pr_info("reading page at %#llx\n", (long long)addr);
 	err = mtd_read(mtd, addr, pgsize, &read, pp2);
 	if (mtd_is_bitflip(err))
 		err = 0;
 	if (err || read != pgsize) {
 		pr_err("error: read failed at %#llx\n",
 		       (long long)addr);
 		kfree(pp1);
 		return err;
 	}

 	/* Read last page to pp3 */
 	addr = addrn - pgsize;
 	pr_info("reading page at %#llx\n", (long long)addr);
 	err = mtd_read(mtd, addr, pgsize, &read, pp3);
 	if (mtd_is_bitflip(err))
 		err = 0;
 	if (err || read != pgsize) {
 		pr_err("error: read failed at %#llx\n",
 		       (long long)addr);
 		kfree(pp1);
 		return err;
 	}

 	/* Read first page again to pp4 */
 	addr = addr0;
 	pr_info("reading page at %#llx\n", (long long)addr);
 	err = mtd_read(mtd, addr, pgsize, &read, pp4);
 	if (mtd_is_bitflip(err))
 		err = 0;
 	if (err || read != pgsize) {
 		pr_err("error: read failed at %#llx\n",
 		       (long long)addr);
 		kfree(pp1);
 		return err;
 	}

 	/* pp2 and pp4 should be the same */
 	pr_info("verifying pages read at %#llx match\n",
 	       (long long)addr0);
 	if (memcmp(pp2, pp4, pgsize)) {
 		pr_err("verify failed!\n");
 		errcnt += 1;
 	} else if (!err)
 		pr_info("crosstest ok\n");
 	kfree(pp1);
 	return err;
 }

 static int erasecrosstest(void)
 {
 	size_t read, written;
 	int err = 0, i, ebnum, ebnum2;
 	loff_t addr0;
 	char *readbuf = twopages;

 	pr_info("erasecrosstest\n");

 	ebnum = 0;
 	addr0 = 0;
 	for (i = 0; i < ebcnt && bbt[i]; ++i) {
 		addr0 += mtd->erasesize;
 		ebnum += 1;
 	}

 	ebnum2 = ebcnt - 1;
 	while (ebnum2 && bbt[ebnum2])
 		ebnum2 -= 1;

 	pr_info("erasing block %d\n", ebnum);
 	err = erase_eraseblock(ebnum);
 	if (err)
 		return err;

 	pr_info("writing 1st page of block %d\n", ebnum);
 	set_random_data(writebuf, pgsize);
 	strcpy(writebuf, "There is no data like this!");
 	err = mtd_write(mtd, addr0, pgsize, &written, writebuf);
 	if (err || written != pgsize) {
 		pr_info("error: write failed at %#llx\n",
 		       (long long)addr0);
 		return err ? err : -1;
 	}

 	pr_info("reading 1st page of block %d\n", ebnum);
 	memset(readbuf, 0, pgsize);
 	err = mtd_read(mtd, addr0, pgsize, &read, readbuf);
 	if (mtd_is_bitflip(err))
 		err = 0;
 	if (err || read != pgsize) {
 		pr_err("error: read failed at %#llx\n",
 		       (long long)addr0);
 		return err ? err : -1;
 	}

 	pr_info("verifying 1st page of block %d\n", ebnum);
 	if (memcmp(writebuf, readbuf, pgsize)) {
 		pr_err("verify failed!\n");
 		errcnt += 1;
 		return -1;
 	}

 	pr_info("erasing block %d\n", ebnum);
 	err = erase_eraseblock(ebnum);
 	if (err)
 		return err;

 	pr_info("writing 1st page of block %d\n", ebnum);
 	set_random_data(writebuf, pgsize);
 	strcpy(writebuf, "There is no data like this!");
 	err = mtd_write(mtd, addr0, pgsize, &written, writebuf);
 	if (err || written != pgsize) {
 		pr_err("error: write failed at %#llx\n",
 		       (long long)addr0);
 		return err ? err : -1;
 	}

 	pr_info("erasing block %d\n", ebnum2);
 	err = erase_eraseblock(ebnum2);
 	if (err)
 		return err;

 	pr_info("reading 1st page of block %d\n", ebnum);
 	memset(readbuf, 0, pgsize);
 	err = mtd_read(mtd, addr0, pgsize, &read, readbuf);
 	if (mtd_is_bitflip(err))
 		err = 0;
 	if (err || read != pgsize) {
 		pr_err("error: read failed at %#llx\n",
 		       (long long)addr0);
 		return err ? err : -1;
 	}

 	pr_info("verifying 1st page of block %d\n", ebnum);
 	if (memcmp(writebuf, readbuf, pgsize)) {
 		pr_err("verify failed!\n");
 		errcnt += 1;
 		return -1;
 	}

 	if (!err)
 		pr_info("erasecrosstest ok\n");
 	return err;
 }

 static int erasetest(void)
 {
 	size_t read, written;
 	int err = 0, i, ebnum, ok = 1;
 	loff_t addr0;

 	pr_info("erasetest\n");

 	ebnum = 0;
 	addr0 = 0;
 	for (i = 0; i < ebcnt && bbt[i]; ++i) {
 		addr0 += mtd->erasesize;
 		ebnum += 1;
 	}

 	pr_info("erasing block %d\n", ebnum);
 	err = erase_eraseblock(ebnum);
 	if (err)
 		return err;

 	pr_info("writing 1st page of block %d\n", ebnum);
 	set_random_data(writebuf, pgsize);
 	err = mtd_write(mtd, addr0, pgsize, &written, writebuf);
 	if (err || written != pgsize) {
 		pr_err("error: write failed at %#llx\n",
 		       (long long)addr0);
 		return err ? err : -1;
 	}

 	pr_info("erasing block %d\n", ebnum);
 	err = erase_eraseblock(ebnum);
 	if (err)
 		return err;

 	pr_info("reading 1st page of block %d\n", ebnum);
 	err = mtd_read(mtd, addr0, pgsize, &read, twopages);
 	if (mtd_is_bitflip(err))
 		err = 0;
 	if (err || read != pgsize) {
 		pr_err("error: read failed at %#llx\n",
 		       (long long)addr0);
 		return err ? err : -1;
 	}

 	pr_info("verifying 1st page of block %d is all 0xff\n",
 	       ebnum);
 	for (i = 0; i < pgsize; ++i)
 		if (twopages[i] != 0xff) {
 			pr_err("verifying all 0xff failed at %d\n",
 			       i);
 			errcnt += 1;
 			ok = 0;
 			break;
 		}

 	if (ok && !err)
 		pr_info("erasetest ok\n");

 	return err;
 }

 static int is_block_bad(int ebnum)
 {
 	loff_t addr = ebnum * mtd->erasesize;
 	int ret;

 	ret = mtd_block_isbad(mtd, addr);
 	if (ret)
 		pr_info("block %d is bad\n", ebnum);
 	return ret;
 }

 static int scan_for_bad_eraseblocks(void)
 {
 	int i, bad = 0;

 	bbt = kzalloc(ebcnt, GFP_KERNEL);
 	if (!bbt) {
 		pr_err("error: cannot allocate memory\n");
 		return -ENOMEM;
 	}

 	pr_info("scanning for bad eraseblocks\n");
 	for (i = 0; i < ebcnt; ++i) {
 		bbt[i] = is_block_bad(i) ? 1 : 0;
 		if (bbt[i])
 			bad += 1;
 		cond_resched();
 	}
 	pr_info("scanned %d eraseblocks, %d are bad\n", i, bad);
 	return 0;
 }

 static int __init mtd_pagetest_init(void)
 {
 	int err = 0;
 	uint64_t tmp;
 	uint32_t i;

 	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 != MTD_NANDFLASH) {
 		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;
 	pgsize = 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,
 	       pgsize, ebcnt, pgcnt, mtd->oobsize);

 	err = -ENOMEM;
 	bufsize = pgsize * 2;
 	writebuf = kmalloc(mtd->erasesize, GFP_KERNEL);
 	if (!writebuf) {
 		pr_err("error: cannot allocate memory\n");
 		goto out;
 	}
 	twopages = kmalloc(bufsize, GFP_KERNEL);
 	if (!twopages) {
 		pr_err("error: cannot allocate memory\n");
 		goto out;
 	}
 	boundary = kmalloc(bufsize, GFP_KERNEL);
 	if (!boundary) {
 		pr_err("error: cannot allocate memory\n");
 		goto out;
 	}

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

 	/* Erase all eraseblocks */
 	pr_info("erasing whole device\n");
 	for (i = 0; i < ebcnt; ++i) {
 		if (bbt[i])
 			continue;
 		err = erase_eraseblock(i);
 		if (err)
 			goto out;
 		cond_resched();
 	}
 	pr_info("erased %u eraseblocks\n", i);

 	/* Write all eraseblocks */
 	simple_srand(1);
 	pr_info("writing whole device\n");
 	for (i = 0; i < ebcnt; ++i) {
 		if (bbt[i])
 			continue;
 		err = write_eraseblock(i);
 		if (err)
 			goto out;
 		if (i % 256 == 0)
 			pr_info("written up to eraseblock %u\n", i);
 		cond_resched();
 	}
 	pr_info("written %u eraseblocks\n", i);

 	/* Check all eraseblocks */
 	simple_srand(1);
 	pr_info("verifying all eraseblocks\n");
 	for (i = 0; i < ebcnt; ++i) {
 		if (bbt[i])
 			continue;
 		err = verify_eraseblock(i);
 		if (err)
 			goto out;
 		if (i % 256 == 0)
 			pr_info("verified up to eraseblock %u\n", i);
 		cond_resched();
 	}
 	pr_info("verified %u eraseblocks\n", i);

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

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

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

 	pr_info("finished with %d errors\n", errcnt);
 out:

 	kfree(bbt);
 	kfree(boundary);
 	kfree(twopages);
 	kfree(writebuf);
 	put_mtd_device(mtd);
 	if (err)
 		pr_info("error %d occurred\n", err);
 	printk(KERN_INFO "=================================================\n");
 	return err;
 }
 module_init(mtd_pagetest_init);

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

 MODULE_DESCRIPTION("NAND page test");
 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 page 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>

	static int dev = -EINVAL;
	module_param(dev, int, S_IRUGO);
	MODULE_PARM_DESC(dev, "MTD device number to use");

	static struct mtd_info *mtd;
	static unsigned char *twopages;
	static unsigned char *writebuf;
	static unsigned char *boundary;
	static unsigned char *bbt;

	static int pgsize;
	static int bufsize;
	static int ebcnt;
	static int pgcnt;
	static int errcnt;
	static unsigned long next = 1;

	static inline unsigned int simple_rand(void)
	{
	next = next * 1103515245 + 12345;
	return (unsigned int)((next / 65536) % 32768);
	}

	static inline void simple_srand(unsigned long seed)
	{
	next = seed;
	}

	static void set_random_data(unsigned char *buf, size_t len)
	{
	size_t i;

	for (i = 0; i < len; ++i)
	buf[i] = simple_rand();
	}

	static int erase_eraseblock(int ebnum)
	{
	int err;
	struct erase_info ei;
	loff_t addr = ebnum * mtd->erasesize;

	memset(&ei, 0, sizeof(struct erase_info));
	ei.mtd = mtd;
	ei.addr = addr;
	ei.len = mtd->erasesize;

	err = mtd_erase(mtd, &ei);
	if (err) {
	pr_err("error %d while erasing EB %d\n", err, ebnum);
	return err;
	}

	if (ei.state == MTD_ERASE_FAILED) {
	pr_err("some erase error occurred at EB %d\n",
	ebnum);
	return -EIO;
	}

	return 0;
	}

	static int write_eraseblock(int ebnum)
	{
	int err = 0;
	size_t written;
	loff_t addr = ebnum * mtd->erasesize;

	set_random_data(writebuf, mtd->erasesize);
	cond_resched();
	err = mtd_write(mtd, addr, mtd->erasesize, &written, writebuf);
	if (err \|\| written != mtd->erasesize)
	pr_err("error: write failed at %#llx\n",
	(long long)addr);

	return err;
	}

	static int verify_eraseblock(int ebnum)
	{
	uint32_t j;
	size_t read;
	int err = 0, i;
	loff_t addr0, addrn;
	loff_t addr = ebnum * mtd->erasesize;

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

	addrn = mtd->size;
	for (i = 0; i < ebcnt && bbt[ebcnt - i - 1]; ++i)
	addrn -= mtd->erasesize;

	set_random_data(writebuf, mtd->erasesize);
	for (j = 0; j < pgcnt - 1; ++j, addr += pgsize) {
	/* Do a read to set the internal dataRAMs to different data */
	err = mtd_read(mtd, addr0, bufsize, &read, twopages);
	if (mtd_is_bitflip(err))
	err = 0;
	if (err \|\| read != bufsize) {
	pr_err("error: read failed at %#llx\n",
	(long long)addr0);
	return err;
	}
	err = mtd_read(mtd, addrn - bufsize, bufsize, &read, twopages);
	if (mtd_is_bitflip(err))
	err = 0;
	if (err \|\| read != bufsize) {
	pr_err("error: read failed at %#llx\n",
	(long long)(addrn - bufsize));
	return err;
	}
	memset(twopages, 0, bufsize);
	err = mtd_read(mtd, addr, bufsize, &read, twopages);
	if (mtd_is_bitflip(err))
	err = 0;
	if (err \|\| read != bufsize) {
	pr_err("error: read failed at %#llx\n",
	(long long)addr);
	break;
	}
	if (memcmp(twopages, writebuf + (j * pgsize), bufsize)) {
	pr_err("error: verify failed at %#llx\n",
	(long long)addr);
	errcnt += 1;
	}
	}
	/* Check boundary between eraseblocks */
	if (addr <= addrn - pgsize - pgsize && !bbt[ebnum + 1]) {
	unsigned long oldnext = next;
	/* Do a read to set the internal dataRAMs to different data */
	err = mtd_read(mtd, addr0, bufsize, &read, twopages);
	if (mtd_is_bitflip(err))
	err = 0;
	if (err \|\| read != bufsize) {
	pr_err("error: read failed at %#llx\n",
	(long long)addr0);
	return err;
	}
	err = mtd_read(mtd, addrn - bufsize, bufsize, &read, twopages);
	if (mtd_is_bitflip(err))
	err = 0;
	if (err \|\| read != bufsize) {
	pr_err("error: read failed at %#llx\n",
	(long long)(addrn - bufsize));
	return err;
	}
	memset(twopages, 0, bufsize);
	err = mtd_read(mtd, addr, bufsize, &read, twopages);
	if (mtd_is_bitflip(err))
	err = 0;
	if (err \|\| read != bufsize) {
	pr_err("error: read failed at %#llx\n",
	(long long)addr);
	return err;
	}
	memcpy(boundary, writebuf + mtd->erasesize - pgsize, pgsize);
	set_random_data(boundary + pgsize, pgsize);
	if (memcmp(twopages, boundary, bufsize)) {
	pr_err("error: verify failed at %#llx\n",
	(long long)addr);
	errcnt += 1;
	}
	next = oldnext;
	}
	return err;
	}

	static int crosstest(void)
	{
	size_t read;
	int err = 0, i;
	loff_t addr, addr0, addrn;
	unsigned char pp1, pp2, pp3, pp4;

	pr_info("crosstest\n");
	pp1 = kmalloc(pgsize * 4, GFP_KERNEL);
	if (!pp1) {
	pr_err("error: cannot allocate memory\n");
	return -ENOMEM;
	}
	pp2 = pp1 + pgsize;
	pp3 = pp2 + pgsize;
	pp4 = pp3 + pgsize;
	memset(pp1, 0, pgsize * 4);

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

	addrn = mtd->size;
	for (i = 0; i < ebcnt && bbt[ebcnt - i - 1]; ++i)
	addrn -= mtd->erasesize;

	/* Read 2nd-to-last page to pp1 */
	addr = addrn - pgsize - pgsize;
	err = mtd_read(mtd, addr, pgsize, &read, pp1);
	if (mtd_is_bitflip(err))
	err = 0;
	if (err \|\| read != pgsize) {
	pr_err("error: read failed at %#llx\n",
	(long long)addr);
	kfree(pp1);
	return err;
	}

	/* Read 3rd-to-last page to pp1 */
	addr = addrn - pgsize - pgsize - pgsize;
	err = mtd_read(mtd, addr, pgsize, &read, pp1);
	if (mtd_is_bitflip(err))
	err = 0;
	if (err \|\| read != pgsize) {
	pr_err("error: read failed at %#llx\n",
	(long long)addr);
	kfree(pp1);
	return err;
	}

	/* Read first page to pp2 */
	addr = addr0;
	pr_info("reading page at %#llx\n", (long long)addr);
	err = mtd_read(mtd, addr, pgsize, &read, pp2);
	if (mtd_is_bitflip(err))
	err = 0;
	if (err \|\| read != pgsize) {
	pr_err("error: read failed at %#llx\n",
	(long long)addr);
	kfree(pp1);
	return err;
	}

	/* Read last page to pp3 */
	addr = addrn - pgsize;
	pr_info("reading page at %#llx\n", (long long)addr);
	err = mtd_read(mtd, addr, pgsize, &read, pp3);
	if (mtd_is_bitflip(err))
	err = 0;
	if (err \|\| read != pgsize) {
	pr_err("error: read failed at %#llx\n",
	(long long)addr);
	kfree(pp1);
	return err;
	}

	/* Read first page again to pp4 */
	addr = addr0;
	pr_info("reading page at %#llx\n", (long long)addr);
	err = mtd_read(mtd, addr, pgsize, &read, pp4);
	if (mtd_is_bitflip(err))
	err = 0;
	if (err \|\| read != pgsize) {
	pr_err("error: read failed at %#llx\n",
	(long long)addr);
	kfree(pp1);
	return err;
	}

	/* pp2 and pp4 should be the same */
	pr_info("verifying pages read at %#llx match\n",
	(long long)addr0);
	if (memcmp(pp2, pp4, pgsize)) {
	pr_err("verify failed!\n");
	errcnt += 1;
	} else if (!err)
	pr_info("crosstest ok\n");
	kfree(pp1);
	return err;
	}

	static int erasecrosstest(void)
	{
	size_t read, written;
	int err = 0, i, ebnum, ebnum2;
	loff_t addr0;
	char *readbuf = twopages;

	pr_info("erasecrosstest\n");

	ebnum = 0;
	addr0 = 0;
	for (i = 0; i < ebcnt && bbt[i]; ++i) {
	addr0 += mtd->erasesize;
	ebnum += 1;
	}

	ebnum2 = ebcnt - 1;
	while (ebnum2 && bbt[ebnum2])
	ebnum2 -= 1;

	pr_info("erasing block %d\n", ebnum);
	err = erase_eraseblock(ebnum);
	if (err)
	return err;

	pr_info("writing 1st page of block %d\n", ebnum);
	set_random_data(writebuf, pgsize);
	strcpy(writebuf, "There is no data like this!");
	err = mtd_write(mtd, addr0, pgsize, &written, writebuf);
	if (err \|\| written != pgsize) {
	pr_info("error: write failed at %#llx\n",
	(long long)addr0);
	return err ? err : -1;
	}

	pr_info("reading 1st page of block %d\n", ebnum);
	memset(readbuf, 0, pgsize);
	err = mtd_read(mtd, addr0, pgsize, &read, readbuf);
	if (mtd_is_bitflip(err))
	err = 0;
	if (err \|\| read != pgsize) {
	pr_err("error: read failed at %#llx\n",
	(long long)addr0);
	return err ? err : -1;
	}

	pr_info("verifying 1st page of block %d\n", ebnum);
	if (memcmp(writebuf, readbuf, pgsize)) {
	pr_err("verify failed!\n");
	errcnt += 1;
	return -1;
	}

	pr_info("erasing block %d\n", ebnum);
	err = erase_eraseblock(ebnum);
	if (err)
	return err;

	pr_info("writing 1st page of block %d\n", ebnum);
	set_random_data(writebuf, pgsize);
	strcpy(writebuf, "There is no data like this!");
	err = mtd_write(mtd, addr0, pgsize, &written, writebuf);
	if (err \|\| written != pgsize) {
	pr_err("error: write failed at %#llx\n",
	(long long)addr0);
	return err ? err : -1;
	}

	pr_info("erasing block %d\n", ebnum2);
	err = erase_eraseblock(ebnum2);
	if (err)
	return err;

	pr_info("reading 1st page of block %d\n", ebnum);
	memset(readbuf, 0, pgsize);
	err = mtd_read(mtd, addr0, pgsize, &read, readbuf);
	if (mtd_is_bitflip(err))
	err = 0;
	if (err \|\| read != pgsize) {
	pr_err("error: read failed at %#llx\n",
	(long long)addr0);
	return err ? err : -1;
	}

	pr_info("verifying 1st page of block %d\n", ebnum);
	if (memcmp(writebuf, readbuf, pgsize)) {
	pr_err("verify failed!\n");
	errcnt += 1;
	return -1;
	}

	if (!err)
	pr_info("erasecrosstest ok\n");
	return err;
	}

	static int erasetest(void)
	{
	size_t read, written;
	int err = 0, i, ebnum, ok = 1;
	loff_t addr0;

	pr_info("erasetest\n");

	ebnum = 0;
	addr0 = 0;
	for (i = 0; i < ebcnt && bbt[i]; ++i) {
	addr0 += mtd->erasesize;
	ebnum += 1;
	}

	pr_info("erasing block %d\n", ebnum);
	err = erase_eraseblock(ebnum);
	if (err)
	return err;

	pr_info("writing 1st page of block %d\n", ebnum);
	set_random_data(writebuf, pgsize);
	err = mtd_write(mtd, addr0, pgsize, &written, writebuf);
	if (err \|\| written != pgsize) {
	pr_err("error: write failed at %#llx\n",
	(long long)addr0);
	return err ? err : -1;
	}

	pr_info("erasing block %d\n", ebnum);
	err = erase_eraseblock(ebnum);
	if (err)
	return err;

	pr_info("reading 1st page of block %d\n", ebnum);
	err = mtd_read(mtd, addr0, pgsize, &read, twopages);
	if (mtd_is_bitflip(err))
	err = 0;
	if (err \|\| read != pgsize) {
	pr_err("error: read failed at %#llx\n",
	(long long)addr0);
	return err ? err : -1;
	}

	pr_info("verifying 1st page of block %d is all 0xff\n",
	ebnum);
	for (i = 0; i < pgsize; ++i)
	if (twopages[i] != 0xff) {
	pr_err("verifying all 0xff failed at %d\n",
	i);
	errcnt += 1;
	ok = 0;
	break;
	}

	if (ok && !err)
	pr_info("erasetest ok\n");

	return err;
	}

	static int is_block_bad(int ebnum)
	{
	loff_t addr = ebnum * mtd->erasesize;
	int ret;

	ret = mtd_block_isbad(mtd, addr);
	if (ret)
	pr_info("block %d is bad\n", ebnum);
	return ret;
	}

	static int scan_for_bad_eraseblocks(void)
	{
	int i, bad = 0;

	bbt = kzalloc(ebcnt, GFP_KERNEL);
	if (!bbt) {
	pr_err("error: cannot allocate memory\n");
	return -ENOMEM;
	}

	pr_info("scanning for bad eraseblocks\n");
	for (i = 0; i < ebcnt; ++i) {
	bbt[i] = is_block_bad(i) ? 1 : 0;
	if (bbt[i])
	bad += 1;
	cond_resched();
	}
	pr_info("scanned %d eraseblocks, %d are bad\n", i, bad);
	return 0;
	}

	static int __init mtd_pagetest_init(void)
	{
	int err = 0;
	uint64_t tmp;
	uint32_t i;

	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 != MTD_NANDFLASH) {
	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;
	pgsize = 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,
	pgsize, ebcnt, pgcnt, mtd->oobsize);

	err = -ENOMEM;
	bufsize = pgsize * 2;
	writebuf = kmalloc(mtd->erasesize, GFP_KERNEL);
	if (!writebuf) {
	pr_err("error: cannot allocate memory\n");
	goto out;
	}
	twopages = kmalloc(bufsize, GFP_KERNEL);
	if (!twopages) {
	pr_err("error: cannot allocate memory\n");
	goto out;
	}
	boundary = kmalloc(bufsize, GFP_KERNEL);
	if (!boundary) {
	pr_err("error: cannot allocate memory\n");
	goto out;
	}

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

	/* Erase all eraseblocks */
	pr_info("erasing whole device\n");
	for (i = 0; i < ebcnt; ++i) {
	if (bbt[i])
	continue;
	err = erase_eraseblock(i);
	if (err)
	goto out;
	cond_resched();
	}
	pr_info("erased %u eraseblocks\n", i);

	/* Write all eraseblocks */
	simple_srand(1);
	pr_info("writing whole device\n");
	for (i = 0; i < ebcnt; ++i) {
	if (bbt[i])
	continue;
	err = write_eraseblock(i);
	if (err)
	goto out;
	if (i % 256 == 0)
	pr_info("written up to eraseblock %u\n", i);
	cond_resched();
	}
	pr_info("written %u eraseblocks\n", i);

	/* Check all eraseblocks */
	simple_srand(1);
	pr_info("verifying all eraseblocks\n");
	for (i = 0; i < ebcnt; ++i) {
	if (bbt[i])
	continue;
	err = verify_eraseblock(i);
	if (err)
	goto out;
	if (i % 256 == 0)
	pr_info("verified up to eraseblock %u\n", i);
	cond_resched();
	}
	pr_info("verified %u eraseblocks\n", i);

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

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

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

	pr_info("finished with %d errors\n", errcnt);
	out:

	kfree(bbt);
	kfree(boundary);
	kfree(twopages);
	kfree(writebuf);
	put_mtd_device(mtd);
	if (err)
	pr_info("error %d occurred\n", err);
	printk(KERN_INFO "=================================================\n");
	return err;
	}
	module_init(mtd_pagetest_init);

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

	MODULE_DESCRIPTION("NAND page test");
	MODULE_AUTHOR("Adrian Hunter");
	MODULE_LICENSE("GPL");