[mirror_ubuntu-focal-kernel.git] / drivers / mtd / tests / nandbiterrs.c

// SPDX-License-Identifier: GPL-2.0-only
/*
 * Copyright © 2012 NetCommWireless
 * Iwo Mergler <Iwo.Mergler@netcommwireless.com.au>
 *
 * Test for multi-bit error recovery on a NAND page This mostly tests the
 * ECC controller / driver.
 *
 * There are two test modes:
 *
 *	0 - artificially inserting bit errors until the ECC fails
 *	    This is the default method and fairly quick. It should
 *	    be independent of the quality of the FLASH.
 *
 *	1 - re-writing the same pattern repeatedly until the ECC fails.
 *	    This method relies on the physics of NAND FLASH to eventually
 *	    generate '0' bits if '1' has been written sufficient times.
 *	    Depending on the NAND, the first bit errors will appear after
 *	    1000 or more writes and then will usually snowball, reaching the
 *	    limits of the ECC quickly.
 *
 *	    The test stops after 10000 cycles, should your FLASH be
 *	    exceptionally good and not generate bit errors before that. Try
 *	    a different page in that case.
 *
 * Please note that neither of these tests will significantly 'use up' any
 * FLASH endurance. Only a maximum of two erase operations will be performed.
 */

#define pr_fmt(fmt)	KBUILD_MODNAME ": " fmt

#include <linux/init.h>
#include <linux/module.h>
#include <linux/moduleparam.h>
#include <linux/mtd/mtd.h>
#include <linux/err.h>
#include <linux/mtd/rawnand.h>
#include <linux/slab.h>
#include "mtd_test.h"

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

static unsigned page_offset;
module_param(page_offset, uint, S_IRUGO);
MODULE_PARM_DESC(page_offset, "Page number relative to dev start");

static unsigned seed;
module_param(seed, uint, S_IRUGO);
MODULE_PARM_DESC(seed, "Random seed");

static int mode;
module_param(mode, int, S_IRUGO);
MODULE_PARM_DESC(mode, "0=incremental errors, 1=overwrite test");

static unsigned max_overwrite = 10000;

static loff_t   offset;     /* Offset of the page we're using. */
static unsigned eraseblock; /* Eraseblock number for our page. */

/* We assume that the ECC can correct up to a certain number
 * of biterrors per subpage. */
static unsigned subsize;  /* Size of subpages */
static unsigned subcount; /* Number of subpages per page */

static struct mtd_info *mtd;   /* MTD device */

static uint8_t *wbuffer; /* One page write / compare buffer */
static uint8_t *rbuffer; /* One page read buffer */

/* 'random' bytes from known offsets */
static uint8_t hash(unsigned offset)
{
	unsigned v = offset;
	unsigned char c;
	v ^= 0x7f7edfd3;
	v = v ^ (v >> 3);
	v = v ^ (v >> 5);
	v = v ^ (v >> 13);
	c = v & 0xFF;
	/* Reverse bits of result. */
	c = (c & 0x0F) << 4 | (c & 0xF0) >> 4;
	c = (c & 0x33) << 2 | (c & 0xCC) >> 2;
	c = (c & 0x55) << 1 | (c & 0xAA) >> 1;
	return c;
}

/* Writes wbuffer to page */
static int write_page(int log)
{
	if (log)
		pr_info("write_page\n");

	return mtdtest_write(mtd, offset, mtd->writesize, wbuffer);
}

/* Re-writes the data area while leaving the OOB alone. */
static int rewrite_page(int log)
{
	int err = 0;
	struct mtd_oob_ops ops;

	if (log)
		pr_info("rewrite page\n");

	ops.mode      = MTD_OPS_RAW; /* No ECC */
	ops.len       = mtd->writesize;
	ops.retlen    = 0;
	ops.ooblen    = 0;
	ops.oobretlen = 0;
	ops.ooboffs   = 0;
	ops.datbuf    = wbuffer;
	ops.oobbuf    = NULL;

	err = mtd_write_oob(mtd, offset, &ops);
	if (err || ops.retlen != mtd->writesize) {
		pr_err("error: write_oob failed (%d)\n", err);
		if (!err)
			err = -EIO;
	}

	return err;
}

/* Reads page into rbuffer. Returns number of corrected bit errors (>=0)
 * or error (<0) */
static int read_page(int log)
{
	int err = 0;
	size_t read;
	struct mtd_ecc_stats oldstats;

	if (log)
		pr_info("read_page\n");

	/* Saving last mtd stats */
	memcpy(&oldstats, &mtd->ecc_stats, sizeof(oldstats));

	err = mtd_read(mtd, offset, mtd->writesize, &read, rbuffer);
	if (!err || err == -EUCLEAN)
		err = mtd->ecc_stats.corrected - oldstats.corrected;

	if (err < 0 || read != mtd->writesize) {
		pr_err("error: read failed at %#llx\n", (long long)offset);
		if (err >= 0)
			err = -EIO;
	}

	return err;
}

/* Verifies rbuffer against random sequence */
static int verify_page(int log)
{
	unsigned i, errs = 0;

	if (log)
		pr_info("verify_page\n");

	for (i = 0; i < mtd->writesize; i++) {
		if (rbuffer[i] != hash(i+seed)) {
			pr_err("Error: page offset %u, expected %02x, got %02x\n",
				i, hash(i+seed), rbuffer[i]);
			errs++;
		}
	}

	if (errs)
		return -EIO;
	else
		return 0;
}

#define CBIT(v, n) ((v) & (1 << (n)))
#define BCLR(v, n) ((v) = (v) & ~(1 << (n)))

/* Finds the first '1' bit in wbuffer starting at offset 'byte'
 * and sets it to '0'. */
static int insert_biterror(unsigned byte)
{
	int bit;

	while (byte < mtd->writesize) {
		for (bit = 7; bit >= 0; bit--) {
			if (CBIT(wbuffer[byte], bit)) {
				BCLR(wbuffer[byte], bit);
				pr_info("Inserted biterror @ %u/%u\n", byte, bit);
				return 0;
			}
		}
		byte++;
	}
	pr_err("biterror: Failed to find a '1' bit\n");
	return -EIO;
}

/* Writes 'random' data to page and then introduces deliberate bit
 * errors into the page, while verifying each step. */
static int incremental_errors_test(void)
{
	int err = 0;
	unsigned i;
	unsigned errs_per_subpage = 0;

	pr_info("incremental biterrors test\n");

	for (i = 0; i < mtd->writesize; i++)
		wbuffer[i] = hash(i+seed);

	err = write_page(1);
	if (err)
		goto exit;

	while (1) {

		err = rewrite_page(1);
		if (err)
			goto exit;

		err = read_page(1);
		if (err > 0)
			pr_info("Read reported %d corrected bit errors\n", err);
		if (err < 0) {
			pr_err("After %d biterrors per subpage, read reported error %d\n",
				errs_per_subpage, err);
			err = 0;
			goto exit;
		}

		err = verify_page(1);
		if (err) {
			pr_err("ECC failure, read data is incorrect despite read success\n");
			goto exit;
		}

		pr_info("Successfully corrected %d bit errors per subpage\n",
			errs_per_subpage);

		for (i = 0; i < subcount; i++) {
			err = insert_biterror(i * subsize);
			if (err < 0)
				goto exit;
		}
		errs_per_subpage++;
	}

exit:
	return err;
}


/* Writes 'random' data to page and then re-writes that same data repeatedly.
   This eventually develops bit errors (bits written as '1' will slowly become
   '0'), which are corrected as far as the ECC is capable of. */
static int overwrite_test(void)
{
	int err = 0;
	unsigned i;
	unsigned max_corrected = 0;
	unsigned opno = 0;
	/* We don't expect more than this many correctable bit errors per
	 * page. */
	#define MAXBITS 512
	static unsigned bitstats[MAXBITS]; /* bit error histogram. */

	memset(bitstats, 0, sizeof(bitstats));

	pr_info("overwrite biterrors test\n");

	for (i = 0; i < mtd->writesize; i++)
		wbuffer[i] = hash(i+seed);

	err = write_page(1);
	if (err)
		goto exit;

	while (opno < max_overwrite) {

		err = write_page(0);
		if (err)
			break;

		err = read_page(0);
		if (err >= 0) {
			if (err >= MAXBITS) {
				pr_info("Implausible number of bit errors corrected\n");
				err = -EIO;
				break;
			}
			bitstats[err]++;
			if (err > max_corrected) {
				max_corrected = err;
				pr_info("Read reported %d corrected bit errors\n",
					err);
			}
		} else { /* err < 0 */
			pr_info("Read reported error %d\n", err);
			err = 0;
			break;
		}

		err = verify_page(0);
		if (err) {
			bitstats[max_corrected] = opno;
			pr_info("ECC failure, read data is incorrect despite read success\n");
			break;
		}

		err = mtdtest_relax();
		if (err)
			break;

		opno++;
	}

	/* At this point bitstats[0] contains the number of ops with no bit
	 * errors, bitstats[1] the number of ops with 1 bit error, etc. */
	pr_info("Bit error histogram (%d operations total):\n", opno);
	for (i = 0; i < max_corrected; i++)
		pr_info("Page reads with %3d corrected bit errors: %d\n",
			i, bitstats[i]);

exit:
	return err;
}

static int __init mtd_nandbiterrs_init(void)
{
	int err = 0;

	printk("\n");
	printk(KERN_INFO "==================================================\n");
	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");
		goto exit_mtddev;
	}

	if (!mtd_type_is_nand(mtd)) {
		pr_info("this test requires NAND flash\n");
		err = -ENODEV;
		goto exit_nand;
	}

	pr_info("MTD device size %llu, eraseblock=%u, page=%u, oob=%u\n",
		(unsigned long long)mtd->size, mtd->erasesize,
		mtd->writesize, mtd->oobsize);

	subsize  = mtd->writesize >> mtd->subpage_sft;
	subcount = mtd->writesize / subsize;

	pr_info("Device uses %d subpages of %d bytes\n", subcount, subsize);

	offset     = (loff_t)page_offset * mtd->writesize;
	eraseblock = mtd_div_by_eb(offset, mtd);

	pr_info("Using page=%u, offset=%llu, eraseblock=%u\n",
		page_offset, offset, eraseblock);

	wbuffer = kmalloc(mtd->writesize, GFP_KERNEL);
	if (!wbuffer) {
		err = -ENOMEM;
		goto exit_wbuffer;
	}

	rbuffer = kmalloc(mtd->writesize, GFP_KERNEL);
	if (!rbuffer) {
		err = -ENOMEM;
		goto exit_rbuffer;
	}

	err = mtdtest_erase_eraseblock(mtd, eraseblock);
	if (err)
		goto exit_error;

	if (mode == 0)
		err = incremental_errors_test();
	else
		err = overwrite_test();

	if (err)
		goto exit_error;

	/* We leave the block un-erased in case of test failure. */
	err = mtdtest_erase_eraseblock(mtd, eraseblock);
	if (err)
		goto exit_error;

	err = -EIO;
	pr_info("finished successfully.\n");
	printk(KERN_INFO "==================================================\n");

exit_error:
	kfree(rbuffer);
exit_rbuffer:
	kfree(wbuffer);
exit_wbuffer:
	/* Nothing */
exit_nand:
	put_mtd_device(mtd);
exit_mtddev:
	return err;
}

static void __exit mtd_nandbiterrs_exit(void)
{
	return;
}

module_init(mtd_nandbiterrs_init);
module_exit(mtd_nandbiterrs_exit);

MODULE_DESCRIPTION("NAND bit error recovery test");
MODULE_AUTHOR("Iwo Mergler");
MODULE_LICENSE("GPL");
Commit	Line	Data
4cd10358	1	// SPDX-License-Identifier: GPL-2.0-only
3cf06f4f IM	2	/*
	3	* Copyright © 2012 NetCommWireless
	4	* Iwo Mergler <Iwo.Mergler@netcommwireless.com.au>
	5	*
	6	* Test for multi-bit error recovery on a NAND page This mostly tests the
	7	* ECC controller / driver.
	8	*
	9	* There are two test modes:
	10	*
	11	* 0 - artificially inserting bit errors until the ECC fails
	12	* This is the default method and fairly quick. It should
	13	* be independent of the quality of the FLASH.
	14	*
	15	* 1 - re-writing the same pattern repeatedly until the ECC fails.
	16	* This method relies on the physics of NAND FLASH to eventually
	17	* generate '0' bits if '1' has been written sufficient times.
	18	* Depending on the NAND, the first bit errors will appear after
	19	* 1000 or more writes and then will usually snowball, reaching the
	20	* limits of the ECC quickly.
	21	*
	22	* The test stops after 10000 cycles, should your FLASH be
	23	* exceptionally good and not generate bit errors before that. Try
	24	* a different page in that case.
	25	*
	26	* Please note that neither of these tests will significantly 'use up' any
	27	* FLASH endurance. Only a maximum of two erase operations will be performed.
3cf06f4f	28	*/
600ed675 VN	29
	30	#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
	31
3cf06f4f IM	32	#include <linux/init.h>
	33	#include <linux/module.h>
	34	#include <linux/moduleparam.h>
	35	#include <linux/mtd/mtd.h>
	36	#include <linux/err.h>
d4092d76	37	#include <linux/mtd/rawnand.h>
3cf06f4f	38	#include <linux/slab.h>
56177516	39	#include "mtd_test.h"
3cf06f4f	40
3cf06f4f IM	41	static int dev;
	42	module_param(dev, int, S_IRUGO);
	43	MODULE_PARM_DESC(dev, "MTD device number to use");
	44
	45	static unsigned page_offset;
	46	module_param(page_offset, uint, S_IRUGO);
	47	MODULE_PARM_DESC(page_offset, "Page number relative to dev start");
	48
	49	static unsigned seed;
	50	module_param(seed, uint, S_IRUGO);
	51	MODULE_PARM_DESC(seed, "Random seed");
	52
	53	static int mode;
	54	module_param(mode, int, S_IRUGO);
	55	MODULE_PARM_DESC(mode, "0=incremental errors, 1=overwrite test");
	56
	57	static unsigned max_overwrite = 10000;
	58
	59	static loff_t offset; /* Offset of the page we're using. */
	60	static unsigned eraseblock; /* Eraseblock number for our page. */
	61
	62	/* We assume that the ECC can correct up to a certain number
	63	* of biterrors per subpage. */
	64	static unsigned subsize; /* Size of subpages */
	65	static unsigned subcount; /* Number of subpages per page */
	66
	67	static struct mtd_info mtd; / MTD device */
	68
	69	static uint8_t wbuffer; / One page write / compare buffer */
	70	static uint8_t rbuffer; / One page read buffer */
	71
	72	/* 'random' bytes from known offsets */
	73	static uint8_t hash(unsigned offset)
	74	{
	75	unsigned v = offset;
	76	unsigned char c;
	77	v ^= 0x7f7edfd3;
	78	v = v ^ (v >> 3);
	79	v = v ^ (v >> 5);
	80	v = v ^ (v >> 13);
	81	c = v & 0xFF;
	82	/* Reverse bits of result. */
	83	c = (c & 0x0F) << 4 \| (c & 0xF0) >> 4;
	84	c = (c & 0x33) << 2 \| (c & 0xCC) >> 2;
	85	c = (c & 0x55) << 1 \| (c & 0xAA) >> 1;
	86	return c;
	87	}
	88
3cf06f4f IM	89	/* Writes wbuffer to page */
	90	static int write_page(int log)
	91	{
3cf06f4f	92	if (log)
600ed675	93	pr_info("write_page\n");
3cf06f4f	94
8a9f4aa3	95	return mtdtest_write(mtd, offset, mtd->writesize, wbuffer);
3cf06f4f IM	96	}
	97
	98	/* Re-writes the data area while leaving the OOB alone. */
	99	static int rewrite_page(int log)
	100	{
	101	int err = 0;
	102	struct mtd_oob_ops ops;
	103
	104	if (log)
600ed675	105	pr_info("rewrite page\n");
3cf06f4f IM	106
	107	ops.mode = MTD_OPS_RAW; /* No ECC */
	108	ops.len = mtd->writesize;
	109	ops.retlen = 0;
	110	ops.ooblen = 0;
	111	ops.oobretlen = 0;
	112	ops.ooboffs = 0;
	113	ops.datbuf = wbuffer;
	114	ops.oobbuf = NULL;
	115
	116	err = mtd_write_oob(mtd, offset, &ops);
	117	if (err \|\| ops.retlen != mtd->writesize) {
600ed675	118	pr_err("error: write_oob failed (%d)\n", err);
3cf06f4f IM	119	if (!err)
	120	err = -EIO;
	121	}
	122
	123	return err;
	124	}
	125
	126	/* Reads page into rbuffer. Returns number of corrected bit errors (>=0)
	127	* or error (<0) */
	128	static int read_page(int log)
	129	{
	130	int err = 0;
	131	size_t read;
	132	struct mtd_ecc_stats oldstats;
	133
	134	if (log)
600ed675	135	pr_info("read_page\n");
3cf06f4f IM	136
	137	/* Saving last mtd stats */
	138	memcpy(&oldstats, &mtd->ecc_stats, sizeof(oldstats));
	139
	140	err = mtd_read(mtd, offset, mtd->writesize, &read, rbuffer);
6cbefbdc	141	if (!err \|\| err == -EUCLEAN)
3cf06f4f IM	142	err = mtd->ecc_stats.corrected - oldstats.corrected;
	143
	144	if (err < 0 \|\| read != mtd->writesize) {
600ed675	145	pr_err("error: read failed at %#llx\n", (long long)offset);
3cf06f4f IM	146	if (err >= 0)
	147	err = -EIO;
	148	}
	149
	150	return err;
	151	}
	152
	153	/* Verifies rbuffer against random sequence */
	154	static int verify_page(int log)
	155	{
	156	unsigned i, errs = 0;
	157
	158	if (log)
600ed675	159	pr_info("verify_page\n");
3cf06f4f IM	160
	161	for (i = 0; i < mtd->writesize; i++) {
	162	if (rbuffer[i] != hash(i+seed)) {
600ed675	163	pr_err("Error: page offset %u, expected %02x, got %02x\n",
3cf06f4f IM	164	i, hash(i+seed), rbuffer[i]);
	165	errs++;
	166	}
	167	}
	168
	169	if (errs)
	170	return -EIO;
	171	else
	172	return 0;
	173	}
	174
	175	#define CBIT(v, n) ((v) & (1 << (n)))
	176	#define BCLR(v, n) ((v) = (v) & ~(1 << (n)))
	177
	178	/* Finds the first '1' bit in wbuffer starting at offset 'byte'
	179	* and sets it to '0'. */
	180	static int insert_biterror(unsigned byte)
	181	{
	182	int bit;
	183
	184	while (byte < mtd->writesize) {
	185	for (bit = 7; bit >= 0; bit--) {
	186	if (CBIT(wbuffer[byte], bit)) {
	187	BCLR(wbuffer[byte], bit);
600ed675	188	pr_info("Inserted biterror @ %u/%u\n", byte, bit);
3cf06f4f IM	189	return 0;
	190	}
	191	}
	192	byte++;
	193	}
600ed675	194	pr_err("biterror: Failed to find a '1' bit\n");
3cf06f4f IM	195	return -EIO;
	196	}
	197
	198	/* Writes 'random' data to page and then introduces deliberate bit
	199	* errors into the page, while verifying each step. */
	200	static int incremental_errors_test(void)
	201	{
	202	int err = 0;
	203	unsigned i;
	204	unsigned errs_per_subpage = 0;
	205
600ed675	206	pr_info("incremental biterrors test\n");
3cf06f4f IM	207
	208	for (i = 0; i < mtd->writesize; i++)
	209	wbuffer[i] = hash(i+seed);
	210
	211	err = write_page(1);
	212	if (err)
	213	goto exit;
	214
	215	while (1) {
	216
	217	err = rewrite_page(1);
	218	if (err)
	219	goto exit;
	220
	221	err = read_page(1);
	222	if (err > 0)
600ed675	223	pr_info("Read reported %d corrected bit errors\n", err);
3cf06f4f	224	if (err < 0) {
600ed675	225	pr_err("After %d biterrors per subpage, read reported error %d\n",
3cf06f4f IM	226	errs_per_subpage, err);
	227	err = 0;
	228	goto exit;
	229	}
	230
	231	err = verify_page(1);
	232	if (err) {
600ed675	233	pr_err("ECC failure, read data is incorrect despite read success\n");
3cf06f4f IM	234	goto exit;
	235	}
	236
600ed675	237	pr_info("Successfully corrected %d bit errors per subpage\n",
3cf06f4f IM	238	errs_per_subpage);
	239
	240	for (i = 0; i < subcount; i++) {
	241	err = insert_biterror(i * subsize);
	242	if (err < 0)
	243	goto exit;
	244	}
	245	errs_per_subpage++;
	246	}
	247
	248	exit:
	249	return err;
	250	}
	251
	252
	253	/* Writes 'random' data to page and then re-writes that same data repeatedly.
	254	This eventually develops bit errors (bits written as '1' will slowly become
	255	'0'), which are corrected as far as the ECC is capable of. */
	256	static int overwrite_test(void)
	257	{
	258	int err = 0;
	259	unsigned i;
	260	unsigned max_corrected = 0;
	261	unsigned opno = 0;
	262	/* We don't expect more than this many correctable bit errors per
	263	* page. */
	264	#define MAXBITS 512
	265	static unsigned bitstats[MAXBITS]; /* bit error histogram. */
	266
	267	memset(bitstats, 0, sizeof(bitstats));
	268
600ed675	269	pr_info("overwrite biterrors test\n");
3cf06f4f IM	270
	271	for (i = 0; i < mtd->writesize; i++)
	272	wbuffer[i] = hash(i+seed);
	273
	274	err = write_page(1);
	275	if (err)
	276	goto exit;
	277
	278	while (opno < max_overwrite) {
	279
97b67131	280	err = write_page(0);
3cf06f4f IM	281	if (err)
	282	break;
	283
	284	err = read_page(0);
	285	if (err >= 0) {
	286	if (err >= MAXBITS) {
600ed675	287	pr_info("Implausible number of bit errors corrected\n");
3cf06f4f IM	288	err = -EIO;
	289	break;
	290	}
	291	bitstats[err]++;
	292	if (err > max_corrected) {
	293	max_corrected = err;
600ed675	294	pr_info("Read reported %d corrected bit errors\n",
3cf06f4f IM	295	err);
	296	}
	297	} else { /* err < 0 */
600ed675	298	pr_info("Read reported error %d\n", err);
3cf06f4f IM	299	err = 0;
	300	break;
	301	}
	302
	303	err = verify_page(0);
	304	if (err) {
	305	bitstats[max_corrected] = opno;
600ed675	306	pr_info("ECC failure, read data is incorrect despite read success\n");
3cf06f4f IM	307	break;
	308	}
	309
2a6a28e7 RW	310	err = mtdtest_relax();
	311	if (err)
	312	break;
	313
3cf06f4f IM	314	opno++;
	315	}
	316
	317	/* At this point bitstats[0] contains the number of ops with no bit
	318	* errors, bitstats[1] the number of ops with 1 bit error, etc. */
600ed675	319	pr_info("Bit error histogram (%d operations total):\n", opno);
3cf06f4f	320	for (i = 0; i < max_corrected; i++)
600ed675	321	pr_info("Page reads with %3d corrected bit errors: %d\n",
3cf06f4f IM	322	i, bitstats[i]);
	323
	324	exit:
	325	return err;
	326	}
	327
	328	static int __init mtd_nandbiterrs_init(void)
	329	{
	330	int err = 0;
	331
600ed675 VN	332	printk("\n");
	333	printk(KERN_INFO "==================================================\n");
	334	pr_info("MTD device: %d\n", dev);
3cf06f4f IM	335
	336	mtd = get_mtd_device(NULL, dev);
	337	if (IS_ERR(mtd)) {
	338	err = PTR_ERR(mtd);
600ed675	339	pr_err("error: cannot get MTD device\n");
3cf06f4f IM	340	goto exit_mtddev;
	341	}
	342
818b9739	343	if (!mtd_type_is_nand(mtd)) {
600ed675	344	pr_info("this test requires NAND flash\n");
3cf06f4f IM	345	err = -ENODEV;
	346	goto exit_nand;
	347	}
	348
600ed675	349	pr_info("MTD device size %llu, eraseblock=%u, page=%u, oob=%u\n",
3cf06f4f IM	350	(unsigned long long)mtd->size, mtd->erasesize,
	351	mtd->writesize, mtd->oobsize);
	352
	353	subsize = mtd->writesize >> mtd->subpage_sft;
	354	subcount = mtd->writesize / subsize;
	355
600ed675	356	pr_info("Device uses %d subpages of %d bytes\n", subcount, subsize);
3cf06f4f	357
1001ff7a	358	offset = (loff_t)page_offset * mtd->writesize;
3cf06f4f IM	359	eraseblock = mtd_div_by_eb(offset, mtd);
3cf06f4f IM	360
600ed675	361	pr_info("Using page=%u, offset=%llu, eraseblock=%u\n",
3cf06f4f IM	362	page_offset, offset, eraseblock);
	363
	364	wbuffer = kmalloc(mtd->writesize, GFP_KERNEL);
	365	if (!wbuffer) {
	366	err = -ENOMEM;
	367	goto exit_wbuffer;
	368	}
	369
	370	rbuffer = kmalloc(mtd->writesize, GFP_KERNEL);
	371	if (!rbuffer) {
	372	err = -ENOMEM;
	373	goto exit_rbuffer;
	374	}
	375
56177516	376	err = mtdtest_erase_eraseblock(mtd, eraseblock);
3cf06f4f IM	377	if (err)
	378	goto exit_error;
	379
	380	if (mode == 0)
	381	err = incremental_errors_test();
	382	else
	383	err = overwrite_test();
	384
	385	if (err)
	386	goto exit_error;
	387
	388	/* We leave the block un-erased in case of test failure. */
56177516	389	err = mtdtest_erase_eraseblock(mtd, eraseblock);
3cf06f4f IM	390	if (err)
	391	goto exit_error;
	392
	393	err = -EIO;
600ed675 VN	394	pr_info("finished successfully.\n");
600ed675 VN	395	printk(KERN_INFO "==================================================\n");
3cf06f4f IM	396
	397	exit_error:
	398	kfree(rbuffer);
	399	exit_rbuffer:
	400	kfree(wbuffer);
	401	exit_wbuffer:
	402	/* Nothing */
	403	exit_nand:
	404	put_mtd_device(mtd);
	405	exit_mtddev:
	406	return err;
	407	}
	408
	409	static void __exit mtd_nandbiterrs_exit(void)
	410	{
	411	return;
	412	}
	413
	414	module_init(mtd_nandbiterrs_init);
	415	module_exit(mtd_nandbiterrs_exit);
	416
	417	MODULE_DESCRIPTION("NAND bit error recovery test");
	418	MODULE_AUTHOR("Iwo Mergler");
	419	MODULE_LICENSE("GPL");