mtd: move NAND files into a raw/ subdirectory

NAND flavors, like serial and parallel, have a lot in common and would
benefit to share code. Let's move raw (parallel) NAND specific code in a
raw/ subdirectory, to ease the addition of a core file in nand/ and the
introduction of a spi/ subdirectory specific to SPI NANDs.

Signed-off-by: Miquel Raynal <miquel.raynal@bootlin.com>

1 files changed, 904 insertions, 0 deletions

diff --git a/drivers/mtd/nand/raw/nand_util.c b/drivers/mtd/nand/raw/nand_util.c
new file mode 100644
index 0000000000..fc2235c1a0
--- /dev/null
+++ b/drivers/mtd/nand/raw/nand_util.c
@@ -0,0 +1,904 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * drivers/mtd/nand/raw/nand_util.c
+ *
+ * Copyright (C) 2006 by Weiss-Electronic GmbH.
+ * All rights reserved.
+ *
+ * @author:	Guido Classen <clagix@gmail.com>
+ * @descr:	NAND Flash support
+ * @references: borrowed heavily from Linux mtd-utils code:
+ *		flash_eraseall.c by Arcom Control System Ltd
+ *		nandwrite.c by Steven J. Hill (sjhill@realitydiluted.com)
+ *			       and Thomas Gleixner (tglx@linutronix.de)
+ *
+ * Copyright (C) 2008 Nokia Corporation: drop_ffs() function by
+ * Artem Bityutskiy <dedekind1@gmail.com> from mtd-utils
+ *
+ * Copyright 2010 Freescale Semiconductor
+ */
+
+#include <common.h>
+#include <command.h>
+#include <watchdog.h>
+#include <malloc.h>
+#include <memalign.h>
+#include <div64.h>
+
+#include <linux/errno.h>
+#include <linux/mtd/mtd.h>
+#include <nand.h>
+#include <jffs2/jffs2.h>
+
+typedef struct erase_info	erase_info_t;
+typedef struct mtd_info		mtd_info_t;
+
+/* support only for native endian JFFS2 */
+#define cpu_to_je16(x) (x)
+#define cpu_to_je32(x) (x)
+
+/**
+ * nand_erase_opts: - erase NAND flash with support for various options
+ *		      (jffs2 formatting)
+ *
+ * @param mtd		nand mtd instance to erase
+ * @param opts		options,  @see struct nand_erase_options
+ * @return		0 in case of success
+ *
+ * This code is ported from flash_eraseall.c from Linux mtd utils by
+ * Arcom Control System Ltd.
+ */
+int nand_erase_opts(struct mtd_info *mtd,
+		    const nand_erase_options_t *opts)
+{
+	struct jffs2_unknown_node cleanmarker;
+	erase_info_t erase;
+	unsigned long erase_length, erased_length; /* in blocks */
+	int result;
+	int percent_complete = -1;
+	const char *mtd_device = mtd->name;
+	struct mtd_oob_ops oob_opts;
+	struct nand_chip *chip = mtd_to_nand(mtd);
+
+	if ((opts->offset & (mtd->erasesize - 1)) != 0) {
+		printf("Attempt to erase non block-aligned data\n");
+		return -1;
+	}
+
+	memset(&erase, 0, sizeof(erase));
+	memset(&oob_opts, 0, sizeof(oob_opts));
+
+	erase.mtd = mtd;
+	erase.len = mtd->erasesize;
+	erase.addr = opts->offset;
+	erase_length = lldiv(opts->length + mtd->erasesize - 1,
+			     mtd->erasesize);
+
+	cleanmarker.magic = cpu_to_je16(JFFS2_MAGIC_BITMASK);
+	cleanmarker.nodetype = cpu_to_je16(JFFS2_NODETYPE_CLEANMARKER);
+	cleanmarker.totlen = cpu_to_je32(8);
+
+	/* scrub option allows to erase badblock. To prevent internal
+	 * check from erase() method, set block check method to dummy
+	 * and disable bad block table while erasing.
+	 */
+	if (opts->scrub) {
+		erase.scrub = opts->scrub;
+		/*
+		 * We don't need the bad block table anymore...
+		 * after scrub, there are no bad blocks left!
+		 */
+		if (chip->bbt) {
+			kfree(chip->bbt);
+		}
+		chip->bbt = NULL;
+		chip->options &= ~NAND_BBT_SCANNED;
+	}
+
+	for (erased_length = 0;
+	     erased_length < erase_length;
+	     erase.addr += mtd->erasesize) {
+
+		WATCHDOG_RESET();
+
+		if (opts->lim && (erase.addr >= (opts->offset + opts->lim))) {
+			puts("Size of erase exceeds limit\n");
+			return -EFBIG;
+		}
+		if (!opts->scrub) {
+			int ret = mtd_block_isbad(mtd, erase.addr);
+			if (ret > 0) {
+				if (!opts->quiet)
+					printf("\rSkipping bad block at  "
+					       "0x%08llx                 "
+					       "                         \n",
+					       erase.addr);
+
+				if (!opts->spread)
+					erased_length++;
+
+				continue;
+
+			} else if (ret < 0) {
+				printf("\n%s: MTD get bad block failed: %d\n",
+				       mtd_device,
+				       ret);
+				return -1;
+			}
+		}
+
+		erased_length++;
+
+		result = mtd_erase(mtd, &erase);
+		if (result != 0) {
+			printf("\n%s: MTD Erase failure: %d\n",
+			       mtd_device, result);
+			continue;
+		}
+
+		/* format for JFFS2 ? */
+		if (opts->jffs2 && chip->ecc.layout->oobavail >= 8) {
+			struct mtd_oob_ops ops;
+			ops.ooblen = 8;
+			ops.datbuf = NULL;
+			ops.oobbuf = (uint8_t *)&cleanmarker;
+			ops.ooboffs = 0;
+			ops.mode = MTD_OPS_AUTO_OOB;
+
+			result = mtd_write_oob(mtd, erase.addr, &ops);
+			if (result != 0) {
+				printf("\n%s: MTD writeoob failure: %d\n",
+				       mtd_device, result);
+				continue;
+			}
+		}
+
+		if (!opts->quiet) {
+			unsigned long long n = erased_length * 100ULL;
+			int percent;
+
+			do_div(n, erase_length);
+			percent = (int)n;
+
+			/* output progress message only at whole percent
+			 * steps to reduce the number of messages printed
+			 * on (slow) serial consoles
+			 */
+			if (percent != percent_complete) {
+				percent_complete = percent;
+
+				printf("\rErasing at 0x%llx -- %3d%% complete.",
+				       erase.addr, percent);
+
+				if (opts->jffs2 && result == 0)
+					printf(" Cleanmarker written at 0x%llx.",
+					       erase.addr);
+			}
+		}
+	}
+	if (!opts->quiet)
+		printf("\n");
+
+	return 0;
+}
+
+#ifdef CONFIG_CMD_NAND_LOCK_UNLOCK
+
+#define NAND_CMD_LOCK_TIGHT     0x2c
+#define NAND_CMD_LOCK_STATUS    0x7a
+ 
+/******************************************************************************
+ * Support for locking / unlocking operations of some NAND devices
+ *****************************************************************************/
+
+/**
+ * nand_lock: Set all pages of NAND flash chip to the LOCK or LOCK-TIGHT
+ *	      state
+ *
+ * @param mtd		nand mtd instance
+ * @param tight		bring device in lock tight mode
+ *
+ * @return		0 on success, -1 in case of error
+ *
+ * The lock / lock-tight command only applies to the whole chip. To get some
+ * parts of the chip lock and others unlocked use the following sequence:
+ *
+ * - Lock all pages of the chip using nand_lock(mtd, 0) (or the lockpre pin)
+ * - Call nand_unlock() once for each consecutive area to be unlocked
+ * - If desired: Bring the chip to the lock-tight state using nand_lock(mtd, 1)
+ *
+ *   If the device is in lock-tight state software can't change the
+ *   current active lock/unlock state of all pages. nand_lock() / nand_unlock()
+ *   calls will fail. It is only posible to leave lock-tight state by
+ *   an hardware signal (low pulse on _WP pin) or by power down.
+ */
+int nand_lock(struct mtd_info *mtd, int tight)
+{
+	int ret = 0;
+	int status;
+	struct nand_chip *chip = mtd_to_nand(mtd);
+
+	/* select the NAND device */
+	chip->select_chip(mtd, 0);
+
+	/* check the Lock Tight Status */
+	chip->cmdfunc(mtd, NAND_CMD_LOCK_STATUS, -1, 0);
+	if (chip->read_byte(mtd) & NAND_LOCK_STATUS_TIGHT) {
+		printf("nand_lock: Device is locked tight!\n");
+		ret = -1;
+		goto out;
+	}
+
+	chip->cmdfunc(mtd,
+		      (tight ? NAND_CMD_LOCK_TIGHT : NAND_CMD_LOCK),
+		      -1, -1);
+
+	/* call wait ready function */
+	status = chip->waitfunc(mtd, chip);
+
+	/* see if device thinks it succeeded */
+	if (status & 0x01) {
+		ret = -1;
+	}
+
+ out:
+	/* de-select the NAND device */
+	chip->select_chip(mtd, -1);
+	return ret;
+}
+
+/**
+ * nand_get_lock_status: - query current lock state from one page of NAND
+ *			   flash
+ *
+ * @param mtd		nand mtd instance
+ * @param offset	page address to query (must be page-aligned!)
+ *
+ * @return		-1 in case of error
+ *			>0 lock status:
+ *			  bitfield with the following combinations:
+ *			  NAND_LOCK_STATUS_TIGHT: page in tight state
+ *			  NAND_LOCK_STATUS_UNLOCK: page unlocked
+ *
+ */
+int nand_get_lock_status(struct mtd_info *mtd, loff_t offset)
+{
+	int ret = 0;
+	int chipnr;
+	int page;
+	struct nand_chip *chip = mtd_to_nand(mtd);
+
+	/* select the NAND device */
+	chipnr = (int)(offset >> chip->chip_shift);
+	chip->select_chip(mtd, chipnr);
+
+
+	if ((offset & (mtd->writesize - 1)) != 0) {
+		printf("nand_get_lock_status: "
+			"Start address must be beginning of "
+			"nand page!\n");
+		ret = -1;
+		goto out;
+	}
+
+	/* check the Lock Status */
+	page = (int)(offset >> chip->page_shift);
+	chip->cmdfunc(mtd, NAND_CMD_LOCK_STATUS, -1, page & chip->pagemask);
+
+	ret = chip->read_byte(mtd) & (NAND_LOCK_STATUS_TIGHT
+					  | NAND_LOCK_STATUS_UNLOCK);
+
+ out:
+	/* de-select the NAND device */
+	chip->select_chip(mtd, -1);
+	return ret;
+}
+
+/**
+ * nand_unlock: - Unlock area of NAND pages
+ *		  only one consecutive area can be unlocked at one time!
+ *
+ * @param mtd		nand mtd instance
+ * @param start		start byte address
+ * @param length	number of bytes to unlock (must be a multiple of
+ *			page size mtd->writesize)
+ * @param allexcept	if set, unlock everything not selected
+ *
+ * @return		0 on success, -1 in case of error
+ */
+int nand_unlock(struct mtd_info *mtd, loff_t start, size_t length,
+	int allexcept)
+{
+	int ret = 0;
+	int chipnr;
+	int status;
+	int page;
+	struct nand_chip *chip = mtd_to_nand(mtd);
+
+	debug("nand_unlock%s: start: %08llx, length: %zd!\n",
+		allexcept ? " (allexcept)" : "", start, length);
+
+	/* select the NAND device */
+	chipnr = (int)(start >> chip->chip_shift);
+	chip->select_chip(mtd, chipnr);
+
+	/* check the WP bit */
+	chip->cmdfunc(mtd, NAND_CMD_STATUS, -1, -1);
+	if (!(chip->read_byte(mtd) & NAND_STATUS_WP)) {
+		printf("nand_unlock: Device is write protected!\n");
+		ret = -1;
+		goto out;
+	}
+
+	/* check the Lock Tight Status */
+	page = (int)(start >> chip->page_shift);
+	chip->cmdfunc(mtd, NAND_CMD_LOCK_STATUS, -1, page & chip->pagemask);
+	if (chip->read_byte(mtd) & NAND_LOCK_STATUS_TIGHT) {
+		printf("nand_unlock: Device is locked tight!\n");
+		ret = -1;
+		goto out;
+	}
+
+	if ((start & (mtd->erasesize - 1)) != 0) {
+		printf("nand_unlock: Start address must be beginning of "
+			"nand block!\n");
+		ret = -1;
+		goto out;
+	}
+
+	if (length == 0 || (length & (mtd->erasesize - 1)) != 0) {
+		printf("nand_unlock: Length must be a multiple of nand block "
+			"size %08x!\n", mtd->erasesize);
+		ret = -1;
+		goto out;
+	}
+
+	/*
+	 * Set length so that the last address is set to the
+	 * starting address of the last block
+	 */
+	length -= mtd->erasesize;
+
+	/* submit address of first page to unlock */
+	chip->cmdfunc(mtd, NAND_CMD_UNLOCK1, -1, page & chip->pagemask);
+
+	/* submit ADDRESS of LAST page to unlock */
+	page += (int)(length >> chip->page_shift);
+
+	/*
+	 * Page addresses for unlocking are supposed to be block-aligned.
+	 * At least some NAND chips use the low bit to indicate that the
+	 * page range should be inverted.
+	 */
+	if (allexcept)
+		page |= 1;
+
+	chip->cmdfunc(mtd, NAND_CMD_UNLOCK2, -1, page & chip->pagemask);
+
+	/* call wait ready function */
+	status = chip->waitfunc(mtd, chip);
+	/* see if device thinks it succeeded */
+	if (status & 0x01) {
+		/* there was an error */
+		ret = -1;
+		goto out;
+	}
+
+ out:
+	/* de-select the NAND device */
+	chip->select_chip(mtd, -1);
+	return ret;
+}
+#endif
+
+/**
+ * check_skip_len
+ *
+ * Check if there are any bad blocks, and whether length including bad
+ * blocks fits into device
+ *
+ * @param mtd nand mtd instance
+ * @param offset offset in flash
+ * @param length image length
+ * @param used length of flash needed for the requested length
+ * @return 0 if the image fits and there are no bad blocks
+ *         1 if the image fits, but there are bad blocks
+ *        -1 if the image does not fit
+ */
+static int check_skip_len(struct mtd_info *mtd, loff_t offset, size_t length,
+			  size_t *used)
+{
+	size_t len_excl_bad = 0;
+	int ret = 0;
+
+	while (len_excl_bad < length) {
+		size_t block_len, block_off;
+		loff_t block_start;
+
+		if (offset >= mtd->size)
+			return -1;
+
+		block_start = offset & ~(loff_t)(mtd->erasesize - 1);
+		block_off = offset & (mtd->erasesize - 1);
+		block_len = mtd->erasesize - block_off;
+
+		if (!nand_block_isbad(mtd, block_start))
+			len_excl_bad += block_len;
+		else
+			ret = 1;
+
+		offset += block_len;
+		*used += block_len;
+	}
+
+	/* If the length is not a multiple of block_len, adjust. */
+	if (len_excl_bad > length)
+		*used -= (len_excl_bad - length);
+
+	return ret;
+}
+
+#ifdef CONFIG_CMD_NAND_TRIMFFS
+static size_t drop_ffs(const struct mtd_info *mtd, const u_char *buf,
+			const size_t *len)
+{
+	size_t l = *len;
+	ssize_t i;
+
+	for (i = l - 1; i >= 0; i--)
+		if (buf[i] != 0xFF)
+			break;
+
+	/* The resulting length must be aligned to the minimum flash I/O size */
+	l = i + 1;
+	l = (l + mtd->writesize - 1) / mtd->writesize;
+	l *=  mtd->writesize;
+
+	/*
+	 * since the input length may be unaligned, prevent access past the end
+	 * of the buffer
+	 */
+	return min(l, *len);
+}
+#endif
+
+/**
+ * nand_verify_page_oob:
+ *
+ * Verify a page of NAND flash, including the OOB.
+ * Reads page of NAND and verifies the contents and OOB against the
+ * values in ops.
+ *
+ * @param mtd		nand mtd instance
+ * @param ops		MTD operations, including data to verify
+ * @param ofs		offset in flash
+ * @return		0 in case of success
+ */
+int nand_verify_page_oob(struct mtd_info *mtd, struct mtd_oob_ops *ops,
+			 loff_t ofs)
+{
+	int rval;
+	struct mtd_oob_ops vops;
+	size_t verlen = mtd->writesize + mtd->oobsize;
+
+	memcpy(&vops, ops, sizeof(vops));
+
+	vops.datbuf = memalign(ARCH_DMA_MINALIGN, verlen);
+
+	if (!vops.datbuf)
+		return -ENOMEM;
+
+	vops.oobbuf = vops.datbuf + mtd->writesize;
+
+	rval = mtd_read_oob(mtd, ofs, &vops);
+	if (!rval)
+		rval = memcmp(ops->datbuf, vops.datbuf, vops.len);
+	if (!rval)
+		rval = memcmp(ops->oobbuf, vops.oobbuf, vops.ooblen);
+
+	free(vops.datbuf);
+
+	return rval ? -EIO : 0;
+}
+
+/**
+ * nand_verify:
+ *
+ * Verify a region of NAND flash.
+ * Reads NAND in page-sized chunks and verifies the contents against
+ * the contents of a buffer.  The offset into the NAND must be
+ * page-aligned, and the function doesn't handle skipping bad blocks.
+ *
+ * @param mtd		nand mtd instance
+ * @param ofs		offset in flash
+ * @param len		buffer length
+ * @param buf		buffer to read from
+ * @return		0 in case of success
+ */
+int nand_verify(struct mtd_info *mtd, loff_t ofs, size_t len, u_char *buf)
+{
+	int rval = 0;
+	size_t verofs;
+	size_t verlen = mtd->writesize;
+	uint8_t *verbuf = memalign(ARCH_DMA_MINALIGN, verlen);
+
+	if (!verbuf)
+		return -ENOMEM;
+
+	/* Read the NAND back in page-size groups to limit malloc size */
+	for (verofs = ofs; verofs < ofs + len;
+	     verofs += verlen, buf += verlen) {
+		verlen = min(mtd->writesize, (uint32_t)(ofs + len - verofs));
+		rval = nand_read(mtd, verofs, &verlen, verbuf);
+		if (!rval || (rval == -EUCLEAN))
+			rval = memcmp(buf, verbuf, verlen);
+
+		if (rval)
+			break;
+	}
+
+	free(verbuf);
+
+	return rval ? -EIO : 0;
+}
+
+
+
+/**
+ * nand_write_skip_bad:
+ *
+ * Write image to NAND flash.
+ * Blocks that are marked bad are skipped and the is written to the next
+ * block instead as long as the image is short enough to fit even after
+ * skipping the bad blocks.  Due to bad blocks we may not be able to
+ * perform the requested write.  In the case where the write would
+ * extend beyond the end of the NAND device, both length and actual (if
+ * not NULL) are set to 0.  In the case where the write would extend
+ * beyond the limit we are passed, length is set to 0 and actual is set
+ * to the required length.
+ *
+ * @param mtd		nand mtd instance
+ * @param offset	offset in flash
+ * @param length	buffer length
+ * @param actual	set to size required to write length worth of
+ *			buffer or 0 on error, if not NULL
+ * @param lim		maximum size that actual may be in order to not
+ *			exceed the buffer
+ * @param buffer        buffer to read from
+ * @param flags		flags modifying the behaviour of the write to NAND
+ * @return		0 in case of success
+ */
+int nand_write_skip_bad(struct mtd_info *mtd, loff_t offset, size_t *length,
+			size_t *actual, loff_t lim, u_char *buffer, int flags)
+{
+	int rval = 0, blocksize;
+	size_t left_to_write = *length;
+	size_t used_for_write = 0;
+	u_char *p_buffer = buffer;
+	int need_skip;
+
+	if (actual)
+		*actual = 0;
+
+	blocksize = mtd->erasesize;
+
+	/*
+	 * nand_write() handles unaligned, partial page writes.
+	 *
+	 * We allow length to be unaligned, for convenience in
+	 * using the $filesize variable.
+	 *
+	 * However, starting at an unaligned offset makes the
+	 * semantics of bad block skipping ambiguous (really,
+	 * you should only start a block skipping access at a
+	 * partition boundary).  So don't try to handle that.
+	 */
+	if ((offset & (mtd->writesize - 1)) != 0) {
+		printf("Attempt to write non page-aligned data\n");
+		*length = 0;
+		return -EINVAL;
+	}
+
+	need_skip = check_skip_len(mtd, offset, *length, &used_for_write);
+
+	if (actual)
+		*actual = used_for_write;
+
+	if (need_skip < 0) {
+		printf("Attempt to write outside the flash area\n");
+		*length = 0;
+		return -EINVAL;
+	}
+
+	if (used_for_write > lim) {
+		puts("Size of write exceeds partition or device limit\n");
+		*length = 0;
+		return -EFBIG;
+	}
+
+	if (!need_skip && !(flags & WITH_DROP_FFS)) {
+		rval = nand_write(mtd, offset, length, buffer);
+
+		if ((flags & WITH_WR_VERIFY) && !rval)
+			rval = nand_verify(mtd, offset, *length, buffer);
+
+		if (rval == 0)
+			return 0;
+
+		*length = 0;
+		printf("NAND write to offset %llx failed %d\n",
+			offset, rval);
+		return rval;
+	}
+
+	while (left_to_write > 0) {
+		size_t block_offset = offset & (mtd->erasesize - 1);
+		size_t write_size, truncated_write_size;
+
+		WATCHDOG_RESET();
+
+		if (nand_block_isbad(mtd, offset & ~(mtd->erasesize - 1))) {
+			printf("Skip bad block 0x%08llx\n",
+				offset & ~(mtd->erasesize - 1));
+			offset += mtd->erasesize - block_offset;
+			continue;
+		}
+
+		if (left_to_write < (blocksize - block_offset))
+			write_size = left_to_write;
+		else
+			write_size = blocksize - block_offset;
+
+		truncated_write_size = write_size;
+#ifdef CONFIG_CMD_NAND_TRIMFFS
+		if (flags & WITH_DROP_FFS)
+			truncated_write_size = drop_ffs(mtd, p_buffer,
+					&write_size);
+#endif
+
+		rval = nand_write(mtd, offset, &truncated_write_size,
+				p_buffer);
+
+		if ((flags & WITH_WR_VERIFY) && !rval)
+			rval = nand_verify(mtd, offset,
+				truncated_write_size, p_buffer);
+
+		offset += write_size;
+		p_buffer += write_size;
+
+		if (rval != 0) {
+			printf("NAND write to offset %llx failed %d\n",
+				offset, rval);
+			*length -= left_to_write;
+			return rval;
+		}
+
+		left_to_write -= write_size;
+	}
+
+	return 0;
+}
+
+/**
+ * nand_read_skip_bad:
+ *
+ * Read image from NAND flash.
+ * Blocks that are marked bad are skipped and the next block is read
+ * instead as long as the image is short enough to fit even after
+ * skipping the bad blocks.  Due to bad blocks we may not be able to
+ * perform the requested read.  In the case where the read would extend
+ * beyond the end of the NAND device, both length and actual (if not
+ * NULL) are set to 0.  In the case where the read would extend beyond
+ * the limit we are passed, length is set to 0 and actual is set to the
+ * required length.
+ *
+ * @param mtd nand mtd instance
+ * @param offset offset in flash
+ * @param length buffer length, on return holds number of read bytes
+ * @param actual set to size required to read length worth of buffer or 0
+ * on error, if not NULL
+ * @param lim maximum size that actual may be in order to not exceed the
+ * buffer
+ * @param buffer buffer to write to
+ * @return 0 in case of success
+ */
+int nand_read_skip_bad(struct mtd_info *mtd, loff_t offset, size_t *length,
+		       size_t *actual, loff_t lim, u_char *buffer)
+{
+	int rval;
+	size_t left_to_read = *length;
+	size_t used_for_read = 0;
+	u_char *p_buffer = buffer;
+	int need_skip;
+
+	if ((offset & (mtd->writesize - 1)) != 0) {
+		printf("Attempt to read non page-aligned data\n");
+		*length = 0;
+		if (actual)
+			*actual = 0;
+		return -EINVAL;
+	}
+
+	need_skip = check_skip_len(mtd, offset, *length, &used_for_read);
+
+	if (actual)
+		*actual = used_for_read;
+
+	if (need_skip < 0) {
+		printf("Attempt to read outside the flash area\n");
+		*length = 0;
+		return -EINVAL;
+	}
+
+	if (used_for_read > lim) {
+		puts("Size of read exceeds partition or device limit\n");
+		*length = 0;
+		return -EFBIG;
+	}
+
+	if (!need_skip) {
+		rval = nand_read(mtd, offset, length, buffer);
+		if (!rval || rval == -EUCLEAN)
+			return 0;
+
+		*length = 0;
+		printf("NAND read from offset %llx failed %d\n",
+			offset, rval);
+		return rval;
+	}
+
+	while (left_to_read > 0) {
+		size_t block_offset = offset & (mtd->erasesize - 1);
+		size_t read_length;
+
+		WATCHDOG_RESET();
+
+		if (nand_block_isbad(mtd, offset & ~(mtd->erasesize - 1))) {
+			printf("Skipping bad block 0x%08llx\n",
+				offset & ~(mtd->erasesize - 1));
+			offset += mtd->erasesize - block_offset;
+			continue;
+		}
+
+		if (left_to_read < (mtd->erasesize - block_offset))
+			read_length = left_to_read;
+		else
+			read_length = mtd->erasesize - block_offset;
+
+		rval = nand_read(mtd, offset, &read_length, p_buffer);
+		if (rval && rval != -EUCLEAN) {
+			printf("NAND read from offset %llx failed %d\n",
+				offset, rval);
+			*length -= left_to_read;
+			return rval;
+		}
+
+		left_to_read -= read_length;
+		offset       += read_length;
+		p_buffer     += read_length;
+	}
+
+	return 0;
+}
+
+#ifdef CONFIG_CMD_NAND_TORTURE
+
+/**
+ * check_pattern:
+ *
+ * Check if buffer contains only a certain byte pattern.
+ *
+ * @param buf buffer to check
+ * @param patt the pattern to check
+ * @param size buffer size in bytes
+ * @return 1 if there are only patt bytes in buf
+ *         0 if something else was found
+ */
+static int check_pattern(const u_char *buf, u_char patt, int size)
+{
+	int i;
+
+	for (i = 0; i < size; i++)
+		if (buf[i] != patt)
+			return 0;
+	return 1;
+}
+
+/**
+ * nand_torture:
+ *
+ * Torture a block of NAND flash.
+ * This is useful to determine if a block that caused a write error is still
+ * good or should be marked as bad.
+ *
+ * @param mtd nand mtd instance
+ * @param offset offset in flash
+ * @return 0 if the block is still good
+ */
+int nand_torture(struct mtd_info *mtd, loff_t offset)
+{
+	u_char patterns[] = {0xa5, 0x5a, 0x00};
+	struct erase_info instr = {
+		.mtd = mtd,
+		.addr = offset,
+		.len = mtd->erasesize,
+	};
+	size_t retlen;
+	int err, ret = -1, i, patt_count;
+	u_char *buf;
+
+	if ((offset & (mtd->erasesize - 1)) != 0) {
+		puts("Attempt to torture a block at a non block-aligned offset\n");
+		return -EINVAL;
+	}
+
+	if (offset + mtd->erasesize > mtd->size) {
+		puts("Attempt to torture a block outside the flash area\n");
+		return -EINVAL;
+	}
+
+	patt_count = ARRAY_SIZE(patterns);
+
+	buf = malloc_cache_aligned(mtd->erasesize);
+	if (buf == NULL) {
+		puts("Out of memory for erase block buffer\n");
+		return -ENOMEM;
+	}
+
+	for (i = 0; i < patt_count; i++) {
+		err = mtd_erase(mtd, &instr);
+		if (err) {
+			printf("%s: erase() failed for block at 0x%llx: %d\n",
+				mtd->name, instr.addr, err);
+			goto out;
+		}
+
+		/* Make sure the block contains only 0xff bytes */
+		err = mtd_read(mtd, offset, mtd->erasesize, &retlen, buf);
+		if ((err && err != -EUCLEAN) || retlen != mtd->erasesize) {
+			printf("%s: read() failed for block at 0x%llx: %d\n",
+				mtd->name, instr.addr, err);
+			goto out;
+		}
+
+		err = check_pattern(buf, 0xff, mtd->erasesize);
+		if (!err) {
+			printf("Erased block at 0x%llx, but a non-0xff byte was found\n",
+				offset);
+			ret = -EIO;
+			goto out;
+		}
+
+		/* Write a pattern and check it */
+		memset(buf, patterns[i], mtd->erasesize);
+		err = mtd_write(mtd, offset, mtd->erasesize, &retlen, buf);
+		if (err || retlen != mtd->erasesize) {
+			printf("%s: write() failed for block at 0x%llx: %d\n",
+				mtd->name, instr.addr, err);
+			goto out;
+		}
+
+		err = mtd_read(mtd, offset, mtd->erasesize, &retlen, buf);
+		if ((err && err != -EUCLEAN) || retlen != mtd->erasesize) {
+			printf("%s: read() failed for block at 0x%llx: %d\n",
+				mtd->name, instr.addr, err);
+			goto out;
+		}
+
+		err = check_pattern(buf, patterns[i], mtd->erasesize);
+		if (!err) {
+			printf("Pattern 0x%.2x checking failed for block at "
+					"0x%llx\n", patterns[i], offset);
+			ret = -EIO;
+			goto out;
+		}
+	}
+
+	ret = 0;
+
+out:
+	free(buf);
+	return ret;
+}
+
+#endif