Adding upstream version 6.6.15.upstream/6.6.15

Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>

1 files changed, 660 insertions, 0 deletions

diff --git a/drivers/mtd/nand/ecc-sw-hamming.c b/drivers/mtd/nand/ecc-sw-hamming.c
new file mode 100644
index 0000000000..254db2e7f8
--- /dev/null
+++ b/drivers/mtd/nand/ecc-sw-hamming.c
@@ -0,0 +1,660 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
+/*
+ * This file contains an ECC algorithm that detects and corrects 1 bit
+ * errors in a 256 byte block of data.
+ *
+ * Copyright © 2008 Koninklijke Philips Electronics NV.
+ *                  Author: Frans Meulenbroeks
+ *
+ * Completely replaces the previous ECC implementation which was written by:
+ *   Steven J. Hill (sjhill@realitydiluted.com)
+ *   Thomas Gleixner (tglx@linutronix.de)
+ *
+ * Information on how this algorithm works and how it was developed
+ * can be found in Documentation/driver-api/mtd/nand_ecc.rst
+ */
+
+#include <linux/types.h>
+#include <linux/kernel.h>
+#include <linux/module.h>
+#include <linux/mtd/nand.h>
+#include <linux/mtd/nand-ecc-sw-hamming.h>
+#include <linux/slab.h>
+#include <asm/byteorder.h>
+
+/*
+ * invparity is a 256 byte table that contains the odd parity
+ * for each byte. So if the number of bits in a byte is even,
+ * the array element is 1, and when the number of bits is odd
+ * the array eleemnt is 0.
+ */
+static const char invparity[256] = {
+	1, 0, 0, 1, 0, 1, 1, 0, 0, 1, 1, 0, 1, 0, 0, 1,
+	0, 1, 1, 0, 1, 0, 0, 1, 1, 0, 0, 1, 0, 1, 1, 0,
+	0, 1, 1, 0, 1, 0, 0, 1, 1, 0, 0, 1, 0, 1, 1, 0,
+	1, 0, 0, 1, 0, 1, 1, 0, 0, 1, 1, 0, 1, 0, 0, 1,
+	0, 1, 1, 0, 1, 0, 0, 1, 1, 0, 0, 1, 0, 1, 1, 0,
+	1, 0, 0, 1, 0, 1, 1, 0, 0, 1, 1, 0, 1, 0, 0, 1,
+	1, 0, 0, 1, 0, 1, 1, 0, 0, 1, 1, 0, 1, 0, 0, 1,
+	0, 1, 1, 0, 1, 0, 0, 1, 1, 0, 0, 1, 0, 1, 1, 0,
+	0, 1, 1, 0, 1, 0, 0, 1, 1, 0, 0, 1, 0, 1, 1, 0,
+	1, 0, 0, 1, 0, 1, 1, 0, 0, 1, 1, 0, 1, 0, 0, 1,
+	1, 0, 0, 1, 0, 1, 1, 0, 0, 1, 1, 0, 1, 0, 0, 1,
+	0, 1, 1, 0, 1, 0, 0, 1, 1, 0, 0, 1, 0, 1, 1, 0,
+	1, 0, 0, 1, 0, 1, 1, 0, 0, 1, 1, 0, 1, 0, 0, 1,
+	0, 1, 1, 0, 1, 0, 0, 1, 1, 0, 0, 1, 0, 1, 1, 0,
+	0, 1, 1, 0, 1, 0, 0, 1, 1, 0, 0, 1, 0, 1, 1, 0,
+	1, 0, 0, 1, 0, 1, 1, 0, 0, 1, 1, 0, 1, 0, 0, 1
+};
+
+/*
+ * bitsperbyte contains the number of bits per byte
+ * this is only used for testing and repairing parity
+ * (a precalculated value slightly improves performance)
+ */
+static const char bitsperbyte[256] = {
+	0, 1, 1, 2, 1, 2, 2, 3, 1, 2, 2, 3, 2, 3, 3, 4,
+	1, 2, 2, 3, 2, 3, 3, 4, 2, 3, 3, 4, 3, 4, 4, 5,
+	1, 2, 2, 3, 2, 3, 3, 4, 2, 3, 3, 4, 3, 4, 4, 5,
+	2, 3, 3, 4, 3, 4, 4, 5, 3, 4, 4, 5, 4, 5, 5, 6,
+	1, 2, 2, 3, 2, 3, 3, 4, 2, 3, 3, 4, 3, 4, 4, 5,
+	2, 3, 3, 4, 3, 4, 4, 5, 3, 4, 4, 5, 4, 5, 5, 6,
+	2, 3, 3, 4, 3, 4, 4, 5, 3, 4, 4, 5, 4, 5, 5, 6,
+	3, 4, 4, 5, 4, 5, 5, 6, 4, 5, 5, 6, 5, 6, 6, 7,
+	1, 2, 2, 3, 2, 3, 3, 4, 2, 3, 3, 4, 3, 4, 4, 5,
+	2, 3, 3, 4, 3, 4, 4, 5, 3, 4, 4, 5, 4, 5, 5, 6,
+	2, 3, 3, 4, 3, 4, 4, 5, 3, 4, 4, 5, 4, 5, 5, 6,
+	3, 4, 4, 5, 4, 5, 5, 6, 4, 5, 5, 6, 5, 6, 6, 7,
+	2, 3, 3, 4, 3, 4, 4, 5, 3, 4, 4, 5, 4, 5, 5, 6,
+	3, 4, 4, 5, 4, 5, 5, 6, 4, 5, 5, 6, 5, 6, 6, 7,
+	3, 4, 4, 5, 4, 5, 5, 6, 4, 5, 5, 6, 5, 6, 6, 7,
+	4, 5, 5, 6, 5, 6, 6, 7, 5, 6, 6, 7, 6, 7, 7, 8,
+};
+
+/*
+ * addressbits is a lookup table to filter out the bits from the xor-ed
+ * ECC data that identify the faulty location.
+ * this is only used for repairing parity
+ * see the comments in nand_ecc_sw_hamming_correct for more details
+ */
+static const char addressbits[256] = {
+	0x00, 0x00, 0x01, 0x01, 0x00, 0x00, 0x01, 0x01,
+	0x02, 0x02, 0x03, 0x03, 0x02, 0x02, 0x03, 0x03,
+	0x00, 0x00, 0x01, 0x01, 0x00, 0x00, 0x01, 0x01,
+	0x02, 0x02, 0x03, 0x03, 0x02, 0x02, 0x03, 0x03,
+	0x04, 0x04, 0x05, 0x05, 0x04, 0x04, 0x05, 0x05,
+	0x06, 0x06, 0x07, 0x07, 0x06, 0x06, 0x07, 0x07,
+	0x04, 0x04, 0x05, 0x05, 0x04, 0x04, 0x05, 0x05,
+	0x06, 0x06, 0x07, 0x07, 0x06, 0x06, 0x07, 0x07,
+	0x00, 0x00, 0x01, 0x01, 0x00, 0x00, 0x01, 0x01,
+	0x02, 0x02, 0x03, 0x03, 0x02, 0x02, 0x03, 0x03,
+	0x00, 0x00, 0x01, 0x01, 0x00, 0x00, 0x01, 0x01,
+	0x02, 0x02, 0x03, 0x03, 0x02, 0x02, 0x03, 0x03,
+	0x04, 0x04, 0x05, 0x05, 0x04, 0x04, 0x05, 0x05,
+	0x06, 0x06, 0x07, 0x07, 0x06, 0x06, 0x07, 0x07,
+	0x04, 0x04, 0x05, 0x05, 0x04, 0x04, 0x05, 0x05,
+	0x06, 0x06, 0x07, 0x07, 0x06, 0x06, 0x07, 0x07,
+	0x08, 0x08, 0x09, 0x09, 0x08, 0x08, 0x09, 0x09,
+	0x0a, 0x0a, 0x0b, 0x0b, 0x0a, 0x0a, 0x0b, 0x0b,
+	0x08, 0x08, 0x09, 0x09, 0x08, 0x08, 0x09, 0x09,
+	0x0a, 0x0a, 0x0b, 0x0b, 0x0a, 0x0a, 0x0b, 0x0b,
+	0x0c, 0x0c, 0x0d, 0x0d, 0x0c, 0x0c, 0x0d, 0x0d,
+	0x0e, 0x0e, 0x0f, 0x0f, 0x0e, 0x0e, 0x0f, 0x0f,
+	0x0c, 0x0c, 0x0d, 0x0d, 0x0c, 0x0c, 0x0d, 0x0d,
+	0x0e, 0x0e, 0x0f, 0x0f, 0x0e, 0x0e, 0x0f, 0x0f,
+	0x08, 0x08, 0x09, 0x09, 0x08, 0x08, 0x09, 0x09,
+	0x0a, 0x0a, 0x0b, 0x0b, 0x0a, 0x0a, 0x0b, 0x0b,
+	0x08, 0x08, 0x09, 0x09, 0x08, 0x08, 0x09, 0x09,
+	0x0a, 0x0a, 0x0b, 0x0b, 0x0a, 0x0a, 0x0b, 0x0b,
+	0x0c, 0x0c, 0x0d, 0x0d, 0x0c, 0x0c, 0x0d, 0x0d,
+	0x0e, 0x0e, 0x0f, 0x0f, 0x0e, 0x0e, 0x0f, 0x0f,
+	0x0c, 0x0c, 0x0d, 0x0d, 0x0c, 0x0c, 0x0d, 0x0d,
+	0x0e, 0x0e, 0x0f, 0x0f, 0x0e, 0x0e, 0x0f, 0x0f
+};
+
+int ecc_sw_hamming_calculate(const unsigned char *buf, unsigned int step_size,
+			     unsigned char *code, bool sm_order)
+{
+	const u32 *bp = (uint32_t *)buf;
+	const u32 eccsize_mult = (step_size == 256) ? 1 : 2;
+	/* current value in buffer */
+	u32 cur;
+	/* rp0..rp17 are the various accumulated parities (per byte) */
+	u32 rp0, rp1, rp2, rp3, rp4, rp5, rp6, rp7, rp8, rp9, rp10, rp11, rp12,
+		rp13, rp14, rp15, rp16, rp17;
+	/* Cumulative parity for all data */
+	u32 par;
+	/* Cumulative parity at the end of the loop (rp12, rp14, rp16) */
+	u32 tmppar;
+	int i;
+
+	par = 0;
+	rp4 = 0;
+	rp6 = 0;
+	rp8 = 0;
+	rp10 = 0;
+	rp12 = 0;
+	rp14 = 0;
+	rp16 = 0;
+	rp17 = 0;
+
+	/*
+	 * The loop is unrolled a number of times;
+	 * This avoids if statements to decide on which rp value to update
+	 * Also we process the data by longwords.
+	 * Note: passing unaligned data might give a performance penalty.
+	 * It is assumed that the buffers are aligned.
+	 * tmppar is the cumulative sum of this iteration.
+	 * needed for calculating rp12, rp14, rp16 and par
+	 * also used as a performance improvement for rp6, rp8 and rp10
+	 */
+	for (i = 0; i < eccsize_mult << 2; i++) {
+		cur = *bp++;
+		tmppar = cur;
+		rp4 ^= cur;
+		cur = *bp++;
+		tmppar ^= cur;
+		rp6 ^= tmppar;
+		cur = *bp++;
+		tmppar ^= cur;
+		rp4 ^= cur;
+		cur = *bp++;
+		tmppar ^= cur;
+		rp8 ^= tmppar;
+
+		cur = *bp++;
+		tmppar ^= cur;
+		rp4 ^= cur;
+		rp6 ^= cur;
+		cur = *bp++;
+		tmppar ^= cur;
+		rp6 ^= cur;
+		cur = *bp++;
+		tmppar ^= cur;
+		rp4 ^= cur;
+		cur = *bp++;
+		tmppar ^= cur;
+		rp10 ^= tmppar;
+
+		cur = *bp++;
+		tmppar ^= cur;
+		rp4 ^= cur;
+		rp6 ^= cur;
+		rp8 ^= cur;
+		cur = *bp++;
+		tmppar ^= cur;
+		rp6 ^= cur;
+		rp8 ^= cur;
+		cur = *bp++;
+		tmppar ^= cur;
+		rp4 ^= cur;
+		rp8 ^= cur;
+		cur = *bp++;
+		tmppar ^= cur;
+		rp8 ^= cur;
+
+		cur = *bp++;
+		tmppar ^= cur;
+		rp4 ^= cur;
+		rp6 ^= cur;
+		cur = *bp++;
+		tmppar ^= cur;
+		rp6 ^= cur;
+		cur = *bp++;
+		tmppar ^= cur;
+		rp4 ^= cur;
+		cur = *bp++;
+		tmppar ^= cur;
+
+		par ^= tmppar;
+		if ((i & 0x1) == 0)
+			rp12 ^= tmppar;
+		if ((i & 0x2) == 0)
+			rp14 ^= tmppar;
+		if (eccsize_mult == 2 && (i & 0x4) == 0)
+			rp16 ^= tmppar;
+	}
+
+	/*
+	 * handle the fact that we use longword operations
+	 * we'll bring rp4..rp14..rp16 back to single byte entities by
+	 * shifting and xoring first fold the upper and lower 16 bits,
+	 * then the upper and lower 8 bits.
+	 */
+	rp4 ^= (rp4 >> 16);
+	rp4 ^= (rp4 >> 8);
+	rp4 &= 0xff;
+	rp6 ^= (rp6 >> 16);
+	rp6 ^= (rp6 >> 8);
+	rp6 &= 0xff;
+	rp8 ^= (rp8 >> 16);
+	rp8 ^= (rp8 >> 8);
+	rp8 &= 0xff;
+	rp10 ^= (rp10 >> 16);
+	rp10 ^= (rp10 >> 8);
+	rp10 &= 0xff;
+	rp12 ^= (rp12 >> 16);
+	rp12 ^= (rp12 >> 8);
+	rp12 &= 0xff;
+	rp14 ^= (rp14 >> 16);
+	rp14 ^= (rp14 >> 8);
+	rp14 &= 0xff;
+	if (eccsize_mult == 2) {
+		rp16 ^= (rp16 >> 16);
+		rp16 ^= (rp16 >> 8);
+		rp16 &= 0xff;
+	}
+
+	/*
+	 * we also need to calculate the row parity for rp0..rp3
+	 * This is present in par, because par is now
+	 * rp3 rp3 rp2 rp2 in little endian and
+	 * rp2 rp2 rp3 rp3 in big endian
+	 * as well as
+	 * rp1 rp0 rp1 rp0 in little endian and
+	 * rp0 rp1 rp0 rp1 in big endian
+	 * First calculate rp2 and rp3
+	 */
+#ifdef __BIG_ENDIAN
+	rp2 = (par >> 16);
+	rp2 ^= (rp2 >> 8);
+	rp2 &= 0xff;
+	rp3 = par & 0xffff;
+	rp3 ^= (rp3 >> 8);
+	rp3 &= 0xff;
+#else
+	rp3 = (par >> 16);
+	rp3 ^= (rp3 >> 8);
+	rp3 &= 0xff;
+	rp2 = par & 0xffff;
+	rp2 ^= (rp2 >> 8);
+	rp2 &= 0xff;
+#endif
+
+	/* reduce par to 16 bits then calculate rp1 and rp0 */
+	par ^= (par >> 16);
+#ifdef __BIG_ENDIAN
+	rp0 = (par >> 8) & 0xff;
+	rp1 = (par & 0xff);
+#else
+	rp1 = (par >> 8) & 0xff;
+	rp0 = (par & 0xff);
+#endif
+
+	/* finally reduce par to 8 bits */
+	par ^= (par >> 8);
+	par &= 0xff;
+
+	/*
+	 * and calculate rp5..rp15..rp17
+	 * note that par = rp4 ^ rp5 and due to the commutative property
+	 * of the ^ operator we can say:
+	 * rp5 = (par ^ rp4);
+	 * The & 0xff seems superfluous, but benchmarking learned that
+	 * leaving it out gives slightly worse results. No idea why, probably
+	 * it has to do with the way the pipeline in pentium is organized.
+	 */
+	rp5 = (par ^ rp4) & 0xff;
+	rp7 = (par ^ rp6) & 0xff;
+	rp9 = (par ^ rp8) & 0xff;
+	rp11 = (par ^ rp10) & 0xff;
+	rp13 = (par ^ rp12) & 0xff;
+	rp15 = (par ^ rp14) & 0xff;
+	if (eccsize_mult == 2)
+		rp17 = (par ^ rp16) & 0xff;
+
+	/*
+	 * Finally calculate the ECC bits.
+	 * Again here it might seem that there are performance optimisations
+	 * possible, but benchmarks showed that on the system this is developed
+	 * the code below is the fastest
+	 */
+	if (sm_order) {
+		code[0] = (invparity[rp7] << 7) | (invparity[rp6] << 6) |
+			  (invparity[rp5] << 5) | (invparity[rp4] << 4) |
+			  (invparity[rp3] << 3) | (invparity[rp2] << 2) |
+			  (invparity[rp1] << 1) | (invparity[rp0]);
+		code[1] = (invparity[rp15] << 7) | (invparity[rp14] << 6) |
+			  (invparity[rp13] << 5) | (invparity[rp12] << 4) |
+			  (invparity[rp11] << 3) | (invparity[rp10] << 2) |
+			  (invparity[rp9] << 1) | (invparity[rp8]);
+	} else {
+		code[1] = (invparity[rp7] << 7) | (invparity[rp6] << 6) |
+			  (invparity[rp5] << 5) | (invparity[rp4] << 4) |
+			  (invparity[rp3] << 3) | (invparity[rp2] << 2) |
+			  (invparity[rp1] << 1) | (invparity[rp0]);
+		code[0] = (invparity[rp15] << 7) | (invparity[rp14] << 6) |
+			  (invparity[rp13] << 5) | (invparity[rp12] << 4) |
+			  (invparity[rp11] << 3) | (invparity[rp10] << 2) |
+			  (invparity[rp9] << 1) | (invparity[rp8]);
+	}
+
+	if (eccsize_mult == 1)
+		code[2] =
+		    (invparity[par & 0xf0] << 7) |
+		    (invparity[par & 0x0f] << 6) |
+		    (invparity[par & 0xcc] << 5) |
+		    (invparity[par & 0x33] << 4) |
+		    (invparity[par & 0xaa] << 3) |
+		    (invparity[par & 0x55] << 2) |
+		    3;
+	else
+		code[2] =
+		    (invparity[par & 0xf0] << 7) |
+		    (invparity[par & 0x0f] << 6) |
+		    (invparity[par & 0xcc] << 5) |
+		    (invparity[par & 0x33] << 4) |
+		    (invparity[par & 0xaa] << 3) |
+		    (invparity[par & 0x55] << 2) |
+		    (invparity[rp17] << 1) |
+		    (invparity[rp16] << 0);
+
+	return 0;
+}
+EXPORT_SYMBOL(ecc_sw_hamming_calculate);
+
+/**
+ * nand_ecc_sw_hamming_calculate - Calculate 3-byte ECC for 256/512-byte block
+ * @nand: NAND device
+ * @buf: Input buffer with raw data
+ * @code: Output buffer with ECC
+ */
+int nand_ecc_sw_hamming_calculate(struct nand_device *nand,
+				  const unsigned char *buf, unsigned char *code)
+{
+	struct nand_ecc_sw_hamming_conf *engine_conf = nand->ecc.ctx.priv;
+	unsigned int step_size = nand->ecc.ctx.conf.step_size;
+	bool sm_order = engine_conf ? engine_conf->sm_order : false;
+
+	return ecc_sw_hamming_calculate(buf, step_size, code, sm_order);
+}
+EXPORT_SYMBOL(nand_ecc_sw_hamming_calculate);
+
+int ecc_sw_hamming_correct(unsigned char *buf, unsigned char *read_ecc,
+			   unsigned char *calc_ecc, unsigned int step_size,
+			   bool sm_order)
+{
+	const u32 eccsize_mult = step_size >> 8;
+	unsigned char b0, b1, b2, bit_addr;
+	unsigned int byte_addr;
+
+	/*
+	 * b0 to b2 indicate which bit is faulty (if any)
+	 * we might need the xor result  more than once,
+	 * so keep them in a local var
+	*/
+	if (sm_order) {
+		b0 = read_ecc[0] ^ calc_ecc[0];
+		b1 = read_ecc[1] ^ calc_ecc[1];
+	} else {
+		b0 = read_ecc[1] ^ calc_ecc[1];
+		b1 = read_ecc[0] ^ calc_ecc[0];
+	}
+
+	b2 = read_ecc[2] ^ calc_ecc[2];
+
+	/* check if there are any bitfaults */
+
+	/* repeated if statements are slightly more efficient than switch ... */
+	/* ordered in order of likelihood */
+
+	if ((b0 | b1 | b2) == 0)
+		return 0;	/* no error */
+
+	if ((((b0 ^ (b0 >> 1)) & 0x55) == 0x55) &&
+	    (((b1 ^ (b1 >> 1)) & 0x55) == 0x55) &&
+	    ((eccsize_mult == 1 && ((b2 ^ (b2 >> 1)) & 0x54) == 0x54) ||
+	     (eccsize_mult == 2 && ((b2 ^ (b2 >> 1)) & 0x55) == 0x55))) {
+	/* single bit error */
+		/*
+		 * rp17/rp15/13/11/9/7/5/3/1 indicate which byte is the faulty
+		 * byte, cp 5/3/1 indicate the faulty bit.
+		 * A lookup table (called addressbits) is used to filter
+		 * the bits from the byte they are in.
+		 * A marginal optimisation is possible by having three
+		 * different lookup tables.
+		 * One as we have now (for b0), one for b2
+		 * (that would avoid the >> 1), and one for b1 (with all values
+		 * << 4). However it was felt that introducing two more tables
+		 * hardly justify the gain.
+		 *
+		 * The b2 shift is there to get rid of the lowest two bits.
+		 * We could also do addressbits[b2] >> 1 but for the
+		 * performance it does not make any difference
+		 */
+		if (eccsize_mult == 1)
+			byte_addr = (addressbits[b1] << 4) + addressbits[b0];
+		else
+			byte_addr = (addressbits[b2 & 0x3] << 8) +
+				    (addressbits[b1] << 4) + addressbits[b0];
+		bit_addr = addressbits[b2 >> 2];
+		/* flip the bit */
+		buf[byte_addr] ^= (1 << bit_addr);
+		return 1;
+
+	}
+	/* count nr of bits; use table lookup, faster than calculating it */
+	if ((bitsperbyte[b0] + bitsperbyte[b1] + bitsperbyte[b2]) == 1)
+		return 1;	/* error in ECC data; no action needed */
+
+	pr_err("%s: uncorrectable ECC error\n", __func__);
+	return -EBADMSG;
+}
+EXPORT_SYMBOL(ecc_sw_hamming_correct);
+
+/**
+ * nand_ecc_sw_hamming_correct - Detect and correct bit error(s)
+ * @nand: NAND device
+ * @buf: Raw data read from the chip
+ * @read_ecc: ECC bytes read from the chip
+ * @calc_ecc: ECC calculated from the raw data
+ *
+ * Detect and correct up to 1 bit error per 256/512-byte block.
+ */
+int nand_ecc_sw_hamming_correct(struct nand_device *nand, unsigned char *buf,
+				unsigned char *read_ecc,
+				unsigned char *calc_ecc)
+{
+	struct nand_ecc_sw_hamming_conf *engine_conf = nand->ecc.ctx.priv;
+	unsigned int step_size = nand->ecc.ctx.conf.step_size;
+	bool sm_order = engine_conf ? engine_conf->sm_order : false;
+
+	return ecc_sw_hamming_correct(buf, read_ecc, calc_ecc, step_size,
+				      sm_order);
+}
+EXPORT_SYMBOL(nand_ecc_sw_hamming_correct);
+
+int nand_ecc_sw_hamming_init_ctx(struct nand_device *nand)
+{
+	struct nand_ecc_props *conf = &nand->ecc.ctx.conf;
+	struct nand_ecc_sw_hamming_conf *engine_conf;
+	struct mtd_info *mtd = nanddev_to_mtd(nand);
+	int ret;
+
+	if (!mtd->ooblayout) {
+		switch (mtd->oobsize) {
+		case 8:
+		case 16:
+			mtd_set_ooblayout(mtd, nand_get_small_page_ooblayout());
+			break;
+		case 64:
+		case 128:
+			mtd_set_ooblayout(mtd,
+					  nand_get_large_page_hamming_ooblayout());
+			break;
+		default:
+			return -ENOTSUPP;
+		}
+	}
+
+	conf->engine_type = NAND_ECC_ENGINE_TYPE_SOFT;
+	conf->algo = NAND_ECC_ALGO_HAMMING;
+	conf->step_size = nand->ecc.user_conf.step_size;
+	conf->strength = 1;
+
+	/* Use the strongest configuration by default */
+	if (conf->step_size != 256 && conf->step_size != 512)
+		conf->step_size = 256;
+
+	engine_conf = kzalloc(sizeof(*engine_conf), GFP_KERNEL);
+	if (!engine_conf)
+		return -ENOMEM;
+
+	ret = nand_ecc_init_req_tweaking(&engine_conf->req_ctx, nand);
+	if (ret)
+		goto free_engine_conf;
+
+	engine_conf->code_size = 3;
+	engine_conf->calc_buf = kzalloc(mtd->oobsize, GFP_KERNEL);
+	engine_conf->code_buf = kzalloc(mtd->oobsize, GFP_KERNEL);
+	if (!engine_conf->calc_buf || !engine_conf->code_buf) {
+		ret = -ENOMEM;
+		goto free_bufs;
+	}
+
+	nand->ecc.ctx.priv = engine_conf;
+	nand->ecc.ctx.nsteps = mtd->writesize / conf->step_size;
+	nand->ecc.ctx.total = nand->ecc.ctx.nsteps * engine_conf->code_size;
+
+	return 0;
+
+free_bufs:
+	nand_ecc_cleanup_req_tweaking(&engine_conf->req_ctx);
+	kfree(engine_conf->calc_buf);
+	kfree(engine_conf->code_buf);
+free_engine_conf:
+	kfree(engine_conf);
+
+	return ret;
+}
+EXPORT_SYMBOL(nand_ecc_sw_hamming_init_ctx);
+
+void nand_ecc_sw_hamming_cleanup_ctx(struct nand_device *nand)
+{
+	struct nand_ecc_sw_hamming_conf *engine_conf = nand->ecc.ctx.priv;
+
+	if (engine_conf) {
+		nand_ecc_cleanup_req_tweaking(&engine_conf->req_ctx);
+		kfree(engine_conf->calc_buf);
+		kfree(engine_conf->code_buf);
+		kfree(engine_conf);
+	}
+}
+EXPORT_SYMBOL(nand_ecc_sw_hamming_cleanup_ctx);
+
+static int nand_ecc_sw_hamming_prepare_io_req(struct nand_device *nand,
+					      struct nand_page_io_req *req)
+{
+	struct nand_ecc_sw_hamming_conf *engine_conf = nand->ecc.ctx.priv;
+	struct mtd_info *mtd = nanddev_to_mtd(nand);
+	int eccsize = nand->ecc.ctx.conf.step_size;
+	int eccbytes = engine_conf->code_size;
+	int eccsteps = nand->ecc.ctx.nsteps;
+	int total = nand->ecc.ctx.total;
+	u8 *ecccalc = engine_conf->calc_buf;
+	const u8 *data;
+	int i;
+
+	/* Nothing to do for a raw operation */
+	if (req->mode == MTD_OPS_RAW)
+		return 0;
+
+	/* This engine does not provide BBM/free OOB bytes protection */
+	if (!req->datalen)
+		return 0;
+
+	nand_ecc_tweak_req(&engine_conf->req_ctx, req);
+
+	/* No more preparation for page read */
+	if (req->type == NAND_PAGE_READ)
+		return 0;
+
+	/* Preparation for page write: derive the ECC bytes and place them */
+	for (i = 0, data = req->databuf.out;
+	     eccsteps;
+	     eccsteps--, i += eccbytes, data += eccsize)
+		nand_ecc_sw_hamming_calculate(nand, data, &ecccalc[i]);
+
+	return mtd_ooblayout_set_eccbytes(mtd, ecccalc, (void *)req->oobbuf.out,
+					  0, total);
+}
+
+static int nand_ecc_sw_hamming_finish_io_req(struct nand_device *nand,
+					     struct nand_page_io_req *req)
+{
+	struct nand_ecc_sw_hamming_conf *engine_conf = nand->ecc.ctx.priv;
+	struct mtd_info *mtd = nanddev_to_mtd(nand);
+	int eccsize = nand->ecc.ctx.conf.step_size;
+	int total = nand->ecc.ctx.total;
+	int eccbytes = engine_conf->code_size;
+	int eccsteps = nand->ecc.ctx.nsteps;
+	u8 *ecccalc = engine_conf->calc_buf;
+	u8 *ecccode = engine_conf->code_buf;
+	unsigned int max_bitflips = 0;
+	u8 *data = req->databuf.in;
+	int i, ret;
+
+	/* Nothing to do for a raw operation */
+	if (req->mode == MTD_OPS_RAW)
+		return 0;
+
+	/* This engine does not provide BBM/free OOB bytes protection */
+	if (!req->datalen)
+		return 0;
+
+	/* No more preparation for page write */
+	if (req->type == NAND_PAGE_WRITE) {
+		nand_ecc_restore_req(&engine_conf->req_ctx, req);
+		return 0;
+	}
+
+	/* Finish a page read: retrieve the (raw) ECC bytes*/
+	ret = mtd_ooblayout_get_eccbytes(mtd, ecccode, req->oobbuf.in, 0,
+					 total);
+	if (ret)
+		return ret;
+
+	/* Calculate the ECC bytes */
+	for (i = 0; eccsteps; eccsteps--, i += eccbytes, data += eccsize)
+		nand_ecc_sw_hamming_calculate(nand, data, &ecccalc[i]);
+
+	/* Finish a page read: compare and correct */
+	for (eccsteps = nand->ecc.ctx.nsteps, i = 0, data = req->databuf.in;
+	     eccsteps;
+	     eccsteps--, i += eccbytes, data += eccsize) {
+		int stat =  nand_ecc_sw_hamming_correct(nand, data,
+							&ecccode[i],
+							&ecccalc[i]);
+		if (stat < 0) {
+			mtd->ecc_stats.failed++;
+		} else {
+			mtd->ecc_stats.corrected += stat;
+			max_bitflips = max_t(unsigned int, max_bitflips, stat);
+		}
+	}
+
+	nand_ecc_restore_req(&engine_conf->req_ctx, req);
+
+	return max_bitflips;
+}
+
+static struct nand_ecc_engine_ops nand_ecc_sw_hamming_engine_ops = {
+	.init_ctx = nand_ecc_sw_hamming_init_ctx,
+	.cleanup_ctx = nand_ecc_sw_hamming_cleanup_ctx,
+	.prepare_io_req = nand_ecc_sw_hamming_prepare_io_req,
+	.finish_io_req = nand_ecc_sw_hamming_finish_io_req,
+};
+
+static struct nand_ecc_engine nand_ecc_sw_hamming_engine = {
+	.ops = &nand_ecc_sw_hamming_engine_ops,
+};
+
+struct nand_ecc_engine *nand_ecc_sw_hamming_get_engine(void)
+{
+	return &nand_ecc_sw_hamming_engine;
+}
+EXPORT_SYMBOL(nand_ecc_sw_hamming_get_engine);
+
+MODULE_LICENSE("GPL");
+MODULE_AUTHOR("Frans Meulenbroeks <fransmeulenbroeks@gmail.com>");
+MODULE_DESCRIPTION("NAND software Hamming ECC support");