nand: Merge BCH code from Linux nand driver

[backport from linux commit 02f8c6aee8df3cdc935e9bdd4f2d020306035dbe]

This patch merges the BCH ECC algorithm from the 3.0 Linux kernel.
This enables U-Boot to support modern NAND flash chips that
require more than 1-bit of ECC in software.

Signed-off-by: Christian Hitz <christian.hitz@aizo.com>
Cc: Scott Wood <scottwood@freescale.com>
Signed-off-by: Scott Wood <scottwood@freescale.com>

3 files changed, 154 insertions, 7 deletions

diff --git a/include/linux/bch.h b/include/linux/bch.h
new file mode 100644
index 0000000000..295b4ef153
--- /dev/null
+++ b/include/linux/bch.h
@@ -0,0 +1,79 @@
+/*
+ * Generic binary BCH encoding/decoding library
+ *
+ * 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; if not, write to the Free Software Foundation, Inc., 51
+ * Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
+ *
+ * Copyright © 2011 Parrot S.A.
+ *
+ * Author: Ivan Djelic <ivan.djelic@parrot.com>
+ *
+ * Description:
+ *
+ * This library provides runtime configurable encoding/decoding of binary
+ * Bose-Chaudhuri-Hocquenghem (BCH) codes.
+*/
+#ifndef _BCH_H
+#define _BCH_H
+
+#include <linux/types.h>
+
+/**
+ * struct bch_control - BCH control structure
+ * @m:          Galois field order
+ * @n:          maximum codeword size in bits (= 2^m-1)
+ * @t:          error correction capability in bits
+ * @ecc_bits:   ecc exact size in bits, i.e. generator polynomial degree (<=m*t)
+ * @ecc_bytes:  ecc max size (m*t bits) in bytes
+ * @a_pow_tab:  Galois field GF(2^m) exponentiation lookup table
+ * @a_log_tab:  Galois field GF(2^m) log lookup table
+ * @mod8_tab:   remainder generator polynomial lookup tables
+ * @ecc_buf:    ecc parity words buffer
+ * @ecc_buf2:   ecc parity words buffer
+ * @xi_tab:     GF(2^m) base for solving degree 2 polynomial roots
+ * @syn:        syndrome buffer
+ * @cache:      log-based polynomial representation buffer
+ * @elp:        error locator polynomial
+ * @poly_2t:    temporary polynomials of degree 2t
+ */
+struct bch_control {
+	unsigned int    m;
+	unsigned int    n;
+	unsigned int    t;
+	unsigned int    ecc_bits;
+	unsigned int    ecc_bytes;
+/* private: */
+	uint16_t       *a_pow_tab;
+	uint16_t       *a_log_tab;
+	uint32_t       *mod8_tab;
+	uint32_t       *ecc_buf;
+	uint32_t       *ecc_buf2;
+	unsigned int   *xi_tab;
+	unsigned int   *syn;
+	int            *cache;
+	struct gf_poly *elp;
+	struct gf_poly *poly_2t[4];
+};
+
+struct bch_control *init_bch(int m, int t, unsigned int prim_poly);
+
+void free_bch(struct bch_control *bch);
+
+void encode_bch(struct bch_control *bch, const uint8_t *data,
+		unsigned int len, uint8_t *ecc);
+
+int decode_bch(struct bch_control *bch, const uint8_t *data, unsigned int len,
+	       const uint8_t *recv_ecc, const uint8_t *calc_ecc,
+	       const unsigned int *syn, unsigned int *errloc);
+
+#endif /* _BCH_H */
diff --git a/include/linux/mtd/nand.h b/include/linux/mtd/nand.h
index 1cdc7ae279..527d9ae03f 100644
--- a/include/linux/mtd/nand.h
+++ b/include/linux/mtd/nand.h
@@ -18,13 +18,6 @@
 #ifndef __LINUX_MTD_NAND_H
 #define __LINUX_MTD_NAND_H
 
-/* XXX U-BOOT XXX */
-#if 0
-#include <linux/wait.h>
-#include <linux/spinlock.h>
-#include <linux/mtd/mtd.h>
-#endif
-
 #include "config.h"
 
 #include "linux/mtd/compat.h"
@@ -132,6 +125,7 @@ typedef enum {
 	NAND_ECC_HW,
 	NAND_ECC_HW_SYNDROME,
 	NAND_ECC_HW_OOB_FIRST,
+	NAND_ECC_SOFT_BCH,
 } nand_ecc_modes_t;
 
 /*
@@ -308,6 +302,7 @@ struct nand_hw_control {
  * @prepad:	padding information for syndrome based ecc generators
  * @postpad:	padding information for syndrome based ecc generators
  * @layout:	ECC layout control struct pointer
+ * @priv:       pointer to private ecc control data
  * @hwctl:	function to control hardware ecc generator. Must only
  *		be provided if an hardware ECC is available
  * @calculate:	function for ecc calculation or readback from ecc hardware
@@ -328,6 +323,7 @@ struct nand_ecc_ctrl {
 	int			prepad;
 	int			postpad;
 	struct nand_ecclayout	*layout;
+	void			*priv;
 	void			(*hwctl)(struct mtd_info *mtd, int mode);
 	int			(*calculate)(struct mtd_info *mtd,
 					     const uint8_t *dat,
diff --git a/include/linux/mtd/nand_bch.h b/include/linux/mtd/nand_bch.h
new file mode 100644
index 0000000000..d8754dd8c8
--- /dev/null
+++ b/include/linux/mtd/nand_bch.h
@@ -0,0 +1,72 @@
+/*
+ * Copyright © 2011 Ivan Djelic <ivan.djelic@parrot.com>
+ *
+ * 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 file is the header for the NAND BCH ECC implementation.
+ */
+
+#ifndef __MTD_NAND_BCH_H__
+#define __MTD_NAND_BCH_H__
+
+struct mtd_info;
+struct nand_bch_control;
+
+#if defined(CONFIG_NAND_ECC_BCH)
+
+static inline int mtd_nand_has_bch(void) { return 1; }
+
+/*
+ * Calculate BCH ecc code
+ */
+int nand_bch_calculate_ecc(struct mtd_info *mtd, const u_char *dat,
+			   u_char *ecc_code);
+
+/*
+ * Detect and correct bit errors
+ */
+int nand_bch_correct_data(struct mtd_info *mtd, u_char *dat, u_char *read_ecc,
+			  u_char *calc_ecc);
+/*
+ * Initialize BCH encoder/decoder
+ */
+struct nand_bch_control *
+nand_bch_init(struct mtd_info *mtd, unsigned int eccsize,
+	      unsigned int eccbytes, struct nand_ecclayout **ecclayout);
+/*
+ * Release BCH encoder/decoder resources
+ */
+void nand_bch_free(struct nand_bch_control *nbc);
+
+#else /* !CONFIG_NAND_ECC_BCH */
+
+static inline int mtd_nand_has_bch(void) { return 0; }
+
+static inline int
+nand_bch_calculate_ecc(struct mtd_info *mtd, const u_char *dat,
+		       u_char *ecc_code)
+{
+	return -1;
+}
+
+static inline int
+nand_bch_correct_data(struct mtd_info *mtd, unsigned char *buf,
+		      unsigned char *read_ecc, unsigned char *calc_ecc)
+{
+	return -1;
+}
+
+static inline struct nand_bch_control *
+nand_bch_init(struct mtd_info *mtd, unsigned int eccsize,
+	      unsigned int eccbytes, struct nand_ecclayout **ecclayout)
+{
+	return NULL;
+}
+
+static inline void nand_bch_free(struct nand_bch_control *nbc) {}
+
+#endif /* CONFIG_NAND_ECC_BCH */
+
+#endif /* __MTD_NAND_BCH_H__ */