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>
This commit is contained in:
Christian Hitz 2011-10-12 09:31:59 +02:00 committed by Scott Wood
parent 4d2aee2b36
commit 4c6de8560c
8 changed files with 1788 additions and 8 deletions

View file

@ -41,6 +41,7 @@ COBJS-y += nand_util.o
endif
COBJS-y += nand_ecc.o
COBJS-y += nand_base.o
COBJS-$(CONFIG_NAND_ECC_BCH) += nand_bch.o
COBJS-$(CONFIG_NAND_ATMEL) += atmel_nand.o
COBJS-$(CONFIG_DRIVER_NAND_BFIN) += bfin_nand.o

View file

@ -43,6 +43,7 @@
#include <linux/mtd/mtd.h>
#include <linux/mtd/nand.h>
#include <linux/mtd/nand_ecc.h>
#include <linux/mtd/nand_bch.h>
#ifdef CONFIG_MTD_PARTITIONS
#include <linux/mtd/partitions.h>
@ -2763,7 +2764,7 @@ int nand_scan_tail(struct mtd_info *mtd)
/*
* If no default placement scheme is given, select an appropriate one
*/
if (!chip->ecc.layout) {
if (!chip->ecc.layout && (chip->ecc.mode != NAND_ECC_SOFT_BCH)) {
switch (mtd->oobsize) {
case 8:
chip->ecc.layout = &nand_oob_8;
@ -2864,6 +2865,39 @@ int nand_scan_tail(struct mtd_info *mtd)
chip->ecc.bytes = 3;
break;
case NAND_ECC_SOFT_BCH:
if (!mtd_nand_has_bch()) {
printk(KERN_WARNING "CONFIG_MTD_ECC_BCH not enabled\n");
return -EINVAL;
}
chip->ecc.calculate = nand_bch_calculate_ecc;
chip->ecc.correct = nand_bch_correct_data;
chip->ecc.read_page = nand_read_page_swecc;
chip->ecc.read_subpage = nand_read_subpage;
chip->ecc.write_page = nand_write_page_swecc;
chip->ecc.read_page_raw = nand_read_page_raw;
chip->ecc.write_page_raw = nand_write_page_raw;
chip->ecc.read_oob = nand_read_oob_std;
chip->ecc.write_oob = nand_write_oob_std;
/*
* Board driver should supply ecc.size and ecc.bytes values to
* select how many bits are correctable; see nand_bch_init()
* for details.
* Otherwise, default to 4 bits for large page devices
*/
if (!chip->ecc.size && (mtd->oobsize >= 64)) {
chip->ecc.size = 512;
chip->ecc.bytes = 7;
}
chip->ecc.priv = nand_bch_init(mtd,
chip->ecc.size,
chip->ecc.bytes,
&chip->ecc.layout);
if (!chip->ecc.priv)
printk(KERN_WARNING "BCH ECC initialization failed!\n");
break;
case NAND_ECC_NONE:
printk(KERN_WARNING "NAND_ECC_NONE selected by board driver. "
"This is not recommended !!\n");
@ -2989,6 +3023,9 @@ void nand_release(struct mtd_info *mtd)
{
struct nand_chip *chip = mtd->priv;
if (chip->ecc.mode == NAND_ECC_SOFT_BCH)
nand_bch_free((struct nand_bch_control *)chip->ecc.priv);
#ifdef CONFIG_MTD_PARTITIONS
/* Deregister partitions */
del_mtd_partitions(mtd);

236
drivers/mtd/nand/nand_bch.c Normal file
View file

@ -0,0 +1,236 @@
/*
* This file provides ECC correction for more than 1 bit per block of data,
* using binary BCH codes. It relies on the generic BCH library lib/bch.c.
*
* Copyright © 2011 Ivan Djelic <ivan.djelic@parrot.com>
*
* This file is free software; you can redistribute it and/or modify it
* under the terms of the GNU General Public License as published by the
* Free Software Foundation; either version 2 or (at your option) any
* later version.
*
* This file 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 file; if not, write to the Free Software Foundation, Inc.,
* 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA.
*/
#include <common.h>
/*#include <asm/io.h>*/
#include <linux/types.h>
#include <linux/bitops.h>
#include <linux/mtd/mtd.h>
#include <linux/mtd/nand.h>
#include <linux/mtd/nand_bch.h>
#include <linux/bch.h>
#include <malloc.h>
/**
* struct nand_bch_control - private NAND BCH control structure
* @bch: BCH control structure
* @ecclayout: private ecc layout for this BCH configuration
* @errloc: error location array
* @eccmask: XOR ecc mask, allows erased pages to be decoded as valid
*/
struct nand_bch_control {
struct bch_control *bch;
struct nand_ecclayout ecclayout;
unsigned int *errloc;
unsigned char *eccmask;
};
/**
* nand_bch_calculate_ecc - [NAND Interface] Calculate ECC for data block
* @mtd: MTD block structure
* @buf: input buffer with raw data
* @code: output buffer with ECC
*/
int nand_bch_calculate_ecc(struct mtd_info *mtd, const unsigned char *buf,
unsigned char *code)
{
const struct nand_chip *chip = mtd->priv;
struct nand_bch_control *nbc = chip->ecc.priv;
unsigned int i;
memset(code, 0, chip->ecc.bytes);
encode_bch(nbc->bch, buf, chip->ecc.size, code);
/* apply mask so that an erased page is a valid codeword */
for (i = 0; i < chip->ecc.bytes; i++)
code[i] ^= nbc->eccmask[i];
return 0;
}
/**
* nand_bch_correct_data - [NAND Interface] Detect and correct bit error(s)
* @mtd: MTD block structure
* @buf: raw data read from the chip
* @read_ecc: ECC from the chip
* @calc_ecc: the ECC calculated from raw data
*
* Detect and correct bit errors for a data byte block
*/
int nand_bch_correct_data(struct mtd_info *mtd, unsigned char *buf,
unsigned char *read_ecc, unsigned char *calc_ecc)
{
const struct nand_chip *chip = mtd->priv;
struct nand_bch_control *nbc = chip->ecc.priv;
unsigned int *errloc = nbc->errloc;
int i, count;
count = decode_bch(nbc->bch, NULL, chip->ecc.size, read_ecc, calc_ecc,
NULL, errloc);
if (count > 0) {
for (i = 0; i < count; i++) {
if (errloc[i] < (chip->ecc.size*8))
/* error is located in data, correct it */
buf[errloc[i] >> 3] ^= (1 << (errloc[i] & 7));
/* else error in ecc, no action needed */
MTDDEBUG(MTD_DEBUG_LEVEL0, "%s: corrected bitflip %u\n",
__func__, errloc[i]);
}
} else if (count < 0) {
printk(KERN_ERR "ecc unrecoverable error\n");
count = -1;
}
return count;
}
/**
* nand_bch_init - [NAND Interface] Initialize NAND BCH error correction
* @mtd: MTD block structure
* @eccsize: ecc block size in bytes
* @eccbytes: ecc length in bytes
* @ecclayout: output default layout
*
* Returns:
* a pointer to a new NAND BCH control structure, or NULL upon failure
*
* Initialize NAND BCH error correction. Parameters @eccsize and @eccbytes
* are used to compute BCH parameters m (Galois field order) and t (error
* correction capability). @eccbytes should be equal to the number of bytes
* required to store m*t bits, where m is such that 2^m-1 > @eccsize*8.
*
* Example: to configure 4 bit correction per 512 bytes, you should pass
* @eccsize = 512 (thus, m=13 is the smallest integer such that 2^m-1 > 512*8)
* @eccbytes = 7 (7 bytes are required to store m*t = 13*4 = 52 bits)
*/
struct nand_bch_control *
nand_bch_init(struct mtd_info *mtd, unsigned int eccsize, unsigned int eccbytes,
struct nand_ecclayout **ecclayout)
{
unsigned int m, t, eccsteps, i;
struct nand_ecclayout *layout;
struct nand_bch_control *nbc = NULL;
unsigned char *erased_page;
if (!eccsize || !eccbytes) {
printk(KERN_WARNING "ecc parameters not supplied\n");
goto fail;
}
m = fls(1+8*eccsize);
t = (eccbytes*8)/m;
nbc = kzalloc(sizeof(*nbc), GFP_KERNEL);
if (!nbc)
goto fail;
nbc->bch = init_bch(m, t, 0);
if (!nbc->bch)
goto fail;
/* verify that eccbytes has the expected value */
if (nbc->bch->ecc_bytes != eccbytes) {
printk(KERN_WARNING "invalid eccbytes %u, should be %u\n",
eccbytes, nbc->bch->ecc_bytes);
goto fail;
}
eccsteps = mtd->writesize/eccsize;
/* if no ecc placement scheme was provided, build one */
if (!*ecclayout) {
/* handle large page devices only */
if (mtd->oobsize < 64) {
printk(KERN_WARNING "must provide an oob scheme for "
"oobsize %d\n", mtd->oobsize);
goto fail;
}
layout = &nbc->ecclayout;
layout->eccbytes = eccsteps*eccbytes;
/* reserve 2 bytes for bad block marker */
if (layout->eccbytes+2 > mtd->oobsize) {
printk(KERN_WARNING "no suitable oob scheme available "
"for oobsize %d eccbytes %u\n", mtd->oobsize,
eccbytes);
goto fail;
}
/* put ecc bytes at oob tail */
for (i = 0; i < layout->eccbytes; i++)
layout->eccpos[i] = mtd->oobsize-layout->eccbytes+i;
layout->oobfree[0].offset = 2;
layout->oobfree[0].length = mtd->oobsize-2-layout->eccbytes;
*ecclayout = layout;
}
/* sanity checks */
if (8*(eccsize+eccbytes) >= (1 << m)) {
printk(KERN_WARNING "eccsize %u is too large\n", eccsize);
goto fail;
}
if ((*ecclayout)->eccbytes != (eccsteps*eccbytes)) {
printk(KERN_WARNING "invalid ecc layout\n");
goto fail;
}
nbc->eccmask = kmalloc(eccbytes, GFP_KERNEL);
nbc->errloc = kmalloc(t*sizeof(*nbc->errloc), GFP_KERNEL);
if (!nbc->eccmask || !nbc->errloc)
goto fail;
/*
* compute and store the inverted ecc of an erased ecc block
*/
erased_page = kmalloc(eccsize, GFP_KERNEL);
if (!erased_page)
goto fail;
memset(erased_page, 0xff, eccsize);
memset(nbc->eccmask, 0, eccbytes);
encode_bch(nbc->bch, erased_page, eccsize, nbc->eccmask);
kfree(erased_page);
for (i = 0; i < eccbytes; i++)
nbc->eccmask[i] ^= 0xff;
return nbc;
fail:
nand_bch_free(nbc);
return NULL;
}
/**
* nand_bch_free - [NAND Interface] Release NAND BCH ECC resources
* @nbc: NAND BCH control structure
*/
void nand_bch_free(struct nand_bch_control *nbc)
{
if (nbc) {
free_bch(nbc->bch);
kfree(nbc->errloc);
kfree(nbc->eccmask);
kfree(nbc);
}
}

79
include/linux/bch.h Normal file
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@ -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 */

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@ -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,

View file

@ -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__ */

View file

@ -27,6 +27,7 @@ LIB = $(obj)libgeneric.o
ifndef CONFIG_SPL_BUILD
COBJS-$(CONFIG_ADDR_MAP) += addr_map.o
COBJS-$(CONFIG_BCH) += bch.o
COBJS-$(CONFIG_BZIP2) += bzlib.o
COBJS-$(CONFIG_BZIP2) += bzlib_crctable.o
COBJS-$(CONFIG_BZIP2) += bzlib_decompress.o

1358
lib/bch.c Normal file

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