u-boot/drivers/mtd/nand/nand_bch.c
Masahiro Yamada 6ae3900a86 mtd: nand: Rename nand.h into rawnand.h
This header was renamed to rawnand.h in Linux.

The following is the corresponding commit in Linux.

  commit d4092d76a4a4e57b65910899948a83cc8646c5a5
  Author: Boris Brezillon <boris.brezillon@free-electrons.com>
  Date:   Fri Aug 4 17:29:10 2017 +0200

      mtd: nand: Rename nand.h into rawnand.h

      We are planning to share more code between different NAND based
      devices (SPI NAND, OneNAND and raw NANDs), but before doing that
      we need to move the existing include/linux/mtd/nand.h file into
      include/linux/mtd/rawnand.h so we can later create a nand.h header
      containing all common structure and function prototypes.

Signed-off-by: Masahiro Yamada <yamada.masahiro@socionext.com>
2017-12-04 22:00:00 +09:00

231 lines
6.2 KiB
C

/*
* 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>
*
* SPDX-License-Identifier: GPL-2.0+
*/
#include <common.h>
/*#include <asm/io.h>*/
#include <linux/types.h>
#include <linux/bitops.h>
#include <linux/mtd/mtd.h>
#include <linux/mtd/rawnand.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_to_nand(mtd);
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_to_nand(mtd);
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 */
pr_debug("%s: corrected bitflip %u\n",
__func__, errloc[i]);
}
} else if (count < 0) {
printk(KERN_ERR "ecc unrecoverable error\n");
count = -EBADMSG;
}
return count;
}
/**
* nand_bch_init - [NAND Interface] Initialize NAND BCH error correction
* @mtd: MTD block structure
*
* 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)
{
struct nand_chip *nand = mtd_to_nand(mtd);
unsigned int m, t, eccsteps, i;
struct nand_ecclayout *layout = nand->ecc.layout;
struct nand_bch_control *nbc = NULL;
unsigned char *erased_page;
unsigned int eccsize = nand->ecc.size;
unsigned int eccbytes = nand->ecc.bytes;
unsigned int eccstrength = nand->ecc.strength;
if (!eccbytes && eccstrength) {
eccbytes = DIV_ROUND_UP(eccstrength * fls(8 * eccsize), 8);
nand->ecc.bytes = eccbytes;
}
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 (!layout) {
/* 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;
nand->ecc.layout = layout;
}
/* sanity checks */
if (8*(eccsize+eccbytes) >= (1 << m)) {
printk(KERN_WARNING "eccsize %u is too large\n", eccsize);
goto fail;
}
if (layout->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;
if (!eccstrength)
nand->ecc.strength = (eccbytes * 8) / fls(8 * eccsize);
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);
}
}