diff options
| -rw-r--r-- | drivers/mtd/nand/Kconfig | 15 | ||||
| -rw-r--r-- | drivers/mtd/nand/Makefile | 1 | ||||
| -rw-r--r-- | drivers/mtd/nand/nand_base.c | 40 | ||||
| -rw-r--r-- | drivers/mtd/nand/nand_bch.c | 243 | ||||
| -rw-r--r-- | include/linux/mtd/nand.h | 3 | ||||
| -rw-r--r-- | include/linux/mtd/nand_bch.h | 72 |
6 files changed, 373 insertions, 1 deletions
diff --git a/drivers/mtd/nand/Kconfig b/drivers/mtd/nand/Kconfig index c895922..78205ac 100644 --- a/drivers/mtd/nand/Kconfig +++ b/drivers/mtd/nand/Kconfig @@ -31,6 +31,21 @@ config MTD_NAND_VERIFY_WRITE device thinks the write was successful, a bit could have been flipped accidentally due to device wear or something else. +config MTD_NAND_BCH + tristate + select BCH + depends on MTD_NAND_ECC_BCH + default MTD_NAND + +config MTD_NAND_ECC_BCH + bool "Support software BCH ECC" + default n + help + This enables support for software BCH error correction. Binary BCH + codes are more powerful and cpu intensive than traditional Hamming + ECC codes. They are used with NAND devices requiring more than 1 bit + of error correction. + config MTD_SM_COMMON tristate default n diff --git a/drivers/mtd/nand/Makefile b/drivers/mtd/nand/Makefile index 8ad6fae..5745d83 100644 --- a/drivers/mtd/nand/Makefile +++ b/drivers/mtd/nand/Makefile @@ -4,6 +4,7 @@ obj-$(CONFIG_MTD_NAND) += nand.o obj-$(CONFIG_MTD_NAND_ECC) += nand_ecc.o +obj-$(CONFIG_MTD_NAND_BCH) += nand_bch.o obj-$(CONFIG_MTD_NAND_IDS) += nand_ids.o obj-$(CONFIG_MTD_SM_COMMON) += sm_common.o diff --git a/drivers/mtd/nand/nand_base.c b/drivers/mtd/nand/nand_base.c index da76040..85cfc06 100644 --- a/drivers/mtd/nand/nand_base.c +++ b/drivers/mtd/nand/nand_base.c @@ -42,6 +42,7 @@ #include <linux/mtd/mtd.h> #include <linux/mtd/nand.h> #include <linux/mtd/nand_ecc.h> +#include <linux/mtd/nand_bch.h> #include <linux/interrupt.h> #include <linux/bitops.h> #include <linux/leds.h> @@ -3248,7 +3249,7 @@ 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; @@ -3351,6 +3352,40 @@ 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"); + BUG(); + } + 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"); + BUG(); + } + break; + case NAND_ECC_NONE: printk(KERN_WARNING "NAND_ECC_NONE selected by board driver. " "This is not recommended !!\n"); @@ -3501,6 +3536,9 @@ 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); diff --git a/drivers/mtd/nand/nand_bch.c b/drivers/mtd/nand/nand_bch.c new file mode 100644 index 0000000..0f931e7 --- /dev/null +++ b/drivers/mtd/nand/nand_bch.c @@ -0,0 +1,243 @@ +/* + * 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 <linux/types.h> +#include <linux/kernel.h> +#include <linux/module.h> +#include <linux/slab.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> + +/** + * 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; +} +EXPORT_SYMBOL(nand_bch_calculate_ecc); + +/** + * 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 */ + + DEBUG(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; +} +EXPORT_SYMBOL(nand_bch_correct_data); + +/** + * 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; +} +EXPORT_SYMBOL(nand_bch_init); + +/** + * 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); + } +} +EXPORT_SYMBOL(nand_bch_free); + +MODULE_LICENSE("GPL"); +MODULE_AUTHOR("Ivan Djelic <ivan.djelic@parrot.com>"); +MODULE_DESCRIPTION("NAND software BCH ECC support"); diff --git a/include/linux/mtd/nand.h b/include/linux/mtd/nand.h index 1f489b2..ae67ef5 100644 --- a/include/linux/mtd/nand.h +++ b/include/linux/mtd/nand.h @@ -140,6 +140,7 @@ typedef enum { NAND_ECC_HW, NAND_ECC_HW_SYNDROME, NAND_ECC_HW_OOB_FIRST, + NAND_ECC_SOFT_BCH, } nand_ecc_modes_t; /* @@ -339,6 +340,7 @@ 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 @@ -362,6 +364,7 @@ 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, uint8_t *ecc_code); diff --git a/include/linux/mtd/nand_bch.h b/include/linux/mtd/nand_bch.h new file mode 100644 index 0000000..74acf53 --- /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_MTD_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_MTD_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_MTD_NAND_ECC_BCH */ + +#endif /* __MTD_NAND_BCH_H__ */ |
