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mtd: nand: omap: add support for BCH16_ECC - NAND driver updates

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This patch add support for BCH16_ECC to omap_gpmc driver.

*need to BCH16 ECC scheme*
With newer SLC Flash technologies and MLC NAND, and large densities, pagesizes
Flash devices have become more suspectible to bit-flips. Thus stronger
ECC schemes are required for protecting the data.
But stronger ECC schemes have come with larger-sized ECC syndromes which require
more space in OOB/Spare. This puts constrains like;
(a) BCH16_ECC can correct 16 bit-flips per 512Bytes of data.
(b) BCH16_ECC generates 26-bytes of ECC syndrome / 512B.
Due to (b) this scheme can only be used with NAND devices which have enough
OOB to satisfy following equation:
OOBsize per page >= 26 * (page-size / 512)

Signed-off-by: Pekon Gupta <pekon@ti.com>
This commit is contained in:
pekon gupta 2014-06-02 17:14:42 +05:30 committed by Tom Rini
parent 8d13a730de
commit 46840f66ca
2 changed files with 86 additions and 1 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

79
drivers/mtd/nand/omap_gpmc.c
View File

@ -224,6 +224,19 @@ static void omap_enable_hwecc(struct mtd_info *mtd, int32_t mode)
eccsize1 = 2; /* non-ECC bits in nibbles per sector */
}
break;
case OMAP_ECC_BCH16_CODE_HW:
ecc_algo = 0x1;
bch_type = 0x2;
if (mode == NAND_ECC_WRITE) {
bch_wrapmode = 0x01;
eccsize0 = 0; /* extra bits in nibbles per sector */
eccsize1 = 52; /* OOB bits in nibbles per sector */
} else {
bch_wrapmode = 0x01;
eccsize0 = 52; /* ECC bits in nibbles per sector */
eccsize1 = 0; /* non-ECC bits in nibbles per sector */
}
break;
default:
return;
}
@ -290,6 +303,29 @@ static int omap_calculate_ecc(struct mtd_info *mtd, const uint8_t *dat,
ptr--;
}
break;
case OMAP_ECC_BCH16_CODE_HW:
val = readl(&gpmc_cfg->bch_result_4_6[0].bch_result_x[2]);
ecc_code[i++] = (val >> 8) & 0xFF;
ecc_code[i++] = (val >> 0) & 0xFF;
val = readl(&gpmc_cfg->bch_result_4_6[0].bch_result_x[1]);
ecc_code[i++] = (val >> 24) & 0xFF;
ecc_code[i++] = (val >> 16) & 0xFF;
ecc_code[i++] = (val >> 8) & 0xFF;
ecc_code[i++] = (val >> 0) & 0xFF;
val = readl(&gpmc_cfg->bch_result_4_6[0].bch_result_x[0]);
ecc_code[i++] = (val >> 24) & 0xFF;
ecc_code[i++] = (val >> 16) & 0xFF;
ecc_code[i++] = (val >> 8) & 0xFF;
ecc_code[i++] = (val >> 0) & 0xFF;
for (j = 3; j >= 0; j--) {
val = readl(&gpmc_cfg->bch_result_0_3[0].bch_result_x[j]
);
ecc_code[i++] = (val >> 24) & 0xFF;
ecc_code[i++] = (val >> 16) & 0xFF;
ecc_code[i++] = (val >> 8) & 0xFF;
ecc_code[i++] = (val >> 0) & 0xFF;
}
break;
default:
return -EINVAL;
}
@ -308,6 +344,8 @@ static int omap_calculate_ecc(struct mtd_info *mtd, const uint8_t *dat,
case OMAP_ECC_BCH8_CODE_HW:
ecc_code[chip->ecc.bytes - 1] = 0x00;
break;
case OMAP_ECC_BCH16_CODE_HW:
break;
default:
return -EINVAL;
}
@ -333,7 +371,7 @@ static int omap_correct_data_bch(struct mtd_info *mtd, uint8_t *dat,
struct omap_nand_info *info = chip->priv;
struct nand_ecc_ctrl *ecc = &chip->ecc;
uint32_t error_count = 0, error_max;
uint32_t error_loc[8];
uint32_t error_loc[ELM_MAX_ERROR_COUNT];
enum bch_level bch_type;
uint32_t i, ecc_flag = 0;
uint8_t count, err = 0;
@ -365,6 +403,10 @@ static int omap_correct_data_bch(struct mtd_info *mtd, uint8_t *dat,
bch_type = BCH_8_BIT;
omap_reverse_list(calc_ecc, ecc->bytes - 1);
break;
case OMAP_ECC_BCH16_CODE_HW:
bch_type = BCH_16_BIT;
omap_reverse_list(calc_ecc, ecc->bytes);
break;
default:
return -EINVAL;
}
@ -381,6 +423,9 @@ static int omap_correct_data_bch(struct mtd_info *mtd, uint8_t *dat,
/* 14th byte in ECC is reserved to match ROM layout */
error_max = SECTOR_BYTES + (ecc->bytes - 1);
break;
case OMAP_ECC_BCH16_CODE_HW:
error_max = SECTOR_BYTES + ecc->bytes;
break;
default:
return -EINVAL;
}
@ -666,6 +711,38 @@ static int omap_select_ecc_scheme(struct nand_chip *nand,
return -EINVAL;
#endif
case OMAP_ECC_BCH16_CODE_HW:
#ifdef CONFIG_NAND_OMAP_ELM
debug("nand: using OMAP_ECC_BCH16_CODE_HW\n");
/* check ecc-scheme requirements before updating ecc info */
if ((26 * eccsteps) + BADBLOCK_MARKER_LENGTH > oobsize) {
printf("nand: error: insufficient OOB: require=%d\n", (
(26 * eccsteps) + BADBLOCK_MARKER_LENGTH));
return -EINVAL;
}
/* intialize ELM for ECC error detection */
elm_init();
/* populate ecc specific fields */
nand->ecc.mode = NAND_ECC_HW;
nand->ecc.size = SECTOR_BYTES;
nand->ecc.bytes = 26;
nand->ecc.strength = 16;
nand->ecc.hwctl = omap_enable_hwecc;
nand->ecc.correct = omap_correct_data_bch;
nand->ecc.calculate = omap_calculate_ecc;
nand->ecc.read_page = omap_read_page_bch;
/* define ecc-layout */
ecclayout->eccbytes = nand->ecc.bytes * eccsteps;
for (i = 0; i < ecclayout->eccbytes; i++)
ecclayout->eccpos[i] = i + BADBLOCK_MARKER_LENGTH;
ecclayout->oobfree[0].offset = i + BADBLOCK_MARKER_LENGTH;
ecclayout->oobfree[0].length = oobsize - nand->ecc.bytes -
BADBLOCK_MARKER_LENGTH;
break;
#else
printf("nand: error: CONFIG_NAND_OMAP_ELM required for ECC\n");
return -EINVAL;
#endif
default:
debug("nand: error: ecc scheme not enabled or supported\n");
return -EINVAL;

8
include/linux/mtd/omap_gpmc.h
View File

@ -27,6 +27,8 @@ enum omap_ecc {
OMAP_ECC_BCH8_CODE_HW_DETECTION_SW,
/* 8-bit ECC calculation by GPMC, Error detection by ELM */
OMAP_ECC_BCH8_CODE_HW,
/* 16-bit ECC calculation by GPMC, Error detection by ELM */
OMAP_ECC_BCH16_CODE_HW,
};
struct gpmc_cs {
@ -47,6 +49,10 @@ struct bch_res_0_3 {
u32 bch_result_x[4];
};
struct bch_res_4_6 {
u32 bch_result_x[3];
};
struct gpmc {
u8 res1[0x10];
u32 sysconfig; /* 0x10 */
@ -77,6 +83,8 @@ struct gpmc {
u32 testmomde_ctrl; /* 0x230 */
u8 res8[12]; /* 0x234 */
struct bch_res_0_3 bch_result_0_3[GPMC_MAX_SECTORS]; /* 0x240,0x250, */
u8 res9[16 * 4]; /* 0x2C0 - 0x2FF */
struct bch_res_4_6 bch_result_4_6[GPMC_MAX_SECTORS]; /* 0x300,0x310, */
};
/* Used for board specific gpmc initialization */