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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
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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 */