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mtd: nand: mxs_nand: add minimal ECC support

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Add support for minimum ECC strength supported by the NAND chip.
This aligns with the behavior when using the fsl,use-minimum-ecc
device tree property in Linux.

Signed-off-by: Stefan Agner <stefan.agner@toradex.com>
This commit is contained in:
Stefan Agner 2018-06-22 17:19:51 +02:00 • committed by Stefano Babic
parent 5c69dd0730
commit 984df7add1
2 changed files with 66 additions and 14 deletions
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8
drivers/mtd/nand/Kconfig
View file

@ -152,6 +152,14 @@ config NAND_MXS
This enables NAND driver for the NAND flash controller on the
MXS processors.
if NAND_MXS
config NAND_MXS_USE_MINIMUM_ECC
bool "Use minimum ECC strength supported by the controller"
default false
endif
config NAND_ZYNQ
bool "Support for Zynq Nand controller"
select SYS_NAND_SELF_INIT

72
drivers/mtd/nand/mxs_nand.c
View file

@ -15,6 +15,7 @@
#include <common.h>
#include <linux/mtd/mtd.h>
#include <linux/mtd/rawnand.h>
#include <linux/sizes.h>
#include <linux/types.h>
#include <malloc.h>
#include <nand.h>
@ -211,11 +212,52 @@ static inline int mxs_nand_calc_mark_offset(struct bch_geometry *geo,
return 0;
}
static inline unsigned int mxs_nand_max_ecc_strength_supported(void)
{
/* Refer to Chapter 17 for i.MX6DQ, Chapter 18 for i.MX6SX */
if (is_mx6sx() || is_mx7())
return 62;
else
return 40;
}
static inline int mxs_nand_calc_ecc_layout_by_info(struct bch_geometry *geo,
struct mtd_info *mtd)
{
struct nand_chip *chip = mtd_to_nand(mtd);
if (!(chip->ecc_strength_ds > 0 && chip->ecc_step_ds > 0))
return -ENOTSUPP;
switch (chip->ecc_step_ds) {
case SZ_512:
geo->gf_len = 13;
break;
case SZ_1K:
geo->gf_len = 14;
break;
default:
return -EINVAL;
}
geo->ecc_chunk_size = chip->ecc_step_ds;
geo->ecc_strength = round_up(chip->ecc_strength_ds, 2);
/* Keep the C >= O */
if (geo->ecc_chunk_size < mtd->oobsize)
return -EINVAL;
if (geo->ecc_strength > mxs_nand_max_ecc_strength_supported())
return -EINVAL;
geo->ecc_chunk_count = mtd->writesize / geo->ecc_chunk_size;
return 0;
}
static inline int mxs_nand_calc_ecc_layout(struct bch_geometry *geo,
struct mtd_info *mtd)
{
unsigned int max_ecc_strength_supported;
/* The default for the length of Galois Field. */
geo->gf_len = 13;
@ -235,12 +277,6 @@ static inline int mxs_nand_calc_ecc_layout(struct bch_geometry *geo,
geo->ecc_chunk_count = mtd->writesize / geo->ecc_chunk_size;
/* Refer to Chapter 17 for i.MX6DQ, Chapter 18 for i.MX6SX */
if (is_mx6sx() || is_mx7())
max_ecc_strength_supported = 62;
else
max_ecc_strength_supported = 40;
/*
* Determine the ECC layout with the formula:
* ECC bits per chunk = (total page spare data bits) /
@ -252,10 +288,8 @@ static inline int mxs_nand_calc_ecc_layout(struct bch_geometry *geo,
geo->ecc_strength = ((mtd->oobsize - MXS_NAND_METADATA_SIZE) * 8)
/ (geo->gf_len * geo->ecc_chunk_count);
geo->ecc_strength = min(round_down(geo->ecc_strength, 2), max_ecc_strength_supported);
if (mxs_nand_calc_mark_offset(geo, mtd->writesize) < 0)
return -EINVAL;
geo->ecc_strength = min(round_down(geo->ecc_strength, 2),
mxs_nand_max_ecc_strength_supported());
return 0;
}
@ -1006,9 +1040,19 @@ int mxs_nand_setup_ecc(struct mtd_info *mtd)
struct bch_geometry *geo = &nand_info->bch_geometry;
struct mxs_bch_regs *bch_regs = (struct mxs_bch_regs *)MXS_BCH_BASE;
uint32_t tmp;
int ret = -ENOTSUPP;
if (mxs_nand_calc_ecc_layout(geo, mtd))
return -EINVAL;
#ifdef CONFIG_NAND_MXS_USE_MINIMUM_ECC
ret = mxs_nand_calc_ecc_layout_by_info(geo, mtd);
#endif
if (ret == -ENOTSUPP)
ret = mxs_nand_calc_ecc_layout(geo, mtd);
if (ret)
return ret;
mxs_nand_calc_mark_offset(geo, mtd->writesize);
/* Configure BCH and set NFC geometry */
mxs_reset_block(&bch_regs->hw_bch_ctrl_reg);