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mtd: nand: add generic helpers to check, match, maximize ECC settings

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Driver are responsible for setting up ECC parameters correctly.
Those include:
  - Check if ECC parameters specified (usually by DT) are valid
  - Meet the chip's ECC requirement
  - Maximize ECC strength if NAND_ECC_MAXIMIZE flag is set

The logic can be generalized by factoring out common code.

This commit adds 3 helpers to the NAND framework:
nand_check_ecc_caps - Check if preset step_size and strength are valid
nand_match_ecc_req - Match the chip's requirement
nand_maximize_ecc - Maximize the ECC strength

To use the helpers above, a driver needs to provide:
  - Data array of supported ECC step size and strength
  - A hook that calculates ECC bytes from the combination of
    step_size and strength.

By using those helpers, code duplication among drivers will be
reduced.

Signed-off-by: Masahiro Yamada <yamada.masahiro@socionext.com>
Signed-off-by: Boris Brezillon <boris.brezillon@free-electrons.com>
This commit is contained in:
Masahiro Yamada 2017-06-07 20:52:10 +09:00 • committed by Boris Brezillon
parent df8b97024e
commit 2c8f8afa7f
2 changed files with 253 additions and 0 deletions
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33
include/linux/mtd/nand.h
View file

@ -481,6 +481,30 @@ static inline void nand_hw_control_init(struct nand_hw_control *nfc)
init_waitqueue_head(&nfc->wq);
}
/**
* struct nand_ecc_step_info - ECC step information of ECC engine
* @stepsize: data bytes per ECC step
* @strengths: array of supported strengths
* @nstrengths: number of supported strengths
*/
struct nand_ecc_step_info {
int stepsize;
const int *strengths;
int nstrengths;
};
/**
* struct nand_ecc_caps - capability of ECC engine
* @stepinfos: array of ECC step information
* @nstepinfos: number of ECC step information
* @calc_ecc_bytes: driver's hook to calculate ECC bytes per step
*/
struct nand_ecc_caps {
const struct nand_ecc_step_info *stepinfos;
int nstepinfos;
int (*calc_ecc_bytes)(int step_size, int strength);
};
/**
* struct nand_ecc_ctrl - Control structure for ECC
* @mode: ECC mode
@ -1246,6 +1270,15 @@ int nand_check_erased_ecc_chunk(void *data, int datalen,
void *extraoob, int extraooblen,
int threshold);
int nand_check_ecc_caps(struct nand_chip *chip,
const struct nand_ecc_caps *caps, int oobavail);
int nand_match_ecc_req(struct nand_chip *chip,
const struct nand_ecc_caps *caps, int oobavail);
int nand_maximize_ecc(struct nand_chip *chip,
const struct nand_ecc_caps *caps, int oobavail);
/* Default write_oob implementation */
int nand_write_oob_std(struct mtd_info *mtd, struct nand_chip *chip, int page);