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mtd: nand: move nand_check_erased_ecc_chunk() to nand/core

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The check function for bitflips in erased blocks will be needed
by the Realtek ECC engine driver (which is currently under
development). Right now it is located in raw/nand_base.c.
While this is sufficient for the current usecases, there is
no real dependency for an ECC engine on the raw nand library.

Move the function over to a more generic place in core library.

Suggested-by: Miquel Raynal <miquel.raynal@bootlin.com>
Signed-off-by: Markus Stockhausen <markus.stockhausen@gmx.de>
Signed-off-by: Miquel Raynal <miquel.raynal@bootlin.com>
This commit is contained in:
Markus Stockhausen 2025-09-10 14:32:58 -04:00 committed by Miquel Raynal
parent 01adc8207c
commit 6b88293aae
4 changed files with 136 additions and 136 deletions
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131
drivers/mtd/nand/core.c
View File

@ -12,6 +12,137 @@
#include <linux/module.h>
#include <linux/mtd/nand.h>
/**
* nand_check_erased_buf - check if a buffer contains (almost) only 0xff data
* @buf: buffer to test
* @len: buffer length
* @bitflips_threshold: maximum number of bitflips
*
* Check if a buffer contains only 0xff, which means the underlying region
* has been erased and is ready to be programmed.
* The bitflips_threshold specify the maximum number of bitflips before
* considering the region is not erased.
* Note: The logic of this function has been extracted from the memweight
* implementation, except that nand_check_erased_buf function exit before
* testing the whole buffer if the number of bitflips exceed the
* bitflips_threshold value.
*
* Returns a positive number of bitflips less than or equal to
* bitflips_threshold, or -ERROR_CODE for bitflips in excess of the
* threshold.
*/
static int nand_check_erased_buf(void *buf, int len, int bitflips_threshold)
{
const unsigned char *bitmap = buf;
int bitflips = 0;
int weight;
for (; len && ((uintptr_t)bitmap) % sizeof(long);
len--, bitmap++) {
weight = hweight8(*bitmap);
bitflips += BITS_PER_BYTE - weight;
if (unlikely(bitflips > bitflips_threshold))
return -EBADMSG;
}
for (; len >= sizeof(long);
len -= sizeof(long), bitmap += sizeof(long)) {
unsigned long d = *((unsigned long *)bitmap);
if (d == ~0UL)
continue;
weight = hweight_long(d);
bitflips += BITS_PER_LONG - weight;
if (unlikely(bitflips > bitflips_threshold))
return -EBADMSG;
}
for (; len > 0; len--, bitmap++) {
weight = hweight8(*bitmap);
bitflips += BITS_PER_BYTE - weight;
if (unlikely(bitflips > bitflips_threshold))
return -EBADMSG;
}
return bitflips;
}
/**
* nand_check_erased_ecc_chunk - check if an ECC chunk contains (almost) only
* 0xff data
* @data: data buffer to test
* @datalen: data length
* @ecc: ECC buffer
* @ecclen: ECC length
* @extraoob: extra OOB buffer
* @extraooblen: extra OOB length
* @bitflips_threshold: maximum number of bitflips
*
* Check if a data buffer and its associated ECC and OOB data contains only
* 0xff pattern, which means the underlying region has been erased and is
* ready to be programmed.
* The bitflips_threshold specify the maximum number of bitflips before
* considering the region as not erased.
*
* Note:
* 1/ ECC algorithms are working on pre-defined block sizes which are usually
* different from the NAND page size. When fixing bitflips, ECC engines will
* report the number of errors per chunk, and the NAND core infrastructure
* expect you to return the maximum number of bitflips for the whole page.
* This is why you should always use this function on a single chunk and
* not on the whole page. After checking each chunk you should update your
* max_bitflips value accordingly.
* 2/ When checking for bitflips in erased pages you should not only check
* the payload data but also their associated ECC data, because a user might
* have programmed almost all bits to 1 but a few. In this case, we
* shouldn't consider the chunk as erased, and checking ECC bytes prevent
* this case.
* 3/ The extraoob argument is optional, and should be used if some of your OOB
* data are protected by the ECC engine.
* It could also be used if you support subpages and want to attach some
* extra OOB data to an ECC chunk.
*
* Returns a positive number of bitflips less than or equal to
* bitflips_threshold, or -ERROR_CODE for bitflips in excess of the
* threshold. In case of success, the passed buffers are filled with 0xff.
*/
int nand_check_erased_ecc_chunk(void *data, int datalen,
void *ecc, int ecclen,
void *extraoob, int extraooblen,
int bitflips_threshold)
{
int data_bitflips = 0, ecc_bitflips = 0, extraoob_bitflips = 0;
data_bitflips = nand_check_erased_buf(data, datalen,
bitflips_threshold);
if (data_bitflips < 0)
return data_bitflips;
bitflips_threshold -= data_bitflips;
ecc_bitflips = nand_check_erased_buf(ecc, ecclen, bitflips_threshold);
if (ecc_bitflips < 0)
return ecc_bitflips;
bitflips_threshold -= ecc_bitflips;
extraoob_bitflips = nand_check_erased_buf(extraoob, extraooblen,
bitflips_threshold);
if (extraoob_bitflips < 0)
return extraoob_bitflips;
if (data_bitflips)
memset(data, 0xff, datalen);
if (ecc_bitflips)
memset(ecc, 0xff, ecclen);
if (extraoob_bitflips)
memset(extraoob, 0xff, extraooblen);
return data_bitflips + ecc_bitflips + extraoob_bitflips;
}
EXPORT_SYMBOL(nand_check_erased_ecc_chunk);
/**
* nanddev_isbad() - Check if a block is bad
* @nand: NAND device

131
drivers/mtd/nand/raw/nand_base.c
View File

@ -2783,137 +2783,6 @@ int nand_set_features(struct nand_chip *chip, int addr,
return nand_set_features_op(chip, addr, subfeature_param);
}
/**
* nand_check_erased_buf - check if a buffer contains (almost) only 0xff data
* @buf: buffer to test
* @len: buffer length
* @bitflips_threshold: maximum number of bitflips
*
* Check if a buffer contains only 0xff, which means the underlying region
* has been erased and is ready to be programmed.
* The bitflips_threshold specify the maximum number of bitflips before
* considering the region is not erased.
* Note: The logic of this function has been extracted from the memweight
* implementation, except that nand_check_erased_buf function exit before
* testing the whole buffer if the number of bitflips exceed the
* bitflips_threshold value.
*
* Returns a positive number of bitflips less than or equal to
* bitflips_threshold, or -ERROR_CODE for bitflips in excess of the
* threshold.
*/
static int nand_check_erased_buf(void *buf, int len, int bitflips_threshold)
{
const unsigned char *bitmap = buf;
int bitflips = 0;
int weight;
for (; len && ((uintptr_t)bitmap) % sizeof(long);
len--, bitmap++) {
weight = hweight8(*bitmap);
bitflips += BITS_PER_BYTE - weight;
if (unlikely(bitflips > bitflips_threshold))
return -EBADMSG;
}
for (; len >= sizeof(long);
len -= sizeof(long), bitmap += sizeof(long)) {
unsigned long d = *((unsigned long *)bitmap);
if (d == ~0UL)
continue;
weight = hweight_long(d);
bitflips += BITS_PER_LONG - weight;
if (unlikely(bitflips > bitflips_threshold))
return -EBADMSG;
}
for (; len > 0; len--, bitmap++) {
weight = hweight8(*bitmap);
bitflips += BITS_PER_BYTE - weight;
if (unlikely(bitflips > bitflips_threshold))
return -EBADMSG;
}
return bitflips;
}
/**
* nand_check_erased_ecc_chunk - check if an ECC chunk contains (almost) only
* 0xff data
* @data: data buffer to test
* @datalen: data length
* @ecc: ECC buffer
* @ecclen: ECC length
* @extraoob: extra OOB buffer
* @extraooblen: extra OOB length
* @bitflips_threshold: maximum number of bitflips
*
* Check if a data buffer and its associated ECC and OOB data contains only
* 0xff pattern, which means the underlying region has been erased and is
* ready to be programmed.
* The bitflips_threshold specify the maximum number of bitflips before
* considering the region as not erased.
*
* Note:
* 1/ ECC algorithms are working on pre-defined block sizes which are usually
* different from the NAND page size. When fixing bitflips, ECC engines will
* report the number of errors per chunk, and the NAND core infrastructure
* expect you to return the maximum number of bitflips for the whole page.
* This is why you should always use this function on a single chunk and
* not on the whole page. After checking each chunk you should update your
* max_bitflips value accordingly.
* 2/ When checking for bitflips in erased pages you should not only check
* the payload data but also their associated ECC data, because a user might
* have programmed almost all bits to 1 but a few. In this case, we
* shouldn't consider the chunk as erased, and checking ECC bytes prevent
* this case.
* 3/ The extraoob argument is optional, and should be used if some of your OOB
* data are protected by the ECC engine.
* It could also be used if you support subpages and want to attach some
* extra OOB data to an ECC chunk.
*
* Returns a positive number of bitflips less than or equal to
* bitflips_threshold, or -ERROR_CODE for bitflips in excess of the
* threshold. In case of success, the passed buffers are filled with 0xff.
*/
int nand_check_erased_ecc_chunk(void *data, int datalen,
void *ecc, int ecclen,
void *extraoob, int extraooblen,
int bitflips_threshold)
{
int data_bitflips = 0, ecc_bitflips = 0, extraoob_bitflips = 0;
data_bitflips = nand_check_erased_buf(data, datalen,
bitflips_threshold);
if (data_bitflips < 0)
return data_bitflips;
bitflips_threshold -= data_bitflips;
ecc_bitflips = nand_check_erased_buf(ecc, ecclen, bitflips_threshold);
if (ecc_bitflips < 0)
return ecc_bitflips;
bitflips_threshold -= ecc_bitflips;
extraoob_bitflips = nand_check_erased_buf(extraoob, extraooblen,
bitflips_threshold);
if (extraoob_bitflips < 0)
return extraoob_bitflips;
if (data_bitflips)
memset(data, 0xff, datalen);
if (ecc_bitflips)
memset(ecc, 0xff, ecclen);
if (extraoob_bitflips)
memset(extraoob, 0xff, extraooblen);
return data_bitflips + ecc_bitflips + extraoob_bitflips;
}
EXPORT_SYMBOL(nand_check_erased_ecc_chunk);
/**
* nand_read_page_raw_notsupp - dummy read raw page function
* @chip: nand chip info structure

5
include/linux/mtd/nand.h
View File

@ -1136,4 +1136,9 @@ static inline bool nanddev_bbt_is_initialized(struct nand_device *nand)
int nanddev_mtd_erase(struct mtd_info *mtd, struct erase_info *einfo);
int nanddev_mtd_max_bad_blocks(struct mtd_info *mtd, loff_t offs, size_t len);
int nand_check_erased_ecc_chunk(void *data, int datalen,
void *ecc, int ecclen,
void *extraoob, int extraooblen,
int threshold);
#endif /* __LINUX_MTD_NAND_H */

5
include/linux/mtd/rawnand.h
View File

@ -1519,11 +1519,6 @@ int rawnand_sw_bch_correct(struct nand_chip *chip, unsigned char *buf,
unsigned char *read_ecc, unsigned char *calc_ecc);
void rawnand_sw_bch_cleanup(struct nand_chip *chip);
int nand_check_erased_ecc_chunk(void *data, int datalen,
void *ecc, int ecclen,
void *extraoob, int extraooblen,
int threshold);
int nand_ecc_choose_conf(struct nand_chip *chip,
const struct nand_ecc_caps *caps, int oobavail);