diff options
Diffstat (limited to 'drivers/mtd/nand/raw/nand_base.c')
-rw-r--r-- | drivers/mtd/nand/raw/nand_base.c | 131 |
1 files changed, 0 insertions, 131 deletions
diff --git a/drivers/mtd/nand/raw/nand_base.c b/drivers/mtd/nand/raw/nand_base.c index 13e4060bd1b6..c7d9501f646b 100644 --- a/drivers/mtd/nand/raw/nand_base.c +++ b/drivers/mtd/nand/raw/nand_base.c @@ -2784,137 +2784,6 @@ int nand_set_features(struct nand_chip *chip, int addr, } /** - * 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 * @buf: buffer to store read data |