diff options
Diffstat (limited to 'drivers/mtd/nand/core.c')
| -rw-r--r-- | drivers/mtd/nand/core.c | 146 |
1 files changed, 140 insertions, 6 deletions
diff --git a/drivers/mtd/nand/core.c b/drivers/mtd/nand/core.c index 416947f28b67..3e76d127715f 100644 --- a/drivers/mtd/nand/core.c +++ b/drivers/mtd/nand/core.c @@ -13,6 +13,137 @@ #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 * @pos: position pointing to the block we want to check @@ -21,7 +152,7 @@ */ bool nanddev_isbad(struct nand_device *nand, const struct nand_pos *pos) { - if (WARN_ONCE(mtd_expert_analysis_mode, mtd_expert_analysis_warning)) + if (mtd_check_expert_analysis_mode()) return false; if (nanddev_bbt_is_initialized(nand)) { @@ -126,7 +257,7 @@ EXPORT_SYMBOL_GPL(nanddev_isreserved); * * Return: 0 in case of success, a negative error code otherwise. */ -int nanddev_erase(struct nand_device *nand, const struct nand_pos *pos) +static int nanddev_erase(struct nand_device *nand, const struct nand_pos *pos) { if (nanddev_isbad(nand, pos) || nanddev_isreserved(nand, pos)) { pr_warn("attempt to erase a bad/reserved block @%llx\n", @@ -136,7 +267,6 @@ int nanddev_erase(struct nand_device *nand, const struct nand_pos *pos) return nand->ops->erase(nand, pos); } -EXPORT_SYMBOL_GPL(nanddev_erase); /** * nanddev_mtd_erase() - Generic mtd->_erase() implementation for NAND devices @@ -235,7 +365,9 @@ static int nanddev_get_ecc_engine(struct nand_device *nand) nand->ecc.engine = nand_ecc_get_on_die_hw_engine(nand); break; case NAND_ECC_ENGINE_TYPE_ON_HOST: - pr_err("On-host hardware ECC engines not supported yet\n"); + nand->ecc.engine = nand_ecc_get_on_host_hw_engine(nand); + if (PTR_ERR(nand->ecc.engine) == -EPROBE_DEFER) + return -EPROBE_DEFER; break; default: pr_err("Missing ECC engine type\n"); @@ -255,7 +387,7 @@ static int nanddev_put_ecc_engine(struct nand_device *nand) { switch (nand->ecc.ctx.conf.engine_type) { case NAND_ECC_ENGINE_TYPE_ON_HOST: - pr_err("On-host hardware ECC engines not supported yet\n"); + nand_ecc_put_on_host_hw_engine(nand); break; case NAND_ECC_ENGINE_TYPE_NONE: case NAND_ECC_ENGINE_TYPE_SOFT: @@ -300,7 +432,9 @@ int nanddev_ecc_engine_init(struct nand_device *nand) /* Look for the ECC engine to use */ ret = nanddev_get_ecc_engine(nand); if (ret) { - pr_err("No ECC engine found\n"); + if (ret != -EPROBE_DEFER) + pr_err("No ECC engine found\n"); + return ret; } |