On Thu, 30 Jul 2015 19:34:53 +0200 Boris Brezillon <[email protected]> wrote:
> Add two helper functions to help NAND controller drivers test whether a > specific NAND region is erased or not. > > Signed-off-by: Boris Brezillon <[email protected]> > --- > drivers/mtd/nand/nand_base.c | 104 > +++++++++++++++++++++++++++++++++++++++++++ > include/linux/mtd/nand.h | 8 ++++ > 2 files changed, 112 insertions(+) > > diff --git a/drivers/mtd/nand/nand_base.c b/drivers/mtd/nand/nand_base.c > index ceb68ca..1542ea7 100644 > --- a/drivers/mtd/nand/nand_base.c > +++ b/drivers/mtd/nand/nand_base.c > @@ -1101,6 +1101,110 @@ out: > EXPORT_SYMBOL(nand_lock); > > /** > + * 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 or -ERROR_CODE. > + */ > +int nand_check_erased_buf(void *buf, int len, int bitflips_threshold) > +{ > + const unsigned char *bitmap = buf; > + int bitflips = 0; > + int weight; > + int longs; > + > + for (; len && ((unsigned long)bitmap) % sizeof(long); > + len--, bitmap++) { > + weight = hweight8(*bitmap); > + > + bitflips += sizeof(u8) - weight; > + if (bitflips > bitflips_threshold) > + return -EINVAL; > + } > + > + > + for (longs = len / sizeof(long); longs; > + longs--, bitmap += sizeof(long)) { > + BUG_ON(longs >= INT_MAX / BITS_PER_LONG); > + weight = hweight_long(*((unsigned long *)bitmap)); > + > + bitflips += sizeof(long) - weight; > + if (bitflips > bitflips_threshold) > + return -EINVAL; > + } > + > + len %= sizeof(long); > + > + for (; len > 0; len--, bitmap++) { > + weight = hweight8(*bitmap); > + bitflips += sizeof(u8) - weight; > + } > + > + return bitflips; > +} > +EXPORT_SYMBOL(nand_check_erased_buf); > + > +/** > + * 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. > + * > + * Returns a positive number of bitflips or -ERROR_CODE. > + */ > +int nand_check_erased_ecc_chunk(void *data, int datalen, > + void *ecc, int ecclen, > + void *extraoob, int extraooblen, > + int bitflips_threshold) > +{ > + int bitflips = 0; > + int ret; > + > + ret = nand_check_erased_buf(data, datalen, bitflips_threshold); > + if (ret < 0) > + return ret; > + > + bitflips += ret; > + bitflips_threshold -= ret; > + > + ret = nand_check_erased_buf(ecc, ecclen, bitflips_threshold); > + if (ret < 0) > + return ret; > + > + bitflips += ret; > + bitflips_threshold -= ret; > + > + ret = nand_check_erased_buf(extraoob, extraooblen, bitflips_threshold); > + if (ret < 0) > + return ret; > + Forgot the memset operations here: memset(data, 0xff, datalen); memset(ecc, 0xff, ecclen); memset(extraoob, 0xff, extraooblen); > + return bitflips + ret; > +} > +EXPORT_SYMBOL(nand_check_erased_ecc_chunk); > + > +/** > * nand_read_page_raw - [INTERN] read raw page data without ecc > * @mtd: mtd info structure > * @chip: nand chip info structure > diff --git a/include/linux/mtd/nand.h b/include/linux/mtd/nand.h > index 272f429..ae06a07 100644 > --- a/include/linux/mtd/nand.h > +++ b/include/linux/mtd/nand.h > @@ -1030,4 +1030,12 @@ struct nand_sdr_timings { > > /* get timing characteristics from ONFI timing mode. */ > const struct nand_sdr_timings *onfi_async_timing_mode_to_sdr_timings(int > mode); > + > +int nand_check_erased_buf(void *data, int datalen, > + int threshold); > + > +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 */ -- Boris Brezillon, Free Electrons Embedded Linux and Kernel engineering http://free-electrons.com -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to [email protected] More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
