Messages in this thread Patch in this message | | | From | Jane Wan <> | Subject | [PATCH v5 2/2] mtd: rawnand: use bit-wise majority to recover the contents of ONFI parameter | Date | Wed, 9 May 2018 19:46:40 -0700 |
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Per ONFI specification (Rev. 4.0), if all parameter pages have invalid CRC values, the bit-wise majority may be used to recover the contents of the parameter pages from the parameter page copies present.
Signed-off-by: Jane Wan <Jane.Wan@nokia.com> --- drivers/mtd/nand/raw/nand_base.c | 46 +++++++++++++++++++++++++++++++++----- 1 file changed, 41 insertions(+), 5 deletions(-)
diff --git a/drivers/mtd/nand/raw/nand_base.c b/drivers/mtd/nand/raw/nand_base.c index 72f3a89..a7c2507 100644 --- a/drivers/mtd/nand/raw/nand_base.c +++ b/drivers/mtd/nand/raw/nand_base.c @@ -5086,6 +5086,34 @@ static int nand_flash_detect_ext_param_page(struct nand_chip *chip, return ret; } +#define GET_BIT(bit, val) (((val) >> (bit)) & 0x01) + +/* + * Recover data with bit-wise majority + */ +static void nand_bit_wise_majority(const void **srcbufs, + void *dstbuf, + unsigned int nbufs, + unsigned int bufsize) +{ + int i, j, k; + u8 v, m; + u8 *p; + + p = *(u8 **)srcbufs; + for (i = 0; i < bufsize; i++) { + v = 0; + for (j = 0; j < 8; j++) { + m = 0; + for (k = 0; k < nbufs; k++) + m += GET_BIT(j, p[k*bufsize + i]); + if (m > nbufs/2) + v |= BIT(j); + } + ((u8 *)dstbuf)[i] = v; + } +} + /* * Check if the NAND chip is ONFI compliant, returns 1 if it is, 0 otherwise. */ @@ -5102,7 +5130,7 @@ static int nand_flash_detect_onfi(struct nand_chip *chip) return 0; /* ONFI chip: allocate a buffer to hold its parameter page */ - p = kzalloc(sizeof(*p), GFP_KERNEL); + p = kzalloc((sizeof(*p) * 3), GFP_KERNEL); if (!p) return -ENOMEM; @@ -5113,21 +5141,29 @@ static int nand_flash_detect_onfi(struct nand_chip *chip) } for (i = 0; i < 3; i++) { - ret = nand_read_data_op(chip, p, sizeof(*p), true); + ret = nand_read_data_op(chip, &p[i], sizeof(*p), true); if (ret) { ret = 0; goto free_onfi_param_page; } - if (onfi_crc16(ONFI_CRC_BASE, (uint8_t *)p, 254) == + if (onfi_crc16(ONFI_CRC_BASE, (u8 *)&p[i], 254) == le16_to_cpu(p->crc)) { + if (i) + memcpy(p, &p[i], sizeof(*p)); break; } } if (i == 3) { - pr_err("Could not find valid ONFI parameter page; aborting\n"); - goto free_onfi_param_page; + pr_err("Could not find valid ONFI parameter page\n"); + pr_info("Recover ONFI params with bit-wise majority\n"); + nand_bit_wise_majority((const void **)&p, p, 3, sizeof(*p)); + if (onfi_crc16(ONFI_CRC_BASE, (u8 *)p, 254) != + le16_to_cpu(p->crc)) { + pr_err("ONFI parameter recovery failed, aborting\n"); + goto free_onfi_param_page; + } } /* Check version */ -- 1.7.9.5
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