From 39138c1f4a31f3468fa2e44aba4495c0c30da205 Mon Sep 17 00:00:00 2001 From: "Wan, Jane (Nokia - US/Sunnyvale)" Date: Sun, 13 May 2018 04:30:02 +0000 Subject: [PATCH] mtd: rawnand: use bit-wise majority to recover the ONFI param page 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 page from the parameter page copies present. Signed-off-by: Jane Wan Signed-off-by: Boris Brezillon --- drivers/mtd/nand/raw/nand_base.c | 52 +++++++++++++++++++++++++++++--- 1 file changed, 47 insertions(+), 5 deletions(-) diff --git a/drivers/mtd/nand/raw/nand_base.c b/drivers/mtd/nand/raw/nand_base.c index 414a2a3a91d0..faf10c890a3d 100644 --- a/drivers/mtd/nand/raw/nand_base.c +++ b/drivers/mtd/nand/raw/nand_base.c @@ -5086,6 +5086,37 @@ ext_out: return ret; } +/* + * Recover data with bit-wise majority + */ +static void nand_bit_wise_majority(const void **srcbufs, + unsigned int nsrcbufs, + void *dstbuf, + unsigned int bufsize) +{ + int i, j, k; + + for (i = 0; i < bufsize; i++) { + u8 val = 0; + + for (j = 0; j < 8; j++) { + unsigned int cnt = 0; + + for (k = 0; k < nsrcbufs; k++) { + const u8 *srcbuf = srcbufs[k]; + + if (srcbuf[i] & BIT(j)) + cnt++; + } + + if (cnt > nsrcbufs / 2) + val |= BIT(j); + } + + ((u8 *)dstbuf)[i] = val; + } +} + /* * Check if the NAND chip is ONFI compliant, returns 1 if it is, 0 otherwise. */ @@ -5102,7 +5133,7 @@ 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 +5144,32 @@ 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; + const void *srcbufs[3] = {p, p + 1, p + 2}; + + pr_warn("Could not find a valid ONFI parameter page, trying bit-wise majority to recover it\n"); + nand_bit_wise_majority(srcbufs, ARRAY_SIZE(srcbufs), p, + 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 */