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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 <Jane.Wan@nokia.com>
Signed-off-by: Boris Brezillon <boris.brezillon@bootlin.com>
This commit is contained in:
Wan, Jane (Nokia - US/Sunnyvale) 2018-05-13 04:30:02 +00:00 committed by Boris Brezillon
parent a676688032
commit 39138c1f4a
1 changed files with 47 additions and 5 deletions
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52
drivers/mtd/nand/raw/nand_base.c
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@ -5086,6 +5086,37 @@ static int nand_flash_detect_ext_param_page(struct nand_chip *chip,
return ret; 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. * 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; return 0;
/* ONFI chip: allocate a buffer to hold its parameter page */ /* 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) if (!p)
return -ENOMEM; return -ENOMEM;
@ -5113,21 +5144,32 @@ static int nand_flash_detect_onfi(struct nand_chip *chip)
} }
for (i = 0; i < 3; i++) { 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) { if (ret) {
ret = 0; ret = 0;
goto free_onfi_param_page; 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)) { le16_to_cpu(p->crc)) {
if (i)
memcpy(p, &p[i], sizeof(*p));
break; break;
} }
} }
if (i == 3) { if (i == 3) {
pr_err("Could not find valid ONFI parameter page; aborting\n"); const void *srcbufs[3] = {p, p + 1, p + 2};
goto free_onfi_param_page;
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 */ /* Check version */