On Tue, 8 May 2018 14:19:54 -0700
Jane Wan <jane....@nokia.com> wrote:
> 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....@nokia.com>
> ---
> drivers/mtd/nand/raw/nand_base.c | 49
> ++++++++++++++++++++++++++++++++++----
> 1 file changed, 44 insertions(+), 5 deletions(-)
>
> diff --git a/drivers/mtd/nand/raw/nand_base.c
> b/drivers/mtd/nand/raw/nand_base.c
> index 72f3a89..dfc341c 100644
> --- a/drivers/mtd/nand/raw/nand_base.c
> +++ b/drivers/mtd/nand/raw/nand_base.c
> @@ -5086,6 +5086,38 @@ static int nand_flash_detect_ext_param_page(struct
> nand_chip *chip,
> return ret;
> }
>
> +#define GET_BIT(bit, val) (((val) >> (bit)) & 0x01)
> +
> +/*
> + * Recover NAND parameter page with bit-wise majority
> + */
> +static int onfi_recover_param(struct nand_onfi_params *p, int pages)
I had something more generic in mind:
static void nand_bit_wise_majority(const void **srcbufs,
void *dstbuf,
unsigned int nbufs,
unsigned int bufsize)
{
...
}
And then you do the crc check in nand_flash_detect_onfi().
The reason I'm asking that is because I'm almost sure we'll re-use this
functions for extended param pages, and also for vendor specific data
(we already have a byte-wise majority check in the hynix driver, so I
wouldn't be surprised if other vendors decided to use a bit-wise
approach for some of their OTP area).
> +{
> + int i, j, k;
> + u8 v, m;
> + u8 *buf;
> +
> + buf = (u8 *)p;
> + for (i = 0; i < sizeof(*p); i++) {
> + v = 0;
> + for (j = 0; j < 8; j++) {
> + m = 0;
> + for (k = 0; k < pages; k++)
> + m += GET_BIT(j, buf[k*sizeof(*p) + i]);
> + if (m > pages/2)
> + v |= BIT(j);
> + }
> + ((u8 *)p)[i] = v;
> + }
> +
> + if (onfi_crc16(ONFI_CRC_BASE, (u8 *)p, 254) ==
> + le16_to_cpu(p->crc)) {
> + return 1;
> + }
> +
> + return 0;
> +}
> +
> /*
> * Check if the NAND chip is ONFI compliant, returns 1 if it is, 0 otherwise.
> */
> @@ -5102,7 +5134,7 @@ 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 +5145,28 @@ 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");
> + ret = onfi_recover_param(p, 3);
> + if (ret == 0) {
> + pr_err("ONFI parameter recovery failed, aborting\n");
> + goto free_onfi_param_page;
> + }
> }
>
> /* Check version */
