On Wed, Dec 14, 2016 at 08:59:08AM +0100, Jan Remmet wrote:
> imx6ul secure the fcb with bch 40. The imx-kobs tool use a own modified
> bch lib. They reverse the bit order of the data and the ecc.
> To use the bch lib in barebox the bytes in the data buffers must be
> reversed.
> The data layout on nand is bit aligned. But with 40 bits this is not an
> issue for imx6ul now.
I saw that this wasn't applied, is there any rework needed?
Jan
>
> Signed-off-by: Jan Remmet <j.remmet@xxxxxxxxx>
> ---
> common/Kconfig | 1 +
> common/imx-bbu-nand-fcb.c | 145 +++++++++++++++++++++++++++++++++++++++++++++-
> 2 files changed, 143 insertions(+), 3 deletions(-)
>
> diff --git a/common/Kconfig b/common/Kconfig
> index ed472a0..a10caf6 100644
> --- a/common/Kconfig
> +++ b/common/Kconfig
> @@ -101,6 +101,7 @@ config BAREBOX_UPDATE_IMX_NAND_FCB
> depends on BAREBOX_UPDATE
> depends on MTD_WRITE
> depends on NAND_MXS
> + select BCH if ARCH_IMX6
> default y
>
> config UBIFORMAT
> diff --git a/common/imx-bbu-nand-fcb.c b/common/imx-bbu-nand-fcb.c
> index 34a5f83..5d3d3f7 100644
> --- a/common/imx-bbu-nand-fcb.c
> +++ b/common/imx-bbu-nand-fcb.c
> @@ -33,9 +33,12 @@
> #include <linux/mtd/mtd.h>
> #include <linux/mtd/nand.h>
> #include <linux/stat.h>
> +#include <linux/bch.h>
> +#include <linux/bitops.h>
> #include <io.h>
> #include <crc.h>
> #include <mach/generic.h>
> +#include <mach/imx6.h>
> #include <mtd/mtd-peb.h>
>
> struct dbbt_block {
> @@ -129,6 +132,132 @@ static uint8_t calculate_parity_13_8(uint8_t d)
> return p;
> }
>
> +static uint8_t reverse_bit(uint8_t b)
> +{
> + b = (b & 0xf0) >> 4 | (b & 0x0f) << 4;
> + b = (b & 0xcc) >> 2 | (b & 0x33) << 2;
> + b = (b & 0xaa) >> 1 | (b & 0x55) << 1;
> +
> + return b;
> +}
> +
> +static void encode_bch_ecc(void *buf, struct fcb_block *fcb, int eccbits)
> +{
> + int i, j, m = 13;
> + int blocksize = 128;
> + int numblocks = 8;
> + int ecc_buf_size = (m * eccbits + 7) / 8;
> + struct bch_control *bch = init_bch(m, eccbits, 0);
> + uint8_t *ecc_buf = xmalloc(ecc_buf_size);
> + uint8_t *tmp_buf = xzalloc(blocksize * numblocks);
> + uint8_t *psrc, *pdst;
> +
> + /*
> + * The blocks here are bit aligned. If eccbits is a multiple of 8,
> + * we just can copy bytes. Otherwiese we must move the blocks to
> + * the next free bit position.
> + */
> + BUG_ON(eccbits % 8);
> +
> + memcpy(tmp_buf, fcb, sizeof(*fcb));
> +
> + for (i = 0; i < numblocks; i++) {
> + memset(ecc_buf, 0, ecc_buf_size);
> + psrc = tmp_buf + i * blocksize;
> + pdst = buf + i * (blocksize + ecc_buf_size);
> +
> + /* copy data byte aligned to destination buf */
> + memcpy(pdst, psrc, blocksize);
> +
> + /*
> + * imx-kobs use a modified encode_bch which reverse the
> + * bit order of the data before calculating bch.
> + * Do this in the buffer and use the bch lib here.
> + */
> + for (j = 0; j < blocksize; j++)
> + psrc[j] = reverse_bit(psrc[j]);
> +
> + encode_bch(bch, psrc, blocksize, ecc_buf);
> +
> + /* reverse ecc bit */
> + for (j = 0; j < ecc_buf_size; j++)
> + ecc_buf[j] = reverse_bit(ecc_buf[j]);
> +
> + /* Here eccbuf is byte aligned and we can just copy it */
> + memcpy(pdst + blocksize, ecc_buf, ecc_buf_size);
> + }
> +
> + free(ecc_buf);
> + free(tmp_buf);
> + free_bch(bch);
> +}
> +
> +struct fcb_block *read_fcb_bch(void *rawpage, int eccbits)
> +{
> + int i, j, ret, errbit, m = 13;
> + int blocksize = 128;
> + int numblocks = 8;
> + int ecc_buf_size = (m * eccbits + 7) / 8;
> + struct bch_control *bch = init_bch(m, eccbits, 0);
> + uint8_t *fcb = xmalloc(numblocks * blocksize);
> + uint8_t *ecc_buf = xmalloc(ecc_buf_size);
> + uint8_t *data_buf = xmalloc(blocksize);
> + unsigned int *errloc = xmalloc(eccbits * sizeof(*errloc));
> + uint8_t *psrc, *pdst;
> +
> + /* see encode_bch_ecc */
> + BUG_ON(eccbits % 8);
> +
> + for (i = 0; i < numblocks; i++) {
> + psrc = rawpage + 32 + i * (blocksize + ecc_buf_size);
> + pdst = fcb + i * blocksize;
> +
> + /* reverse data bit */
> + for (j = 0; j < blocksize; j++)
> + data_buf[j] = reverse_bit(psrc[j]);
> +
> + /* reverse ecc bit */
> + for (j = 0; j < ecc_buf_size; j++)
> + ecc_buf[j] = reverse_bit(psrc[j + blocksize]);
> +
> + ret = decode_bch(bch, data_buf, blocksize, ecc_buf,
> + NULL, NULL, errloc);
> +
> + if (ret < 0) {
> + pr_err("Uncorrectable error at block %d\n", i);
> + free(fcb);
> + fcb = ERR_PTR(ret);
> + goto out;
> + }
> + if (ret > 0)
> + pr_info("Found %d correctable errors in block %d\n",
> + ret, i);
> +
> + for (j = 0; j < ret; j++) {
> + /*
> + * calculate the reverse position
> + * pos - (pos % 8) -> byte offset
> + * 7 - (pos % 8) -> reverse bit position
> + */
> + errbit = errloc[j] - 2 * (errloc[j] % 8) + 7;
> + pr_debug("Found error: bit %d in block %d\n",
> + errbit, i);
> + if (errbit < blocksize * 8)
> + change_bit(errbit, psrc);
> + /* else error in ecc, ignore it */
> + }
> + memcpy(pdst, psrc, blocksize);
> + }
> +
> +out:
> + free(data_buf);
> + free(ecc_buf);
> + free(errloc);
> + free_bch(bch);
> +
> + return (struct fcb_block *)fcb;
> +}
> +
> static void encode_hamming_13_8(void *_src, void *_ecc, size_t size)
> {
> int i;
> @@ -312,7 +441,11 @@ static int read_fcb(struct mtd_info *mtd, int num, struct fcb_block **retfcb)
> goto err;
> }
>
> - fcb = read_fcb_hamming_13_8(rawpage);
> + if (cpu_is_mx6ul())
> + fcb = read_fcb_bch(rawpage, 40);
> + else
> + fcb = read_fcb_hamming_13_8(rawpage);
> +
> if (IS_ERR(fcb)) {
> pr_err("Cannot read fcb\n");
> ret = PTR_ERR(fcb);
> @@ -766,8 +899,14 @@ static int imx_bbu_write_fcbs_dbbts(struct mtd_info *mtd, struct fcb_block *fcb)
>
> fcb_raw_page = xzalloc(mtd->writesize + mtd->oobsize);
>
> - memcpy(fcb_raw_page + 12, fcb, sizeof(struct fcb_block));
> - encode_hamming_13_8(fcb_raw_page + 12, fcb_raw_page + 12 + 512, 512);
> + if (cpu_is_mx6ul()) {
> + /* 40 bit BCH, for i.MX6UL */
> + encode_bch_ecc(fcb_raw_page + 32, fcb, 40);
> + } else {
> + memcpy(fcb_raw_page + 12, fcb, sizeof(struct fcb_block));
> + encode_hamming_13_8(fcb_raw_page + 12,
> + fcb_raw_page + 12 + 512, 512);
> + }
>
> dbbt = dbbt_data_create(mtd);
>
> --
> 2.7.4
>
>
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