[PATCH] cmd: nand biterr - Add support for nand biterr command

[Balamanikandan.Gunasundar at microchip.com]

Hello,

Can you please provide your comments on this patch.

Thanks,
Balamanikandan

On 29/06/21 12:46 pm, Balamanikandan Gunasundar wrote:
> The command shall be used to induce bit errors in the nand page
> manually. The code flips a bit in the specified offset without
> changing the ECC. This helps to see how the software handles the
> error.
> 
> The patch is ported from
> https://patchwork.ozlabs.org/project/uboot/patch/\
> 1325691123-19565-1-git-send-email-holger.brunck at keymile.com
> 
> The implementation is inspired from
> 'mtd-utils/nand-utils/nandflipbits.c'
> 
> Signed-off-by: Balamanikandan Gunasundar <balamanikandan.gunasundar at microchip.com>
> ---
>   cmd/nand.c | 127 +++++++++++++++++++++++++++++++++++++++++++++++++++--
>   1 file changed, 124 insertions(+), 3 deletions(-)
> 
> diff --git a/cmd/nand.c b/cmd/nand.c
> index 5bda69e819..ea1b0f9434 100644
> --- a/cmd/nand.c
> +++ b/cmd/nand.c
> @@ -17,6 +17,10 @@
>    * and/or modified under the terms of the GNU General Public License as
>    * published by the Free Software Foundation; either version 2 of the
>    * License, or (at your option) any later version.
> + *
> + * The function nand_biterror() in this file is inspired from
> + * mtd-utils/nand-utils/nandflipbits.c which was released under GPLv2
> + * only
>    */
>   
>   #include <common.h>
> @@ -40,6 +44,116 @@ int find_dev_and_part(const char *id, struct mtd_device **dev,
>   		      u8 *part_num, struct part_info **part);
>   #endif
>   
> +#define MAX_NUM_PAGES 64
> +
> +static int nand_biterror(struct mtd_info *mtd, ulong off, int bit)
> +{
> +	int ret = 0;
> +	int page = 0;
> +	ulong  block_off;
> +	u_char *datbuf[MAX_NUM_PAGES]; /* Data and OOB */
> +	u_char data;
> +	int pages_per_blk = mtd->erasesize / mtd->writesize;
> +	struct erase_info einfo;
> +
> +	if (pages_per_blk > MAX_NUM_PAGES) {
> +		printf("Too many pages in one erase block\n");
> +		return 1;
> +	}
> +
> +	if (bit < 0 || bit > 7) {
> +		printf("bit position 0 to 7 is allowed\n");
> +		return 1;
> +	}
> +
> +	/* Allocate memory */
> +	memset(datbuf, 0, sizeof(datbuf));
> +	for (page = 0; page < pages_per_blk ; page++) {
> +		datbuf[page] = malloc(mtd->writesize + mtd->oobsize);
> +		if (!datbuf[page]) {
> +			printf("No memory for page buffer\n");
> +			ret = -ENOMEM;
> +			goto free_memory;
> +		}
> +	}
> +
> +	/* Align to erase block boundary */
> +	block_off = off & (~(mtd->erasesize - 1));
> +
> +	/* Read out memory as first step */
> +	for (page = 0; page < pages_per_blk ; page++) {
> +		struct mtd_oob_ops ops;
> +		loff_t addr = (loff_t)block_off;
> +
> +		memset(&ops, 0, sizeof(ops));
> +		ops.datbuf = datbuf[page];
> +		ops.oobbuf = datbuf[page] + mtd->writesize;
> +		ops.len = mtd->writesize;
> +		ops.ooblen = mtd->oobsize;
> +		ops.mode = MTD_OPS_RAW;
> +		ret = mtd_read_oob(mtd, addr, &ops);
> +		if (ret < 0) {
> +			printf("Error (%d) reading page %08lx\n",
> +			       ret, block_off);
> +			ret = 1;
> +			goto free_memory;
> +		}
> +		block_off += mtd->writesize;
> +	}
> +
> +	/* Erase the block */
> +	memset(&einfo, 0, sizeof(einfo));
> +	einfo.mtd = mtd;
> +	/* Align to erase block boundary */
> +	einfo.addr = (loff_t)(off & (~(mtd->erasesize - 1)));
> +	einfo.len = mtd->erasesize;
> +	ret = mtd_erase(mtd, &einfo);
> +	if (ret < 0) {
> +		printf("Error (%d) nand_erase_nand page %08llx\n",
> +		       ret, einfo.addr);
> +		ret = 1;
> +		goto free_memory;
> +	}
> +
> +	/* Twist a bit in data part */
> +	block_off = off & (mtd->erasesize - 1);
> +	data = datbuf[block_off / mtd->writesize][block_off % mtd->writesize];
> +	data ^= (1 << bit);
> +	datbuf[block_off / mtd->writesize][block_off % mtd->writesize] = data;
> +
> +	printf("Flip data at 0x%lx with xor 0x%02x (bit=%d) to value=0x%02x\n",
> +	       off, (1 << bit), bit, data);
> +
> +	/* Write back twisted data and unmodified OOB */
> +	/* Align to erase block boundary */
> +	block_off = off & (~(mtd->erasesize - 1));
> +	for (page = 0; page < pages_per_blk; page++) {
> +		struct mtd_oob_ops ops;
> +		loff_t addr = (loff_t)block_off;
> +
> +		memset(&ops, 0, sizeof(ops));
> +		ops.datbuf = datbuf[page];
> +		ops.oobbuf = datbuf[page] + mtd->writesize;
> +		ops.len = mtd->writesize;
> +		ops.ooblen = mtd->oobsize;
> +		ops.mode = MTD_OPS_RAW;
> +		ret = mtd_write_oob(mtd, addr, &ops);
> +		if (ret < 0) {
> +			printf("Error (%d) write page %08lx\n", ret, block_off);
> +			ret = 1;
> +			goto free_memory;
> +		}
> +		block_off += mtd->writesize;
> +	}
> +
> +free_memory:
> +	for (page = 0; page < pages_per_blk ; page++) {
> +		if (datbuf[page])
> +			free(datbuf[page]);
> +	}
> +	return ret;
> +}
> +
>   static int nand_dump(struct mtd_info *mtd, ulong off, int only_oob,
>   		     int repeat)
>   {
> @@ -728,8 +842,15 @@ static int do_nand(cmd_tbl_t *cmdtp, int flag, int argc, char * const argv[])
>   	}
>   
>   	if (strcmp(cmd, "biterr") == 0) {
> -		/* todo */
> -		return 1;
> +		int bit;
> +
> +		if (argc != 4)
> +			goto usage;
> +
> +		off = (int)simple_strtoul(argv[2], NULL, 16);
> +		bit = (int)simple_strtoul(argv[3], NULL, 10);
> +		ret = nand_biterror(mtd, off, bit);
> +		return ret;
>   	}
>   
>   #ifdef CONFIG_CMD_NAND_LOCK_UNLOCK
> @@ -820,7 +941,7 @@ static char nand_help_text[] =
>   	"nand scrub [-y] off size | scrub.part partition | scrub.chip\n"
>   	"    really clean NAND erasing bad blocks (UNSAFE)\n"
>   	"nand markbad off [...] - mark bad block(s) at offset (UNSAFE)\n"
> -	"nand biterr off - make a bit error at offset (UNSAFE)"
> +	"nand biterr off bit - make a bit error at offset and bit position (UNSAFE)"
>   #ifdef CONFIG_CMD_NAND_LOCK_UNLOCK
>   	"\n"
>   	"nand lock [tight] [status]\n"
>