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/%5C 1325691123-19565-1-git-send-email-holger.brunck@keymile.com

The implementation is inspired from 'mtd-utils/nand-utils/nandflipbits.c'

Signed-off-by: Balamanikandan Gunasundar balamanikandan.gunasundar@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"