This patch add support for BCH16 ecc-scheme in OMAP NAND driver, by extending
following functions:
- omap_enable_hwecc (nand_chip->ecc.hwctl): configure GPMC controller
- omap_calculate_ecc_bch (nand_chip->ecc.calculate): fetch ECC signature from GPMC controller
- omap_elm_correct_data (nand_chip->ecc.correct): detect and correct ECC errors using ELM
(a) BCH16 ecc-scheme can detect and correct 16 bit-flips per 512Bytes of data.
(b) BCH16 ecc-scheme generates 26-bytes of ECC syndrome / 512B.
Due to (b) this scheme can only be used with NAND devices which have enough
OOB to satisfy the relation: "OOBsize per page >= 26 * (page-size / 512)"
Signed-off-by: Pekon Gupta <pekon@xxxxxx>
---
drivers/mtd/nand/omap2.c | 89 ++++++++++++++++++++++++++++++++++++++++++++++++
1 file changed, 89 insertions(+)
diff --git a/drivers/mtd/nand/omap2.c b/drivers/mtd/nand/omap2.c
index 369aee7..dd48b94 100644
--- a/drivers/mtd/nand/omap2.c
+++ b/drivers/mtd/nand/omap2.c
@@ -1110,6 +1110,19 @@ static void __maybe_unused omap_enable_hwecc_bch(struct mtd_info *mtd, int mode)
ecc_size1 = BCH_ECC_SIZE1;
}
break;
+ case OMAP_ECC_BCH16_CODE_HW:
+ bch_type = 0x2;
+ nsectors = chip->ecc.steps;
+ if (mode == NAND_ECC_READ) {
+ wr_mode = 0x01;
+ ecc_size0 = 52; /* ECC bits in nibbles per sector */
+ ecc_size1 = 0; /* non-ECC bits in nibbles per sector */
+ } else {
+ wr_mode = 0x01;
+ ecc_size0 = 0; /* extra bits in nibbles per sector */
+ ecc_size1 = 52; /* OOB bits in nibbles per sector */
+ }
+ break;
default:
return;
}
@@ -1158,6 +1171,7 @@ static int __maybe_unused omap_calculate_ecc_bch(struct mtd_info *mtd,
struct gpmc_nand_regs *gpmc_regs = &info->reg;
u8 *ecc_code;
unsigned long nsectors, bch_val1, bch_val2, bch_val3, bch_val4;
+ u32 val;
int i;
nsectors = ((readl(info->reg.gpmc_ecc_config) >> 4) & 0x7) + 1;
@@ -1197,6 +1211,41 @@ static int __maybe_unused omap_calculate_ecc_bch(struct mtd_info *mtd,
*ecc_code++ = ((bch_val1 >> 4) & 0xFF);
*ecc_code++ = ((bch_val1 & 0xF) << 4);
break;
+ case OMAP_ECC_BCH16_CODE_HW:
+ val = readl(gpmc_regs->gpmc_bch_result6[i]);
+ ecc_code[0] = ((val >> 8) & 0xFF);
+ ecc_code[1] = ((val >> 0) & 0xFF);
+ val = readl(gpmc_regs->gpmc_bch_result5[i]);
+ ecc_code[2] = ((val >> 24) & 0xFF);
+ ecc_code[3] = ((val >> 16) & 0xFF);
+ ecc_code[4] = ((val >> 8) & 0xFF);
+ ecc_code[5] = ((val >> 0) & 0xFF);
+ val = readl(gpmc_regs->gpmc_bch_result4[i]);
+ ecc_code[6] = ((val >> 24) & 0xFF);
+ ecc_code[7] = ((val >> 16) & 0xFF);
+ ecc_code[8] = ((val >> 8) & 0xFF);
+ ecc_code[9] = ((val >> 0) & 0xFF);
+ val = readl(gpmc_regs->gpmc_bch_result3[i]);
+ ecc_code[10] = ((val >> 24) & 0xFF);
+ ecc_code[11] = ((val >> 16) & 0xFF);
+ ecc_code[12] = ((val >> 8) & 0xFF);
+ ecc_code[13] = ((val >> 0) & 0xFF);
+ val = readl(gpmc_regs->gpmc_bch_result2[i]);
+ ecc_code[14] = ((val >> 24) & 0xFF);
+ ecc_code[15] = ((val >> 16) & 0xFF);
+ ecc_code[16] = ((val >> 8) & 0xFF);
+ ecc_code[17] = ((val >> 0) & 0xFF);
+ val = readl(gpmc_regs->gpmc_bch_result1[i]);
+ ecc_code[18] = ((val >> 24) & 0xFF);
+ ecc_code[19] = ((val >> 16) & 0xFF);
+ ecc_code[20] = ((val >> 8) & 0xFF);
+ ecc_code[21] = ((val >> 0) & 0xFF);
+ val = readl(gpmc_regs->gpmc_bch_result0[i]);
+ ecc_code[22] = ((val >> 24) & 0xFF);
+ ecc_code[23] = ((val >> 16) & 0xFF);
+ ecc_code[24] = ((val >> 8) & 0xFF);
+ ecc_code[25] = ((val >> 0) & 0xFF);
+ break;
default:
return -EINVAL;
}
@@ -1223,6 +1272,8 @@ static int __maybe_unused omap_calculate_ecc_bch(struct mtd_info *mtd,
/* Set 14th ECC byte as 0x0 for ROM compatibility */
ecc_calc[eccbytes - 1] = 0x0;
break;
+ case OMAP_ECC_BCH16_CODE_HW:
+ break;
default:
return -EINVAL;
}
@@ -1296,6 +1347,9 @@ static int omap_elm_correct_data(struct mtd_info *mtd, u_char *data,
/* omit 14th ECC byte reserved for ROM code compatibility */
actual_eccbytes = ecc->bytes - 1;
break;
+ case OMAP_ECC_BCH16_CODE_HW:
+ actual_eccbytes = ecc->bytes;
+ break;
default:
pr_err("invalid driver configuration\n");
return -EINVAL;
@@ -1408,6 +1462,7 @@ static int omap_elm_correct_data(struct mtd_info *mtd, u_char *data,
BCH4_BIT_PAD;
break;
case OMAP_ECC_BCH8_CODE_HW:
+ case OMAP_ECC_BCH16_CODE_HW:
pos = err_vec[i].error_loc[j];
break;
default:
@@ -1935,6 +1990,40 @@ static int omap_nand_probe(struct platform_device *pdev)
goto return_error;
#endif
+ case OMAP_ECC_BCH16_CODE_HW:
+#ifdef CONFIG_MTD_NAND_OMAP_BCH
+ pr_info("using OMAP_ECC_BCH16_CODE_HW ECC scheme\n");
+ nand_chip->ecc.mode = NAND_ECC_HW;
+ nand_chip->ecc.size = 512;
+ nand_chip->ecc.bytes = 26;
+ nand_chip->ecc.strength = 16;
+ nand_chip->ecc.hwctl = omap_enable_hwecc_bch;
+ nand_chip->ecc.correct = omap_elm_correct_data;
+ nand_chip->ecc.calculate = omap_calculate_ecc_bch;
+ nand_chip->ecc.read_page = omap_read_page_bch;
+ nand_chip->ecc.write_page = omap_write_page_bch;
+ /* This ECC scheme requires ELM H/W block */
+ err = is_elm_present(info, pdata->elm_of_node, BCH16_ECC);
+ if (err < 0) {
+ pr_err("ELM is required for this ECC scheme\n");
+ goto return_error;
+ }
+ /* define ECC layout */
+ ecclayout->eccbytes = nand_chip->ecc.bytes *
+ (mtd->writesize /
+ nand_chip->ecc.size);
+ oob_index = BADBLOCK_MARKER_LENGTH;
+ for (i = 0; i < ecclayout->eccbytes; i++, oob_index++)
+ ecclayout->eccpos[i] = oob_index;
+ /* reserved marker already included in ecclayout->eccbytes */
+ ecclayout->oobfree->offset =
+ ecclayout->eccpos[ecclayout->eccbytes - 1] + 1;
+ break;
+#else
+ pr_err("nand: error: CONFIG_MTD_NAND_OMAP_BCH not enabled\n");
+ err = -EINVAL;
+ goto return_error;
+#endif
default:
pr_err("nand: error: invalid or unsupported ECC scheme\n");
err = -EINVAL;
--
1.8.5.1.163.gd7aced9
--
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