Commit 9748fff9 authored by pekon gupta's avatar pekon gupta Committed by Brian Norris
Browse files

mtd: nand: omap: add support for BCH16_ECC - NAND driver updates 



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: default avatarPekon Gupta <pekon@ti.com>
Signed-off-by: default avatarBrian Norris <computersforpeace@gmail.com>
parent 2be589e4

drivers/mtd/nand/omap2.c

+94 −0
Original line number Diff line number Diff line
@@ -137,6 +137,10 @@ 
#define BADBLOCK_MARKER_LENGTH		2



#ifdef CONFIG_MTD_NAND_OMAP_BCH

static u_char bch16_vector[] = {0xf5, 0x24, 0x1c, 0xd0, 0x61, 0xb3, 0xf1, 0x55,

				0x2e, 0x2c, 0x86, 0xa3, 0xed, 0x36, 0x1b, 0x78,

				0x48, 0x76, 0xa9, 0x3b, 0x97, 0xd1, 0x7a, 0x93,

				0x07, 0x0e};

static u_char bch8_vector[] = {0xf3, 0xdb, 0x14, 0x16, 0x8b, 0xd2, 0xbe, 0xcc,

	0xac, 0x6b, 0xff, 0x99, 0x7b};

static u_char bch4_vector[] = {0x00, 0x6b, 0x31, 0xdd, 0x41, 0xbc, 0x10};
@@ -1114,6 +1118,19 @@ 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;

	}
@@ -1162,6 +1179,7 @@ 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;
@@ -1201,6 +1219,41 @@ 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;

		}
@@ -1227,6 +1280,8 @@ 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;

		}
@@ -1318,6 +1373,10 @@ static int omap_elm_correct_data(struct mtd_info *mtd, u_char *data, 
		actual_eccbytes = ecc->bytes - 1;

		erased_ecc_vec = bch8_vector;

		break;

	case OMAP_ECC_BCH16_CODE_HW:

		actual_eccbytes = ecc->bytes;

		erased_ecc_vec = bch16_vector;

		break;

	default:

		pr_err("invalid driver configuration\n");

		return -EINVAL;
@@ -1401,6 +1460,7 @@ 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:
@@ -1912,6 +1972,40 @@ 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;

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