[U-Boot] [PATCH v3 3/5] mtd: nand: omap: optimize chip->ecc.calculate() for H/W ECC schemes

Pekon Gupta pekon at ti.com
Thu Aug 29 12:56:43 CEST 2013


chip->ecc.calculate() is used for calculating and fetching of ECC syndrome by
processing the data passed during Read/Write accesses.

All H/W based ECC schemes use GPMC controller to calculate ECC syndrome.
But each BCHx_ECC scheme has its own implemetation of post-processing and
fetching ECC syndrome from GPMC controller.

This patch updates OMAP_ECC_BCH8_CODE_HW ECC scheme in following way:
- merges multiple chip->calculate API for different ECC schemes
  omap_calculate_ecc() + omap_calculate_ecc_bch() + omap_calculate_ecc_bch_sw()
				==> omap_calculate_ecc()
- removes omap_ecc_disable() and instead uses it as inline.

Signed-off-by: Pekon Gupta <pekon at ti.com>
---
 drivers/mtd/nand/omap_gpmc.c | 215 ++++++++++++-------------------------------
 1 file changed, 61 insertions(+), 154 deletions(-)

diff --git a/drivers/mtd/nand/omap_gpmc.c b/drivers/mtd/nand/omap_gpmc.c
index 0af4fa4..e914c73 100644
--- a/drivers/mtd/nand/omap_gpmc.c
+++ b/drivers/mtd/nand/omap_gpmc.c
@@ -143,42 +143,6 @@ static int __maybe_unused omap_correct_data(struct mtd_info *mtd, uint8_t *dat,
 }
 
 /*
- *  omap_calculate_ecc - Generate non-inverted ECC bytes.
- *
- *  Using noninverted ECC can be considered ugly since writing a blank
- *  page ie. padding will clear the ECC bytes. This is no problem as
- *  long nobody is trying to write data on the seemingly unused page.
- *  Reading an erased page will produce an ECC mismatch between
- *  generated and read ECC bytes that has to be dealt with separately.
- *  E.g. if page is 0xFF (fresh erased), and if HW ECC engine within GPMC
- *  is used, the result of read will be 0x0 while the ECC offsets of the
- *  spare area will be 0xFF which will result in an ECC mismatch.
- *  @mtd:	MTD structure
- *  @dat:	unused
- *  @ecc_code:	ecc_code buffer
- */
-static int __maybe_unused omap_calculate_ecc(struct mtd_info *mtd,
-		const uint8_t *dat, uint8_t *ecc_code)
-{
-	u_int32_t val;
-
-	/* Start Reading from HW ECC1_Result = 0x200 */
-	val = readl(&gpmc_cfg->ecc1_result);
-
-	ecc_code[0] = val & 0xFF;
-	ecc_code[1] = (val >> 16) & 0xFF;
-	ecc_code[2] = ((val >> 8) & 0x0F) | ((val >> 20) & 0xF0);
-
-	/*
-	 * Stop reading anymore ECC vals and clear old results
-	 * enable will be called if more reads are required
-	 */
-	writel(0x000, &gpmc_cfg->ecc_config);
-
-	return 0;
-}
-
-/*
  * Generic BCH interface
  */
 struct nand_bch_priv {
@@ -281,54 +245,77 @@ static void omap_enable_hwecc(struct mtd_info *mtd, int32_t mode)
 }
 
 /*
- * omap_ecc_disable - Disable H/W ECC calculation
- *
- * @mtd:	MTD device structure
- */
-static void __maybe_unused omap_ecc_disable(struct mtd_info *mtd)
-{
-	writel((readl(&gpmc_cfg->ecc_config) & ~0x1), &gpmc_cfg->ecc_config);
-}
-
-/*
- * BCH support using ELM module
- */
-/*
- * omap_read_bch8_result - Read BCH result for BCH8 level
+ *  omap_calculate_ecc - Read ECC result
+ *  @mtd:	MTD structure
+ *  @dat:	unused
+ *  @ecc_code:	ecc_code buffer
  *
- * @mtd:	MTD device structure
- * @big_endian:	When set read register 3 first
- * @ecc_code:	Read syndrome from BCH result registers
+ *  Using noninverted ECC can be considered ugly since writing a blank
+ *  page ie. padding will clear the ECC bytes. This is no problem as
+ *  long nobody is trying to write data on the seemingly unused page.
+ *  Reading an erased page will produce an ECC mismatch between
+ *  generated and read ECC bytes that has to be dealt with separately.
+ *  E.g. if page is 0xFF (fresh erased), and if HW ECC engine within GPMC
+ *  is used, the result of read will be 0x0 while the ECC offsets of the
+ *  spare area will be 0xFF which will result in an ECC mismatch.
  */
-static void omap_read_bch8_result(struct mtd_info *mtd, uint8_t big_endian,
+static int omap_calculate_ecc(struct mtd_info *mtd, const uint8_t *dat,
 				uint8_t *ecc_code)
 {
-	uint32_t *ptr;
+	struct nand_chip *chip = mtd->priv;
+	struct nand_bch_priv *bch = chip->priv;
+	uint32_t *ptr, val = 0;
 	int8_t i = 0, j;
 
-	if (big_endian) {
+	switch (bch->ecc_scheme) {
+	case OMAP_ECC_HAM1_CODE_HW_ROMCODE:
+		val = readl(&gpmc_cfg->ecc1_result);
+		ecc_code[0] = val & 0xFF;
+		ecc_code[1] = (val >> 16) & 0xFF;
+		ecc_code[2] = ((val >> 8) & 0x0F) | ((val >> 20) & 0xF0);
+		break;
+#ifdef CONFIG_BCH
+	case OMAP_ECC_BCH8_CODE_HW_DETECTION_SW:
+		val	= readl(&gpmc_cfg->bch_result_0_3[0].bch_result_x[3]);
+		*ecc_code++ = 0xef ^ (val & 0xFF);
+		val	= readl(&gpmc_cfg->bch_result_0_3[0].bch_result_x[2]);
+		*ecc_code++ = 0x51 ^ ((val >> 24) & 0xFF);
+		*ecc_code++ = 0x2e ^ ((val >> 16) & 0xFF);
+		*ecc_code++ = 0x09 ^ ((val >>  8) & 0xFF);
+		*ecc_code++ = 0xed ^ ((val >>  0) & 0xFF);
+		val	= readl(&gpmc_cfg->bch_result_0_3[0].bch_result_x[1]);
+		*ecc_code++ = 0x93 ^ ((val >> 24) & 0xFF);
+		*ecc_code++ = 0x9a ^ ((val >> 16) & 0xFF);
+		*ecc_code++ = 0xc2 ^ ((val >>  8) & 0xFF);
+		*ecc_code++ = 0x97 ^ ((val >>  0) & 0xFF);
+		val	= readl(&gpmc_cfg->bch_result_0_3[0].bch_result_x[0]);
+		*ecc_code++ = 0x79 ^ ((val >> 24) & 0xFF);
+		*ecc_code++ = 0xe5 ^ ((val >> 16) & 0xFF);
+		*ecc_code++ = 0x24 ^ ((val >>  8) & 0xFF);
+		*ecc_code++ = 0xb5 ^ ((val >>  0) & 0xFF);
+		break;
+#endif
+	case OMAP_ECC_BCH8_CODE_HW:
 		ptr = &gpmc_cfg->bch_result_0_3[0].bch_result_x[3];
-		ecc_code[i++] = readl(ptr) & 0xFF;
+		val = readl(ptr);
+		ecc_code[i++] = (val >>  0) & 0xFF;
 		ptr--;
 		for (j = 0; j < 3; j++) {
-			ecc_code[i++] = (readl(ptr) >> 24) & 0xFF;
-			ecc_code[i++] = (readl(ptr) >> 16) & 0xFF;
-			ecc_code[i++] = (readl(ptr) >>  8) & 0xFF;
-			ecc_code[i++] = readl(ptr) & 0xFF;
+			val = readl(ptr);
+			ecc_code[i++] = (val >> 24) & 0xFF;
+			ecc_code[i++] = (val >> 16) & 0xFF;
+			ecc_code[i++] = (val >>  8) & 0xFF;
+			ecc_code[i++] = (val >>  0) & 0xFF;
 			ptr--;
 		}
-	} else {
-		ptr = &gpmc_cfg->bch_result_0_3[0].bch_result_x[0];
-		for (j = 0; j < 3; j++) {
-			ecc_code[i++] = readl(ptr) & 0xFF;
-			ecc_code[i++] = (readl(ptr) >>  8) & 0xFF;
-			ecc_code[i++] = (readl(ptr) >> 16) & 0xFF;
-			ecc_code[i++] = (readl(ptr) >> 24) & 0xFF;
-			ptr++;
-		}
-		ecc_code[i++] = readl(ptr) & 0xFF;
-		ecc_code[i++] = 0;	/* 14th byte is always zero */
+		break;
+	default:
+		printf("nand: error: invalid driver configuration\n");
+		return -EINVAL;
 	}
+	/* clear result and disable engine */
+	writel((readl(&gpmc_cfg->ecc_config) & ~0x1), &gpmc_cfg->ecc_config);
+	return 0;
 }
 
 /*
@@ -367,35 +354,6 @@ static void omap_rotate_ecc_bch(struct mtd_info *mtd, uint8_t *calc_ecc,
 }
 
 /*
- *  omap_calculate_ecc_bch - Read BCH ECC result
- *
- *  @mtd:	MTD structure
- *  @dat:	unused
- *  @ecc_code:	ecc_code buffer
- */
-static int omap_calculate_ecc_bch(struct mtd_info *mtd, const uint8_t *dat,
-				uint8_t *ecc_code)
-{
-	struct nand_chip *chip = mtd->priv;
-	struct nand_bch_priv *bch = chip->priv;
-	uint8_t big_endian = 1;
-	int8_t ret = 0;
-
-	if (bch->type == ECC_BCH8)
-		omap_read_bch8_result(mtd, big_endian, ecc_code);
-	else /* BCH4 and BCH16 currently not supported */
-		ret = -1;
-
-	/*
-	 * Stop reading anymore ECC vals and clear old results
-	 * enable will be called if more reads are required
-	 */
-	omap_ecc_disable(mtd);
-
-	return ret;
-}
-
-/*
  * omap_fix_errors_bch - Correct bch error in the data
  *
  * @mtd:	MTD device structure
@@ -550,57 +508,6 @@ static int omap_read_page_bch(struct mtd_info *mtd, struct nand_chip *chip,
  * OMAP3 BCH8 support (with BCH library)
  */
 #ifdef CONFIG_BCH
-/*
- *  omap_calculate_ecc_bch_sw - Read BCH ECC result
- *
- *  @mtd:	MTD device structure
- *  @dat:	The pointer to data on which ecc is computed (unused here)
- *  @ecc:	The ECC output buffer
- */
-static int omap_calculate_ecc_bch_sw(struct mtd_info *mtd, const uint8_t *dat,
-				uint8_t *ecc)
-{
-	int ret = 0;
-	size_t i;
-	unsigned long nsectors, val1, val2, val3, val4;
-
-	nsectors = ((readl(&gpmc_cfg->ecc_config) >> 4) & 0x7) + 1;
-
-	for (i = 0; i < nsectors; i++) {
-		/* Read hw-computed remainder */
-		val1 = readl(&gpmc_cfg->bch_result_0_3[i].bch_result_x[0]);
-		val2 = readl(&gpmc_cfg->bch_result_0_3[i].bch_result_x[1]);
-		val3 = readl(&gpmc_cfg->bch_result_0_3[i].bch_result_x[2]);
-		val4 = readl(&gpmc_cfg->bch_result_0_3[i].bch_result_x[3]);
-
-		/*
-		 * Add constant polynomial to remainder, in order to get an ecc
-		 * sequence of 0xFFs for a buffer filled with 0xFFs.
-		 */
-		*ecc++ = 0xef ^ (val4 & 0xFF);
-		*ecc++ = 0x51 ^ ((val3 >> 24) & 0xFF);
-		*ecc++ = 0x2e ^ ((val3 >> 16) & 0xFF);
-		*ecc++ = 0x09 ^ ((val3 >> 8) & 0xFF);
-		*ecc++ = 0xed ^ (val3 & 0xFF);
-		*ecc++ = 0x93 ^ ((val2 >> 24) & 0xFF);
-		*ecc++ = 0x9a ^ ((val2 >> 16) & 0xFF);
-		*ecc++ = 0xc2 ^ ((val2 >> 8) & 0xFF);
-		*ecc++ = 0x97 ^ (val2 & 0xFF);
-		*ecc++ = 0x79 ^ ((val1 >> 24) & 0xFF);
-		*ecc++ = 0xe5 ^ ((val1 >> 16) & 0xFF);
-		*ecc++ = 0x24 ^ ((val1 >> 8) & 0xFF);
-		*ecc++ = 0xb5 ^ (val1 & 0xFF);
-	}
-
-	/*
-	 * Stop reading anymore ECC vals and clear old results
-	 * enable will be called if more reads are required
-	 */
-	omap_ecc_disable(mtd);
-
-	return ret;
-}
-
 /**
  * omap_correct_data_bch_sw - Decode received data and correct errors
  * @mtd: MTD device structure
@@ -729,7 +636,7 @@ static int omap_select_ecc_scheme(struct nand_chip *nand, int ecc_scheme,
 		nand->ecc.bytes		= 13;
 		nand->ecc.hwctl		= omap_enable_hwecc;
 		nand->ecc.correct	= omap_correct_data_bch_sw;
-		nand->ecc.calculate	= omap_calculate_ecc_bch_sw;
+		nand->ecc.calculate	= omap_calculate_ecc;
 		/* BCH SW library is used for error detection */
 		bch_priv.control	= init_bch(13, 8, 0x201b);
 		if (!bch_priv.control) {
@@ -757,7 +664,7 @@ static int omap_select_ecc_scheme(struct nand_chip *nand, int ecc_scheme,
 		nand->ecc.read_page	= omap_read_page_bch;
 		nand->ecc.hwctl		= omap_enable_hwecc;
 		nand->ecc.correct	= omap_correct_data_bch;
-		nand->ecc.calculate	= omap_calculate_ecc_bch;
+		nand->ecc.calculate	= omap_calculate_ecc;
 		/* ELM is used for ECC error detection */
 		elm_init();
 		/* define ecc-layout */
-- 
1.8.1



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