[U-Boot] [PATCH v2 5/6] omap_gpmc: add support for hw assisted BCH8

Andreas Bießmann
2013-04-02T16:05:57Z

The BCH for OMAP3 is implemented as the linux kernel in
0e618ef0a6a33cf7ef96c2c824402088dd8ef48c does.

The kernel states:

---8<---
The OMAP3 GPMC hardware BCH engine computes remainder polynomials, it does not
provide automatic error location and correction: this step is implemented using
the BCH library.
--->8---

And we do so in u-boot.

This implementation uses the same layout for BCH8 but it is fix. The current
provided layout does only work with 64 Byte OOB.

Signed-off-by: Andreas Bie?mann <andreas.devel@googlemail.com>
Cc: Tom Rini <trini@ti.com>
Cc: Ilya Yanok <ilya.yanok@cogentembedded.com>
Cc: Scott Wood <scottwood@freescale.com>
Cc: Mansoor Ahamed <mansoor.ahamed@ti.com>
---
since v1:
* cleanups (remove debug stuff)
* make checkpach clean (still 2 warnings which I will not fix)
* merge some code with the AM33XX implementation

known checkpatch errors:
WARNING: line over 80 characters
#92: FILE: drivers/mtd/nand/omap_gpmc.c:273:
+static void __maybe_unused omap_hwecc_init_bch(struct nand_chip *chip, int32_t mode)

WARNING: line over 80 characters
#165: FILE: drivers/mtd/nand/omap_gpmc.c:346:
+static void __maybe_unused omap_enable_ecc_bch(struct mtd_info *mtd, int32_t mode)

total: 0 errors, 2 warnings, 0 checks, 428 lines checked

drivers/mtd/nand/omap_gpmc.c | 347 +++++++++++++++++++++++++++++++-----------
lib/Makefile | 2 +-
2 files changed, 258 insertions(+), 91 deletions(-)

diff --git a/drivers/mtd/nand/omap_gpmc.c b/drivers/mtd/nand/omap_gpmc.c
index f073cbe..5f36971 100644
--- a/drivers/mtd/nand/omap_gpmc.c
+++ b/drivers/mtd/nand/omap_gpmc.c
@@ -28,6 +28,7 @@
#include <asm/arch/cpu.h>
#include <asm/omap_gpmc.h>
#include <linux/mtd/nand_ecc.h>
+#include <linux/bch.h>
#include <linux/compiler.h>
#include <nand.h>
#ifdef CONFIG_AM33XX
@@ -37,6 +38,8 @@
static uint8_t cs;
static __maybe_unused struct nand_ecclayout hw_nand_oob =
GPMC_NAND_HW_ECC_LAYOUT;
+static __maybe_unused struct nand_ecclayout hw_bch8_nand_oob =
+ GPMC_NAND_HW_BCH8_ECC_LAYOUT;

/*
* omap_nand_hwcontrol - Set the address pointers corretly for the
@@ -239,13 +242,13 @@ static void __maybe_unused omap_enable_hwecc(struct mtd_info *mtd, int32_t mode)
}

/*
- * BCH8 support (needs ELM and thus AM33xx-only)
+ * Generic BCH interface
*/
-#ifdef CONFIG_AM33XX
struct nand_bch_priv {
uint8_t mode;
uint8_t type;
uint8_t nibbles;
+ struct bch_control *control;
};

/* bch types */
@@ -253,21 +256,127 @@ struct nand_bch_priv {
#define ECC_BCH8 1
#define ECC_BCH16 2

+/* GPMC ecc engine settings */
+#define BCH_WRAPMODE_1 1 /* BCH wrap mode 1 */
+#define BCH_WRAPMODE_6 6 /* BCH wrap mode 6 */
+
/* BCH nibbles for diff bch levels */
#define NAND_ECC_HW_BCH ((uint8_t)(NAND_ECC_HW_OOB_FIRST) + 1)
#define ECC_BCH4_NIBBLES 13
#define ECC_BCH8_NIBBLES 26
#define ECC_BCH16_NIBBLES 52

-static struct nand_ecclayout hw_bch8_nand_oob = GPMC_NAND_HW_BCH8_ECC_LAYOUT;
-
-static struct nand_bch_priv bch_priv = {
+static __maybe_unused struct nand_bch_priv bch_priv = {
.mode = NAND_ECC_HW_BCH,
.type = ECC_BCH8,
- .nibbles = ECC_BCH8_NIBBLES
+ .nibbles = ECC_BCH8_NIBBLES,
+ .control = NULL
};

/*
+ * omap_hwecc_init_bch - Initialize the BCH Hardware ECC for NAND flash in
+ * GPMC controller
+ * @mtd: MTD device structure
+ * @mode: Read/Write mode
+ */
+static void __maybe_unused omap_hwecc_init_bch(struct nand_chip *chip, int32_t mode)
+{
+ uint32_t val;
+ uint32_t dev_width = (chip->options & NAND_BUSWIDTH_16) >> 1;
+#ifdef CONFIG_AM33XX
+ uint32_t unused_length = 0;
+#endif
+ uint32_t wr_mode = BCH_WRAPMODE_6;
+ struct nand_bch_priv *bch = chip->priv;
+
+ /* Clear the ecc result registers, select ecc reg as 1 */
+ writel(ECCCLEAR | ECCRESULTREG1, &gpmc_cfg->ecc_control);
+
+#ifdef CONFIG_AM33XX
+ wr_mode = BCH_WRAPMODE_1;
+
+ switch (bch->nibbles) {
+ case ECC_BCH4_NIBBLES:
+ unused_length = 3;
+ break;
+ case ECC_BCH8_NIBBLES:
+ unused_length = 2;
+ break;
+ case ECC_BCH16_NIBBLES:
+ unused_length = 0;
+ break;
+ }
+
+ switch (mode) {
+ case NAND_ECC_WRITE:
+ /* eccsize1 config */
+ val = ((unused_length + bch->nibbles) << 22);
+ break;
+
+ case NAND_ECC_READ:
+ default:
+ /* by default eccsize0 selected for ecc1resultsize */
+ /* eccsize0 config */
+ val = (bch->nibbles << 12);
+ /* eccsize1 config */
+ val |= (unused_length << 22);
+ break;
+ }
+#else
+ /*
+ * This is for BCH sw library, we need to choose wrap mode 6 and fixed
+ * layout.
+ * Here we are using wrapping mode 6 both for reading and writing, with:
+ * size0 = 0 (no additional protected byte in spare area)
+ * size1 = 32 (skip 32 nibbles = 16 bytes per sector in spare area)
+ */
+ val = (32 << 22) | (0 << 12);
+#endif
+ /* ecc size configuration */
+ writel(val, &gpmc_cfg->ecc_size_config);
+
+ /* by default 512bytes sector page is selected */
+ /* set bch mode */
+ val = (1 << 16);
+ /* bch4 / bch8 / bch16 */
+ val |= (bch->type << 12);
+ val |= (wr_mode << 8);
+ val |= (dev_width << 7);
+ val |= (cs << 1);
+ debug("set ECC_CONFIG=0x%08x\n", val);
+ writel(val, &gpmc_cfg->ecc_config);
+}
+
+/*
+ * omap_enable_ecc_bch - This function enables the bch h/w ecc functionality
+ * @mtd: MTD device structure
+ * @mode: Read/Write mode
+ */
+static void __maybe_unused omap_enable_ecc_bch(struct mtd_info *mtd, int32_t mode)
+{
+ struct nand_chip *chip = mtd->priv;
+
+ omap_hwecc_init_bch(chip, mode);
+ /* enable ecc */
+ writel((readl(&gpmc_cfg->ecc_config) | 0x1), &gpmc_cfg->ecc_config);
+}
+
+/*
+ * 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);
+}
+
+/*
+ * BCH8 support (needs ELM and thus AM33xx-only)
+ */
+#ifdef CONFIG_AM33XX
+
+/*
* omap_read_bch8_result - Read BCH result for BCH8 level
*
* @mtd: MTD device structure
@@ -306,18 +415,6 @@ static void omap_read_bch8_result(struct mtd_info *mtd, uint8_t big_endian,
}

/*
- * omap_ecc_disable - Disable H/W ECC calculation
- *
- * @mtd: MTD device structure
- *
- */
-static void omap_ecc_disable(struct mtd_info *mtd)
-{
- writel((readl(&gpmc_cfg->ecc_config) & ~0x1),
- &gpmc_cfg->ecc_config);
-}
-
-/*
* omap_rotate_ecc_bch - Rotate the syndrome bytes
*
* @mtd: MTD device structure
@@ -468,76 +565,7 @@ static int omap_correct_data_bch(struct mtd_info *mtd, uint8_t *dat,

return 0;
}
-/*
- * omap_hwecc_init_bch - Initialize the BCH Hardware ECC for NAND flash in
- * GPMC controller
- * @mtd: MTD device structure
- * @mode: Read/Write mode
- */
-static void omap_hwecc_init_bch(struct nand_chip *chip, int32_t mode)
-{
- uint32_t val, dev_width = (chip->options & NAND_BUSWIDTH_16) >> 1;
- uint32_t unused_length = 0;
- struct nand_bch_priv *bch = chip->priv;
-
- switch (bch->nibbles) {
- case ECC_BCH4_NIBBLES:
- unused_length = 3;
- break;
- case ECC_BCH8_NIBBLES:
- unused_length = 2;
- break;
- case ECC_BCH16_NIBBLES:
- unused_length = 0;
- break;
- }
-
- /* Clear the ecc result registers, select ecc reg as 1 */
- writel(ECCCLEAR | ECCRESULTREG1, &gpmc_cfg->ecc_control);
-
- switch (mode) {
- case NAND_ECC_WRITE:
- /* eccsize1 config */
- val = ((unused_length + bch->nibbles) << 22);
- break;
-
- case NAND_ECC_READ:
- default:
- /* by default eccsize0 selected for ecc1resultsize */
- /* eccsize0 config */
- val = (bch->nibbles << 12);
- /* eccsize1 config */
- val |= (unused_length << 22);
- break;
- }
- /* ecc size configuration */
- writel(val, &gpmc_cfg->ecc_size_config);
- /* by default 512bytes sector page is selected */
- /* set bch mode */
- val = (1 << 16);
- /* bch4 / bch8 / bch16 */
- val |= (bch->type << 12);
- /* set wrap mode to 1 */
- val |= (1 << 8);
- val |= (dev_width << 7);
- val |= (cs << 1);
- writel(val, &gpmc_cfg->ecc_config);
-}

-/*
- * omap_enable_ecc_bch- This function enables the bch h/w ecc functionality
- * @mtd: MTD device structure
- * @mode: Read/Write mode
- *
- */
-static void omap_enable_ecc_bch(struct mtd_info *mtd, int32_t mode)
-{
- struct nand_chip *chip = mtd->priv;
-
- omap_hwecc_init_bch(chip, mode);
- /* enable ecc */
- writel((readl(&gpmc_cfg->ecc_config) | 0x1), &gpmc_cfg->ecc_config);
-}

/**
* omap_read_page_bch - hardware ecc based page read function
@@ -602,6 +630,127 @@ static int omap_read_page_bch(struct mtd_info *mtd, struct nand_chip *chip,
}
#endif /* CONFIG_AM33XX */

+/*
+ * basic BCH8 support
+ */
+#ifdef CONFIG_NAND_OMAP_BCH8
+/*
+ * omap_calculate_ecc_bch - 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(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 - Decode received data and correct errors
+ * @mtd: MTD device structure
+ * @data: page data
+ * @read_ecc: ecc read from nand flash
+ * @calc_ecc: ecc read from HW ECC registers
+ */
+static int omap_correct_data_bch(struct mtd_info *mtd, u_char *data,
+ u_char *read_ecc, u_char *calc_ecc)
+{
+ int i, count;
+ /* cannot correct more than 8 errors */
+ unsigned int errloc[8];
+ struct nand_chip *chip = mtd->priv;
+ struct nand_bch_priv *chip_priv = chip->priv;
+ struct bch_control *bch = chip_priv->control;
+
+ count = decode_bch(bch, NULL, 512, read_ecc, calc_ecc, NULL, errloc);
+ if (count > 0) {
+ /* correct errors */
+ for (i = 0; i < count; i++) {
+ /* correct data only, not ecc bytes */
+ if (errloc[i] < 8*512)
+ data[errloc[i]/8] ^= 1 << (errloc[i] & 7);
+ printf("corrected bitflip %u\n", errloc[i]);
+#ifdef DEBUG
+ puts("read_ecc: ");
+ /*
+ * BCH8 have 13 bytes of ECC; BCH4 needs adoption
+ * here!
+ */
+ for (i = 0; i < 13; i++)
+ printf("%02x ", read_ecc[i]);
+ puts("\n");
+ puts("calc_ecc: ");
+ for (i = 0; i < 13; i++)
+ printf("%02x ", calc_ecc[i]);
+ puts("\n");
+#endif
+ }
+ } else if (count < 0) {
+ puts("ecc unrecoverable error\n");
+ }
+ return count;
+}
+
+/**
+ * omap_free_bch - Release BCH ecc resources
+ * @mtd: MTD device structure
+ */
+static void __maybe_unused omap_free_bch(struct mtd_info *mtd)
+{
+ struct nand_chip *chip = mtd->priv;
+ struct nand_bch_priv *chip_priv = chip->priv;
+ struct bch_control *bch = NULL;
+
+ if (chip_priv)
+ bch = chip_priv->control;
+
+ if (bch) {
+ free_bch(bch);
+ chip_priv->control = NULL;
+ }
+}
+#endif /* CONFIG_NAND_OMAP_BCH8 */
+
#ifndef CONFIG_SPL_BUILD
/*
* omap_nand_switch_ecc - switch the ECC operation between different engines
@@ -650,13 +799,17 @@ void omap_nand_switch_ecc(uint32_t hardware, uint32_t eccstrength)
omap_hwecc_init(nand);
printf("1-bit hamming HW ECC selected\n");
}
-#ifdef CONFIG_AM33XX
+#if defined(CONFIG_AM33XX) || defined(CONFIG_NAND_OMAP_BCH8)
else if (eccstrength == 8) {
nand->ecc.mode = NAND_ECC_HW;
nand->ecc.layout = &hw_bch8_nand_oob;
nand->ecc.size = 512;
+#ifdef CONFIG_AM33XX
nand->ecc.bytes = 14;
nand->ecc.read_page = omap_read_page_bch;
+#else
+ nand->ecc.bytes = 13;
+#endif
nand->ecc.hwctl = omap_enable_ecc_bch;
nand->ecc.correct = omap_correct_data_bch;
nand->ecc.calculate = omap_calculate_ecc_bch;
@@ -736,16 +889,28 @@ int board_nand_init(struct nand_chip *nand)

nand->chip_delay = 100;

+#if defined(CONFIG_AM33XX) || defined(CONFIG_NAND_OMAP_BCH8)
#ifdef CONFIG_AM33XX
+ /* AM33xx uses the ELM */
/* required in case of BCH */
elm_init();
-
+#else
+ /*
+ * Whereas other OMAP based SoC do not have the ELM, they use the BCH
+ * SW library.
+ */
+ bch_priv.control = init_bch(13, 8, 0x201b /* hw polynominal */);
+ if (!bch_priv.control) {
+ puts("Could not init_bch()\n");
+ return -ENODEV;
+ }
+#endif
/* BCH info that will be correct for SPL or overridden otherwise. */
nand->priv = &bch_priv;
#endif

/* Default ECC mode */
-#ifdef CONFIG_AM33XX
+#if defined(CONFIG_AM33XX) || defined(CONFIG_NAND_OMAP_BCH8)
nand->ecc.mode = NAND_ECC_HW;
nand->ecc.layout = &hw_bch8_nand_oob;
nand->ecc.size = CONFIG_SYS_NAND_ECCSIZE;
@@ -753,7 +918,9 @@ int board_nand_init(struct nand_chip *nand)
nand->ecc.hwctl = omap_enable_ecc_bch;
nand->ecc.correct = omap_correct_data_bch;
nand->ecc.calculate = omap_calculate_ecc_bch;
+#ifdef CONFIG_AM33XX
nand->ecc.read_page = omap_read_page_bch;
+#endif
omap_hwecc_init_bch(nand, NAND_ECC_READ);
#else
#if !defined(CONFIG_SPL_BUILD) || defined(CONFIG_SPL_NAND_SOFTECC)
diff --git a/lib/Makefile b/lib/Makefile
index 1bfd3ee..5d71b80 100644
--- a/lib/Makefile
+++ b/lib/Makefile
@@ -27,7 +27,6 @@ LIB = $(obj)libgeneric.o

ifndef CONFIG_SPL_BUILD
COBJS-$(CONFIG_ADDR_MAP) += addr_map.o
-COBJS-$(CONFIG_BCH) += bch.o
COBJS-$(CONFIG_AES) += aes.o
COBJS-$(CONFIG_BZIP2) += bzlib.o
COBJS-$(CONFIG_BZIP2) += bzlib_crctable.o
@@ -67,6 +66,7 @@ COBJS-$(CONFIG_SPL_NET_SUPPORT) += errno.o
COBJS-$(CONFIG_SPL_NET_SUPPORT) += hashtable.o
COBJS-$(CONFIG_SPL_NET_SUPPORT) += net_utils.o
endif
+COBJS-$(CONFIG_BCH) += bch.o
COBJS-y += crc32.o
COBJS-y += ctype.o
COBJS-y += div64.o
--
1.7.10.4