This patch adds following two flavours of BCH4 ECC scheme in omap2-nand driver
- OMAP_ECC_BCH4_CODE_HW_DETECTION_SW
- uses GPMC H/W engine for calculating ECC.
- uses software library (lib/bch.h & nand_bch.h) for error correction.
- OMAP_ECC_BCH4_CODE_HW
- uses GPMC H/W engine for calculating ECC.
- uses ELM H/W engine for error correction.
With this patch omap2-nand driver supports following ECC schemes:
+---------------------------------------+---------------+---------------+
| ECC scheme |ECC calculation|Error detection|
+---------------------------------------+---------------+---------------+
|OMAP_ECC_HAM1_CODE_HW |H/W (GPMC) |S/W |
+---------------------------------------+---------------+---------------+
|OMAP_ECC_BCH4_CODE_HW_DETECTION_SW |H/W (GPMC) |S/W (lib/bch.h)|
|OMAP_ECC_BCH4_CODE_HW |H/W (GPMC) |H/W (ELM) |
+---------------------------------------+---------------+---------------+
|OMAP_ECC_BCH8_CODE_HW_DETECTION_SW |H/W (GPMC) |S/W (lib/bch.h)|
|OMAP_ECC_BCH8_CODE_HW |H/W (GPMC) |H/W (ELM) |
+---------------------------------------+---------------+---------------+
Important:
- Selection of OMAP_ECC_BCHx_CODE_HW_DETECTION_SW requires,
Kconfig: CONFIG_MTD_NAND_ECC_BCH: enables S/W based BCH ECC algorithm.
- Selection of OMAP_ECC_BCHx_CODE_HW requires,
Kconfig: CONFIG_MTD_NAND_OMAP_BCH: enables ELM H/W module.
Signed-off-by: Pekon Gupta <pekon@xxxxxx>
---
drivers/mtd/nand/Kconfig | 30 ++---------
drivers/mtd/nand/omap2.c | 134 +++++++++++++++++++++--------------------------
2 files changed, 63 insertions(+), 101 deletions(-)
diff --git a/drivers/mtd/nand/Kconfig b/drivers/mtd/nand/Kconfig
index d885298..5836039 100644
--- a/drivers/mtd/nand/Kconfig
+++ b/drivers/mtd/nand/Kconfig
@@ -96,35 +96,13 @@ config MTD_NAND_OMAP2
config MTD_NAND_OMAP_BCH
depends on MTD_NAND && MTD_NAND_OMAP2 && ARCH_OMAP3
- tristate "Enable support for hardware BCH error correction"
+ tristate "Support hardware based BCH error correction"
default n
select BCH
- select BCH_CONST_PARAMS
help
- Support for hardware BCH error correction.
-
-choice
- prompt "BCH error correction capability"
- depends on MTD_NAND_OMAP_BCH
-
-config MTD_NAND_OMAP_BCH8
- bool "8 bits / 512 bytes (recommended)"
- help
- Support correcting up to 8 bitflips per 512-byte block.
- This will use 13 bytes of spare area per 512 bytes of page data.
- This is the recommended mode, as 4-bit mode does not work
- on some OMAP3 revisions, due to a hardware bug.
-
-config MTD_NAND_OMAP_BCH4
- bool "4 bits / 512 bytes"
- help
- Support correcting up to 4 bitflips per 512-byte block.
- This will use 7 bytes of spare area per 512 bytes of page data.
- Note that this mode does not work on some OMAP3 revisions, due to a
- hardware bug. Please check your OMAP datasheet before selecting this
- mode.
-
-endchoice
+ Some devices have built-in ELM hardware engine, which can be used to
+ locate and correct errors when using BCH ECC scheme. This enables the
+ driver support for same.
if MTD_NAND_OMAP_BCH
config BCH_CONST_M
diff --git a/drivers/mtd/nand/omap2.c b/drivers/mtd/nand/omap2.c
index fb96251..a783dae 100644
--- a/drivers/mtd/nand/omap2.c
+++ b/drivers/mtd/nand/omap2.c
@@ -27,6 +27,7 @@
#ifdef CONFIG_MTD_NAND_ECC_BCH
#include <linux/bch.h>
+#include <linux/mtd/nand_bch.h>
#endif
#ifdef CONFIG_MTD_NAND_OMAP_BCH
#include <linux/platform_data/elm.h>
@@ -144,7 +145,6 @@
#define BCH_ECC_SIZE1 0x20 /* ecc_size1 = 32 */
#define BADBLOCK_MARKER_LENGTH 2
-#define OMAP_ECC_BCH8_POLYNOMIAL 0x201b
#ifdef CONFIG_MTD_NAND_OMAP_BCH
static u_char bch8_vector[] = {0xf3, 0xdb, 0x14, 0x16, 0x8b, 0xd2, 0xbe, 0xcc,
@@ -188,7 +188,6 @@ struct omap_nand_info {
int buf_len;
struct gpmc_nand_regs reg;
/* fields specific for BCHx_HW ECC scheme */
- struct bch_control *bch;
bool is_elm_used;
struct device *elm_dev;
struct device_node *of_node;
@@ -1522,43 +1521,7 @@ static int omap_elm_correct_data(struct mtd_info *mtd, u_char *data,
return stat;
}
-#endif /* CONFIG_MTD_NAND_OMAP_BCH */
-#ifdef CONFIG_MTD_NAND_ECC_BCH
-/**
- * omap3_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 omap3_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 omap_nand_info *info = container_of(mtd, struct omap_nand_info,
- mtd);
-
- count = decode_bch(info->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);
- pr_debug("corrected bitflip %u\n", errloc[i]);
- }
- } else if (count < 0) {
- pr_err("ecc unrecoverable error\n");
- }
- return count;
-}
-#endif /* CONFIG_MTD_NAND_ECC_BCH */
-
-#ifdef CONFIG_MTD_NAND_OMAP_BCH
/**
* omap_write_page_bch - BCH ecc based write page function for entire page
* @mtd: mtd info structure
@@ -1675,28 +1638,6 @@ static int is_elm_present(struct omap_nand_info *info,
}
#endif /* CONFIG_MTD_NAND_ECC_BCH */
-#ifdef CONFIG_MTD_NAND_ECC_BCH
-/**
- * omap3_free_bch - Release BCH ecc resources
- * @mtd: MTD device structure
- */
-static void omap3_free_bch(struct mtd_info *mtd)
-{
- struct omap_nand_info *info = container_of(mtd, struct omap_nand_info,
- mtd);
- if (info->bch) {
- free_bch(info->bch);
- info->bch = NULL;
- }
-}
-
-#else
-
-static void omap3_free_bch(struct mtd_info *mtd)
-{
-}
-#endif /* CONFIG_MTD_NAND_ECC_BCH */
-
static int omap_nand_probe(struct platform_device *pdev)
{
struct omap_nand_info *info;
@@ -1731,10 +1672,10 @@ static int omap_nand_probe(struct platform_device *pdev)
mtd->owner = THIS_MODULE;
mtd->priv = &info->nand;
nand_chip = &info->nand;
+ nand_chip->ecc.priv = NULL;
info->pdev = pdev;
info->gpmc_cs = pdata->cs;
info->reg = pdata->reg;
- info->bch = NULL;
nand_chip->options |= NAND_SKIP_BBTSCAN | NAND_BUSWIDTH_AUTO;
info->of_node = pdata->of_node;
@@ -1927,7 +1868,7 @@ static int omap_nand_probe(struct platform_device *pdev)
nand_chip->ecc.bytes = 7;
nand_chip->ecc.strength = 4;
nand_chip->ecc.hwctl = omap3_enable_hwecc_bch;
- nand_chip->ecc.correct = omap3_correct_data_bch;
+ info->nand.ecc.correct = nand_bch_correct_data;
nand_chip->ecc.calculate = omap3_calculate_ecc_bch4;
/* define custom ECC layout */
ecclayout->eccbytes = nand_chip->ecc.bytes *
@@ -1937,10 +1878,11 @@ static int omap_nand_probe(struct platform_device *pdev)
ecclayout->oobfree->offset = ecclayout->eccpos[0] +
ecclayout->eccbytes;
/* software bch library is used for locating errors */
- info->bch = init_bch(nand_chip->ecc.bytes,
- nand_chip->ecc.strength,
- OMAP_ECC_BCH8_POLYNOMIAL);
- if (!info->bch) {
+ info->nand.ecc.priv = nand_bch_init(mtd,
+ info->nand.ecc.size,
+ info->nand.ecc.bytes,
+ &info->nand.ecc.layout);
+ if (!info->nand.ecc.priv) {
pr_err("nand: error: unable to use s/w BCH library\n");
err = -EINVAL;
}
@@ -1951,6 +1893,39 @@ static int omap_nand_probe(struct platform_device *pdev)
goto out_release_mem_region;
#endif
+ case OMAP_ECC_BCH4_CODE_HW:
+#ifdef CONFIG_MTD_NAND_OMAP_BCH
+ pr_info("nand: using OMAP_ECC_BCH4_CODE_HW ECC scheme\n");
+ info->nand.ecc.mode = NAND_ECC_HW;
+ info->nand.ecc.size = 512;
+ /* 14th bit is kept reserved for ROM-code compatibility */
+ info->nand.ecc.bytes = 7 + 1;
+ info->nand.ecc.strength = 4;
+ info->nand.ecc.hwctl = omap3_enable_hwecc_bch;
+ info->nand.ecc.correct = omap_elm_correct_data;
+ info->nand.ecc.calculate = omap3_calculate_ecc_bch;
+ info->nand.ecc.read_page = omap_read_page_bch;
+ info->nand.ecc.write_page = omap_write_page_bch;
+ /* This ECC scheme requires ELM H/W block */
+ if (is_elm_present(info, pdata->elm_of_node, BCH4_ECC) < 0) {
+ pr_err("nand: error: could not initialize ELM\n");
+ err = -ENODEV;
+ goto out_release_mem_region;
+ }
+ /* define ECC layout */
+ ecclayout->eccbytes = info->nand.ecc.bytes *
+ (mtd->writesize /
+ info->nand.ecc.size);
+ ecclayout->eccpos[0] = BADBLOCK_MARKER_LENGTH;
+ ecclayout->oobfree->offset = ecclayout->eccpos[0] +
+ ecclayout->eccbytes;
+ break;
+#else
+ pr_err("nand: error: CONFIG_MTD_NAND_OMAP_BCH not enabled\n");
+ err = -EINVAL;
+ goto out_release_mem_region;
+#endif
+
case OMAP_ECC_BCH8_CODE_HW_DETECTION_SW:
#ifdef CONFIG_MTD_NAND_ECC_BCH
pr_info("nand: using OMAP_ECC_BCH8_CODE_HW_DETECTION_SW\n");
@@ -1959,7 +1934,7 @@ static int omap_nand_probe(struct platform_device *pdev)
nand_chip->ecc.bytes = 13;
nand_chip->ecc.strength = 8;
nand_chip->ecc.hwctl = omap3_enable_hwecc_bch;
- nand_chip->ecc.correct = omap3_correct_data_bch;
+ info->nand.ecc.correct = nand_bch_correct_data;
nand_chip->ecc.calculate = omap3_calculate_ecc_bch8;
/* define custom ECC layout */
ecclayout->eccbytes = nand_chip->ecc.bytes *
@@ -1969,10 +1944,11 @@ static int omap_nand_probe(struct platform_device *pdev)
ecclayout->oobfree->offset = ecclayout->eccpos[0] +
ecclayout->eccbytes;
/* software bch library is used for locating errors */
- info->bch = init_bch(nand_chip->ecc.bytes,
- nand_chip->ecc.strength,
- OMAP_ECC_BCH8_POLYNOMIAL);
- if (!info->bch) {
+ info->nand.ecc.priv = nand_bch_init(mtd,
+ info->nand.ecc.size,
+ info->nand.ecc.bytes,
+ &info->nand.ecc.layout);
+ if (!info->nand.ecc.priv) {
pr_err("nand: error: unable to use s/w BCH library\n");
err = -EINVAL;
goto out_release_mem_region;
@@ -2023,7 +1999,6 @@ static int omap_nand_probe(struct platform_device *pdev)
}
/* populate remaining info for custom ecc layout */
- pr_info("%s: using custom ecc layout\n", DRIVER_NAME);
ecclayout->oobfree->length = mtd->oobsize - BADBLOCK_MARKER_LENGTH
- ecclayout->eccbytes;
if (!(nand_chip->options & NAND_BUSWIDTH_16))
@@ -2061,7 +2036,12 @@ out_release_mem_region:
free_irq(info->gpmc_irq_fifo, info);
release_mem_region(info->phys_base, info->mem_size);
out_free_info:
- omap3_free_bch(&info->mtd);
+#ifdef CONFIG_MTD_NAND_ECC_BCH
+ if (info->nand.ecc.priv) {
+ nand_bch_free(info->nand.ecc.priv);
+ info->nand.ecc.priv = NULL;
+ }
+#endif
kfree(info);
return err;
@@ -2072,8 +2052,12 @@ static int omap_nand_remove(struct platform_device *pdev)
struct mtd_info *mtd = platform_get_drvdata(pdev);
struct omap_nand_info *info = container_of(mtd, struct omap_nand_info,
mtd);
- omap3_free_bch(&info->mtd);
-
+#ifdef CONFIG_MTD_NAND_ECC_BCH
+ if (info->nand.ecc.priv) {
+ nand_bch_free(info->nand.ecc.priv);
+ info->nand.ecc.priv = NULL;
+ }
+#endif
if (info->dma)
dma_release_channel(info->dma);
--
1.8.1
--
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