On Fri, Oct 11, 2013 at 07:06:41PM +0530, Pekon Gupta wrote:
> 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>
Reviewed-by: Felipe Balbi <balbi@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
>
--
balbi
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