On Fri, Oct 04, 2013 at 08:49:44PM +0100, Pekon Gupta wrote:
> OMAP NAND driver support multiple ECC scheme, which can used in following
> different flavours, depending on in-build Hardware engines supported by SoC.
>
> +---------------------------------------+---------------+---------------+
> | ECC scheme |ECC calculation|Error detection|
> +---------------------------------------+---------------+---------------+
> |OMAP_ECC_HAM1_CODE_HW |H/W (GPMC) |S/W |
> +---------------------------------------+---------------+---------------+
> |OMAP_ECC_BCH8_CODE_HW_DETECTION_SW |H/W (GPMC) |S/W |
> |(requires CONFIG_MTD_NAND_ECC_BCH) | | |
> +---------------------------------------+---------------+---------------+
> |OMAP_ECC_BCH8_CODE_HW |H/W (GPMC) |H/W (ELM) |
> |(requires CONFIG_MTD_NAND_OMAP_BCH && | | |
> | ti,elm-id in DT) | | |
> +---------------------------------------+---------------+---------------+
> To optimize footprint of omap2-nand driver, selection of some ECC schemes
> also require enabling following Kconfigs, in addition to setting appropriate
> DT bindings
> - Kconfig:CONFIG_MTD_NAND_ECC_BCH error detection done in software
> - Kconfig:CONFIG_MTD_NAND_OMAP_BCH error detection done by h/w engine
>
> DT binding updates in this patch are:
> - ti,elm-id: replaces elm_id
> - ti,nand-ecc-opts: supported values ham1, bch4, and bch8
> selection of h/w or s/w implementation depends on ti,elm-id
>
> Signed-off-by: Pekon Gupta <pekon@xxxxxx>
> ---
> .../devicetree/bindings/mtd/gpmc-nand.txt | 8 +++-
> arch/arm/mach-omap2/gpmc.c | 47 ++++++++++++++++------
> include/linux/platform_data/mtd-nand-omap2.h | 14 +++++--
> 3 files changed, 52 insertions(+), 17 deletions(-)
>
> diff --git a/Documentation/devicetree/bindings/mtd/gpmc-nand.txt b/Documentation/devicetree/bindings/mtd/gpmc-nand.txt
> index 25ee232..7785666 100644
> --- a/Documentation/devicetree/bindings/mtd/gpmc-nand.txt
> +++ b/Documentation/devicetree/bindings/mtd/gpmc-nand.txt
> @@ -36,8 +36,12 @@ Optional properties:
> "prefetch-dma" Prefetch enabled sDMA mode
> "prefetch-irq" Prefetch enabled irq mode
>
> - - elm_id: Specifies elm device node. This is required to support BCH
> - error correction using ELM module.
> + - elm_id: <deprecated> use "ti,elm-id" instead
> + - ti,elm-id: Specifies pHandle of the ELM devicetree node.
s/pHandle/phandle/
> + ELM is an on-chip hardware engine on TI SoC which is used for
> + locating ECC errors for BCHx algorithms. SoC devices which have
> + ELM hardware engines should specify this device node in .dtsi
> + Using ELM for ECC error correction frees some CPU cycles.
>
> For inline partiton table parsing (optional):
>
> diff --git a/arch/arm/mach-omap2/gpmc.c b/arch/arm/mach-omap2/gpmc.c
> index 1c45b72..5a607fa 100644
> --- a/arch/arm/mach-omap2/gpmc.c
> +++ b/arch/arm/mach-omap2/gpmc.c
> @@ -1341,12 +1341,6 @@ static void __maybe_unused gpmc_read_timings_dt(struct device_node *np,
>
> #ifdef CONFIG_MTD_NAND
>
> -static const char * const nand_ecc_opts[] = {
> - [OMAP_ECC_HAM1_CODE_HW] = "ham1",
> - [OMAP_ECC_BCH4_CODE_HW] = "bch4",
> - [OMAP_ECC_BCH8_CODE_HW] = "bch8",
> -};
> -
> static const char * const nand_xfer_types[] = {
> [NAND_OMAP_PREFETCH_POLLED] = "prefetch-polled",
> [NAND_OMAP_POLLED] = "polled",
> @@ -1361,6 +1355,8 @@ static int gpmc_probe_nand_child(struct platform_device *pdev,
> const char *s;
> struct gpmc_timings gpmc_t;
> struct omap_nand_platform_data *gpmc_nand_data;
> + const __be32 *phandle;
I don't think you need this. With of_parse_phandle you should never need
to see the raw phandle value.
> + int lenp;
>
> if (of_property_read_u32(child, "reg", &val) < 0) {
> dev_err(&pdev->dev, "%s has no 'reg' property\n",
> @@ -1376,12 +1372,39 @@ static int gpmc_probe_nand_child(struct platform_device *pdev,
> gpmc_nand_data->cs = val;
> gpmc_nand_data->of_node = child;
>
> - if (!of_property_read_string(child, "ti,nand-ecc-opt", &s))
> - for (val = 0; val < ARRAY_SIZE(nand_ecc_opts); val++)
> - if (!strcasecmp(s, nand_ecc_opts[val])) {
> - gpmc_nand_data->ecc_opt = val;
> - break;
> - }
> + /* Detect availability of ELM module */
> + phandle = of_get_property(child, "ti,elm-id", &lenp);
> + if ((phandle == NULL) || (lenp != sizeof(void *))) {
> + pr_warn("%s: ti,elm-id property not found\n", __func__);
> + gpmc_nand_data->elm_of_node = NULL;
> + } else {
> + gpmc_nand_data->elm_of_node =
> + of_find_node_by_phandle(be32_to_cpup(phandle));
> + }
Use of_parse_handle rather than open-coding it:
gpmc_nand_data->elm_of_node =
of_parse_phandle(child, "ti,elm-id", 0);
Was "elm_id" ever handled previously? I don't see any code handling it
being remove or modified.
Thanks,
Mark.
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