[PATCH v5 1/4] ARM: OMAP2+: cleaned-up DT support of various ECC schemes
Brian Norris
computersforpeace at gmail.com
Tue Aug 20 21:26:10 EDT 2013
Including the correct device-tree list.
On Sun, Jul 14, 2013 at 02:24:48AM +0530, Pekon Gupta wrote:
> ECC scheme on NAND devices can be implemented in multiple ways.Some using
> Software algorithm, while others using in-build Hardware engines.
> omap2-nand driver currently supports following flavours of ECC schemes,
> selectable via DTB.
>
> +---------------------------------------+---------------+---------------+
> | ECC scheme |ECC calculation|Error detection|
> +---------------------------------------+---------------+---------------+
> |OMAP_ECC_HAMMING_CODE_DEFAULT |S/W |S/W |
> |OMAP_ECC_HAMMING_CODE_HW |H/W (GPMC) |S/W |
> |OMAP_ECC_HAMMING_CODE_HW_ROMCODE |H/W (GPMC) |S/W |
> +---------------------------------------+---------------+---------------+
> |(requires CONFIG_MTD_NAND_ECC_BCH) | | |
> |OMAP_ECC_BCH8_CODE_HW_DETECTION_SW |H/W (GPMC) |S/W |
> +---------------------------------------+---------------+---------------+
> |(requires CONFIG_MTD_NAND_OMAP_BCH) | | |
> |OMAP_ECC_BCH8_CODE_HW |H/W (GPMC) |H/W (ELM) |
> +---------------------------------------+---------------+---------------+
>
> Selection of some ECC schemes also require enabling following Kconfig options.
> This was done to optimize footprint of omap2-nand driver.
> -Kconfig:CONFIG_MTD_NAND_ECC_BCH enables S/W based BCH ECC algorithm
> -Kconfig:CONFIG_MTD_NAND_OMAP_BCH enables H/W based BCH ECC algorithm
>
> Signed-off-by: Pekon Gupta <pekon at ti.com>
> ---
> .../devicetree/bindings/mtd/gpmc-nand.txt | 45 ++++++++++++++++------
> arch/arm/mach-omap2/gpmc.c | 14 ++++---
> include/linux/platform_data/mtd-nand-omap2.h | 22 +++++++----
> 3 files changed, 57 insertions(+), 24 deletions(-)
>
> diff --git a/Documentation/devicetree/bindings/mtd/gpmc-nand.txt b/Documentation/devicetree/bindings/mtd/gpmc-nand.txt
> index df338cb..c6551b6 100644
> --- a/Documentation/devicetree/bindings/mtd/gpmc-nand.txt
> +++ b/Documentation/devicetree/bindings/mtd/gpmc-nand.txt
> @@ -17,17 +17,42 @@ Required properties:
>
> Optional properties:
>
> - - nand-bus-width: Set this numeric value to 16 if the hardware
> - is wired that way. If not specified, a bus
> - width of 8 is assumed.
> + - nand-bus-width: Determines data-width of the connected device
> + x16 = "16"
> + x8 = "8" (default)
>
> - - ti,nand-ecc-opt: A string setting the ECC layout to use. One of:
>
> - "sw" Software method (default)
> - "hw" Hardware method
> - "hw-romcode" gpmc hamming mode method & romcode layout
> - "bch4" 4-bit BCH ecc code
> - "bch8" 8-bit BCH ecc code
> + - ti,nand-ecc-opt: Determines the ECC scheme used by driver.
> + It can be any of the following strings:
> +
> + "hamming_code_sw" 1-bit Hamming ECC
> + - ECC calculation in software
> + - Error detection in software
> +
> + "hamming_code_hw" 1-bit Hamming ECC
> + - ECC calculation in hardware
> + - Error detection in software
> +
> + "hamming_code_hw_romcode" 1-bit Hamming ECC
> + - ECC calculation in hardware
> + - Error detection in software
> + - ECC layout compatible to ROM code
> +
> + "bch8_hw_code_detection_sw" 8-bit BCH ECC
> + - ECC calculation in hardware
> + - Error detection in software
> + - depends on CONFIG_MTD_NAND_ECC_BCH
> +
> + "bch8_code_hw" 8-bit BCH ECC
> + - ECC calculation in hardware
> + - Error detection in hardware
> + - depends on CONFIG_MTD_NAND_OMAP_BCH
> + - requires <elm_id> to be specified
I'm pretty sure this is an ABI breakage, which is now considered
unacceptable. AFAIK, you can support new ECC types (or new aliases for
old ones), but you can't remove/rename old ones.
> +
> +
> + - elm_id: Specifies elm device node. This is required to
> + support some BCH ECC schemes mentioned above.
> +
>
> - ti,nand-xfer-type: A string setting the data transfer type. One of:
>
> @@ -36,8 +61,6 @@ 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.
>
> For inline partiton table parsing (optional):
>
> diff --git a/arch/arm/mach-omap2/gpmc.c b/arch/arm/mach-omap2/gpmc.c
> index 1c7969e..e19de21 100644
> --- a/arch/arm/mach-omap2/gpmc.c
> +++ b/arch/arm/mach-omap2/gpmc.c
> @@ -1342,11 +1342,13 @@ 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_HAMMING_CODE_DEFAULT] = "sw",
> - [OMAP_ECC_HAMMING_CODE_HW] = "hw",
> - [OMAP_ECC_HAMMING_CODE_HW_ROMCODE] = "hw-romcode",
> - [OMAP_ECC_BCH4_CODE_HW] = "bch4",
> - [OMAP_ECC_BCH8_CODE_HW] = "bch8",
> + [OMAP_ECC_HAMMING_CODE_DEFAULT] = "hamming_code_sw",
> + [OMAP_ECC_HAMMING_CODE_HW] = "hamming_code_hw",
> + [OMAP_ECC_HAMMING_CODE_HW_ROMCODE] = "hamming_code_hw_romcode",
> + [OMAP_ECC_BCH4_CODE_HW] = "bch4_code_hw",
> + [OMAP_ECC_BCH4_CODE_HW_DETECTION_SW] = "bch4_code_hw_detection_sw",
> + [OMAP_ECC_BCH8_CODE_HW] = "bch8_code_hw",
> + [OMAP_ECC_BCH8_CODE_HW_DETECTION_SW] = "bch8_code_hw_detection_sw"
> };
>
> static const char * const nand_xfer_types[] = {
> @@ -1380,7 +1382,7 @@ static int gpmc_probe_nand_child(struct platform_device *pdev,
>
> 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])) {
> + if (!strcmp(s, nand_ecc_opts[val])) {
> gpmc_nand_data->ecc_opt = val;
> break;
> }
> diff --git a/include/linux/platform_data/mtd-nand-omap2.h b/include/linux/platform_data/mtd-nand-omap2.h
> index 6bf9ef4..ce74576 100644
> --- a/include/linux/platform_data/mtd-nand-omap2.h
> +++ b/include/linux/platform_data/mtd-nand-omap2.h
> @@ -23,13 +23,21 @@ enum nand_io {
> };
>
> enum omap_ecc {
> - /* 1-bit ecc: stored at end of spare area */
> - OMAP_ECC_HAMMING_CODE_DEFAULT = 0, /* Default, s/w method */
> - OMAP_ECC_HAMMING_CODE_HW, /* gpmc to detect the error */
> - /* 1-bit ecc: stored at beginning of spare area as romcode */
> - OMAP_ECC_HAMMING_CODE_HW_ROMCODE, /* gpmc method & romcode layout */
> - OMAP_ECC_BCH4_CODE_HW, /* 4-bit BCH ecc code */
> - OMAP_ECC_BCH8_CODE_HW, /* 8-bit BCH ecc code */
> + /* 1-bit ECC calculation by Software, Error detection by Software */
> + OMAP_ECC_HAMMING_CODE_DEFAULT = 0,
> + /* 1-bit ECC calculation by GPMC, Error detection by Software */
> + OMAP_ECC_HAMMING_CODE_HW,
> + /* 1-bit ECC calculation by GPMC, Error detection by Software */
> + /* ECC layout compatible to legacy ROMCODE. */
> + OMAP_ECC_HAMMING_CODE_HW_ROMCODE,
> + /* 4-bit ECC calculation by GPMC, Error detection by ELM */
> + OMAP_ECC_BCH4_CODE_HW,
> + /* 4-bit ECC calculation by GPMC, Error detection by Software */
> + OMAP_ECC_BCH4_CODE_HW_DETECTION_SW,
> + /* 8-bit ECC calculation by GPMC, Error detection by ELM */
> + OMAP_ECC_BCH8_CODE_HW,
> + /* 8-bit ECC calculation by GPMC, Error detection by Software */
> + OMAP_ECC_BCH8_CODE_HW_DETECTION_SW
> };
>
> struct gpmc_nand_regs {
Brian
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