[U-Boot] [PATCH v3 5/6] omap_gpmc: add support for hw assisted BCH8

[Thomas Weber <thomas.weber.linux@googlemail.com>]

Hello Andreas,

On 04/03/2013 04:50 PM, Andreas Bie?mann wrote:
> 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
>
> since v2:
>  * fix all checkpatch warnings
>  * add more comments
>  * add NAND section in README.omap3
>
>  doc/README.omap3             |   19 +++
>  drivers/mtd/nand/omap_gpmc.c |  367 +++++++++++++++++++++++++++++++-----------
>  lib/Makefile                 |    2 +-
>  3 files changed, 296 insertions(+), 92 deletions(-)
>
> diff --git a/doc/README.omap3 b/doc/README.omap3
> index 0a37de0..56aca8e 100644
> --- a/doc/README.omap3
> +++ b/doc/README.omap3
> @@ -145,6 +145,25 @@ int omap3_dma_wait_for_transfer(uint32_t chan)
>  int omap3_dma_get_revision(uint32_t *minor, uint32_t *major)
>  	Read silicon Revision of the DMA module
>  
> +NAND
> +====
> +
> +Ther eare some OMAP3 devices out ther with NAND attached. Due to the fact that
    ther -> there
> +OMAP3 ROM code can only handle 1-bit hamming ECC for accessing first page
> +(place where SPL lives) we require this setup for u-boot at least when reading
> +the second progam within SPL.  A lot of newer NAND chips however require more
> +than 1-bit ECC for the pages, some can live with 1-bit for the first page. To
> +handle this we can switch to another ECC algorithm after reading the payload
> +within SPL.
> +
> +BCH8
> +----
> +
> +To enable hardware assisted BCH8 (8-bit BCH [Bose, Chaudhuri, Hocquenghem]) on
> +OMAP3 devices we can use the BCH library in lib/bch.c. To do so add CONFIG_BCH
> +to enable the library and CONFIG_NAND_OMAP_BCH8 to your board config.
> +The NAND OOB layout is the same as in linux kernel, if the linux kernel BCH8
> +implementation for OMAP3 works for you so the u-boot version should also.
>  
>  Acknowledgements
>  ================
>
Thomas