[U-Boot] [PATCH v2 12/14] scripts: sunxi: Build an raw SPL image

[Boris Brezillon <boris.brezillon@free-electrons.com>]

On Tue, 22 Nov 2016 13:38:42 +0100
Maxime Ripard <maxime.ripard@free-electrons.com> wrote:

> Introduce a new sunxi-spl-with-ecc.bin image with already the right header,
> ECC, randomizer and padding for the BROM to be able to read it.
> 
> It needs to be flashed using a raw access to the NAND so that the
> controller doesn't change a thing to it, since we already have all the
> right parameters.
> 
> Signed-off-by: Maxime Ripard <maxime.ripard@free-electrons.com>
> Acked-by: Boris Brezillon <boris.brezillon@free-electrons.com>
> ---
>  Makefile                |  3 ++-
>  board/sunxi/README.nand | 54 ++++++++++++++++++++++++++++++++++++++++++-
>  scripts/Makefile.spl    | 15 ++++++++++++-
>  3 files changed, 72 insertions(+), 0 deletions(-)
>  create mode 100644 board/sunxi/README.nand
> 
> diff --git a/Makefile b/Makefile
> index 37cbcb28f75e..12a248e297b5 100644
> --- a/Makefile
> +++ b/Makefile
> @@ -1345,6 +1345,9 @@ spl/u-boot-spl: tools prepare \
>  spl/sunxi-spl.bin: spl/u-boot-spl
>  	@:
>  
> +spl/sunxi-spl-with-ecc.bin: spl/sunxi-spl.bin
> +	@:
> +
>  spl/u-boot-spl.sfp: spl/u-boot-spl
>  	@:
>  
> diff --git a/board/sunxi/README.nand b/board/sunxi/README.nand
> new file mode 100644
> index 000000000000..a5d4ff0e90a3
> --- /dev/null
> +++ b/board/sunxi/README.nand
> @@ -0,0 +1,54 @@
> +Allwinner NAND flashing
> +=======================
> +
> +A lot of Allwinner devices, especially the older ones (pre-H3 era),
> +comes with a NAND. NANDs storages are a pretty weak choice when it
> +comes to the reliability, and it comes with a number of flaws like
> +read and write disturbs, data retention issues, bloks becoming
> +unusable, etc.
> +
> +In order to mitigate that, various strategies have been found to be
> +able to recover from those issues like ECC, hardware randomization,
> +and of course, redundancy for the critical parts.
> +
> +This is obviously something that we will take into account when
> +creating our images. However, the BROM will use a quite weird pattern
> +when accessing the NAND, and will access only at most 4kB per page,
> +which means that we also have to split that binary accross several
> +pages.
> +
> +In order to accomodate that, we create a tool that will generate an
> +SPL image that is ready to be programmed directly embedding the ECCs,
> +randomized, and with the necessary bits needed to reduce the number of
> +bitflips. The U-Boot build system, when configured for the NAND will
> +also generate the image sunxi-spl-with-ecc.bin that will have been
> +generated by that tool.
> +
> +In order to flash your U-Boot image onto a board, assuming that the
> +board is in FEL mode, you'll need the sunxi-tools that you can find at
> +this repository: https://github.com/linux-sunxi/sunxi-tools
> +
> +Then, you'll need to first load an SPL to initialise the RAM:
> +sunxi-fel spl spl/sunxi-spl.bin
> +
> +Load the binaries we'll flash into RAM:
> +sunxi-fel write 0x4a000000 u-boot-dtb.bin
> +sunxi-fel write 0x43000000 spl/sunxi-spl-with-ecc.bin
> +
> +And execute U-Boot
> +sunxi-fel exe 0x4a000000
> +
> +On your board, you'll now have all the needed binaries into RAM, so
> +you only need to erase the NAND...
> +
> +nand erase.chip
> +
> +Then write the SPL and its backup:
> +
> +nand write.raw.noverify 0x43000000 0 40
> +nand write.raw.noverify 0x43000000 0x400000 40
> +
> +And finally write the U-Boot binary:
> +nand write 0x4a000000 0x800000 0xc0000
> +
> +You can now reboot and enjoy your NAND.
> \ No newline at end of file
> diff --git a/scripts/Makefile.spl b/scripts/Makefile.spl
> index e0b0117dc9b6..6a381f26d21a 100644
> --- a/scripts/Makefile.spl
> +++ b/scripts/Makefile.spl
> @@ -168,6 +168,10 @@ endif
>  
>  ifdef CONFIG_ARCH_SUNXI
>  ALL-y	+= $(obj)/sunxi-spl.bin
> +
> +ifdef CONFIG_NAND_SUNXI
> +ALL-y	+= $(obj)/sunxi-spl-with-ecc.bin
> +endif
>  endif
>  
>  ifeq ($(CONFIG_SYS_SOC),"at91")
> @@ -276,6 +280,17 @@ cmd_mksunxiboot = $(objtree)/tools/mksunxiboot $< $@
>  $(obj)/sunxi-spl.bin: $(obj)/$(SPL_BIN).bin FORCE
>  	$(call if_changed,mksunxiboot)
>  
> +quiet_cmd_sunxi_spl_image_builder = SUNXI_SPL_IMAGE_BUILDER $@
> +cmd_sunxi_spl_image_builder = $(objtree)/tools/sunxi-spl-image-builder \
> +				-c $(CONFIG_NAND_SUNXI_SPL_ECC_STRENGTH)/$(CONFIG_NAND_SUNXI_SPL_ECC_SIZE) \
> +				-p $(CONFIG_SYS_NAND_PAGE_SIZE) \
> +				-o $(CONFIG_SYS_NAND_OOBSIZE) \
> +				-u $(CONFIG_NAND_SUNXI_SPL_USABLE_PAGE_SIZE) \
> +				-e $(CONFIG_SYS_NAND_BLOCK_SIZE) \
> +				-s -b $< $@

Maybe you should define default values for SYS_NAND_PAGE_SIZE,
SYS_NAND_OOBSIZE and SYS_NAND_BLOCK_SIZE in case the SYS_EXTRA_OPTIONS
option does not contain these definitions in order to avoid build
failures.

> +$(obj)/sunxi-spl-with-ecc.bin: $(obj)/sunxi-spl.bin
> +	$(call if_changed,sunxi_spl_image_builder)
> +
>  # Rule to link u-boot-spl
>  # May be overridden by arch/$(ARCH)/config.mk
>  quiet_cmd_u-boot-spl ?= LD      $@