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> Reviewed-by: Heiko Schocher <hs@denx.de>master
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Allwinner NAND flashing |
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A lot of Allwinner devices, especially the older ones (pre-H3 era), |
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comes with a NAND. NANDs storages are a pretty weak choice when it |
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comes to the reliability, and it comes with a number of flaws like |
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read and write disturbs, data retention issues, bloks becoming |
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unusable, etc. |
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In order to mitigate that, various strategies have been found to be |
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able to recover from those issues like ECC, hardware randomization, |
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and of course, redundancy for the critical parts. |
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This is obviously something that we will take into account when |
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creating our images. However, the BROM will use a quite weird pattern |
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when accessing the NAND, and will access only at most 4kB per page, |
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which means that we also have to split that binary accross several |
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pages. |
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In order to accomodate that, we create a tool that will generate an |
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SPL image that is ready to be programmed directly embedding the ECCs, |
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randomized, and with the necessary bits needed to reduce the number of |
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bitflips. The U-Boot build system, when configured for the NAND will |
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also generate the image sunxi-spl-with-ecc.bin that will have been |
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generated by that tool. |
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In order to flash your U-Boot image onto a board, assuming that the |
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board is in FEL mode, you'll need the sunxi-tools that you can find at |
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this repository: https://github.com/linux-sunxi/sunxi-tools |
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Then, you'll need to first load an SPL to initialise the RAM: |
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sunxi-fel spl spl/sunxi-spl.bin |
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Load the binaries we'll flash into RAM: |
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sunxi-fel write 0x4a000000 u-boot-dtb.bin |
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sunxi-fel write 0x43000000 spl/sunxi-spl-with-ecc.bin |
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And execute U-Boot |
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sunxi-fel exe 0x4a000000 |
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On your board, you'll now have all the needed binaries into RAM, so |
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you only need to erase the NAND... |
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nand erase.chip |
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Then write the SPL and its backup: |
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nand write.raw.noverify 0x43000000 0 40 |
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nand write.raw.noverify 0x43000000 0x400000 40 |
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And finally write the U-Boot binary: |
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nand write 0x4a000000 0x800000 0xc0000 |
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You can now reboot and enjoy your NAND. |
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