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diff --git a/doc/board/samsung/e850-96.rst b/doc/board/samsung/e850-96.rst new file mode 100644 index 00000000000..0cb95473e53 --- /dev/null +++ b/doc/board/samsung/e850-96.rst @@ -0,0 +1,87 @@ +.. SPDX-License-Identifier: GPL-2.0+ +.. sectionauthor:: Sam Protsenko <semen.protsenko@linaro.org> + +WinLink E850-96 board +===================== + +Overview +-------- + +WinLink's E850-96 board [1]_ is based on Samsung Exynos850 SoC and follows +96Boards Consumer Edition specification [2]_. That makes it possible to use +96Boards mezzanine boards [3]_ along with it. It's an open-hardware board and +the hardware design files [4]_ were published, along with the supported +software [5]_ and related documentation. + +U-Boot can be used on E850-96 instead of the original Samsung LittleKernel based +bootloader [6]_. Because FWBL1 [7]_ doesn't verify bootloader's signature, there +is no need to sign a U-Boot binary. That means U-Boot binary can be flashed into +``bootloader`` partition (instead of LittleKernel bootloader) and it will just +work. + +Because BL2 bootloader already sets up DRAM and runs the final bootloader +(U-Boot) from DRAM, there is no need in U-Boot SPL. It's enough to have only +U-Boot proper (``u-boot.bin``). + +Boot Flow +--------- + +The boot path for Exynos850 is shown on the figure below. + +.. image:: img/exynos850-boot-architecture.svg + :alt: Exynos850 SoC boot flow + +Legend: + +* ``BL0``: Boot ROM code +* ``BL1``: Software part of Boot ROM +* ``EPBL``: Exynos Primary Boot Loader +* ``BL2``: Initializes CMU and DRAM and runs the final bootloader +* ``Bootloader``: Final bootloader (e.g. U-Boot); also called BL33 in terms of + ARM boot flow +* ``EL3_MON``: EL3 monitor (trusted firmware, handles SMC calls); also called + BL31 in terms of ARM boot flow +* ``LDFW``: Loadable Firmware + +Build Procedure +--------------- + +.. warning:: + At the moment both eMMC and USB features are not enabled in U-Boot. Flashing + U-Boot binary **WILL** effectively brick your board. The ``dltool`` [8]_ can + be used then to perform USB boot and flash LittleKernel bootloader binary [7]_ + to unbrick and revive the board. Flashing U-Boot binary might be helpful for + developers or anybody who want to check current state of U-Boot enablement on + E850-96 (which is mostly serial console and related blocks). + +Build U-Boot binary from source code (using AArch64 baremetal GCC toolchain): + +.. prompt:: bash $ + + export PATH=<toolchain path>/bin:$PATH + export CROSS_COMPILE=<toolchain prefix> + make e850-96_defconfig + make + +Boot E850-96 board into fastboot mode as described in board software doc [9]_, +and flash U-Boot binary into ``bootloader`` eMMC partition: + +.. prompt:: bash $ + + fastboot flash bootloader u-boot.bin + fastboot reboot + +U-Boot will boot up to the shell. + +References +---------- + +.. [1] https://www.96boards.org/product/e850-96b/ +.. [2] https://www.96boards.org/products/ce/ +.. [3] https://www.96boards.org/products/mezzanine/ +.. [4] https://www.96boards.org/documentation/consumer/e850-96b/hardware-docs/ +.. [5] https://gitlab.com/Linaro/96boards/e850-96/ +.. [6] https://gitlab.com/Linaro/96boards/e850-96/lk +.. [7] https://gitlab.com/Linaro/96boards/e850-96/images +.. [8] https://gitlab.com/Linaro/96boards/e850-96/tools/dltool +.. [9] https://gitlab.com/Linaro/96boards/e850-96/doc |