forked from OERV-BSP/u-boot
f83f2397a1
Now that USB is enabled on the E850-96 board, DFU and fastboot tools are functional and can be used to flash images to eMMC. Update the E850-96 documentation accordingly and describe flashing to User Data Area and Boot HW Partition of eMMC using fastboot and DFU tools. Signed-off-by: Sam Protsenko <semen.protsenko@linaro.org> Signed-off-by: Minkyu Kang <mk7.kang@samsung.com>
152 lines
4.6 KiB
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152 lines
4.6 KiB
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.. SPDX-License-Identifier: GPL-2.0+
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.. sectionauthor:: Sam Protsenko <semen.protsenko@linaro.org>
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WinLink E850-96 board
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=====================
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Overview
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--------
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WinLink's E850-96 board [1]_ is based on Samsung Exynos850 SoC and follows
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96Boards Consumer Edition specification [2]_. That makes it possible to use
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96Boards mezzanine boards [3]_ along with it. It's an open-hardware board and
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the hardware design files [4]_ were published, along with the supported
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software [5]_ and related documentation.
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U-Boot can be used on E850-96 instead of the original Samsung LittleKernel based
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bootloader [6]_. Because FWBL1 [7]_ doesn't verify bootloader's signature, there
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is no need to sign a U-Boot binary. That means U-Boot binary can be flashed into
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``bootloader`` partition (instead of LittleKernel bootloader) and it will just
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work.
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Because BL2 bootloader already sets up DRAM and runs the final bootloader
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(U-Boot) from DRAM, there is no need in U-Boot SPL. It's enough to have only
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U-Boot proper (``u-boot.bin``).
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Boot Flow
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---------
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The boot path for Exynos850 is shown on the figure below.
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.. image:: img/exynos850-boot-architecture.svg
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:alt: Exynos850 SoC boot flow
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Legend:
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* ``BL0``: Boot ROM code
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* ``BL1``: Software part of Boot ROM
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* ``EPBL``: Exynos Primary Boot Loader
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* ``BL2``: Initializes CMU and DRAM and runs the final bootloader
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* ``Bootloader``: Final bootloader (e.g. U-Boot); also called BL33 in terms of
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ARM boot flow
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* ``EL3_MON``: EL3 monitor (trusted firmware, handles SMC calls); also called
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BL31 in terms of ARM boot flow
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* ``LDFW``: Loadable Firmware
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Unbricking Note
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---------------
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In case the board is bricked for some reason, the ``dltool`` [8]_ can be used to
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unbrick and revive it. This tool performs USB boot, and uploads the LittleKernel
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bootloader over USB, which is then being executed on the board. The loaded
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bootloader further enters fastboot mode, so that the user can flash the
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functional bootloader binary (U-Boot or LittleKernel [7]_) to eMMC using
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``fastboot`` tool. Please read the ``dltool`` README file for more details about
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the procedure.
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Build Procedure
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---------------
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Build U-Boot binary from source code (using AArch64 baremetal GCC toolchain):
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.. prompt:: bash $
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export PATH=<toolchain path>/bin:$PATH
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export CROSS_COMPILE=<toolchain prefix>
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make e850-96_defconfig
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make
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The original E850-96 board is shipped with LittleKernel-based bootloader flashed
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in eMMC. To replace it with U-Boot, boot into fastboot mode (as described in
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the board software documentation [9]_), and flash U-Boot binary:
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.. prompt:: bash $
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fastboot flash bootloader u-boot.bin
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fastboot reboot
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U-Boot will boot up to the shell.
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Flashing
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--------
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User area of eMMC contains GPT partition table (either Linux or Android). Boot
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Partition A (``mmc0boot0``) contains all firmware/bootloaders. Boot Partition
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B (``mmc0boot1``) contains U-Boot environment.
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First make sure to format eMMC accordingly. Prepare the initial environment:
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.. prompt:: bash =>
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env default -f -a
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env save
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For Linux, just format eMMC using default ``$partitions`` definitions:
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.. prompt:: bash =>
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gpt write mmc 0 $partitions
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For Android, use ``$partitions_android`` instead:
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.. prompt:: bash =>
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setenv partitions_linux $partitions
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setenv partitions $partitions_android
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env save
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gpt write mmc 0 $partitions
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In case of Linux, there are two partitions available: ``esp`` (EFI System
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Partition) and ``rootfs``. It is recommended to use fastboot to flash images to
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those partitions. Enter fastboot mode on your device:
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.. prompt:: bash =>
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fastboot usb 0
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And then flash the images:
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.. prompt:: bash $
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fastboot flash esp esp.img
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fastboot flash rootfs rootfs.img
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To update the firmware, it's easier to use DFU. Enter DFU mode on the board:
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.. prompt:: bash =>
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dfu 0 mmc 0
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To update U-Boot:
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.. prompt:: bash $
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dfu-util -D u-boot.bin -a bootloader
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It's also possible to use fastboot to flash the whole ``mmc0boot0`` HW
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partition, but it's not so straightforward, as one have to prepare the image for
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the whole ``boot0`` partition containing all firmware binaries first.
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References
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----------
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.. [1] https://www.96boards.org/product/e850-96b/
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.. [2] https://www.96boards.org/products/ce/
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.. [3] https://www.96boards.org/products/mezzanine/
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.. [4] https://www.96boards.org/documentation/consumer/e850-96b/hardware-docs/
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.. [5] https://gitlab.com/Linaro/96boards/e850-96/
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.. [6] https://gitlab.com/Linaro/96boards/e850-96/lk
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.. [7] https://gitlab.com/Linaro/96boards/e850-96/images
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.. [8] https://gitlab.com/Linaro/96boards/e850-96/tools/dltool
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.. [9] https://gitlab.com/Linaro/96boards/e850-96/doc
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