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# SPDX-License-Identifier: GPL-2.0+
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#
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# (C) Copyright 2015 Mateusz Kulikowski <mateusz.kulikowski@gmail.com>
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Build & Run instructions:
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1) Install mkbootimg and dtbTool from
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git://codeaurora.org/quic/kernel/skales (15ece94f09 worked for me)
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2) Setup CROSS_COMPILE to aarch64 compiler
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3) make dragonboard410c_config
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4) make
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5) generate fake, empty ramdisk (can have 0 bytes)
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$ touch rd
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6) Generate qualcomm device tree table with dtbTool [1]
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$ dtbTool -o dt.img arch/arm/dts
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7) Generate Android boot image with mkbootimg [2]:
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$ mkbootimg --kernel=u-boot-dtb.bin --output=u-boot.img --dt=dt.img \
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--pagesize 2048 --base 0x80000000 --ramdisk=rd --cmdline=""
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8) Enter fastboot (reboot board with vol- button pressed)
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9) Boot it:
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$ fastboot boot u-boot.img
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or flash as kernel:
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$ fastboot flash boot u-boot.img
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$ fastboot reboot
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What is working:
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- UART
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- GPIO (SoC)
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- SD
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- eMMC
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- Reset
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- USB in EHCI mode (usb starts does switch device->host, usb stop does the opposite)
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- PMIC GPIOS (but not in generic subsystem)
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- PMIC "special" buttons (power, vol-)
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What is not working / known bugs:
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- SDHCI is slow (~2.5MiB/s for SD and eMMC)
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[1] To boot any kernel image, Little Kernel requires valid device tree for the
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platform it runs on. dtbTool creates device tree table that Little Kernel scans.
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Later on proper device tree is passed to next boot stage.
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Full device tree is not required to boot u-boot. Enough would be:
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/dts-v1/;
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/ {
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model = "Qualcomm Technologies, Inc. Dragonboard 410c";
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compatible = "qcom,dragonboard", "qcom,apq8016-sbc";
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qcom,msm-id = <0xce 0x0 0xf8 0x0 0xf9 0x0 0xfa 0x0 0xf7 0x0>;
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qcom,board-id = <0x10018 0x0>;
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#address-cells = <0x2>;
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#size-cells = <0x2>;
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chosen { };
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aliases { };
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memory {
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device_type = "memory";
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reg = <0 0x80000000 0 0x3da00000>;
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};
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};
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but for simplicity (and because size of image is not that critical) we use
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existing Qualcomm device trees.
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[2] Note that ramdisk is required, even if it is unused.
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