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