#
|
# (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.
|
