u-boot-brain

History

Harald Seiler 35b65dd8ef reset: Remove addr parameter from reset_cpu() Historically, the reset_cpu() function had an `addr` parameter which was meant to pass in an address of the reset vector location, where the CPU should reset to. This feature is no longer used anywhere in U-Boot as all reset_cpu() implementations now ignore the passed value. Generic code has been added which always calls reset_cpu() with `0` which means this feature can no longer be used easily anyway. Over time, many implementations seem to have "misunderstood" the existence of this parameter as a way to customize/parameterize the reset (e.g. COLD vs WARM resets). As this is not properly supported, the code will almost always not do what it is intended to (because all call-sites just call reset_cpu() with 0). To avoid confusion and to clean up the codebase from unused left-overs of the past, remove the `addr` parameter entirely. Code which intends to support different kinds of resets should be rewritten as a sysreset driver instead. This transformation was done with the following coccinelle patch: @@ expression argvalue; @@ - reset_cpu(argvalue) + reset_cpu() @@ identifier argname; type argtype; @@ - reset_cpu(argtype argname) + reset_cpu(void) { ... } Signed-off-by: Harald Seiler <hws@denx.de> Reviewed-by: Simon Glass <sjg@chromium.org>		2021-03-02 14:03:02 -05:00
..
Kconfig	board: Add Qualcomm Dragonboard 410C support	2016-04-01 17:18:27 -04:00
MAINTAINERS	MAINTAINERS: change Ramon Fried email address	2019-06-14 10:09:15 -04:00
Makefile	SPDX: Convert all of our single license tags to Linux Kernel style	2018-05-07 09:34:12 -04:00
dragonboard410c.c	reset: Remove addr parameter from reset_cpu()	2021-03-02 14:03:02 -05:00
head.S	SPDX: Convert all of our single license tags to Linux Kernel style	2018-05-07 09:34:12 -04:00
lowlevel_init.S	SPDX: Convert all of our single license tags to Linux Kernel style	2018-05-07 09:34:12 -04:00
readme.txt	SPDX: Convert all of our single license tags to Linux Kernel style	2018-05-07 09:34:12 -04:00
u-boot.lds	efi_loader: Rename sections to allow for implicit data	2018-07-25 14:57:44 +02:00

readme.txt

# SPDX-License-Identifier: GPL-2.0+
#
# (C) Copyright 2015 Mateusz Kulikowski <mateusz.kulikowski@gmail.com>

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.