mirror of
https://github.com/AsahiLinux/u-boot
synced 2024-11-08 22:24:32 +00:00
894c3ad27f
Add support for loading U-Boot on the Broadcom 7445 SoC. This port assumes Broadcom's BOLT bootloader is acting as the second stage bootloader, and U-Boot is acting as the third stage bootloader, loaded as an ELF program by BOLT. Signed-off-by: Thomas Fitzsimmons <fitzsim@fitzsim.org> Cc: Stefan Roese <sr@denx.de> Cc: Tom Rini <trini@konsulko.com> Cc: Florian Fainelli <f.fainelli@gmail.com>
150 lines
3.6 KiB
Text
150 lines
3.6 KiB
Text
Summary
|
|
=======
|
|
|
|
This document describes how to use U-Boot on the Broadcom 7445 SoC, as
|
|
a third stage bootloader loaded by Broadcom's BOLT bootloader.
|
|
|
|
BOLT loads U-Boot as a generic ELF binary. Some U-Boot features such
|
|
as networking are not yet available but other important features are,
|
|
including:
|
|
|
|
- ext4 file system traversal
|
|
|
|
- support for loading FIT images
|
|
|
|
- advanced scripting
|
|
|
|
- support for FIT-provided DTBs instead of relying on the
|
|
BOLT-provided DTB
|
|
|
|
A customized version of this port has been used in production. The
|
|
same approach may work on other BCM7xxx boards, with some
|
|
configuration adjustments and memory layout experimentation.
|
|
|
|
Build
|
|
=====
|
|
|
|
make bcm7445_defconfig
|
|
make
|
|
${CROSS_COMPILE}strip u-boot
|
|
|
|
Run
|
|
===
|
|
|
|
Flash the u-boot binary into board storage, then invoke it from BOLT.
|
|
For example:
|
|
|
|
BOLT> boot -bsu -elf flash0.u-boot1
|
|
|
|
This port assumes that I-cache and D-cache are already enabled when
|
|
U-Boot is entered.
|
|
|
|
Flattened Image Tree Support
|
|
============================
|
|
|
|
What follows is an example FIT image source file. Build it with:
|
|
|
|
mkimage -f image.its image.itb
|
|
|
|
Booting the resulting image.itb was tested on BOLT v1.20, with the
|
|
following kernels:
|
|
|
|
https://github.com/Broadcom/stblinux-3.14
|
|
https://github.com/Broadcom/stblinux-4.1
|
|
https://github.com/Broadcom/stblinux-4.9
|
|
|
|
and with a generic ARMv7 root file system.
|
|
|
|
image.its:
|
|
/dts-v1/;
|
|
/ {
|
|
description = "BCM7445 FIT";
|
|
images {
|
|
kernel@1 {
|
|
description = "Linux kernel";
|
|
/*
|
|
* This kernel image output format can be
|
|
* generated with:
|
|
*
|
|
* make vmlinux
|
|
* ${CROSS_COMPILE}objcopy -O binary -S vmlinux vmlinux.bin
|
|
* gzip -9 vmlinux.bin
|
|
*
|
|
* For stblinux-3.14, the specific Broadcom
|
|
* board type should be configured in the
|
|
* kernel, for example CONFIG_BCM7445D0=y.
|
|
*/
|
|
data = /incbin/("<vmlinux.bin.gz>");
|
|
type = "kernel";
|
|
arch = "arm";
|
|
os = "linux";
|
|
compression = "gzip";
|
|
load = <0x8000>;
|
|
entry = <0x8000>;
|
|
hash@1 {
|
|
algo = "sha256";
|
|
};
|
|
};
|
|
ramdisk@1 {
|
|
description = "Initramfs root file system";
|
|
data = /incbin/("<initramfs.cpio.gz>");
|
|
type = "ramdisk";
|
|
arch = "arm";
|
|
os = "linux";
|
|
compression = "gzip";
|
|
/*
|
|
* Set the environment variable initrd_high to
|
|
* 0xffffffff, and set "load" and "entry" here
|
|
* to 0x0 to keep initramfs in-place and to
|
|
* accommodate stblinux bmem/CMA reservations.
|
|
*/
|
|
load = <0x0>;
|
|
entry = <0x0>;
|
|
hash@1 {
|
|
algo = "sha256";
|
|
};
|
|
};
|
|
fdt@1 {
|
|
description = "Device tree dumped from BOLT";
|
|
/*
|
|
* This DTB should be similar to the
|
|
* BOLT-generated device tree, after BOLT has
|
|
* done its runtime modifications to it. For
|
|
* example, it can be dumped from within
|
|
* U-Boot (at ${fdtcontroladdr}), after BOLT
|
|
* has loaded U-Boot. The result can be added
|
|
* to the Linux source tree as a .dts file.
|
|
*
|
|
* To support modifications to the device tree
|
|
* in-place in U-Boot, add to Linux's
|
|
* arch/arm/boot/dts/Makefile:
|
|
*
|
|
* DTC_FLAGS ?= -p 4096
|
|
*
|
|
* This will leave some padding in the DTB and
|
|
* thus reserve room for node additions.
|
|
*
|
|
* Also, set the environment variable fdt_high
|
|
* to 0xffffffff to keep the DTB in-place and
|
|
* to accommodate stblinux bmem/CMA
|
|
* reservations.
|
|
*/
|
|
data = /incbin/("<bolt-<version>.dtb");
|
|
type = "flat_dt";
|
|
arch = "arm";
|
|
compression = "none";
|
|
hash@1 {
|
|
algo = "sha256";
|
|
};
|
|
};
|
|
};
|
|
configurations {
|
|
default = "conf@bcm7445";
|
|
conf@bcm7445 {
|
|
description = "BCM7445 configuration";
|
|
kernel = "kernel@1";
|
|
ramdisk = "ramdisk@1";
|
|
fdt = "fdt@1";
|
|
};
|
|
};
|
|
};
|