tools: Add mkimage-rpi3 to build images for raspberry Pi 3

The package contains u-boot and the RPi firmware blobs. It expects
a tar ball of the root filesystem (including kernel and dtbs) on stdin
and produces a compressed tar ball on stdout with the files to copy to
a FAT32 formatted SD card.

Signed-off-by: Rolf Neugebauer <rolf.neugebauer@docker.com>

tools/mkimage-rpi3/Dockerfile

@@ -0,0 +1,56 @@
+FROM linuxkit/alpine:b3f8da6c6f02440ee9c4c72bbf4dabdf500b1d8c as build
+RUN apk add \
+    bc \
+    dtc \
+    curl \
+    make \
+    gcc \
+    git \
+    musl-dev \
+    patch
+
+# Create small rootfs
+RUN mkdir -p /out/etc/apk && cp -r /etc/apk/* /out/etc/apk/
+RUN apk add --no-cache --initdb -p /out \
+    alpine-baselayout \
+    busybox \
+    libarchive-tools \
+    musl \
+    tar
+RUN rm -rf /out/etc/apk /out/lib/apk /out/var/cache
+
+# u-boot compile. The patch is needed to handle larger kernels
+ENV UBOOT_COMMIT=v2017.09
+COPY u-boot.patch .
+RUN git clone https://github.com/u-boot/u-boot.git && \
+    cd /u-boot && \
+    git checkout $UBOOT_COMMIT
+WORKDIR /u-boot
+RUN patch -p 1 < /u-boot.patch && \
+    make rpi_3_defconfig all && \
+    mkdir -p /out/boot && \
+    cp u-boot.bin /out/boot && \
+    mkdir -p /out/bin && \
+    cp tools/mkimage /out/bin
+
+# fetch the Raspberry Pi 3 firmware (latest master)
+ENV RPI_COMMIT=478d637c476e838ffcfa8535232ff0b86daf5918
+RUN mkdir -p /out/boot && \
+    cd /out/boot && \
+    curl -fsSLO https://github.com/raspberrypi/firmware/raw/$RPI_COMMIT/boot/bootcode.bin && \
+    curl -fsSLO https://github.com/raspberrypi/firmware/raw/$RPI_COMMIT/boot/bootcode.bin && \
+    curl -fsSLO https://github.com/raspberrypi/firmware/raw/$RPI_COMMIT/boot/fixup_cd.dat && \
+    curl -fsSLO https://github.com/raspberrypi/firmware/raw/$RPI_COMMIT/boot/fixup.dat && \
+    curl -fsSLO https://github.com/raspberrypi/firmware/raw/$RPI_COMMIT/boot/fixup_x.dat && \
+    curl -fsSLO https://github.com/raspberrypi/firmware/raw/$RPI_COMMIT/boot/start_cd.elf && \
+    curl -fsSLO https://github.com/raspberrypi/firmware/raw/$RPI_COMMIT/boot/start.elf && \
+    curl -fsSLO https://github.com/raspberrypi/firmware/raw/$RPI_COMMIT/boot/start_x.elf
+
+FROM scratch
+ENTRYPOINT []
+CMD []
+WORKDIR /
+COPY --from=build /out/ /
+COPY config.txt boot.script /boot/
+COPY make-rpi3 /
+ENTRYPOINT [ "/make-rpi3" ]

tools/mkimage-rpi3/boot.script

@@ -0,0 +1,9 @@
+setenv bootargs "dwc_otg.lpm_enable=0 earlyprintk console=tty1 console=ttyS0,115200 root=/dev/ram0 rw"
+setenv dtbfile bcm2837-rpi-3-b.dtb
+setenv machid 0x00000c42
+saveenv
+
+fatload mmc 0:1 ${kernel_addr_r} kernel.uimg
+fatload mmc 0:1 ${fdt_addr_r} ${dtbfile}
+fatload mmc 0:1 ${ramdisk_addr_r} initrd.uimg
+bootm ${kernel_addr_r} ${ramdisk_addr_r} ${fdt_addr_r}

tools/mkimage-rpi3/build.yml

@@ -0,0 +1,4 @@
+image: mkimage-rpi3
+network: true
+arches:
+  - arm64

tools/mkimage-rpi3/config.txt

@@ -0,0 +1,5 @@
+avoid_warnings=2
+# 64bit mode, serial and kernel
+arm_control=0x200
+enable_uart=1
+kernel=u-boot.bin

tools/mkimage-rpi3/make-rpi3

@@ -0,0 +1,29 @@
+#!/bin/sh
+
+set -e
+
+# input is a tarball on stdin with kernel, dtbs and cmdline in /boot
+# output is an tar to be extracted onto a SD card
+
+mkdir -p /files 
+cd /files
+
+# extract. BSD tar auto recognises compression
+[ -t 0 ] || bsdtar xzf -
+
+cd /
+
+# copy/convert files 
+cp /files/boot/dtb/broadcom/bcm2837-rpi-3-b.dtb /boot
+/bin/mkimage -A arm64 -O linux -T kernel -C gzip -a 0x80000 -e 0x80000 \
+             -d /files/boot/kernel /boot/kernel.uimg >> /boot/uboot.log
+/bin/mkimage -A arm64 -O linux -T script -C none -a 0x00000000 -e 0x00000000 -n RPi3 \
+             -d /boot/boot.script /boot/boot.scr  >> /boot/uboot.log
+
+# build an initrd and convert it
+rm -rf /files/boot
+cd /files && find . | cpio -o -H newc | gzip > /initrd.img
+/bin/mkimage -A arm64 -O linux -T ramdisk -d /initrd.img /boot/initrd.uimg  >> /boot/uboot.log
+
+# now everything is setup in /boot just need to tar it
+cd /boot && tar cf - .

tools/mkimage-rpi3/u-boot.patch

@@ -0,0 +1,11 @@
+diff --git a/include/configs/rpi.h b/include/configs/rpi.h
+index c499b45..1faae3c 100644
+--- a/include/configs/rpi.h
++++ b/include/configs/rpi.h
+@@ -161,4 +161,6 @@
+ 	BOOTENV
+ 
+ 
++#define CONFIG_SYS_BOOTM_LEN (64 * 1024 * 1024)
++
+ #endif