configs/visionfive2_defconfig: new defconfig

Add a defconfig for the Starfive VisionFive2 board, a board built around the
Starfive JH7110 RISC-V 64bit SoC.

This board comes with functional lowlevel and U-Boot bootloaders in SPI
flash. The defconfig reuses these and only builds a (5.15 based) kernel and
rootfs.

The factory shipped U-Boot is hard coded to look at MMC partition 3.

Signed-off-by: Francois Dugast <francois.dugast.foss@gmail.com>
[Peter: add to DEVELOPERS]
Signed-off-by: Peter Korsgaard <peter@korsgaard.com>

DEVELOPERS

@@ -1029,6 +1029,10 @@ F:	package/tbb/
 N:	Francisco Gonzalez <gzmorell@gmail.com>
 F:	package/ser2net/
 
+N:	Francois Dugast <francois.dugast.foss@gmail.com>
+F:	board/visionfive2/
+F:	configs/visionfive2_defconfig
+
 N:	Francois Perrad <francois.perrad@gadz.org>
 F:	board/freescale/ls1028ardb/
 F:	board/olimex/a20_olinuxino

board/visionfive2/genimage.cfg

@@ -0,0 +1,21 @@
+# Minimal SD card image for the Starfive VisionFive2 board
+
+image sdcard.img {
+	hdimage {
+	}
+
+	# u-boot is hard coded to look at 3rd partition
+	partition dummy1 {
+		size = 512
+	}
+
+	partition dummy2 {
+		size = 512
+	}
+
+	partition rootfs {
+		partition-type = 0x83
+		image = "rootfs.ext4"
+		bootable = "true"
+	}
+}

board/visionfive2/overlay/boot/extlinux/extlinux.conf

@@ -0,0 +1,4 @@
+label linux
+  kernel /boot/Image
+  devicetree /boot/jh7110-visionfive-v2.dtb
+  append console=ttyS0,115200 root=/dev/mmcblk1p3

board/visionfive2/readme.txt

@@ -0,0 +1,30 @@
+Starfive VisionFive2
+====================
+
+The VisionFive2 is a low-cost RISC-V 64-bit based platform, powered by a
+Starfive JH7110 processor.
+
+How to build
+============
+
+$ make visionfive2_defconfig
+$ make
+
+How to write the SD card
+========================
+
+Once the build process is finished you will have an image called "sdcard.img"
+in the output/images/ directory.
+
+Copy the bootable "sdcard.img" onto an SD card with "dd":
+
+  $ sudo dd if=output/images/sdcard.img of=/dev/sdX
+
+Preparing the board
+===================
+
+Connect a TTL UART cable to pin 6 (GND), 8 (TX) and 10 (RX).
+
+Insert your SD card.
+
+Power-up the board using an USB-C cable.

configs/visionfive2_defconfig

@@ -0,0 +1,18 @@
+BR2_riscv=y
+BR2_PACKAGE_HOST_LINUX_HEADERS_CUSTOM_5_15=y
+BR2_SYSTEM_DHCP="eth0"
+BR2_ROOTFS_OVERLAY="board/visionfive2/overlay"
+BR2_ROOTFS_POST_IMAGE_SCRIPT="support/scripts/genimage.sh"
+BR2_ROOTFS_POST_SCRIPT_ARGS="-c board/visionfive/genimage.cfg"
+BR2_LINUX_KERNEL=y
+BR2_LINUX_KERNEL_CUSTOM_TARBALL=y
+BR2_LINUX_KERNEL_CUSTOM_TARBALL_LOCATION="$(call github,starfive-tech,linux,7b7b4eddd8d5ae55f6e0ee09b93e16e23ab4f97b)/linux-7b7b4eddd8d5ae55f6e0ee09b93e16e23ab4f97b.tar.gz"
+BR2_LINUX_KERNEL_DEFCONFIG="starfive_visionfive2"
+BR2_LINUX_KERNEL_DTS_SUPPORT=y
+BR2_LINUX_KERNEL_INTREE_DTS_NAME="starfive/jh7110-visionfive-v2"
+BR2_LINUX_KERNEL_INSTALL_TARGET=y
+BR2_LINUX_KERNEL_NEEDS_HOST_OPENSSL=y
+BR2_TARGET_ROOTFS_EXT2=y
+BR2_TARGET_ROOTFS_EXT2_4=y
+# BR2_TARGET_ROOTFS_TAR is not set
+BR2_PACKAGE_HOST_GENIMAGE=y