New port: sysutils/u-boot-qemu-riscv64

Add a u-boot port for QEMU's 64-bit RISC-V config. A simple u-boot
payload is provided that can be specified on the command line. It runs
in supervisor mode, and should be paired with OpenSBI.

Reviewed by:	manu
Approved by:	u-boot (manu)
Differential Revision:	https://reviews.freebsd.org/D25737

sysutils/Makefile

@@ -1364,6 +1364,7 @@
     SUBDIR += u-boot-pinebookpro
     SUBDIR += u-boot-qemu-arm
     SUBDIR += u-boot-qemu-arm64
+    SUBDIR += u-boot-qemu-riscv64
     SUBDIR += u-boot-riotboard
     SUBDIR += u-boot-rock64
     SUBDIR += u-boot-rockpro64

sysutils/u-boot-qemu-riscv64/Makefile

@@ -0,0 +1,10 @@
+# $FreeBSD$
+
+MASTERDIR=	${.CURDIR}/../u-boot-master
+
+MODEL=		qemu-riscv64
+BOARD_CONFIG=	qemu-riscv64_smode_defconfig
+FAMILY=		qemu
+UBOOT_ARCH=	riscv64
+
+.include "${MASTERDIR}/Makefile"

sysutils/u-boot-qemu-riscv64/pkg-descr

@@ -0,0 +1,12 @@
+U-Boot loader for QEMU RISC-V 64-bit
+
+To use this bootloader to boot a FreeBSD RISC-V image, install
+emulators/qemu50 and sysutils/opensbi and execute it as:
+
+qemu-system-riscv64 -machine virt -m 2048m -smp 2 -nographic \
+    -bios /usr/local/share/opensbi/lp64/generic/firmware/fw_jump.elf \
+    -kernel /usr/local/share/u-boot/u-boot-qemu-riscv64/u-boot.bin \
+    -drive file=/path/to/freebsd.img,format=raw,id=hd0 \
+    -device virtio-blk-device,drive=hd0
+
+WWW: https://www.denx.de/wiki/U-Boot