riscv: qemu: Enumerate virtio bus during early boot

Currently devices on the virtio bus is not automatically enumerated,
which means peripherals on the virtio bus are not discovered by their
drivers. This uses board_init() to do the virtio enumeration.

Signed-off-by: Bin Meng <bmeng.cn@gmail.com>
Reviewed-by: Simon Glass <sjg@chromium.org>

board/emulation/qemu-riscv/Kconfig

@@ -18,5 +18,8 @@ config SYS_TEXT_BASE
 config BOARD_SPECIFIC_OPTIONS # dummy
 	def_bool y
 	imply SYS_NS16550
+	imply VIRTIO_MMIO
+	imply VIRTIO_NET
+	imply VIRTIO_BLK
 
 endif

board/emulation/qemu-riscv/qemu-riscv.c

@@ -4,12 +4,21 @@
  */
 
 #include <common.h>
+#include <dm.h>
 #include <fdtdec.h>
+#include <virtio_types.h>
+#include <virtio.h>
 
 #define MROM_FDT_ADDR	0x1020
 
 int board_init(void)
 {
+	/*
+	 * Make sure virtio bus is enumerated so that peripherals
+	 * on the virtio bus can be discovered by their drivers
+	 */
+	virtio_init();
+
 	return 0;
 }