arm: 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-arm/Kconfig

@@ -5,5 +5,9 @@ config SYS_TEXT_BASE
 
 config BOARD_SPECIFIC_OPTIONS # dummy
 	def_bool y
+	imply VIRTIO_MMIO
+	imply VIRTIO_PCI
+	imply VIRTIO_NET
+	imply VIRTIO_BLK
 
 endif

board/emulation/qemu-arm/qemu-arm.c

@@ -2,8 +2,12 @@
 /*
  * Copyright (c) 2017 Tuomas Tynkkynen
  */
+
 #include <common.h>
+#include <dm.h>
 #include <fdtdec.h>
+#include <virtio_types.h>
+#include <virtio.h>
 
 #ifdef CONFIG_ARM64
 #include <asm/armv8/mmu.h>
@@ -58,6 +62,12 @@ struct mm_region *mem_map = qemu_arm64_mem_map;
 
 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;
 }