riscv: qemu: Add platform-specific Kconfig options

Add the QEMU RISC-V platform-specific Kconfig options, to include
CPU and timer drivers.

Signed-off-by: Bin Meng <bmeng.cn@gmail.com>
Reviewed-by: Lukas Auer <lukas.auer@aisec.fraunhofer.de>
Reviewed-by: Anup Patel <anup@brainfault.org>

arch/riscv/Kconfig

@@ -22,6 +22,7 @@ source "board/emulation/qemu-riscv/Kconfig"
 
 # platform-specific options below
 source "arch/riscv/cpu/ax25/Kconfig"
+source "arch/riscv/cpu/qemu/Kconfig"
 
 # architecture-specific options below
 

arch/riscv/cpu/qemu/Kconfig

@@ -0,0 +1,11 @@
+# SPDX-License-Identifier: GPL-2.0+
+#
+# Copyright (C) 2018, Bin Meng <bmeng.cn@gmail.com>
+
+config QEMU_RISCV
+	bool
+	imply CPU
+	imply CPU_RISCV
+	imply RISCV_TIMER
+	imply SIFIVE_CLINT if RISCV_MMODE
+	imply CMD_CPU

board/emulation/qemu-riscv/Kconfig

@@ -18,6 +18,7 @@ config SYS_TEXT_BASE
 
 config BOARD_SPECIFIC_OPTIONS # dummy
 	def_bool y
+	select QEMU_RISCV
 	imply SYS_NS16550
 	imply VIRTIO_MMIO
 	imply VIRTIO_NET