riscv: cpu: fu740: Add support for cpu fu740

Add SiFive fu740 cpu to support RISC-V arch

Signed-off-by: Green Wan <green.wan@sifive.com>
Reviewed-by: Bin Meng <bmeng.cn@gmail.com>
diff --git a/arch/riscv/cpu/fu740/cpu.c b/arch/riscv/cpu/fu740/cpu.c
new file mode 100644
index 0000000..f13c189
--- /dev/null
+++ b/arch/riscv/cpu/fu740/cpu.c
@@ -0,0 +1,22 @@
+// SPDX-License-Identifier: GPL-2.0+
+/*
+ * Copyright (C) 2018, Bin Meng <bmeng.cn@gmail.com>
+ */
+
+#include <irq_func.h>
+#include <asm/cache.h>
+
+/*
+ * cleanup_before_linux() is called just before we call linux
+ * it prepares the processor for linux
+ *
+ * we disable interrupt and caches.
+ */
+int cleanup_before_linux(void)
+{
+	disable_interrupts();
+
+	cache_flush();
+
+	return 0;
+}