csky: IRQ handling

This patch adds IRQ handling files.

Signed-off-by: Guo Ren <ren_guo@c-sky.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Reviewed-by: Arnd Bergmann <arnd@arndb.de>

arch/csky/kernel/irq.c

@@ -0,0 +1,22 @@
+// SPDX-License-Identifier: GPL-2.0
+// Copyright (C) 2018 Hangzhou C-SKY Microsystems co.,ltd.
+
+#include <linux/init.h>
+#include <linux/interrupt.h>
+#include <linux/irq.h>
+#include <linux/irqchip.h>
+#include <asm/traps.h>
+#include <asm/smp.h>
+
+void __init init_IRQ(void)
+{
+	irqchip_init();
+#ifdef CONFIG_SMP
+	setup_smp_ipi();
+#endif
+}
+
+asmlinkage void __irq_entry csky_do_IRQ(struct pt_regs *regs)
+{
+	handle_arch_irq(regs);
+}