nds32: IRQ handling

This patch includes irq related functions and irqchip_init().
Signed-off-by: Vincent Chen <vincentc@andestech.com>
Signed-off-by: Greentime Hu <greentime@andestech.com>
Acked-by: Arnd Bergmann <arnd@arndb.de>

arch/nds32/include/asm/irqflags.h

+// SPDX-License-Identifier: GPL-2.0
+// Copyright (C) 2005-2017 Andes Technology Corporation
+
+#include <asm/nds32.h>
+#include <nds32_intrinsic.h>
+
+#define arch_local_irq_disable()	\
+	GIE_DISABLE();
+
+#define arch_local_irq_enable()	\
+	GIE_ENABLE();
+static inline unsigned long arch_local_irq_save(void)
+{
+	unsigned long flags;
+	flags = __nds32__mfsr(NDS32_SR_PSW) & PSW_mskGIE;
+	GIE_DISABLE();
+	return flags;
+}
+
+static inline unsigned long arch_local_save_flags(void)
+{
+	unsigned long flags;
+	flags = __nds32__mfsr(NDS32_SR_PSW) & PSW_mskGIE;
+	return flags;
+}
+
+static inline void arch_local_irq_restore(unsigned long flags)
+{
+	if(flags)
+		GIE_ENABLE();
+}
+
+static inline int arch_irqs_disabled_flags(unsigned long flags)
+{
+	return !flags;
+}

arch/nds32/kernel/irq.c

+// SPDX-License-Identifier: GPL-2.0
+// Copyright (C) 2005-2017 Andes Technology Corporation
+
+#include <linux/irqchip.h>
+
+void __init init_IRQ(void)
+{
+	irqchip_init();
+}