ARC: Prepare interrupt code for external controllers

This patch adds some room for CPU-external interrupt controllers in the
Linux interrupt space. Until now, only the 32 CPU internal interrupt lines
were supported which does not allow for external interrupt controllers such
as GPIO modules etc.

Signed-off-by: Christian Ruppert <christian.ruppert@abilis.com>
Signed-off-by: Pierrick Hascoet <pierrick.hascoet@abilis.com>
Signed-off-by: Vineet Gupta <vgupta@synopsys.com>

arch/arc/include/asm/irq.h

@@ -9,7 +9,8 @@
 #ifndef __ASM_ARC_IRQ_H
 #define __ASM_ARC_IRQ_H
 
-#define NR_IRQS		32
+#define NR_CPU_IRQS	32  /* number of interrupt lines of ARC770 CPU */
+#define NR_IRQS		128 /* allow some CPU external IRQ handling */
 
 /* Platform Independent IRQs */
 #define TIMER0_IRQ      3

arch/arc/kernel/irq.c

@@ -105,7 +105,7 @@ init_onchip_IRQ(struct device_node *intc, struct device_node *parent)
 	if (parent)
 		panic("DeviceTree incore intc not a root irq controller\n");
 
-	root_domain = irq_domain_add_legacy(intc, NR_IRQS, 0, 0,
+	root_domain = irq_domain_add_legacy(intc, NR_CPU_IRQS, 0, 0,
 					    &arc_intc_domain_ops, NULL);
 
 	if (!root_domain)