genirq: Provide an accessor for IRQ_PER_CPU flag

Adds an accessor function, irq_is_per_cpu(), for the flag IRQ_PER_CPU.

This is useful if you have an IRQ that is per-cpu in some hardware
implementations, and not in others (example: ARM PMU Interrupts), and
you want to handle both cases.

Change-Id: Ic176ee5b8f9a830c1db35cb939ec659a4cf3f938
Signed-off-by: Chris Smith <chris.smith@st.com>
Signed-off-by: Rohit Vaswani <rvaswani@codeaurora.org>
diff --git a/include/linux/irqdesc.h b/include/linux/irqdesc.h
index f1e2527..771cb35 100644
--- a/include/linux/irqdesc.h
+++ b/include/linux/irqdesc.h
@@ -154,6 +154,14 @@
 	return desc->status_use_accessors & IRQ_NO_BALANCING_MASK;
 }
 
+static inline int irq_is_per_cpu(unsigned int irq)
+{
+	struct irq_desc *desc;
+
+	desc = irq_to_desc(irq);
+	return desc->status_use_accessors & IRQ_PER_CPU;
+}
+
 static inline void
 irq_set_lockdep_class(unsigned int irq, struct lock_class_key *class)
 {