ARCv2: intc: IDU: support irq affinity

With this nsim standlone / OSCI have working irq affinity - AXS103 still
needs some work as IDU is not visible in intc hierarchy yet !
Signed-off-by: Vineet Gupta <vgupta@synopsys.com>

arch/arc/kernel/mcip.c

@@ -218,11 +218,28 @@ static void idu_irq_unmask(struct irq_data *data)
 	raw_spin_unlock_irqrestore(&mcip_lock, flags);
 }
 
+#ifdef CONFIG_SMP
 static int
-idu_irq_set_affinity(struct irq_data *d, const struct cpumask *cpumask, bool f)
+idu_irq_set_affinity(struct irq_data *data, const struct cpumask *cpumask,
+		     bool force)
 {
+	unsigned long flags;
+	cpumask_t online;
+
+	/* errout if no online cpu per @cpumask */
+	if (!cpumask_and(&online, cpumask, cpu_online_mask))
+		return -EINVAL;
+
+	raw_spin_lock_irqsave(&mcip_lock, flags);
+
+	idu_set_dest(data->hwirq, cpumask_bits(&online)[0]);
+	idu_set_mode(data->hwirq, IDU_M_TRIG_LEVEL, IDU_M_DISTRI_RR);
+
+	raw_spin_unlock_irqrestore(&mcip_lock, flags);
+
 	return IRQ_SET_MASK_OK;
 }
+#endif
 
 static struct irq_chip idu_irq_chip = {
 	.name			= "MCIP IDU Intc",