sh: intc: Drop the use of irq_create_identity_mapping()

Instead of playing games with using irq_create_identity_mapping()
and irq_domain_associate(), drop the use of the former and only
use the latter, together with the allocation of the irq_desc
as needed.

It doesn't make the code less awful, but at least the intent
is clearer.
Tested-by: Geert Uytterhoeven <geert+renesas@glider.be>
Signed-off-by: Marc Zyngier <maz@kernel.org>

drivers/sh/intc/core.c

@@ -179,6 +179,21 @@ static unsigned int __init save_reg(struct intc_desc_int *d,
 	return 0;
 }
 
+static bool __init intc_map(struct irq_domain *domain, int irq)
+{
+	if (!irq_to_desc(irq) && irq_alloc_desc_at(irq, NUMA_NO_NODE) != irq) {
+		pr_err("uname to allocate IRQ %d\n", irq);
+		return false;
+	}
+
+	if (irq_domain_associate(domain, irq, irq)) {
+		pr_err("domain association failure\n");
+		return false;
+	}
+
+	return true;
+}
+
 int __init register_intc_controller(struct intc_desc *desc)
 {
 	unsigned int i, k, smp;
@@ -311,24 +326,12 @@ int __init register_intc_controller(struct intc_desc *desc)
 	for (i = 0; i < hw->nr_vectors; i++) {
 		struct intc_vect *vect = hw->vectors + i;
 		unsigned int irq = evt2irq(vect->vect);
-		int res;
 
 		if (!vect->enum_id)
 			continue;
 
-		res = irq_create_identity_mapping(d->domain, irq);
-		if (unlikely(res)) {
-			if (res == -EEXIST) {
-				res = irq_domain_associate(d->domain, irq, irq);
-				if (unlikely(res)) {
-					pr_err("domain association failure\n");
-					continue;
-				}
-			} else {
-				pr_err("can't identity map IRQ %d\n", irq);
-				continue;
-			}
-		}
+		if (!intc_map(d->domain, irq))
+			continue;
 
 		intc_irq_xlate_set(irq, vect->enum_id, d);
 		intc_register_irq(desc, d, vect->enum_id, irq);
@@ -345,22 +348,8 @@ int __init register_intc_controller(struct intc_desc *desc)
 			 * IRQ support, each vector still needs to have
 			 * its own backing irq_desc.
 			 */
-			res = irq_create_identity_mapping(d->domain, irq2);
-			if (unlikely(res)) {
-				if (res == -EEXIST) {
-					res = irq_domain_associate(d->domain,
-								   irq2, irq2);
-					if (unlikely(res)) {
-						pr_err("domain association "
-						       "failure\n");
-						continue;
-					}
-				} else {
-					pr_err("can't identity map IRQ %d\n",
-					       irq);
-					continue;
-				}
-			}
+			if (!intc_map(d->domain, irq2))
+				continue;
 
 			vect2->enum_id = 0;