x86: dt: Use linear irq domain for ioapic(s)

The former conversion to irq_domain_add_legacy() did not fully work
since we miss the irq decs for NR_IRQS_LEGACY+.

Ideally we could use irq_domain_add_simple() or the no-map variant (and
program the virq <-> line mapping directly into ioapic) but this would
require a different irq lookup in "do_IRQ()" and won't work with ACPI
without changes. So this is probably easiest for everyone.
Tested-by: Thierry Reding <thierry.reding@avionic-design.de>
Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Cc: Grant Likely <grant.likely@secretlab.ca>
Link: http://lkml.kernel.org/r/20120813202304.GA3529@breakpoint.ccSigned-off-by: Thomas Gleixner <tglx@linutronix.de>

arch/x86/kernel/devicetree.c

@@ -342,6 +342,47 @@ const struct irq_domain_ops ioapic_irq_domain_ops = {
 	.xlate = ioapic_xlate,
 };
 
+static void dt_add_ioapic_domain(unsigned int ioapic_num,
+		struct device_node *np)
+{
+	struct irq_domain *id;
+	struct mp_ioapic_gsi *gsi_cfg;
+	int ret;
+	int num;
+
+	gsi_cfg = mp_ioapic_gsi_routing(ioapic_num);
+	num = gsi_cfg->gsi_end - gsi_cfg->gsi_base + 1;
+
+	id = irq_domain_add_linear(np, num, &ioapic_irq_domain_ops,
+			(void *)ioapic_num);
+	BUG_ON(!id);
+	if (gsi_cfg->gsi_base == 0) {
+		/*
+		 * The first NR_IRQS_LEGACY irq descs are allocated in
+		 * early_irq_init() and need just a mapping. The
+		 * remaining irqs need both. All of them are preallocated
+		 * and assigned so we can keep the 1:1 mapping which the ioapic
+		 * is having.
+		 */
+		ret = irq_domain_associate_many(id, 0, 0, NR_IRQS_LEGACY);
+		if (ret)
+			pr_err("Error mapping legacy IRQs: %d\n", ret);
+
+		if (num > NR_IRQS_LEGACY) {
+			ret = irq_create_strict_mappings(id, NR_IRQS_LEGACY,
+					NR_IRQS_LEGACY, num - NR_IRQS_LEGACY);
+			if (ret)
+				pr_err("Error creating mapping for the "
+						"remaining IRQs: %d\n", ret);
+		}
+		irq_set_default_host(id);
+	} else {
+		ret = irq_create_strict_mappings(id, gsi_cfg->gsi_base, 0, num);
+		if (ret)
+			pr_err("Error creating IRQ mapping: %d\n", ret);
+	}
+}
+
 static void __init ioapic_add_ofnode(struct device_node *np)
 {
 	struct resource r;
@@ -356,15 +397,7 @@ static void __init ioapic_add_ofnode(struct device_node *np)
 
 	for (i = 0; i < nr_ioapics; i++) {
 		if (r.start == mpc_ioapic_addr(i)) {
-			struct irq_domain *id;
-			struct mp_ioapic_gsi *gsi_cfg;
-
-			gsi_cfg = mp_ioapic_gsi_routing(i);
-
-			id = irq_domain_add_legacy(np, 32, gsi_cfg->gsi_base, 0,
-						   &ioapic_irq_domain_ops,
-						   (void*)i);
-			BUG_ON(!id);
+			dt_add_ioapic_domain(i, np);
 			return;
 		}
 	}