x86/ioapic: Create named irq domain

Use the fwnode to create a named domain so diagnosis works, but only when
the the ioapic is not device tree based.
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Cc: Jens Axboe <axboe@kernel.dk>
Cc: Marc Zyngier <marc.zyngier@arm.com>
Cc: Michael Ellerman <mpe@ellerman.id.au>
Cc: Keith Busch <keith.busch@intel.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Christoph Hellwig <hch@lst.de>
Link: http://lkml.kernel.org/r/20170619235443.752782603@linutronix.deSigned-off-by: Thomas Gleixner <tglx@linutronix.de>

arch/x86/kernel/apic/io_apic.c

@@ -2223,6 +2223,8 @@ static int mp_irqdomain_create(int ioapic)
 	struct ioapic *ip = &ioapics[ioapic];
 	struct ioapic_domain_cfg *cfg = &ip->irqdomain_cfg;
 	struct mp_ioapic_gsi *gsi_cfg = mp_ioapic_gsi_routing(ioapic);
+	struct fwnode_handle *fn;
+	char *name = "IO-APIC";
 
 	if (cfg->type == IOAPIC_DOMAIN_INVALID)
 		return 0;
@@ -2233,9 +2235,25 @@ static int mp_irqdomain_create(int ioapic)
 	parent = irq_remapping_get_ir_irq_domain(&info);
 	if (!parent)
 		parent = x86_vector_domain;
+	else
+		name = "IO-APIC-IR";
 
-	ip->irqdomain = irq_domain_add_linear(cfg->dev, hwirqs, cfg->ops,
+	/* Handle device tree enumerated APICs proper */
+	if (cfg->dev) {
+		fn = of_node_to_fwnode(cfg->dev);
+	} else {
+		fn = irq_domain_alloc_named_id_fwnode(name, ioapic);
+		if (!fn)
+			return -ENOMEM;
+	}
+
+	ip->irqdomain = irq_domain_create_linear(fn, hwirqs, cfg->ops,
 						 (void *)(long)ioapic);
+
+	/* Release fw handle if it was allocated above */
+	if (!cfg->dev)
+		irq_domain_free_fwnode(fn);
+
 	if (!ip->irqdomain)
 		return -ENOMEM;