irqchip: i8259: Add domain before mapping parent irq

Mapping the parent IRQ will use a virq number which may conflict with
the hardcoded I8259A_IRQ_BASE..I8259A_IRQ_BASE+15 range that the i8259
driver expects to be free. If this occurs then we'll hit errors when
adding the i8259 IRQ domain, since one of its virq numbers will already
be in use.

Avoid this by adding the i8259 domain before mapping the parent IRQ,
such that the i8259 virq numbers become used before the parent interrupt
controller gets a chance to use any of them.
Signed-off-by: Paul Burton <paul.burton@imgtec.com>
Acked-by: Thomas Gleixner <tglx@linutronix.de>
Cc: Marc Zyngier <marc.zyngier@arm.com>
Cc: Jason Cooper <jason@lakedaemon.net>
Cc: linux-mips@linux-mips.org
Cc: linux-kernel@vger.kernel.org
Patchwork: https://patchwork.linux-mips.org/patch/14269/Signed-off-by: Ralf Baechle <ralf@linux-mips.org>

drivers/irqchip/irq-i8259.c

@@ -370,13 +370,15 @@ int __init i8259_of_init(struct device_node *node, struct device_node *parent)
 	struct irq_domain *domain;
 	unsigned int parent_irq;
 
+	domain = __init_i8259_irqs(node);
+
 	parent_irq = irq_of_parse_and_map(node, 0);
 	if (!parent_irq) {
 		pr_err("Failed to map i8259 parent IRQ\n");
+		irq_domain_remove(domain);
 		return -ENODEV;
 	}
 
-	domain = __init_i8259_irqs(node);
 	irq_set_chained_handler_and_data(parent_irq, i8259_irq_dispatch,
 					 domain);
 	return 0;