irqchip: loongarch-cpu: add DT support

LoongArch is coming to support booting with FDT, so DT
support of this driver is desired.
Signed-off-by: Liu Peibao <liupeibao@loongson.cn>
Signed-off-by: Marc Zyngier <maz@kernel.org>
Link: https://lore.kernel.org/r/20221114113824.1880-2-liupeibao@loongson.cn

drivers/irqchip/irq-loongarch-cpu.c

@@ -92,6 +92,25 @@ static const struct irq_domain_ops loongarch_cpu_intc_irq_domain_ops = {
 	.xlate = irq_domain_xlate_onecell,
 };
 
+#ifdef CONFIG_OF
+int __init loongarch_cpu_irq_of_init(struct device_node *of_node,
+				struct device_node *parent)
+{
+	cpuintc_handle = of_node_to_fwnode(of_node);
+
+	irq_domain = irq_domain_create_linear(cpuintc_handle, EXCCODE_INT_NUM,
+				&loongarch_cpu_intc_irq_domain_ops, NULL);
+	if (!irq_domain)
+		panic("Failed to add irqdomain for loongarch CPU");
+
+	set_handle_irq(&handle_cpu_irq);
+
+	return 0;
+}
+IRQCHIP_DECLARE(cpu_intc, "loongson,cpu-interrupt-controller",
+					loongarch_cpu_irq_of_init);
+#endif
+
 static int __init
 liointc_parse_madt(union acpi_subtable_headers *header,
 		       const unsigned long end)