irqchip/gicv3-its: platform-msi: Refactor its_pmsi_init() to prepare for ACPI

Introduce its_pmsi_init_one() to separate firmware dependent
code (ie OF dependent code) and firmware agnostic code so
that gic3-its code can be made to support other firmware
bindings easily.
Signed-off-by: Hanjun Guo <hanjun.guo@linaro.org>
[lorenzo.pieralisi@arm.com: rewrote commit log]
Signed-off-by: Lorenzo Pieralisi <lorenzo.pieralisi@arm.com>
Reviewed-by: Matthias Brugger <mbrugger@suse.com>
Tested-by: Ming Lei <ming.lei@canonical.com>
Tested-by: Wei Xu <xuwei5@hisilicon.com>
Tested-by: Sinan Kaya <okaya@codeaurora.org>
Cc: Tomasz Nowicki <tn@semihalf.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Marc Zyngier <marc.zyngier@arm.com>

drivers/irqchip/irq-gic-v3-its-platform-msi.c

@@ -82,34 +82,43 @@ static struct of_device_id its_device_id[] = {
 	{},
 };
 
-static int __init its_pmsi_init(void)
+static int __init its_pmsi_init_one(struct fwnode_handle *fwnode,
+				const char *name)
 {
-	struct device_node *np;
 	struct irq_domain *parent;
 
+	parent = irq_find_matching_fwnode(fwnode, DOMAIN_BUS_NEXUS);
+	if (!parent || !msi_get_domain_info(parent)) {
+		pr_err("%s: unable to locate ITS domain\n", name);
+		return -ENXIO;
+	}
+
+	if (!platform_msi_create_irq_domain(fwnode, &its_pmsi_domain_info,
+					    parent)) {
+		pr_err("%s: unable to create platform domain\n", name);
+		return -ENXIO;
+	}
+
+	pr_info("Platform MSI: %s domain created\n", name);
+	return 0;
+}
+
+static void __init its_pmsi_of_init(void)
+{
+	struct device_node *np;
+
 	for (np = of_find_matching_node(NULL, its_device_id); np;
 	     np = of_find_matching_node(np, its_device_id)) {
 		if (!of_property_read_bool(np, "msi-controller"))
 			continue;
 
-		parent = irq_find_matching_host(np, DOMAIN_BUS_NEXUS);
-		if (!parent || !msi_get_domain_info(parent)) {
-			pr_err("%s: unable to locate ITS domain\n",
-			       np->full_name);
-			continue;
-		}
-
-		if (!platform_msi_create_irq_domain(of_node_to_fwnode(np),
-						    &its_pmsi_domain_info,
-						    parent)) {
-			pr_err("%s: unable to create platform domain\n",
-			       np->full_name);
-			continue;
-		}
-
-		pr_info("Platform MSI: %s domain created\n", np->full_name);
+		its_pmsi_init_one(of_node_to_fwnode(np), np->full_name);
 	}
+}
 
+static int __init its_pmsi_init(void)
+{
+	its_pmsi_of_init();
 	return 0;
 }
 early_initcall(its_pmsi_init);