irqchip/exiu: Preparatory refactor for ACPI support

In preparation of adding support for EXIU controller devices described
via ACPI, split the DT init function in a DT specific and a generic part,
where the latter will be reused for ACPI support later.
Signed-off-by: Ard Biesheuvel <ard.biesheuvel@linaro.org>
Signed-off-by: Marc Zyngier <marc.zyngier@arm.com>

drivers/irqchip/irq-sni-exiu.c

 /*
  * Driver for Socionext External Interrupt Unit (EXIU)
  *
- * Copyright (c) 2017 Linaro, Ltd. <ard.biesheuvel@linaro.org>
+ * Copyright (c) 2017-2019 Linaro, Ltd. <ard.biesheuvel@linaro.org>
  *
  * Based on irq-tegra.c:
  *   Copyright (C) 2011 Google, Inc.
@@ -167,35 +167,23 @@ static const struct irq_domain_ops exiu_domain_ops = {
 	.free		= irq_domain_free_irqs_common,
 };
 
-static int __init exiu_init(struct device_node *node,
-			    struct device_node *parent)
+static struct exiu_irq_data *exiu_init(const struct fwnode_handle *fwnode,
+				       struct resource *res)
 {
-	struct irq_domain *parent_domain, *domain;
 	struct exiu_irq_data *data;
 	int err;
 
-	if (!parent) {
-		pr_err("%pOF: no parent, giving up\n", node);
-		return -ENODEV;
-	}
-
-	parent_domain = irq_find_host(parent);
-	if (!parent_domain) {
-		pr_err("%pOF: unable to obtain parent domain\n", node);
-		return -ENXIO;
-	}
-
 	data = kzalloc(sizeof(*data), GFP_KERNEL);
 	if (!data)
-		return -ENOMEM;
+		return ERR_PTR(-ENOMEM);
 
-	if (of_property_read_u32(node, "socionext,spi-base", &data->spi_base)) {
-		pr_err("%pOF: failed to parse 'spi-base' property\n", node);
+	if (fwnode_property_read_u32_array(fwnode, "socionext,spi-base",
+					   &data->spi_base, 1)) {
 		err = -ENODEV;
 		goto out_free;
 	}
 
-	data->base = of_iomap(node, 0);
+	data->base = ioremap(res->start, resource_size(res));
 	if (!data->base) {
 		err = -ENODEV;
 		goto out_free;
@@ -205,11 +193,44 @@ static int __init exiu_init(struct device_node *node,
 	writel_relaxed(0xFFFFFFFF, data->base + EIREQCLR);
 	writel_relaxed(0xFFFFFFFF, data->base + EIMASK);
 
+	return data;
+
+out_free:
+	kfree(data);
+	return ERR_PTR(err);
+}
+
+static int __init exiu_dt_init(struct device_node *node,
+			       struct device_node *parent)
+{
+	struct irq_domain *parent_domain, *domain;
+	struct exiu_irq_data *data;
+	struct resource res;
+
+	if (!parent) {
+		pr_err("%pOF: no parent, giving up\n", node);
+		return -ENODEV;
+	}
+
+	parent_domain = irq_find_host(parent);
+	if (!parent_domain) {
+		pr_err("%pOF: unable to obtain parent domain\n", node);
+		return -ENXIO;
+	}
+
+	if (of_address_to_resource(node, 0, &res)) {
+		pr_err("%pOF: failed to parse memory resource\n", node);
+		return -ENXIO;
+	}
+
+	data = exiu_init(of_node_to_fwnode(node), &res);
+	if (IS_ERR(data))
+		return PTR_ERR(data);
+
 	domain = irq_domain_add_hierarchy(parent_domain, 0, NUM_IRQS, node,
 					  &exiu_domain_ops, data);
 	if (!domain) {
 		pr_err("%pOF: failed to allocate domain\n", node);
-		err = -ENOMEM;
 		goto out_unmap;
 	}
 
@@ -220,8 +241,7 @@ static int __init exiu_init(struct device_node *node,
 
 out_unmap:
 	iounmap(data->base);
-out_free:
 	kfree(data);
-	return err;
+	return -ENOMEM;
 }
-IRQCHIP_DECLARE(exiu, "socionext,synquacer-exiu", exiu_init);
+IRQCHIP_DECLARE(exiu, "socionext,synquacer-exiu", exiu_dt_init);