irqchip/loongson-pch-lpc: Add OF init code

The OF-based MIPS Loongson-3 systems can also have a PCH LPC interrupt
controller.

Add OF-based initialization code for this driver.

Co-developed-by: Jiaxun Yang <[e-mail]>
Signed-off-by: Jiaxun Yang <[e-mail]>
Signed-off-by: Icenowy Zheng <[e-mail]>
Signed-off-by: Thomas Gleixner <[e-mail]>
Reviewed-by: Huacai Chen <[e-mail]>
Link: https://patch.msgid.link/[e-mail]

drivers/irqchip/irq-loongson-pch-lpc.c

···
 #include <linux/irqchip/chained_irq.h>
 #include <linux/irqdomain.h>
 #include <linux/kernel.h>
+#include <linux/of_address.h>
+#include <linux/of_irq.h>
 #include <linux/syscore_ops.h>
 
 #include "irq-loongson.h"
···
 	return -ENOMEM;
 }
 
+#ifdef CONFIG_ACPI
 int __init pch_lpc_acpi_init(struct irq_domain *parent, struct acpi_madt_lpc_pic *acpi_pchlpc)
 {
 	struct fwnode_handle *irq_handle;
···
 
 	return 0;
 }
+#endif /* CONFIG_ACPI */
+
+#ifdef CONFIG_OF
+static int __init pch_lpc_of_init(struct device_node *node, struct device_node *parent)
+{
+	struct fwnode_handle *irq_handle;
+	struct resource res;
+	int parent_irq, ret;
+
+	if (of_address_to_resource(node, 0, &res))
+		return -EINVAL;
+
+	parent_irq = irq_of_parse_and_map(node, 0);
+	if (!parent_irq) {
+		pr_err("Failed to get the parent IRQ for LPC IRQs\n");
+		return -EINVAL;
+	}
+
+	irq_handle = of_fwnode_handle(node);
+
+	ret = pch_lpc_init(res.start, resource_size(&res), irq_handle,
+			   parent_irq);
+	if (ret) {
+		irq_dispose_mapping(parent_irq);
+		return ret;
+	}
+
+	return 0;
+}
+
+IRQCHIP_DECLARE(pch_lpc, "loongson,ls7a-lpc", pch_lpc_of_init);
+#endif /* CONFIG_OF */