1 files changed, 107 insertions, 0 deletions

diff --git a/drivers/of/irq.c b/drivers/of/irq.c
index 6a5b5e777dd2..6d3dd3988d0f 100644
--- a/drivers/of/irq.c
+++ b/drivers/of/irq.c
@@ -19,10 +19,12 @@
  */
 
 #include <linux/errno.h>
+#include <linux/list.h>
 #include <linux/module.h>
 #include <linux/of.h>
 #include <linux/of_irq.h>
 #include <linux/string.h>
+#include <linux/slab.h>
 
 /* For archs that don't support NO_IRQ (such as x86), provide a dummy value */
 #ifndef NO_IRQ
@@ -386,3 +388,108 @@ int of_irq_to_resource_table(struct device_node *dev, struct resource *res,
 
 	return i;
 }
+
+struct intc_desc {
+	struct list_head	list;
+	struct device_node	*dev;
+	struct device_node	*interrupt_parent;
+};
+
+/**
+ * of_irq_init - Scan and init matching interrupt controllers in DT
+ * @matches: 0 terminated array of nodes to match and init function to call
+ *
+ * This function scans the device tree for matching interrupt controller nodes,
+ * and calls their initialization functions in order with parents first.
+ */
+void __init of_irq_init(const struct of_device_id *matches)
+{
+	struct device_node *np, *parent = NULL;
+	struct intc_desc *desc, *temp_desc;
+	struct list_head intc_desc_list, intc_parent_list;
+
+	INIT_LIST_HEAD(&intc_desc_list);
+	INIT_LIST_HEAD(&intc_parent_list);
+
+	for_each_matching_node(np, matches) {
+		if (!of_find_property(np, "interrupt-controller", NULL))
+			continue;
+		/*
+		 * Here, we allocate and populate an intc_desc with the node
+		 * pointer, interrupt-parent device_node etc.
+		 */
+		desc = kzalloc(sizeof(*desc), GFP_KERNEL);
+		if (WARN_ON(!desc))
+			goto err;
+
+		desc->dev = np;
+		desc->interrupt_parent = of_irq_find_parent(np);
+		list_add_tail(&desc->list, &intc_desc_list);
+	}
+
+	/*
+	 * The root irq controller is the one without an interrupt-parent.
+	 * That one goes first, followed by the controllers that reference it,
+	 * followed by the ones that reference the 2nd level controllers, etc.
+	 */
+	while (!list_empty(&intc_desc_list)) {
+		/*
+		 * Process all controllers with the current 'parent'.
+		 * First pass will be looking for NULL as the parent.
+		 * The assumption is that NULL parent means a root controller.
+		 */
+		list_for_each_entry_safe(desc, temp_desc, &intc_desc_list, list) {
+			const struct of_device_id *match;
+			int ret;
+			of_irq_init_cb_t irq_init_cb;
+
+			if (desc->interrupt_parent != parent)
+				continue;
+
+			list_del(&desc->list);
+			match = of_match_node(matches, desc->dev);
+			if (WARN(!match->data,
+			    "of_irq_init: no init function for %s\n",
+			    match->compatible)) {
+				kfree(desc);
+				continue;
+			}
+
+			pr_debug("of_irq_init: init %s @ %p, parent %p\n",
+				 match->compatible,
+				 desc->dev, desc->interrupt_parent);
+			irq_init_cb = match->data;
+			ret = irq_init_cb(desc->dev, desc->interrupt_parent);
+			if (ret) {
+				kfree(desc);
+				continue;
+			}
+
+			/*
+			 * This one is now set up; add it to the parent list so
+			 * its children can get processed in a subsequent pass.
+			 */
+			list_add_tail(&desc->list, &intc_parent_list);
+		}
+
+		/* Get the next pending parent that might have children */
+		desc = list_first_entry(&intc_parent_list, typeof(*desc), list);
+		if (list_empty(&intc_parent_list) || !desc) {
+			pr_err("of_irq_init: children remain, but no parents\n");
+			break;
+		}
+		list_del(&desc->list);
+		parent = desc->dev;
+		kfree(desc);
+	}
+
+	list_for_each_entry_safe(desc, temp_desc, &intc_parent_list, list) {
+		list_del(&desc->list);
+		kfree(desc);
+	}
+err:
+	list_for_each_entry_safe(desc, temp_desc, &intc_desc_list, list) {
+		list_del(&desc->list);
+		kfree(desc);
+	}
+}