irqchip: atmel-aic: Add irq fixup infrastructure

Add irq fixup infrastructure to handle IP blocks connected to shared irqs
that are left in an unknown state when booting the kernel.

In this case the IP block which has not masked its interrupt and has no
driver loaded (either because it is not compiled or because it is not
loaded yet) might generate spurious interrupts when another IP block
request the shared irq.

A good example of this case is the RTC block on which register configs are
kept even after a shutdown (if a proper VDDcore is supplied), and thus
might generate spurious interrupts when the platform is switched on.

Signed-off-by: Boris BREZILLON <boris.brezillon@free-electrons.com>
Link: https://lkml.kernel.org/r/1405016741-2407-2-git-send-email-boris.brezillon@free-electrons.com
Signed-off-by: Jason Cooper <jason@lakedaemon.net>

drivers/irqchip/irq-atmel-aic-common.c

@@ -139,6 +139,25 @@ static void __init aic_common_ext_irq_of_init(struct irq_domain *domain)
 	}
 }
 
+void __init aic_common_irq_fixup(const struct of_device_id *matches)
+{
+	struct device_node *root = of_find_node_by_path("/");
+	const struct of_device_id *match;
+
+	if (!root)
+		return;
+
+	match = of_match_node(matches, root);
+	of_node_put(root);
+
+	if (match) {
+		void (*fixup)(struct device_node *) = match->data;
+		fixup(root);
+	}
+
+	of_node_put(root);
+}
+
 struct irq_domain *__init aic_common_of_init(struct device_node *node,
 					     const struct irq_domain_ops *ops,
 					     const char *name, int nirqs)

drivers/irqchip/irq-atmel-aic-common.h

@@ -32,4 +32,6 @@ struct irq_domain *__init aic_common_of_init(struct device_node *node,
 					     const struct irq_domain_ops *ops,
 					     const char *name, int nirqs);
 
+void __init aic_common_irq_fixup(const struct of_device_id *matches);
+
 #endif /* __IRQ_ATMEL_AIC_COMMON_H */