[RFC PATCH 2/4] of/address: Add of_find_matching_node_by_address helper

[Grant Likely]

of_find_matching_node_by_address() can be used to find a device tree
node for a device at a specific address.

Signed-off-by: Grant Likely <grant.likely at secretlab.ca>
---
 drivers/of/address.c       |   18 ++++++++++++++++++
 include/linux/of_address.h |    4 ++++
 2 files changed, 22 insertions(+), 0 deletions(-)

diff --git a/drivers/of/address.c b/drivers/of/address.c
index b43ff66..deefc0c 100644
--- a/drivers/of/address.c
+++ b/drivers/of/address.c
@@ -591,6 +591,24 @@ int of_address_to_resource(struct device_node *dev, int index,
 }
 EXPORT_SYMBOL_GPL(of_address_to_resource);
 
+struct device_node *of_find_matching_node_by_address(struct device_node *from,
+					const struct of_device_id *matches,
+					u64 base_address)
+{
+	struct device_node *dn = of_find_matching_node(from, matches);
+	struct resource res;
+
+	while (dn) {
+		if (of_address_to_resource(dn, 0, &res))
+			continue;
+		if (res.start == base_address)
+			return dn;
+		dn = of_find_matching_node(dn, matches);
+	}
+
+	return NULL;
+}
+
 
 /**
  * of_iomap - Maps the memory mapped IO for a given device_node
diff --git a/include/linux/of_address.h b/include/linux/of_address.h
index 6711d5f..4fbea28 100644
--- a/include/linux/of_address.h
+++ b/include/linux/of_address.h
@@ -7,6 +7,10 @@ extern int of_address_count(struct device_node *np);
 extern u64 of_translate_address(struct device_node *np, const __be32 *addr);
 extern int of_address_to_resource(struct device_node *dev, int index,
 				  struct resource *r);
+extern struct device_node *of_find_matching_node_by_address(
+					struct device_node *from,
+					const struct of_device_id *matches,
+					u64 base_address);
 extern void __iomem *of_iomap(struct device_node *device, int index);
 
 /* Extract an address from a device, returns the region size and