of: Add support for reading a u32 from a multi-value property.

This patch adds an of_property_read_u32_index() function to allow
reading a single indexed u32 value from a property containing multiple
u32 values.

Signed-off-by: Tony Prisk <linux@prisktech.co.nz>
Reviewed-by: Stephen Warren <swarren@nvidia.com>
Acked-by: Linus Walleij <linus.walleij@linaro.org>
Acked-by: Rob Herring <robherring2@gmail.com>
diff --git a/include/linux/of.h b/include/linux/of.h
index a0f1292..c0747a4 100644
--- a/include/linux/of.h
+++ b/include/linux/of.h
@@ -235,6 +235,9 @@
 extern struct property *of_find_property(const struct device_node *np,
 					 const char *name,
 					 int *lenp);
+extern int of_property_read_u32_index(const struct device_node *np,
+				       const char *propname,
+				       u32 index, u32 *out_value);
 extern int of_property_read_u8_array(const struct device_node *np,
 			const char *propname, u8 *out_values, size_t sz);
 extern int of_property_read_u16_array(const struct device_node *np,
@@ -394,6 +397,12 @@
 	return NULL;
 }
 
+static inline int of_property_read_u32_index(const struct device_node *np,
+			const char *propname, u32 index, u32 *out_value)
+{
+	return -ENOSYS;
+}
+
 static inline int of_property_read_u8_array(const struct device_node *np,
 			const char *propname, u8 *out_values, size_t sz)
 {