[POWERPC] add of_iomap function

The of_iomap function maps memory for a given
device_node and returns a pointer to that memory.
This is used at some places, so it makes sense to
a seperate function.

Signed-off-by: Christian Krafft <krafft@de.ibm.com>
Signed-off-by: Arnd Bergmann <arnd.bergmann@de.ibm.com>
diff --git a/include/asm-powerpc/prom.h b/include/asm-powerpc/prom.h
index e73a2b4..f31af71 100644
--- a/include/asm-powerpc/prom.h
+++ b/include/asm-powerpc/prom.h
@@ -20,6 +20,7 @@
 #include <linux/platform_device.h>
 #include <asm/irq.h>
 #include <asm/atomic.h>
+#include <asm/io.h>
 
 /* Definitions used by the flattened device tree */
 #define OF_DT_HEADER		0xd00dfeed	/* marker */
@@ -355,6 +356,16 @@
 	return irq;
 }
 
+static inline void __iomem *of_iomap(struct device_node *np, int index)
+{
+	struct resource res;
+
+	if (of_address_to_resource(np, index, &res))
+		return NULL;
+
+	return ioremap(res.start, 1 + res.end - res.start);
+}
+
 
 #endif /* __KERNEL__ */
 #endif /* _POWERPC_PROM_H */