device property: Add fwnode_iomap()

This patch introduces a new helper routine - fwnode_iomap(), which
allows to map the memory mapped IO for a given device node.

This implementation does not cover the ACPI case and may be expanded
in the future. The main purpose here is to be able to develop resource
provider agnostic drivers.
Suggested-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Signed-off-by: Anand Ashok Dumbre <anand.ashok.dumbre@xilinx.com>
Reviewed-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Acked-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Link: https://lore.kernel.org/r/20211203212358.31444-2-anand.ashok.dumbre@xilinx.comSigned-off-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>

drivers/base/property.c

@@ -958,6 +958,22 @@ int fwnode_irq_get(const struct fwnode_handle *fwnode, unsigned int index)
 }
 EXPORT_SYMBOL(fwnode_irq_get);
 
+/**
+ * fwnode_iomap - Maps the memory mapped IO for a given fwnode
+ * @fwnode:	Pointer to the firmware node
+ * @index:	Index of the IO range
+ *
+ * Returns a pointer to the mapped memory.
+ */
+void __iomem *fwnode_iomap(struct fwnode_handle *fwnode, int index)
+{
+	if (IS_ENABLED(CONFIG_OF_ADDRESS) && is_of_node(fwnode))
+		return of_iomap(to_of_node(fwnode), index);
+
+	return NULL;
+}
+EXPORT_SYMBOL(fwnode_iomap);
+
 /**
  * fwnode_graph_get_next_endpoint - Get next endpoint firmware node
  * @fwnode: Pointer to the parent firmware node

include/linux/property.h

@@ -122,6 +122,8 @@ void fwnode_handle_put(struct fwnode_handle *fwnode);
 
 int fwnode_irq_get(const struct fwnode_handle *fwnode, unsigned int index);
 
+void __iomem *fwnode_iomap(struct fwnode_handle *fwnode, int index);
+
 unsigned int device_get_child_node_count(struct device *dev);
 
 static inline bool device_property_read_bool(struct device *dev,