v4.19.13 snapshot.
diff --git a/include/linux/of_iommu.h b/include/linux/of_iommu.h
new file mode 100644
index 0000000..f3d40dd
--- /dev/null
+++ b/include/linux/of_iommu.h
@@ -0,0 +1,35 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+#ifndef __OF_IOMMU_H
+#define __OF_IOMMU_H
+
+#include <linux/device.h>
+#include <linux/iommu.h>
+#include <linux/of.h>
+
+#ifdef CONFIG_OF_IOMMU
+
+extern int of_get_dma_window(struct device_node *dn, const char *prefix,
+ int index, unsigned long *busno, dma_addr_t *addr,
+ size_t *size);
+
+extern const struct iommu_ops *of_iommu_configure(struct device *dev,
+ struct device_node *master_np);
+
+#else
+
+static inline int of_get_dma_window(struct device_node *dn, const char *prefix,
+ int index, unsigned long *busno, dma_addr_t *addr,
+ size_t *size)
+{
+ return -EINVAL;
+}
+
+static inline const struct iommu_ops *of_iommu_configure(struct device *dev,
+ struct device_node *master_np)
+{
+ return NULL;
+}
+
+#endif /* CONFIG_OF_IOMMU */
+
+#endif /* __OF_IOMMU_H */