+#ifndef _LINUX_IOMMU_HELPER_H
+#define _LINUX_IOMMU_HELPER_H
+
+static inline unsigned long iommu_device_max_index(unsigned long size,
+ unsigned long offset,
+ u64 dma_mask)
+{
+ if (size + offset > dma_mask)
+ return dma_mask - offset + 1;
+ else
+ return size;
+}
+