1 files changed, 41 insertions, 0 deletions
diff --git a/kernel/lib/iommu-helper.c b/kernel/lib/iommu-helper.c
new file mode 100644
index 000000000..c27e26921
--- /dev/null
+++ b/kernel/lib/iommu-helper.c
@@ -0,0 +1,41 @@
+/*
+ * IOMMU helper functions for the free area management
+ */
+
+#include <linux/export.h>
+#include <linux/bitmap.h>
+#include <linux/bug.h>
+
+int iommu_is_span_boundary(unsigned int index, unsigned int nr,
+			   unsigned long shift,
+			   unsigned long boundary_size)
+{
+	BUG_ON(!is_power_of_2(boundary_size));
+
+	shift = (shift + index) & (boundary_size - 1);
+	return shift + nr > boundary_size;
+}
+
+unsigned long iommu_area_alloc(unsigned long *map, unsigned long size,
+			       unsigned long start, unsigned int nr,
+			       unsigned long shift, unsigned long boundary_size,
+			       unsigned long align_mask)
+{
+	unsigned long index;
+
+	/* We don't want the last of the limit */
+	size -= 1;
+again:
+	index = bitmap_find_next_zero_area(map, size, start, nr, align_mask);
+	if (index < size) {
+		if (iommu_is_span_boundary(index, nr, shift, boundary_size)) {
+			/* we could do more effectively */
+			start = index + 1;
+			goto again;
+		}
+		bitmap_set(map, index, nr);
+		return index;
+	}
+	return -1;
+}
+EXPORT_SYMBOL(iommu_area_alloc);