3 files changed, 88 insertions, 0 deletions

diff --git a/include/linux/iommu-helper.h b/include/linux/iommu-helper.h
new file mode 100644
index 000000000000..4dd4c04ff2f4
--- /dev/null
+++ b/include/linux/iommu-helper.h
@@ -0,0 +1,7 @@
+extern 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);
+extern void iommu_area_free(unsigned long *map, unsigned long start,
+                            unsigned int nr);
diff --git a/lib/Makefile b/lib/Makefile
index 543f2502b60a..a18062e4633f 100644
--- a/lib/Makefile
+++ b/lib/Makefile
@@ -65,6 +65,7 @@ obj-$(CONFIG_SMP) += pcounter.o
 obj-$(CONFIG_AUDIT_GENERIC) += audit.o
 
 obj-$(CONFIG_SWIOTLB) += swiotlb.o
+obj-$(CONFIG_IOMMU_HELPER) += iommu-helper.o
 obj-$(CONFIG_FAULT_INJECTION) += fault-inject.o
 
 lib-$(CONFIG_GENERIC_BUG) += bug.o
diff --git a/lib/iommu-helper.c b/lib/iommu-helper.c
new file mode 100644
index 000000000000..495575a59ca6
--- /dev/null
+++ b/lib/iommu-helper.c
@@ -0,0 +1,80 @@
+/*
+ * IOMMU helper functions for the free area management
+ */
+
+#include <linux/module.h>
+#include <linux/bitops.h>
+
+static unsigned long find_next_zero_area(unsigned long *map,
+                                         unsigned long size,
+                                         unsigned long start,
+                                         unsigned int nr,
+                                         unsigned long align_mask)
+{
+        unsigned long index, end, i;
+again:
+        index = find_next_zero_bit(map, size, start);
+
+        /* Align allocation */
+        index = (index + align_mask) & ~align_mask;
+
+        end = index + nr;
+        if (end >= size)
+                return -1;
+        for (i = index; i < end; i++) {
+                if (test_bit(i, map)) {
+                        start = i+1;
+                        goto again;
+                }
+        }
+        return index;
+}
+
+static inline void set_bit_area(unsigned long *map, unsigned long i,
+                                int len)
+{
+        unsigned long end = i + len;
+        while (i < end) {
+                __set_bit(i, map);
+                i++;
+        }
+}
+
+static inline int is_span_boundary(unsigned int index, unsigned int nr,
+                                   unsigned long shift,
+                                   unsigned long 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;
+again:
+        index = find_next_zero_area(map, size, start, nr, align_mask);
+        if (index != -1) {
+                if (is_span_boundary(index, nr, shift, boundary_size)) {
+                        /* we could do more effectively */
+                        start = index + 1;
+                        goto again;
+                }
+                set_bit_area(map, index, nr);
+        }
+        return index;
+}
+EXPORT_SYMBOL(iommu_area_alloc);
+
+void iommu_area_free(unsigned long *map, unsigned long start, unsigned int nr)
+{
+        unsigned long end = start + nr;
+
+        while (start < end) {
+                __clear_bit(start, map);
+                start++;
+        }
+}
+EXPORT_SYMBOL(iommu_area_free);