iommu sg: add IOMMU helper functions for the free area management

[mirror_ubuntu-artful-kernel.git] / lib / iommu-helper.c

diff --git a/lib/iommu-helper.c b/lib/iommu-helper.c
new file mode 100644 (file)
index 0000000..495575a
--- /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);