iommu: export iommu_is_span_boundary helper function

iommu_is_span_boundary is used internally in the IOMMU helper
(lib/iommu-helper.c), a primitive function that judges whether a memory area
spans LLD's segment boundary or not.

It's difficult to convert some IOMMUs to use the IOMMU helper but
iommu_is_span_boundary is still useful for them.  So this patch exports it.

This is needed for the parisc iommu fixes.

Signed-off-by: FUJITA Tomonori <fujita.tomonori@lab.ntt.co.jp>
Cc: Kyle McMartin <kyle@parisc-linux.org>
Cc: Matthew Wilcox <matthew@wil.cx>
Cc: Grant Grundler <grundler@parisc-linux.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

diff --git a/include/linux/iommu-helper.h b/include/linux/iommu-helper.h
index 4dd4c04..c975caf 100644 (file)
--- a/include/linux/iommu-helper.h
+++ b/include/linux/iommu-helper.h
@@ -1,3 +1,6 @@
+extern int iommu_is_span_boundary(unsigned int index, unsigned int nr,
+                                 unsigned long shift,
+                                 unsigned long boundary_size);
 extern unsigned long iommu_area_alloc(unsigned long *map, unsigned long size,
                                      unsigned long start, unsigned int nr,
                                      unsigned long shift,

diff --git a/lib/iommu-helper.c b/lib/iommu-helper.c
index 495575a..a3b8d4c 100644 (file)
--- a/lib/iommu-helper.c
+++ b/lib/iommu-helper.c
@@ -40,10 +40,12 @@ static inline void set_bit_area(unsigned long *map, unsigned long i,
        }
 }
 
-static inline int is_span_boundary(unsigned int index, unsigned int nr,
-                                  unsigned long shift,
-                                  unsigned long boundary_size)
+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;
 }
@@ -57,7 +59,7 @@ unsigned long iommu_area_alloc(unsigned long *map, unsigned long size,
 again:
        index = find_next_zero_area(map, size, start, nr, align_mask);
        if (index != -1) {
-               if (is_span_boundary(index, nr, shift, boundary_size)) {
+               if (iommu_is_span_boundary(index, nr, shift, boundary_size)) {
                        /* we could do more effectively */
                        start = index + 1;
                        goto again;