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-rw-r--r--include/linux/iommu-helper.h3
-rw-r--r--lib/iommu-helper.c9
2 files changed, 12 insertions, 0 deletions
diff --git a/include/linux/iommu-helper.h b/include/linux/iommu-helper.h
index a6d0586e2bf..3b068e5b567 100644
--- a/include/linux/iommu-helper.h
+++ b/include/linux/iommu-helper.h
@@ -23,4 +23,7 @@ extern unsigned long iommu_area_alloc(unsigned long *map, unsigned long size,
extern void iommu_area_free(unsigned long *map, unsigned long start,
unsigned int nr);
+extern unsigned long iommu_num_pages(unsigned long addr, unsigned long len,
+ unsigned long io_page_size);
+
#endif
diff --git a/lib/iommu-helper.c b/lib/iommu-helper.c
index 5d90074dca7..75dbda03f4f 100644
--- a/lib/iommu-helper.c
+++ b/lib/iommu-helper.c
@@ -79,3 +79,12 @@ void iommu_area_free(unsigned long *map, unsigned long start, unsigned int nr)
}
}
EXPORT_SYMBOL(iommu_area_free);
+
+unsigned long iommu_num_pages(unsigned long addr, unsigned long len,
+ unsigned long io_page_size)
+{
+ unsigned long size = (addr & (io_page_size - 1)) + len;
+
+ return DIV_ROUND_UP(size, io_page_size);
+}
+EXPORT_SYMBOL(iommu_num_pages);