[PATCH 04/10] introduce generic iommu_num_pages function

[Joerg Roedel <joerg.roedel@amd.com>]

This patch introduces the generic iommu_num_pages function. It can be used by
different architectures to calculate the number of IOMMU pages required to map
a given memory area.

Signed-off-by: Joerg Roedel <joerg.roedel@amd.com>
---
 include/linux/iommu-helper.h |    2 ++
 lib/iommu-helper.c           |    9 +++++++++
 2 files changed, 11 insertions(+), 0 deletions(-)

diff --git a/include/linux/iommu-helper.h b/include/linux/iommu-helper.h
index c975caf..cb659aa 100644
--- a/include/linux/iommu-helper.h
+++ b/include/linux/iommu-helper.h
@@ -8,3 +8,5 @@ extern unsigned long iommu_area_alloc(unsigned long *map, unsigned long size,
 				      unsigned long align_mask);
 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);
diff --git a/lib/iommu-helper.c b/lib/iommu-helper.c
index a3b8d4c..ca4a963 100644
--- a/lib/iommu-helper.c
+++ b/lib/iommu-helper.c
@@ -80,3 +80,12 @@ 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);
-- 
1.5.3.7