[PATCH] add iommu_num_pages helper function

[Joerg Roedel]

Calculating the number of pages from given address and length numbers is a task
required in multiple IOMMU implementations. So implement this as a generic
function into the IOMMU helper code.

Cc: FUJITA Tomonori <fujita.tomonori@xxxxxxxxxxxxx>
Signed-off-by: Joerg Roedel <joerg.roedel@xxxxxxx>
---
 include/linux/iommu-helper.h |    1 +
 lib/iommu-helper.c           |    8 ++++++++
 2 files changed, 9 insertions(+), 0 deletions(-)

diff --git a/include/linux/iommu-helper.h b/include/linux/iommu-helper.h
index c975caf..f8598f5 100644
--- a/include/linux/iommu-helper.h
+++ b/include/linux/iommu-helper.h
@@ -8,3 +8,4 @@ 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);
diff --git a/lib/iommu-helper.c b/lib/iommu-helper.c
index a3b8d4c..889ddce 100644
--- a/lib/iommu-helper.c
+++ b/lib/iommu-helper.c
@@ -80,3 +80,11 @@ 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 size = roundup((addr & ~PAGE_MASK) + len, PAGE_SIZE);
+
+	return size >> PAGE_SHIFT;
+}
+EXPORT_SYMBOL(iommu_num_pages);
-- 
1.5.3.7


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