[PATCH 1/3] add iommu_device_max_index IOMMU helper function

[FUJITA Tomonori]

This function helps IOMMUs to know the highest address that a device
can access to.

Signed-off-by: FUJITA Tomonori <fujita.tomonori@xxxxxxxxxxxxx>
---
 include/linux/iommu-helper.h |   10 ++++++++++
 1 files changed, 10 insertions(+), 0 deletions(-)

diff --git a/include/linux/iommu-helper.h b/include/linux/iommu-helper.h
index c975caf..58f4110 100644
--- a/include/linux/iommu-helper.h
+++ b/include/linux/iommu-helper.h
@@ -1,3 +1,13 @@
+static inline unsigned long iommu_device_max_index(unsigned long size,
+						   unsigned long offset,
+						   u64 dma_mask)
+{
+	if (size + offset > dma_mask)
+		return dma_mask - offset + 1;
+	else
+		return size;
+}
+
 extern int iommu_is_span_boundary(unsigned int index, unsigned int nr,
 				  unsigned long shift,
 				  unsigned long boundary_size);
-- 
1.5.5.GIT

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