iommu sg merging: PCI: add dma segment boundary support

This adds PCI's accessor for segment_boundary_mask in device_dma_parameters.

The default segment_boundary is set to 0xffffffff, same to the block layer's
default value (and the scsi mid layer uses the same value).

Signed-off-by: FUJITA Tomonori <fujita.tomonori@lab.ntt.co.jp>
Cc: James Bottomley <James.Bottomley@steeleye.com>
Cc: Jens Axboe <jens.axboe@oracle.com>
Cc: Greg KH <greg@kroah.com>
Cc: Jeff Garzik <jeff@garzik.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
diff --git a/include/linux/pci.h b/include/linux/pci.h
index ba3a7f4..7215d3b 100644
--- a/include/linux/pci.h
+++ b/include/linux/pci.h
@@ -583,6 +583,7 @@
 int pci_set_dma_mask(struct pci_dev *dev, u64 mask);
 int pci_set_consistent_dma_mask(struct pci_dev *dev, u64 mask);
 int pci_set_dma_max_seg_size(struct pci_dev *dev, unsigned int size);
+int pci_set_dma_seg_boundary(struct pci_dev *dev, unsigned long mask);
 int pcix_get_max_mmrbc(struct pci_dev *dev);
 int pcix_get_mmrbc(struct pci_dev *dev);
 int pcix_set_mmrbc(struct pci_dev *dev, int mmrbc);
@@ -831,6 +832,12 @@
 	return -EIO;
 }
 
+static inline int pci_set_dma_seg_boundary(struct pci_dev *dev,
+					unsigned long mask)
+{
+	return -EIO;
+}
+
 static inline int pci_assign_resource(struct pci_dev *dev, int i)
 {
 	return -EBUSY;