diff --git a/arch/ia64/Kconfig b/arch/ia64/Kconfig
index 3aa6c821449a90fd43d0169fb3bbcf410140602d..07f5d353b54ab070b32ee8019c0c0ba48f438399 100644
--- a/arch/ia64/Kconfig
+++ b/arch/ia64/Kconfig
@@ -47,6 +47,9 @@ config MMU
 config SWIOTLB
        bool
 
+config IOMMU_HELPER
+       bool
+
 config GENERIC_LOCKBREAK
 	bool
 	default y
@@ -615,7 +618,7 @@ config IRQ_PER_CPU
 	default y
 
 config IOMMU_HELPER
-	def_bool (IA64_HP_ZX1 || IA64_HP_ZX1_SWIOTLB || IA64_GENERIC)
+	def_bool (IA64_HP_ZX1 || IA64_HP_ZX1_SWIOTLB || IA64_GENERIC || SWIOTLB)
 
 source "arch/ia64/hp/sim/Kconfig"
 
diff --git a/arch/x86/Kconfig b/arch/x86/Kconfig
index a12dbb2b93f381066a34ec0ff57e5ff753ba29b5..1d9d874cba59f94bb3bd412dc1bb53a6d94bd7d5 100644
--- a/arch/x86/Kconfig
+++ b/arch/x86/Kconfig
@@ -537,9 +537,6 @@ config CALGARY_IOMMU_ENABLED_BY_DEFAULT
 	  Calgary anyway, pass 'iommu=calgary' on the kernel command line.
 	  If unsure, say Y.
 
-config IOMMU_HELPER
-	def_bool (CALGARY_IOMMU || GART_IOMMU)
-
 # need this always selected by IOMMU for the VIA workaround
 config SWIOTLB
 	bool
@@ -550,6 +547,8 @@ config SWIOTLB
 	  access 32-bits of memory can be used on systems with more than
 	  3 GB of memory. If unsure, say Y.
 
+config IOMMU_HELPER
+	def_bool (CALGARY_IOMMU || GART_IOMMU || SWIOTLB)
 
 config NR_CPUS
 	int "Maximum number of CPUs (2-255)"
diff --git a/lib/swiotlb.c b/lib/swiotlb.c
index 256c8445e54dccaf8697d201a32874d19ca31499..3c95922e51e7caaf4bb7a5014d58fba4778580df 100644
--- a/lib/swiotlb.c
+++ b/lib/swiotlb.c
@@ -31,6 +31,7 @@
 
 #include <linux/init.h>
 #include <linux/bootmem.h>
+#include <linux/iommu-helper.h>
 
 #define OFFSET(val,align) ((unsigned long)	\
 	                   ( (val) & ( (align) - 1)))
@@ -282,15 +283,6 @@ address_needs_mapping(struct device *hwdev, dma_addr_t addr)
 	return (addr & ~mask) != 0;
 }
 
-static inline unsigned int is_span_boundary(unsigned int index,
-					    unsigned int nslots,
-					    unsigned long offset_slots,
-					    unsigned long max_slots)
-{
-	unsigned long offset = (offset_slots + index) & (max_slots - 1);
-	return offset + nslots > max_slots;
-}
-
 /*
  * Allocates bounce buffer and returns its kernel virtual address.
  */
@@ -337,8 +329,8 @@ map_single(struct device *hwdev, char *buffer, size_t size, int dir)
 	wrap = index;
 
 	do {
-		while (is_span_boundary(index, nslots, offset_slots,
-				max_slots)) {
+		while (iommu_is_span_boundary(index, nslots, offset_slots,
+					      max_slots)) {
 			index += stride;
 			if (index >= io_tlb_nslabs)
 				index = 0;