diff --git a/include/asm-generic/io.h b/include/asm-generic/io.h
index e93375c..cc7338f 100644
--- a/include/asm-generic/io.h
+++ b/include/asm-generic/io.h
@@ -1023,16 +1023,7 @@
 	port &= IO_SPACE_LIMIT;
 	return (port > MMIO_UPPER_LIMIT) ? NULL : PCI_IOBASE + port;
 }
-#define __pci_ioport_unmap __pci_ioport_unmap
-static inline void __pci_ioport_unmap(void __iomem *p)
-{
-	uintptr_t start = (uintptr_t) PCI_IOBASE;
-	uintptr_t addr = (uintptr_t) p;
-
-	if (addr >= start && addr < start + IO_SPACE_LIMIT)
-		return;
-	iounmap(p);
-}
+#define ARCH_HAS_GENERIC_IOPORT_MAP
 #endif
 
 #ifndef ioport_unmap
@@ -1048,21 +1039,10 @@
 #endif /* CONFIG_HAS_IOPORT_MAP */
 
 #ifndef CONFIG_GENERIC_IOMAP
-struct pci_dev;
-extern void __iomem *pci_iomap(struct pci_dev *dev, int bar, unsigned long max);
-
-#ifndef __pci_ioport_unmap
-static inline void __pci_ioport_unmap(void __iomem *p) {}
-#endif
-
 #ifndef pci_iounmap
-#define pci_iounmap pci_iounmap
-static inline void pci_iounmap(struct pci_dev *dev, void __iomem *p)
-{
-	__pci_ioport_unmap(p);
-}
+#define ARCH_WANTS_GENERIC_PCI_IOUNMAP
 #endif
-#endif /* CONFIG_GENERIC_IOMAP */
+#endif
 
 #ifndef xlate_dev_mem_ptr
 #define xlate_dev_mem_ptr xlate_dev_mem_ptr
diff --git a/lib/pci_iomap.c b/lib/pci_iomap.c
index 2d3eb1c..ce39ce9 100644
--- a/lib/pci_iomap.c
+++ b/lib/pci_iomap.c
@@ -134,4 +134,47 @@
 	return pci_iomap_wc_range(dev, bar, 0, maxlen);
 }
 EXPORT_SYMBOL_GPL(pci_iomap_wc);
+
+/*
+ * pci_iounmap() somewhat illogically comes from lib/iomap.c for the
+ * CONFIG_GENERIC_IOMAP case, because that's the code that knows about
+ * the different IOMAP ranges.
+ *
+ * But if the architecture does not use the generic iomap code, and if
+ * it has _not_ defined it's own private pci_iounmap function, we define
+ * it here.
+ *
+ * NOTE! This default implementation assumes that if the architecture
+ * support ioport mapping (HAS_IOPORT_MAP), the ioport mapping will
+ * be fixed to the range [ PCI_IOBASE, PCI_IOBASE+IO_SPACE_LIMIT [,
+ * and does not need unmapping with 'ioport_unmap()'.
+ *
+ * If you have different rules for your architecture, you need to
+ * implement your own pci_iounmap() that knows the rules for where
+ * and how IO vs MEM get mapped.
+ *
+ * This code is odd, and the ARCH_HAS/ARCH_WANTS #define logic comes
+ * from legacy <asm-generic/io.h> header file behavior. In particular,
+ * it would seem to make sense to do the iounmap(p) for the non-IO-space
+ * case here regardless, but that's not what the old header file code
+ * did. Probably incorrectly, but this is meant to be bug-for-bug
+ * compatible.
+ */
+#if defined(ARCH_WANTS_GENERIC_PCI_IOUNMAP)
+
+void pci_iounmap(struct pci_dev *dev, void __iomem *p)
+{
+#ifdef ARCH_HAS_GENERIC_IOPORT_MAP
+	uintptr_t start = (uintptr_t) PCI_IOBASE;
+	uintptr_t addr = (uintptr_t) p;
+
+	if (addr >= start && addr < start + IO_SPACE_LIMIT)
+		return;
+	iounmap(p);
+#endif
+}
+EXPORT_SYMBOL(pci_iounmap);
+
+#endif /* ARCH_WANTS_GENERIC_PCI_IOUNMAP */
+
 #endif /* CONFIG_PCI */