v4.19.13 snapshot.
diff --git a/arch/um/include/asm/io.h b/arch/um/include/asm/io.h
new file mode 100644
index 0000000..96f77b5
--- /dev/null
+++ b/arch/um/include/asm/io.h
@@ -0,0 +1,18 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+#ifndef _ASM_UM_IO_H
+#define _ASM_UM_IO_H
+
+#define ioremap ioremap
+static inline void __iomem *ioremap(phys_addr_t offset, size_t size)
+{
+ return (void __iomem *)(unsigned long)offset;
+}
+
+#define iounmap iounmap
+static inline void iounmap(void __iomem *addr)
+{
+}
+
+#include <asm-generic/io.h>
+
+#endif