--- /dev/null
+From 0a957467c5fd46142bc9c52758ffc552d4c5e2f7 Mon Sep 17 00:00:00 2001
+From: Guenter Roeck <linux@roeck-us.net>
+Date: Wed, 15 Aug 2018 13:22:27 -0700
+Subject: x86: i8259: Add missing include file
+
+From: Guenter Roeck <linux@roeck-us.net>
+
+commit 0a957467c5fd46142bc9c52758ffc552d4c5e2f7 upstream.
+
+i8259.h uses inb/outb and thus needs to include asm/io.h to avoid the
+following build error, as seen with x86_64:defconfig and CONFIG_SMP=n.
+
+ In file included from drivers/rtc/rtc-cmos.c:45:0:
+ arch/x86/include/asm/i8259.h: In function 'inb_pic':
+ arch/x86/include/asm/i8259.h:32:24: error:
+ implicit declaration of function 'inb'
+
+ arch/x86/include/asm/i8259.h: In function 'outb_pic':
+ arch/x86/include/asm/i8259.h:45:2: error:
+ implicit declaration of function 'outb'
+
+Reported-by: Sebastian Gottschall <s.gottschall@dd-wrt.com>
+Suggested-by: Sebastian Gottschall <s.gottschall@dd-wrt.com>
+Fixes: 447ae3166702 ("x86: Don't include linux/irq.h from asm/hardirq.h")
+Signed-off-by: Guenter Roeck <linux@roeck-us.net>
+Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
+Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
+
+---
+ arch/x86/include/asm/i8259.h | 1 +
+ 1 file changed, 1 insertion(+)
+
+--- a/arch/x86/include/asm/i8259.h
++++ b/arch/x86/include/asm/i8259.h
+@@ -3,6 +3,7 @@
+ #define _ASM_X86_I8259_H
+
+ #include <linux/delay.h>
++#include <asm/io.h>
+
+ extern unsigned int cached_irq_mask;
+