diff --git a/include/asm-generic/gpio.h b/include/asm-generic/gpio.h
index 81f63f0..0fcf709 100644
--- a/include/asm-generic/gpio.h
+++ b/include/asm-generic/gpio.h
@@ -127,6 +127,7 @@
 #define GPIOD_OPEN_SOURCE	BIT(6)	/* GPIO is open source type */
 #define GPIOD_PULL_UP		BIT(7)	/* GPIO has pull-up enabled */
 #define GPIOD_PULL_DOWN		BIT(8)	/* GPIO has pull-down enabled */
+#define GPIOD_IS_AF		BIT(9)	/* GPIO is an alternate function */
 
 /* Flags for updating the above */
 #define GPIOD_MASK_DIR		(GPIOD_IS_OUT | GPIOD_IS_IN | \
diff --git a/include/dt-bindings/gpio/sandbox-gpio.h b/include/dt-bindings/gpio/sandbox-gpio.h
index e4bfdb3..05f9836 100644
--- a/include/dt-bindings/gpio/sandbox-gpio.h
+++ b/include/dt-bindings/gpio/sandbox-gpio.h
@@ -21,4 +21,7 @@
 /* Bit 18 express GPIO output is active */
 #define GPIO_OUT_ACTIVE		0x40000
 
+/* Bit 19 express GPIO set as alternate function */
+#define GPIO_AF			0x80000
+
 #endif