diff --git a/tests/mmio.h b/tests/mmio.h
index b887b2b5..c37bff07 100644
--- a/tests/mmio.h
+++ b/tests/mmio.h
@@ -3,6 +3,30 @@
 
 #include <stdint.h>
 
+static inline void reg_write8(uintptr_t addr, uint8_t data)
+{
+	volatile uint8_t *ptr = (volatile uint8_t *) addr;
+	*ptr = data;
+}
+
+static inline uint8_t reg_read8(uintptr_t addr)
+{
+	volatile uint8_t *ptr = (volatile uint8_t *) addr;
+	return *ptr;
+}
+
+static inline void reg_write16(uintptr_t addr, uint16_t data)
+{
+	volatile uint16_t *ptr = (volatile uint16_t *) addr;
+	*ptr = data;
+}
+
+static inline uint16_t reg_read16(uintptr_t addr)
+{
+	volatile uint16_t *ptr = (volatile uint16_t *) addr;
+	return *ptr;
+}
+
 static inline void reg_write32(uintptr_t addr, uint32_t data)
 {
 	volatile uint32_t *ptr = (volatile uint32_t *) addr;