5 files changed, 9 insertions, 7 deletions
diff --git a/libmaple/i2c.h b/libmaple/i2c.h
index 21c17c1..a17e144 100644
--- a/libmaple/i2c.h
+++ b/libmaple/i2c.h
@@ -66,7 +66,7 @@ typedef struct i2c_dev {
     uint8 clk_line;
     uint8 ev_nvic_line;
     uint8 er_nvic_line;
-    volatile uint8 state;
+    __io uint8 state;
     uint16 msgs_left;
     i2c_msg *msg;
 } i2c_dev;
diff --git a/libmaple/ring_buffer.h b/libmaple/ring_buffer.h
index ad6ad96..04f6499 100644
--- a/libmaple/ring_buffer.h
+++ b/libmaple/ring_buffer.h
@@ -35,6 +35,8 @@
 #ifndef _RING_BUFFER_H_
 #define _RING_BUFFER_H_
 
+#include "libmaple_types.h"
+
 #ifdef __cplusplus
 extern "C"{
 #endif
@@ -49,7 +51,7 @@ extern "C"{
  *
  * One byte is left free to distinguish empty from full. */
 typedef struct ring_buffer {
-    volatile uint8 *buf; /**< Buffer items are stored into */
+    __io uint8 *buf;     /**< Buffer items are stored into */
     uint16 head;         /**< Index of the next item to remove */
     uint16 tail;         /**< Index where the next item will get inserted */
     uint16 size;         /**< Buffer capacity minus one */
@@ -79,7 +81,7 @@ static inline void rb_init(ring_buffer *rb, uint16 size, uint8 *buf) {
  * @param rb Buffer whose elements to count.
  */
 static inline uint16 rb_full_count(ring_buffer *rb) {
-    volatile ring_buffer *arb = rb;
+    __io ring_buffer *arb = rb;
     int32 size = arb->tail - arb->head;
     if (arb->tail < arb->head) {
         size += arb->size + 1;
diff --git a/libmaple/systick.c b/libmaple/systick.c
index c04f4f3..103893e 100644
--- a/libmaple/systick.c
+++ b/libmaple/systick.c
@@ -28,7 +28,7 @@
 
 #include "systick.h"
 
-volatile uint32 systick_timer_millis;
+__io uint32 systick_timer_millis;
 
 /**
  * @brief Initialize and enable SysTick.
diff --git a/libmaple/systick.h b/libmaple/systick.h
index 35b4cb9..4654c5f 100644
--- a/libmaple/systick.h
+++ b/libmaple/systick.h
@@ -73,7 +73,7 @@ typedef struct systick_reg_map {
 #define SYSTICK_CVR_TENMS               0xFFFFFF
 
 /** System elapsed time, in milliseconds */
-extern volatile uint32 systick_timer_millis;
+extern __io uint32 systick_timer_millis;
 
 void systick_init(uint32 reload_val);
 void systick_disable();
diff --git a/libmaple/util.h b/libmaple/util.h
index aff70e1..4c47764 100644
--- a/libmaple/util.h
+++ b/libmaple/util.h
@@ -50,8 +50,8 @@ extern "C"{
  * Register reads and writes
  */
 
-#define __read(reg)              (*(volatile uint32*)(reg))
-#define __write(reg, value)      (*(volatile uint32*)(reg) = (value))
+#define __read(reg)              (*(__io uint32*)(reg))
+#define __write(reg, value)      (*(__io uint32*)(reg) = (value))
 
 /*
  * Failure routines