From 5beceaae5c57dcf1b92d1def5954ac331a19a63a Mon Sep 17 00:00:00 2001
From: Kevin O'Connor <kevin@koconnor.net>
Date: Mon, 23 Jan 2017 11:13:19 -0500
Subject: [PATCH] io.h: read/write[bwl] should use barrier

Add barrier() calls to low-level read/write io calls so that their
callers don't need to.

Signed-off-by: Kevin O'Connor <kevin@koconnor.net>
---
 src/avr/serial.c     |  3 ---
 src/generic/io.h     | 16 +++++++++++++---
 src/sam3x8e/serial.c |  3 ---
 3 files changed, 13 insertions(+), 9 deletions(-)

diff --git a/src/avr/serial.c b/src/avr/serial.c
index 0b5fea1f..32619ecc 100644
--- a/src/avr/serial.c
+++ b/src/avr/serial.c
@@ -126,12 +126,10 @@ console_get_output(uint8_t len)
         return NULL;
     // Disable TX irq and move buffer
     writeb(&transmit_max, 0);
-    barrier();
     tpos = readb(&transmit_pos);
     tmax -= tpos;
     memmove(&transmit_buf[0], &transmit_buf[tpos], tmax);
     writeb(&transmit_pos, 0);
-    barrier();
     writeb(&transmit_max, tmax);
     enable_tx_irq();
     return &transmit_buf[tmax];
@@ -141,7 +139,6 @@ console_get_output(uint8_t len)
 void
 console_push_output(uint8_t len)
 {
-    barrier();
     writeb(&transmit_max, readb(&transmit_max) + len);
     enable_tx_irq();
 }
diff --git a/src/generic/io.h b/src/generic/io.h
index 2a16cf20..12bbd489 100644
--- a/src/generic/io.h
+++ b/src/generic/io.h
@@ -2,24 +2,34 @@
 #define __GENERIC_IO_H
 
 #include <stdint.h> // uint32_t
+#include "compiler.h" // barrier
 
 static inline void writel(void *addr, uint32_t val) {
+    barrier();
     *(volatile uint32_t *)addr = val;
 }
 static inline void writew(void *addr, uint16_t val) {
+    barrier();
     *(volatile uint16_t *)addr = val;
 }
 static inline void writeb(void *addr, uint8_t val) {
+    barrier();
     *(volatile uint8_t *)addr = val;
 }
 static inline uint32_t readl(const void *addr) {
-    return *(volatile const uint32_t *)addr;
+    uint32_t val = *(volatile const uint32_t *)addr;
+    barrier();
+    return val;
 }
 static inline uint16_t readw(const void *addr) {
-    return *(volatile const uint16_t *)addr;
+    uint16_t val = *(volatile const uint16_t *)addr;
+    barrier();
+    return val;
 }
 static inline uint8_t readb(const void *addr) {
-    return *(volatile const uint8_t *)addr;
+    uint8_t val = *(volatile const uint8_t *)addr;
+    barrier();
+    return val;
 }
 
 #endif // io.h
diff --git a/src/sam3x8e/serial.c b/src/sam3x8e/serial.c
index a14f97fb..3532d5f3 100644
--- a/src/sam3x8e/serial.c
+++ b/src/sam3x8e/serial.c
@@ -131,12 +131,10 @@ console_get_output(uint8_t len)
         return NULL;
     // Disable TX irq and move buffer
     writeb(&transmit_max, 0);
-    barrier();
     tpos = readb(&transmit_pos);
     tmax -= tpos;
     memmove(&transmit_buf[0], &transmit_buf[tpos], tmax);
     writeb(&transmit_pos, 0);
-    barrier();
     writeb(&transmit_max, tmax);
     enable_tx_irq();
     return &transmit_buf[tmax];
@@ -146,7 +144,6 @@ console_get_output(uint8_t len)
 void
 console_push_output(uint8_t len)
 {
-    barrier();
     writeb(&transmit_max, readb(&transmit_max) + len);
     enable_tx_irq();
 }