cpu/msp430fxyz: make use of uart_stdio module

cpu/msp430fxyz/Makefile.include

@@ -2,4 +2,6 @@ INCLUDES += -I$(RIOTCPU)/msp430fxyz/include/
 
 include $(RIOTCPU)/msp430-common/Makefile.include
 
-export USEMODULE += periph hwtimer_compat
+USEMODULE += periph
+USEMODULE += hwtimer_compat
+export USEMODULE

cpu/msp430fxyz/include/msp430_stdio.h

@@ -0,0 +1,37 @@
+/*
+ * Copyright (C) 2015 Freie Universität Berlin
+ *
+ * This file is subject to the terms and conditions of the GNU Lesser
+ * General Public License v2.1. See the file LICENSE in the top level
+ * directory for more details.
+ */
+
+/**
+ * @ingroup     cpu_msp430fxyz
+ *
+ * @{
+ * @file
+ * @brief       STDIO over UART for MSP430 platforms
+ *
+ * @author      Hauke Petersen <hauke.petersen@fu-berlin.de>
+ */
+
+#ifndef MSP430_STDIO_H
+#define MSP430_STDIO_H
+
+#ifdef __cplusplus
+extern "C" {
+#endif
+
+/**
+ * @brief   Initialize the STDIO data structured and the underlying UART driver
+ *          as define in board.h
+ */
+void msp430_stdio_init(void);
+
+#ifdef __cplusplus
+}
+#endif
+
+#endif /* MSP430_STDIO_H */
+/** @} */

cpu/msp430fxyz/msp430_stdio.c

@@ -0,0 +1,86 @@
+/*
+ * Copyright (C) 2015 Freie Universität Berlin
+ *
+ * This file is subject to the terms and conditions of the GNU Lesser
+ * General Public License v2.1. See the file LICENSE in the top level
+ * directory for more details.
+ */
+
+/**
+ * @ingroup     cpu_msp430fxyz
+ * @{
+ *
+ * @file
+ * @brief       Implementation of getchar and putchar for MSP430 CPUs
+ *
+ * @author      Hauke Petersen <hauke.petersen@fu-berlin.de>
+ *
+ * @}
+ */
+
+#include "irq.h"
+#include "mutex.h"
+#include "board.h"
+#include "ringbuffer.h"
+#include "periph/uart.h"
+
+#include <stdio.h>
+
+static mutex_t rx_lock = MUTEX_INIT;
+static ringbuffer_t rx_buf;
+static char rx_buf_mem[STDIO_RX_BUFSIZE];
+
+static inline int safe_read(void)
+{
+    int res;
+    unsigned state = disableIRQ();
+    res = ringbuffer_get_one(&rx_buf);
+    restoreIRQ(state);
+    return res;
+}
+
+static void rx_cb(void *arg, char data)
+{
+    (void)arg;
+
+    ringbuffer_add_one(&rx_buf, data);
+    /* this is a little dirty hack: it seems the MSP430 boards are too slow for
+     * processing data @ 115200 baud and calling mutex_unock() for each byte. By
+     * asserting, that the STDIO is used for the shell and we are only
+     * interested in completed lines anyway, we can reduce the overhead here by
+     * only waking the shell on newline chars */
+    if (data == '\n') {
+        mutex_unlock(&rx_lock);
+    }
+}
+
+void msp430_stdio_init(void)
+{
+    mutex_lock(&rx_lock);
+    ringbuffer_init(&rx_buf, rx_buf_mem, STDIO_RX_BUFSIZE);
+    uart_init(STDIO, STDIO_BAUDRATE, rx_cb, NULL, 0);
+}
+
+/**
+ * @brief   Get one character from STDIO - used by the libc
+ */
+int getchar(void)
+{
+    int res = safe_read();
+
+    while (res == -1) {
+        mutex_lock(&rx_lock);
+        res = safe_read();
+    }
+    return res;
+}
+
+/**
+ * @brief   Write one character to the STDIO UART interface - used by e.g.
+ *          printf and puts
+ */
+int putchar(int c)
+{
+    uart_write_blocking(STDIO, (char)c);
+    return 1;
+}