stm32f3: be UART0 aware

cpu/stm32f3/syscalls.c

@@ -37,28 +37,42 @@
 #include "irq.h"
 #include "periph/uart.h"
 
+#ifdef MODULE_UART0
+#include "board_uart0.h"
+#endif
+
 /**
  * @brief manage the heap
  */
 extern uint32_t _end;                       /* address of last used memory cell */
 caddr_t heap_top = (caddr_t)&_end + 4;
 
+#ifndef MODULE_UART0
 /**
  * @brief use mutex for waiting on incoming UART chars
  */
 static mutex_t uart_rx_mutex;
 static char rx_buf_mem[STDIO_BUFSIZE];
 static ringbuffer_t rx_buf;
+#endif
 
 /**
  * @brief Receive a new character from the UART and put it into the receive buffer
  */
 void rx_cb(void *arg, char data)
 {
+#ifndef MODULE_UART0
     (void)arg;
 
     ringbuffer_add_one(&rx_buf, data);
     mutex_unlock(&uart_rx_mutex);
+#else
+    if (uart0_handler_pid) {
+        uart0_handle_incoming(data);
+
+        uart0_notify_thread();
+    }
+#endif
 }
 
 /**
@@ -66,10 +80,11 @@ void rx_cb(void *arg, char data)
  */
 void _init(void)
 {
+#ifndef MODULE_UART0
     mutex_init(&uart_rx_mutex);
     ringbuffer_init(&rx_buf, rx_buf_mem, STDIO_BUFSIZE);
-    uart_init(STDIO, STDIO_BAUDRATE, rx_cb, 0, 0);
-}
+#endif
+    uart_init(STDIO, STDIO_BAUDRATE, rx_cb, 0, 0);}
 
 /**
  * @brief Free resources on NewLib de-initialization, not used for RIOT
@@ -174,10 +189,15 @@ int _open_r(struct _reent *r, const char *name, int mode)
  */
 int _read_r(struct _reent *r, int fd, void *buffer, unsigned int count)
 {
+#ifndef MODULE_UART0
     while (rx_buf.avail == 0) {
         mutex_lock(&uart_rx_mutex);
     }
     return ringbuffer_get(&rx_buf, (char*)buffer, rx_buf.avail);
+#else
+    r->_errno = ENODEV;
+    return -1;
+#endif
 }
 
 /**