Switch SERCOM7 (Debug UART) to sync mode + add STDIO

this will allow us to do printf()

Change-Id: Ibf4ba961d4bbf8d787558f38f3d557422587aad3
diff --git a/sysmoOCTSIM/stdio_redirect/stdio_io.c b/sysmoOCTSIM/stdio_redirect/stdio_io.c
new file mode 100644
index 0000000..7659f3d
--- /dev/null
+++ b/sysmoOCTSIM/stdio_redirect/stdio_io.c
@@ -0,0 +1,74 @@
+/**
+ * \file
+ *
+ * \brief STDIO redirection terminal
+ *
+ * Copyright (c) 2015-2018 Microchip Technology Inc. and its subsidiaries.
+ *
+ * \asf_license_start
+ *
+ * \page License
+ *
+ * Subject to your compliance with these terms, you may use Microchip
+ * software and any derivatives exclusively with Microchip products.
+ * It is your responsibility to comply with third party license terms applicable
+ * to your use of third party software (including open source software) that
+ * may accompany Microchip software.
+ *
+ * THIS SOFTWARE IS SUPPLIED BY MICROCHIP "AS IS". NO WARRANTIES,
+ * WHETHER EXPRESS, IMPLIED OR STATUTORY, APPLY TO THIS SOFTWARE,
+ * INCLUDING ANY IMPLIED WARRANTIES OF NON-INFRINGEMENT, MERCHANTABILITY,
+ * AND FITNESS FOR A PARTICULAR PURPOSE. IN NO EVENT WILL MICROCHIP BE
+ * LIABLE FOR ANY INDIRECT, SPECIAL, PUNITIVE, INCIDENTAL OR CONSEQUENTIAL
+ * LOSS, DAMAGE, COST OR EXPENSE OF ANY KIND WHATSOEVER RELATED TO THE
+ * SOFTWARE, HOWEVER CAUSED, EVEN IF MICROCHIP HAS BEEN ADVISED OF THE
+ * POSSIBILITY OR THE DAMAGES ARE FORESEEABLE.  TO THE FULLEST EXTENT
+ * ALLOWED BY LAW, MICROCHIP'S TOTAL LIABILITY ON ALL CLAIMS IN ANY WAY
+ * RELATED TO THIS SOFTWARE WILL NOT EXCEED THE AMOUNT OF FEES, IF ANY,
+ * THAT YOU HAVE PAID DIRECTLY TO MICROCHIP FOR THIS SOFTWARE.
+ *
+ * \asf_license_stop
+ *
+ */
+
+#include <stdio.h>
+#include <stdio_io.h>
+
+/** IO descriptor for STDIO access. */
+static struct io_descriptor *stdio_io = NULL;
+
+void stdio_io_init(struct io_descriptor *io)
+{
+#if defined(__GNUC__)
+	/* Specify that stdout and stdin should not be buffered. */
+	setbuf(stdout, NULL);
+	setbuf(stdin, NULL);
+	/* Note: Already the case in IAR's Normal DLIB default configuration
+	 * and AVR GCC library:
+	 * - printf() emits one character at a time.
+	 * - getchar() requests only 1 byte to exit.
+	 */
+#endif
+	stdio_io = io;
+}
+
+void stdio_io_set_io(struct io_descriptor *io)
+{
+	stdio_io = io;
+}
+
+int32_t stdio_io_read(uint8_t *buf, const int32_t len)
+{
+	if (stdio_io == NULL) {
+		return 0;
+	}
+	return io_read(stdio_io, buf, len);
+}
+
+int32_t stdio_io_write(const uint8_t *buf, const int32_t len)
+{
+	if (stdio_io == NULL) {
+		return 0;
+	}
+	return io_write(stdio_io, buf, len);
+}