cc2530dk: Added a 'Serial over USB' platform process

This is based on a usb-test example by Philippe Retornaz. It has
been moved to platform and modified accordingly. With this in place:

- putchar() can work over USB. So we can use things like
  printf, slip output
- USB input can be redirected to slip or serial input

The example itself is no longer needed in the source tree

See Pull Request #18

platform/cc2530dk/dev/usb-serial.h

@@ -0,0 +1,57 @@
+/*
+ * Copyright (c) 2012, George Oikonomou (oikonomou@users.sourceforge.net)
+ * All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ * 1. Redistributions of source code must retain the above copyright
+ *    notice, this list of conditions and the following disclaimer.
+ * 2. Redistributions in binary form must reproduce the above copyright
+ *    notice, this list of conditions and the following disclaimer in the
+ *    documentation and/or other materials provided with the distribution.
+ * 3. Neither the name of the copyright holder nor the names of its
+ *    contributors may be used to endorse or promote products derived
+ *    from this software without specific prior written permission.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+ * ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+ * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
+ * FOR A PARTICULAR PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL THE
+ * COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
+ * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
+ * (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
+ * SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
+ * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT,
+ * STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
+ * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED
+ * OF THE POSSIBILITY OF SUCH DAMAGE.
+ *
+ * This file is part of the Contiki operating system.
+ */
+/**
+ * \file
+ *         Header file for cc2531's UART-like I/O over USB
+ *
+ *         With it in place, putchar can be redirected to the USB and USB
+ *         incoming traffic can be handled as input
+ *
+ * \author
+ *         George Oikonomou - <oikonomou@users.sourceforge.net>
+ */
+#ifndef USB_SERIAL_H_
+#define USB_SERIAL_H_
+
+#include "contiki.h"
+
+void usb_serial_init(void);
+void usb_serial_writeb(uint8_t);
+void usb_serial_set_input(int (*input)(unsigned char c));
+
+#if USB_SERIAL_CONF_BUFFERED
+void usb_serial_flush(void);
+#else
+#define usb_serial_flush()
+#endif
+
+#endif /* USB_SERIAL_H_ */