Usb serial (#1648)

* enabled usb clock
* added usb stack to application
* fixed pll0usb clock setup
* implemented serial usb handshake
* implemented serial communication
* integrated chibios shell
* implemented device reset
* implemented enter dfu mode
* implemented hackrf mode command
* implemented flash command
* implemented memory manipulation
* implemented button control
* fixed mode change
* improved reset behavior
* implemented directory commands
* implemented file commands
* improved data communication
* refactorings

firmware/application/usb_serial_event.cpp

@@ -0,0 +1,34 @@
+/*
+ * Copyright (C) 2023 Bernd Herzog
+ *
+ * This file is part of PortaPack.
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2, or (at your option)
+ * any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; see the file COPYING.  If not, write to
+ * the Free Software Foundation, Inc., 51 Franklin Street,
+ * Boston, MA 02110-1301, USA.
+ */
+
+#include "usb_serial_event.hpp"
+
+#include "portapack.hpp"
+
+extern "C" {
+void on_channel_opened() {
+    portapack::usb_serial.on_channel_opened();
+}
+
+void on_channel_closed() {
+    portapack::usb_serial.on_channel_closed();
+}
+}