samd21: Initial support for SAMD21 micro-controllers

Add initial support for the Atmel SAMD21 micro-controllers.

Signed-off-by: Kevin O'Connor <kevin@koconnor.net>

src/samd21/main.c

@@ -0,0 +1,32 @@
+// Main starting point for SAMD21 boards
+//
+// Copyright (C) 2018  Kevin O'Connor <kevin@koconnor.net>
+//
+// This file may be distributed under the terms of the GNU GPLv3 license.
+
+#include "command.h" // DECL_CONSTANT
+#include "samd21.h" // SystemInit
+#include "sched.h" // sched_main
+
+DECL_CONSTANT(MCU, "samd21g");
+
+
+/****************************************************************
+ * misc functions
+ ****************************************************************/
+
+void
+command_reset(uint32_t *args)
+{
+    NVIC_SystemReset();
+}
+DECL_COMMAND_FLAGS(command_reset, HF_IN_SHUTDOWN, "reset");
+
+// Main entry point
+int
+main(void)
+{
+    SystemInit();
+    sched_main();
+    return 0;
+}