Add BSP and semihosting library for nios2-generic-nommu QEMU emulation.

libgloss/nios2/io-nios2.S

@@ -0,0 +1,31 @@
+/*
+ * Low-level semihosting primitive for csky. 
+ *
+ * Copyright (c) 2018 Mentor Graphics
+ *
+ * The authors hereby grant permission to use, copy, modify, distribute,
+ * and license this software and its documentation for any purpose, provided
+ * that existing copyright notices are retained in all copies and that this
+ * notice is included verbatim in any distributions. No written agreement,
+ * license, or royalty fee is required for any of the authorized uses.
+ * Modifications to this software may be copyrighted by their authors
+ * and need not follow the licensing terms described here, provided that
+ * the new terms are clearly indicated on the first page of each file where
+ * they apply.
+ */
+
+/* Implement
+     void __io_hosted (int func, void *args);
+   by causing a break 1.  The break handler can find the two parameters in
+   r4 and r5 per the normal C calling convention.  */
+
+	.text
+	.align	2
+	.global	__io_hosted
+	.type	_io_hosted, @function
+
+__io_hosted:
+	break 1
+	ret
+
+	.size	__io_hosted, .-__io_hosted