firmware/ice40-riscv: Import common parts to all iCE40/RISC-V firmwares

Signed-off-by: Sylvain Munaut <tnt@246tNt.com>
diff --git a/firmware/ice40-riscv/common/console.h b/firmware/ice40-riscv/common/console.h
new file mode 100644
index 0000000..2645927
--- /dev/null
+++ b/firmware/ice40-riscv/common/console.h
@@ -0,0 +1,16 @@
+/*
+ * console.h
+ *
+ * Copyright (C) 2019-2020  Sylvain Munaut <tnt@246tNt.com>
+ * SPDX-License-Identifier: LGPL-3.0-or-later
+ */
+
+#pragma once
+
+void console_init(void);
+
+char getchar(void);
+int  getchar_nowait(void);
+void putchar(char c);
+void puts(const char *p);
+int  printf(const char *fmt, ...);