Add hardware buttons, cpu booting, tsec booting.

hwinit/btn.h

@@ -0,0 +1,13 @@
+#ifndef _BTN_H_
+#define _BTN_H_
+
+#include "types.h"
+
+#define BTN_POWER 0x1
+#define BTN_VOL_DOWN 0x2
+#define BTN_VOL_UP 0x4
+
+u32 btn_read();
+u32 btn_wait();
+
+#endif