ANDROID: Power: add an API to log wakeup reasons

Add API log_wakeup_reason() and expose it to userspace via sysfs path
/sys/kernel/wakeup_reasons/last_resume_reason

Change-Id: I81addaf420f1338255c5d0638b0d244a99d777d1
Signed-off-by: Ruchi Kandoi <kandoiruchi@google.com>
diff --git a/include/linux/wakeup_reason.h b/include/linux/wakeup_reason.h
new file mode 100644
index 0000000..7ce50f0
--- /dev/null
+++ b/include/linux/wakeup_reason.h
@@ -0,0 +1,23 @@
+/*
+ * include/linux/wakeup_reason.h
+ *
+ * Logs the reason which caused the kernel to resume
+ * from the suspend mode.
+ *
+ * Copyright (C) 2014 Google, Inc.
+ * This software is licensed under the terms of the GNU General Public
+ * License version 2, as published by the Free Software Foundation, and
+ * may be copied, distributed, and modified under those terms.
+ *
+ * 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.
+ */
+
+#ifndef _LINUX_WAKEUP_REASON_H
+#define _LINUX_WAKEUP_REASON_H
+
+void log_wakeup_reason(int irq);
+
+#endif /* _LINUX_WAKEUP_REASON_H */