Added platform APIs for handling resets. (#284)

This change includes the addition of two new platform API functions:

* `otPlatReset()`
* `otPlatGetResetReason()`

They are pretty straightforward. Every platform must implement both, but
`otPlatReset()` is allowed to simply return if the platform doesn't support
being reset (like the posix platform).

This commit addresses issue #283.

include/platform/Makefile.am

@@ -30,6 +30,7 @@ include $(abs_top_nlbuild_autotools_dir)/automake/pre.am
 
 ot_platform_headers                      =\
     alarm.h                               \
+    misc.h                                \
     logging.h                             \
     radio.h                               \
     random.h                              \

include/platform/misc.h

@@ -0,0 +1,81 @@
+/*
+ *  Copyright (c) 2016, Nest Labs, Inc.
+ *  All rights reserved.
+ *
+ *  Redistribution and use in source and binary forms, with or without
+ *  modification, are permitted provided that the following conditions are met:
+ *  1. Redistributions of source code must retain the above copyright
+ *     notice, this list of conditions and the following disclaimer.
+ *  2. Redistributions in binary form must reproduce the above copyright
+ *     notice, this list of conditions and the following disclaimer in the
+ *     documentation and/or other materials provided with the distribution.
+ *  3. Neither the name of the copyright holder nor the
+ *     names of its contributors may be used to endorse or promote products
+ *     derived from this software without specific prior written permission.
+ *
+ *  THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
+ *  AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
+ *  IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
+ *  ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE
+ *  LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
+ *  CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
+ *  SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
+ *  INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
+ *  CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
+ *  ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
+ *  POSSIBILITY OF SUCH DAMAGE.
+ */
+
+/**
+ * @file
+ * @brief
+ *   This file includes platform abstractions for miscelaneous behaviors.
+ */
+
+#ifndef OT_PLATFORM_MISC_H
+#define OT_PLATFORM_MISC_H 1
+
+#include <stdint.h>
+
+#ifdef __cplusplus
+extern "C" {
+#endif
+
+/**
+ * This function performs a software reset on the platform, if supported.
+ *
+ */
+void otPlatReset(void);
+
+/**
+ * Enumeration of possible reset reason codes.
+ *
+ * These are in the same order as the Spinel reset reason codes.
+ *
+ */
+typedef enum
+{
+    kPlatResetReason_PowerOn        = 0,
+    kPlatResetReason_External       = 1,
+    kPlatResetReason_Software       = 2,
+    kPlatResetReason_Fault          = 3,
+    kPlatResetReason_Crash          = 4,
+    kPlatResetReason_Assert         = 5,
+    kPlatResetReason_Other          = 6,
+    kPlatResetReason_Unknown        = 7,
+    kPlatResetReason_Watchdog       = 8,
+
+    kPlatResetReason_Count,
+} otPlatResetReason;
+
+/**
+ * This function returns the reason for the last platform reset.
+ *
+ */
+otPlatResetReason otPlatGetResetReason(void);
+
+#ifdef __cplusplus
+}  // extern "C"
+#endif
+
+#endif  // OT_PLATFORM_MISC_H