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.

examples/platforms/cc2538/Makefile.am

@@ -37,6 +37,7 @@ libopenthread_cc2538_a_CPPFLAGS           = \
 
 libopenthread_cc2538_a_SOURCES            = \
     alarm.c                                 \
+    misc.c                                  \
     logging.c                               \
     platform.c                              \
     radio.c                                 \

examples/platforms/cc2538/cc2538-reg.h

@@ -98,6 +98,9 @@
 #define SYS_CTRL_SYSDIV_32MHZ                 0x00000000  // Sys_div for sysclk 32MHz  
 #define SYS_CTRL_CLOCK_CTRL_AMP_DET           0x00200000
 
+#define SYS_CTRL_PWRDBG                       0x400D2074
+#define SYS_CTRL_PWRDBG_FORCE_WARM_RESET      0x00000008
+
 #define SYS_CTRL_RCGCUART                     0x400D2028
 #define SYS_CTRL_SCGCUART                     0x400D202C
 #define SYS_CTRL_DCGCUART                     0x400D2030

examples/platforms/cc2538/misc.c

@@ -0,0 +1,41 @@
+/*
+ *  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.
+ */
+
+#include <platform/misc.h>
+#include "platform-cc2538.h"
+
+void otPlatReset(void)
+{
+    HWREG(SYS_CTRL_PWRDBG) = SYS_CTRL_PWRDBG_FORCE_WARM_RESET;
+}
+
+otPlatResetReason otPlatGetResetReason(void)
+{
+    // TODO: Write me!
+    return kPlatResetReason_PowerOn;
+}

examples/platforms/posix/Makefile.am

@@ -38,6 +38,7 @@ libopenthread_posix_a_CPPFLAGS            = \
 
 libopenthread_posix_a_SOURCES             = \
     alarm.c                                 \
+    misc.c                                  \
     logging.c                               \
     platform.c                              \
     radio.c                                 \

examples/platforms/posix/misc.c

@@ -0,0 +1,40 @@
+/*
+ *  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.
+ */
+
+#include <platform/misc.h>
+#include "platform-posix.h"
+
+void otPlatReset(void)
+{
+    // This function does nothing on the Posix platform.
+}
+
+otPlatResetReason otPlatGetResetReason(void)
+{
+    return kPlatResetReason_PowerOn;
+}