[ncp] new spinel property to trigger/test watchdog (openthread#2374)

doc/spinel-protocol-src/spinel-prop-debug.md

@@ -30,3 +30,11 @@ If the NCP supports dynamic log level control, setting this property
 changes the log level accordingly. Getting the value returns the current
 log level.  If the dynamic log level control is not supported, setting this
 property returns a `PROP_LAST_STATUS` with `STATUS_INVALID_COMMAND_FOR_PROP`.
+
+### PROP 16386: PROP_DEBUG_TEST_WATCHDOG {#prop-debug-test-watchdog}
+* Type: Read-Only
+* Packed-Encoding: Empty
+
+Reading this property will causes NCP to start `while(true) ;` loop and
+thus triggering a watchdog. This is intended for testing the watchdog
+functionality on the underlying platform/NCP.

src/ncp/ncp_base.cpp

@@ -63,6 +63,7 @@ const NcpBase::PropertyHandlerEntry NcpBase::mGetPropertyHandlerTable[] =
 {
     NCP_GET_PROP_HANDLER_ENTRY(CAPS),
     NCP_GET_PROP_HANDLER_ENTRY(DEBUG_TEST_ASSERT),
+    NCP_GET_PROP_HANDLER_ENTRY(DEBUG_TEST_WATCHDOG),
     NCP_GET_PROP_HANDLER_ENTRY(DEBUG_NCP_LOG_LEVEL),
     NCP_GET_PROP_HANDLER_ENTRY(HWADDR),
     NCP_GET_PROP_HANDLER_ENTRY(HOST_POWER_STATE),
@@ -1852,6 +1853,16 @@ otError NcpBase::GetPropertyHandler_DEBUG_TEST_ASSERT(void)
     )
 }
 
+otError NcpBase::GetPropertyHandler_DEBUG_TEST_WATCHDOG(void)
+{
+    while (true)
+        ;
+
+    OT_UNREACHABLE_CODE(
+        return OT_ERROR_NONE;
+    )
+}
+
 otError NcpBase::GetPropertyHandler_DEBUG_NCP_LOG_LEVEL(void)
 {
     uint8_t logLevel = 0;

src/ncp/ncp_base.hpp

@@ -321,6 +321,7 @@ class NcpBase
     NCP_GET_PROP_HANDLER(VENDOR_ID);
     NCP_GET_PROP_HANDLER(CAPS);
     NCP_GET_PROP_HANDLER(DEBUG_TEST_ASSERT);
+    NCP_GET_PROP_HANDLER(DEBUG_TEST_WATCHDOG);
     NCP_GET_PROP_HANDLER(DEBUG_NCP_LOG_LEVEL);
     NCP_SET_PROP_HANDLER(DEBUG_NCP_LOG_LEVEL);
     NCP_GET_PROP_HANDLER(NCP_VERSION);

src/ncp/spinel.c

@@ -1781,6 +1781,10 @@ spinel_prop_key_to_cstr(spinel_prop_key_t prop_key)
         ret = "PROP_DEBUG_NCP_LOG_LEVEL";
         break;
 
+    case SPINEL_PROP_DEBUG_TEST_WATCHDOG:
+        ret = "PROP_DEBUG_TEST_WATCHDOG";
+        break;
+
     default:
         break;
     }

src/ncp/spinel.h

@@ -1555,18 +1555,30 @@ typedef enum
 
     SPINEL_PROP_DEBUG__BEGIN            = 16384,
 
-    /// Reading this property will cause an assert on the NCP.
-    /// This is intended for testing the assert functionality of
-    /// underlying platform/NCP. Assert should ideally cause the
-    /// NCP to reset, but if this is not supported a `false` boolean
-    /// is returned in response.
-    /** Format: 'b' (read-only) */
+    /// Testing platform assert
+    /** Format: 'b' (read-only)
+     *
+     * Reading this property will cause an assert on the NCP. This is intended for testing the assert functionality of
+     * underlying platform/NCP. Assert should ideally cause the NCP to reset, but if this is not supported a `false`
+     * boolean is returned in response.
+     *
+     */
     SPINEL_PROP_DEBUG_TEST_ASSERT       = SPINEL_PROP_DEBUG__BEGIN + 0,
 
     /// The NCP log level.
     /** Format: `C` */
     SPINEL_PROP_DEBUG_NCP_LOG_LEVEL     = SPINEL_PROP_DEBUG__BEGIN + 1,
 
+    /// Testing platform watchdog
+    /** Format: Empty  (read-only)
+     *
+     * Reading this property will causes NCP to start a `while(true) ;` loop and thus triggering a watchdog.
+     *
+     * This is intended for testing the watchdog functionality on the underlying platform/NCP.
+     *
+     */
+    SPINEL_PROP_DEBUG_TEST_WATCHDOG     = SPINEL_PROP_DEBUG__BEGIN + 2,
+
     SPINEL_PROP_DEBUG__END              = 17408,
 
     SPINEL_PROP_EXPERIMENTAL__BEGIN     = 2000000,