[spinel] stop Spinel time sync when Thread satck is not running (#10573)

The radio_spinel periodically send Spinel command
SPINEL_PROP_RCP_TIMESTAMP to RCP to synchronize time between host
and RCP. Even if Thread stack is not running, it will periodically
wake up the Thread host.

This commit stops the time sync when the Thread stack is not running
to save host power.

src/lib/spinel/radio_spinel.cpp

@@ -111,7 +111,8 @@ RadioSpinel::RadioSpinel(void)
     , mVendorRestorePropertiesCallback(nullptr)
     , mVendorRestorePropertiesContext(nullptr)
 #endif
-    , mEnableRcpTimeSync(false)
+    , mTimeSyncEnabled(false)
+    , mTimeSyncOn(false)
     , mSpinelDriver(nullptr)
 {
     memset(&mRadioSpinelMetrics, 0, sizeof(mRadioSpinelMetrics));
@@ -134,7 +135,7 @@ void RadioSpinel::Init(bool          aSkipRcpCompatibilityCheck,
     mResetRadioOnStartup = aSoftwareReset;
 #endif
 
-    mEnableRcpTimeSync = aEnableRcpTimeSync;
+    mTimeSyncEnabled = aEnableRcpTimeSync;
 
     mSpinelDriver = aSpinelDriver;
     mSpinelDriver->SetFrameHandler(&HandleReceivedFrame, &HandleSavedFrame, this);
@@ -798,7 +799,7 @@ void RadioSpinel::Process(const void *aContext)
     ProcessRadioStateMachine();
     RecoverFromRcpFailure();
 
-    if (mEnableRcpTimeSync)
+    if (mTimeSyncEnabled)
     {
         CalcRcpTimeOffset();
     }
@@ -1919,6 +1920,7 @@ void RadioSpinel::CalcRcpTimeOffset(void)
      *         D = T1' - ((T0 + T2)/ 2)
      */
 
+    EXPECT(mTimeSyncOn, NO_ACTION);
     EXPECT(!mIsTimeSynced || (otPlatTimeGet() >= GetNextRadioTimeRecalcStart()), NO_ACTION);
 
     LogDebg("Trying to get RCP time offset");
@@ -2231,7 +2233,7 @@ void RadioSpinel::RestoreProperties(void)
     }
 #endif
 
-    if (mEnableRcpTimeSync)
+    if (mTimeSyncEnabled)
     {
         CalcRcpTimeOffset();
     }

src/lib/spinel/radio_spinel.hpp

@@ -1106,6 +1106,14 @@ public:
     void SetVendorRestorePropertiesCallback(otRadioSpinelVendorRestorePropertiesCallback aCallback, void *aContext);
 #endif // OPENTHREAD_SPINEL_CONFIG_VENDOR_HOOK_ENABLE
 
+    /**
+     * Enables or disables the time synchronization between the host and RCP.
+     *
+     * @param[in]  aOn  TRUE to turn on the time synchronization, FALSE otherwise.
+     *
+     */
+    void SetTimeSyncState(bool aOn) { mTimeSyncOn = aOn; }
+
 private:
     enum
     {
@@ -1342,7 +1350,8 @@ private:
     void                                        *mVendorRestorePropertiesContext;
 #endif
 
-    bool mEnableRcpTimeSync;
+    bool mTimeSyncEnabled : 1;
+    bool mTimeSyncOn : 1;
 
     SpinelDriver *mSpinelDriver;
 };

src/posix/platform/openthread-core-posix-config.h

@@ -156,4 +156,11 @@
 #define OPENTHREAD_CONFIG_PLATFORM_POWER_CALIBRATION_ENABLE 1
 #endif
 
+#ifndef OPENTHREAD_CONFIG_MAX_STATECHANGE_HANDLERS
+/**
+ * The `system.cpp` has registered a state-changed callback handler. Another state-changed callback handler
+ * is reserved for application use.
+ */
+#define OPENTHREAD_CONFIG_MAX_STATECHANGE_HANDLERS 2
+#endif
 #endif // OPENTHREAD_CORE_POSIX_CONFIG_H_

src/posix/platform/platform-posix.h

@@ -165,6 +165,15 @@ void platformRadioInit(const char *aUrl);
  */
 void platformRadioDeinit(void);
 
+/**
+ * Handles the state change events for the radio driver.
+ *
+ * @param[in] aInstance  A pointer to the OpenThread instance.
+ * @param[in] aFlags     Flags that denote the state change events.
+ *
+ */
+void platformRadioHandleStateChange(otInstance *aInstance, otChangedFlags aFlags);
+
 /**
  * Inputs a received radio frame.
  *

src/posix/platform/radio.cpp

@@ -216,6 +216,14 @@ ot::Posix::RcpCapsDiag &GetRcpCapsDiag(void) { return sRadio.GetRcpCapsDiag(); }
 
 void platformRadioDeinit(void) { GetRadioSpinel().Deinit(); }
 
+void platformRadioHandleStateChange(otInstance *aInstance, otChangedFlags aFlags)
+{
+    if (OT_CHANGED_THREAD_NETIF_STATE & aFlags)
+    {
+        GetRadioSpinel().SetTimeSyncState(otIp6IsEnabled(aInstance));
+    }
+}
+
 void otPlatRadioGetIeeeEui64(otInstance *aInstance, uint8_t *aIeeeEui64)
 {
     OT_UNUSED_VARIABLE(aInstance);

src/posix/platform/system.cpp

@@ -65,7 +65,6 @@ bool        gDryRun   = false;
 
 CoprocessorType sCoprocessorType = OT_COPROCESSOR_UNKNOWN;
 
-#if OPENTHREAD_CONFIG_PLATFORM_NETIF_ENABLE || OPENTHREAD_CONFIG_BACKBONE_ROUTER_ENABLE
 static void processStateChange(otChangedFlags aFlags, void *aContext)
 {
     otInstance *instance = static_cast<otInstance *>(aContext);
@@ -80,8 +79,9 @@ static void processStateChange(otChangedFlags aFlags, void *aContext)
 #if OPENTHREAD_CONFIG_BACKBONE_ROUTER_ENABLE
     ot::Posix::InfraNetif::Get().HandleBackboneStateChange(instance, aFlags);
 #endif
+
+    platformRadioHandleStateChange(instance, aFlags);
 }
-#endif
 
 static const char *get802154RadioUrl(const otPlatformCoprocessorUrls &aUrls)
 {
@@ -245,9 +245,7 @@ void platformSetUp(otPlatformConfig *aPlatformConfig)
     ot::Posix::Daemon::Get().SetUp();
 #endif
 
-#if OPENTHREAD_CONFIG_PLATFORM_NETIF_ENABLE || OPENTHREAD_CONFIG_BACKBONE_ROUTER_ENABLE
     SuccessOrDie(otSetStateChangedCallback(gInstance, processStateChange, gInstance));
-#endif
 
 exit:
     return;