[examples] Introducing pseudo resets (#2621)

Pseudo resets allow for `otPlatReset()` to reset the OpenThread state
without resetting the chip. This is important if the SoC is presenting
itself as a USB device.

The build option `OPENTHREAD_PLATFORM_USE_PSEUDO_RESET` can be used to
force this feature to be enabled or disabled by setting it to `1` or
`0` accordingly. Otherwise it will be set to a platform-specified
default value.

examples/apps/cli/main.c

@@ -63,6 +63,8 @@ int main(int argc, char *argv[])
     uint8_t *otInstanceBuffer       = NULL;
 #endif
 
+pseudo_reset:
+
     PlatformInit(argc, argv);
 
 #if OPENTHREAD_ENABLE_MULTIPLE_INSTANCES
@@ -86,17 +88,19 @@ int main(int argc, char *argv[])
     otDiagInit(sInstance);
 #endif
 
-    while (1)
+    while (!PlatformPseudoResetWasRequested())
     {
         otTaskletsProcess(sInstance);
         PlatformProcessDrivers(sInstance);
     }
 
-        // otInstanceFinalize(sInstance);
+    otInstanceFinalize(sInstance);
 #if OPENTHREAD_ENABLE_MULTIPLE_INSTANCES
-        // free(otInstanceBuffer);
+    free(otInstanceBuffer);
 #endif
 
+    goto pseudo_reset;
+
     return 0;
 }
 

examples/apps/ncp/main.c

@@ -62,6 +62,8 @@ int main(int argc, char *argv[])
     uint8_t *otInstanceBuffer       = NULL;
 #endif
 
+pseudo_reset:
+
     PlatformInit(argc, argv);
 
 #if OPENTHREAD_ENABLE_MULTIPLE_INSTANCES
@@ -85,17 +87,19 @@ int main(int argc, char *argv[])
     otDiagInit(sInstance);
 #endif
 
-    while (1)
+    while (!PlatformPseudoResetWasRequested())
     {
         otTaskletsProcess(sInstance);
         PlatformProcessDrivers(sInstance);
     }
 
-        // otInstanceFinalize(sInstance);
+    otInstanceFinalize(sInstance);
 #if OPENTHREAD_ENABLE_MULTIPLE_INSTANCES
-        // free(otInstanceBuffer);
+    free(otInstanceBuffer);
 #endif
 
+    goto pseudo_reset;
+
     return 0;
 }
 

examples/platforms/cc2538/platform.c

@@ -49,6 +49,11 @@ void PlatformInit(int argc, char *argv[])
     (void)argv;
 }
 
+bool PlatformPseudoResetWasRequested(void)
+{
+    return false;
+}
+
 void PlatformProcessDrivers(otInstance *aInstance)
 {
     sInstance = aInstance;

examples/platforms/cc2650/platform.c

@@ -57,6 +57,11 @@ void PlatformInit(int argc, char *argv[])
     cc2650RadioInit();
 }
 
+bool PlatformPseudoResetWasRequested(void)
+{
+    return false;
+}
+
 /**
  * Function documented in platform-cc2650.h
  */

examples/platforms/cc2652/platform.c

@@ -71,6 +71,11 @@ void PlatformInit(int argc, char *argv[])
     cc2652RadioInit();
 }
 
+bool PlatformPseudoResetWasRequested(void)
+{
+    return false;
+}
+
 /**
  * Function documented in platform-cc2652.h
  */

examples/platforms/da15000/platform.c

@@ -138,6 +138,11 @@ void PlatformInit(int argc, char *argv[])
     (void)argv;
 }
 
+bool PlatformPseudoResetWasRequested(void)
+{
+    return false;
+}
+
 static sys_clk_t ClkGet(void)
 {
     sys_clk_t clk    = sysclk_RC16;

examples/platforms/efr32/platform.c

@@ -66,6 +66,11 @@ void PlatformInit(int argc, char *argv[])
     efr32RandomInit();
 }
 
+bool PlatformPseudoResetWasRequested(void)
+{
+    return false;
+}
+
 void PlatformDeinit(void)
 {
     efr32RadioDeinit();

examples/platforms/emsk/platform.c

@@ -53,6 +53,11 @@ void PlatformInit(int argc, char *argv[])
     (void)argv;
 }
 
+bool PlatformPseudoResetWasRequested(void)
+{
+    return false;
+}
+
 void PlatformProcessDrivers(otInstance *aInstance)
 {
     emskUartProcess();

examples/platforms/gp712/platform.c

@@ -76,6 +76,11 @@ void PlatformInit(int argc, char *argv[])
     qorvoRadioInit();
 }
 
+bool PlatformPseudoResetWasRequested(void)
+{
+    return false;
+}
+
 void PlatformProcessDrivers(otInstance *aInstance)
 {
     if (localInstance == NULL)

examples/platforms/kw41z/platform.c

@@ -100,6 +100,11 @@ void PlatformInit(int argc, char *argv[])
     (void)argv;
 }
 
+bool PlatformPseudoResetWasRequested(void)
+{
+    return false;
+}
+
 void PlatformDeinit(void)
 {
 }

examples/platforms/nrf52840/alarm.c

@@ -339,6 +339,9 @@ static void AlarmStop(AlarmIndex aIndex)
 void nrf5AlarmInit(void)
 {
     memset(sTimerData, 0, sizeof(sTimerData));
+    sOverflowCounter = 0;
+    sMutex           = 0;
+    sTimeOffset      = 0;
 
     // Setup low frequency clock.
     nrf_drv_clock_lfclk_request(NULL);

examples/platforms/nrf52840/misc.c

@@ -40,6 +40,8 @@
 
 static uint32_t sResetReason;
 
+bool gPlatformPseudoResetWasRequested;
+
 __WEAK void nrf5CryptoInit(void)
 {
     // This function is defined as weak so it could be overridden with external implementation.
@@ -69,8 +71,12 @@ void nrf5MiscDeinit(void)
 void otPlatReset(otInstance *aInstance)
 {
     (void)aInstance;
-
+#if OPENTHREAD_PLATFORM_USE_PSEUDO_RESET
+    gPlatformPseudoResetWasRequested = true;
+    sResetReason                     = POWER_RESETREAS_SREQ_Msk;
+#else  // if OPENTHREAD_PLATFORM_USE_PSEUDO_RESET
     NVIC_SystemReset();
+#endif // else OPENTHREAD_PLATFORM_USE_PSEUDO_RESET
 }
 
 otPlatResetReason otPlatGetResetReason(otInstance *aInstance)

examples/platforms/nrf52840/platform-config.h

@@ -347,6 +347,16 @@
 #define USB_CDC_AS_SERIAL_TRANSPORT 0
 #endif
 
+/**
+ * @def OPENTHREAD_PLATFORM_USE_PSEUDO_RESET
+ *
+ * Reset the application, not the chip, when a software reset is requested.
+ * via `otPlatReset()`.
+ */
+#ifndef OPENTHREAD_PLATFORM_USE_PSEUDO_RESET
+#define OPENTHREAD_PLATFORM_USE_PSEUDO_RESET USB_CDC_AS_SERIAL_TRANSPORT
+#endif
+
 /*******************************************************************************
  * @section Radio driver configuration.
  ******************************************************************************/

examples/platforms/nrf52840/platform.c

@@ -51,6 +51,18 @@ void __cxa_pure_virtual(void)
 
 void PlatformInit(int argc, char *argv[])
 {
+    extern bool gPlatformPseudoResetWasRequested;
+
+    if (gPlatformPseudoResetWasRequested)
+    {
+        nrf5AlarmDeinit();
+        nrf5AlarmInit();
+
+        gPlatformPseudoResetWasRequested = false;
+
+        return;
+    }
+
     (void)argc;
     (void)argv;
 
@@ -87,6 +99,12 @@ void PlatformDeinit(void)
 #endif
 }
 
+bool PlatformPseudoResetWasRequested(void)
+{
+    extern bool gPlatformPseudoResetWasRequested;
+    return gPlatformPseudoResetWasRequested;
+}
+
 void PlatformProcessDrivers(otInstance *aInstance)
 {
     nrf5AlarmProcess(aInstance);

examples/platforms/platform.h

@@ -53,6 +53,14 @@ void PlatformInit(int argc, char *argv[]);
  */
 void PlatformDeinit(void);
 
+/**
+ * This function returns true is a pseudo-reset was requested.
+ * In such a case, the main loop should shut down and re-initialize
+ * the OpenThread instance.
+ *
+ */
+bool PlatformPseudoResetWasRequested(void);
+
 /**
  * This function performs all platform-specific processing.
  *

examples/platforms/posix/misc.c

@@ -42,9 +42,20 @@ extern int    gArgumentsCount;
 extern char **gArguments;
 #endif
 
+static otPlatResetReason sPlatResetReason = OT_PLAT_RESET_REASON_POWER_ON;
+bool                     gPlatformPseudoResetWasRequested;
+
 void otPlatReset(otInstance *aInstance)
 {
-#ifndef _WIN32
+#if _WIN32
+// This function does nothing on the Windows platform.
+
+#elif OPENTHREAD_PLATFORM_USE_PSEUDO_RESET // if _WIN32
+    gPlatformPseudoResetWasRequested = true;
+    sPlatResetReason                 = OT_PLAT_RESET_REASON_SOFTWARE;
+
+#else // elif OPENTHREAD_PLATFORM_USE_PSEUDO_RESET
+    // Restart the process using execvp.
     char *argv[gArgumentsCount + 1];
 
     for (int i = 0; i < gArgumentsCount; ++i)
@@ -62,16 +73,16 @@ void otPlatReset(otInstance *aInstance)
     execvp(argv[0], argv);
     perror("reset failed");
     exit(EXIT_FAILURE);
-#else
-// This function does nothing on the Windows platform.
-#endif // _WIN32
+
+#endif // else OPENTHREAD_PLATFORM_USE_PSEUDO_RESET
+
     (void)aInstance;
 }
 
 otPlatResetReason otPlatGetResetReason(otInstance *aInstance)
 {
     (void)aInstance;
-    return OT_PLAT_RESET_REASON_POWER_ON;
+    return sPlatResetReason;
 }
 
 void otPlatWakeHost(void)

examples/platforms/posix/platform.c

@@ -55,6 +55,8 @@
 uint32_t NODE_ID           = 1;
 uint32_t WELLKNOWN_NODE_ID = 34;
 
+extern bool gPlatformPseudoResetWasRequested;
+
 #ifndef _WIN32
 int    gArgumentsCount = 0;
 char **gArguments      = NULL;
@@ -64,6 +66,12 @@ void PlatformInit(int argc, char *argv[])
 {
     char *endptr;
 
+    if (gPlatformPseudoResetWasRequested)
+    {
+        gPlatformPseudoResetWasRequested = false;
+        return;
+    }
+
     if (argc != 2)
     {
         exit(EXIT_FAILURE);
@@ -90,6 +98,11 @@ void PlatformInit(int argc, char *argv[])
     platformRandomInit();
 }
 
+bool PlatformPseudoResetWasRequested(void)
+{
+    return gPlatformPseudoResetWasRequested;
+}
+
 void PlatformDeinit(void)
 {
     platformRadioDeinit();

examples/platforms/posix/sim/platform-sim.c

@@ -52,6 +52,8 @@
 uint32_t NODE_ID           = 1;
 uint32_t WELLKNOWN_NODE_ID = 34;
 
+extern bool gPlatformPseudoResetWasRequested;
+
 int    gArgumentsCount = 0;
 char **gArguments      = NULL;
 
@@ -170,6 +172,12 @@ void PlatformInit(int argc, char *argv[])
 {
     char *endptr;
 
+    if (gPlatformPseudoResetWasRequested)
+    {
+        gPlatformPseudoResetWasRequested = false;
+        return;
+    }
+
     if (argc != 2)
     {
         exit(EXIT_FAILURE);
@@ -196,6 +204,11 @@ void PlatformInit(int argc, char *argv[])
     platformRandomInit();
 }
 
+bool PlatformPseudoResetWasRequested(void)
+{
+    return gPlatformPseudoResetWasRequested;
+}
+
 void PlatformDeinit(void)
 {
     close(sSockFd);

examples/platforms/samr21/platform.c

@@ -175,6 +175,11 @@ void PlatformInit(int argc, char *argv[])
     samr21RadioInit();
 }
 
+bool PlatformPseudoResetWasRequested(void)
+{
+    return false;
+}
+
 void PlatformDeinit(void)
 {
 }