[diag] add gpio diag command support (#8316)

include/openthread/diag.h

@@ -85,8 +85,13 @@ otError otDiagProcessCmd(otInstance *aInstance,
  * @param[out]  aOutput         The diagnostics execution result.
  * @param[in]   aOutputMaxLen   The output buffer size.
  *
+ * @retval  OT_ERROR_NONE               The command is successfully process.
+ * @retval  OT_ERROR_INVALID_ARGS       The command is supported but invalid arguments provided.
+ * @retval  OT_ERROR_NOT_IMPLEMENTED    The command is not supported.
+ * @retval  OT_ERROR_NO_BUFS            The command string is too long.
+ *
  */
-void otDiagProcessCmdLine(otInstance *aInstance, const char *aString, char *aOutput, size_t aOutputMaxLen);
+otError otDiagProcessCmdLine(otInstance *aInstance, const char *aString, char *aOutput, size_t aOutputMaxLen);
 
 /**
  * This function indicates whether or not the factory diagnostics mode is enabled.

include/openthread/instance.h

@@ -53,7 +53,7 @@ extern "C" {
  * @note This number versions both OpenThread platform and user APIs.
  *
  */
-#define OPENTHREAD_API_VERSION (256)
+#define OPENTHREAD_API_VERSION (257)
 
 /**
  * @addtogroup api-instance

include/openthread/platform/diag.h

@@ -129,6 +129,32 @@ void otPlatDiagRadioReceived(otInstance *aInstance, otRadioFrame *aFrame, otErro
  */
 void otPlatDiagAlarmCallback(otInstance *aInstance);
 
+/**
+ * This function sets the gpio value.
+ *
+ * @param[in]  aGpio   The gpio number.
+ * @param[in]  aValue  true to set the gpio to high level, or false otherwise.
+ *
+ * @retval OT_ERROR_NONE             Successfully set the gpio.
+ * @retval OT_ERROR_INVALID_ARGS     @p aGpio is not supported.
+ * @retval OT_ERROR_NOT_IMPLEMENTED  This function is not implemented on the platform.
+ *
+ */
+otError otPlatDiagGpioSet(uint32_t aGpio, bool aValue);
+
+/**
+ * This function gets the gpio value.
+ *
+ * @param[in]   aGpio   The gpio number.
+ * @param[out]  aValue  A pointer where to put gpio value.
+ *
+ * @retval OT_ERROR_NONE             Successfully got the gpio value.
+ * @retval OT_ERROR_INVALID_ARGS     @p aGpio is not supported or @p aValue is NULL.
+ * @retval OT_ERROR_NOT_IMPLEMENTED  This function is not implemented on the platform.
+ *
+ */
+otError otPlatDiagGpioGet(uint32_t aGpio, bool *aValue);
+
 /**
  * @}
  *