drivers/syslog: Implement RTT based log channel

Signed-off-by: Xiang Xiao <xiaoxiang@xiaomi.com>

include/nuttx/syslog/syslog_rtt.h

@@ -0,0 +1,54 @@
+/****************************************************************************
+ * include/nuttx/syslog/syslog_rtt.h
+ *
+ * Licensed to the Apache Software Foundation (ASF) under one or more
+ * contributor license agreements.  See the NOTICE file distributed with
+ * this work for additional information regarding copyright ownership.  The
+ * ASF licenses this file to you under the Apache License, Version 2.0 (the
+ * "License"); you may not use this file except in compliance with the
+ * License.  You may obtain a copy of the License at
+ *
+ *   http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
+ * WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.  See the
+ * License for the specific language governing permissions and limitations
+ * under the License.
+ *
+ ****************************************************************************/
+
+#ifndef __INCLUDE_NUTTX_SYSLOG_SYSLOG_RTT_H
+#define __INCLUDE_NUTTX_SYSLOG_SYSLOG_RTT_H
+
+/****************************************************************************
+ * Included Files
+ ****************************************************************************/
+
+#include <nuttx/config.h>
+#include <nuttx/syslog/syslog.h>
+
+/****************************************************************************
+ * Public Function Prototypes
+ ****************************************************************************/
+
+#ifdef __cplusplus
+#define EXTERN extern "C"
+extern "C"
+{
+#else
+#define EXTERN extern
+#endif
+
+#ifdef CONFIG_SYSLOG_RTT
+int syslog_rtt_putc(FAR struct syslog_channel_s *channel, int ch);
+ssize_t syslog_rtt_write(FAR struct syslog_channel_s *channel,
+                         FAR const char *buffer, size_t buflen);
+#endif
+
+#undef EXTERN
+#ifdef __cplusplus
+}
+#endif
+
+#endif /* __INCLUDE_NUTTX_SYSLOG_SYSLOG_RTT_H */