CMake: greentea: Fix io issue with greentea-client

The stdio implementation of the standalone greentea-client wasn't
streaming "KiVi protocol" messages through the serial IO. Separate out
the existing implementation for greentea-client that uses
mbed_retarget.h's `read` and `write` functions so greentea tests
continue to work with the standalone client.

The IO fixture is shared between the "legacy" embedded greentea-client
and the newer standalone client.

features/CMakeLists.txt

@@ -11,3 +11,4 @@ add_subdirectory(frameworks/COMPONENT_FPGA_CI_TEST_SHIELD)
 add_subdirectory(frameworks/mbed-client-cli)
 add_subdirectory(frameworks/unity)
 add_subdirectory(frameworks/utest)
+add_subdirectory(frameworks/mbed-greentea-io)

features/frameworks/greentea-client/source/greentea_test_env.cpp

@@ -239,22 +239,6 @@ static void greentea_write_postamble()
     greentea_putc('\n');
 }
 
-/**
- * \brief Write a string to the serial port
- *
- *        This function writes a '\0' terminated string from the target
- *        to the host. It writes directly to the serial port using the
- *        the write() method.
- *
- * \param str - string value
- *
- */
-void greentea_write_string(const char *str)
-{
-    write(STDOUT_FILENO, str, strlen(str));
-}
-
-
 /**
  * \brief Write an int to the serial port
  *
@@ -536,40 +520,6 @@ enum Token {
     tok_string = -5
 };
 
-/**
- * \brief Read character from stream of data
- *
- *        Closure for default "get character" function.
- *        This function is used to read characters from the stream
- *        (default is serial port RX). Key-value protocol tokenizer
- *        will build stream of tokes used by key-value protocol to
- *        detect valid messages.
- *
- *        If EOF is received parser finishes parsing and stops. In
- *        situation where we have serial port stream of data parsing
- *        goes forever.
- *
- * \return Next character from the stream or EOF if stream has ended.
- *
- */
-extern "C" int greentea_getc() {
-    uint8_t c;
-    read(STDOUT_FILENO, &c, 1);
-    return c;
-}
-
-
-/**
- * \brief Write character from stream of data
- *
- * \return The number of bytes written
- *
- */
-extern "C" void greentea_putc(int c) {
-    uint8_t _c = c;
-    write(STDOUT_FILENO, &_c, 1);
-}
-
 /**
  * \brief parse input string for key-value pairs: {{key;value}}
  *        This function should replace scanf() used to

features/frameworks/mbed-greentea-io/CMakeLists.txt

@@ -0,0 +1,6 @@
+# Copyright (c) 2021 ARM Limited. All rights reserved.
+# SPDX-License-Identifier: Apache-2.0
+
+add_library(mbed-greentea-io INTERFACE)
+target_sources(mbed-greentea-io INTERFACE mbed_io.cpp)
+target_link_libraries(mbed-greentea-io INTERFACE mbed-core)

features/frameworks/mbed-greentea-io/mbed_io.cpp

@@ -0,0 +1,37 @@
+/*
+ * Copyright (c) 2021, ARM Limited, All Rights Reserved
+ * SPDX-License-Identifier: Apache-2.0
+ *
+ * Licensed 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.
+ */
+#include <cstdint>
+#include <cstring>
+#include "platform/mbed_retarget.h"
+
+extern "C" void greentea_write_string(const char *str)
+{
+    write(STDOUT_FILENO, str, strlen(str));
+}
+
+extern "C" int greentea_getc()
+{
+    uint8_t c;
+    read(STDOUT_FILENO, &c, 1);
+    return c;
+}
+
+extern "C" void greentea_putc(int c)
+{
+    uint8_t _c = c;
+    write(STDOUT_FILENO, &_c, 1);
+}

tools/cmake/mbed_greentea.cmake

@@ -61,7 +61,7 @@ macro(mbed_greentea_add_test)
         list(APPEND MBED_GREENTEA_TEST_REQUIRED_LIBS mbed-os)
     endif()
 
-    list(APPEND MBED_GREENTEA_TEST_REQUIRED_LIBS greentea::client mbed-unity mbed-utest)
+    list(APPEND MBED_GREENTEA_TEST_REQUIRED_LIBS greentea::client_userio mbed-greentea-io mbed-unity mbed-utest)
 
     target_link_libraries(${MBED_GREENTEA_TEST_NAME}
         PRIVATE