[scons] Add ITM convenience wrapper

tools/build_script_generator/scons/module.lb

@@ -108,6 +108,7 @@ def build(env):
         "gdb",
         "build_target",
         "artifact",
+        "log_itm",
     }
     if has_xpcc_generator:
         tools.add("xpcc_generator")

tools/build_script_generator/scons/module.md

@@ -165,6 +165,16 @@ argument.
 See the `:platform:fault` module for details how to receive the coredump data.
 
 
+#### scons itm
+
+Configures OpenOCD in tracing mode to output ITM channel 0 on SWO pin and
+displays the serial output stream.
+(\* *only Cortex-M targets*)
+
+See the `:platform:itm` module for details how to use the ITM as a logging
+output.
+
+
 #### scons symbols
 
 Dumps the symbol table for your executable.

tools/build_script_generator/scons/resources/build_target.py.in

@@ -38,6 +38,7 @@ def build_target(env, sources):
 	env.Alias("program", env.OpenOcd(program, commands=["modm_program $SOURCE"]))
 	env.Alias("bmp", env.BlackMagicProbe(program))
 	%% endif
+	env.Alias("itm", env.OpenOcdItm())
 	env.Alias("gdb", env.OpenOcdGdb(program))
 	env.Alias("postmortem", env.PostMortemGdb(program))
     %% elif core.startswith("avr")

tools/build_script_generator/scons/site_tools/log_itm.py

@@ -0,0 +1,65 @@
+#!/usr/bin/env python2
+# -*- coding: utf-8 -*-
+#
+# Copyright (c) 2019, Niklas Hauser
+#
+# This file is part of the modm project.
+#
+# This Source Code Form is subject to the terms of the Mozilla Public
+# License, v. 2.0. If a copy of the MPL was not distributed with this
+# file, You can obtain one at http://mozilla.org/MPL/2.0/.
+# -----------------------------------------------------------------------------
+
+import os
+from SCons.Script import *
+import subprocess
+import tempfile
+import signal
+
+# -----------------------------------------------------------------------------
+def run_openocd_itm(target, source, env):
+    # Provide additional search paths via the OPENOCD_SCRIPTS environment variable
+    # See http://openocd.org/doc/html/Running.html
+    env["ENV"]["OPENOCD_SCRIPTS"] = os.environ.get("OPENOCD_SCRIPTS", "")
+    search = env.get("MODM_OPENOCD_SEARCHDIRS", [])
+    config = env.get("MODM_OPENOCD_CONFIGFILES", [])
+    openocdcmd = '{} {}'.format(
+            " ".join(map('-s "{}"'.format, map(env.subst, search))),
+            " ".join(map('-f "{}"'.format, map(env.subst, config))))
+
+    fcpu = ARGUMENTS.get("fcpu", None)
+    if fcpu is None:
+        print("\n    You must provide the current CPU/HCLK frequency as `fcpu={Hz}` argument!\n")
+        return -1
+    baudrate = ARGUMENTS.get("baudrate", "")
+
+    with tempfile.NamedTemporaryFile() as tmpfile:
+        itm_config = "modm_itm_log {} {} {}".format(tmpfile.name, fcpu, baudrate)
+        openocdcmd += ' -c "{}"'.format(itm_config)
+        openocdcmd = '-c "log_output /dev/null"' + openocdcmd
+
+        # Start OpenOCD in the background
+        openocd = subprocess.Popen('openocd ' + openocdcmd, cwd=os.getcwd(), shell=True)
+        # Start a blocking call to monitor the log file
+        subprocess.call("tail -f {}".format(tmpfile.name), cwd=os.getcwd(), shell=True)
+        # kill OpenOCD process when Ctrl-C happened
+        os.killpg(os.getpgid(openocd.pid), signal.SIGTERM)
+
+    return 0
+
+def openocd_itm(env, alias="openocd_itm"):
+    action = Action(run_openocd_itm, cmdstr="$OPENOCDITMSTR")
+    return env.AlwaysBuild(env.Alias(alias, None, action))
+
+# -----------------------------------------------------------------------------
+def generate(env, **kw):
+    env["OPENOCD"] = "openocd"
+    if ARGUMENTS.get('verbose') != '1':
+        env["OPENOCDITMSTR"] = ("{0}.----OpenOCD--> {1}Single Wire Viewer\n"
+                                "{0}'------SWO----- {2}$CONFIG_DEVICE_NAME{3}"
+                                .format("\033[;0;32m", "\033[;0;33m", "\033[;1;33m", "\033[;0;0m"))
+
+    env.AddMethod(openocd_itm, "OpenOcdItm")
+
+def exists(env):
+    return env.Detect("openocd") and env.Detect("tail")