debug_stream: Add text message record type and a ds_msg() to send them

Add new record type for simple text messages to the debug stream
protocol and a function for sending the messages. This functionality
is for debugging purposes when for some reason or another the usual
methods do not work. ds_msg() can be used like printf and the printed
messages can be displayed on host side with debug_stream.py.

Signed-off-by: Jyri Sarha <jyri.sarha@linux.intel.com>

Author: Jyri Sarha

src/debug/debug_stream/CMakeLists.txt

@@ -3,3 +3,5 @@
 add_local_sources_ifdef(CONFIG_SOF_DEBUG_STREAM_SLOT sof debug_stream_slot.c)
 
 add_local_sources_ifdef(CONFIG_SOF_DEBUG_STREAM_THREAD_INFO sof debug_stream_thread_info.c)
+
+add_local_sources_ifdef(CONFIG_SOF_DEBUG_STREAM_TEXT_MSG sof debug_stream_text_msg.c)

src/debug/debug_stream/Kconfig

@@ -44,4 +44,13 @@ config SOF_DEBUG_STREAM_THREAD_INFO_INTERVAL
 	  Decides how often thread info runs and checks execution cycle
 	  statistics and stack usage.
 
+config SOF_DEBUG_STREAM_TEXT_MSG
+	bool "Enable text message sending through Debug-Stream"
+	help
+	  Enable debug message sending over debug stream. To use this
+	  feature one only needs to enable debug stream with this
+	  config option and print the debug messages with
+	  ds_msg(). See include/user/debug_stream_text_msg.h for
+	  prototype.
+
 endif

src/debug/debug_stream/debug_stream_text_msg.c

@@ -0,0 +1,37 @@
+// SPDX-License-Identifier: BSD-3-Clause
+//
+// Copyright(c) 2024 Intel Corporation.
+
+#include <sys/types.h>
+#include <stdarg.h>
+#include <stdio.h>
+#include <soc.h>
+#include <adsp_debug_window.h>
+#include <sof/common.h>
+
+#include <user/debug_stream_text_msg.h>
+
+void ds_msg(const char *format, ...)
+{
+	va_list args;
+	struct {
+		struct debug_stream_text_msg msg;
+		char text[128];
+	} __packed buf = { 0 };
+	ssize_t len;
+
+	va_start(args, format);
+	len = vsnprintf(buf.text, sizeof(buf.text), format, args);
+	va_end(args);
+
+	if (len < 0)
+		return;
+	len = MIN(len, sizeof(buf.text));
+
+	buf.msg.hdr.id = DEBUG_STREAM_RECORD_ID_TEXT_MSG;
+	buf.msg.hdr.size_words = SOF_DIV_ROUND_UP(sizeof(buf.msg) + len,
+						  sizeof(buf.msg.hdr.data[0]));
+	debug_stream_slot_send_record(&buf.msg.hdr);
+}
+EXPORT_SYMBOL(ds_msg);
+

src/include/user/debug_stream.h

@@ -48,5 +48,6 @@ struct debug_stream_record {
 /* Debug Stream record identifiers */
 #define DEBUG_STREAM_RECORD_ID_UNINITIALIZED	0 /* invalid record marker */
 #define DEBUG_STREAM_RECORD_ID_THREAD_INFO	1 /* Thread info record */
+#define DEBUG_STREAM_RECORD_ID_TEXT_MSG		2 /* Text message */
 
 #endif /* __SOC_DEBUG_STREAM_H__ */

src/include/user/debug_stream_text_msg.h

@@ -0,0 +1,25 @@
+/* SPDX-License-Identifier: BSD-3-Clause
+ *
+ * Copyright(c) 2024 Intel Corporation.
+ */
+
+#ifndef __SOC_DEBUG_STREAM_TEXT_MSG_H__
+#define __SOC_DEBUG_STREAM_TEXT_MSG_H__
+
+#include <user/debug_stream_slot.h>
+
+/*
+ * Debug Stream text message.
+ */
+struct debug_stream_text_msg {
+	struct debug_stream_record hdr;
+	char msg[];
+} __packed;
+
+/*
+ * To send debug messages over debug stream. Enable
+ * CONFIG_SOF_DEBUG_STREAM_TEXT_MSG to enable this function.
+ */
+void ds_msg(const char *format, ...);
+
+#endif /*  __SOC_DEBUG_STREAM_TEXT_MSG_H__ */