ASoC: SOF: IPC4: Simple debugfs file for debug-stream debug window slot

The "debug-stream" debugfs file simply maps the debug-stream debug slot as
a debugfs file. The decoding is left to user-space tools. For details on
the debug-stream encodeing, see src/debug/debug_stream/debug_stream_slot.h
in SOF sources [1].

[1] https://github.com/thesofproject/sof

Signed-off-by: Jyri Sarha <[email protected]>

Author: Jyri Sarha

sound/soc/sof/Makefile

@@ -11,7 +11,7 @@ snd-sof-y +=	ipc3.o ipc3-loader.o ipc3-topology.o ipc3-control.o ipc3-pcm.o\
 endif
 ifneq ($(CONFIG_SND_SOC_SOF_IPC4),)
 snd-sof-y += ipc4.o ipc4-loader.o ipc4-topology.o ipc4-control.o ipc4-pcm.o\
-		ipc4-mtrace.o ipc4-telemetry.o
+		ipc4-mtrace.o ipc4-telemetry.o ipc4-debug-stream.o
 endif
 
 # SOF client support

sound/soc/sof/ipc4-debug-stream.c

@@ -0,0 +1,80 @@
+// SPDX-License-Identifier: (GPL-2.0-only OR BSD-3-Clause)
+//
+// This file is provided under a dual BSD/GPLv2 license.  When using or
+// redistributing this file, you may do so under either license.
+//
+// Copyright(c) 2024 Intel Corporation. All rights reserved.
+//
+
+#include <linux/debugfs.h>
+#include <linux/io.h>
+#include <linux/pm_runtime.h>
+#include <sound/sof/debug.h>
+#include <sound/sof/ipc4/header.h>
+#include "sof-priv.h"
+#include "ops.h"
+#include "ipc4-debug-stream.h"
+#include "ipc4-priv.h"
+
+static ssize_t sof_debug_stream_entry_read(struct file *file, char __user *buffer,
+					size_t count, loff_t *ppos)
+{
+	struct snd_sof_dfsentry *dfse = file->private_data;
+	struct snd_sof_dev *sdev = dfse->sdev;
+	u32 type = SOF_IPC4_DEBUG_SLOT_DEBUG_STREAM;
+	loff_t pos = *ppos;
+	size_t size_ret;
+	u32 offset;
+	u8 *buf;
+
+	if (pos < 0)
+		return -EINVAL;
+	if (pos >= SOF_IPC4_DEBUG_SLOT_SIZE || !count)
+		return 0;
+	if (count > SOF_IPC4_DEBUG_SLOT_SIZE - pos)
+		count = SOF_IPC4_DEBUG_SLOT_SIZE - pos;
+
+	offset = sof_ipc4_find_debug_slot_offset_by_type(sdev, type);
+	if (!offset)
+		return -EFAULT;
+
+	buf = kzalloc(SOF_IPC4_DEBUG_SLOT_SIZE, GFP_KERNEL);
+	if (!buf)
+		return -ENOMEM;
+
+	sof_mailbox_read(sdev, offset, buf, SOF_IPC4_DEBUG_SLOT_SIZE);
+	size_ret = copy_to_user(buffer, buf + pos, count);
+	if (size_ret) {
+		kfree(buf);
+		return -EFAULT;
+	}
+
+	*ppos = pos + count;
+	kfree(buf);
+
+	return count;
+}
+
+static const struct file_operations sof_debug_stream_fops = {
+	.open = simple_open,
+	.read = sof_debug_stream_entry_read,
+	.llseek = default_llseek,
+};
+
+void sof_ipc4_create_debug_stream_debugfs_node(struct snd_sof_dev *sdev)
+{
+	struct snd_sof_dfsentry *dfse;
+
+	dfse = devm_kzalloc(sdev->dev, sizeof(*dfse), GFP_KERNEL);
+	if (!dfse)
+		return;
+
+	dfse->type = SOF_DFSENTRY_TYPE_IOMEM;
+	dfse->size = SOF_IPC4_DEBUG_SLOT_SIZE;
+	dfse->access_type = SOF_DEBUGFS_ACCESS_ALWAYS;
+	dfse->sdev = sdev;
+
+	list_add(&dfse->list, &sdev->dfsentry_list);
+
+	debugfs_create_file("debug_stream", 0444, sdev->debugfs_root, dfse, &sof_debug_stream_fops);
+}

sound/soc/sof/ipc4-debug-stream.h

@@ -0,0 +1,14 @@
+/* SPDX-License-Identifier: (GPL-2.0-only OR BSD-3-Clause) */
+/*
+ * This file is provided under a dual BSD/GPLv2 license.  When using or
+ * redistributing this file, you may do so under either license.
+ *
+ * Copyright(c) 2024 Intel Corporation. All rights reserved.
+ */
+
+#ifndef __SOUND_SOC_SOF_IPC4_DEBUG_STREAM_H
+#define __SOUND_SOC_SOF_IPC4_DEBUG_STREAM_H
+
+void sof_ipc4_create_debug_stream_debugfs_node(struct snd_sof_dev *sdev);
+
+#endif

sound/soc/sof/ipc4.c

@@ -16,6 +16,7 @@
 #include "ipc4-fw-reg.h"
 #include "ipc4-priv.h"
 #include "ipc4-telemetry.h"
+#include "ipc4-debug-stream.h"
 #include "ops.h"
 
 static const struct sof_ipc4_fw_status {
@@ -582,6 +583,8 @@ static int ipc4_fw_ready(struct snd_sof_dev *sdev, struct sof_ipc4_msg *ipc4_msg
 
 	sof_ipc4_create_exception_debugfs_node(sdev);
 
+	sof_ipc4_create_debug_stream_debugfs_node(sdev);
+
 	return sof_ipc4_init_msg_memory(sdev);
 }