drivers: dai: Add virtual DAI driver

Introduce a virtual DAI driver for prototyping, loopback, and testing
without requiring physical DAI hardware.

This includes:
- Initial virtual DAI implementation (logging only)
- DTS binding (dai-virtual.yaml)
- Kconfig and CMake updates
- i.MX8M DTS integration

Signed-off-by: Suraj Sonawane <[email protected]>

Author: SurajSonawane2415

drivers/dai/CMakeLists.txt

@@ -7,3 +7,4 @@ add_subdirectory_ifdef(CONFIG_DAI_INTEL_HDA intel/hda)
 add_subdirectory_ifdef(CONFIG_DAI_NXP_SAI nxp/sai)
 add_subdirectory_ifdef(CONFIG_DAI_NXP_ESAI nxp/esai)
 add_subdirectory_ifdef(CONFIG_DAI_NXP_MICFIL nxp/micfil)
+add_subdirectory_ifdef(CONFIG_DAI_VIRTUAL virtual)

drivers/dai/Kconfig

@@ -32,5 +32,6 @@ source "drivers/dai/intel/hda/Kconfig.hda"
 source "drivers/dai/nxp/sai/Kconfig.sai"
 source "drivers/dai/nxp/esai/Kconfig.esai"
 source "drivers/dai/nxp/micfil/Kconfig.micfil"
+source "drivers/dai/virtual/Kconfig.virtual"
 
 endif # DAI

drivers/dai/virtual/CMakeLists.txt

@@ -0,0 +1,5 @@
+# Copyright (c) 2025 Suraj Sonawane <[email protected]>
+# SPDX-License-Identifier: Apache-2.0
+
+zephyr_library()
+zephyr_library_sources_ifdef(CONFIG_DAI_VIRTUAL	virtual_dai.c)

drivers/dai/virtual/Kconfig.virtual

@@ -0,0 +1,10 @@
+# Copyright (c) 2025, Suraj Sonawane <[email protected]@gmail.com>
+# SPDX-License-Identifier: Apache-2.0
+
+config DAI_VIRTUAL
+	bool "Virtual DAI driver"
+	help
+	  Select this to enable support for a Virtual DAI driver.
+	  This driver is useful for debugging and rapid prototyping without
+	  real hardware. It simulates audio input/output behavior in software
+	  and is useful in memory-to-memory pipelines.

drivers/dai/virtual/virtual_dai.c

@@ -0,0 +1,112 @@
+/*
+ * Copyright (c) 2025 Suraj Sonawane <[email protected]>
+ *
+ * SPDX-License-Identifier: Apache-2.0
+ */
+
+#include <zephyr/kernel.h>
+#include <zephyr/logging/log.h>
+#include <zephyr/drivers/dai.h>
+#include <zephyr/pm/device_runtime.h>
+#include <string.h>
+
+#define DT_DRV_COMPAT virtual_dai
+LOG_MODULE_REGISTER(virtual_dai, CONFIG_DAI_LOG_LEVEL);
+
+struct virtual_dai_data {
+	struct dai_config cfg;
+};
+
+static int virtual_dai_probe(const struct device *dev)
+{
+	return 0;
+}
+
+static int virtual_dai_remove(const struct device *dev)
+{
+	return 0;
+}
+
+static int virtual_dai_config_set(const struct device *dev,
+			  const struct dai_config *cfg,
+			  const void *bespoke_data)
+{
+	if (cfg->type != DAI_VIRTUAL) {
+		LOG_ERR("wrong DAI type: %d", cfg->type);
+		return -EINVAL;
+	}
+
+	return 0;
+}
+
+static int virtual_dai_config_get(const struct device *dev,
+			  struct dai_config *cfg,
+			  enum dai_dir dir)
+{
+	struct virtual_dai_data *data = dev->data;
+
+	/* dump content of the DAI configuration */
+	memcpy(cfg, &data->cfg, sizeof(*cfg));
+
+	return 0;
+}
+
+static const struct dai_properties *
+virtual_dai_get_properties(const struct device *dev, enum dai_dir dir, int stream_id)
+{
+	return NULL;
+}
+
+static int virtual_dai_trigger(const struct device *dev,
+		       enum dai_dir dir,
+		       enum dai_trigger_cmd cmd)
+{
+	switch (cmd) {
+	case DAI_TRIGGER_START:
+		LOG_DBG("virtual_dai: START (dir=%d)", dir);
+		return 0;
+	case DAI_TRIGGER_STOP:
+		LOG_DBG("virtual_dai: STOP (dir=%d)", dir);
+		return 0;
+	case DAI_TRIGGER_PAUSE:
+		LOG_DBG("virtual_dai: PAUSE (dir=%d)", dir);
+		return 0;
+	case DAI_TRIGGER_PRE_START:
+	case DAI_TRIGGER_COPY:
+		LOG_DBG("virtual_dai: DAI_TRIGGER_COPY");
+		return 0;
+	default:
+		LOG_WRN("virtual_dai: Unknown trigger %d", cmd);
+		return -EINVAL;
+	}
+
+	CODE_UNREACHABLE;
+}
+
+static DEVICE_API(dai, virtual_dai_api) = {
+	.probe = virtual_dai_probe,
+	.remove = virtual_dai_remove,
+	.config_set = virtual_dai_config_set,
+	.config_get = virtual_dai_config_get,
+	.get_properties = virtual_dai_get_properties,
+	.trigger = virtual_dai_trigger,
+};
+
+static int virtual_dai_init(const struct device *dev)
+{
+	return 0;
+}
+
+#define VIRTUAL_DAI_INIT(inst) \
+static struct virtual_dai_data virtual_dai_data_##inst = {					\
+	.cfg.type = DAI_VIRTUAL,						\
+	.cfg.dai_index = DT_INST_PROP_OR(inst, dai_index, 0),			\
+};										\
+										\
+DEVICE_DT_INST_DEFINE(inst, \
+		      &virtual_dai_init, NULL, \
+		      &virtual_dai_data_##inst, NULL, \
+		      POST_KERNEL, CONFIG_DAI_INIT_PRIORITY, \
+		      &virtual_dai_api);
+
+DT_INST_FOREACH_STATUS_OKAY(VIRTUAL_DAI_INIT);

dts/bindings/dai/dai-virtual.yaml

@@ -0,0 +1,18 @@
+# Copyright (c) 2025 Suraj Sonawane <[email protected]>
+# SPDX-License-Identifier: Apache-2.0
+
+title: Zephyr binding for a Virtual DAI (Digital Audio Interface)
+
+description: |
+  This DAI is not connected to real hardware and is used for software-only
+  audio routing or testing within SOF + Zephyr systems.
+
+compatible: "virtual_dai"
+
+include: base.yaml
+
+properties:
+  dai-index:
+    type: int
+    description: |
+      DAI index used to identify this virtual DAI in IPC and topology.

include/zephyr/drivers/dai.h

@@ -116,6 +116,7 @@ enum dai_type {
 	DAI_INTEL_HDA_NHLT,	/**< nhlt Intel HD/A */
 	DAI_INTEL_ALH_NHLT,	/**< nhlt Intel ALH */
 	DAI_IMX_MICFIL,		/**< i.MX PDM MICFIL */
+	DAI_VIRTUAL,		/**< Virtual DAI*/
 };
 
 /**