ASoC: SDCA: add function devices

Use the auxiliary bus to register/unregister subdevices for each
function. Each function will be handled with a separate driver,
matched using a name.

If a vendor wants to override a specific function driver, they could
use a custom name to match with a custom function driver.

Signed-off-by: Pierre-Louis Bossart <pierre-louis.bossart@linux.intel.com>
Tested-by: Bard Liao <yung-chuan.liao@linux.intel.com>
Reviewed-by: Maciej Strozek <mstrozek@opensource.cirrus.com>
Reviewed-by: Peter Ujfalusi <peter.ujfalusi@linux.intel.com>
Tested-by: Richard Fitzgerald <rf@opensource.cirrus.com>
Signed-off-by: Charles Keepax <ckeepax@opensource.cirrus.com>
Link: https://patch.msgid.link/20251120153023.2105663-12-ckeepax@opensource.cirrus.com
Reviewed-by: Vinod Koul <vkoul@kernel.org>
Signed-off-by: Mark Brown <broonie@kernel.org>

1 files changed, 117 insertions, 0 deletions

diff --git a/sound/soc/sdca/sdca_function_device.c b/sound/soc/sdca/sdca_function_device.c
new file mode 100644
index 000000000000..91c49d7389db
--- /dev/null
+++ b/sound/soc/sdca/sdca_function_device.c
@@ -0,0 +1,117 @@
+// SPDX-License-Identifier: (GPL-2.0 OR BSD-3-Clause)
+// Copyright(c) 2024 Intel Corporation.
+
+/*
+ * SDCA Function Device management
+ */
+
+#include <linux/acpi.h>
+#include <linux/module.h>
+#include <linux/auxiliary_bus.h>
+#include <linux/soundwire/sdw.h>
+#include <sound/sdca.h>
+#include <sound/sdca_function.h>
+#include "sdca_function_device.h"
+
+/*
+ * A SoundWire device can have multiple SDCA functions identified by
+ * their type and ADR. there can be multiple SoundWire devices per
+ * link, or multiple devices spread across multiple links. An IDA is
+ * required to identify each instance.
+ */
+static DEFINE_IDA(sdca_function_ida);
+
+static void sdca_dev_release(struct device *dev)
+{
+	struct auxiliary_device *auxdev = to_auxiliary_dev(dev);
+	struct sdca_dev *sdev = auxiliary_dev_to_sdca_dev(auxdev);
+
+	ida_free(&sdca_function_ida, auxdev->id);
+	kfree(sdev);
+}
+
+/* alloc, init and add link devices */
+static struct sdca_dev *sdca_dev_register(struct device *parent,
+					  struct sdca_function_desc *function_desc)
+{
+	struct sdca_dev *sdev;
+	struct auxiliary_device *auxdev;
+	int ret;
+	int rc;
+
+	sdev = kzalloc(sizeof(*sdev), GFP_KERNEL);
+	if (!sdev)
+		return ERR_PTR(-ENOMEM);
+
+	auxdev = &sdev->auxdev;
+	auxdev->name = function_desc->name;
+	auxdev->dev.parent = parent;
+	auxdev->dev.fwnode = function_desc->node;
+	auxdev->dev.release = sdca_dev_release;
+
+	sdev->function.desc = function_desc;
+
+	rc = ida_alloc(&sdca_function_ida, GFP_KERNEL);
+	if (rc < 0) {
+		kfree(sdev);
+		return ERR_PTR(rc);
+	}
+	auxdev->id = rc;
+
+	/* now follow the two-step init/add sequence */
+	ret = auxiliary_device_init(auxdev);
+	if (ret < 0) {
+		dev_err(parent, "failed to initialize SDCA function dev %s\n",
+			function_desc->name);
+		ida_free(&sdca_function_ida, auxdev->id);
+		kfree(sdev);
+		return ERR_PTR(ret);
+	}
+
+	ret = auxiliary_device_add(auxdev);
+	if (ret < 0) {
+		dev_err(parent, "failed to add SDCA function dev %s\n",
+			sdev->auxdev.name);
+		/* sdev will be freed with the put_device() and .release sequence */
+		auxiliary_device_uninit(&sdev->auxdev);
+		return ERR_PTR(ret);
+	}
+
+	return sdev;
+}
+
+static void sdca_dev_unregister(struct sdca_dev *sdev)
+{
+	auxiliary_device_delete(&sdev->auxdev);
+	auxiliary_device_uninit(&sdev->auxdev);
+}
+
+int sdca_dev_register_functions(struct sdw_slave *slave)
+{
+	struct sdca_device_data *sdca_data = &slave->sdca_data;
+	int i;
+
+	for (i = 0; i < sdca_data->num_functions; i++) {
+		struct sdca_dev *func_dev;
+
+		func_dev = sdca_dev_register(&slave->dev,
+					     &sdca_data->function[i]);
+		if (!func_dev)
+			return -ENODEV;
+
+		sdca_data->function[i].func_dev = func_dev;
+	}
+
+	return 0;
+}
+EXPORT_SYMBOL_NS(sdca_dev_register_functions, "SND_SOC_SDCA");
+
+void sdca_dev_unregister_functions(struct sdw_slave *slave)
+{
+	struct sdca_device_data *sdca_data = &slave->sdca_data;
+	int i;
+
+	for (i = 0; i < sdca_data->num_functions; i++)
+		sdca_dev_unregister(sdca_data->function[i].func_dev);
+}
+EXPORT_SYMBOL_NS(sdca_dev_unregister_functions, "SND_SOC_SDCA");