ASoC: SDCA: Add basic SDCA class driver

Add a device level driver as the entry point for the class driver.
Additional auxiliary drivers will be registered to support each function
within the device. This driver will register those function drivers and
provide the device level functionality, such as monitoring bus
attach/detach, the device level register map, and the root for the IRQ
handling.

Co-developed-by: Maciej Strozek <mstrozek@opensource.cirrus.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/20251120153023.2105663-13-ckeepax@opensource.cirrus.com
Reviewed-by: Vinod Koul <vkoul@kernel.org>
Signed-off-by: Mark Brown <broonie@kernel.org>

include/linux/soundwire/sdw_registers.h

@@ -355,4 +355,6 @@
 /* Check the reserved and fixed bits in address */
 #define SDW_SDCA_VALID_CTL(reg) (((reg) & (GENMASK(31, 25) | BIT(18) | BIT(13))) == BIT(30))
 
+#define SDW_SDCA_MAX_REGISTER			0x47FFFFFF
+
 #endif /* __SDW_REGISTERS_H */

sound/soc/sdca/Kconfig

@@ -37,4 +37,14 @@ config SND_SOC_SDCA_FDL
 config SND_SOC_SDCA_OPTIONAL
 	def_tristate SND_SOC_SDCA || !SND_SOC_SDCA
 
+config SND_SOC_SDCA_CLASS
+	tristate "SDCA Class Driver"
+	depends on SND_SOC_SDCA
+	select SND_SOC_SDCA_FDL
+	select SND_SOC_SDCA_HID
+	select SND_SOC_SDCA_IRQ
+	help
+	  This option enables support for the SDCA Class driver which should
+	  support any class compliant SDCA part.
+
 endmenu

sound/soc/sdca/Makefile

@@ -6,4 +6,8 @@ snd-soc-sdca-$(CONFIG_SND_SOC_SDCA_HID) += sdca_hid.o
 snd-soc-sdca-$(CONFIG_SND_SOC_SDCA_IRQ) += sdca_interrupts.o
 snd-soc-sdca-$(CONFIG_SND_SOC_SDCA_FDL) += sdca_fdl.o
 
+snd-soc-sdca-class-y := sdca_class.o
+
 obj-$(CONFIG_SND_SOC_SDCA) += snd-soc-sdca.o
+
+obj-$(CONFIG_SND_SOC_SDCA_CLASS) += snd-soc-sdca-class.o

sound/soc/sdca/sdca_class.c

@@ -0,0 +1,304 @@
+// SPDX-License-Identifier: GPL-2.0
+// Copyright (C) 2025 Cirrus Logic, Inc. and
+//                    Cirrus Logic International Semiconductor Ltd.
+
+/*
+ * The MIPI SDCA specification is available for public downloads at
+ * https://www.mipi.org/mipi-sdca-v1-0-download
+ */
+
+#include <linux/device.h>
+#include <linux/err.h>
+#include <linux/mod_devicetable.h>
+#include <linux/module.h>
+#include <linux/pm.h>
+#include <linux/pm_runtime.h>
+#include <linux/regmap.h>
+#include <linux/soundwire/sdw.h>
+#include <linux/soundwire/sdw_registers.h>
+#include <linux/soundwire/sdw_type.h>
+#include <sound/sdca.h>
+#include <sound/sdca_function.h>
+#include <sound/sdca_interrupts.h>
+#include <sound/sdca_regmap.h>
+#include "sdca_class.h"
+
+#define CLASS_SDW_ATTACH_TIMEOUT_MS	5000
+
+static int class_read_prop(struct sdw_slave *sdw)
+{
+	struct sdw_slave_prop *prop = &sdw->prop;
+
+	sdw_slave_read_prop(sdw);
+
+	prop->use_domain_irq = true;
+	prop->scp_int1_mask = SDW_SCP_INT1_BUS_CLASH | SDW_SCP_INT1_PARITY |
+			      SDW_SCP_INT1_IMPL_DEF;
+
+	return 0;
+}
+
+static int class_sdw_update_status(struct sdw_slave *sdw, enum sdw_slave_status status)
+{
+	struct sdca_class_drv *drv = dev_get_drvdata(&sdw->dev);
+
+	switch (status) {
+	case SDW_SLAVE_ATTACHED:
+		dev_dbg(drv->dev, "device attach\n");
+
+		drv->attached = true;
+
+		complete(&drv->device_attach);
+		break;
+	case SDW_SLAVE_UNATTACHED:
+		dev_dbg(drv->dev, "device detach\n");
+
+		drv->attached = false;
+
+		reinit_completion(&drv->device_attach);
+		break;
+	default:
+		break;
+	}
+
+	return 0;
+}
+
+static const struct sdw_slave_ops class_sdw_ops = {
+	.read_prop	= class_read_prop,
+	.update_status	= class_sdw_update_status,
+};
+
+static void class_regmap_lock(void *data)
+{
+	struct mutex *lock = data;
+
+	mutex_lock(lock);
+}
+
+static void class_regmap_unlock(void *data)
+{
+	struct mutex *lock = data;
+
+	mutex_unlock(lock);
+}
+
+static int class_wait_for_attach(struct sdca_class_drv *drv)
+{
+	if (!drv->attached) {
+		unsigned long timeout = msecs_to_jiffies(CLASS_SDW_ATTACH_TIMEOUT_MS);
+		unsigned long time;
+
+		time = wait_for_completion_timeout(&drv->device_attach, timeout);
+		if (!time) {
+			dev_err(drv->dev, "timed out waiting for device re-attach\n");
+			return -ETIMEDOUT;
+		}
+	}
+
+	regcache_cache_only(drv->dev_regmap, false);
+
+	return 0;
+}
+
+static bool class_dev_regmap_volatile(struct device *dev, unsigned int reg)
+{
+	switch (reg) {
+	case SDW_SCP_SDCA_INTMASK1 ... SDW_SCP_SDCA_INTMASK4:
+		return false;
+	default:
+		return true;
+	}
+}
+
+static bool class_dev_regmap_precious(struct device *dev, unsigned int reg)
+{
+	switch (reg) {
+	case SDW_SCP_SDCA_INT1 ... SDW_SCP_SDCA_INT4:
+	case SDW_SCP_SDCA_INTMASK1 ... SDW_SCP_SDCA_INTMASK4:
+		return false;
+	default:
+		return true;
+	}
+}
+
+static const struct regmap_config class_dev_regmap_config = {
+	.name			= "sdca-device",
+	.reg_bits		= 32,
+	.val_bits		= 8,
+
+	.max_register		= SDW_SDCA_MAX_REGISTER,
+	.volatile_reg		= class_dev_regmap_volatile,
+	.precious_reg		= class_dev_regmap_precious,
+
+	.cache_type		= REGCACHE_MAPLE,
+
+	.lock			= class_regmap_lock,
+	.unlock			= class_regmap_unlock,
+};
+
+static void class_boot_work(struct work_struct *work)
+{
+	struct sdca_class_drv *drv = container_of(work,
+						  struct sdca_class_drv,
+						  boot_work);
+	int ret;
+
+	ret = class_wait_for_attach(drv);
+	if (ret)
+		goto err;
+
+	drv->irq_info = sdca_irq_allocate(drv->dev, drv->dev_regmap,
+					  drv->sdw->irq);
+	if (IS_ERR(drv->irq_info))
+		goto err;
+
+	ret = sdca_dev_register_functions(drv->sdw);
+	if (ret)
+		goto err;
+
+	dev_dbg(drv->dev, "boot work complete\n");
+
+	pm_runtime_mark_last_busy(drv->dev);
+	pm_runtime_put_autosuspend(drv->dev);
+
+	return;
+
+err:
+	pm_runtime_put_sync(drv->dev);
+}
+
+static void class_dev_remove(void *data)
+{
+	struct sdca_class_drv *drv = data;
+
+	cancel_work_sync(&drv->boot_work);
+
+	sdca_dev_unregister_functions(drv->sdw);
+}
+
+static int class_sdw_probe(struct sdw_slave *sdw, const struct sdw_device_id *id)
+{
+	struct device *dev = &sdw->dev;
+	struct sdca_device_data *data = &sdw->sdca_data;
+	struct regmap_config *dev_config;
+	struct sdca_class_drv *drv;
+	int ret;
+
+	sdca_lookup_swft(sdw);
+
+	drv = devm_kzalloc(dev, sizeof(*drv), GFP_KERNEL);
+	if (!drv)
+		return -ENOMEM;
+
+	dev_config = devm_kmemdup(dev, &class_dev_regmap_config,
+				  sizeof(*dev_config), GFP_KERNEL);
+	if (!dev_config)
+		return -ENOMEM;
+
+	drv->functions = devm_kcalloc(dev, data->num_functions,
+				      sizeof(*drv->functions),
+				      GFP_KERNEL);
+	if (!drv->functions)
+		return -ENOMEM;
+
+	drv->dev = dev;
+	drv->sdw = sdw;
+	mutex_init(&drv->regmap_lock);
+
+	dev_set_drvdata(drv->dev, drv);
+
+	INIT_WORK(&drv->boot_work, class_boot_work);
+	init_completion(&drv->device_attach);
+
+	dev_config->lock_arg = &drv->regmap_lock;
+
+	drv->dev_regmap = devm_regmap_init_sdw(sdw, dev_config);
+	if (IS_ERR(drv->dev_regmap))
+		return dev_err_probe(drv->dev, PTR_ERR(drv->dev_regmap),
+				     "failed to create device regmap\n");
+
+	regcache_cache_only(drv->dev_regmap, true);
+
+	pm_runtime_set_autosuspend_delay(dev, 250);
+	pm_runtime_use_autosuspend(dev);
+	pm_runtime_set_active(dev);
+	pm_runtime_get_noresume(dev);
+
+	ret = devm_pm_runtime_enable(dev);
+	if (ret)
+		return ret;
+
+	ret = devm_add_action_or_reset(dev, class_dev_remove, drv);
+	if (ret)
+		return ret;
+
+	queue_work(system_long_wq, &drv->boot_work);
+
+	return 0;
+}
+
+static int class_runtime_suspend(struct device *dev)
+{
+	struct sdca_class_drv *drv = dev_get_drvdata(dev);
+
+	/*
+	 * Whilst the driver doesn't power the chip down here, going into runtime
+	 * suspend lets the SoundWire bus power down, which means the driver
+	 * can't communicate with the device any more.
+	 */
+	regcache_cache_only(drv->dev_regmap, true);
+
+	return 0;
+}
+
+static int class_runtime_resume(struct device *dev)
+{
+	struct sdca_class_drv *drv = dev_get_drvdata(dev);
+	int ret;
+
+	ret = class_wait_for_attach(drv);
+	if (ret)
+		goto err;
+
+	regcache_mark_dirty(drv->dev_regmap);
+
+	ret = regcache_sync(drv->dev_regmap);
+	if (ret) {
+		dev_err(drv->dev, "failed to restore cache: %d\n", ret);
+		goto err;
+	}
+
+	return 0;
+
+err:
+	regcache_cache_only(drv->dev_regmap, true);
+
+	return ret;
+}
+
+static const struct dev_pm_ops class_pm_ops = {
+	RUNTIME_PM_OPS(class_runtime_suspend, class_runtime_resume, NULL)
+};
+
+static const struct sdw_device_id class_sdw_id[] = {
+	SDW_SLAVE_ENTRY(0x01FA, 0x4245, 0),
+	{}
+};
+MODULE_DEVICE_TABLE(sdw, class_sdw_id);
+
+static struct sdw_driver class_sdw_driver = {
+	.driver = {
+		.name		= "sdca_class",
+		.pm		= pm_ptr(&class_pm_ops),
+	},
+
+	.probe		= class_sdw_probe,
+	.id_table	= class_sdw_id,
+	.ops		= &class_sdw_ops,
+};
+module_sdw_driver(class_sdw_driver);
+
+MODULE_LICENSE("GPL");
+MODULE_DESCRIPTION("SDCA Class Driver");
+MODULE_IMPORT_NS("SND_SOC_SDCA");

sound/soc/sdca/sdca_class.h

@@ -0,0 +1,37 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+/*
+ * The MIPI SDCA specification is available for public downloads at
+ * https://www.mipi.org/mipi-sdca-v1-0-download
+ *
+ * Copyright (C) 2025 Cirrus Logic, Inc. and
+ *                    Cirrus Logic International Semiconductor Ltd.
+ */
+
+#ifndef __SDCA_CLASS_H__
+#define __SDCA_CLASS_H__
+
+#include <linux/completion.h>
+#include <linux/mutex.h>
+#include <linux/workqueue.h>
+
+struct device;
+struct regmap;
+struct sdw_slave;
+struct sdca_function_data;
+
+struct sdca_class_drv {
+	struct device *dev;
+	struct regmap *dev_regmap;
+	struct sdw_slave *sdw;
+
+	struct sdca_function_data *functions;
+	struct sdca_interrupt_info *irq_info;
+
+	struct mutex regmap_lock;
+	struct work_struct boot_work;
+	struct completion device_attach;
+
+	bool attached;
+};
+
+#endif /* __SDCA_CLASS_H__ */