soundwire: Add SoundWire bus type

This adds the base SoundWire bus type, bus and driver registration.
along with changes to module device table for new SoundWire
device type.

Signed-off-by: Sanyog Kale <sanyog.r.kale@intel.com>
Reviewed-by: Philippe Ombredanne <pombredanne@nexb.com>
Acked-By: Pierre-Louis Bossart <pierre-louis.bossart@linux.intel.com>
Reviewed-by: Takashi Iwai <tiwai@suse.de>
Acked-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Vinod Koul <vinod.koul@intel.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

3 files changed, 201 insertions, 0 deletions

diff --git a/drivers/soundwire/Kconfig b/drivers/soundwire/Kconfig
new file mode 100644
index 0000000..d7d3908
--- /dev/null
+++ b/drivers/soundwire/Kconfig
@@ -0,0 +1,22 @@
+#
+# SoundWire subsystem configuration
+#
+
+menuconfig SOUNDWIRE
+	bool "SoundWire support"
+	---help---
+	  SoundWire is a 2-Pin interface with data and clock line ratified
+	  by the MIPI Alliance. SoundWire is used for transporting data
+	  typically related to audio functions. SoundWire interface is
+	  optimized to integrate audio devices in mobile or mobile inspired
+	  systems. Say Y to enable this subsystem, N if you do not have such
+	  a device
+
+if SOUNDWIRE
+
+comment "SoundWire Devices"
+
+config SOUNDWIRE_BUS
+	tristate
+
+endif
diff --git a/drivers/soundwire/Makefile b/drivers/soundwire/Makefile
new file mode 100644
index 0000000..d1281de
--- /dev/null
+++ b/drivers/soundwire/Makefile
@@ -0,0 +1,7 @@
+#
+# Makefile for soundwire core
+#
+
+#Bus Objs
+soundwire-bus-objs := bus_type.o
+obj-$(CONFIG_SOUNDWIRE_BUS) += soundwire-bus.o
diff --git a/drivers/soundwire/bus_type.c b/drivers/soundwire/bus_type.c
new file mode 100644
index 0000000..8d8dcc6
--- /dev/null
+++ b/drivers/soundwire/bus_type.c
@@ -0,0 +1,172 @@
+// SPDX-License-Identifier: GPL-2.0
+// Copyright(c) 2015-17 Intel Corporation.
+
+#include <linux/module.h>
+#include <linux/mod_devicetable.h>
+#include <linux/pm_domain.h>
+#include <linux/soundwire/sdw.h>
+#include <linux/soundwire/sdw_type.h>
+
+/**
+ * sdw_get_device_id - find the matching SoundWire device id
+ * @slave: SoundWire Slave Device
+ * @drv: SoundWire Slave Driver
+ *
+ * The match is done by comparing the mfg_id and part_id from the
+ * struct sdw_device_id.
+ */
+static const struct sdw_device_id *
+sdw_get_device_id(struct sdw_slave *slave, struct sdw_driver *drv)
+{
+	const struct sdw_device_id *id = drv->id_table;
+
+	while (id && id->mfg_id) {
+		if (slave->id.mfg_id == id->mfg_id &&
+		    slave->id.part_id == id->part_id)
+			return id;
+		id++;
+	}
+
+	return NULL;
+}
+
+static int sdw_bus_match(struct device *dev, struct device_driver *ddrv)
+{
+	struct sdw_slave *slave = dev_to_sdw_dev(dev);
+	struct sdw_driver *drv = drv_to_sdw_driver(ddrv);
+
+	return !!sdw_get_device_id(slave, drv);
+}
+
+int sdw_slave_modalias(const struct sdw_slave *slave, char *buf, size_t size)
+{
+	/* modalias is sdw:m<mfg_id>p<part_id> */
+
+	return snprintf(buf, size, "sdw:m%04Xp%04X\n",
+			slave->id.mfg_id, slave->id.part_id);
+}
+
+static int sdw_uevent(struct device *dev, struct kobj_uevent_env *env)
+{
+	struct sdw_slave *slave = dev_to_sdw_dev(dev);
+	char modalias[32];
+
+	sdw_slave_modalias(slave, modalias, sizeof(modalias));
+
+	if (add_uevent_var(env, "MODALIAS=%s", modalias))
+		return -ENOMEM;
+
+	return 0;
+}
+
+struct bus_type sdw_bus_type = {
+	.name = "soundwire",
+	.match = sdw_bus_match,
+	.uevent = sdw_uevent,
+};
+EXPORT_SYMBOL_GPL(sdw_bus_type);
+
+static int sdw_drv_probe(struct device *dev)
+{
+	struct sdw_slave *slave = dev_to_sdw_dev(dev);
+	struct sdw_driver *drv = drv_to_sdw_driver(dev->driver);
+	const struct sdw_device_id *id;
+	int ret;
+
+	id = sdw_get_device_id(slave, drv);
+	if (!id)
+		return -ENODEV;
+
+	/*
+	 * attach to power domain but don't turn on (last arg)
+	 */
+	ret = dev_pm_domain_attach(dev, false);
+	if (ret != -EPROBE_DEFER) {
+		ret = drv->probe(slave, id);
+		if (ret) {
+			dev_err(dev, "Probe of %s failed: %d\n", drv->name, ret);
+			dev_pm_domain_detach(dev, false);
+		}
+	}
+
+	return ret;
+}
+
+static int sdw_drv_remove(struct device *dev)
+{
+	struct sdw_slave *slave = dev_to_sdw_dev(dev);
+	struct sdw_driver *drv = drv_to_sdw_driver(dev->driver);
+	int ret = 0;
+
+	if (drv->remove)
+		ret = drv->remove(slave);
+
+	dev_pm_domain_detach(dev, false);
+
+	return ret;
+}
+
+static void sdw_drv_shutdown(struct device *dev)
+{
+	struct sdw_slave *slave = dev_to_sdw_dev(dev);
+	struct sdw_driver *drv = drv_to_sdw_driver(dev->driver);
+
+	if (drv->shutdown)
+		drv->shutdown(slave);
+}
+
+/**
+ * __sdw_register_driver() - register a SoundWire Slave driver
+ * @drv: driver to register
+ * @owner: owning module/driver
+ *
+ * Return: zero on success, else a negative error code.
+ */
+int __sdw_register_driver(struct sdw_driver *drv, struct module *owner)
+{
+	drv->driver.bus = &sdw_bus_type;
+
+	if (!drv->probe) {
+		pr_err("driver %s didn't provide SDW probe routine\n",
+							drv->name);
+		return -EINVAL;
+	}
+
+	drv->driver.owner = owner;
+	drv->driver.probe = sdw_drv_probe;
+
+	if (drv->remove)
+		drv->driver.remove = sdw_drv_remove;
+
+	if (drv->shutdown)
+		drv->driver.shutdown = sdw_drv_shutdown;
+
+	return driver_register(&drv->driver);
+}
+EXPORT_SYMBOL_GPL(__sdw_register_driver);
+
+/**
+ * sdw_unregister_driver() - unregisters the SoundWire Slave driver
+ * @drv: driver to unregister
+ */
+void sdw_unregister_driver(struct sdw_driver *drv)
+{
+	driver_unregister(&drv->driver);
+}
+EXPORT_SYMBOL_GPL(sdw_unregister_driver);
+
+static int __init sdw_bus_init(void)
+{
+	return bus_register(&sdw_bus_type);
+}
+
+static void __exit sdw_bus_exit(void)
+{
+	bus_unregister(&sdw_bus_type);
+}
+
+postcore_initcall(sdw_bus_init);
+module_exit(sdw_bus_exit);
+
+MODULE_DESCRIPTION("SoundWire bus");
+MODULE_LICENSE("GPL v2");