[RFC PATCH 6/9] soundwire: add support for sdw_slave_type

[Pierre-Louis Bossart <pierre-louis.bossart@linux.intel.com>]

Currently the bus does not have any explicit support for master
devices.  Add explicit support for sdw_slave_type, so that in
follow-up patches we can add support for the sdw_md_type (md==Master
Device), following the Grey Bus example.

Signed-off-by: Pierre-Louis Bossart <pierre-louis.bossart@linux.intel.com>
---
 drivers/soundwire/bus_type.c       | 9 ++++++++-
 drivers/soundwire/slave.c          | 7 ++++++-
 include/linux/soundwire/sdw_type.h | 6 ++++++
 3 files changed, 20 insertions(+), 2 deletions(-)

diff --git a/drivers/soundwire/bus_type.c b/drivers/soundwire/bus_type.c
index 9407ebf30012..5df095f4e12f 100644
--- a/drivers/soundwire/bus_type.c
+++ b/drivers/soundwire/bus_type.c
@@ -49,9 +49,16 @@ int sdw_slave_modalias(const struct sdw_slave *slave, char *buf, size_t size)
 
 static int sdw_uevent(struct device *dev, struct kobj_uevent_env *env)
 {
-	struct sdw_slave *slave = dev_to_sdw_dev(dev);
+	struct sdw_slave *slave;
 	char modalias[32];
 
+	if (is_sdw_slave(dev)) {
+		slave = to_sdw_slave_device(dev);
+	} else {
+		dev_warn(dev, "uevent for unknown Soundwire type\n");
+		return -EINVAL;
+	}
+
 	sdw_slave_modalias(slave, modalias, sizeof(modalias));
 
 	if (add_uevent_var(env, "MODALIAS=%s", modalias))
diff --git a/drivers/soundwire/slave.c b/drivers/soundwire/slave.c
index 40e41796a499..89854ae8414f 100644
--- a/drivers/soundwire/slave.c
+++ b/drivers/soundwire/slave.c
@@ -14,6 +14,11 @@ static void sdw_slave_release(struct device *dev)
 	kfree(slave);
 }
 
+struct device_type sdw_slave_type = {
+	.name =		"sdw_slave",
+	.release =	sdw_slave_release,
+};
+
 static int sdw_slave_add(struct sdw_bus *bus,
 			 struct sdw_slave_id *id, struct fwnode_handle *fwnode)
 {
@@ -34,9 +39,9 @@ static int sdw_slave_add(struct sdw_bus *bus,
 		     bus->link_id, id->mfg_id, id->part_id,
 		     id->class_id, id->unique_id);
 
-	slave->dev.release = sdw_slave_release;
 	slave->dev.bus = &sdw_bus_type;
 	slave->dev.of_node = of_node_get(to_of_node(fwnode));
+	slave->dev.type = &sdw_slave_type;
 	slave->bus = bus;
 	slave->status = SDW_SLAVE_UNATTACHED;
 	slave->dev_num = 0;
diff --git a/include/linux/soundwire/sdw_type.h b/include/linux/soundwire/sdw_type.h
index 7d4bc6a979bf..c681b3426478 100644
--- a/include/linux/soundwire/sdw_type.h
+++ b/include/linux/soundwire/sdw_type.h
@@ -5,6 +5,12 @@
 #define __SOUNDWIRE_TYPES_H
 
 extern struct bus_type sdw_bus_type;
+extern struct device_type sdw_slave_type;
+
+static inline int is_sdw_slave(const struct device *dev)
+{
+	return dev->type == &sdw_slave_type;
+}
 
 #define to_sdw_slave_driver(_drv) \
 	container_of(_drv, struct sdw_driver, driver)
-- 
2.20.1