soundwire: bus_type: add sdw_master_device support

In the existing SoundWire code, Master Devices are not explicitly
represented - only SoundWire Slave Devices are exposed (the use of
capital letters follows the SoundWire specification conventions).

With the existing code, the bus is handled without using a proper device,
and bus->dev typically points to a platform device. The right thing to
do as discussed in multiple reviews is use a device for each bus.

The sdw_master_device addition is done with minimal internal plumbing
and not exposed externally. The existing API based on
sdw_bus_master_add() and sdw_bus_master_delete() will deal with the
sdw_master_device life cycle, which minimizes changes to existing
drivers.

Note that the Intel code will be modified in follow-up patches (no
impact on any platform since the connection with ASoC is not supported
upstream so far).

Signed-off-by: Pierre-Louis Bossart <pierre-louis.bossart@linux.intel.com>
Signed-off-by: Bard Liao <yung-chuan.liao@linux.intel.com>
Acked-by: Jaroslav Kysela <perex@perex.cz>
Link: https://lore.kernel.org/r/20200518174322.31561-5-yung-chuan.liao@linux.intel.com
Signed-off-by: Vinod Koul <vkoul@kernel.org>

1 files changed, 16 insertions, 1 deletions

diff --git a/include/linux/soundwire/sdw.h b/include/linux/soundwire/sdw.h
index a32cb26f1815..7658d9698dd5 100644
--- a/include/linux/soundwire/sdw.h
+++ b/include/linux/soundwire/sdw.h
@@ -632,6 +632,19 @@ struct sdw_slave {
 
 #define dev_to_sdw_dev(_dev) container_of(_dev, struct sdw_slave, dev)
 
+/**
+ * struct sdw_master_device - SoundWire 'Master Device' representation
+ * @dev: Linux device for this Master
+ * @bus: Bus handle shortcut
+ */
+struct sdw_master_device {
+	struct device dev;
+	struct sdw_bus *bus;
+};
+
+#define dev_to_sdw_master_device(d)	\
+	container_of(d, struct sdw_master_device, dev)
+
 struct sdw_driver {
 	const char *name;
 
@@ -787,7 +800,8 @@ struct sdw_master_ops {
 
 /**
  * struct sdw_bus - SoundWire bus
- * @dev: Master linux device
+ * @dev: Shortcut to &bus->md->dev to avoid changing the entire code.
+ * @md: Master device
  * @link_id: Link id number, can be 0 to N, unique for each Master
  * @id: bus system-wide unique id
  * @slaves: list of Slaves on this bus
@@ -813,6 +827,7 @@ struct sdw_master_ops {
  */
 struct sdw_bus {
 	struct device *dev;
+	struct sdw_master_device *md;
 	unsigned int link_id;
 	int id;
 	struct list_head slaves;