[RFC PATCH 2/5] soundwire: core: add device tree support for slave devices

[Srinivas Kandagatla <srinivas.kandagatla@xxxxxxxxxx>]

This patch adds support to parsing device tree based
SoundWire slave devices.

Signed-off-by: Srinivas Kandagatla <srinivas.kandagatla@xxxxxxxxxx>
---
 drivers/soundwire/bus.c   |  2 +-
 drivers/soundwire/bus.h   |  1 +
 drivers/soundwire/slave.c | 54 ++++++++++++++++++++++++++++++++++++++-
 3 files changed, 55 insertions(+), 2 deletions(-)

diff --git a/drivers/soundwire/bus.c b/drivers/soundwire/bus.c
index fe745830a261..20f26cf4ba74 100644
--- a/drivers/soundwire/bus.c
+++ b/drivers/soundwire/bus.c
@@ -78,7 +78,7 @@ int sdw_add_bus_master(struct sdw_bus *bus)
 	if (IS_ENABLED(CONFIG_ACPI) && ACPI_HANDLE(bus->dev))
 		ret = sdw_acpi_find_slaves(bus);
 	else
-		ret = -ENOTSUPP; /* No ACPI/DT so error out */
+		ret = sdw_of_find_slaves(bus);
 
 	if (ret) {
 		dev_err(bus->dev, "Finding slaves failed:%d\n", ret);
diff --git a/drivers/soundwire/bus.h b/drivers/soundwire/bus.h
index 3048ca153f22..ee46befedbd1 100644
--- a/drivers/soundwire/bus.h
+++ b/drivers/soundwire/bus.h
@@ -15,6 +15,7 @@ static inline int sdw_acpi_find_slaves(struct sdw_bus *bus)
 }
 #endif
 
+int sdw_of_find_slaves(struct sdw_bus *bus);
 void sdw_extract_slave_id(struct sdw_bus *bus,
 			  u64 addr, struct sdw_slave_id *id);
 
diff --git a/drivers/soundwire/slave.c b/drivers/soundwire/slave.c
index f39a5815e25d..6e7f5cfeb854 100644
--- a/drivers/soundwire/slave.c
+++ b/drivers/soundwire/slave.c
@@ -2,6 +2,7 @@
 // Copyright(c) 2015-17 Intel Corporation.
 
 #include <linux/acpi.h>
+#include <linux/of.h>
 #include <linux/soundwire/sdw.h>
 #include <linux/soundwire/sdw_type.h>
 #include "bus.h"
@@ -28,13 +29,14 @@ static int sdw_slave_add(struct sdw_bus *bus,
 	slave->dev.parent = bus->dev;
 	slave->dev.fwnode = fwnode;
 
-	/* name shall be sdw:link:mfg:part:class:unique */
+	/* name shall be sdw:link:mfg:part:class */
 	dev_set_name(&slave->dev, "sdw:%x:%x:%x:%x:%x",
 		     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->bus = bus;
 	slave->status = SDW_SLAVE_UNATTACHED;
 	slave->dev_num = 0;
@@ -112,3 +114,53 @@ int sdw_acpi_find_slaves(struct sdw_bus *bus)
 }
 
 #endif
+
+#if IS_ENABLED(CONFIG_OF)
+/*
+ * sdw_of_find_slaves() - Find Slave devices in master device tree node
+ * @bus: SDW bus instance
+ *
+ * Scans Master DT node for SDW child Slave devices and registers it.
+ */
+int sdw_of_find_slaves(struct sdw_bus *bus)
+{
+	struct device *dev = bus->dev;
+	struct device_node *node;
+
+	if (!bus->dev->of_node)
+		return 0;
+
+	for_each_child_of_node(bus->dev->of_node, node) {
+		struct sdw_slave_id id;
+		const char *compat = NULL;
+		int unique_id, ret;
+		int ver, mfg_id, part_id, class_id;
+		compat = of_get_property(node, "compatible", NULL);
+		if (!compat)
+			continue;
+
+		ret = sscanf(compat, "sdw%x,%x,%x,%x",
+			     &ver, &mfg_id, &part_id, &class_id);
+		if (ret != 4) {
+			dev_err(dev, "Manf ID & Product code not found %s\n",
+				compat);
+			continue;
+		}
+
+		ret = of_property_read_u32(node, "sdw-instance-id", &unique_id);
+		if (ret) {
+			dev_err(dev, "Instance id not found:%d\n", ret);
+			continue;
+		}
+
+		id.sdw_version = ver - 0xF;
+		id.unique_id = unique_id;
+		id.mfg_id = mfg_id;
+		id.part_id = part_id;
+		id.class_id = class_id;
+		sdw_slave_add(bus, &id, of_fwnode_handle(node));
+	}
+	return 0;
+}
+
+#endif
-- 
2.21.0