soundwire: add device tree support for adding slavestracking-qcomlt-soundwire

Signed-off-by: Srinivas Kandagatla <srinivas.kandagatla@linaro.org>

4 files changed, 107 insertions, 1 deletions

diff --git a/Documentation/devicetree/bindings/soundwire/bus.txt b/Documentation/devicetree/bindings/soundwire/bus.txt
new file mode 100644
index 000000000000..6e00030acbcf
--- /dev/null
+++ b/Documentation/devicetree/bindings/soundwire/bus.txt
@@ -0,0 +1,51 @@
+Soundwire bus
+
+SoundWire is a 2-pin multi-drop interface with data and clock line.
+It facilitates development of low cost, efficient, high performance systems.
+
+Required property for Soundwire controller node:
+
+Required properties:
+- #address-cells	- Should be 1
+- #size-cell		- Should be 0 
+Rest of the controller bindings are very much specific to vendor.
+
+Child nodes:
+Every Soundwire controller node can contain zero or more child nodes
+representing slave devices on the bus. Every Soundwire slave device is
+uniquely determined by the enumeration address containing 5 fields:
+Soundwire Version, Instance ID, Manufacturer ID, Part ID and Class ID
+for a device.
+
+Required property for SLIMbus child node if it is present:
+- reg		- Should be ('Instance ID') from Soundwire
+		  Enumeration  Address.
+		  Instance ID Is for the cases where multiple Devices of the
+		  same type or Class are attached to the bus.
+
+- compatible	-"swrVER,MFD,PID,CID". The textual representation of
+		  Soundwire Version, Manufacturer ID, Part ID, shall be
+		  in lower case hexadecimal with leading zeroes suppressed
+		  Version number '0x10' represents SoundWire 1.0
+		  Version number '0x11' represents SoundWire 1.1
+		
+
+Soundwire example for Qualcomm's soundwire controller:
+
+	soundwire@c2d0000 {
+		compatible = "qcom,soundwire-v1.5.0"
+		reg = <0x0c2d0000 0x2000>;
+		...
+		#address-cells = <1>;
+		#size-cell = <0>;
+
+		wsa8810@0{
+			compatible = "swr10,217,211,0";
+			reg = <0>;
+		};
+
+		wsa8810@1{
+			compatible = "swr10,217,211,0";
+			reg = <1>;
+		};
+	};
diff --git a/drivers/soundwire/bus.c b/drivers/soundwire/bus.c
index 1cbfedfc20ef..0673f01053eb 100644
--- a/drivers/soundwire/bus.c
+++ b/drivers/soundwire/bus.c
@@ -77,7 +77,7 @@ 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 c77de05b8100..2e683042a526 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 ac103bd0c176..724a1f23ec88 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"
@@ -112,3 +113,56 @@ 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) {
+		unsigned long long addr;
+		struct sdw_slave_id id;
+		const char *compat = NULL;
+		int reg, ret;
+		int ver, manf_id, prod_code, class;
+
+		compat = of_get_property(node, "compatible", NULL);
+		if (!compat)
+			continue;
+
+		ret = sscanf(compat, "swr%x,%x,%x,%x", &ver, &manf_id, &prod_code, &class);
+		if (ret != 4) {
+			dev_err(dev, "Manf ID & Product code not found %s\n",
+				compat);
+			continue;
+		}
+
+		ret = of_property_read_u32(node, "reg", &reg);
+		if (ret) {
+			dev_err(dev, "Device and Instance id not found:%d\n",
+				ret);
+			continue;
+		}
+
+		id.sdw_version = ver - 0xF;
+		id.unique_id = reg;
+		id.mfg_id = manf_id;
+		id.part_id = prod_code;
+		id.class_id = class;
+
+		sdw_slave_add(bus, &id, of_fwnode_handle(node));
+	}
+	return 0;
+}
+
+#endif