soundwire: mipi_disco: read lane mapping properties from ACPI

The DisCo for SoundWire 2.0 added support for the
'mipi-sdw-lane-<n>-mapping' property.

Co-developed-by: Chao Song <[email protected]>
Signed-off-by: Chao Song <[email protected]>
Signed-off-by: Bard Liao <[email protected]>

drivers/soundwire/mipi_disco.c

@@ -366,6 +366,44 @@ static int sdw_slave_read_dpn(struct sdw_slave *slave,
 	return 0;
 }
 
+/*
+ * In MIPI DisCo spec for SoundWire, lane mapping for a slave device is done with
+ * mipi-sdw-lane-x-mapping properties, where x is 1..7, and the values for those
+ * properties are mipi-sdw-manager-lane-x or mipi-sdw-peripheral-link-y, where x
+ * is an integer between 1 to 7 if the lane is connected to a manager lane, y is a
+ * character between A to E if the lane is connected to another peripheral lane.
+ */
+int sdw_slave_read_lane_mapping(struct sdw_slave *slave)
+{
+	struct sdw_slave_prop *prop = &slave->prop;
+	struct device *dev = &slave->dev;
+	char prop_name[30];
+	const char *prop_val;
+	size_t len;
+	int ret, i;
+	u8 lane;
+
+	for (i = 0; i < SDW_MAX_LANES; i++) {
+		snprintf(prop_name, sizeof(prop_name), "mipi-sdw-lane-%d-mapping", i);
+		ret = device_property_read_string(dev, prop_name, &prop_val);
+		if (ret)
+			continue;
+
+		len = strlen(prop_val);
+		if (len < 1)
+			return -EINVAL;
+
+		/* The last character is enough to identify the connection */
+		ret = kstrtou8(&prop_val[len - 1], 10, &lane);
+		if (ret)
+			return ret;
+		if (in_range(lane, 1, SDW_MAX_LANES - 1))
+			prop->lane_maps[i] = lane;
+	}
+	return 0;
+}
+EXPORT_SYMBOL(sdw_slave_read_lane_mapping);
+
 /**
  * sdw_slave_read_prop() - Read Slave properties
  * @slave: SDW Slave
@@ -486,6 +524,6 @@ int sdw_slave_read_prop(struct sdw_slave *slave)
 	sdw_slave_read_dpn(slave, prop->sink_dpn_prop, nval,
 			   prop->sink_ports, "sink");
 
-	return 0;
+	return sdw_slave_read_lane_mapping(slave);
 }
 EXPORT_SYMBOL(sdw_slave_read_prop);

include/linux/soundwire/sdw.h

@@ -46,6 +46,8 @@ struct sdw_slave;
 #define SDW_MAX_PORTS			15
 #define SDW_VALID_PORT_RANGE(n)		((n) < SDW_MAX_PORTS && (n) >= 1)
 
+#define SDW_MAX_LANES		8
+
 enum {
 	SDW_PORT_DIRN_SINK = 0,
 	SDW_PORT_DIRN_SOURCE,
@@ -348,6 +350,7 @@ struct sdw_dpn_prop {
  * and masks are supported
  * @commit_register_supported: is PCP_Commit register supported
  * @scp_int1_mask: SCP_INT1_MASK desired settings
+ * @lane_maps: Lane mapping for the slave, only valid if lane_control_support is set
  * @clock_reg_supported: the Peripheral implements the clock base and scale
  * registers introduced with the SoundWire 1.2 specification. SDCA devices
  * do not need to set this boolean property as the registers are required.
@@ -377,6 +380,7 @@ struct sdw_slave_prop {
 	u32 sdca_interrupt_register_list;
 	u8 commit_register_supported;
 	u8 scp_int1_mask;
+	u8 lane_maps[SDW_MAX_LANES];
 	bool clock_reg_supported;
 	bool use_domain_irq;
 };
@@ -442,6 +446,7 @@ struct sdw_master_prop {
 
 int sdw_master_read_prop(struct sdw_bus *bus);
 int sdw_slave_read_prop(struct sdw_slave *slave);
+int sdw_slave_read_lane_mapping(struct sdw_slave *slave);
 
 /*
  * SDW Slave Structures and APIs