soundwire: mipi-disco: add support for DP0/DPn 'lane-list' property

The SoundWire specification did not clearly require that ports could
use all Lanes. Some SoundWire/SDCA peripheral adopters added
restrictions on which lanes can be used by what port, and the DisCo
for SoundWire 2.1 specification added a 'lane-list' property to model
this hardware limitation.

When not specified, the ports can use all Lanes. Otherwise, the
'lane-list' indicates which Lanes can be used, sorted by order of
preference (most-preferred-first).

This patch only reads the properties, the use of this property will
come at a later time with multi-lane support.

Signed-off-by: Pierre-Louis Bossart <pierre-louis.bossart@linux.intel.com>

drivers/soundwire/mipi_disco.c

@@ -177,6 +177,22 @@ static int sdw_slave_read_dp0(struct sdw_slave *slave,
 	dp0->imp_def_interrupts = fwnode_property_read_bool(port,
 				"mipi-sdw-imp-def-dp0-interrupts-supported");
 
+	nval = fwnode_property_count_u32(port, "mipi-sdw-lane-list");
+	if (nval > 0) {
+		dp0->num_lanes = nval;
+		dp0->lane_list = devm_kcalloc(&slave->dev,
+					      dp0->num_lanes, sizeof(*dp0->lane_list),
+					      GFP_KERNEL);
+		if (!dp0->lane_list)
+			return -ENOMEM;
+
+		ret = fwnode_property_read_u32_array(port,
+					       "mipi-sdw-lane-list",
+					       dp0->lane_list, dp0->num_lanes);
+		if (ret < 0)
+			return ret;
+	}
+
 	return 0;
 }
 
@@ -306,6 +322,22 @@ static int sdw_slave_read_dpn(struct sdw_slave *slave,
 		fwnode_property_read_u32(node, "mipi-sdw-port-encoding-type",
 					 &dpn[i].port_encoding);
 
+		nval = fwnode_property_count_u32(node, "mipi-sdw-lane-list");
+		if (nval > 0) {
+			dpn[i].num_lanes = nval;
+			dpn[i].lane_list = devm_kcalloc(&slave->dev,
+							dpn[i].num_lanes, sizeof(*dpn[i].lane_list),
+							GFP_KERNEL);
+			if (!dpn[i].lane_list)
+				return -ENOMEM;
+
+			ret = fwnode_property_read_u32_array(node,
+						       "mipi-sdw-lane-list",
+						       dpn[i].lane_list, dpn[i].num_lanes);
+			if (ret < 0)
+				return ret;
+		}
+
 		fwnode_handle_put(node);
 
 		i++;

include/linux/soundwire/sdw.h

@@ -238,6 +238,8 @@ enum sdw_clk_stop_mode {
  * @ch_prep_timeout: Port-specific timeout value, in milliseconds
  * @imp_def_interrupts: If set, each bit corresponds to support for
  * implementation-defined interrupts
+ * @num_lanes: array size of @lane_list
+ * @lane_list: indicates which Lanes can be used by DP0
  *
  * The wordlengths are specified by Spec as max, min AND number of
  * discrete values, implementation can define based on the wordlengths they
@@ -252,6 +254,8 @@ struct sdw_dp0_prop {
 	bool simple_ch_prep_sm;
 	u32 ch_prep_timeout;
 	bool imp_def_interrupts;
+	int num_lanes;
+	u32 *lane_list;
 };
 
 /**
@@ -283,6 +287,8 @@ struct sdw_dp0_prop {
  * @block_pack_mode: Type of block port mode supported
  * @read_only_wordlength: Read Only wordlength field in DPN_BlockCtrl1 register
  * @port_encoding: Payload Channel Sample encoding schemes supported
+ * @num_lanes: array size of @lane_list
+ * @lane_list: indicates which Lanes can be used by DPn
  */
 struct sdw_dpn_prop {
 	u32 num;
@@ -306,6 +312,8 @@ struct sdw_dpn_prop {
 	bool block_pack_mode;
 	bool read_only_wordlength;
 	u32 port_encoding;
+	int num_lanes;
+	u32 *lane_list;
 };
 
 /**