1 files changed, 61 insertions, 0 deletions
diff --git a/drivers/gpu/drm/drm_of.c b/drivers/gpu/drm/drm_of.c
index 9a2cfab3a177..2c1ee601f1d8 100644
--- a/drivers/gpu/drm/drm_of.c
+++ b/drivers/gpu/drm/drm_of.c
@@ -430,3 +430,64 @@ int drm_of_lvds_get_data_mapping(const struct device_node *port)
 	return -EINVAL;
 }
 EXPORT_SYMBOL_GPL(drm_of_lvds_get_data_mapping);
+
+/**
+ * drm_of_get_data_lanes_count - Get DSI/(e)DP data lane count
+ * @endpoint: DT endpoint node of the DSI/(e)DP source or sink
+ * @min: minimum supported number of data lanes
+ * @max: maximum supported number of data lanes
+ *
+ * Count DT "data-lanes" property elements and check for validity.
+ *
+ * Return:
+ * * min..max - positive integer count of "data-lanes" elements
+ * * -ve - the "data-lanes" property is missing or invalid
+ * * -EINVAL - the "data-lanes" property is unsupported
+ */
+int drm_of_get_data_lanes_count(const struct device_node *endpoint,
+				const unsigned int min, const unsigned int max)
+{
+	int ret;
+
+	ret = of_property_count_u32_elems(endpoint, "data-lanes");
+	if (ret < 0)
+		return ret;
+
+	if (ret < min || ret > max)
+		return -EINVAL;
+
+	return ret;
+}
+EXPORT_SYMBOL_GPL(drm_of_get_data_lanes_count);
+
+/**
+ * drm_of_get_data_lanes_count_ep - Get DSI/(e)DP data lane count by endpoint
+ * @port: DT port node of the DSI/(e)DP source or sink
+ * @port_reg: identifier (value of reg property) of the parent port node
+ * @reg: identifier (value of reg property) of the endpoint node
+ * @min: minimum supported number of data lanes
+ * @max: maximum supported number of data lanes
+ *
+ * Count DT "data-lanes" property elements and check for validity.
+ * This variant uses endpoint specifier.
+ *
+ * Return:
+ * * min..max - positive integer count of "data-lanes" elements
+ * * -EINVAL - the "data-mapping" property is unsupported
+ * * -ENODEV - the "data-mapping" property is missing
+ */
+int drm_of_get_data_lanes_count_ep(const struct device_node *port,
+				   int port_reg, int reg,
+				   const unsigned int min,
+				   const unsigned int max)
+{
+	struct device_node *endpoint;
+	int ret;
+
+	endpoint = of_graph_get_endpoint_by_regs(port, port_reg, reg);
+	ret = drm_of_get_data_lanes_count(endpoint, min, max);
+	of_node_put(endpoint);
+
+	return ret;
+}
+EXPORT_SYMBOL_GPL(drm_of_get_data_lanes_count_ep);