[PATCH v8 3/9] drm/display: Add Type-C switch helpers

[Pin-yen Lin]

Add helpers to register and unregister Type-C "switches" for bridges
capable of switching their output between two downstream devices.

The helper registers USB Type-C mode switches when the "mode-switch"
and the "data-lanes" properties are available in Device Tree.

Signed-off-by: Pin-yen Lin <treapking@xxxxxxxxxxxx>

---

Changes in v8:
- Fixed the build issue when CONFIG_TYPEC=m
- Fixed some style issues

Changes in v7:
- Extracted the common codes to a helper function
- New in v7

 drivers/gpu/drm/display/drm_dp_helper.c | 132 ++++++++++++++++++++++++
 include/drm/display/drm_dp_helper.h     |  16 +++
 2 files changed, 148 insertions(+)

diff --git a/drivers/gpu/drm/display/drm_dp_helper.c b/drivers/gpu/drm/display/drm_dp_helper.c
index 16565a0a5da6..fb9e23744c08 100644
--- a/drivers/gpu/drm/display/drm_dp_helper.c
+++ b/drivers/gpu/drm/display/drm_dp_helper.c
@@ -30,11 +30,13 @@
 #include <linux/sched.h>
 #include <linux/seq_file.h>
 #include <linux/string_helpers.h>
+#include <linux/usb/typec_mux.h>
 #include <linux/dynamic_debug.h>
 
 #include <drm/display/drm_dp_helper.h>
 #include <drm/display/drm_dp_mst_helper.h>
 #include <drm/drm_edid.h>
+#include <drm/drm_of.h>
 #include <drm/drm_print.h>
 #include <drm/drm_vblank.h>
 #include <drm/drm_panel.h>
@@ -3891,3 +3893,133 @@ int drm_panel_dp_aux_backlight(struct drm_panel *panel, struct drm_dp_aux *aux)
 EXPORT_SYMBOL(drm_panel_dp_aux_backlight);
 
 #endif
+
+#if IS_REACHABLE(CONFIG_TYPEC)
+static int drm_dp_register_mode_switch(struct device *dev, struct device_node *node,
+				       struct drm_dp_typec_switch_desc *switch_desc,
+				       void *data, void *mux_set)
+{
+	struct drm_dp_typec_port_data *port_data;
+	struct typec_mux_desc mux_desc = {};
+	char name[32];
+	u32 dp_lanes[2];
+	int ret, num_lanes, port_num = -1;
+
+	num_lanes = drm_of_get_data_lanes_count(node, 0, 2);
+	if (num_lanes <= 0) {
+		dev_err(dev, "Error on getting data lanes count: %d\n",
+			num_lanes);
+		return num_lanes;
+	}
+
+	ret = of_property_read_u32_array(node, "data-lanes", dp_lanes, num_lanes);
+	if (ret) {
+		dev_err(dev, "Failed to read the data-lanes variable: %d\n",
+			ret);
+		return ret;
+	}
+
+	port_num = dp_lanes[0] / 2;
+
+	port_data = &switch_desc->typec_ports[port_num];
+	port_data->data = data;
+	mux_desc.fwnode = &node->fwnode;
+	mux_desc.drvdata = port_data;
+	snprintf(name, sizeof(name), "%s-%u", node->name, port_num);
+	mux_desc.name = name;
+	mux_desc.set = mux_set;
+
+	port_data->typec_mux = typec_mux_register(dev, &mux_desc);
+	if (IS_ERR(port_data->typec_mux)) {
+		ret = PTR_ERR(port_data->typec_mux);
+		dev_err(dev, "Mode switch register for port %d failed: %d\n",
+			port_num, ret);
+	}
+
+	return ret;
+}
+
+/**
+ * drm_dp_register_typec_switches() - register Type-C switches
+ * @dev: Device that registers Type-C switches
+ * @port: Device node for the switch
+ * @switch_desc: A Type-C switch descriptor
+ * @data: Private data for the switches
+ * @mux_set: Callback function for typec_mux_set
+ *
+ * This function registers USB Type-C switches for DP bridges that can switch
+ * the output signal between their output pins.
+ *
+ * Currently only mode switches are implemented, and the function assumes the
+ * given @port device node has endpoints with "mode-switch" property.
+ * Register the endpoint as port 0 if the "data-lanes" property falls in 0/1,
+ * and register it as port 1 if "data-lanes" falls in 2/3.
+ */
+int drm_dp_register_typec_switches(struct device *dev, struct device_node *port,
+				   struct drm_dp_typec_switch_desc *switch_desc,
+				   void *data, void *mux_set)
+{
+	struct device_node *sw;
+	int ret;
+
+	for_each_child_of_node(port, sw) {
+		if (of_property_read_bool(sw, "mode-switch"))
+			switch_desc->num_typec_switches++;
+	}
+
+	if (!switch_desc->num_typec_switches) {
+		dev_warn(dev, "No Type-C switches node found\n");
+		return 0;
+	}
+
+	switch_desc->typec_ports = devm_kcalloc(
+		dev, switch_desc->num_typec_switches,
+		sizeof(struct drm_dp_typec_port_data), GFP_KERNEL);
+
+	if (!switch_desc->typec_ports)
+		return -ENOMEM;
+
+	/* Register switches for each connector. */
+	for_each_child_of_node(port, sw) {
+		if (!of_property_read_bool(sw, "mode-switch"))
+			continue;
+		ret = drm_dp_register_mode_switch(dev, sw, switch_desc, data, mux_set);
+		if (ret)
+			goto err_unregister_typec_switches;
+	}
+
+	return 0;
+
+err_unregister_typec_switches:
+	of_node_put(sw);
+	drm_dp_unregister_typec_switches(switch_desc);
+	dev_err(dev, "Failed to register mode switch: %d\n", ret);
+	return ret;
+}
+EXPORT_SYMBOL(drm_dp_register_typec_switches);
+
+/**
+ * drm_dp_unregister_typec_switches() - unregister Type-C switches
+ * @switch_desc: A Type-C switch descriptor
+ */
+void drm_dp_unregister_typec_switches(struct drm_dp_typec_switch_desc *switch_desc)
+{
+	int i;
+
+	for (i = 0; i < switch_desc->num_typec_switches; i++)
+		typec_mux_unregister(switch_desc->typec_ports[i].typec_mux);
+}
+EXPORT_SYMBOL(drm_dp_unregister_typec_switches);
+#else
+void drm_dp_unregister_typec_switches(struct drm_dp_typec_switch_desc *switch_desc)
+{
+}
+EXPORT_SYMBOL(drm_dp_register_typec_switches);
+int drm_dp_register_typec_switches(struct device *dev, struct device_node *port,
+				   struct drm_dp_typec_switch_desc *switch_desc,
+				   void *data, void *mux_set)
+{
+	return 0;
+}
+EXPORT_SYMBOL(drm_dp_unregister_typec_switches);
+#endif
diff --git a/include/drm/display/drm_dp_helper.h b/include/drm/display/drm_dp_helper.h
index ab55453f2d2c..fef0a9a0d8ea 100644
--- a/include/drm/display/drm_dp_helper.h
+++ b/include/drm/display/drm_dp_helper.h
@@ -763,4 +763,20 @@ bool drm_dp_downstream_rgb_to_ycbcr_conversion(const u8 dpcd[DP_RECEIVER_CAP_SIZ
 					       const u8 port_cap[4], u8 color_spc);
 int drm_dp_pcon_convert_rgb_to_ycbcr(struct drm_dp_aux *aux, u8 color_spc);
 
+struct drm_dp_typec_port_data {
+	struct typec_mux_dev *typec_mux;
+	void *data;
+	bool dp_connected;
+};
+
+struct drm_dp_typec_switch_desc {
+	int num_typec_switches;
+	struct drm_dp_typec_port_data *typec_ports;
+};
+
+void drm_dp_unregister_typec_switches(struct drm_dp_typec_switch_desc *switch_desc);
+int drm_dp_register_typec_switches(struct device *dev, struct device_node *port,
+				   struct drm_dp_typec_switch_desc *switch_desc,
+				   void *data, void *mux_set);
+
 #endif /* _DRM_DP_HELPER_H_ */
-- 
2.39.0.314.g84b9a713c41-goog