drm/display: bridge-connector: handle CEC adapters

Implement necessary glue code to let DRM bridge drivers to implement CEC
adapters support.

Signed-off-by: Dmitry Baryshkov <dmitry.baryshkov@linaro.org>
Reviewed-by: Maxime Ripard <mripard@kernel.org>
Link: https://lore.kernel.org/r/20250517-drm-hdmi-connector-cec-v6-9-35651db6f19b@oss.qualcomm.com
Signed-off-by: Dmitry Baryshkov <dmitry.baryshkov@oss.qualcomm.com>

drivers/gpu/drm/display/Kconfig

@@ -17,6 +17,7 @@ if DRM_DISPLAY_HELPER
 config DRM_BRIDGE_CONNECTOR
 	bool
 	select DRM_DISPLAY_HDMI_AUDIO_HELPER
+	select DRM_DISPLAY_HDMI_CEC_HELPER
 	select DRM_DISPLAY_HDMI_STATE_HELPER
 	help
 	  DRM connector implementation terminating DRM bridge chains.

drivers/gpu/drm/display/drm_bridge_connector.c

@@ -554,6 +554,65 @@ static const struct drm_connector_hdmi_audio_funcs drm_bridge_connector_hdmi_aud
 	.mute_stream = drm_bridge_connector_audio_mute_stream,
 };
 
+static int drm_bridge_connector_hdmi_cec_enable(struct drm_connector *connector, bool enable)
+{
+	struct drm_bridge_connector *bridge_connector =
+		to_drm_bridge_connector(connector);
+	struct drm_bridge *bridge;
+
+	bridge = bridge_connector->bridge_hdmi_cec;
+
+	return bridge->funcs->hdmi_cec_enable(bridge, enable);
+}
+
+static int drm_bridge_connector_hdmi_cec_log_addr(struct drm_connector *connector, u8 logical_addr)
+{
+	struct drm_bridge_connector *bridge_connector =
+		to_drm_bridge_connector(connector);
+	struct drm_bridge *bridge;
+
+	bridge = bridge_connector->bridge_hdmi_cec;
+
+	return bridge->funcs->hdmi_cec_log_addr(bridge, logical_addr);
+}
+
+static int drm_bridge_connector_hdmi_cec_transmit(struct drm_connector *connector,
+						  u8 attempts,
+						  u32 signal_free_time,
+						  struct cec_msg *msg)
+{
+	struct drm_bridge_connector *bridge_connector =
+		to_drm_bridge_connector(connector);
+	struct drm_bridge *bridge;
+
+	bridge = bridge_connector->bridge_hdmi_cec;
+
+	return bridge->funcs->hdmi_cec_transmit(bridge, attempts,
+						signal_free_time,
+						msg);
+}
+
+static int drm_bridge_connector_hdmi_cec_init(struct drm_connector *connector)
+{
+	struct drm_bridge_connector *bridge_connector =
+		to_drm_bridge_connector(connector);
+	struct drm_bridge *bridge;
+
+	bridge = bridge_connector->bridge_hdmi_cec;
+
+	if (!bridge->funcs->hdmi_cec_init)
+		return 0;
+
+	return bridge->funcs->hdmi_cec_init(connector, bridge);
+}
+
+static const struct drm_connector_hdmi_cec_funcs drm_bridge_connector_hdmi_cec_funcs = {
+	.init = drm_bridge_connector_hdmi_cec_init,
+	.enable = drm_bridge_connector_hdmi_cec_enable,
+	.log_addr = drm_bridge_connector_hdmi_cec_log_addr,
+	.transmit = drm_bridge_connector_hdmi_cec_transmit,
+};
+
 /* -----------------------------------------------------------------------------
  * Bridge Connector Initialisation
  */
@@ -677,6 +736,18 @@ struct drm_connector *drm_bridge_connector_init(struct drm_device *drm,
 			bridge_connector->bridge_hdmi_cec = bridge;
 		}
 
+		if (bridge->ops & DRM_BRIDGE_OP_HDMI_CEC_ADAPTER) {
+			if (bridge_connector->bridge_hdmi_cec)
+				return ERR_PTR(-EBUSY);
+
+			bridge_connector->bridge_hdmi_cec = bridge;
+
+			if (!bridge->funcs->hdmi_cec_enable ||
+			    !bridge->funcs->hdmi_cec_log_addr ||
+			    !bridge->funcs->hdmi_cec_transmit)
+				return ERR_PTR(-EINVAL);
+		}
+
 		if (!drm_bridge_get_next_bridge(bridge))
 			connector_type = bridge->type;
 
@@ -748,6 +819,17 @@ struct drm_connector *drm_bridge_connector_init(struct drm_device *drm,
 			return ERR_PTR(ret);
 	}
 
+	if (bridge_connector->bridge_hdmi_cec &&
+	    bridge_connector->bridge_hdmi_cec->ops & DRM_BRIDGE_OP_HDMI_CEC_ADAPTER) {
+		ret = drmm_connector_hdmi_cec_register(connector,
+						       &drm_bridge_connector_hdmi_cec_funcs,
+						       bridge->hdmi_cec_adapter_name,
+						       bridge->hdmi_cec_available_las,
+						       bridge->hdmi_cec_dev);
+		if (ret)
+			return ERR_PTR(ret);
+	}
+
 	drm_connector_helper_add(connector, &drm_bridge_connector_helper_funcs);
 
 	if (bridge_connector->bridge_hpd)

include/drm/drm_bridge.h

@@ -32,6 +32,7 @@
 #include <drm/drm_mode_object.h>
 #include <drm/drm_modes.h>
 
+struct cec_msg;
 struct device_node;
 
 struct drm_bridge;
@@ -737,6 +738,16 @@ struct drm_bridge_funcs {
 				      struct drm_bridge *bridge,
 				      bool enable, int direction);
 
+	int (*hdmi_cec_init)(struct drm_connector *connector,
+			     struct drm_bridge *bridge);
+
+	int (*hdmi_cec_enable)(struct drm_bridge *bridge, bool enable);
+
+	int (*hdmi_cec_log_addr)(struct drm_bridge *bridge, u8 logical_addr);
+
+	int (*hdmi_cec_transmit)(struct drm_bridge *bridge, u8 attempts,
+				 u32 signal_free_time, struct cec_msg *msg);
+
 	/**
 	 * @dp_audio_startup:
 	 *
@@ -912,6 +923,11 @@ enum drm_bridge_ops {
 	 * to be present.
 	 */
 	DRM_BRIDGE_OP_HDMI_CEC_NOTIFIER = BIT(7),
+	/**
+	 * @DRM_BRIDGE_OP_HDMI_CEC_ADAPTER: The bridge requires CEC notifier
+	 * to be present.
+	 */
+	DRM_BRIDGE_OP_HDMI_CEC_ADAPTER = BIT(8),
 };
 
 /**
@@ -1048,6 +1064,16 @@ struct drm_bridge {
 	 */
 	int hdmi_audio_dai_port;
 
+	/**
+	 * @hdmi_cec_adapter_name: the name of the adapter to register
+	 */
+	const char *hdmi_cec_adapter_name;
+
+	/**
+	 * @hdmi_cec_available_las: number of logical addresses, CEC_MAX_LOG_ADDRS if unset
+	 */
+	u8 hdmi_cec_available_las;
+
 	/** private: */
 	/**
 	 * @hpd_mutex: Protects the @hpd_cb and @hpd_data fields.