drm/display: bridge-connector: hook in CEC notifier support

Allow HDMI DRM bridges to create CEC notifier. Physical address is
handled automatically by drm_atomic_helper_connector_hdmi_hotplug()
being called from .detect() path.

Signed-off-by: Dmitry Baryshkov <[e-mail]>
Reviewed-by: Maxime Ripard <[e-mail]>
Link: https://lore.kernel.org/r/[e-mail]
Signed-off-by: Dmitry Baryshkov <[e-mail]>

drivers/gpu/drm/display/drm_bridge_connector.c

···
 #include <drm/drm_print.h>
 #include <drm/drm_probe_helper.h>
 #include <drm/display/drm_hdmi_audio_helper.h>
+#include <drm/display/drm_hdmi_cec_helper.h>
 #include <drm/display/drm_hdmi_helper.h>
 #include <drm/display/drm_hdmi_state_helper.h>
 
···
 	 * &DRM_BRIDGE_OP_DP_AUDIO).
 	 */
 	struct drm_bridge *bridge_dp_audio;
+	/**
+	 * @bridge_hdmi_cec:
+	 *
+	 * The bridge in the chain that implements CEC support, if any (see
+	 * DRM_BRIDGE_OP_HDMI_CEC_NOTIFIER).
+	 */
+	struct drm_bridge *bridge_hdmi_cec;
 };
 
 #define to_drm_bridge_connector(x) \
···
 			bridge_connector->bridge_dp_audio = bridge;
 		}
 
+		if (bridge->ops & DRM_BRIDGE_OP_HDMI_CEC_NOTIFIER) {
+			if (bridge_connector->bridge_hdmi_cec)
+				return ERR_PTR(-EBUSY);
+
+			bridge_connector->bridge_hdmi_cec = bridge;
+		}
+
 		if (!drm_bridge_get_next_bridge(bridge))
 			connector_type = bridge->type;
 
···
 						    bridge->hdmi_audio_i2s_formats,
 						    bridge->hdmi_audio_spdif_playback,
 						    bridge->hdmi_audio_dai_port);
+		if (ret)
+			return ERR_PTR(ret);
+	}
+
+	if (bridge_connector->bridge_hdmi_cec &&
+	    bridge_connector->bridge_hdmi_cec->ops & DRM_BRIDGE_OP_HDMI_CEC_NOTIFIER) {
+		ret = drmm_connector_hdmi_cec_notifier_register(connector,
+								NULL,
+								bridge->hdmi_cec_dev);
 		if (ret)
 			return ERR_PTR(ret);
 	}

include/drm/drm_bridge.h

···
 	 * flag.
 	 */
 	DRM_BRIDGE_OP_DP_AUDIO = BIT(6),
+	/**
+	 * @DRM_BRIDGE_OP_HDMI_CEC_NOTIFIER: The bridge requires CEC notifier
+	 * to be present.
+	 */
+	DRM_BRIDGE_OP_HDMI_CEC_NOTIFIER = BIT(7),
 };
 
 /**
···
 	 * @DRM_BRIDGE_OP_HDMI is set.
 	 */
 	unsigned int max_bpc;
+
+	/**
+	 * @hdmi_cec_dev: device to be used as a containing device for CEC
+	 * functions.
+	 */
+	struct device *hdmi_cec_dev;
 
 	/**
 	 * @hdmi_audio_dev: device to be used as a parent for the HDMI Codec if