drm/connector: Add helper to get a connector type name

drm_connector.c contains a map of connector types (DRM_MODE_CONNECTOR_*)
to name strings, but doesn't expose it. This leads to drivers having to
store a similar map.

Add a new drm_get_connector_type_name() helper function that return a
name string for a connector type.
Signed-off-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Reviewed-by: Boris Brezillon <boris.brezillon@collabora.com>
Reviewed-by: Sam Ravnborg <sam@ravnborg.org>
Tested-by: Sebastian Reichel <sebastian.reichel@collabora.com>
Reviewed-by: Sebastian Reichel <sebastian.reichel@collabora.com>
Signed-off-by: Tomi Valkeinen <tomi.valkeinen@ti.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20200226112514.12455-3-laurent.pinchart@ideasonboard.com

drivers/gpu/drm/drm_connector.c

@@ -111,6 +111,21 @@ void drm_connector_ida_destroy(void)
 		ida_destroy(&drm_connector_enum_list[i].ida);
 }
 
+/**
+ * drm_get_connector_type_name - return a string for connector type
+ * @type: The connector type (DRM_MODE_CONNECTOR_*)
+ *
+ * Returns: the name of the connector type, or NULL if the type is not valid.
+ */
+const char *drm_get_connector_type_name(unsigned int type)
+{
+	if (type < ARRAY_SIZE(drm_connector_enum_list))
+		return drm_connector_enum_list[type].name;
+
+	return NULL;
+}
+EXPORT_SYMBOL(drm_get_connector_type_name);
+
 /**
  * drm_connector_get_cmdline_mode - reads the user's cmdline mode
  * @connector: connector to quwery

include/drm/drm_connector.h

@@ -1518,6 +1518,7 @@ drm_connector_is_unregistered(struct drm_connector *connector)
 		DRM_CONNECTOR_UNREGISTERED;
 }
 
+const char *drm_get_connector_type_name(unsigned int connector_type);
 const char *drm_get_connector_status_name(enum drm_connector_status status);
 const char *drm_get_subpixel_order_name(enum subpixel_order order);
 const char *drm_get_dpms_name(int val);