Add a function to find a connector based on a fwnode.

This will be used by the new drm_connector_oob_hotplug_event()
function which is added by the next patch in this patch-set.

Changes in v2:
- Complete rewrite to use a global connector list in drm_connector.c
  rather then using a class-dev-iter in drm_sysfs.c

Signed-off-by: Hans de Goede <hdegoede@redhat.com>
---
 drivers/gpu/drm/drm_connector.c     | 50 +++++++++++++++++++++++++++++
 drivers/gpu/drm/drm_crtc_internal.h |  1 +
 include/drm/drm_connector.h         |  8 +++++
 3 files changed, 59 insertions(+)

diff --git a/drivers/gpu/drm/drm_connector.c b/drivers/gpu/drm/drm_connector.c
index 87c68563e6c3..ef759d6add81 100644
--- a/drivers/gpu/drm/drm_connector.c
+++ b/drivers/gpu/drm/drm_connector.c
@@ -66,6 +66,14 @@
  * support can instead use e.g. drm_helper_hpd_irq_event().
  */

+/*
+ * Global connector list for drm_connector_find_by_fwnode().
+ * Note drm_connector_[un]register() first take connector->lock and then
+ * take the connector_list_lock.
+ */
+static DEFINE_MUTEX(connector_list_lock);
+static LIST_HEAD(connector_list);
+
 struct drm_conn_prop_enum_list {
        int type;
        const char *name;
@@ -267,6 +275,7 @@ int drm_connector_init(struct drm_device *dev,
                goto out_put_type_id;
        }

+       INIT_LIST_HEAD(&connector->global_connector_list_entry);
        INIT_LIST_HEAD(&connector->probed_modes);
        INIT_LIST_HEAD(&connector->modes);
        mutex_init(&connector->mutex);
@@ -540,6 +549,9 @@ int drm_connector_register(struct drm_connector *connector)
                drm_privacy_screen_register_notifier(connector->privacy_screen,
                                           &connector->privacy_screen_notifier);

+       mutex_lock(&connector_list_lock);
+       list_add_tail(&connector->global_connector_list_entry, &connector_list);
+       mutex_unlock(&connector_list_lock);
        goto unlock;

 err_debugfs:
@@ -568,6 +580,10 @@ void drm_connector_unregister(struct drm_connector *connector)
                return;
        }

+       mutex_lock(&connector_list_lock);
+       list_del_init(&connector->global_connector_list_entry);
+       mutex_unlock(&connector_list_lock);
+
        if (connector->privacy_screen)
                drm_privacy_screen_unregister_notifier(
                                        connector->privacy_screen,
@@ -2676,6 +2692,40 @@ int drm_mode_getconnector(struct drm_device *dev, void *data,
        return ret;
 }

+/**
+ * drm_connector_find_by_fwnode - Find a connector based on the associated fwnode
+ * @fwnode: fwnode for which to find the matching drm_connector
+ *
+ * This functions looks up a drm_connector based on its associated fwnode. When
+ * a connector is found a reference to the connector is returned. The caller must
+ * call drm_connector_put() to release this reference when it is done with the
+ * connector.
+ *
+ * Returns: A reference to the found connector or an ERR_PTR().
+ */
+struct drm_connector *drm_connector_find_by_fwnode(struct fwnode_handle *fwnode)
+{
+       struct drm_connector *connector, *found = ERR_PTR(-ENODEV);
+
+       if (!fwnode)
+               return ERR_PTR(-ENODEV);
+
+       mutex_lock(&connector_list_lock);
+
+       list_for_each_entry(connector, &connector_list, global_connector_list_entry) {
+               if (connector->fwnode == fwnode ||
+                   (connector->fwnode && connector->fwnode->secondary == fwnode)) {
+                       drm_connector_get(connector);
+                       found = connector;
+                       break;
+               }
+       }
+
+       mutex_unlock(&connector_list_lock);
+
+       return found;

+}
+

 /**
  * DOC: Tile group
diff --git a/drivers/gpu/drm/drm_crtc_internal.h b/drivers/gpu/drm/drm_crtc_internal.h
index 54d4cf1233e9..6e28fc00a740 100644
--- a/drivers/gpu/drm/drm_crtc_internal.h
+++ b/drivers/gpu/drm/drm_crtc_internal.h
@@ -185,6 +185,7 @@ int drm_connector_set_obj_prop(struct drm_mode_object *obj,
 int drm_connector_create_standard_properties(struct drm_device *dev);
 const char *drm_get_connector_force_name(enum drm_connector_force force);
 void drm_connector_free_work_fn(struct work_struct *work);
+struct drm_connector *drm_connector_find_by_fwnode(struct fwnode_handle *fwnode);

 /* IOCTL */
 int drm_connector_property_set_ioctl(struct drm_device *dev,
diff --git a/include/drm/drm_connector.h b/include/drm/drm_connector.h
index d20bfd7576ed..ae377354e48e 100644
--- a/include/drm/drm_connector.h
+++ b/include/drm/drm_connector.h
@@ -1267,6 +1267,14 @@ struct drm_connector {
         */
        struct list_head head;

+       /**
+        * @global_connector_list_entry:
+        *
+        * Connector entry in the global connector-list, used by
+        * drm_connector_find_by_fwnode().
+        */
+       struct list_head global_connector_list_entry;
+
        /** @base: base KMS object */
        struct drm_mode_object base;
 
--
2.31.1