drm/vkms: Allow to configure multiple connectors via configfs

Create a default subgroup at
/config/vkms/connectors to allow to create as many connectors as
required.

Tested-by: Mark Yacoub <markyacoub@google.com>
Reviewed-by: Louis Chauvet <louis.chauvet@bootlin.com>
Reviewed-by: Harry Wentland <harry.wentland@amd.com>
Reviewed-by: Luca Ceresoli <luca.ceresoli@bootlin.com>
Signed-off-by: Louis Chauvet <louis.chauvet@bootlin.com>
Co-developed-by: José Expósito <jose.exposito89@gmail.com>
Signed-off-by: José Expósito <jose.exposito89@gmail.com>
Link: https://lore.kernel.org/r/20251016175618.10051-11-jose.exposito89@gmail.com
Signed-off-by: Luca Ceresoli <luca.ceresoli@bootlin.com>

Documentation/gpu/vkms.rst

@@ -74,6 +74,7 @@ By default, the instance is disabled::
 And directories are created for each configurable item of the display pipeline::
 
   tree /config/vkms/my-vkms
+  ├── connectors
   ├── crtcs
   ├── enabled
   ├── encoders
@@ -103,6 +104,10 @@ Next, create one or more encoders::
 
   sudo mkdir /config/vkms/my-vkms/encoders/encoder0
 
+Last but not least, create one or more connectors::
+
+  sudo mkdir /config/vkms/my-vkms/connectors/connector0
+
 To finish the configuration, link the different pipeline items::
 
   sudo ln -s /config/vkms/my-vkms/crtcs/crtc0 /config/vkms/my-vkms/planes/plane0/possible_crtcs
@@ -127,6 +132,7 @@ And removing the top level directory and its subdirectories::
   sudo rmdir /config/vkms/my-vkms/planes/*
   sudo rmdir /config/vkms/my-vkms/crtcs/*
   sudo rmdir /config/vkms/my-vkms/encoders/*
+  sudo rmdir /config/vkms/my-vkms/connectors/*
   sudo rmdir /config/vkms/my-vkms
 
 Testing With IGT

drivers/gpu/drm/vkms/vkms_configfs.c

@@ -19,6 +19,7 @@ static bool is_configfs_registered;
  * @planes_group: Default subgroup of @group at "/config/vkms/planes"
  * @crtcs_group: Default subgroup of @group at "/config/vkms/crtcs"
  * @encoders_group: Default subgroup of @group at "/config/vkms/encoders"
+ * @connectors_group: Default subgroup of @group at "/config/vkms/connectors"
  * @lock: Lock used to project concurrent access to the configuration attributes
  * @config: Protected by @lock. Configuration of the VKMS device
  * @enabled: Protected by @lock. The device is created or destroyed when this
@@ -29,6 +30,7 @@ struct vkms_configfs_device {
 	struct config_group planes_group;
 	struct config_group crtcs_group;
 	struct config_group encoders_group;
+	struct config_group connectors_group;
 
 	struct mutex lock;
 	struct vkms_config *config;
@@ -81,6 +83,20 @@ struct vkms_configfs_encoder {
 	struct vkms_config_encoder *config;
 };
 
+/**
+ * struct vkms_configfs_connector - Configfs representation of a connector
+ *
+ * @group: Top level configuration group that represents a connector.
+ * Initialized when a new directory is created under "/config/vkms/connectors"
+ * @dev: The vkms_configfs_device this connector belongs to
+ * @config: Configuration of the VKMS connector
+ */
+struct vkms_configfs_connector {
+	struct config_group group;
+	struct vkms_configfs_device *dev;
+	struct vkms_config_connector *config;
+};
+
 #define device_item_to_vkms_configfs_device(item) \
 	container_of(to_config_group((item)), struct vkms_configfs_device, \
 		     group)
@@ -106,6 +122,10 @@ struct vkms_configfs_encoder {
 	container_of(to_config_group((item)), struct vkms_configfs_encoder, \
 		     possible_crtcs_group)
 
+#define connector_item_to_vkms_configfs_connector(item) \
+	container_of(to_config_group((item)), struct vkms_configfs_connector, \
+		     group)
+
 static ssize_t crtc_writeback_show(struct config_item *item, char *page)
 {
 	struct vkms_configfs_crtc *crtc;
@@ -485,6 +505,69 @@ static const struct config_item_type encoder_group_type = {
 	.ct_owner	= THIS_MODULE,
 };
 
+static void connector_release(struct config_item *item)
+{
+	struct vkms_configfs_connector *connector;
+	struct mutex *lock;
+
+	connector = connector_item_to_vkms_configfs_connector(item);
+	lock = &connector->dev->lock;
+
+	scoped_guard(mutex, lock) {
+		vkms_config_destroy_connector(connector->config);
+		kfree(connector);
+	}
+}
+
+static struct configfs_item_operations connector_item_operations = {
+	.release	= &connector_release,
+};
+
+static const struct config_item_type connector_item_type = {
+	.ct_item_ops	= &connector_item_operations,
+	.ct_owner	= THIS_MODULE,
+};
+
+static struct config_group *make_connector_group(struct config_group *group,
+						 const char *name)
+{
+	struct vkms_configfs_device *dev;
+	struct vkms_configfs_connector *connector;
+
+	dev = child_group_to_vkms_configfs_device(group);
+
+	scoped_guard(mutex, &dev->lock) {
+		if (dev->enabled)
+			return ERR_PTR(-EBUSY);
+
+		connector = kzalloc(sizeof(*connector), GFP_KERNEL);
+		if (!connector)
+			return ERR_PTR(-ENOMEM);
+
+		connector->dev = dev;
+
+		connector->config = vkms_config_create_connector(dev->config);
+		if (IS_ERR(connector->config)) {
+			kfree(connector);
+			return ERR_CAST(connector->config);
+		}
+
+		config_group_init_type_name(&connector->group, name,
+					    &connector_item_type);
+	}
+
+	return &connector->group;
+}
+
+static struct configfs_group_operations connectors_group_operations = {
+	.make_group	= &make_connector_group,
+};
+
+static const struct config_item_type connector_group_type = {
+	.ct_group_ops	= &connectors_group_operations,
+	.ct_owner	= THIS_MODULE,
+};
+
 static ssize_t device_enabled_show(struct config_item *item, char *page)
 {
 	struct vkms_configfs_device *dev;
@@ -592,6 +675,10 @@ static struct config_group *make_device_group(struct config_group *group,
 				    &encoder_group_type);
 	configfs_add_default_group(&dev->encoders_group, &dev->group);
 
+	config_group_init_type_name(&dev->connectors_group, "connectors",
+				    &connector_group_type);
+	configfs_add_default_group(&dev->connectors_group, &dev->group);
+
 	return &dev->group;
 }