[RFC PATCH 15/17] drm/vkms: Allow to configure multiple planes via configfs

["José Expósito" <jose.exposito89@gmail.com>]

Create a default subgroup at /config/vkms/planes to allow to create as
many overlay planes as required. When the plane is created the
possible_crtcs subgroup is created allowing to link planes and CRTCs.

Signed-off-by: José Expósito <jose.exposito89@gmail.com>
---
 Documentation/gpu/vkms.rst           |  13 ++-
 drivers/gpu/drm/vkms/vkms_config.h   |   3 +
 drivers/gpu/drm/vkms/vkms_configfs.c | 121 +++++++++++++++++++++++++++
 3 files changed, 136 insertions(+), 1 deletion(-)

diff --git a/Documentation/gpu/vkms.rst b/Documentation/gpu/vkms.rst
index b6ceb8c48310..ee71d1a569dd 100644
--- a/Documentation/gpu/vkms.rst
+++ b/Documentation/gpu/vkms.rst
@@ -78,7 +78,8 @@ And directories are created for each configurable item of the display pipeline::
     ├── connectors
     ├── crtcs
     ├── enabled
-    └── encoders
+    ├── encoders
+    └── planes
 
 To add items to the display pipeline, create one or more directories under the
 available paths.
@@ -111,6 +112,14 @@ linked to encoders by creating a symbolic link under ``possible_encoders``::
 
   sudo ln -s /config/vkms/my-vkms/encoders/encoder0 /config/vkms/my-vkms/connectors/connector0/possible_encoders
 
+Finally, create zero or more overlay planes::
+
+  sudo mkdir /config/vkms/my-vkms/planes/plane0
+
+And link them with their ``possible_crtcs``::
+
+  sudo ln -s /config/vkms/my-vkms/crtcs/crtc0 /config/vkms/my-vkms/planes/plane0/possible_crtcs
+
 Once you are done configuring the VKMS instance, enable it::
 
   echo "1" | sudo tee /config/vkms/my-vkms/enabled
@@ -128,6 +137,8 @@ Or removing the top level directory and its subdirectories::
   sudo rmdir /config/vkms/my-vkms/connectors/*
   sudo rm /config/vkms/my-vkms/encoders/*/possible_crtcs/*
   sudo rmdir /config/vkms/my-vkms/encoders/*
+  sudo rm /config/vkms/my-vkms/planes/*/possible_crtcs/*
+  sudo rmdir /config/vkms/my-vkms/planes/*
   sudo rmdir /config/vkms/my-vkms/crtcs/*
   sudo rmdir /config/vkms/my-vkms
 
diff --git a/drivers/gpu/drm/vkms/vkms_config.h b/drivers/gpu/drm/vkms/vkms_config.h
index cf45e3f6ae92..2ec08bb58ec4 100644
--- a/drivers/gpu/drm/vkms/vkms_config.h
+++ b/drivers/gpu/drm/vkms/vkms_config.h
@@ -14,6 +14,9 @@ struct vkms_device;
 struct vkms_config_plane {
 	struct list_head list;
 	uint32_t possible_crtcs;
+	/* only used if created from configfs */
+	struct config_group plane_group;
+	struct config_group possible_crtcs_group;
 };
 
 struct vkms_config_crtc {
diff --git a/drivers/gpu/drm/vkms/vkms_configfs.c b/drivers/gpu/drm/vkms/vkms_configfs.c
index d2369f53e2d8..0b5ac0767da0 100644
--- a/drivers/gpu/drm/vkms/vkms_configfs.c
+++ b/drivers/gpu/drm/vkms/vkms_configfs.c
@@ -23,6 +23,8 @@ static bool is_configfs_registered;
  * "/config/vkms/encoders". Each of its items represent a encoder
  * @connectors_group: Default subgroup of @device_group at
  * "/config/vkms/connectors". Each of its items represent a connector
+ * @planes_group: Default subgroup of @device_group at "/config/vkms/planes".
+ * Each of its items represent an overlay plane
  * @lock: Lock used to project concurrent access to the configuration attributes
  * @enabled: Protected by @lock. The device is created or destroyed when this
  * option changes
@@ -33,6 +35,7 @@ struct vkms_configfs {
 	struct config_group crtcs_group;
 	struct config_group encoders_group;
 	struct config_group connectors_group;
+	struct config_group planes_group;
 
 	/* protected by @lock */
 	struct mutex lock;
@@ -72,6 +75,15 @@ struct vkms_configfs {
 #define connector_possible_encoders_item_to_vkms_config_connector(item) \
 	container_of(to_config_group(item), struct vkms_config_connector, possible_encoders_group)
 
+#define planes_group_to_vkms_configfs(group) \
+	container_of(group, struct vkms_configfs, planes_group)
+
+#define planes_item_to_vkms_config_plane(item) \
+	container_of(to_config_group(item), struct vkms_config_plane, plane_group)
+
+#define plane_possible_crtcs_item_to_vkms_config_plane(item) \
+	container_of(to_config_group(item), struct vkms_config_plane, possible_crtcs_group)
+
 static ssize_t crtc_cursor_show(struct config_item *item, char *page)
 {
 	struct vkms_config_crtc *crtc_cfg = crtcs_item_to_vkms_config_crtc(item);
@@ -450,6 +462,110 @@ static struct config_item_type connectors_group_type = {
 	.ct_owner = THIS_MODULE,
 };
 
+static int plane_possible_crtcs_allow_link(struct config_item *src,
+					   struct config_item *target)
+{
+	struct vkms_config_plane *plane_cfg;
+	struct vkms_config_crtc *crtc_cfg;
+
+	if (target->ci_type != &crtc_group_type)
+		return -EINVAL;
+
+	plane_cfg = plane_possible_crtcs_item_to_vkms_config_plane(src);
+	crtc_cfg = crtcs_item_to_vkms_config_crtc(target);
+
+	if (plane_cfg->possible_crtcs & BIT(crtc_cfg->index))
+		return -EINVAL;
+
+	plane_cfg->possible_crtcs |= BIT(crtc_cfg->index);
+
+	return 0;
+}
+
+static void plane_possible_crtcs_drop_link(struct config_item *src,
+					   struct config_item *target)
+{
+	struct vkms_config_plane *plane_cfg;
+	struct vkms_config_crtc *crtc_cfg;
+
+	plane_cfg = plane_possible_crtcs_item_to_vkms_config_plane(src);
+	crtc_cfg = crtcs_item_to_vkms_config_crtc(target);
+
+	plane_cfg->possible_crtcs &= ~BIT(crtc_cfg->index);
+}
+
+static struct configfs_item_operations plane_possible_crtcs_item_ops = {
+	.allow_link = &plane_possible_crtcs_allow_link,
+	.drop_link = &plane_possible_crtcs_drop_link,
+};
+
+static struct config_item_type plane_possible_crtcs_group_type = {
+	.ct_item_ops = &plane_possible_crtcs_item_ops,
+	.ct_owner = THIS_MODULE,
+};
+
+static const struct config_item_type plane_group_type = {
+	.ct_owner = THIS_MODULE,
+};
+
+static struct config_group *make_planes_group(struct config_group *group,
+					      const char *name)
+{
+	struct vkms_configfs *configfs = planes_group_to_vkms_configfs(group);
+	struct vkms_config_plane *plane_cfg;
+	int ret;
+
+	mutex_lock(&configfs->lock);
+
+	if (configfs->enabled) {
+		ret = -EINVAL;
+		goto err_unlock;
+	}
+
+	plane_cfg = vkms_config_add_overlay_plane(configfs->vkms_config, 0);
+	if (IS_ERR(plane_cfg)) {
+		ret = PTR_ERR(plane_cfg);
+		goto err_unlock;
+	}
+
+	config_group_init_type_name(&plane_cfg->plane_group, name,
+				    &plane_group_type);
+
+	config_group_init_type_name(&plane_cfg->possible_crtcs_group,
+				    "possible_crtcs",
+				    &plane_possible_crtcs_group_type);
+	configfs_add_default_group(&plane_cfg->possible_crtcs_group,
+				   &plane_cfg->plane_group);
+
+	mutex_unlock(&configfs->lock);
+
+	return &plane_cfg->plane_group;
+
+err_unlock:
+	mutex_unlock(&configfs->lock);
+	return ERR_PTR(ret);
+}
+
+static void drop_planes_group(struct config_group *group,
+			      struct config_item *item)
+{
+	struct vkms_configfs *configfs = planes_group_to_vkms_configfs(group);
+	struct vkms_config_plane *plane_cfg =
+		planes_item_to_vkms_config_plane(item);
+
+	vkms_config_destroy_overlay_plane(configfs->vkms_config, plane_cfg);
+}
+
+static struct configfs_group_operations planes_group_ops = {
+	.make_group = &make_planes_group,
+	.drop_item = &drop_planes_group,
+};
+
+static struct config_item_type planes_group_type = {
+	.ct_group_ops = &planes_group_ops,
+	.ct_owner = THIS_MODULE,
+};
+
 static ssize_t device_enabled_show(struct config_item *item, char *page)
 {
 	struct vkms_configfs *configfs = config_item_to_vkms_configfs(item);
@@ -538,6 +654,11 @@ static struct config_group *make_device_group(struct config_group *group,
 	configfs_add_default_group(&configfs->connectors_group,
 				   &configfs->device_group);
 
+	config_group_init_type_name(&configfs->planes_group, "planes",
+				    &planes_group_type);
+	configfs_add_default_group(&configfs->planes_group,
+				   &configfs->device_group);
+
 	return &configfs->device_group;
 }
 
-- 
2.46.0