[05/16] drm/vkms: Allow to configure multiple CRTCs via configfs

Commit Message

José Expósito Feb. 18, 2025, 5:07 p.m. UTC

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

Co-developed-by: Louis Chauvet <[e-mail]>
Signed-off-by: Louis Chauvet <[e-mail]>
Signed-off-by: José Expósito <[e-mail]>
---
 Documentation/gpu/vkms.rst           |  6 ++
 drivers/gpu/drm/vkms/vkms_configfs.c | 98 ++++++++++++++++++++++++++++
 2 files changed, 104 insertions(+)

Patch

diff --git a/Documentation/gpu/vkms.rst b/Documentation/gpu/vkms.rst
index d95f228de05b..da5157adfd79 100644
--- a/Documentation/gpu/vkms.rst
+++ b/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
+  ├── crtcs
   ├── enabled
   └── planes
 
@@ -88,6 +89,10 @@  Planes have 1 configurable attribute:
 
 - type: Plane type: 0 overlay, 1 primary, 2 cursor
 
+Continue by creating one or more CRTCs::
+
+  sudo mkdir /config/vkms/my-vkms/crtcs/crtc0
+
 Once you are done configuring the VKMS instance, enable it::
 
   echo "1" | sudo tee /config/vkms/my-vkms/enabled
@@ -99,6 +104,7 @@  Finally, you can remove the VKMS instance disabling it::
 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
 
 Testing With IGT
diff --git a/drivers/gpu/drm/vkms/vkms_configfs.c b/drivers/gpu/drm/vkms/vkms_configfs.c
index 093735f47858..52205a8a9cb4 100644
--- a/drivers/gpu/drm/vkms/vkms_configfs.c
+++ b/drivers/gpu/drm/vkms/vkms_configfs.c
@@ -16,6 +16,7 @@  static bool is_configfs_registered;
  * @group: Top level configuration group that represents a VKMS device.
  * Initialized when a new directory is created under "/config/vkms/"
  * @planes_group: Default subgroup of @group at "/config/vkms/planes"
+ * @crtcs_group: Default subgroup of @group at "/config/vkms/crtcs"
  * @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
@@ -24,6 +25,7 @@  static bool is_configfs_registered;
 struct vkms_configfs_device {
 	struct config_group group;
 	struct config_group planes_group;
+	struct config_group crtcs_group;
 
 	struct mutex lock;
 	struct vkms_config *config;
@@ -44,6 +46,20 @@  struct vkms_configfs_plane {
 	struct vkms_config_plane *config;
 };
 
+/**
+ * struct vkms_configfs_crtc - Configfs representation of a CRTC
+ *
+ * @group: Top level configuration group that represents a CRTC.
+ * Initialized when a new directory is created under "/config/vkms/crtcs"
+ * @dev: The vkms_configfs_device this CRTC belongs to
+ * @config: Configuration of the VKMS CRTC
+ */
+struct vkms_configfs_crtc {
+	struct config_group group;
+	struct vkms_configfs_device *dev;
+	struct vkms_config_crtc *config;
+};
+
 #define device_item_to_vkms_configfs_device(item) \
 	container_of(to_config_group((item)), struct vkms_configfs_device, \
 		     group)
@@ -54,6 +70,84 @@  struct vkms_configfs_plane {
 #define plane_item_to_vkms_configfs_plane(item) \
 	container_of(to_config_group((item)), struct vkms_configfs_plane, group)
 
+#define crtc_item_to_vkms_configfs_crtc(item) \
+	container_of(to_config_group((item)), struct vkms_configfs_crtc, group)
+
+static void crtc_release(struct config_item *item)
+{
+	struct vkms_configfs_crtc *crtc;
+	struct mutex *lock;
+
+	crtc = crtc_item_to_vkms_configfs_crtc(item);
+	lock = &crtc->dev->lock;
+
+	mutex_lock(lock);
+	vkms_config_destroy_crtc(crtc->dev->config, crtc->config);
+	kfree(crtc);
+	mutex_unlock(lock);
+}
+
+static struct configfs_item_operations crtc_item_operations = {
+	.release	= &crtc_release,
+};
+
+static const struct config_item_type crtc_item_type = {
+	.ct_item_ops	= &crtc_item_operations,
+	.ct_owner	= THIS_MODULE,
+};
+
+static struct config_group *make_crtc_group(struct config_group *group,
+					    const char *name)
+{
+	struct vkms_configfs_device *dev;
+	struct vkms_configfs_crtc *crtc;
+	int ret;
+
+	dev = child_group_to_vkms_configfs_device(group);
+
+	mutex_lock(&dev->lock);
+
+	if (dev->enabled) {
+		ret = -EINVAL;
+		goto err_unlock;
+	}
+
+	crtc = kzalloc(sizeof(*crtc), GFP_KERNEL);
+	if (!crtc) {
+		ret = -ENOMEM;
+		goto err_unlock;
+	}
+
+	crtc->dev = dev;
+
+	crtc->config = vkms_config_create_crtc(dev->config);
+	if (IS_ERR(crtc->config)) {
+		ret = PTR_ERR(crtc->config);
+		goto err_free;
+	}
+
+	config_group_init_type_name(&crtc->group, name, &crtc_item_type);
+
+	mutex_unlock(&dev->lock);
+
+	return &crtc->group;
+
+err_free:
+	kfree(crtc);
+err_unlock:
+	mutex_unlock(&dev->lock);
+	return ERR_PTR(ret);
+}
+
+static struct configfs_group_operations crtcs_group_operations = {
+	.make_group	= &make_crtc_group,
+};
+
+static const struct config_item_type crtc_group_type = {
+	.ct_group_ops	= &crtcs_group_operations,
+	.ct_owner	= THIS_MODULE,
+};
+
 static ssize_t plane_type_show(struct config_item *item, char *page)
 {
 	struct vkms_configfs_plane *plane;
@@ -289,6 +383,10 @@  static struct config_group *make_device_group(struct config_group *group,
 				    &plane_group_type);
 	configfs_add_default_group(&dev->planes_group, &dev->group);
 
+	config_group_init_type_name(&dev->crtcs_group, "crtcs",
+				    &crtc_group_type);
+	configfs_add_default_group(&dev->crtcs_group, &dev->group);
+
 	return &dev->group;
 }