drm/encoder: register per-encoder debugfs dir

Each of connectors and CRTCs used by the DRM device provides debugfs
directory, which is used by several standard debugfs files and can
further be extended by the driver. Add such generic debugfs directories
for encoder.
Reviewed-by: Neil Armstrong <neil.armstrong@linaro.org>
Acked-by: Maxime Ripard <mripard@kernel.org>
Signed-off-by: Dmitry Baryshkov <dmitry.baryshkov@linaro.org>
Link: https://patchwork.freedesktop.org/patch/msgid/20231203115315.1306124-2-dmitry.baryshkov@linaro.org

drivers/gpu/drm/drm_debugfs.c

@@ -589,4 +589,29 @@ void drm_debugfs_crtc_remove(struct drm_crtc *crtc)
 	crtc->debugfs_entry = NULL;
 }
 
+void drm_debugfs_encoder_add(struct drm_encoder *encoder)
+{
+	struct drm_minor *minor = encoder->dev->primary;
+	struct dentry *root;
+	char *name;
+
+	name = kasprintf(GFP_KERNEL, "encoder-%d", encoder->index);
+	if (!name)
+		return;
+
+	root = debugfs_create_dir(name, minor->debugfs_root);
+	kfree(name);
+
+	encoder->debugfs_entry = root;
+
+	if (encoder->funcs->debugfs_init)
+		encoder->funcs->debugfs_init(encoder, root);
+}
+
+void drm_debugfs_encoder_remove(struct drm_encoder *encoder)
+{
+	debugfs_remove_recursive(encoder->debugfs_entry);
+	encoder->debugfs_entry = NULL;
+}
+
 #endif /* CONFIG_DEBUG_FS */

drivers/gpu/drm/drm_encoder.c

@@ -30,6 +30,7 @@
 #include <drm/drm_print.h>
 
 #include "drm_crtc_internal.h"
+#include "drm_internal.h"
 
 /**
  * DOC: overview
@@ -74,6 +75,8 @@ int drm_encoder_register_all(struct drm_device *dev)
 	int ret = 0;
 
 	drm_for_each_encoder(encoder, dev) {
+		drm_debugfs_encoder_add(encoder);
+
 		if (encoder->funcs && encoder->funcs->late_register)
 			ret = encoder->funcs->late_register(encoder);
 		if (ret)
@@ -90,6 +93,7 @@ void drm_encoder_unregister_all(struct drm_device *dev)
 	drm_for_each_encoder(encoder, dev) {
 		if (encoder->funcs && encoder->funcs->early_unregister)
 			encoder->funcs->early_unregister(encoder);
+		drm_debugfs_encoder_remove(encoder);
 	}
 }
 

drivers/gpu/drm/drm_internal.h

@@ -194,6 +194,8 @@ void drm_debugfs_connector_remove(struct drm_connector *connector);
 void drm_debugfs_crtc_add(struct drm_crtc *crtc);
 void drm_debugfs_crtc_remove(struct drm_crtc *crtc);
 void drm_debugfs_crtc_crc_add(struct drm_crtc *crtc);
+void drm_debugfs_encoder_add(struct drm_encoder *encoder);
+void drm_debugfs_encoder_remove(struct drm_encoder *encoder);
 #else
 static inline void drm_debugfs_dev_fini(struct drm_device *dev)
 {
@@ -231,6 +233,14 @@ static inline void drm_debugfs_crtc_crc_add(struct drm_crtc *crtc)
 {
 }
 
+static inline void drm_debugfs_encoder_add(struct drm_encoder *encoder)
+{
+}
+
+static inline void drm_debugfs_encoder_remove(struct drm_encoder *encoder)
+{
+}
+
 #endif
 
 drm_ioctl_t drm_version;

include/drm/drm_encoder.h

@@ -60,7 +60,7 @@ struct drm_encoder_funcs {
 	 * @late_register:
 	 *
 	 * This optional hook can be used to register additional userspace
-	 * interfaces attached to the encoder like debugfs interfaces.
+	 * interfaces attached to the encoder.
 	 * It is called late in the driver load sequence from drm_dev_register().
 	 * Everything added from this callback should be unregistered in
 	 * the early_unregister callback.
@@ -81,6 +81,13 @@ struct drm_encoder_funcs {
 	 * before data structures are torndown.
 	 */
 	void (*early_unregister)(struct drm_encoder *encoder);
+
+	/**
+	 * @debugfs_init:
+	 *
+	 * Allows encoders to create encoder-specific debugfs files.
+	 */
+	void (*debugfs_init)(struct drm_encoder *encoder, struct dentry *root);
 };
 
 /**
@@ -184,6 +191,13 @@ struct drm_encoder {
 
 	const struct drm_encoder_funcs *funcs;
 	const struct drm_encoder_helper_funcs *helper_private;
+
+	/**
+	 * @debugfs_entry:
+	 *
+	 * Debugfs directory for this CRTC.
+	 */
+	struct dentry *debugfs_entry;
 };
 
 #define obj_to_encoder(x) container_of(x, struct drm_encoder, base)