[PATCH v2 3/4] drm/dp_mst: Add dp_mst_status debugfs node for all drivers

[Lyude Paul]

Originally I was just going to be adding dp_mst_status for nouveau until
Daniel Stone pointed out that we should probably just make this so it's
magically added for every DRM driver that's using the DRM DP MST
helpers. So, let's do that!

Signed-off-by: Lyude Paul <lyude@xxxxxxxxxx>
Cc: Maarten Lankhorst <maarten.lankhorst@xxxxxxxxxxxxxxx>
Cc: Daniel Stone <daniel@xxxxxxxxxxxxx>
---
 drivers/gpu/drm/drm_dp_mst_topology.c | 106 ++++++++++++++++++++++++++
 include/drm/drm_dp_mst_helper.h       |  14 ++++
 2 files changed, 120 insertions(+)

diff --git a/drivers/gpu/drm/drm_dp_mst_topology.c b/drivers/gpu/drm/drm_dp_mst_topology.c
index acb7633f3f70..a6a2c03af62a 100644
--- a/drivers/gpu/drm/drm_dp_mst_topology.c
+++ b/drivers/gpu/drm/drm_dp_mst_topology.c
@@ -27,6 +27,7 @@
 #include <linux/sched.h>
 #include <linux/seq_file.h>
 #include <linux/i2c.h>
+#include <linux/debugfs.h>
 #include <drm/drm_dp_mst_helper.h>
 #include <drm/drmP.h>
 
@@ -3154,6 +3155,104 @@ struct drm_dp_mst_topology_state *drm_atomic_get_mst_topology_state(struct drm_a
 }
 EXPORT_SYMBOL(drm_atomic_get_mst_topology_state);
 
+#ifdef CONFIG_DEBUG_FS
+static int drm_dp_mst_debugfs_state_show(struct seq_file *m, void *data)
+{
+	drm_dp_mst_dump_topology(m, m->private);
+	return 0;
+}
+
+static int drm_dp_mst_debugfs_state_open(struct inode *inode,
+					 struct file *file)
+{
+	struct drm_dp_mst_topology_mgr *mgr = inode->i_private;
+
+	return single_open(file, drm_dp_mst_debugfs_state_show, mgr);
+}
+
+static const struct file_operations drm_dp_mst_debugfs_state_fops = {
+	.owner = THIS_MODULE,
+	.open = drm_dp_mst_debugfs_state_open,
+	.read = seq_read,
+	.llseek = seq_lseek,
+	.release = single_release,
+};
+
+struct drm_dp_mst_debugfs_init_data {
+	struct drm_dp_mst_topology_mgr *mgr;
+	char *connector_name;
+};
+
+static void
+drm_dp_mst_debugfs_init(void *data)
+{
+	struct drm_dp_mst_debugfs_init_data *init_data = data;
+	struct drm_dp_mst_topology_mgr *mgr = init_data->mgr;
+	struct drm_minor *minor = mgr->dev->primary;
+	struct dentry *root;
+	bool put_ref = false;
+
+	/* Create the dp_mst directory for this device if it doesn't exist
+	 * already
+	 */
+	root = debugfs_lookup("dp_mst", minor->debugfs_root);
+	if (root) {
+		put_ref = true;
+	} else {
+		root = debugfs_create_dir("dp_mst", minor->debugfs_root);
+		if (!root || IS_ERR(root))
+			return;
+	}
+
+	mgr->debugfs = debugfs_create_dir(init_data->connector_name, root);
+	if (!mgr->debugfs)
+		goto out_dput;
+
+	debugfs_create_file("state", 0444, mgr->debugfs, mgr,
+			    &drm_dp_mst_debugfs_state_fops);
+
+out_dput:
+	if (put_ref)
+		dput(root);
+}
+
+static void
+drm_dp_mst_debugfs_cleanup_cb(void *data)
+{
+	struct drm_dp_mst_debugfs_init_data *init_data = data;
+
+	init_data->mgr->debugfs_init_cb = NULL;
+	kfree(init_data->connector_name);
+	kfree(init_data);
+}
+
+static void
+drm_dp_mst_debugfs_register(struct drm_dp_mst_topology_mgr *mgr,
+			    struct drm_connector *connector)
+{
+	struct drm_dp_mst_debugfs_init_data *init_data;
+
+	if (!connector)
+		return;
+
+	init_data = kmalloc(sizeof(*init_data), GFP_KERNEL);
+	if (!init_data)
+		return;
+
+	init_data->mgr = mgr;
+	init_data->connector_name = kstrdup(connector->name, GFP_KERNEL);
+	if (!init_data->connector_name) {
+		kfree(init_data);
+		return;
+	}
+
+	drm_debugfs_register_callback(mgr->dev->primary,
+				      drm_dp_mst_debugfs_init,
+				      drm_dp_mst_debugfs_cleanup_cb,
+				      init_data, &mgr->debugfs_init_cb);
+}
+#endif
+
 /**
  * drm_dp_mst_topology_mgr_init - initialise a topology manager
  * @mgr: manager struct to initialise
@@ -3214,6 +3313,9 @@ int drm_dp_mst_topology_mgr_init(struct drm_dp_mst_topology_mgr *mgr,
 	drm_atomic_private_obj_init(&mgr->base,
 				    &mst_state->base,
 				    &mst_state_funcs);
+#ifdef CONFIG_DEBUG_FS
+	drm_dp_mst_debugfs_register(mgr, connector);
+#endif
 
 	return 0;
 }
@@ -3225,6 +3327,10 @@ EXPORT_SYMBOL(drm_dp_mst_topology_mgr_init);
  */
 void drm_dp_mst_topology_mgr_destroy(struct drm_dp_mst_topology_mgr *mgr)
 {
+#ifdef CONFIG_DEBUG_FS
+	drm_debugfs_unregister_callback(mgr->dev->primary,
+					mgr->debugfs_init_cb);
+#endif
 	flush_work(&mgr->work);
 	flush_work(&mgr->destroy_connector_work);
 	mutex_lock(&mgr->payload_lock);
diff --git a/include/drm/drm_dp_mst_helper.h b/include/drm/drm_dp_mst_helper.h
index ef8ba093ae8a..c70b81cd78b1 100644
--- a/include/drm/drm_dp_mst_helper.h
+++ b/include/drm/drm_dp_mst_helper.h
@@ -25,6 +25,7 @@
 #include <linux/types.h>
 #include <drm/drm_dp_helper.h>
 #include <drm/drm_atomic.h>
+#include <drm/drm_debugfs.h>
 
 struct drm_dp_mst_branch;
 
@@ -568,6 +569,19 @@ struct drm_dp_mst_topology_mgr {
 	 * avoid locking inversion.
 	 */
 	struct work_struct destroy_connector_work;
+#ifdef CONFIG_DEBUG_FS
+	/**
+	 * @debugfs_init_cb: Pending debugfs callback for initializing the
+	 * debugfs files for this topology.
+	 */
+	struct drm_debugfs_callback *debugfs_init_cb;
+
+	/**
+	 * @debugfs_entry: dentry for dp_mst_status located in connector's
+	 * debugfs directory.
+	 */
+	struct dentry *debugfs;
+#endif
 };
 
 int drm_dp_mst_topology_mgr_init(struct drm_dp_mst_topology_mgr *mgr,
-- 
2.17.1