[PATCH v5 05/14] gtrace: Add functions to start/stop tracing on a component path

The perf driver framework needs to be able to start / stop all components
in a trace component path during its operation. Add gtrace_path_start()
and gtrace_path_stop() functions for this purpose.

Co-developed-by: Anup Patel <[email protected]>
Signed-off-by: Anup Patel <[email protected]>
Signed-off-by: Mayuresh Chitale <[email protected]>
---
 drivers/hwtracing/gtrace/gtrace-core.c | 44 ++++++++++++++++++++++++++
 include/linux/gtrace.h                 |  6 ++++
 2 files changed, 50 insertions(+)

diff --git a/drivers/hwtracing/gtrace/gtrace-core.c b/drivers/hwtracing/gtrace/gtrace-core.c
index a89d195ab5b8..6ff1b3087947 100644
--- a/drivers/hwtracing/gtrace/gtrace-core.c
+++ b/drivers/hwtracing/gtrace/gtrace-core.c
@@ -582,6 +582,50 @@ static void gtrace_release_path_nodes(struct gtrace_path *path)
 	}
 }
 
+int gtrace_path_start(struct gtrace_path *path)
+{
+	const struct gtrace_driver *gtdrv;
+	struct gtrace_component *comp;
+	struct gtrace_path_node *node;
+	int ret;
+
+	list_for_each_entry_reverse(node, &path->comp_list, head) {
+		comp = node->comp;
+		gtdrv = to_gtrace_driver(comp->dev.driver);
+		if (!gtdrv->start)
+			continue;
+
+		ret = gtdrv->start(comp);
+		if (ret)
+			return ret;
+	}
+
+	return 0;
+}
+EXPORT_SYMBOL_GPL(gtrace_path_start);
+
+int gtrace_path_stop(struct gtrace_path *path)
+{
+	const struct gtrace_driver *gtdrv;
+	struct gtrace_component *comp;
+	struct gtrace_path_node *node;
+	int ret;
+
+	list_for_each_entry(node, &path->comp_list, head) {
+		comp = node->comp;
+		gtdrv = to_gtrace_driver(comp->dev.driver);
+		if (!gtdrv->stop)
+			continue;
+
+		ret = gtdrv->stop(comp);
+		if (ret)
+			return ret;
+	}
+
+	return 0;
+}
+EXPORT_SYMBOL_GPL(gtrace_path_stop);
+
 struct gtrace_path *gtrace_create_path(struct gtrace_component *source,
 				       struct gtrace_component *sink,
 				       enum gtrace_component_mode mode)
diff --git a/include/linux/gtrace.h b/include/linux/gtrace.h
index b74d4b83b141..78e2ead3db8e 100644
--- a/include/linux/gtrace.h
+++ b/include/linux/gtrace.h
@@ -254,10 +254,14 @@ struct gtrace_path *gtrace_create_path(struct gtrace_component *source,
 				       struct gtrace_component *sink,
 				       enum gtrace_component_mode mode);
 void gtrace_destroy_path(struct gtrace_path *path);
+int gtrace_path_start(struct gtrace_path *path);
+int gtrace_path_stop(struct gtrace_path *path);
 
 /**
  * struct gtrace_driver - Representation of a trace driver.
  * @id_table:      Table to match components handled by the driver.
+ * @start:         Callback to start tracing.
+ * @stop:          Callback to stop tracing.
  * @probe:         Driver probe() function.
  * @remove:        Driver remove() function.
  * @get_trace_id:  Get/allocate a trace ID.
@@ -266,6 +270,8 @@ void gtrace_destroy_path(struct gtrace_path *path);
  */
 struct gtrace_driver {
 	const struct gtrace_component_id *id_table;
+	int			(*start)(struct gtrace_component *comp);
+	int			(*stop)(struct gtrace_component *comp);
 	int			(*probe)(struct gtrace_component *comp);
 	void			(*remove)(struct gtrace_component *comp);
 	int			(*get_trace_id)(struct gtrace_component *comp,
-- 
2.43.0


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