[PATCH v5 07/14] gtrace: Add function to copy into perf AUX buffer

From: Anup Patel <[email protected]>

The RISC-V trace ramsink will need a mechanism to copy trace data
into the perf AUX buffer. Add gtrace_path_copyto_auxbuf() function
and corresponding trace driver callback copyto_auxbuf() for this
purpose.

Co-developed-by: Mayuresh Chitale <[email protected]>
Signed-off-by: Mayuresh Chitale <[email protected]>
Signed-off-by: Anup Patel <[email protected]>
---
 drivers/hwtracing/gtrace/gtrace-core.c | 22 ++++++++++++++++++++++
 include/linux/gtrace.h                 | 24 ++++++++++++++++++++++++
 2 files changed, 46 insertions(+)

diff --git a/drivers/hwtracing/gtrace/gtrace-core.c b/drivers/hwtracing/gtrace/gtrace-core.c
index 6ff1b3087947..53a3679ba69f 100644
--- a/drivers/hwtracing/gtrace/gtrace-core.c
+++ b/drivers/hwtracing/gtrace/gtrace-core.c
@@ -626,6 +626,28 @@ int gtrace_path_stop(struct gtrace_path *path)
 }
 EXPORT_SYMBOL_GPL(gtrace_path_stop);
 
+int gtrace_path_copyto_auxbuf(struct gtrace_path *path,
+			      struct gtrace_perf_auxbuf *buf,
+			      size_t *bytes_copied, u64 *format)
+{
+	const struct gtrace_driver *gtdrv;
+	struct gtrace_component *comp;
+	struct gtrace_path_node *node;
+
+	list_for_each_entry(node, &path->comp_list, head) {
+		comp = node->comp;
+		gtdrv = to_gtrace_driver(comp->dev.driver);
+		if (!gtdrv->copyto_auxbuf)
+			continue;
+
+		*bytes_copied = gtdrv->copyto_auxbuf(comp, buf, format);
+		return 0;
+	}
+
+	return -EOPNOTSUPP;
+}
+EXPORT_SYMBOL_GPL(gtrace_path_copyto_auxbuf);
+
 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 78e2ead3db8e..bc82814e2738 100644
--- a/include/linux/gtrace.h
+++ b/include/linux/gtrace.h
@@ -257,9 +257,30 @@ 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_perf_auxbuf - Representation of the perf AUX buffer.
+ * @length:   Size of the AUX buffer.
+ * @nr_pages: Number of pages of the AUX buffer.
+ * @base:     Start address of AUX buffer.
+ * @pos:      Position in the AUX buffer to commit traced data.
+ */
+struct gtrace_perf_auxbuf {
+	size_t length;
+	int nr_pages;
+	void *base;
+	long pos;
+};
+
+int gtrace_path_copyto_auxbuf(struct gtrace_path *path,
+			      struct gtrace_perf_auxbuf *buf,
+			      size_t *bytes_copied, u64 *format);
+
 /**
  * struct gtrace_driver - Representation of a trace driver.
  * @id_table:      Table to match components handled by the driver.
+ * @copyto_auxbuf: Callback to copy data into perf AUX buffer. The driver
+ *                 reports the PMU specific trace format of the copied data
+ *                 via @format (see PERF_AUX_FLAG_PMU_FORMAT_TYPE_MASK).
  * @start:         Callback to start tracing.
  * @stop:          Callback to stop tracing.
  * @probe:         Driver probe() function.
@@ -270,6 +291,9 @@ int gtrace_path_stop(struct gtrace_path *path);
  */
 struct gtrace_driver {
 	const struct gtrace_component_id *id_table;
+	size_t			(*copyto_auxbuf)(struct gtrace_component *comp,
+						 struct gtrace_perf_auxbuf *buf,
+						 u64 *format);
 	int			(*start)(struct gtrace_component *comp);
 	int			(*stop)(struct gtrace_component *comp);
 	int			(*probe)(struct gtrace_component *comp);
-- 
2.43.0


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