[PATCH v4 3/3] interconnect: Add basic tracepoints

[Georgi Djakov <georgi.djakov@linaro.org>]

The tracepoints can help with understanding the system behavior of a
given interconnect path when the consumer drivers change their bandwidth
demands. This might be interesting when we want to monitor the requested
interconnect bandwidth for each client driver. The paths may share the
same nodes and this will help to understand "who and when is requesting
what". All this is useful for subsystem drivers developers and may also
provide hints when optimizing the power and performance profile of the
system.

Reviewed-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
Signed-off-by: Georgi Djakov <georgi.djakov@linaro.org>
---
 drivers/interconnect/Makefile |  1 +
 drivers/interconnect/core.c   |  7 +++
 drivers/interconnect/trace.h  | 88 +++++++++++++++++++++++++++++++++++
 3 files changed, 96 insertions(+)
 create mode 100644 drivers/interconnect/trace.h

diff --git a/drivers/interconnect/Makefile b/drivers/interconnect/Makefile
index 28f2ab0824d5..725029ae7a2c 100644
--- a/drivers/interconnect/Makefile
+++ b/drivers/interconnect/Makefile
@@ -1,5 +1,6 @@
 # SPDX-License-Identifier: GPL-2.0
 
+CFLAGS_core.o				:= -I$(src)
 icc-core-objs				:= core.o
 
 obj-$(CONFIG_INTERCONNECT)		+= icc-core.o
diff --git a/drivers/interconnect/core.c b/drivers/interconnect/core.c
index c9e16bc1331e..0e4852feb395 100644
--- a/drivers/interconnect/core.c
+++ b/drivers/interconnect/core.c
@@ -21,6 +21,9 @@
 
 #include "internal.h"
 
+#define CREATE_TRACE_POINTS
+#include "trace.h"
+
 static DEFINE_IDR(icc_idr);
 static LIST_HEAD(icc_providers);
 static DEFINE_MUTEX(icc_lock);
@@ -435,6 +438,8 @@ int icc_set_bw(struct icc_path *path, u32 avg_bw, u32 peak_bw)
 
 		/* aggregate requests for this node */
 		aggregate_requests(node);
+
+		trace_icc_set_bw(path, node, i, avg_bw, peak_bw);
 	}
 
 	ret = apply_constraints(path);
@@ -453,6 +458,8 @@ int icc_set_bw(struct icc_path *path, u32 avg_bw, u32 peak_bw)
 
 	mutex_unlock(&icc_lock);
 
+	trace_icc_set_bw_end(path, ret);
+
 	return ret;
 }
 EXPORT_SYMBOL_GPL(icc_set_bw);
diff --git a/drivers/interconnect/trace.h b/drivers/interconnect/trace.h
new file mode 100644
index 000000000000..3d668ff566bf
--- /dev/null
+++ b/drivers/interconnect/trace.h
@@ -0,0 +1,88 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+/*
+ * Interconnect framework tracepoints
+ * Copyright (c) 2019, Linaro Ltd.
+ * Author: Georgi Djakov <georgi.djakov@linaro.org>
+ */
+
+#undef TRACE_SYSTEM
+#define TRACE_SYSTEM interconnect
+
+#if !defined(_TRACE_INTERCONNECT_H) || defined(TRACE_HEADER_MULTI_READ)
+#define _TRACE_INTERCONNECT_H
+
+#include <linux/interconnect.h>
+#include <linux/tracepoint.h>
+
+TRACE_EVENT(icc_set_bw,
+
+	TP_PROTO(struct icc_path *p, struct icc_node *n, int i,
+		 u32 avg_bw, u32 peak_bw),
+
+	TP_ARGS(p, n, i, avg_bw, peak_bw),
+
+	TP_STRUCT__entry(
+		__string(path_name, p->name)
+		__string(dev, dev_name(p->reqs[i].dev))
+		__string(node_name, n->name)
+		__field(u32, avg_bw)
+		__field(u32, peak_bw)
+		__field(u32, node_avg_bw)
+		__field(u32, node_peak_bw)
+	),
+
+	TP_fast_assign(
+		__assign_str(path_name, p->name);
+		__assign_str(dev, dev_name(p->reqs[i].dev));
+		__assign_str(node_name, n->name);
+		__entry->avg_bw = avg_bw;
+		__entry->peak_bw = peak_bw;
+		__entry->node_avg_bw = n->avg_bw;
+		__entry->node_peak_bw = n->peak_bw;
+	),
+
+	TP_printk("path=%s dev=%s node=%s avg_bw=%u peak_bw=%u agg_avg=%u agg_peak=%u",
+		  __get_str(path_name),
+		  __get_str(dev),
+		  __get_str(node_name),
+		  __entry->avg_bw,
+		  __entry->peak_bw,
+		  __entry->node_avg_bw,
+		  __entry->node_peak_bw)
+);
+
+TRACE_EVENT(icc_set_bw_end,
+
+	TP_PROTO(struct icc_path *p, int ret),
+
+	TP_ARGS(p, ret),
+
+	TP_STRUCT__entry(
+		__string(path_name, p->name)
+		__string(dev, dev_name(p->reqs[0].dev))
+		__field(int, ret)
+	),
+
+	TP_fast_assign(
+		__assign_str(path_name, p->name);
+		__assign_str(dev, dev_name(p->reqs[0].dev));
+		__entry->ret = ret;
+	),
+
+	TP_printk("path=%s dev=%s ret=%d",
+		  __get_str(path_name),
+		  __get_str(dev),
+		  __entry->ret)
+);
+
+#endif /* _TRACE_INTERCONNECT_H */
+
+/* This part must be outside protection */
+
+#undef TRACE_INCLUDE_PATH
+#define TRACE_INCLUDE_PATH .
+
+#undef TRACE_INCLUDE_FILE
+#define TRACE_INCLUDE_FILE trace
+
+#include <trace/define_trace.h>