[PATCH v4] Add power/gpu_frequency tracepoint.

[Peiyong Lin <lpy@google.com>]

Historically there is no common trace event for GPU frequency, in
downstream Android each different hardware vendor implements their own
way to expose GPU frequency, for example as a debugfs node.  This patch
standardize it as a common trace event in upstream linux kernel to help
the ecosystem have a common implementation across hardware vendors.
Toolings in the Linux ecosystem will benefit from this especially in the
downstream Android, where this information is critical to graphics
developers.

Signed-off-by: Peiyong Lin <lpy@google.com>
---

Changelog since v3:
 - Correct copyright title.

Changelog since v2:
 - Add more comments to indicate when the event should be emitted.
 - Change state to frequency.

Changelog since v1:
 - Use %u in TP_printk

 drivers/gpu/Makefile                    |  1 +
 drivers/gpu/trace/Kconfig               |  3 +++
 drivers/gpu/trace/Makefile              |  1 +
 drivers/gpu/trace/trace_gpu_frequency.c | 13 ++++++++++
 include/trace/events/power.h            | 33 +++++++++++++++++++++++++
 5 files changed, 51 insertions(+)
 create mode 100644 drivers/gpu/trace/trace_gpu_frequency.c

diff --git a/drivers/gpu/Makefile b/drivers/gpu/Makefile
index 835c88318cec..f289a47eb031 100644
--- a/drivers/gpu/Makefile
+++ b/drivers/gpu/Makefile
@@ -6,3 +6,4 @@ obj-$(CONFIG_TEGRA_HOST1X)	+= host1x/
 obj-y			+= drm/ vga/
 obj-$(CONFIG_IMX_IPUV3_CORE)	+= ipu-v3/
 obj-$(CONFIG_TRACE_GPU_MEM)		+= trace/
+obj-$(CONFIG_TRACE_GPU_FREQUENCY)		+= trace/
diff --git a/drivers/gpu/trace/Kconfig b/drivers/gpu/trace/Kconfig
index c24e9edd022e..ac4aec8d5845 100644
--- a/drivers/gpu/trace/Kconfig
+++ b/drivers/gpu/trace/Kconfig
@@ -2,3 +2,6 @@
 
 config TRACE_GPU_MEM
 	bool
+
+config TRACE_GPU_FREQUENCY
+	bool
diff --git a/drivers/gpu/trace/Makefile b/drivers/gpu/trace/Makefile
index b70fbdc5847f..2b7ae69327d6 100644
--- a/drivers/gpu/trace/Makefile
+++ b/drivers/gpu/trace/Makefile
@@ -1,3 +1,4 @@
 # SPDX-License-Identifier: GPL-2.0
 
 obj-$(CONFIG_TRACE_GPU_MEM) += trace_gpu_mem.o
+obj-$(CONFIG_TRACE_GPU_FREQUENCY) += trace_gpu_frequency.o
diff --git a/drivers/gpu/trace/trace_gpu_frequency.c b/drivers/gpu/trace/trace_gpu_frequency.c
new file mode 100644
index 000000000000..668fabd6b77a
--- /dev/null
+++ b/drivers/gpu/trace/trace_gpu_frequency.c
@@ -0,0 +1,13 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * GPU frequency trace points
+ *
+ * Copyright (C) 2020 Google LLC
+ */
+
+#include <linux/module.h>
+
+#define CREATE_TRACE_POINTS
+#include <trace/events/power.h>
+
+EXPORT_TRACEPOINT_SYMBOL(gpu_frequency);
diff --git a/include/trace/events/power.h b/include/trace/events/power.h
index af5018aa9517..343825a76953 100644
--- a/include/trace/events/power.h
+++ b/include/trace/events/power.h
@@ -500,6 +500,39 @@ DEFINE_EVENT(dev_pm_qos_request, dev_pm_qos_remove_request,
 
 	TP_ARGS(name, type, new_value)
 );
+
+/**
+ * gpu_frequency - Reports the GPU frequency in GPU clock domains.
+ *
+ * This event should be emitted whenever there's a GPU frequency change happens,
+ * or a GPU goes from idle state to active state, or vice versa.
+ *
+ * When the GPU goes from idle state to active state, this event should report
+ * the GPU frequency of the active state. When the GPU goes from active state to
+ * idle state, this event should report a zero frequency value.
+ *
+ * @frequency:  New frequency (in KHz)
+ * @gpu_id: Id for each GPU clock domain
+ */
+TRACE_EVENT(gpu_frequency,
+
+	TP_PROTO(unsigned int frequency, unsigned int gpu_id),
+
+	TP_ARGS(frequency, gpu_id),
+
+	TP_STRUCT__entry(
+		__field(unsigned int, frequency)
+		__field(unsigned int, gpu_id)
+	),
+
+	TP_fast_assign(
+		__entry->frequency = frequency;
+		__entry->gpu_id = gpu_id;
+	),
+
+	TP_printk("frequency=%u gpu_id=%u",
+		__entry->frequency, __entry->gpu_id)
+);
 #endif /* _TRACE_POWER_H */
 
 /* This part must be outside protection */
-- 
2.29.0.rc1.297.gfa9743e501-goog