cpufreq: amd-pstate: Add trace for AMD P-State module

Add trace event to monitor the performance value changes which is
controlled by cpu governors.

Signed-off-by: Huang Rui <[e-mail]>
Signed-off-by: Rafael J. Wysocki <[e-mail]>

drivers/cpufreq/Makefile

···
 obj-$(CONFIG_CPUFREQ_DT)		+= cpufreq-dt.o
 obj-$(CONFIG_CPUFREQ_DT_PLATDEV)	+= cpufreq-dt-platdev.o
 
+# Traces
+CFLAGS_amd-pstate-trace.o               := -I$(src)
+amd_pstate-y				:= amd-pstate.o amd-pstate-trace.o
+
 ##################################################################################
 # x86 drivers.
 # Link order matters. K8 is preferred to ACPI because of firmware bugs in early
···
 # speedstep-* is preferred over p4-clockmod.
 
 obj-$(CONFIG_X86_ACPI_CPUFREQ)		+= acpi-cpufreq.o
-obj-$(CONFIG_X86_AMD_PSTATE)		+= amd-pstate.o
+obj-$(CONFIG_X86_AMD_PSTATE)		+= amd_pstate.o
 obj-$(CONFIG_X86_POWERNOW_K8)		+= powernow-k8.o
 obj-$(CONFIG_X86_PCC_CPUFREQ)		+= pcc-cpufreq.o
 obj-$(CONFIG_X86_POWERNOW_K6)		+= powernow-k6.o

drivers/cpufreq/amd-pstate-trace.c

···
+#define CREATE_TRACE_POINTS
+#include "amd-pstate-trace.h"

drivers/cpufreq/amd-pstate-trace.h

···
+/* SPDX-License-Identifier: GPL-2.0 */
+/*
+ * amd-pstate-trace.h - AMD Processor P-state Frequency Driver Tracer
+ *
+ * Copyright (C) 2021 Advanced Micro Devices, Inc. All Rights Reserved.
+ *
+ * Author: Huang Rui <[e-mail]>
+ */
+
+#if !defined(_AMD_PSTATE_TRACE_H) || defined(TRACE_HEADER_MULTI_READ)
+#define _AMD_PSTATE_TRACE_H
+
+#include <linux/cpufreq.h>
+#include <linux/tracepoint.h>
+#include <linux/trace_events.h>
+
+#undef TRACE_SYSTEM
+#define TRACE_SYSTEM amd_cpu
+
+#undef TRACE_INCLUDE_FILE
+#define TRACE_INCLUDE_FILE amd-pstate-trace
+
+#define TPS(x)  tracepoint_string(x)
+
+TRACE_EVENT(amd_pstate_perf,
+
+	TP_PROTO(unsigned long min_perf,
+		 unsigned long target_perf,
+		 unsigned long capacity,
+		 unsigned int cpu_id,
+		 bool changed,
+		 bool fast_switch
+		 ),
+
+	TP_ARGS(min_perf,
+		target_perf,
+		capacity,
+		cpu_id,
+		changed,
+		fast_switch
+		),
+
+	TP_STRUCT__entry(
+		__field(unsigned long, min_perf)
+		__field(unsigned long, target_perf)
+		__field(unsigned long, capacity)
+		__field(unsigned int, cpu_id)
+		__field(bool, changed)
+		__field(bool, fast_switch)
+		),
+
+	TP_fast_assign(
+		__entry->min_perf = min_perf;
+		__entry->target_perf = target_perf;
+		__entry->capacity = capacity;
+		__entry->cpu_id = cpu_id;
+		__entry->changed = changed;
+		__entry->fast_switch = fast_switch;
+		),
+
+	TP_printk("amd_min_perf=%lu amd_des_perf=%lu amd_max_perf=%lu cpu_id=%u changed=%s fast_switch=%s",
+		  (unsigned long)__entry->min_perf,
+		  (unsigned long)__entry->target_perf,
+		  (unsigned long)__entry->capacity,
+		  (unsigned int)__entry->cpu_id,
+		  (__entry->changed) ? "true" : "false",
+		  (__entry->fast_switch) ? "true" : "false"
+		 )
+);
+
+#endif /* _AMD_PSTATE_TRACE_H */
+
+/* This part must be outside protection */
+#undef TRACE_INCLUDE_PATH
+#define TRACE_INCLUDE_PATH .
+
+#include <trace/define_trace.h>

drivers/cpufreq/amd-pstate.c

···
 #include <asm/processor.h>
 #include <asm/cpufeature.h>
 #include <asm/cpu_device_id.h>
+#include "amd-pstate-trace.h"
 
 #define AMD_PSTATE_TRANSITION_LATENCY	0x20000
 #define AMD_PSTATE_TRANSITION_DELAY	500
···
 
 	value &= ~AMD_CPPC_MAX_PERF(~0L);
 	value |= AMD_CPPC_MAX_PERF(max_perf);
+
+	trace_amd_pstate_perf(min_perf, des_perf, max_perf,
+			      cpudata->cpu, (value != prev), fast_switch);
 
 	if (value == prev)
 		return;