cpupower: Add support for showing energy performance preference

The EPP value is useful for characterization of performance. Show
it in cpupower frequency-info output.

Link: https://lore.kernel.org/r/20241218191144.3440854-6-superm1@kernel.org
Signed-off-by: Mario Limonciello <mario.limonciello@amd.com>
Signed-off-by: Shuah Khan <skhan@linuxfoundation.org>

tools/power/cpupower/lib/cpufreq.c

@@ -127,12 +127,14 @@ static unsigned long sysfs_cpufreq_get_one_value(unsigned int cpu,
 enum cpufreq_string {
 	SCALING_DRIVER,
 	SCALING_GOVERNOR,
+	ENERGY_PERFORMANCE_PREFERENCE,
 	MAX_CPUFREQ_STRING_FILES
 };
 
 static const char *cpufreq_string_files[MAX_CPUFREQ_STRING_FILES] = {
 	[SCALING_DRIVER] = "scaling_driver",
 	[SCALING_GOVERNOR] = "scaling_governor",
+	[ENERGY_PERFORMANCE_PREFERENCE] = "energy_performance_preference",
 };
 
 
@@ -207,6 +209,18 @@ unsigned long cpufreq_get_transition_latency(unsigned int cpu)
 	return sysfs_cpufreq_get_one_value(cpu, CPUINFO_LATENCY);
 }
 
+char *cpufreq_get_energy_performance_preference(unsigned int cpu)
+{
+	return sysfs_cpufreq_get_one_string(cpu, ENERGY_PERFORMANCE_PREFERENCE);
+}
+
+void cpufreq_put_energy_performance_preference(char *ptr)
+{
+	if (!ptr)
+		return;
+	free(ptr);
+}
+
 int cpufreq_get_hardware_limits(unsigned int cpu,
 				unsigned long *min,
 				unsigned long *max)

tools/power/cpupower/lib/cpufreq.h

@@ -68,6 +68,14 @@ unsigned long cpufreq_get_freq_hardware(unsigned int cpu);
 unsigned long cpufreq_get_transition_latency(unsigned int cpu);
 
 
+/* determine energy performance preference
+ *
+ * returns NULL on failure, else the string that represents the energy performance
+ * preference requested.
+ */
+char *cpufreq_get_energy_performance_preference(unsigned int cpu);
+void cpufreq_put_energy_performance_preference(char *ptr);
+
 /* determine hardware CPU frequency limits
  *
  * These may be limited further by thermal, energy or other

tools/power/cpupower/utils/cpufreq-info.c

@@ -422,6 +422,23 @@ static int get_freq_stats(unsigned int cpu, unsigned int human)
 	return 0;
 }
 
+/* --epp / -z */
+
+static int get_epp(unsigned int cpu, bool interactive)
+{
+	char *epp;
+
+	epp = cpufreq_get_energy_performance_preference(cpu);
+	if (!epp)
+		return -EINVAL;
+	if (interactive)
+		printf(_("  energy performance preference: %s\n"), epp);
+
+	cpufreq_put_energy_performance_preference(epp);
+
+	return 0;
+}
+
 /* --latency / -y */
 
 static int get_latency(unsigned int cpu, unsigned int human)
@@ -461,6 +478,7 @@ static void debug_output_one(unsigned int cpu)
 	get_related_cpus(cpu);
 	get_affected_cpus(cpu);
 	get_latency(cpu, 1);
+	get_epp(cpu, true);
 	get_hardware_limits(cpu, 1);
 
 	freqs = cpufreq_get_available_frequencies(cpu);
@@ -501,6 +519,7 @@ static struct option info_opts[] = {
 	{"human",	 no_argument,		 NULL,	 'm'},
 	{"no-rounding", no_argument,	 NULL,	 'n'},
 	{"performance", no_argument,	 NULL,	 'c'},
+	{"epp",		 no_argument,		 NULL,	 'z'},
 	{ },
 };
 
@@ -514,7 +533,7 @@ int cmd_freq_info(int argc, char **argv)
 	int output_param = 0;
 
 	do {
-		ret = getopt_long(argc, argv, "oefwldpgrasmybnc", info_opts,
+		ret = getopt_long(argc, argv, "oefwldpgrasmybncz", info_opts,
 				  NULL);
 		switch (ret) {
 		case '?':
@@ -538,6 +557,7 @@ int cmd_freq_info(int argc, char **argv)
 		case 's':
 		case 'y':
 		case 'c':
+		case 'z':
 			if (output_param) {
 				output_param = -1;
 				cont = 0;
@@ -647,6 +667,9 @@ int cmd_freq_info(int argc, char **argv)
 		case 'c':
 			ret = get_perf_cap(cpu);
 			break;
+		case 'z':
+			ret = get_epp(cpu, true);
+			break;
 		}
 		if (ret)
 			return ret;