cpupower: Add EPP value change support

amd_pstate and intel_pstate active mode drivers support energy
performance preference feature. Through this user can convey it's
energy/performance preference to platform. Add this value change
capability to cpupower.

To change the EPP value use below command:
cpupower set --epp performance

Reviewed-by: Mario Limonciello <mario.limonciello@amd.com>
Signed-off-by: Wyes Karny <wyes.karny@amd.com>
Tested-by: Perry Yuan <Perry.Yuan@amd.com>
Acked-by: Huang Rui <ray.huang@amd.com>
Signed-off-by: Shuah Khan <skhan@linuxfoundation.org>

tools/power/cpupower/utils/cpupower-set.c

@@ -18,6 +18,7 @@
 
 static struct option set_opts[] = {
 	{"perf-bias", required_argument, NULL, 'b'},
+	{"epp", required_argument, NULL, 'e'},
 	{ },
 };
 
@@ -37,11 +38,13 @@ int cmd_set(int argc, char **argv)
 	union {
 		struct {
 			int perf_bias:1;
+			int epp:1;
 		};
 		int params;
 	} params;
 	int perf_bias = 0;
 	int ret = 0;
+	char epp[30];
 
 	ret = uname(&uts);
 	if (!ret && (!strcmp(uts.machine, "ppc64le") ||
@@ -55,7 +58,7 @@ int cmd_set(int argc, char **argv)
 
 	params.params = 0;
 	/* parameter parsing */
-	while ((ret = getopt_long(argc, argv, "b:",
+	while ((ret = getopt_long(argc, argv, "b:e:",
 						set_opts, NULL)) != -1) {
 		switch (ret) {
 		case 'b':
@@ -69,6 +72,15 @@ int cmd_set(int argc, char **argv)
 			}
 			params.perf_bias = 1;
 			break;
+		case 'e':
+			if (params.epp)
+				print_wrong_arg_exit();
+			if (sscanf(optarg, "%29s", epp) != 1) {
+				print_wrong_arg_exit();
+				return -EINVAL;
+			}
+			params.epp = 1;
+			break;
 		default:
 			print_wrong_arg_exit();
 		}
@@ -102,6 +114,15 @@ int cmd_set(int argc, char **argv)
 				break;
 			}
 		}
+
+		if (params.epp) {
+			ret = cpupower_set_epp(cpu, epp);
+			if (ret) {
+				fprintf(stderr,
+					"Error setting epp value on CPU %d\n", cpu);
+				break;
+			}
+		}
 	}
 	return ret;
 }

tools/power/cpupower/utils/helpers/helpers.h

@@ -116,6 +116,8 @@ extern int cpupower_intel_set_perf_bias(unsigned int cpu, unsigned int val);
 extern int cpupower_intel_get_perf_bias(unsigned int cpu);
 extern unsigned long long msr_intel_get_turbo_ratio(unsigned int cpu);
 
+extern int cpupower_set_epp(unsigned int cpu, char *epp);
+
 /* Read/Write msr ****************************/
 
 /* PCI stuff ****************************/
@@ -173,6 +175,9 @@ static inline int cpupower_intel_get_perf_bias(unsigned int cpu)
 static inline unsigned long long msr_intel_get_turbo_ratio(unsigned int cpu)
 { return 0; };
 
+static inline int cpupower_set_epp(unsigned int cpu, char *epp)
+{ return -1; };
+
 /* Read/Write msr ****************************/
 
 static inline int cpufreq_has_boost_support(unsigned int cpu, int *support,

tools/power/cpupower/utils/helpers/misc.c

@@ -87,6 +87,25 @@ int cpupower_intel_set_perf_bias(unsigned int cpu, unsigned int val)
 	return 0;
 }
 
+int cpupower_set_epp(unsigned int cpu, char *epp)
+{
+	char path[SYSFS_PATH_MAX];
+	char linebuf[30] = {};
+
+	snprintf(path, sizeof(path),
+		PATH_TO_CPU "cpu%u/cpufreq/energy_performance_preference", cpu);
+
+	if (!is_valid_path(path))
+		return -1;
+
+	snprintf(linebuf, sizeof(linebuf), "%s", epp);
+
+	if (cpupower_write_sysfs(path, linebuf, 30) <= 0)
+		return -1;
+
+	return 0;
+}
+
 bool cpupower_amd_pstate_enabled(void)
 {
 	char *driver = cpufreq_get_driver(0);