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 <[email protected]>
Signed-off-by: Wyes Karny <[email protected]>
Tested-by: Perry Yuan <[email protected]>
Acked-by: Huang Rui <[email protected]>
Signed-off-by: Shuah Khan <[email protected]>

1 files changed, 19 insertions, 0 deletions

diff --git a/tools/power/cpupower/utils/helpers/misc.c b/tools/power/cpupower/utils/helpers/misc.c
index 0c56fc77f93b..583df38ab13c 100644
--- a/tools/power/cpupower/utils/helpers/misc.c
+++ b/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);