[PATCH 4/7] cpufreq: amd_pstate: add AMD pstate EPP support for shared memory type processor

[Perry Yuan <Perry.Yuan@amd.com>]

Add Energy Performance Preference support for AMD SOCs which only
support the shared memory interface that implemented on Zen2 and Zen3
processors, because this type CPU has no MSR supported, it will use
ACPI PCC channel to enable EPP and reset desired perf to be zero.

Signed-off-by: Perry Yuan <Perry.Yuan@amd.com>
---
 drivers/cpufreq/amd-pstate.c | 12 ++++++++++++
 1 file changed, 12 insertions(+)

diff --git a/drivers/cpufreq/amd-pstate.c b/drivers/cpufreq/amd-pstate.c
index 451295284a26..fff298744a8e 100644
--- a/drivers/cpufreq/amd-pstate.c
+++ b/drivers/cpufreq/amd-pstate.c
@@ -133,12 +133,24 @@ static inline int pstate_enable(bool enable)
 
 static int cppc_enable(bool enable)
 {
+	struct cppc_perf_ctrls perf_ctrls;
 	int cpu, ret = 0;
 
 	for_each_present_cpu(cpu) {
 		ret = cppc_set_enable(cpu, enable);
 		if (ret)
 			return ret;
+
+	/* Enable active mode for EPP */
+	ret = cppc_set_auto_epp(cpu, enable);
+	if (ret)
+		return ret;
+
+	/* Set zero to desired perf to enable EPP control*/
+	perf_ctrls.desired_perf = 0;
+	ret = cppc_set_perf(cpu, &perf_ctrls);
+	if (ret)
+		return ret;
 	}
 
 	return ret;
-- 
2.34.1