[PATCH v10 07/12] cpufreq: amd-pstate: implement suspend and resume callbacks

Perry Yuan
2023-01-06T06:16:08Z

From: Perry Yuan <Perry.Yuan@amd.com>

add suspend and resume support for the AMD processors by amd_pstate_epp
driver instance.

When the CPPC is suspended, EPP driver will set EPP profile to 'power'
profile and set max/min perf to lowest perf value.
When resume happens, it will restore the MSR registers with
previous cached value.

Acked-by: Huang Rui <ray.huang@amd.com>
Reviewed-by: Mario Limonciello <Mario.Limonciello@amd.com>
Signed-off-by: Perry Yuan <Perry.Yuan@amd.com>
---
drivers/cpufreq/amd-pstate.c | 40 ++++++++++++++++++++++++++++++++++++
1 file changed, 40 insertions(+)

diff --git a/drivers/cpufreq/amd-pstate.c b/drivers/cpufreq/amd-pstate.c
index ae6d2bf18e16..2c8b126cec5a 100644
--- a/drivers/cpufreq/amd-pstate.c
+++ b/drivers/cpufreq/amd-pstate.c
@@ -1040,6 +1040,44 @@ static int amd_pstate_epp_verify_policy(struct cpufreq_policy_data *policy)
return 0;
}

+static int amd_pstate_epp_suspend(struct cpufreq_policy *policy)
+{
+ struct amd_cpudata *cpudata = policy->driver_data;
+ int ret;
+
+ /* avoid suspending when EPP is not enabled */
+ if (cppc_state != AMD_PSTATE_ACTIVE)
+ return 0;
+
+ /* set this flag to avoid setting core offline*/
+ cpudata->suspended = true;
+
+ /* disable CPPC in lowlevel firmware */
+ ret = amd_pstate_enable(false);
+ if (ret)
+ pr_err("failed to suspend, return %d\n", ret);
+
+ return 0;
+}
+
+static int amd_pstate_epp_resume(struct cpufreq_policy *policy)
+{
+ struct amd_cpudata *cpudata = policy->driver_data;
+
+ if (cpudata->suspended) {
+ mutex_lock(&amd_pstate_limits_lock);
+
+ /* enable amd pstate from suspend state*/
+ amd_pstate_epp_reenable(cpudata);
+
+ mutex_unlock(&amd_pstate_limits_lock);
+
+ cpudata->suspended = false;
+ }
+
+ return 0;
+}
+
static struct cpufreq_driver amd_pstate_driver = {
.flags = CPUFREQ_CONST_LOOPS | CPUFREQ_NEED_UPDATE_LIMITS,
.verify = amd_pstate_verify,
@@ -1061,6 +1099,8 @@ static struct cpufreq_driver amd_pstate_epp_driver = {
.exit = amd_pstate_epp_cpu_exit,
.offline = amd_pstate_epp_cpu_offline,
.online = amd_pstate_epp_cpu_online,
+ .suspend = amd_pstate_epp_suspend,
+ .resume = amd_pstate_epp_resume,
.name = "amd_pstate_epp",
.attr = amd_pstate_epp_attr,
};
--
2.34.1