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Subject[PATCH 7/7] cpufreq: amd-pstate: implement suspend and resume callbacks
Date
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.

Signed-off-by: Perry Yuan <Perry.Yuan@amd.com>
---
drivers/cpufreq/amd-pstate.c | 39 ++++++++++++++++++++++++++++++++++++
1 file changed, 39 insertions(+)

diff --git a/drivers/cpufreq/amd-pstate.c b/drivers/cpufreq/amd-pstate.c
index e63fed39f90c..749083d28b05 100644
--- a/drivers/cpufreq/amd-pstate.c
+++ b/drivers/cpufreq/amd-pstate.c
@@ -1476,6 +1476,43 @@ static int amd_pstate_epp_cpu_offline(struct cpufreq_policy *policy)
return amd_pstate_cpu_offline(policy);
}

+static int amd_pstate_epp_suspend(struct cpufreq_policy *policy)
+{
+ struct amd_cpudata *cpudata = all_cpu_data[policy->cpu];
+ int ret;
+
+ pr_debug("AMD CPU Core %d suspending\n", cpudata->cpu);
+
+ cpudata->suspended = true;
+
+ /* disable CPPC in lowlevel firmware */
+ ret = amd_pstate_enable(false);
+ if (ret)
+ pr_err("failed to disable amd pstate during suspend, return %d\n", ret);
+
+ return 0;
+}
+
+static int amd_pstate_epp_resume(struct cpufreq_policy *policy)
+{
+ struct amd_cpudata *cpudata = all_cpu_data[policy->cpu];
+
+ pr_debug("AMD CPU Core %d resuming\n", cpudata->cpu);
+
+ if (cpudata->suspended && epp_enabled) {
+ 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 void amd_pstate_verify_cpu_policy(struct amd_cpudata *cpudata,
struct cpufreq_policy_data *policy)
{
@@ -1512,6 +1549,8 @@ static struct cpufreq_driver amd_pstate_epp_driver = {
.update_limits = amd_pstate_epp_update_limits,
.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
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