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From:   Perry Yuan <perry.yuan@amd.com>
To:     <rafael.j.wysocki@intel.com>, <Mario.Limonciello@amd.com>,
        <ray.huang@amd.com>, <viresh.kumar@linaro.org>
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Subject: [PATCH v5 5/9] cpufreq: amd-pstate: implement suspend and resume callbacks
Date:   Tue, 29 Nov 2022 01:03:10 +0800
Message-ID: <20221128170314.2276636-6-perry.yuan@amd.com>
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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.

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 b77f5b1f3565..3626ae1e8f9a 100644
--- a/drivers/cpufreq/amd-pstate.c
+++ b/drivers/cpufreq/amd-pstate.c
@@ -1270,6 +1270,44 @@ 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;
+
+	/* avoid suspending when EPP is not enabled */
+	if (!cppc_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 = all_cpu_data[policy->cpu];
+
+	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 void amd_pstate_verify_cpu_policy(struct amd_cpudata *cpudata,
 					   struct cpufreq_policy_data *policy)
 {
@@ -1306,6 +1344,8 @@ 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