linux-kernel - [PATCH V7 2/2] cpufreq: scmi: Register for limit change notifications

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Message-ID: <20241031132745.3765612-3-quic_sibis@quicinc.com>
Date: Thu, 31 Oct 2024 18:57:45 +0530
From: Sibi Sankar <quic_sibis@...cinc.com>
To: <sudeep.holla@....com>, <cristian.marussi@....com>, <rafael@...nel.org>,
        <viresh.kumar@...aro.org>, <morten.rasmussen@....com>,
        <dietmar.eggemann@....com>, <lukasz.luba@....com>,
        <pierre.gondois@....com>, <vincent.guittot@...aro.org>
CC: <linux-arm-kernel@...ts.infradead.org>, <linux-pm@...r.kernel.org>,
        <linux-kernel@...r.kernel.org>, <quic_mdtipton@...cinc.com>,
        <linux-arm-msm@...r.kernel.org>, Sibi Sankar <quic_sibis@...cinc.com>
Subject: [PATCH V7 2/2] cpufreq: scmi: Register for limit change notifications

Register for limit change notifications if supported and use the throttled
frequency from the notification to apply HW pressure.

Signed-off-by: Sibi Sankar <quic_sibis@...cinc.com>
Tested-by: Mike Tipton <quic_mdtipton@...cinc.com>
Reviewed-by: Cristian Marussi <cristian.marussi@....com>
Reviewed-by: Lukasz Luba <lukasz.luba@....com>
---

v7:
* Add a new request instead of reusing the max_freq_req [Vincent]
* Use the non-devm versions of register/unregister of event notifier
  since we have to remove them when the cpus get removed anyway.
* Add new patch to fix cleanup path on boost enablement failure.

 drivers/cpufreq/scmi-cpufreq.c | 51 ++++++++++++++++++++++++++++++++++
 1 file changed, 51 insertions(+)

diff --git a/drivers/cpufreq/scmi-cpufreq.c b/drivers/cpufreq/scmi-cpufreq.c
index 07d6f9a9b7c8..ff13f7d4b2c9 100644
--- a/drivers/cpufreq/scmi-cpufreq.c
+++ b/drivers/cpufreq/scmi-cpufreq.c
@@ -16,6 +16,7 @@
 #include <linux/export.h>
 #include <linux/module.h>
 #include <linux/pm_opp.h>
+#include <linux/pm_qos.h>
 #include <linux/slab.h>
 #include <linux/scmi_protocol.h>
 #include <linux/types.h>
@@ -25,7 +26,10 @@ struct scmi_data {
 	int domain_id;
 	int nr_opp;
 	struct device *cpu_dev;
+	struct cpufreq_policy *policy;
 	cpumask_var_t opp_shared_cpus;
+	struct notifier_block limit_notify_nb;
+	struct freq_qos_request	limits_freq_req;
 };
 
 static struct scmi_protocol_handle *ph;
@@ -174,6 +178,25 @@ static struct freq_attr *scmi_cpufreq_hw_attr[] = {
 	NULL,
 };
 
+static int scmi_limit_notify_cb(struct notifier_block *nb, unsigned long event, void *data)
+{
+	struct scmi_data *priv = container_of(nb, struct scmi_data, limit_notify_nb);
+	struct scmi_perf_limits_report *limit_notify = data;
+	struct cpufreq_policy *policy = priv->policy;
+	unsigned int limit_freq_khz;
+	int ret;
+
+	limit_freq_khz = limit_notify->range_max_freq / HZ_PER_KHZ;
+
+	policy->max = clamp(limit_freq_khz, policy->cpuinfo.min_freq, policy->cpuinfo.max_freq);
+
+	ret = freq_qos_update_request(&priv->limits_freq_req, policy->max);
+	if (ret < 0)
+		pr_warn("failed to update freq constraint: %d\n", ret);
+
+	return NOTIFY_OK;
+}
+
 static int scmi_cpufreq_init(struct cpufreq_policy *policy)
 {
 	int ret, nr_opp, domain;
@@ -181,6 +204,7 @@ static int scmi_cpufreq_init(struct cpufreq_policy *policy)
 	struct device *cpu_dev;
 	struct scmi_data *priv;
 	struct cpufreq_frequency_table *freq_table;
+	struct scmi_device *sdev = cpufreq_get_driver_data();
 
 	cpu_dev = get_cpu_device(policy->cpu);
 	if (!cpu_dev) {
@@ -294,6 +318,25 @@ static int scmi_cpufreq_init(struct cpufreq_policy *policy)
 		}
 	}
 
+	ret = freq_qos_add_request(&policy->constraints, &priv->limits_freq_req, FREQ_QOS_MAX,
+				   FREQ_QOS_MAX_DEFAULT_VALUE);
+	if (ret < 0) {
+		dev_err(cpu_dev, "failed to add qos limits request: %d\n", ret);
+		goto out_free_table;
+	}
+
+	priv->limit_notify_nb.notifier_call = scmi_limit_notify_cb;
+	ret = sdev->handle->notify_ops->event_notifier_register(sdev->handle, SCMI_PROTOCOL_PERF,
+							SCMI_EVENT_PERFORMANCE_LIMITS_CHANGED,
+							&priv->domain_id,
+							&priv->limit_notify_nb);
+	if (ret)
+		dev_warn(&sdev->dev,
+			 "failed to register for limits change notifier for domain %d\n",
+			 priv->domain_id);
+
+	priv->policy = policy;
+
 	return 0;
 
 out_free_table:
@@ -313,7 +356,13 @@ static int scmi_cpufreq_init(struct cpufreq_policy *policy)
 static void scmi_cpufreq_exit(struct cpufreq_policy *policy)
 {
 	struct scmi_data *priv = policy->driver_data;
+	struct scmi_device *sdev = cpufreq_get_driver_data();
 
+	sdev->handle->notify_ops->event_notifier_unregister(sdev->handle, SCMI_PROTOCOL_PERF,
+							    SCMI_EVENT_PERFORMANCE_LIMITS_CHANGED,
+							    &priv->domain_id,
+							    &priv->limit_notify_nb);
+	freq_qos_remove_request(&priv->limits_freq_req);
 	dev_pm_opp_free_cpufreq_table(priv->cpu_dev, &policy->freq_table);
 	dev_pm_opp_remove_all_dynamic(priv->cpu_dev);
 	free_cpumask_var(priv->opp_shared_cpus);
@@ -372,6 +421,8 @@ static int scmi_cpufreq_probe(struct scmi_device *sdev)
 	if (!handle)
 		return -ENODEV;
 
+	scmi_cpufreq_driver.driver_data = sdev;
+
 	perf_ops = handle->devm_protocol_get(sdev, SCMI_PROTOCOL_PERF, &ph);
 	if (IS_ERR(perf_ops))
 		return PTR_ERR(perf_ops);
-- 
2.34.1