[PATCH V3 2/2] cpufreq: scmi: Register for limit change notifications

[Sibi Sankar <quic_sibis@quicinc.com>]

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@quicinc.com>
---

v3:
* Sanitize range_max received from the notifier. [Pierre]
* Update commit message.

 drivers/cpufreq/scmi-cpufreq.c | 29 ++++++++++++++++++++++++++++-
 1 file changed, 28 insertions(+), 1 deletion(-)

diff --git a/drivers/cpufreq/scmi-cpufreq.c b/drivers/cpufreq/scmi-cpufreq.c
index 76a0ddbd9d24..78b87b72962d 100644
--- a/drivers/cpufreq/scmi-cpufreq.c
+++ b/drivers/cpufreq/scmi-cpufreq.c
@@ -25,9 +25,13 @@ 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;
 };
 
+const struct scmi_handle *handle;
+static struct scmi_device *scmi_dev;
 static struct scmi_protocol_handle *ph;
 static const struct scmi_perf_proto_ops *perf_ops;
 static struct cpufreq_driver scmi_cpufreq_driver;
@@ -151,6 +155,20 @@ 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;
+
+	policy->max = clamp(limit_notify->range_max_freq/HZ_PER_KHZ, policy->cpuinfo.min_freq,
+			    policy->cpuinfo.max_freq);
+
+	cpufreq_update_pressure(policy);
+
+	return NOTIFY_OK;
+}
+
 static int scmi_cpufreq_init(struct cpufreq_policy *policy)
 {
 	int ret, nr_opp, domain;
@@ -269,6 +287,15 @@ static int scmi_cpufreq_init(struct cpufreq_policy *policy)
 		}
 	}
 
+	priv->limit_notify_nb.notifier_call = scmi_limit_notify_cb;
+	ret = handle->notify_ops->devm_event_notifier_register(scmi_dev, SCMI_PROTOCOL_PERF,
+							SCMI_EVENT_PERFORMANCE_LIMITS_CHANGED,
+							&domain,
+							&priv->limit_notify_nb);
+	if (ret)
+		dev_warn(cpu_dev,
+			 "failed to register for limits change notifier for domain %d\n", domain);
+
 	priv->policy = policy;
 
 	return 0;
@@ -342,8 +369,8 @@ static int scmi_cpufreq_probe(struct scmi_device *sdev)
 {
 	int ret;
 	struct device *dev = &sdev->dev;
-	const struct scmi_handle *handle;
 
+	scmi_dev = sdev;
 	handle = sdev->handle;
 
 	if (!handle)
-- 
2.34.1