[PATCH V4 2/2] cpufreq: scmi: Register for limit change notifications

[Sibi Sankar <quic_sibis@xxxxxxxxxxx>]

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@xxxxxxxxxxx>
---

v4:
* Use a interim variable to show the khz calc. [Lukasz]
* Use driver_data to pass on the handle and scmi_dev instead of using
  global variables. Dropped Lukasz's Rb due to adding these minor
  changes.

 drivers/cpufreq/scmi-cpufreq.c | 44 ++++++++++++++++++++++++++++++++++
 1 file changed, 44 insertions(+)

diff --git a/drivers/cpufreq/scmi-cpufreq.c b/drivers/cpufreq/scmi-cpufreq.c
index 3b4f6bfb2f4c..d946b7a08258 100644
--- a/drivers/cpufreq/scmi-cpufreq.c
+++ b/drivers/cpufreq/scmi-cpufreq.c
@@ -21,11 +21,18 @@
 #include <linux/types.h>
 #include <linux/units.h>
 
+struct scmi_cpufreq_driver_data {
+	struct scmi_device *sdev;
+	const struct scmi_handle *handle;
+};
+
 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;
 };
 
 static struct scmi_protocol_handle *ph;
@@ -174,6 +181,22 @@ 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;
+
+	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);
+
+	cpufreq_update_pressure(policy);
+
+	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_cpufreq_driver_data *data = cpufreq_get_driver_data();
 
 	cpu_dev = get_cpu_device(policy->cpu);
 	if (!cpu_dev) {
@@ -294,6 +318,17 @@ static int scmi_cpufreq_init(struct cpufreq_policy *policy)
 		}
 	}
 
+	priv->limit_notify_nb.notifier_call = scmi_limit_notify_cb;
+	ret = data->handle->notify_ops->devm_event_notifier_register(data->sdev, 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;
 
 out_free_opp:
@@ -366,12 +401,21 @@ static int scmi_cpufreq_probe(struct scmi_device *sdev)
 	int ret;
 	struct device *dev = &sdev->dev;
 	const struct scmi_handle *handle;
+	struct scmi_cpufreq_driver_data *data;
 
 	handle = sdev->handle;
 
 	if (!handle)
 		return -ENODEV;
 
+	data = devm_kzalloc(dev, sizeof(*data), GFP_KERNEL);
+	if (!data)
+		return -ENOMEM;
+
+	data->sdev = sdev;
+	data->handle = handle;
+	scmi_cpufreq_driver.driver_data = data;
+
 	perf_ops = handle->devm_protocol_get(sdev, SCMI_PROTOCOL_PERF, &ph);
 	if (IS_ERR(perf_ops))
 		return PTR_ERR(perf_ops);
-- 
2.34.1