[PATCH V2 4/4] cpufreq: scmi: Register for limit change notifications

[Sibi Sankar <quic_sibis@xxxxxxxxxxx>]

Register for limit change notifications if supported with the help of
perf_notify_support interface and determine the throttled frequency
using the perf_freq_xlate to apply HW pressure.

Signed-off-by: Sibi Sankar <quic_sibis@xxxxxxxxxxx>
---

v2:
* Export cpufreq_update_pressure and use it directly [Lukasz]

 drivers/cpufreq/scmi-cpufreq.c | 42 +++++++++++++++++++++++++++++++++-
 1 file changed, 41 insertions(+), 1 deletion(-)

diff --git a/drivers/cpufreq/scmi-cpufreq.c b/drivers/cpufreq/scmi-cpufreq.c
index 4ee23f4ebf4a..e0aa85764451 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;
 
@@ -144,6 +148,22 @@ scmi_get_cpu_power(struct device *cpu_dev, unsigned long *power,
 	return 0;
 }
 
+static int scmi_limit_notify_cb(struct notifier_block *nb, unsigned long event, void *data)
+{
+	unsigned long freq_hz;
+	struct scmi_perf_limits_report *limit_notify = data;
+	struct scmi_data *priv = container_of(nb, struct scmi_data, limit_notify_nb);
+	struct cpufreq_policy *policy = priv->policy;
+
+	if (perf_ops->perf_freq_xlate(ph, priv->domain_id, limit_notify->range_max, &freq_hz))
+		return NOTIFY_OK;
+
+	policy->max = freq_hz / HZ_PER_KHZ;
+	cpufreq_update_pressure(policy);
+
+	return NOTIFY_OK;
+}
+
 static int scmi_cpufreq_init(struct cpufreq_policy *policy)
 {
 	int ret, nr_opp, domain;
@@ -151,6 +171,7 @@ 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_perf_notify_info info = {};
 
 	cpu_dev = get_cpu_device(policy->cpu);
 	if (!cpu_dev) {
@@ -250,6 +271,25 @@ static int scmi_cpufreq_init(struct cpufreq_policy *policy)
 	policy->fast_switch_possible =
 		perf_ops->fast_switch_possible(ph, domain);
 
+	ret = perf_ops->perf_notify_support(ph, domain, &info);
+	if (ret)
+		dev_warn(cpu_dev, "failed to get supported notifications: %d\n", ret);
+
+	if (info.perf_limit_notify) {
+		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_err(cpu_dev, "Error in registering limit change notifier for domain %d\n",
+				domain);
+			return ret;
+		}
+	}
+
+	priv->policy = policy;
+
 	return 0;
 
 out_free_opp:
@@ -321,8 +361,8 @@ 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