[PATCH 4/4] cpufreq: scmi: Read statistics from FW shared memory

Lukasz Luba
2020-07-29T15:12:34Z

Add support for reading CPUFreq statistics from the firmware. The setup
code initializes needed structures per domain basis. The driver callback
scmi_cpufreq_stats_get is called by the CPUFreq framework and invokes
SCMI performance protocol in order to retrieve latest statistics.

Signed-off-by: Lukasz Luba <lukasz.luba@arm.com>
---
drivers/cpufreq/scmi-cpufreq.c | 80 ++++++++++++++++++++++++++++++++++
1 file changed, 80 insertions(+)

diff --git a/drivers/cpufreq/scmi-cpufreq.c b/drivers/cpufreq/scmi-cpufreq.c
index fe95350eb844..67ae63171dd0 100644
--- a/drivers/cpufreq/scmi-cpufreq.c
+++ b/drivers/cpufreq/scmi-cpufreq.c
@@ -22,6 +22,7 @@
struct scmi_data {
int domain_id;
struct device *cpu_dev;
+ struct scmi_perf_domain_stats *stats;
};

static unsigned int scmi_cpufreq_get_rate(unsigned int cpu);
@@ -48,6 +49,34 @@ static struct cpufreq_driver scmi_cpufreq_driver = {

static const struct scmi_handle *handle;

+static int scmi_cpufreq_stats_get(struct cpufreq_policy *policy)
+{
+ struct scmi_data *priv = policy->driver_data;
+ struct cpufreq_stats *stats = policy->stats;
+ int i, ret;
+
+ /*
+ * Since the driver callback is global and can be set for all
+ * policy objects, there is a need to check if that policy has
+ * statistics in the shared memory.
+ */
+ if (!policy->has_driver_stats)
+ return -EINVAL;
+
+ ret = handle->perf_ops->statistics_get(handle, priv->domain_id, priv->stats);
+ if (ret)
+ return ret;
+
+ for (i = 0; i < priv->stats->state_num; i++)
+ stats->time_in_state[i] = priv->stats->time_in_state[i];
+
+ stats->total_trans = priv->stats->total_trans;
+ stats->last_index = priv->stats->last_index;
+ stats->last_time = priv->stats->last_time;
+
+ return ret;
+}
+
static unsigned int scmi_cpufreq_get_rate(unsigned int cpu)
{
struct cpufreq_policy *policy = cpufreq_cpu_get_raw(cpu);
@@ -147,6 +176,45 @@ scmi_get_cpu_power(unsigned long *power, unsigned long *KHz,
return 0;
}

+static int scmi_cpufreq_stats_init(struct cpufreq_policy *policy,
+ struct scmi_data *priv, int nr_opp)
+{
+ struct scmi_perf_domain_stats *stats;
+ int ret;
+
+ stats = kzalloc(sizeof(struct scmi_perf_domain_stats), GFP_KERNEL);
+ if (!stats)
+ return -ENOMEM;
+
+ stats->time_in_state = kcalloc(nr_opp, sizeof(u64), GFP_KERNEL);
+ if (!stats->time_in_state) {
+ kfree(stats);
+ return -ENOMEM;
+ }
+
+ stats->freq_table = kcalloc(nr_opp, sizeof(unsigned int), GFP_KERNEL);
+ if (!stats->freq_table) {
+ kfree(stats->time_in_state);
+ kfree(stats);
+ return -ENOMEM;
+ }
+
+ priv->stats = stats;
+ priv->stats->state_num = nr_opp;
+ policy->has_driver_stats = true;
+ scmi_cpufreq_driver.get_statistics = scmi_cpufreq_stats_get;
+
+ ret = handle->perf_ops->statistics_get(handle, priv->domain_id, stats);
+ if (ret) {
+ kfree(stats->freq_table);
+ kfree(stats->time_in_state);
+ kfree(stats);
+ policy->has_driver_stats = false;
+ }
+
+ return ret;
+}
+
static int scmi_cpufreq_init(struct cpufreq_policy *policy)
{
int ret, nr_opp;
@@ -209,6 +277,10 @@ static int scmi_cpufreq_init(struct cpufreq_policy *policy)
/* SCMI allows DVFS request for any domain from any CPU */
policy->dvfs_possible_from_any_cpu = true;

+ ret = scmi_cpufreq_stats_init(policy, priv, nr_opp);
+ if (ret)
+ dev_warn(cpu_dev, "failed to init statistics: %d\n", ret);
+
latency = handle->perf_ops->transition_latency_get(handle, cpu_dev);
if (!latency)
latency = CPUFREQ_ETERNAL;
@@ -236,6 +308,14 @@ static int scmi_cpufreq_exit(struct cpufreq_policy *policy)

dev_pm_opp_free_cpufreq_table(priv->cpu_dev, &policy->freq_table);
dev_pm_opp_remove_all_dynamic(priv->cpu_dev);
+
+ if (priv->stats) {
+ policy->has_driver_stats = false;
+ kfree(priv->stats->time_in_state);
+ kfree(priv->stats->freq_table);
+ kfree(priv->stats);
+ }
+
kfree(priv);

return 0;
--
2.17.1