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Subject[PATCH v3 22/22] cpufreq: scmi: add support for fast frequency switching
Date
The cpufreq core provides option for drivers to implement fast_switch
callback which is invoked for frequency switching from interrupt context.

This patch adds support for fast_switch callback in SCMI cpufreq driver
by making use of polling based SCMI transfer. It also sets the flag
fast_switch_possible.

Cc: "Rafael J. Wysocki" <rjw@rjwysocki.net>
Cc: Viresh Kumar <viresh.kumar@linaro.org>
Cc: linux-pm@vger.kernel.org
Signed-off-by: Sudeep Holla <sudeep.holla@arm.com>
---
drivers/cpufreq/scmi-cpufreq.c | 16 ++++++++++++++++
1 file changed, 16 insertions(+)

diff --git a/drivers/cpufreq/scmi-cpufreq.c b/drivers/cpufreq/scmi-cpufreq.c
index bc5385638eb4..067a39bd5167 100644
--- a/drivers/cpufreq/scmi-cpufreq.c
+++ b/drivers/cpufreq/scmi-cpufreq.c
@@ -65,6 +65,19 @@ scmi_cpufreq_set_target(struct cpufreq_policy *policy, unsigned int index)
return perf_ops->freq_set(handle, priv->domain_id, freq, false);
}

+static unsigned int scmi_cpufreq_fast_switch(struct cpufreq_policy *policy,
+ unsigned int target_freq)
+{
+ struct scmi_data *priv = policy->driver_data;
+ struct scmi_perf_ops *perf_ops = handle->perf_ops;
+
+ if (!perf_ops->freq_set(handle, priv->domain_id,
+ target_freq * 1000, true))
+ return target_freq;
+
+ return 0;
+}
+
static int
scmi_get_sharing_cpus(struct device *cpu_dev, struct cpumask *cpumask)
{
@@ -168,6 +181,7 @@ static int scmi_cpufreq_init(struct cpufreq_policy *policy)

policy->cpuinfo.transition_latency = latency;

+ policy->fast_switch_possible = true;
return 0;

out_free_cpufreq_table:
@@ -184,6 +198,7 @@ static int scmi_cpufreq_exit(struct cpufreq_policy *policy)
{
struct scmi_data *priv = policy->driver_data;

+ policy->fast_switch_possible = false;
cpufreq_cooling_unregister(priv->cdev);
dev_pm_opp_free_cpufreq_table(priv->cpu_dev, &policy->freq_table);
kfree(priv);
@@ -227,6 +242,7 @@ static struct cpufreq_driver scmi_cpufreq_driver = {
.verify = cpufreq_generic_frequency_table_verify,
.attr = cpufreq_generic_attr,
.target_index = scmi_cpufreq_set_target,
+ .fast_switch = scmi_cpufreq_fast_switch,
.get = scmi_cpufreq_get_rate,
.init = scmi_cpufreq_init,
.exit = scmi_cpufreq_exit,
--
2.7.4
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