linux-kernel - [PATCH 1/2] firmware: arm_scmi: Add fast_switch

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Date:   Wed, 17 Jun 2020 10:43:31 +0100
From:   Nicola Mazzucato <nicola.mazzucato@....com>
To:     linux-kernel@...r.kernel.org, sudeep.holla@....com,
        rjw@...ysocki.net, viresh.kumar@...aro.org,
        linux-arm-kernel@...ts.infradead.org, linux-pm@...r.kernel.org
Cc:     lukasz.luba@....com
Subject: [PATCH 1/2] firmware: arm_scmi: Add fast_switch_possible() api

Add a new fast_switch_possible interface to the existing
perf_ops api to export the information of whether or not
fast_switch is possible in this driver.

This can be used by the CPUFreq driver and framework to
choose proper mechanism for frequency change.

Suggested-by: Lukasz Luba <lukasz.luba@....com>
Signed-off-by: Nicola Mazzucato <nicola.mazzucato@....com>
---
 drivers/firmware/arm_scmi/perf.c | 12 ++++++++++++
 include/linux/scmi_protocol.h    |  2 ++
 2 files changed, 14 insertions(+)

diff --git a/drivers/firmware/arm_scmi/perf.c b/drivers/firmware/arm_scmi/perf.c
index eadc171e254b..ef747a9bb948 100644
--- a/drivers/firmware/arm_scmi/perf.c
+++ b/drivers/firmware/arm_scmi/perf.c
@@ -697,6 +697,17 @@ static int scmi_dvfs_est_power_get(const struct scmi_handle *handle, u32 domain,
 	return ret;
 }
 
+static bool scmi_fast_switch_possible(const struct scmi_handle *handle,
+				   struct device *dev)
+{
+	struct perf_dom_info *dom;
+	struct scmi_perf_info *pi = handle->perf_priv;
+
+	dom = pi->dom_info + scmi_dev_domain_id(dev);
+
+	return (dom->fc_info && dom->fc_info->level_set_addr);
+}
+
 static struct scmi_perf_ops perf_ops = {
 	.limits_set = scmi_perf_limits_set,
 	.limits_get = scmi_perf_limits_get,
@@ -708,6 +719,7 @@ static struct scmi_perf_ops perf_ops = {
 	.freq_set = scmi_dvfs_freq_set,
 	.freq_get = scmi_dvfs_freq_get,
 	.est_power_get = scmi_dvfs_est_power_get,
+	.fast_switch_possible = scmi_fast_switch_possible,
 };
 
 static int scmi_perf_protocol_init(struct scmi_handle *handle)
diff --git a/include/linux/scmi_protocol.h b/include/linux/scmi_protocol.h
index ce2f5c28b2df..19e50b89117e 100644
--- a/include/linux/scmi_protocol.h
+++ b/include/linux/scmi_protocol.h
@@ -118,6 +118,8 @@ struct scmi_perf_ops {
 			unsigned long *rate, bool poll);
 	int (*est_power_get)(const struct scmi_handle *handle, u32 domain,
 			     unsigned long *rate, unsigned long *power);
+	bool (*fast_switch_possible)(const struct scmi_handle *handle,
+			struct device *dev);
 };
 
 /**
-- 
2.27.0