From: Viresh Kumar <viresh.kumar@...>

commit 2174344765f472895c076d703c9cdc58215e1393 upstream.

In few use cases (like: cpufreq), it is desired to get the maximum
latency for changing OPPs. Add support for that.

Signed-off-by: Viresh Kumar <viresh.kumar@...>
Reviewed-by: Stephen Boyd <sboyd@...>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@...>
Signed-off-by: Chen-Yu Tsai (Moxa) <wens@...>
---
drivers/base/power/opp/core.c | 17 +++++++++++++++++
include/linux/pm_opp.h | 6 ++++++
2 files changed, 23 insertions(+)

diff --git a/drivers/base/power/opp/core.c b/drivers/base/power/opp/core.=
c
index 09165fbef84ed..d51ddcebcca00 100644
--- a/drivers/base/power/opp/core.c
+++ b/drivers/base/power/opp/core.c
@@ -289,6 +289,23 @@ unsigned long dev_pm_opp_get_max_volt_latency(struct=
device *dev)
}
EXPORT_SYMBOL_GPL(dev_pm_opp_get_max_volt_latency);
=20
+/**
+ * dev_pm_opp_get_max_transition_latency() - Get max transition latency =
in
+ * nanoseconds
+ * @dev: device for which we do this operation
+ *
+ * Return: This function returns the max transition latency, in nanoseco=
nds, to
+ * switch from one OPP to other.
+ *
+ * Locking: This function takes rcu_read_lock().
+ */
+unsigned long dev_pm_opp_get_max_transition_latency(struct device *dev)
+{
+ return dev_pm_opp_get_max_volt_latency(dev) +
+ dev_pm_opp_get_max_clock_latency(dev);
+}
+EXPORT_SYMBOL_GPL(dev_pm_opp_get_max_transition_latency);
+
/**
* dev_pm_opp_get_suspend_opp() - Get suspend opp
* @dev: device for which we do this operation
diff --git a/include/linux/pm_opp.h b/include/linux/pm_opp.h
index 5daa43058ac10..59da3d9e11ea3 100644
--- a/include/linux/pm_opp.h
+++ b/include/linux/pm_opp.h
@@ -35,6 +35,7 @@ bool dev_pm_opp_is_turbo(struct dev_pm_opp *opp);
int dev_pm_opp_get_opp_count(struct device *dev);
unsigned long dev_pm_opp_get_max_clock_latency(struct device *dev);
unsigned long dev_pm_opp_get_max_volt_latency(struct device *dev);
+unsigned long dev_pm_opp_get_max_transition_latency(struct device *dev);
struct dev_pm_opp *dev_pm_opp_get_suspend_opp(struct device *dev);
=20
struct dev_pm_opp *dev_pm_opp_find_freq_exact(struct device *dev,
@@ -94,6 +95,11 @@ static inline unsigned long dev_pm_opp_get_max_volt_la=
tency(struct device *dev)
return 0;
}
=20
+static inline unsigned long dev_pm_opp_get_max_transition_latency(struct=
device *dev)
+{
+ return 0;
+}
+
static inline struct dev_pm_opp *dev_pm_opp_get_suspend_opp(struct devic=
e *dev)
{
return NULL;
--=20
2.27.0