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

commit 655c9df961751ce21466f6e97e8033932c27a675 upstream.

In few use cases (like: cpufreq), it is desired to get the maximum
voltage 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 | 59 +++++++++++++++++++++++++++++++++++
include/linux/pm_opp.h | 6 ++++
2 files changed, 65 insertions(+)

diff --git a/drivers/base/power/opp/core.c b/drivers/base/power/opp/core.=
c
index 48ec88befffc9..09165fbef84ed 100644
--- a/drivers/base/power/opp/core.c
+++ b/drivers/base/power/opp/core.c
@@ -230,6 +230,65 @@ unsigned long dev_pm_opp_get_max_clock_latency(struc=
t device *dev)
}
EXPORT_SYMBOL_GPL(dev_pm_opp_get_max_clock_latency);
=20
+/**
+ * dev_pm_opp_get_max_volt_latency() - Get max voltage latency in nanose=
conds
+ * @dev: device for which we do this operation
+ *
+ * Return: This function returns the max voltage latency in nanoseconds.
+ *
+ * Locking: This function takes rcu_read_lock().
+ */
+unsigned long dev_pm_opp_get_max_volt_latency(struct device *dev)
+{
+ struct device_opp *dev_opp;
+ struct dev_pm_opp *opp;
+ struct regulator *reg;
+ unsigned long latency_ns =3D 0;
+ unsigned long min_uV =3D ~0, max_uV =3D 0;
+ int ret;
+
+ rcu_read_lock();
+
+ dev_opp =3D _find_device_opp(dev);
+ if (IS_ERR(dev_opp)) {
+ rcu_read_unlock();
+ return 0;
+ }
+
+ reg =3D dev_opp->regulator;
+ if (IS_ERR_OR_NULL(reg)) {
+ /* Regulator may not be required for device */
+ if (reg)
+ dev_err(dev, "%s: Invalid regulator (%ld)\n", __func__,
+ PTR_ERR(reg));
+ rcu_read_unlock();
+ return 0;
+ }
+
+ list_for_each_entry_rcu(opp, &dev_opp->opp_list, node) {
+ if (!opp->available)
+ continue;
+
+ if (opp->u_volt_min < min_uV)
+ min_uV =3D opp->u_volt_min;
+ if (opp->u_volt_max > max_uV)
+ max_uV =3D opp->u_volt_max;
+ }
+
+ rcu_read_unlock();
+
+ /*
+ * The caller needs to ensure that dev_opp (and hence the regulator)
+ * isn't freed, while we are executing this routine.
+ */
+ ret =3D regulator_set_voltage_time(reg, min_uV, max_uV);
+ if (ret > 0)
+ latency_ns =3D ret * 1000;
+
+ return latency_ns;
+}
+EXPORT_SYMBOL_GPL(dev_pm_opp_get_max_volt_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 c70a18ac9c8a7..5daa43058ac10 100644
--- a/include/linux/pm_opp.h
+++ b/include/linux/pm_opp.h
@@ -34,6 +34,7 @@ bool dev_pm_opp_is_turbo(struct dev_pm_opp *opp);
=20
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);
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,
@@ -88,6 +89,11 @@ static inline unsigned long dev_pm_opp_get_max_clock_l=
atency(struct device *dev)
return 0;
}
=20
+static inline unsigned long dev_pm_opp_get_max_volt_latency(struct devic=
e *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