PM: domains: Introduce dev_pm_domain_set_performance_state()

The generic PM domain is currently the only PM domain variant that supports
performance scaling. To allow performance scaling to be supported through a
common interface, let's add an optional callback ->set_performance_state(),
in the struct dev_pm_domain.

Moreover, let's add a function, dev_pm_domain_set_performance_state(), that
may be called by consumers to request a new performance state for a device
through its PM domain.

Note that, in most cases it's preferred that a consumer use the OPP library
to request a new performance state for its device. Although, this requires
some additional changes to be supported, which are being implemented from
subsequent changes.

Signed-off-by: Ulf Hansson <ulf.hansson@linaro.org>
Acked-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Signed-off-by: Viresh Kumar <viresh.kumar@linaro.org>

1 files changed, 21 insertions, 0 deletions

diff --git a/drivers/base/power/common.c b/drivers/base/power/common.c
index 72115917e0bd..44ec20918a4d 100644
--- a/drivers/base/power/common.c
+++ b/drivers/base/power/common.c
@@ -228,3 +228,24 @@ void dev_pm_domain_set(struct device *dev, struct dev_pm_domain *pd)
 	device_pm_check_callbacks(dev);
 }
 EXPORT_SYMBOL_GPL(dev_pm_domain_set);
+
+/**
+ * dev_pm_domain_set_performance_state - Request a new performance state.
+ * @dev: The device to make the request for.
+ * @state: Target performance state for the device.
+ *
+ * This function should be called when a new performance state needs to be
+ * requested for a device that is attached to a PM domain. Note that, the
+ * support for performance scaling for PM domains is optional.
+ *
+ * Returns 0 on success and when performance scaling isn't supported, negative
+ * error code on failure.
+ */
+int dev_pm_domain_set_performance_state(struct device *dev, unsigned int state)
+{
+	if (dev->pm_domain && dev->pm_domain->set_performance_state)
+		return dev->pm_domain->set_performance_state(dev, state);
+
+	return 0;
+}
+EXPORT_SYMBOL_GPL(dev_pm_domain_set_performance_state);