1 files changed, 23 insertions, 1 deletions

diff --git a/kernel/include/linux/devfreq.h b/kernel/include/linux/devfreq.h
index ce447f0f1..68030e22a 100644
--- a/kernel/include/linux/devfreq.h
+++ b/kernel/include/linux/devfreq.h
@@ -65,7 +65,10 @@ struct devfreq_dev_status {
  *			The "flags" parameter's possible values are
  *			explained above with "DEVFREQ_FLAG_*" macros.
  * @get_dev_status:	The device should provide the current performance
- *			status to devfreq, which is used by governors.
+ *			status to devfreq. Governors are recommended not to
+ *			use this directly. Instead, governors are recommended
+ *			to use devfreq_update_stats() along with
+ *			devfreq.last_status.
  * @get_cur_freq:	The device should provide the current frequency
  *			at which it is operating.
  * @exit:		An optional callback that is called when devfreq
@@ -161,6 +164,7 @@ struct devfreq {
 	struct delayed_work work;
 
 	unsigned long previous_freq;
+	struct devfreq_dev_status last_status;
 
 	void *data; /* private data for governors */
 
@@ -204,6 +208,19 @@ extern int devm_devfreq_register_opp_notifier(struct device *dev,
 extern void devm_devfreq_unregister_opp_notifier(struct device *dev,
 						struct devfreq *devfreq);
 
+/**
+ * devfreq_update_stats() - update the last_status pointer in struct devfreq
+ * @df:		the devfreq instance whose status needs updating
+ *
+ *  Governors are recommended to use this function along with last_status,
+ * which allows other entities to reuse the last_status without affecting
+ * the values fetched later by governors.
+ */
+static inline int devfreq_update_stats(struct devfreq *df)
+{
+	return df->profile->get_dev_status(df->dev.parent, &df->last_status);
+}
+
 #if IS_ENABLED(CONFIG_DEVFREQ_GOV_SIMPLE_ONDEMAND)
 /**
  * struct devfreq_simple_ondemand_data - void *data fed to struct devfreq
@@ -289,6 +306,11 @@ static inline void devm_devfreq_unregister_opp_notifier(struct device *dev,
 							struct devfreq *devfreq)
 {
 }
+
+static inline int devfreq_update_stats(struct devfreq *df)
+{
+	return -EINVAL;
+}
 #endif /* CONFIG_PM_DEVFREQ */
 
 #endif /* __LINUX_DEVFREQ_H__ */