This patch adds implementation for global suspend/resume for
devfreq framework. System suspend will next use these functions.
The patch draws on Tobias Jakobi's work posted ~2 years ago, who tried to
solve issue with devfreq device's frequency during suspend/resume.
During the discussion on LKML some corner cases and comments appeared
related to the design. This patch address them keeping in mind suggestions
from Chanwoo Choi.
Suggested-by: Tobias Jakobi <tjakobi@xxxxxxxxxxxxxxxxxxxxx>
Suggested-by: Chanwoo Choi <cw00.choi@xxxxxxxxxxx>
Signed-off-by: Lukasz Luba <l.luba@xxxxxxxxxxxxxxxxxxx>
---
drivers/devfreq/devfreq.c | 49 +++++++++++++++++++++++++++++++++++++++++++++++
include/linux/devfreq.h | 7 +++++++
2 files changed, 56 insertions(+)
diff --git a/drivers/devfreq/devfreq.c b/drivers/devfreq/devfreq.c
index 7e09de8..2f4391c 100644
--- a/drivers/devfreq/devfreq.c
+++ b/drivers/devfreq/devfreq.c
@@ -44,6 +44,9 @@ static LIST_HEAD(devfreq_governor_list);
static LIST_HEAD(devfreq_list);
static DEFINE_MUTEX(devfreq_list_lock);
+/* Flag showing state of suspend/resume */
+static bool devfreq_suspended;
+
/**
* find_device_devfreq() - find devfreq struct using device pointer
* @dev: device pointer used to lookup device devfreq.
@@ -938,6 +941,52 @@ int devfreq_resume_device(struct devfreq *devfreq)
EXPORT_SYMBOL(devfreq_resume_device);
/**
+ * devfreq_suspend() - Suspend devfreq governors and devices
+ *
+ * Called during system wide Suspend/Hibernate cycles for suspending governors
+ * and devices preserving the state for resume. On some platforms the devfreq
+ * device must have precise state (frequency) after resume in order to provide
+ * fully operating setup.
+ */
+void devfreq_suspend(void)
+{
+ struct devfreq *devfreq;
+ int ret;
+
+ mutex_lock(&devfreq_list_lock);
+ list_for_each_entry(devfreq, &devfreq_list, node) {
+ ret = devfreq_suspend_device(devfreq);
+ if (ret)
+ dev_warn(&devfreq->dev, "device suspend failed\n");
+ }
+ mutex_unlock(&devfreq_list_lock);
+
+ devfreq_suspended = true;
+}
+
+/**
+ * devfreq_resume() - Resume devfreq governors and devices
+ *
+ * Called during system wide Suspend/Hibernate cycle for resuming governors and
+ * devices that are suspended with devfreq_suspend().
+ */
+void devfreq_resume(void)
+{
+ struct devfreq *devfreq;
+ int ret;
+
+ devfreq_suspended = false;
+
+ mutex_lock(&devfreq_list_lock);
+ list_for_each_entry(devfreq, &devfreq_list, node) {
+ ret = devfreq_resume_device(devfreq);
+ if (ret)
+ dev_warn(&devfreq->dev, "device resume failed\n");
+ }
+ mutex_unlock(&devfreq_list_lock);
+}
+
+/**
* devfreq_add_governor() - Add devfreq governor
* @governor: the devfreq governor to be added
*/
diff --git a/include/linux/devfreq.h b/include/linux/devfreq.h
index 7fe96f9..4f0fea8 100644
--- a/include/linux/devfreq.h
+++ b/include/linux/devfreq.h
@@ -202,6 +202,10 @@ extern void devm_devfreq_remove_device(struct device *dev,
extern int devfreq_suspend_device(struct devfreq *devfreq);
extern int devfreq_resume_device(struct devfreq *devfreq);
+
+extern void devfreq_suspend(void);
+extern void devfreq_resume(void);
+
/**
* update_devfreq() - Reevaluate the device and configure frequency
* @devfreq: the devfreq device
@@ -396,6 +400,9 @@ static inline int devfreq_update_stats(struct devfreq *df)
{
return -EINVAL;
}
+
+static inline void devfreq_suspend(void) {}
+static inline void devfreq_resume(void) {}
#endif /* CONFIG_PM_DEVFREQ */
#endif /* __LINUX_DEVFREQ_H__ */
--
2.7.4
