PM/devfreq: Do not switch governors from sysfs when device is suspended

There is a possibility to switch the governors from sysfs even when the
device is in suspended state. This can cause a NOC error at times when
trying to access the device's monitor registers in a suspended state. This
change fixes this issue. Introduce a variable dev_suspended to know if
the device is in suspended state or not. Check if the device is suspended
before switching the governor from sysfs.

Change-Id: I15055aa51daa35272be4667e5bafb8ccd7933098
Signed-off-by: Rama Aparna Mallavarapu <aparnam@codeaurora.org>

drivers/devfreq/devfreq.c

@@ -585,6 +585,7 @@ struct devfreq *devfreq_add_device(struct device *dev,
 	devfreq->last_status.current_frequency = profile->initial_freq;
 	devfreq->data = data;
 	devfreq->nb.notifier_call = devfreq_notifier_call;
+	devfreq->dev_suspended = false;
 
 	if (!devfreq->profile->max_state && !devfreq->profile->freq_table) {
 		mutex_unlock(&devfreq->lock);
@@ -789,12 +790,16 @@ int devfreq_suspend_device(struct devfreq *devfreq)
 	if (!devfreq)
 		return -EINVAL;
 
-	if (!devfreq->governor)
+	mutex_lock(&devfreq->event_lock);
+	if (!devfreq->governor || devfreq->dev_suspended) {
+		mutex_unlock(&devfreq->event_lock);
 		return 0;
+	}
 
-	mutex_lock(&devfreq->event_lock);
 	ret = devfreq->governor->event_handler(devfreq,
 				DEVFREQ_GOV_SUSPEND, NULL);
+	if (!ret)
+		devfreq->dev_suspended = true;
 	mutex_unlock(&devfreq->event_lock);
 	return ret;
 }
@@ -815,12 +820,16 @@ int devfreq_resume_device(struct devfreq *devfreq)
 	if (!devfreq)
 		return -EINVAL;
 
-	if (!devfreq->governor)
+	mutex_lock(&devfreq->event_lock);
+	if (!devfreq->governor) {
+		mutex_unlock(&devfreq->event_lock);
 		return 0;
+	}
 
-	mutex_lock(&devfreq->event_lock);
 	ret = devfreq->governor->event_handler(devfreq,
 				DEVFREQ_GOV_RESUME, NULL);
+	if (!ret)
+		devfreq->dev_suspended = false;
 	mutex_unlock(&devfreq->event_lock);
 	return ret;
 }
@@ -983,6 +992,10 @@ static ssize_t governor_store(struct device *dev, struct device_attribute *attr,
 	}
 
 	mutex_lock(&df->event_lock);
+	if (df->dev_suspended) {
+		ret = -EINVAL;
+		goto gov_stop_out;
+	}
 	if (df->governor) {
 		ret = df->governor->event_handler(df, DEVFREQ_GOV_STOP, NULL);
 		if (ret) {

include/linux/devfreq.h

@@ -191,6 +191,7 @@ struct devfreq {
 	unsigned long last_stat_updated;
 
 	struct srcu_notifier_head transition_notifier_list;
+	bool dev_suspended;
 };
 
 struct devfreq_freqs {