6 files changed, 268 insertions, 264 deletions

diff --git a/drivers/devfreq/devfreq.c b/drivers/devfreq/devfreq.c
index b146d76f04cf..1aaf1aeb1f1d 100644
--- a/drivers/devfreq/devfreq.c
+++ b/drivers/devfreq/devfreq.c
@@ -30,17 +30,11 @@
 struct class *devfreq_class;
 
 /*
- * devfreq_work periodically monitors every registered device.
- * The minimum polling interval is one jiffy. The polling interval is
- * determined by the minimum polling period among all polling devfreq
- * devices. The resolution of polling interval is one jiffy.
+ * devfreq core provides delayed work based load monitoring helper
+ * functions. Governors can use these or can implement their own
+ * monitoring mechanism.
  */
-static bool polling;
 static struct workqueue_struct *devfreq_wq;
-static struct delayed_work devfreq_work;
-
-/* wait removing if this is to be removed */
-static struct devfreq *wait_remove_device;
 
 /* The list of all device-devfreq */
 static LIST_HEAD(devfreq_list);
@@ -72,6 +66,8 @@ static struct devfreq *find_device_devfreq(struct device *dev)
         return ERR_PTR(-ENODEV);
 }
 
+/* Load monitoring helper functions for governors use */
+
 /**
  * update_devfreq() - Reevaluate the device and configure frequency.
  * @devfreq:    the devfreq instance.
@@ -121,6 +117,152 @@ int update_devfreq(struct devfreq *devfreq)
 }
 
 /**
+ * devfreq_monitor() - Periodically poll devfreq objects.
+ * @work:       the work struct used to run devfreq_monitor periodically.
+ *
+ */
+static void devfreq_monitor(struct work_struct *work)
+{
+        int err;
+        struct devfreq *devfreq = container_of(work,
+                                        struct devfreq, work.work);
+
+        mutex_lock(&devfreq->lock);
+        err = update_devfreq(devfreq);
+        if (err)
+                dev_err(&devfreq->dev, "dvfs failed with (%d) error\n", err);
+
+        queue_delayed_work(devfreq_wq, &devfreq->work,
+                                msecs_to_jiffies(devfreq->profile->polling_ms));
+        mutex_unlock(&devfreq->lock);
+}
+
+/**
+ * devfreq_monitor_start() - Start load monitoring of devfreq instance
+ * @devfreq:    the devfreq instance.
+ *
+ * Helper function for starting devfreq device load monitoing. By
+ * default delayed work based monitoring is supported. Function
+ * to be called from governor in response to DEVFREQ_GOV_START
+ * event when device is added to devfreq framework.
+ */
+void devfreq_monitor_start(struct devfreq *devfreq)
+{
+        INIT_DEFERRABLE_WORK(&devfreq->work, devfreq_monitor);
+        if (devfreq->profile->polling_ms)
+                queue_delayed_work(devfreq_wq, &devfreq->work,
+                        msecs_to_jiffies(devfreq->profile->polling_ms));
+}
+
+/**
+ * devfreq_monitor_stop() - Stop load monitoring of a devfreq instance
+ * @devfreq:    the devfreq instance.
+ *
+ * Helper function to stop devfreq device load monitoing. Function
+ * to be called from governor in response to DEVFREQ_GOV_STOP
+ * event when device is removed from devfreq framework.
+ */
+void devfreq_monitor_stop(struct devfreq *devfreq)
+{
+        cancel_delayed_work_sync(&devfreq->work);
+}
+
+/**
+ * devfreq_monitor_suspend() - Suspend load monitoring of a devfreq instance
+ * @devfreq:    the devfreq instance.
+ *
+ * Helper function to suspend devfreq device load monitoing. Function
+ * to be called from governor in response to DEVFREQ_GOV_SUSPEND
+ * event or when polling interval is set to zero.
+ *
+ * Note: Though this function is same as devfreq_monitor_stop(),
+ * intentionally kept separate to provide hooks for collecting
+ * transition statistics.
+ */
+void devfreq_monitor_suspend(struct devfreq *devfreq)
+{
+        mutex_lock(&devfreq->lock);
+        if (devfreq->stop_polling) {
+                mutex_unlock(&devfreq->lock);
+                return;
+        }
+
+        devfreq->stop_polling = true;
+        mutex_unlock(&devfreq->lock);
+        cancel_delayed_work_sync(&devfreq->work);
+}
+
+/**
+ * devfreq_monitor_resume() - Resume load monitoring of a devfreq instance
+ * @devfreq:    the devfreq instance.
+ *
+ * Helper function to resume devfreq device load monitoing. Function
+ * to be called from governor in response to DEVFREQ_GOV_RESUME
+ * event or when polling interval is set to non-zero.
+ */
+void devfreq_monitor_resume(struct devfreq *devfreq)
+{
+        mutex_lock(&devfreq->lock);
+        if (!devfreq->stop_polling)
+                goto out;
+
+        if (!delayed_work_pending(&devfreq->work) &&
+                        devfreq->profile->polling_ms)
+                queue_delayed_work(devfreq_wq, &devfreq->work,
+                        msecs_to_jiffies(devfreq->profile->polling_ms));
+        devfreq->stop_polling = false;
+
+out:
+        mutex_unlock(&devfreq->lock);
+}
+
+/**
+ * devfreq_interval_update() - Update device devfreq monitoring interval
+ * @devfreq:    the devfreq instance.
+ * @delay:      new polling interval to be set.
+ *
+ * Helper function to set new load monitoring polling interval. Function
+ * to be called from governor in response to DEVFREQ_GOV_INTERVAL event.
+ */
+void devfreq_interval_update(struct devfreq *devfreq, unsigned int *delay)
+{
+        unsigned int cur_delay = devfreq->profile->polling_ms;
+        unsigned int new_delay = *delay;
+
+        mutex_lock(&devfreq->lock);
+        devfreq->profile->polling_ms = new_delay;
+
+        if (devfreq->stop_polling)
+                goto out;
+
+        /* if new delay is zero, stop polling */
+        if (!new_delay) {
+                mutex_unlock(&devfreq->lock);
+                cancel_delayed_work_sync(&devfreq->work);
+                return;
+        }
+
+        /* if current delay is zero, start polling with new delay */
+        if (!cur_delay) {
+                queue_delayed_work(devfreq_wq, &devfreq->work,
+                        msecs_to_jiffies(devfreq->profile->polling_ms));
+                goto out;
+        }
+
+        /* if current delay is greater than new delay, restart polling */
+        if (cur_delay > new_delay) {
+                mutex_unlock(&devfreq->lock);
+                cancel_delayed_work_sync(&devfreq->work);
+                mutex_lock(&devfreq->lock);
+                if (!devfreq->stop_polling)
+                        queue_delayed_work(devfreq_wq, &devfreq->work,
+                              msecs_to_jiffies(devfreq->profile->polling_ms));
+        }
+out:
+        mutex_unlock(&devfreq->lock);
+}
+
+/**
  * devfreq_notifier_call() - Notify that the device frequency requirements
  *                         has been changed out of devfreq framework.
  * @nb          the notifier_block (supposed to be devfreq->nb)
@@ -143,59 +285,32 @@ static int devfreq_notifier_call(struct notifier_block *nb, unsigned long type,
 }
 
 /**
- * _remove_devfreq() - Remove devfreq from the device.
+ * _remove_devfreq() - Remove devfreq from the list and release its resources.
  * @devfreq:    the devfreq struct
  * @skip:       skip calling device_unregister().
- *
- * Note that the caller should lock devfreq->lock before calling
- * this. _remove_devfreq() will unlock it and free devfreq
- * internally. devfreq_list_lock should be locked by the caller
- * as well (not relased at return)
- *
- * Lock usage:
- * devfreq->lock: locked before call.
- *                unlocked at return (and freed)
- * devfreq_list_lock: locked before call.
- *                    kept locked at return.
- *                    if devfreq is centrally polled.
- *
- * Freed memory:
- * devfreq
  */
 static void _remove_devfreq(struct devfreq *devfreq, bool skip)
 {
-        if (!mutex_is_locked(&devfreq->lock)) {
-                WARN(true, "devfreq->lock must be locked by the caller.\n");
-                return;
-        }
-        if (!devfreq->governor->no_central_polling &&
-            !mutex_is_locked(&devfreq_list_lock)) {
-                WARN(true, "devfreq_list_lock must be locked by the caller.\n");
+        mutex_lock(&devfreq_list_lock);
+        if (IS_ERR(find_device_devfreq(devfreq->dev.parent))) {
+                mutex_unlock(&devfreq_list_lock);
+                dev_warn(&devfreq->dev, "releasing devfreq which doesn't exist\n");
                 return;
         }
+        list_del(&devfreq->node);
+        mutex_unlock(&devfreq_list_lock);
 
-        if (devfreq->being_removed)
-                return;
-
-        devfreq->being_removed = true;
+        devfreq->governor->event_handler(devfreq, DEVFREQ_GOV_STOP, NULL);
 
         if (devfreq->profile->exit)
                 devfreq->profile->exit(devfreq->dev.parent);
 
-        if (devfreq->governor->exit)
-                devfreq->governor->exit(devfreq);
-
         if (!skip && get_device(&devfreq->dev)) {
                 device_unregister(&devfreq->dev);
                 put_device(&devfreq->dev);
         }
 
-        if (!devfreq->governor->no_central_polling)
-                list_del(&devfreq->node);
-
-        mutex_unlock(&devfreq->lock);
         mutex_destroy(&devfreq->lock);
-
         kfree(devfreq);
 }
 
@@ -210,130 +325,8 @@ static void _remove_devfreq(struct devfreq *devfreq, bool skip)
 static void devfreq_dev_release(struct device *dev)
 {
         struct devfreq *devfreq = to_devfreq(dev);
-        bool central_polling = !devfreq->governor->no_central_polling;
-
-        /*
-         * If devfreq_dev_release() was called by device_unregister() of
-         * _remove_devfreq(), we cannot mutex_lock(&devfreq->lock) and
-         * being_removed is already set. This also partially checks the case
-         * where devfreq_dev_release() is called from a thread other than
-         * the one called _remove_devfreq(); however, this case is
-         * dealt completely with another following being_removed check.
-         *
-         * Because being_removed is never being
-         * unset, we do not need to worry about race conditions on
-         * being_removed.
-         */
-        if (devfreq->being_removed)
-                return;
 
-        if (central_polling)
-                mutex_lock(&devfreq_list_lock);
-
-        mutex_lock(&devfreq->lock);
-
-        /*
-         * Check being_removed flag again for the case where
-         * devfreq_dev_release() was called in a thread other than the one
-         * possibly called _remove_devfreq().
-         */
-        if (devfreq->being_removed) {
-                mutex_unlock(&devfreq->lock);
-                goto out;
-        }
-
-        /* devfreq->lock is unlocked and removed in _removed_devfreq() */
         _remove_devfreq(devfreq, true);
-
-out:
-        if (central_polling)
-                mutex_unlock(&devfreq_list_lock);
-}
-
-/**
- * devfreq_monitor() - Periodically poll devfreq objects.
- * @work: the work struct used to run devfreq_monitor periodically.
- *
- */
-static void devfreq_monitor(struct work_struct *work)
-{
-        static unsigned long last_polled_at;
-        struct devfreq *devfreq, *tmp;
-        int error;
-        unsigned long jiffies_passed;
-        unsigned long next_jiffies = ULONG_MAX, now = jiffies;
-        struct device *dev;
-
-        /* Initially last_polled_at = 0, polling every device at bootup */
-        jiffies_passed = now - last_polled_at;
-        last_polled_at = now;
-        if (jiffies_passed == 0)
-                jiffies_passed = 1;
-
-        mutex_lock(&devfreq_list_lock);
-        list_for_each_entry_safe(devfreq, tmp, &devfreq_list, node) {
-                mutex_lock(&devfreq->lock);
-                dev = devfreq->dev.parent;
-
-                /* Do not remove tmp for a while */
-                wait_remove_device = tmp;
-
-                if (devfreq->governor->no_central_polling ||
-                    devfreq->next_polling == 0) {
-                        mutex_unlock(&devfreq->lock);
-                        continue;
-                }
-                mutex_unlock(&devfreq_list_lock);
-
-                /*
-                 * Reduce more next_polling if devfreq_wq took an extra
-                 * delay. (i.e., CPU has been idled.)
-                 */
-                if (devfreq->next_polling <= jiffies_passed) {
-                        error = update_devfreq(devfreq);
-
-                        /* Remove a devfreq with an error. */
-                        if (error && error != -EAGAIN) {
-
-                                dev_err(dev, "Due to update_devfreq error(%d), devfreq(%s) is removed from the device\n",
-                                        error, devfreq->governor->name);
-
-                                /*
-                                 * Unlock devfreq before locking the list
-                                 * in order to avoid deadlock with
-                                 * find_device_devfreq or others
-                                 */
-                                mutex_unlock(&devfreq->lock);
-                                mutex_lock(&devfreq_list_lock);
-                                /* Check if devfreq is already removed */
-                                if (IS_ERR(find_device_devfreq(dev)))
-                                        continue;
-                                mutex_lock(&devfreq->lock);
-                                /* This unlocks devfreq->lock and free it */
-                                _remove_devfreq(devfreq, false);
-                                continue;
-                        }
-                        devfreq->next_polling = devfreq->polling_jiffies;
-                } else {
-                        devfreq->next_polling -= jiffies_passed;
-                }
-
-                if (devfreq->next_polling)
-                        next_jiffies = (next_jiffies > devfreq->next_polling) ?
-                                        devfreq->next_polling : next_jiffies;
-
-                mutex_unlock(&devfreq->lock);
-                mutex_lock(&devfreq_list_lock);
-        }
-        wait_remove_device = NULL;
-        mutex_unlock(&devfreq_list_lock);
-
-        if (next_jiffies > 0 && next_jiffies < ULONG_MAX) {
-                polling = true;
-                queue_delayed_work(devfreq_wq, &devfreq_work, next_jiffies);
-        } else {
-                polling = false;
-        }
 }
 
 /**
@@ -357,16 +350,13 @@ struct devfreq *devfreq_add_device(struct device *dev,
                 return ERR_PTR(-EINVAL);
         }
 
-
-        if (!governor->no_central_polling) {
-                mutex_lock(&devfreq_list_lock);
-                devfreq = find_device_devfreq(dev);
-                mutex_unlock(&devfreq_list_lock);
-                if (!IS_ERR(devfreq)) {
-                        dev_err(dev, "%s: Unable to create devfreq for the device. It already has one.\n", __func__);
-                        err = -EINVAL;
-                        goto err_out;
-                }
+        mutex_lock(&devfreq_list_lock);
+        devfreq = find_device_devfreq(dev);
+        mutex_unlock(&devfreq_list_lock);
+        if (!IS_ERR(devfreq)) {
+                dev_err(dev, "%s: Unable to create devfreq for the device. It already has one.\n", __func__);
+                err = -EINVAL;
+                goto err_out;
         }
 
         devfreq = kzalloc(sizeof(struct devfreq), GFP_KERNEL);
@@ -386,48 +376,41 @@ struct devfreq *devfreq_add_device(struct device *dev,
         devfreq->governor = governor;
         devfreq->previous_freq = profile->initial_freq;
         devfreq->data = data;
-        devfreq->next_polling = devfreq->polling_jiffies
-                              = msecs_to_jiffies(devfreq->profile->polling_ms);
         devfreq->nb.notifier_call = devfreq_notifier_call;
 
         dev_set_name(&devfreq->dev, dev_name(dev));
         err = device_register(&devfreq->dev);
         if (err) {
                 put_device(&devfreq->dev);
+                mutex_unlock(&devfreq->lock);
                 goto err_dev;
         }
 
-        if (governor->init)
-                err = governor->init(devfreq);
-        if (err)
-                goto err_init;
-
         mutex_unlock(&devfreq->lock);
 
-        if (governor->no_central_polling)
-                goto out;
-
         mutex_lock(&devfreq_list_lock);
-
         list_add(&devfreq->node, &devfreq_list);
+        mutex_unlock(&devfreq_list_lock);
 
-        if (devfreq_wq && devfreq->next_polling && !polling) {
-                polling = true;
-                queue_delayed_work(devfreq_wq, &devfreq_work,
-                                   devfreq->next_polling);
+        err = devfreq->governor->event_handler(devfreq,
+                                DEVFREQ_GOV_START, NULL);
+        if (err) {
+                dev_err(dev, "%s: Unable to start governor for the device\n",
+                        __func__);
+                goto err_init;
         }
-        mutex_unlock(&devfreq_list_lock);
-out:
+
         return devfreq;
 
 err_init:
+        list_del(&devfreq->node);
         device_unregister(&devfreq->dev);
 err_dev:
-        mutex_unlock(&devfreq->lock);
         kfree(devfreq);
 err_out:
         return ERR_PTR(err);
 }
+EXPORT_SYMBOL(devfreq_add_device);
 
 /**
  * devfreq_remove_device() - Remove devfreq feature from a device.
@@ -435,30 +418,14 @@ err_out:
  */
 int devfreq_remove_device(struct devfreq *devfreq)
 {
-        bool central_polling;
-
         if (!devfreq)
                 return -EINVAL;
 
-        central_polling = !devfreq->governor->no_central_polling;
-
-        if (central_polling) {
-                mutex_lock(&devfreq_list_lock);
-                while (wait_remove_device == devfreq) {
-                        mutex_unlock(&devfreq_list_lock);
-                        schedule();
-                        mutex_lock(&devfreq_list_lock);
-                }
-        }
-
-        mutex_lock(&devfreq->lock);
-        _remove_devfreq(devfreq, false); /* it unlocks devfreq->lock */
-
-        if (central_polling)
-                mutex_unlock(&devfreq_list_lock);
+        _remove_devfreq(devfreq, false);
 
         return 0;
 }
+EXPORT_SYMBOL(devfreq_remove_device);
 
 static ssize_t show_governor(struct device *dev,
                              struct device_attribute *attr, char *buf)
@@ -490,35 +457,13 @@ static ssize_t store_polling_interval(struct device *dev,
         if (ret != 1)
                 goto out;
 
-        mutex_lock(&df->lock);
-        df->profile->polling_ms = value;
-        df->next_polling = df->polling_jiffies
-                         = msecs_to_jiffies(value);
-        mutex_unlock(&df->lock);
-
+        df->governor->event_handler(df, DEVFREQ_GOV_INTERVAL, &value);
         ret = count;
 
-        if (df->governor->no_central_polling)
-                goto out;
-
-        mutex_lock(&devfreq_list_lock);
-        if (df->next_polling > 0 && !polling) {
-                polling = true;
-                queue_delayed_work(devfreq_wq, &devfreq_work,
-                                   df->next_polling);
-        }
-        mutex_unlock(&devfreq_list_lock);
 out:
         return ret;
 }
 
-static ssize_t show_central_polling(struct device *dev,
-                                    struct device_attribute *attr, char *buf)
-{
-        return sprintf(buf, "%d\n",
-                       !to_devfreq(dev)->governor->no_central_polling);
-}
-
 static ssize_t store_min_freq(struct device *dev, struct device_attribute *attr,
                               const char *buf, size_t count)
 {
@@ -590,7 +535,6 @@ static ssize_t show_max_freq(struct device *dev, struct device_attribute *attr,
 static struct device_attribute devfreq_attrs[] = {
         __ATTR(governor, S_IRUGO, show_governor, NULL),
         __ATTR(cur_freq, S_IRUGO, show_freq, NULL),
-        __ATTR(central_polling, S_IRUGO, show_central_polling, NULL),
         __ATTR(polling_interval, S_IRUGO | S_IWUSR, show_polling_interval,
                store_polling_interval),
         __ATTR(min_freq, S_IRUGO | S_IWUSR, show_min_freq, store_min_freq),
@@ -598,23 +542,6 @@ static struct device_attribute devfreq_attrs[] = {
         { },
 };
 
-/**
- * devfreq_start_polling() - Initialize data structure for devfreq framework and
- *                         start polling registered devfreq devices.
- */
-static int __init devfreq_start_polling(void)
-{
-        mutex_lock(&devfreq_list_lock);
-        polling = false;
-        devfreq_wq = create_freezable_workqueue("devfreq_wq");
-        INIT_DEFERRABLE_WORK(&devfreq_work, devfreq_monitor);
-        mutex_unlock(&devfreq_list_lock);
-
-        devfreq_monitor(&devfreq_work.work);
-        return 0;
-}
-late_initcall(devfreq_start_polling);
-
 static int __init devfreq_init(void)
 {
         devfreq_class = class_create(THIS_MODULE, "devfreq");
@@ -622,7 +549,15 @@ static int __init devfreq_init(void)
                 pr_err("%s: couldn't create class\n", __FILE__);
                 return PTR_ERR(devfreq_class);
         }
+
+        devfreq_wq = create_freezable_workqueue("devfreq_wq");
+        if (IS_ERR(devfreq_wq)) {
+                class_destroy(devfreq_class);
+                pr_err("%s: couldn't create workqueue\n", __FILE__);
+                return PTR_ERR(devfreq_wq);
+        }
         devfreq_class->dev_attrs = devfreq_attrs;
+
         return 0;
 }
 subsys_initcall(devfreq_init);
@@ -630,6 +565,7 @@ subsys_initcall(devfreq_init);
 static void __exit devfreq_exit(void)
 {
         class_destroy(devfreq_class);
+        destroy_workqueue(devfreq_wq);
 }
 module_exit(devfreq_exit);
 
diff --git a/drivers/devfreq/governor.h b/drivers/devfreq/governor.h
index ea7f13c58ded..bb3aff32d627 100644
--- a/drivers/devfreq/governor.h
+++ b/drivers/devfreq/governor.h
@@ -18,7 +18,18 @@
 
 #define to_devfreq(DEV) container_of((DEV), struct devfreq, dev)
 
+/* Devfreq events */
+#define DEVFREQ_GOV_START                       0x1
+#define DEVFREQ_GOV_STOP                        0x2
+#define DEVFREQ_GOV_INTERVAL                    0x3
+
 /* Caution: devfreq->lock must be locked before calling update_devfreq */
 extern int update_devfreq(struct devfreq *devfreq);
 
+extern void devfreq_monitor_start(struct devfreq *devfreq);
+extern void devfreq_monitor_stop(struct devfreq *devfreq);
+extern void devfreq_monitor_suspend(struct devfreq *devfreq);
+extern void devfreq_monitor_resume(struct devfreq *devfreq);
+extern void devfreq_interval_update(struct devfreq *devfreq,
+                                        unsigned int *delay);
 #endif /* _GOVERNOR_H */
diff --git a/drivers/devfreq/governor_performance.c b/drivers/devfreq/governor_performance.c
index af75ddd4f158..eea3f9bd7894 100644
--- a/drivers/devfreq/governor_performance.c
+++ b/drivers/devfreq/governor_performance.c
@@ -26,14 +26,22 @@ static int devfreq_performance_func(struct devfreq *df,
         return 0;
 }
 
-static int performance_init(struct devfreq *devfreq)
+static int devfreq_performance_handler(struct devfreq *devfreq,
+                                unsigned int event, void *data)
 {
-        return update_devfreq(devfreq);
+        int ret = 0;
+
+        if (event == DEVFREQ_GOV_START) {
+                mutex_lock(&devfreq->lock);
+                ret = update_devfreq(devfreq);
+                mutex_unlock(&devfreq->lock);
+        }
+
+        return ret;
 }
 
 const struct devfreq_governor devfreq_performance = {
         .name = "performance",
-        .init = performance_init,
         .get_target_freq = devfreq_performance_func,
-        .no_central_polling = true,
+        .event_handler = devfreq_performance_handler,
 };
diff --git a/drivers/devfreq/governor_powersave.c b/drivers/devfreq/governor_powersave.c
index fec0cdbd2477..2868d98ed3e2 100644
--- a/drivers/devfreq/governor_powersave.c
+++ b/drivers/devfreq/governor_powersave.c
@@ -23,14 +23,22 @@ static int devfreq_powersave_func(struct devfreq *df,
         return 0;
 }
 
-static int powersave_init(struct devfreq *devfreq)
+static int devfreq_powersave_handler(struct devfreq *devfreq,
+                                unsigned int event, void *data)
 {
-        return update_devfreq(devfreq);
+        int ret = 0;
+
+        if (event == DEVFREQ_GOV_START) {
+                mutex_lock(&devfreq->lock);
+                ret = update_devfreq(devfreq);
+                mutex_unlock(&devfreq->lock);
+        }
+
+        return ret;
 }
 
 const struct devfreq_governor devfreq_powersave = {
         .name = "powersave",
-        .init = powersave_init,
         .get_target_freq = devfreq_powersave_func,
-        .no_central_polling = true,
+        .event_handler = devfreq_powersave_handler,
 };
diff --git a/drivers/devfreq/governor_simpleondemand.c b/drivers/devfreq/governor_simpleondemand.c
index a2e3eae79011..3716a659122b 100644
--- a/drivers/devfreq/governor_simpleondemand.c
+++ b/drivers/devfreq/governor_simpleondemand.c
@@ -12,6 +12,7 @@
 #include <linux/errno.h>
 #include <linux/devfreq.h>
 #include <linux/math64.h>
+#include "governor.h"
 
 /* Default constants for DevFreq-Simple-Ondemand (DFSO) */
 #define DFSO_UPTHRESHOLD        (90)
@@ -88,7 +89,30 @@ static int devfreq_simple_ondemand_func(struct devfreq *df,
         return 0;
 }
 
+static int devfreq_simple_ondemand_handler(struct devfreq *devfreq,
+                                unsigned int event, void *data)
+{
+        switch (event) {
+        case DEVFREQ_GOV_START:
+                devfreq_monitor_start(devfreq);
+                break;
+
+        case DEVFREQ_GOV_STOP:
+                devfreq_monitor_stop(devfreq);
+                break;
+
+        case DEVFREQ_GOV_INTERVAL:
+                devfreq_interval_update(devfreq, (unsigned int *)data);
+                break;
+        default:
+                break;
+        }
+
+        return 0;
+}
+
 const struct devfreq_governor devfreq_simple_ondemand = {
         .name = "simple_ondemand",
         .get_target_freq = devfreq_simple_ondemand_func,
+        .event_handler = devfreq_simple_ondemand_handler,
 };
diff --git a/drivers/devfreq/governor_userspace.c b/drivers/devfreq/governor_userspace.c
index 0681246fc89d..7067555bd444 100644
--- a/drivers/devfreq/governor_userspace.c
+++ b/drivers/devfreq/governor_userspace.c
@@ -116,10 +116,27 @@ static void userspace_exit(struct devfreq *devfreq)
         devfreq->data = NULL;
 }
 
+static int devfreq_userspace_handler(struct devfreq *devfreq,
+                        unsigned int event, void *data)
+{
+        int ret = 0;
+
+        switch (event) {
+        case DEVFREQ_GOV_START:
+                ret = userspace_init(devfreq);
+                break;
+        case DEVFREQ_GOV_STOP:
+                userspace_exit(devfreq);
+                break;
+        default:
+                break;
+        }
+
+        return ret;
+}
+
 const struct devfreq_governor devfreq_userspace = {
         .name = "userspace",
         .get_target_freq = devfreq_userspace_func,
-        .init = userspace_init,
-        .exit = userspace_exit,
-        .no_central_polling = true,
+        .event_handler = devfreq_userspace_handler,
 };