8 files changed, 278 insertions, 296 deletions

diff --git a/Documentation/ABI/testing/sysfs-class-devfreq b/Documentation/ABI/testing/sysfs-class-devfreq
index 23d78b5aab11..89283b1b0240 100644
--- a/Documentation/ABI/testing/sysfs-class-devfreq
+++ b/Documentation/ABI/testing/sysfs-class-devfreq
@@ -21,14 +21,6 @@ Description:
                 The /sys/class/devfreq/.../cur_freq shows the current
                 frequency of the corresponding devfreq object.
 
-What:           /sys/class/devfreq/.../central_polling
-Date:           September 2011
-Contact:        MyungJoo Ham <myungjoo.ham@samsung.com>
-Description:
-                The /sys/class/devfreq/.../central_polling shows whether
-                the devfreq ojbect is using devfreq-provided central
-                polling mechanism or not.
-
 What:           /sys/class/devfreq/.../polling_interval
 Date:           September 2011
 Contact:        MyungJoo Ham <myungjoo.ham@samsung.com>
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));