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);
return ERR_PTR(-ENODEV);
}
+/* Load monitoring helper functions for governors use */
+
/**
* update_devfreq() - Reevaluate the device and configure frequency.
* @devfreq: the devfreq instance.
return err;
}
+/**
+ * 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.
}
/**
- * _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);
}
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;
- }
}
/**
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);
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.
*/
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)
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)
{
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),
{ },
};
-/**
- * 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");
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);
static void __exit devfreq_exit(void)
{
class_destroy(devfreq_class);
+ destroy_workqueue(devfreq_wq);
}
module_exit(devfreq_exit);
projects / users / jedix / linux-maple.git / commitdiff