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@@ -0,0 +1,601 @@
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+/*
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+ * devfreq: Generic Dynamic Voltage and Frequency Scaling (DVFS) Framework
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+ * for Non-CPU Devices.
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+ *
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+ * Copyright (C) 2011 Samsung Electronics
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+ * MyungJoo Ham <myungjoo.ham@samsung.com>
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+ *
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+ * This program is free software; you can redistribute it and/or modify
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+ * it under the terms of the GNU General Public License version 2 as
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+ * published by the Free Software Foundation.
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+ */
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+
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+#include <linux/kernel.h>
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+#include <linux/sched.h>
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+#include <linux/errno.h>
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+#include <linux/err.h>
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+#include <linux/init.h>
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+#include <linux/slab.h>
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+#include <linux/opp.h>
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+#include <linux/devfreq.h>
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+#include <linux/workqueue.h>
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+#include <linux/platform_device.h>
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+#include <linux/list.h>
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+#include <linux/printk.h>
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+#include <linux/hrtimer.h>
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+#include "governor.h"
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+
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+struct class *devfreq_class;
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+
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+/*
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+ * devfreq_work periodically monitors every registered device.
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+ * The minimum polling interval is one jiffy. The polling interval is
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+ * determined by the minimum polling period among all polling devfreq
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+ * devices. The resolution of polling interval is one jiffy.
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+ */
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+static bool polling;
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+static struct workqueue_struct *devfreq_wq;
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+static struct delayed_work devfreq_work;
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+
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+/* wait removing if this is to be removed */
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+static struct devfreq *wait_remove_device;
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+
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+/* The list of all device-devfreq */
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+static LIST_HEAD(devfreq_list);
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+static DEFINE_MUTEX(devfreq_list_lock);
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+
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+/**
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+ * find_device_devfreq() - find devfreq struct using device pointer
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+ * @dev: device pointer used to lookup device devfreq.
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+ *
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+ * Search the list of device devfreqs and return the matched device's
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+ * devfreq info. devfreq_list_lock should be held by the caller.
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+ */
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+static struct devfreq *find_device_devfreq(struct device *dev)
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+{
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+ struct devfreq *tmp_devfreq;
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+
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+ if (unlikely(IS_ERR_OR_NULL(dev))) {
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+ pr_err("DEVFREQ: %s: Invalid parameters\n", __func__);
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+ return ERR_PTR(-EINVAL);
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+ }
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+ WARN(!mutex_is_locked(&devfreq_list_lock),
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+ "devfreq_list_lock must be locked.");
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+
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+ list_for_each_entry(tmp_devfreq, &devfreq_list, node) {
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+ if (tmp_devfreq->dev.parent == dev)
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+ return tmp_devfreq;
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+ }
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+
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+ return ERR_PTR(-ENODEV);
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+}
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+
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+/**
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+ * update_devfreq() - Reevaluate the device and configure frequency.
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+ * @devfreq: the devfreq instance.
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+ *
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+ * Note: Lock devfreq->lock before calling update_devfreq
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+ * This function is exported for governors.
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+ */
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+int update_devfreq(struct devfreq *devfreq)
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+{
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+ unsigned long freq;
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+ int err = 0;
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+
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+ if (!mutex_is_locked(&devfreq->lock)) {
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+ WARN(true, "devfreq->lock must be locked by the caller.\n");
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+ return -EINVAL;
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+ }
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+
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+ /* Reevaluate the proper frequency */
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+ err = devfreq->governor->get_target_freq(devfreq, &freq);
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+ if (err)
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+ return err;
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+
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+ err = devfreq->profile->target(devfreq->dev.parent, &freq);
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+ if (err)
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+ return err;
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+
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+ devfreq->previous_freq = freq;
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+ return err;
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+}
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+
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+/**
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+ * devfreq_notifier_call() - Notify that the device frequency requirements
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+ * has been changed out of devfreq framework.
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+ * @nb the notifier_block (supposed to be devfreq->nb)
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+ * @type not used
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+ * @devp not used
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+ *
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+ * Called by a notifier that uses devfreq->nb.
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+ */
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+static int devfreq_notifier_call(struct notifier_block *nb, unsigned long type,
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+ void *devp)
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+{
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+ struct devfreq *devfreq = container_of(nb, struct devfreq, nb);
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+ int ret;
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+
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+ mutex_lock(&devfreq->lock);
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+ ret = update_devfreq(devfreq);
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+ mutex_unlock(&devfreq->lock);
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+
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+ return ret;
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+}
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+
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+/**
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+ * _remove_devfreq() - Remove devfreq from the device.
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+ * @devfreq: the devfreq struct
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+ * @skip: skip calling device_unregister().
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+ *
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+ * Note that the caller should lock devfreq->lock before calling
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+ * this. _remove_devfreq() will unlock it and free devfreq
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+ * internally. devfreq_list_lock should be locked by the caller
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+ * as well (not relased at return)
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+ *
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+ * Lock usage:
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+ * devfreq->lock: locked before call.
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+ * unlocked at return (and freed)
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+ * devfreq_list_lock: locked before call.
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+ * kept locked at return.
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+ * if devfreq is centrally polled.
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+ *
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+ * Freed memory:
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+ * devfreq
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+ */
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+static void _remove_devfreq(struct devfreq *devfreq, bool skip)
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+{
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+ if (!mutex_is_locked(&devfreq->lock)) {
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+ WARN(true, "devfreq->lock must be locked by the caller.\n");
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+ return;
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+ }
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+ if (!devfreq->governor->no_central_polling &&
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+ !mutex_is_locked(&devfreq_list_lock)) {
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+ WARN(true, "devfreq_list_lock must be locked by the caller.\n");
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+ return;
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+ }
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+
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+ if (devfreq->being_removed)
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+ return;
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+
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+ devfreq->being_removed = true;
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+
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+ if (devfreq->profile->exit)
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+ devfreq->profile->exit(devfreq->dev.parent);
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+
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+ if (devfreq->governor->exit)
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+ devfreq->governor->exit(devfreq);
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+
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+ if (!skip && get_device(&devfreq->dev)) {
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+ device_unregister(&devfreq->dev);
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+ put_device(&devfreq->dev);
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+ }
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+
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+ if (!devfreq->governor->no_central_polling)
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+ list_del(&devfreq->node);
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+
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+ mutex_unlock(&devfreq->lock);
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+ mutex_destroy(&devfreq->lock);
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+
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+ kfree(devfreq);
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+}
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+
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+/**
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+ * devfreq_dev_release() - Callback for struct device to release the device.
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+ * @dev: the devfreq device
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+ *
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+ * This calls _remove_devfreq() if _remove_devfreq() is not called.
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+ * Note that devfreq_dev_release() could be called by _remove_devfreq() as
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+ * well as by others unregistering the device.
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+ */
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+static void devfreq_dev_release(struct device *dev)
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+{
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+ struct devfreq *devfreq = to_devfreq(dev);
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+ bool central_polling = !devfreq->governor->no_central_polling;
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+
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+ /*
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+ * If devfreq_dev_release() was called by device_unregister() of
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+ * _remove_devfreq(), we cannot mutex_lock(&devfreq->lock) and
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+ * being_removed is already set. This also partially checks the case
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+ * where devfreq_dev_release() is called from a thread other than
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+ * the one called _remove_devfreq(); however, this case is
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+ * dealt completely with another following being_removed check.
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+ *
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+ * Because being_removed is never being
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+ * unset, we do not need to worry about race conditions on
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+ * being_removed.
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+ */
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+ if (devfreq->being_removed)
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+ return;
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+
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+ if (central_polling)
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+ mutex_lock(&devfreq_list_lock);
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+
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+ mutex_lock(&devfreq->lock);
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+
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+ /*
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+ * Check being_removed flag again for the case where
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+ * devfreq_dev_release() was called in a thread other than the one
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+ * possibly called _remove_devfreq().
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+ */
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+ if (devfreq->being_removed) {
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+ mutex_unlock(&devfreq->lock);
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+ goto out;
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+ }
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+
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+ /* devfreq->lock is unlocked and removed in _removed_devfreq() */
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+ _remove_devfreq(devfreq, true);
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+
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+out:
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+ if (central_polling)
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+ mutex_unlock(&devfreq_list_lock);
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+}
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+
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+/**
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+ * devfreq_monitor() - Periodically poll devfreq objects.
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+ * @work: the work struct used to run devfreq_monitor periodically.
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+ *
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+ */
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+static void devfreq_monitor(struct work_struct *work)
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+{
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+ static unsigned long last_polled_at;
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+ struct devfreq *devfreq, *tmp;
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+ int error;
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+ unsigned long jiffies_passed;
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+ unsigned long next_jiffies = ULONG_MAX, now = jiffies;
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+ struct device *dev;
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+
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+ /* Initially last_polled_at = 0, polling every device at bootup */
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+ jiffies_passed = now - last_polled_at;
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+ last_polled_at = now;
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+ if (jiffies_passed == 0)
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+ jiffies_passed = 1;
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+
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+ mutex_lock(&devfreq_list_lock);
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+ list_for_each_entry_safe(devfreq, tmp, &devfreq_list, node) {
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+ mutex_lock(&devfreq->lock);
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+ dev = devfreq->dev.parent;
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+
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+ /* Do not remove tmp for a while */
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+ wait_remove_device = tmp;
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+
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+ if (devfreq->governor->no_central_polling ||
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+ devfreq->next_polling == 0) {
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+ mutex_unlock(&devfreq->lock);
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+ continue;
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+ }
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+ mutex_unlock(&devfreq_list_lock);
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+
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+ /*
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+ * Reduce more next_polling if devfreq_wq took an extra
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+ * delay. (i.e., CPU has been idled.)
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+ */
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+ if (devfreq->next_polling <= jiffies_passed) {
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+ error = update_devfreq(devfreq);
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+
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+ /* Remove a devfreq with an error. */
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+ if (error && error != -EAGAIN) {
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+
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+ dev_err(dev, "Due to update_devfreq error(%d), devfreq(%s) is removed from the device\n",
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+ error, devfreq->governor->name);
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+
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+ /*
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+ * Unlock devfreq before locking the list
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+ * in order to avoid deadlock with
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+ * find_device_devfreq or others
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+ */
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+ mutex_unlock(&devfreq->lock);
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+ mutex_lock(&devfreq_list_lock);
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+ /* Check if devfreq is already removed */
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+ if (IS_ERR(find_device_devfreq(dev)))
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+ continue;
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+ mutex_lock(&devfreq->lock);
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+ /* This unlocks devfreq->lock and free it */
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+ _remove_devfreq(devfreq, false);
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+ continue;
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+ }
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+ devfreq->next_polling = devfreq->polling_jiffies;
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+ } else {
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+ devfreq->next_polling -= jiffies_passed;
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+ }
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+
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+ if (devfreq->next_polling)
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+ next_jiffies = (next_jiffies > devfreq->next_polling) ?
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+ devfreq->next_polling : next_jiffies;
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+
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+ mutex_unlock(&devfreq->lock);
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+ mutex_lock(&devfreq_list_lock);
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+ }
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+ wait_remove_device = NULL;
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+ mutex_unlock(&devfreq_list_lock);
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+
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+ if (next_jiffies > 0 && next_jiffies < ULONG_MAX) {
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+ polling = true;
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+ queue_delayed_work(devfreq_wq, &devfreq_work, next_jiffies);
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+ } else {
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+ polling = false;
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+ }
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+}
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+
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+/**
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+ * devfreq_add_device() - Add devfreq feature to the device
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+ * @dev: the device to add devfreq feature.
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+ * @profile: device-specific profile to run devfreq.
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+ * @governor: the policy to choose frequency.
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+ * @data: private data for the governor. The devfreq framework does not
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+ * touch this value.
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+ */
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+struct devfreq *devfreq_add_device(struct device *dev,
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+ struct devfreq_dev_profile *profile,
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+ const struct devfreq_governor *governor,
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+ void *data)
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+{
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+ struct devfreq *devfreq;
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+ int err = 0;
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+
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+ if (!dev || !profile || !governor) {
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+ dev_err(dev, "%s: Invalid parameters.\n", __func__);
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+ return ERR_PTR(-EINVAL);
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+ }
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+
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+
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+ if (!governor->no_central_polling) {
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+ mutex_lock(&devfreq_list_lock);
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+ devfreq = find_device_devfreq(dev);
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+ mutex_unlock(&devfreq_list_lock);
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+ if (!IS_ERR(devfreq)) {
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+ dev_err(dev, "%s: Unable to create devfreq for the device. It already has one.\n", __func__);
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+ err = -EINVAL;
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+ goto out;
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+ }
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+ }
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+
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+ devfreq = kzalloc(sizeof(struct devfreq), GFP_KERNEL);
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+ if (!devfreq) {
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+ dev_err(dev, "%s: Unable to create devfreq for the device\n",
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+ __func__);
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+ err = -ENOMEM;
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+ goto out;
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+ }
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+
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+ mutex_init(&devfreq->lock);
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+ mutex_lock(&devfreq->lock);
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+ devfreq->dev.parent = dev;
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+ devfreq->dev.class = devfreq_class;
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+ devfreq->dev.release = devfreq_dev_release;
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+ devfreq->profile = profile;
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+ devfreq->governor = governor;
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+ devfreq->previous_freq = profile->initial_freq;
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+ devfreq->data = data;
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+ devfreq->next_polling = devfreq->polling_jiffies
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+ = msecs_to_jiffies(devfreq->profile->polling_ms);
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+ devfreq->nb.notifier_call = devfreq_notifier_call;
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+
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+ dev_set_name(&devfreq->dev, dev_name(dev));
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+ err = device_register(&devfreq->dev);
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+ if (err) {
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+ put_device(&devfreq->dev);
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+ goto err_dev;
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+ }
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+
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+ if (governor->init)
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+ err = governor->init(devfreq);
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+ if (err)
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+ goto err_init;
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+
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+ mutex_unlock(&devfreq->lock);
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+
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+ if (governor->no_central_polling)
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+ goto out;
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+
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+ mutex_lock(&devfreq_list_lock);
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+
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+ list_add(&devfreq->node, &devfreq_list);
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+
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+ if (devfreq_wq && devfreq->next_polling && !polling) {
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+ polling = true;
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+ queue_delayed_work(devfreq_wq, &devfreq_work,
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+ devfreq->next_polling);
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+ }
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+ mutex_unlock(&devfreq_list_lock);
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+ goto out;
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+err_init:
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+ device_unregister(&devfreq->dev);
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+err_dev:
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+ mutex_unlock(&devfreq->lock);
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+ kfree(devfreq);
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+out:
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+ if (err)
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+ return ERR_PTR(err);
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+ else
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+ return devfreq;
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+}
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+
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+/**
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+ * devfreq_remove_device() - Remove devfreq feature from a device.
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|
|
+ * @devfreq the devfreq instance to be removed
|
|
|
+ */
|
|
|
+int devfreq_remove_device(struct devfreq *devfreq)
|
|
|
+{
|
|
|
+ if (!devfreq)
|
|
|
+ return -EINVAL;
|
|
|
+
|
|
|
+ if (!devfreq->governor->no_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 (!devfreq->governor->no_central_polling)
|
|
|
+ mutex_unlock(&devfreq_list_lock);
|
|
|
+
|
|
|
+ return 0;
|
|
|
+}
|
|
|
+
|
|
|
+static ssize_t show_governor(struct device *dev,
|
|
|
+ struct device_attribute *attr, char *buf)
|
|
|
+{
|
|
|
+ return sprintf(buf, "%s\n", to_devfreq(dev)->governor->name);
|
|
|
+}
|
|
|
+
|
|
|
+static ssize_t show_freq(struct device *dev,
|
|
|
+ struct device_attribute *attr, char *buf)
|
|
|
+{
|
|
|
+ return sprintf(buf, "%lu\n", to_devfreq(dev)->previous_freq);
|
|
|
+}
|
|
|
+
|
|
|
+static ssize_t show_polling_interval(struct device *dev,
|
|
|
+ struct device_attribute *attr, char *buf)
|
|
|
+{
|
|
|
+ return sprintf(buf, "%d\n", to_devfreq(dev)->profile->polling_ms);
|
|
|
+}
|
|
|
+
|
|
|
+static ssize_t store_polling_interval(struct device *dev,
|
|
|
+ struct device_attribute *attr,
|
|
|
+ const char *buf, size_t count)
|
|
|
+{
|
|
|
+ struct devfreq *df = to_devfreq(dev);
|
|
|
+ unsigned int value;
|
|
|
+ int ret;
|
|
|
+
|
|
|
+ ret = sscanf(buf, "%u", &value);
|
|
|
+ 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);
|
|
|
+
|
|
|
+ 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 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),
|
|
|
+ { },
|
|
|
+};
|
|
|
+
|
|
|
+/**
|
|
|
+ * 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_DELAYED_WORK_DEFERRABLE(&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");
|
|
|
+ if (IS_ERR(devfreq_class)) {
|
|
|
+ pr_err("%s: couldn't create class\n", __FILE__);
|
|
|
+ return PTR_ERR(devfreq_class);
|
|
|
+ }
|
|
|
+ devfreq_class->dev_attrs = devfreq_attrs;
|
|
|
+ return 0;
|
|
|
+}
|
|
|
+subsys_initcall(devfreq_init);
|
|
|
+
|
|
|
+static void __exit devfreq_exit(void)
|
|
|
+{
|
|
|
+ class_destroy(devfreq_class);
|
|
|
+}
|
|
|
+module_exit(devfreq_exit);
|
|
|
+
|
|
|
+/*
|
|
|
+ * The followings are helper functions for devfreq user device drivers with
|
|
|
+ * OPP framework.
|
|
|
+ */
|
|
|
+
|
|
|
+/**
|
|
|
+ * devfreq_recommended_opp() - Helper function to get proper OPP for the
|
|
|
+ * freq value given to target callback.
|
|
|
+ * @dev The devfreq user device. (parent of devfreq)
|
|
|
+ * @freq The frequency given to target function
|
|
|
+ *
|
|
|
+ */
|
|
|
+struct opp *devfreq_recommended_opp(struct device *dev, unsigned long *freq)
|
|
|
+{
|
|
|
+ struct opp *opp = opp_find_freq_ceil(dev, freq);
|
|
|
+
|
|
|
+ if (opp == ERR_PTR(-ENODEV))
|
|
|
+ opp = opp_find_freq_floor(dev, freq);
|
|
|
+ return opp;
|
|
|
+}
|
|
|
+
|
|
|
+/**
|
|
|
+ * devfreq_register_opp_notifier() - Helper function to get devfreq notified
|
|
|
+ * for any changes in the OPP availability
|
|
|
+ * changes
|
|
|
+ * @dev The devfreq user device. (parent of devfreq)
|
|
|
+ * @devfreq The devfreq object.
|
|
|
+ */
|
|
|
+int devfreq_register_opp_notifier(struct device *dev, struct devfreq *devfreq)
|
|
|
+{
|
|
|
+ struct srcu_notifier_head *nh = opp_get_notifier(dev);
|
|
|
+
|
|
|
+ if (IS_ERR(nh))
|
|
|
+ return PTR_ERR(nh);
|
|
|
+ return srcu_notifier_chain_register(nh, &devfreq->nb);
|
|
|
+}
|
|
|
+
|
|
|
+/**
|
|
|
+ * devfreq_unregister_opp_notifier() - Helper function to stop getting devfreq
|
|
|
+ * notified for any changes in the OPP
|
|
|
+ * availability changes anymore.
|
|
|
+ * @dev The devfreq user device. (parent of devfreq)
|
|
|
+ * @devfreq The devfreq object.
|
|
|
+ *
|
|
|
+ * At exit() callback of devfreq_dev_profile, this must be included if
|
|
|
+ * devfreq_recommended_opp is used.
|
|
|
+ */
|
|
|
+int devfreq_unregister_opp_notifier(struct device *dev, struct devfreq *devfreq)
|
|
|
+{
|
|
|
+ struct srcu_notifier_head *nh = opp_get_notifier(dev);
|
|
|
+
|
|
|
+ if (IS_ERR(nh))
|
|
|
+ return PTR_ERR(nh);
|
|
|
+ return srcu_notifier_chain_unregister(nh, &devfreq->nb);
|
|
|
+}
|
|
|
+
|
|
|
+MODULE_AUTHOR("MyungJoo Ham <myungjoo.ham@samsung.com>");
|
|
|
+MODULE_DESCRIPTION("devfreq class support");
|
|
|
+MODULE_LICENSE("GPL");
|
Rafael J. Wysocki