--- /dev/null
+/*
+ * devfreq: Generic Dynamic Voltage and Frequency Scaling (DVFS) Framework
+ * for Non-CPU Devices.
+ *
+ * Copyright (C) 2011 Samsung Electronics
+ * MyungJoo Ham <myungjoo.ham@samsung.com>
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License version 2 as
+ * published by the Free Software Foundation.
+ */
+
+#include <linux/kernel.h>
+#include <linux/sched.h>
+#include <linux/errno.h>
+#include <linux/err.h>
+#include <linux/init.h>
+#include <linux/slab.h>
+#include <linux/opp.h>
+#include <linux/devfreq.h>
+#include <linux/workqueue.h>
+#include <linux/platform_device.h>
+#include <linux/list.h>
+#include <linux/printk.h>
+#include <linux/hrtimer.h>
+#include "governor.h"
+
+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.
+ */
+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);
+static DEFINE_MUTEX(devfreq_list_lock);
+
+/**
+ * find_device_devfreq() - find devfreq struct using device pointer
+ * @dev: device pointer used to lookup device devfreq.
+ *
+ * Search the list of device devfreqs and return the matched device's
+ * devfreq info. devfreq_list_lock should be held by the caller.
+ */
+static struct devfreq *find_device_devfreq(struct device *dev)
+{
+ struct devfreq *tmp_devfreq;
+
+ if (unlikely(IS_ERR_OR_NULL(dev))) {
+ pr_err("DEVFREQ: %s: Invalid parameters\n", __func__);
+ return ERR_PTR(-EINVAL);
+ }
+ WARN(!mutex_is_locked(&devfreq_list_lock),
+ "devfreq_list_lock must be locked.");
+
+ list_for_each_entry(tmp_devfreq, &devfreq_list, node) {
+ if (tmp_devfreq->dev.parent == dev)
+ return tmp_devfreq;
+ }
+
+ return ERR_PTR(-ENODEV);
+}
+
+/**
+ * update_devfreq() - Reevaluate the device and configure frequency.
+ * @devfreq: the devfreq instance.
+ *
+ * Note: Lock devfreq->lock before calling update_devfreq
+ * This function is exported for governors.
+ */
+int update_devfreq(struct devfreq *devfreq)
+{
+ unsigned long freq;
+ int err = 0;
+
+ if (!mutex_is_locked(&devfreq->lock)) {
+ WARN(true, "devfreq->lock must be locked by the caller.\n");
+ return -EINVAL;
+ }
+
+ /* Reevaluate the proper frequency */
+ err = devfreq->governor->get_target_freq(devfreq, &freq);
+ if (err)
+ return err;
+
+ err = devfreq->profile->target(devfreq->dev.parent, &freq);
+ if (err)
+ return err;
+
+ devfreq->previous_freq = freq;
+ return err;
+}
+
+/**
+ * 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)
+ * @type not used
+ * @devp not used
+ *
+ * Called by a notifier that uses devfreq->nb.
+ */
+static int devfreq_notifier_call(struct notifier_block *nb, unsigned long type,
+ void *devp)
+{
+ struct devfreq *devfreq = container_of(nb, struct devfreq, nb);
+ int ret;
+
+ mutex_lock(&devfreq->lock);
+ ret = update_devfreq(devfreq);
+ mutex_unlock(&devfreq->lock);
+
+ return ret;
+}
+
+/**
+ * _remove_devfreq() - Remove devfreq from the device.
+ * @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");
+ return;
+ }
+
+ if (devfreq->being_removed)
+ return;
+
+ devfreq->being_removed = true;
+
+ 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);
+}
+
+/**
+ * devfreq_dev_release() - Callback for struct device to release the device.
+ * @dev: the devfreq device
+ *
+ * This calls _remove_devfreq() if _remove_devfreq() is not called.
+ * Note that devfreq_dev_release() could be called by _remove_devfreq() as
+ * well as by others unregistering the device.
+ */
+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;
+ }
+}
+
+/**
+ * devfreq_add_device() - Add devfreq feature to the device
+ * @dev: the device to add devfreq feature.
+ * @profile: device-specific profile to run devfreq.
+ * @governor: the policy to choose frequency.
+ * @data: private data for the governor. The devfreq framework does not
+ * touch this value.
+ */
+struct devfreq *devfreq_add_device(struct device *dev,
+ struct devfreq_dev_profile *profile,
+ const struct devfreq_governor *governor,
+ void *data)
+{
+ struct devfreq *devfreq;
+ int err = 0;
+
+ if (!dev || !profile || !governor) {
+ dev_err(dev, "%s: Invalid parameters.\n", __func__);
+ 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 out;
+ }
+ }
+
+ devfreq = kzalloc(sizeof(struct devfreq), GFP_KERNEL);
+ if (!devfreq) {
+ dev_err(dev, "%s: Unable to create devfreq for the device\n",
+ __func__);
+ err = -ENOMEM;
+ goto out;
+ }
+
+ mutex_init(&devfreq->lock);
+ mutex_lock(&devfreq->lock);
+ devfreq->dev.parent = dev;
+ devfreq->dev.class = devfreq_class;
+ devfreq->dev.release = devfreq_dev_release;
+ devfreq->profile = profile;
+ 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);
+ 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);
+
+ if (devfreq_wq && devfreq->next_polling && !polling) {
+ polling = true;
+ queue_delayed_work(devfreq_wq, &devfreq_work,
+ devfreq->next_polling);
+ }
+ mutex_unlock(&devfreq_list_lock);
+ goto out;
+err_init:
+ device_unregister(&devfreq->dev);
+err_dev:
+ mutex_unlock(&devfreq->lock);
+ kfree(devfreq);
+out:
+ if (err)
+ return ERR_PTR(err);
+ else
+ return devfreq;
+}
+
+/**
+ * devfreq_remove_device() - Remove devfreq feature from a device.
+ * @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;
+}
+
+/**
+ * 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);
+ }
+ 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");
--- /dev/null
+/*
+ * devfreq: Generic Dynamic Voltage and Frequency Scaling (DVFS) Framework
+ * for Non-CPU Devices.
+ *
+ * Copyright (C) 2011 Samsung Electronics
+ * MyungJoo Ham <myungjoo.ham@samsung.com>
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License version 2 as
+ * published by the Free Software Foundation.
+ */
+
+#ifndef __LINUX_DEVFREQ_H__
+#define __LINUX_DEVFREQ_H__
+
+#include <linux/device.h>
+#include <linux/notifier.h>
+#include <linux/opp.h>
+
+#define DEVFREQ_NAME_LEN 16
+
+struct devfreq;
+
+/**
+ * struct devfreq_dev_status - Data given from devfreq user device to
+ * governors. Represents the performance
+ * statistics.
+ * @total_time The total time represented by this instance of
+ * devfreq_dev_status
+ * @busy_time The time that the device was working among the
+ * total_time.
+ * @current_frequency The operating frequency.
+ * @private_data An entry not specified by the devfreq framework.
+ * A device and a specific governor may have their
+ * own protocol with private_data. However, because
+ * this is governor-specific, a governor using this
+ * will be only compatible with devices aware of it.
+ */
+struct devfreq_dev_status {
+ /* both since the last measure */
+ unsigned long total_time;
+ unsigned long busy_time;
+ unsigned long current_frequency;
+ void *private_date;
+};
+
+/**
+ * struct devfreq_dev_profile - Devfreq's user device profile
+ * @initial_freq The operating frequency when devfreq_add_device() is
+ * called.
+ * @polling_ms The polling interval in ms. 0 disables polling.
+ * @target The device should set its operating frequency at
+ * freq or lowest-upper-than-freq value. If freq is
+ * higher than any operable frequency, set maximum.
+ * Before returning, target function should set
+ * freq at the current frequency.
+ * @get_dev_status The device should provide the current performance
+ * status to devfreq, which is used by governors.
+ * @exit An optional callback that is called when devfreq
+ * is removing the devfreq object due to error or
+ * from devfreq_remove_device() call. If the user
+ * has registered devfreq->nb at a notifier-head,
+ * this is the time to unregister it.
+ */
+struct devfreq_dev_profile {
+ unsigned long initial_freq;
+ unsigned int polling_ms;
+
+ int (*target)(struct device *dev, unsigned long *freq);
+ int (*get_dev_status)(struct device *dev,
+ struct devfreq_dev_status *stat);
+ void (*exit)(struct device *dev);
+};
+
+/**
+ * struct devfreq_governor - Devfreq policy governor
+ * @name Governor's name
+ * @get_target_freq Returns desired operating frequency for the device.
+ * Basically, get_target_freq will run
+ * devfreq_dev_profile.get_dev_status() to get the
+ * status of the device (load = busy_time / total_time).
+ * If no_central_polling is set, this callback is called
+ * only with update_devfreq() notified by OPP.
+ * @init Called when the devfreq is being attached to a device
+ * @exit Called when the devfreq is being removed from a
+ * device. Governor should stop any internal routines
+ * before return because related data may be
+ * freed after exit().
+ * @no_central_polling Do not use devfreq's central polling mechanism.
+ * When this is set, devfreq will not call
+ * get_target_freq with devfreq_monitor(). However,
+ * devfreq will call get_target_freq with
+ * devfreq_update() notified by OPP framework.
+ *
+ * Note that the callbacks are called with devfreq->lock locked by devfreq.
+ */
+struct devfreq_governor {
+ const char name[DEVFREQ_NAME_LEN];
+ int (*get_target_freq)(struct devfreq *this, unsigned long *freq);
+ int (*init)(struct devfreq *this);
+ void (*exit)(struct devfreq *this);
+ const bool no_central_polling;
+};
+
+/**
+ * struct devfreq - Device devfreq structure
+ * @node list node - contains the devices with devfreq that have been
+ * registered.
+ * @lock a mutex to protect accessing devfreq.
+ * @dev device registered by devfreq class. dev.parent is the device
+ * using devfreq.
+ * @profile device-specific devfreq profile
+ * @governor method how to choose frequency based on the usage.
+ * @nb notifier block used to notify devfreq object that it should
+ * reevaluate operable frequencies. Devfreq users may use
+ * devfreq.nb to the corresponding register notifier call chain.
+ * @polling_jiffies interval in jiffies.
+ * @previous_freq previously configured frequency value.
+ * @next_polling the number of remaining jiffies to poll with
+ * "devfreq_monitor" executions to reevaluate
+ * frequency/voltage of the device. Set by
+ * profile's polling_ms interval.
+ * @data Private data of the governor. The devfreq framework does not
+ * touch this.
+ * @being_removed a flag to mark that this object is being removed in
+ * order to prevent trying to remove the object multiple times.
+ *
+ * This structure stores the devfreq information for a give device.
+ *
+ * Note that when a governor accesses entries in struct devfreq in its
+ * functions except for the context of callbacks defined in struct
+ * devfreq_governor, the governor should protect its access with the
+ * struct mutex lock in struct devfreq. A governor may use this mutex
+ * to protect its own private data in void *data as well.
+ */
+struct devfreq {
+ struct list_head node;
+
+ struct mutex lock;
+ struct device dev;
+ struct devfreq_dev_profile *profile;
+ const struct devfreq_governor *governor;
+ struct notifier_block nb;
+
+ unsigned long polling_jiffies;
+ unsigned long previous_freq;
+ unsigned int next_polling;
+
+ void *data; /* private data for governors */
+
+ bool being_removed;
+};
+
+#if defined(CONFIG_PM_DEVFREQ)
+extern struct devfreq *devfreq_add_device(struct device *dev,
+ struct devfreq_dev_profile *profile,
+ const struct devfreq_governor *governor,
+ void *data);
+extern int devfreq_remove_device(struct devfreq *devfreq);
+
+/* Helper functions for devfreq user device driver with OPP. */
+extern struct opp *devfreq_recommended_opp(struct device *dev,
+ unsigned long *freq);
+extern int devfreq_register_opp_notifier(struct device *dev,
+ struct devfreq *devfreq);
+extern int devfreq_unregister_opp_notifier(struct device *dev,
+ struct devfreq *devfreq);
+
+#else /* !CONFIG_PM_DEVFREQ */
+static struct devfreq *devfreq_add_device(struct device *dev,
+ struct devfreq_dev_profile *profile,
+ struct devfreq_governor *governor,
+ void *data);
+{
+ return NULL;
+}
+
+static int devfreq_remove_device(struct devfreq *devfreq);
+{
+ return 0;
+}
+
+static struct opp *devfreq_recommended_opp(struct device *dev,
+ unsigned long *freq)
+{
+ return -EINVAL;
+}
+
+static int devfreq_register_opp_notifier(struct device *dev,
+ struct devfreq *devfreq)
+{
+ return -EINVAL;
+}
+
+static int devfreq_unregister_opp_notifier(struct device *dev,
+ struct devfreq *devfreq)
+{
+ return -EINVAL;
+}
+
+#endif /* CONFIG_PM_DEVFREQ */
+
+#endif /* __LINUX_DEVFREQ_H__ */
projects / platform / kernel / linux-3.10.git / commitdiff