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Merge branch 'pm-devfreq' into pm-for-linus

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* pm-devfreq:
  PM / devfreq: Add basic governors
  PM / devfreq: Add common sysfs interfaces
  PM: Introduce devfreq: generic DVFS framework with device-specific OPPs
  PM / OPP: Add OPP availability change notifier.
This commit is contained in:
Rafael J. Wysocki 2011-10-07 23:17:18 +02:00
commit 7811ac276b
14 changed files with 1303 additions and 0 deletions
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52
Documentation/ABI/testing/sysfs-class-devfreq Normal file
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@ -0,0 +1,52 @@
What: /sys/class/devfreq/.../
Date: September 2011
Contact: MyungJoo Ham <myungjoo.ham@samsung.com>
Description:
Provide a place in sysfs for the devfreq objects.
This allows accessing various devfreq specific variables.
The name of devfreq object denoted as ... is same as the
name of device using devfreq.
What: /sys/class/devfreq/.../governor
Date: September 2011
Contact: MyungJoo Ham <myungjoo.ham@samsung.com>
Description:
The /sys/class/devfreq/.../governor shows the name of the
governor used by the corresponding devfreq object.
What: /sys/class/devfreq/.../cur_freq
Date: September 2011
Contact: MyungJoo Ham <myungjoo.ham@samsung.com>
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>
Description:
The /sys/class/devfreq/.../polling_interval shows and sets
the requested polling interval of the corresponding devfreq
object. The values are represented in ms. If the value is
less than 1 jiffy, it is considered to be 0, which means
no polling. This value is meaningless if the governor is
not polling; thus. If the governor is not using
devfreq-provided central polling
(/sys/class/devfreq/.../central_polling is 0), this value
may be useless.
What: /sys/class/devfreq/.../userspace/set_freq
Date: September 2011
Contact: MyungJoo Ham <myungjoo.ham@samsung.com>
Description:
The /sys/class/devfreq/.../userspace/set_freq shows and
sets the requested frequency for the devfreq object if
userspace governor is in effect.

2
drivers/Kconfig
View File

@ -130,4 +130,6 @@ source "drivers/iommu/Kconfig"
source "drivers/virt/Kconfig"
source "drivers/devfreq/Kconfig"
endmenu

2
drivers/Makefile
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@ -127,3 +127,5 @@ obj-$(CONFIG_IOMMU_SUPPORT) += iommu/
# Virtualization drivers
obj-$(CONFIG_VIRT_DRIVERS) += virt/
obj-$(CONFIG_PM_DEVFREQ) += devfreq/

30
drivers/base/power/opp.c
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@ -73,6 +73,7 @@ struct opp {
* RCU usage: nodes are not modified in the list of device_opp,
* however addition is possible and is secured by dev_opp_list_lock
* @dev: device pointer
* @head: notifier head to notify the OPP availability changes.
* @opp_list: list of opps
*
* This is an internal data structure maintaining the link to opps attached to
@ -83,6 +84,7 @@ struct device_opp {
struct list_head node;
struct device *dev;
struct srcu_notifier_head head;
struct list_head opp_list;
};
@ -404,6 +406,7 @@ int opp_add(struct device *dev, unsigned long freq, unsigned long u_volt)
}
dev_opp->dev = dev;
srcu_init_notifier_head(&dev_opp->head);
INIT_LIST_HEAD(&dev_opp->opp_list);
/* Secure the device list modification */
@ -428,6 +431,11 @@ int opp_add(struct device *dev, unsigned long freq, unsigned long u_volt)
list_add_rcu(&new_opp->node, head);
mutex_unlock(&dev_opp_list_lock);
/*
* Notify the changes in the availability of the operable
* frequency/voltage list.
*/
srcu_notifier_call_chain(&dev_opp->head, OPP_EVENT_ADD, new_opp);
return 0;
}
@ -504,6 +512,14 @@ static int opp_set_availability(struct device *dev, unsigned long freq,
mutex_unlock(&dev_opp_list_lock);
synchronize_rcu();
/* Notify the change of the OPP availability */
if (availability_req)
srcu_notifier_call_chain(&dev_opp->head, OPP_EVENT_ENABLE,
new_opp);
else
srcu_notifier_call_chain(&dev_opp->head, OPP_EVENT_DISABLE,
new_opp);
/* clean up old opp */
new_opp = opp;
goto out;
@ -643,3 +659,17 @@ void opp_free_cpufreq_table(struct device *dev,
*table = NULL;
}
#endif /* CONFIG_CPU_FREQ */
/**
* opp_get_notifier() - find notifier_head of the device with opp
* @dev: device pointer used to lookup device OPPs.
*/
struct srcu_notifier_head *opp_get_notifier(struct device *dev)
{
struct device_opp *dev_opp = find_device_opp(dev);
if (IS_ERR(dev_opp))
return ERR_PTR(PTR_ERR(dev_opp)); /* matching type */
return &dev_opp->head;
}

75
drivers/devfreq/Kconfig Normal file
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@ -0,0 +1,75 @@
config ARCH_HAS_DEVFREQ
bool
depends on ARCH_HAS_OPP
help
Denotes that the architecture supports DEVFREQ. If the architecture
supports multiple OPP entries per device and the frequency of the
devices with OPPs may be altered dynamically, the architecture
supports DEVFREQ.
menuconfig PM_DEVFREQ
bool "Generic Dynamic Voltage and Frequency Scaling (DVFS) support"
depends on PM_OPP && ARCH_HAS_DEVFREQ
help
With OPP support, a device may have a list of frequencies and
voltages available. DEVFREQ, a generic DVFS framework can be
registered for a device with OPP support in order to let the
governor provided to DEVFREQ choose an operating frequency
based on the OPP's list and the policy given with DEVFREQ.
Each device may have its own governor and policy. DEVFREQ can
reevaluate the device state periodically and/or based on the
OPP list changes (each frequency/voltage pair in OPP may be
disabled or enabled).
Like some CPUs with CPUFREQ, a device may have multiple clocks.
However, because the clock frequencies of a single device are
determined by the single device's state, an instance of DEVFREQ
is attached to a single device and returns a "representative"
clock frequency from the OPP of the device, which is also attached
to a device by 1-to-1. The device registering DEVFREQ takes the
responsiblity to "interpret" the frequency listed in OPP and
to set its every clock accordingly with the "target" callback
given to DEVFREQ.
if PM_DEVFREQ
comment "DEVFREQ Governors"
config DEVFREQ_GOV_SIMPLE_ONDEMAND
bool "Simple Ondemand"
help
Chooses frequency based on the recent load on the device. Works
similar as ONDEMAND governor of CPUFREQ does. A device with
Simple-Ondemand should be able to provide busy/total counter
values that imply the usage rate. A device may provide tuned
values to the governor with data field at devfreq_add_device().
config DEVFREQ_GOV_PERFORMANCE
bool "Performance"
help
Sets the frequency at the maximum available frequency.
This governor always returns UINT_MAX as frequency so that
the DEVFREQ framework returns the highest frequency available
at any time.
config DEVFREQ_GOV_POWERSAVE
bool "Powersave"
help
Sets the frequency at the minimum available frequency.
This governor always returns 0 as frequency so that
the DEVFREQ framework returns the lowest frequency available
at any time.
config DEVFREQ_GOV_USERSPACE
bool "Userspace"
help
Sets the frequency at the user specified one.
This governor returns the user configured frequency if there
has been an input to /sys/devices/.../power/devfreq_set_freq.
Otherwise, the governor does not change the frequnecy
given at the initialization.
comment "DEVFREQ Drivers"
endif # PM_DEVFREQ

5
drivers/devfreq/Makefile Normal file
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@ -0,0 +1,5 @@
obj-$(CONFIG_PM_DEVFREQ) += devfreq.o
obj-$(CONFIG_DEVFREQ_GOV_SIMPLE_ONDEMAND) += governor_simpleondemand.o
obj-$(CONFIG_DEVFREQ_GOV_PERFORMANCE) += governor_performance.o
obj-$(CONFIG_DEVFREQ_GOV_POWERSAVE) += governor_powersave.o
obj-$(CONFIG_DEVFREQ_GOV_USERSPACE) += governor_userspace.o

601
drivers/devfreq/devfreq.c Normal file
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@ -0,0 +1,601 @@
/*
* 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;
}
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");

24
drivers/devfreq/governor.h Normal file
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@ -0,0 +1,24 @@
/*
* governor.h - internal header for devfreq governors.
*
* 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.
*
* This header is for devfreq governors in drivers/devfreq/
*/
#ifndef _GOVERNOR_H
#define _GOVERNOR_H
#include <linux/devfreq.h>
#define to_devfreq(DEV) container_of((DEV), struct devfreq, dev)
/* Caution: devfreq->lock must be locked before calling update_devfreq */
extern int update_devfreq(struct devfreq *devfreq);
#endif /* _GOVERNOR_H */

29
drivers/devfreq/governor_performance.c Normal file
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@ -0,0 +1,29 @@
/*
* linux/drivers/devfreq/governor_performance.c
*
* 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/devfreq.h>
static int devfreq_performance_func(struct devfreq *df,
unsigned long *freq)
{
/*
* target callback should be able to get floor value as
* said in devfreq.h
*/
*freq = UINT_MAX;
return 0;
}
const struct devfreq_governor devfreq_performance = {
.name = "performance",
.get_target_freq = devfreq_performance_func,
.no_central_polling = true,
};

29
drivers/devfreq/governor_powersave.c Normal file
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@ -0,0 +1,29 @@
/*
* linux/drivers/devfreq/governor_powersave.c
*
* 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/devfreq.h>
static int devfreq_powersave_func(struct devfreq *df,
unsigned long *freq)
{
/*
* target callback should be able to get ceiling value as
* said in devfreq.h
*/
*freq = 0;
return 0;
}
const struct devfreq_governor devfreq_powersave = {
.name = "powersave",
.get_target_freq = devfreq_powersave_func,
.no_central_polling = true,
};

88
drivers/devfreq/governor_simpleondemand.c Normal file
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@ -0,0 +1,88 @@
/*
* linux/drivers/devfreq/governor_simpleondemand.c
*
* 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/errno.h>
#include <linux/devfreq.h>
#include <linux/math64.h>
/* Default constants for DevFreq-Simple-Ondemand (DFSO) */
#define DFSO_UPTHRESHOLD (90)
#define DFSO_DOWNDIFFERENCTIAL (5)
static int devfreq_simple_ondemand_func(struct devfreq *df,
unsigned long *freq)
{
struct devfreq_dev_status stat;
int err = df->profile->get_dev_status(df->dev.parent, &stat);
unsigned long long a, b;
unsigned int dfso_upthreshold = DFSO_UPTHRESHOLD;
unsigned int dfso_downdifferential = DFSO_DOWNDIFFERENCTIAL;
struct devfreq_simple_ondemand_data *data = df->data;
if (err)
return err;
if (data) {
if (data->upthreshold)
dfso_upthreshold = data->upthreshold;
if (data->downdifferential)
dfso_downdifferential = data->downdifferential;
}
if (dfso_upthreshold > 100 ||
dfso_upthreshold < dfso_downdifferential)
return -EINVAL;
/* Assume MAX if it is going to be divided by zero */
if (stat.total_time == 0) {
*freq = UINT_MAX;
return 0;
}
/* Prevent overflow */
if (stat.busy_time >= (1 << 24) || stat.total_time >= (1 << 24)) {
stat.busy_time >>= 7;
stat.total_time >>= 7;
}
/* Set MAX if it's busy enough */
if (stat.busy_time * 100 >
stat.total_time * dfso_upthreshold) {
*freq = UINT_MAX;
return 0;
}
/* Set MAX if we do not know the initial frequency */
if (stat.current_frequency == 0) {
*freq = UINT_MAX;
return 0;
}
/* Keep the current frequency */
if (stat.busy_time * 100 >
stat.total_time * (dfso_upthreshold - dfso_downdifferential)) {
*freq = stat.current_frequency;
return 0;
}
/* Set the desired frequency based on the load */
a = stat.busy_time;
a *= stat.current_frequency;
b = div_u64(a, stat.total_time);
b *= 100;
b = div_u64(b, (dfso_upthreshold - dfso_downdifferential / 2));
*freq = (unsigned long) b;
return 0;
}
const struct devfreq_governor devfreq_simple_ondemand = {
.name = "simple_ondemand",
.get_target_freq = devfreq_simple_ondemand_func,
};

116
drivers/devfreq/governor_userspace.c Normal file
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@ -0,0 +1,116 @@
/*
* linux/drivers/devfreq/governor_simpleondemand.c
*
* 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/slab.h>
#include <linux/device.h>
#include <linux/devfreq.h>
#include <linux/pm.h>
#include <linux/mutex.h>
#include "governor.h"
struct userspace_data {
unsigned long user_frequency;
bool valid;
};
static int devfreq_userspace_func(struct devfreq *df, unsigned long *freq)
{
struct userspace_data *data = df->data;
if (!data->valid)
*freq = df->previous_freq; /* No user freq specified yet */
else
*freq = data->user_frequency;
return 0;
}
static ssize_t store_freq(struct device *dev, struct device_attribute *attr,
const char *buf, size_t count)
{
struct devfreq *devfreq = to_devfreq(dev);
struct userspace_data *data;
unsigned long wanted;
int err = 0;
mutex_lock(&devfreq->lock);
data = devfreq->data;
sscanf(buf, "%lu", &wanted);
data->user_frequency = wanted;
data->valid = true;
err = update_devfreq(devfreq);
if (err == 0)
err = count;
mutex_unlock(&devfreq->lock);
return err;
}
static ssize_t show_freq(struct device *dev, struct device_attribute *attr,
char *buf)
{
struct devfreq *devfreq = to_devfreq(dev);
struct userspace_data *data;
int err = 0;
mutex_lock(&devfreq->lock);
data = devfreq->data;
if (data->valid)
err = sprintf(buf, "%lu\n", data->user_frequency);
else
err = sprintf(buf, "undefined\n");
mutex_unlock(&devfreq->lock);
return err;
}
static DEVICE_ATTR(set_freq, 0644, show_freq, store_freq);
static struct attribute *dev_entries[] = {
&dev_attr_set_freq.attr,
NULL,
};
static struct attribute_group dev_attr_group = {
.name = "userspace",
.attrs = dev_entries,
};
static int userspace_init(struct devfreq *devfreq)
{
int err = 0;
struct userspace_data *data = kzalloc(sizeof(struct userspace_data),
GFP_KERNEL);
if (!data) {
err = -ENOMEM;
goto out;
}
data->valid = false;
devfreq->data = data;
err = sysfs_create_group(&devfreq->dev.kobj, &dev_attr_group);
out:
return err;
}
static void userspace_exit(struct devfreq *devfreq)
{
sysfs_remove_group(&devfreq->dev.kobj, &dev_attr_group);
kfree(devfreq->data);
devfreq->data = NULL;
}
const struct devfreq_governor devfreq_userspace = {
.name = "userspace",
.get_target_freq = devfreq_userspace_func,
.init = userspace_init,
.exit = userspace_exit,
.no_central_polling = true,
};

238
include/linux/devfreq.h Normal file
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@ -0,0 +1,238 @@
/*
* 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);
#ifdef CONFIG_DEVFREQ_GOV_POWERSAVE
extern const struct devfreq_governor devfreq_powersave;
#endif
#ifdef CONFIG_DEVFREQ_GOV_PERFORMANCE
extern const struct devfreq_governor devfreq_performance;
#endif
#ifdef CONFIG_DEVFREQ_GOV_USERSPACE
extern const struct devfreq_governor devfreq_userspace;
#endif
#ifdef CONFIG_DEVFREQ_GOV_SIMPLE_ONDEMAND
extern const struct devfreq_governor devfreq_simple_ondemand;
/**
* struct devfreq_simple_ondemand_data - void *data fed to struct devfreq
* and devfreq_add_device
* @ upthreshold If the load is over this value, the frequency jumps.
* Specify 0 to use the default. Valid value = 0 to 100.
* @ downdifferential If the load is under upthreshold - downdifferential,
* the governor may consider slowing the frequency down.
* Specify 0 to use the default. Valid value = 0 to 100.
* downdifferential < upthreshold must hold.
*
* If the fed devfreq_simple_ondemand_data pointer is NULL to the governor,
* the governor uses the default values.
*/
struct devfreq_simple_ondemand_data {
unsigned int upthreshold;
unsigned int downdifferential;
};
#endif
#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;
}
#define devfreq_powersave NULL
#define devfreq_performance NULL
#define devfreq_userspace NULL
#define devfreq_simple_ondemand NULL
#endif /* CONFIG_PM_DEVFREQ */
#endif /* __LINUX_DEVFREQ_H__ */

12
include/linux/opp.h
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@ -16,9 +16,14 @@
#include <linux/err.h>
#include <linux/cpufreq.h>
#include <linux/notifier.h>
struct opp;
enum opp_event {
OPP_EVENT_ADD, OPP_EVENT_ENABLE, OPP_EVENT_DISABLE,
};
#if defined(CONFIG_PM_OPP)
unsigned long opp_get_voltage(struct opp *opp);
@ -40,6 +45,8 @@ int opp_enable(struct device *dev, unsigned long freq);
int opp_disable(struct device *dev, unsigned long freq);
struct srcu_notifier_head *opp_get_notifier(struct device *dev);
#else
static inline unsigned long opp_get_voltage(struct opp *opp)
{
@ -89,6 +96,11 @@ static inline int opp_disable(struct device *dev, unsigned long freq)
{
return 0;
}
struct srcu_notifier_head *opp_get_notifier(struct device *dev)
{
return ERR_PTR(-EINVAL);
}
#endif /* CONFIG_PM */
#if defined(CONFIG_CPU_FREQ) && defined(CONFIG_PM_OPP)