diff options
| -rw-r--r-- | drivers/Kconfig | 2 | ||||
| -rw-r--r-- | drivers/Makefile | 2 | ||||
| -rw-r--r-- | drivers/devfreq/Kconfig | 39 | ||||
| -rw-r--r-- | drivers/devfreq/Makefile | 1 | ||||
| -rw-r--r-- | drivers/devfreq/devfreq.c | 532 | ||||
| -rw-r--r-- | drivers/devfreq/governor.h | 24 | ||||
| -rw-r--r-- | include/linux/devfreq.h | 203 |
7 files changed, 803 insertions, 0 deletions
diff --git a/drivers/Kconfig b/drivers/Kconfig index 95b9e7eefad..a1efd75070a 100644 --- a/drivers/Kconfig +++ b/drivers/Kconfig @@ -130,4 +130,6 @@ source "drivers/iommu/Kconfig" source "drivers/virt/Kconfig" +source "drivers/devfreq/Kconfig" + endmenu diff --git a/drivers/Makefile b/drivers/Makefile index 7fa433a7030..97c957b5081 100644 --- a/drivers/Makefile +++ b/drivers/Makefile @@ -127,3 +127,5 @@ obj-$(CONFIG_IOMMU_SUPPORT) += iommu/ # Virtualization drivers obj-$(CONFIG_VIRT_DRIVERS) += virt/ + +obj-$(CONFIG_PM_DEVFREQ) += devfreq/ diff --git a/drivers/devfreq/Kconfig b/drivers/devfreq/Kconfig new file mode 100644 index 00000000000..1fb42de4f42 --- /dev/null +++ b/drivers/devfreq/Kconfig @@ -0,0 +1,39 @@ +config ARCH_HAS_DEVFREQ + bool + depends on ARCH_HAS_OPP + help + Denotes that the architecture supports DEVFREQ. If the architecture + supports multiple OPP entries per device and the frequency of the + devices with OPPs may be altered dynamically, the architecture + supports DEVFREQ. + +menuconfig PM_DEVFREQ + bool "Generic Dynamic Voltage and Frequency Scaling (DVFS) support" + depends on PM_OPP && ARCH_HAS_DEVFREQ + help + With OPP support, a device may have a list of frequencies and + voltages available. DEVFREQ, a generic DVFS framework can be + registered for a device with OPP support in order to let the + governor provided to DEVFREQ choose an operating frequency + based on the OPP's list and the policy given with DEVFREQ. + + Each device may have its own governor and policy. DEVFREQ can + reevaluate the device state periodically and/or based on the + OPP list changes (each frequency/voltage pair in OPP may be + disabled or enabled). + + Like some CPUs with CPUFREQ, a device may have multiple clocks. + However, because the clock frequencies of a single device are + determined by the single device's state, an instance of DEVFREQ + is attached to a single device and returns a "representative" + clock frequency from the OPP of the device, which is also attached + to a device by 1-to-1. The device registering DEVFREQ takes the + responsiblity to "interpret" the frequency listed in OPP and + to set its every clock accordingly with the "target" callback + given to DEVFREQ. + +if PM_DEVFREQ + +comment "DEVFREQ Drivers" + +endif # PM_DEVFREQ diff --git a/drivers/devfreq/Makefile b/drivers/devfreq/Makefile new file mode 100644 index 00000000000..168934a12b3 --- /dev/null +++ b/drivers/devfreq/Makefile @@ -0,0 +1 @@ +obj-$(CONFIG_PM_DEVFREQ) += devfreq.o diff --git a/drivers/devfreq/devfreq.c b/drivers/devfreq/devfreq.c new file mode 100644 index 00000000000..f3100b19f79 --- /dev/null +++ b/drivers/devfreq/devfreq.c @@ -0,0 +1,532 @@ +/* + * 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"); diff --git a/drivers/devfreq/governor.h b/drivers/devfreq/governor.h new file mode 100644 index 00000000000..ea7f13c58de --- /dev/null +++ b/drivers/devfreq/governor.h @@ -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 */ diff --git a/include/linux/devfreq.h b/include/linux/devfreq.h new file mode 100644 index 00000000000..b3be3d3cbaa --- /dev/null +++ b/include/linux/devfreq.h @@ -0,0 +1,203 @@ +/* + * 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__ */ |