drivers/cpufreq/cpufreq_governor.c - arm/linux-arm-legacy - Git at Google

 /*
  * drivers/cpufreq/cpufreq_governor.c
  *
  * CPUFREQ governors common code
  *
  * Copyright	(C) 2001 Russell King
  *		(C) 2003 Venkatesh Pallipadi <venkatesh.pallipadi@intel.com>.
  *		(C) 2003 Jun Nakajima <jun.nakajima@intel.com>
  *		(C) 2009 Alexander Clouter <alex@digriz.org.uk>
  *		(c) 2012 Viresh Kumar <viresh.kumar@linaro.org>
  *
  * 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.
  */

 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt

 #include <linux/export.h>
 #include <linux/kernel_stat.h>
 #include <linux/slab.h>

 #include "cpufreq_governor.h"

 static struct attribute_group *get_sysfs_attr(struct dbs_data *dbs_data)
 {
 	if (have_governor_per_policy())
 		return dbs_data->cdata->attr_group_gov_pol;
 	else
 		return dbs_data->cdata->attr_group_gov_sys;
 }

 void dbs_check_cpu(struct dbs_data *dbs_data, int cpu)
 {
 	struct cpu_dbs_common_info *cdbs = dbs_data->cdata->get_cpu_cdbs(cpu);
 	struct od_dbs_tuners *od_tuners = dbs_data->tuners;
 	struct cs_dbs_tuners *cs_tuners = dbs_data->tuners;
 	struct cpufreq_policy *policy;
 	unsigned int max_load = 0;
 	unsigned int ignore_nice;
 	unsigned int j;

 	if (dbs_data->cdata->governor == GOV_ONDEMAND)
 		ignore_nice = od_tuners->ignore_nice_load;
 	else
 		ignore_nice = cs_tuners->ignore_nice_load;

 	policy = cdbs->cur_policy;

 	/* Get Absolute Load */
 	for_each_cpu(j, policy->cpus) {
 		struct cpu_dbs_common_info *j_cdbs;
 		u64 cur_wall_time, cur_idle_time;
 		unsigned int idle_time, wall_time;
 		unsigned int load;
 		int io_busy = 0;

 		j_cdbs = dbs_data->cdata->get_cpu_cdbs(j);

 		/*
 		 * For the purpose of ondemand, waiting for disk IO is
 		 * an indication that you're performance critical, and
 		 * not that the system is actually idle. So do not add
 		 * the iowait time to the cpu idle time.
 		 */
 		if (dbs_data->cdata->governor == GOV_ONDEMAND)
 			io_busy = od_tuners->io_is_busy;
 		cur_idle_time = get_cpu_idle_time(j, &cur_wall_time, io_busy);

 		wall_time = (unsigned int)
 			(cur_wall_time - j_cdbs->prev_cpu_wall);
 		j_cdbs->prev_cpu_wall = cur_wall_time;

 		idle_time = (unsigned int)
 			(cur_idle_time - j_cdbs->prev_cpu_idle);
 		j_cdbs->prev_cpu_idle = cur_idle_time;

 		if (ignore_nice) {
 			u64 cur_nice;
 			unsigned long cur_nice_jiffies;

 			cur_nice = kcpustat_cpu(j).cpustat[CPUTIME_NICE] -
 					 cdbs->prev_cpu_nice;
 			/*
 			 * Assumption: nice time between sampling periods will
 			 * be less than 2^32 jiffies for 32 bit sys
 			 */
 			cur_nice_jiffies = (unsigned long)
 					cputime64_to_jiffies64(cur_nice);

 			cdbs->prev_cpu_nice =
 				kcpustat_cpu(j).cpustat[CPUTIME_NICE];
 			idle_time += jiffies_to_usecs(cur_nice_jiffies);
 		}

 		if (unlikely(!wall_time || wall_time < idle_time))
 			continue;

 		load = 100 * (wall_time - idle_time) / wall_time;

 		if (load > max_load)
 			max_load = load;
 	}

 	dbs_data->cdata->gov_check_cpu(cpu, max_load);
 }
 EXPORT_SYMBOL_GPL(dbs_check_cpu);

 static inline void __gov_queue_work(int cpu, struct dbs_data *dbs_data,
 		unsigned int delay)
 {
 	struct cpu_dbs_common_info *cdbs = dbs_data->cdata->get_cpu_cdbs(cpu);

 	mod_delayed_work_on(cpu, system_wq, &cdbs->work, delay);
 }

 void gov_queue_work(struct dbs_data *dbs_data, struct cpufreq_policy *policy,
 		unsigned int delay, bool all_cpus)
 {
 	int i;

 	mutex_lock(&cpufreq_governor_lock);
 	if (!policy->governor_enabled)
 		goto out_unlock;

 	if (!all_cpus) {
 		/*
 		 * Use raw_smp_processor_id() to avoid preemptible warnings.
 		 * We know that this is only called with all_cpus == false from
 		 * works that have been queued with *_work_on() functions and
 		 * those works are canceled during CPU_DOWN_PREPARE so they
 		 * can't possibly run on any other CPU.
 		 */
 		__gov_queue_work(raw_smp_processor_id(), dbs_data, delay);
 	} else {
 		for_each_cpu(i, policy->cpus)
 			__gov_queue_work(i, dbs_data, delay);
 	}

 out_unlock:
 	mutex_unlock(&cpufreq_governor_lock);
 }
 EXPORT_SYMBOL_GPL(gov_queue_work);

 static inline void gov_cancel_work(struct dbs_data *dbs_data,
 		struct cpufreq_policy *policy)
 {
 	struct cpu_dbs_common_info *cdbs;
 	int i;

 	for_each_cpu(i, policy->cpus) {
 		cdbs = dbs_data->cdata->get_cpu_cdbs(i);
 		cancel_delayed_work_sync(&cdbs->work);
 	}
 }

 /* Will return if we need to evaluate cpu load again or not */
 bool need_load_eval(struct cpu_dbs_common_info *cdbs,
 		unsigned int sampling_rate)
 {
 	if (policy_is_shared(cdbs->cur_policy)) {
 		ktime_t time_now = ktime_get();
 		s64 delta_us = ktime_us_delta(time_now, cdbs->time_stamp);

 		/* Do nothing if we recently have sampled */
 		if (delta_us < (s64)(sampling_rate / 2))
 			return false;
 		else
 			cdbs->time_stamp = time_now;
 	}

 	return true;
 }
 EXPORT_SYMBOL_GPL(need_load_eval);

 static void set_sampling_rate(struct dbs_data *dbs_data,
 		unsigned int sampling_rate)
 {
 	if (dbs_data->cdata->governor == GOV_CONSERVATIVE) {
 		struct cs_dbs_tuners *cs_tuners = dbs_data->tuners;
 		cs_tuners->sampling_rate = sampling_rate;
 	} else {
 		struct od_dbs_tuners *od_tuners = dbs_data->tuners;
 		od_tuners->sampling_rate = sampling_rate;
 	}
 }

 int cpufreq_governor_dbs(struct cpufreq_policy *policy,
 		struct common_dbs_data *cdata, unsigned int event)
 {
 	struct dbs_data *dbs_data;
 	struct od_cpu_dbs_info_s *od_dbs_info = NULL;
 	struct cs_cpu_dbs_info_s *cs_dbs_info = NULL;
 	struct od_ops *od_ops = NULL;
 	struct od_dbs_tuners *od_tuners = NULL;
 	struct cs_dbs_tuners *cs_tuners = NULL;
 	struct cpu_dbs_common_info *cpu_cdbs;
 	unsigned int sampling_rate, latency, ignore_nice, j, cpu = policy->cpu;
 	int io_busy = 0;
 	int rc;

 	if (have_governor_per_policy())
 		dbs_data = policy->governor_data;
 	else
 		dbs_data = cdata->gdbs_data;

 	WARN_ON(!dbs_data && (event != CPUFREQ_GOV_POLICY_INIT));

 	switch (event) {
 	case CPUFREQ_GOV_POLICY_INIT:
 		if (have_governor_per_policy()) {
 			WARN_ON(dbs_data);
 		} else if (dbs_data) {
 			dbs_data->usage_count++;
 			policy->governor_data = dbs_data;
 			return 0;
 		}

 		dbs_data = kzalloc(sizeof(*dbs_data), GFP_KERNEL);
 		if (!dbs_data) {
 			pr_err("%s: POLICY_INIT: kzalloc failed\n", __func__);
 			return -ENOMEM;
 		}

 		dbs_data->cdata = cdata;
 		dbs_data->usage_count = 1;
 		rc = cdata->init(dbs_data);
 		if (rc) {
 			pr_err("%s: POLICY_INIT: init() failed\n", __func__);
 			kfree(dbs_data);
 			return rc;
 		}

 		if (!have_governor_per_policy())
 			WARN_ON(cpufreq_get_global_kobject());

 		rc = sysfs_create_group(get_governor_parent_kobj(policy),
 				get_sysfs_attr(dbs_data));
 		if (rc) {
 			cdata->exit(dbs_data);
 			kfree(dbs_data);
 			return rc;
 		}

 		policy->governor_data = dbs_data;

 		/* policy latency is in ns. Convert it to us first */
 		latency = policy->cpuinfo.transition_latency / 1000;
 		if (latency == 0)
 			latency = 1;

 		/* Bring kernel and HW constraints together */
 		dbs_data->min_sampling_rate = max(dbs_data->min_sampling_rate,
 				MIN_LATENCY_MULTIPLIER * latency);
 		set_sampling_rate(dbs_data, max(dbs_data->min_sampling_rate,
 					latency * LATENCY_MULTIPLIER));

 		if ((cdata->governor == GOV_CONSERVATIVE) &&
 				(!policy->governor->initialized)) {
 			struct cs_ops *cs_ops = dbs_data->cdata->gov_ops;

 			cpufreq_register_notifier(cs_ops->notifier_block,
 					CPUFREQ_TRANSITION_NOTIFIER);
 		}

 		if (!have_governor_per_policy())
 			cdata->gdbs_data = dbs_data;

 		return 0;
 	case CPUFREQ_GOV_POLICY_EXIT:
 		if (!--dbs_data->usage_count) {
 			sysfs_remove_group(get_governor_parent_kobj(policy),
 					get_sysfs_attr(dbs_data));

 			if (!have_governor_per_policy())
 				cpufreq_put_global_kobject();

 			if ((dbs_data->cdata->governor == GOV_CONSERVATIVE) &&
 				(policy->governor->initialized == 1)) {
 				struct cs_ops *cs_ops = dbs_data->cdata->gov_ops;

 				cpufreq_unregister_notifier(cs_ops->notifier_block,
 						CPUFREQ_TRANSITION_NOTIFIER);
 			}

 			cdata->exit(dbs_data);
 			kfree(dbs_data);
 			cdata->gdbs_data = NULL;
 		}

 		policy->governor_data = NULL;
 		return 0;
 	}

 	cpu_cdbs = dbs_data->cdata->get_cpu_cdbs(cpu);

 	if (dbs_data->cdata->governor == GOV_CONSERVATIVE) {
 		cs_tuners = dbs_data->tuners;
 		cs_dbs_info = dbs_data->cdata->get_cpu_dbs_info_s(cpu);
 		sampling_rate = cs_tuners->sampling_rate;
 		ignore_nice = cs_tuners->ignore_nice_load;
 	} else {
 		od_tuners = dbs_data->tuners;
 		od_dbs_info = dbs_data->cdata->get_cpu_dbs_info_s(cpu);
 		sampling_rate = od_tuners->sampling_rate;
 		ignore_nice = od_tuners->ignore_nice_load;
 		od_ops = dbs_data->cdata->gov_ops;
 		io_busy = od_tuners->io_is_busy;
 	}

 	switch (event) {
 	case CPUFREQ_GOV_START:
 		if (!policy->cur)
 			return -EINVAL;

 		mutex_lock(&dbs_data->mutex);

 		for_each_cpu(j, policy->cpus) {
 			struct cpu_dbs_common_info *j_cdbs =
 				dbs_data->cdata->get_cpu_cdbs(j);

 			j_cdbs->cpu = j;
 			j_cdbs->cur_policy = policy;
 			j_cdbs->prev_cpu_idle = get_cpu_idle_time(j,
 					       &j_cdbs->prev_cpu_wall, io_busy);
 			if (ignore_nice)
 				j_cdbs->prev_cpu_nice =
 					kcpustat_cpu(j).cpustat[CPUTIME_NICE];

 			mutex_init(&j_cdbs->timer_mutex);
 			INIT_DEFERRABLE_WORK(&j_cdbs->work,
 					     dbs_data->cdata->gov_dbs_timer);
 		}

 		if (dbs_data->cdata->governor == GOV_CONSERVATIVE) {
 			cs_dbs_info->down_skip = 0;
 			cs_dbs_info->enable = 1;
 			cs_dbs_info->requested_freq = policy->cur;
 		} else {
 			od_dbs_info->rate_mult = 1;
 			od_dbs_info->sample_type = OD_NORMAL_SAMPLE;
 			od_ops->powersave_bias_init_cpu(cpu);
 		}

 		mutex_unlock(&dbs_data->mutex);

 		/* Initiate timer time stamp */
 		cpu_cdbs->time_stamp = ktime_get();

 		gov_queue_work(dbs_data, policy,
 				delay_for_sampling_rate(sampling_rate), true);
 		break;

 	case CPUFREQ_GOV_STOP:
 		if (dbs_data->cdata->governor == GOV_CONSERVATIVE)
 			cs_dbs_info->enable = 0;

 		gov_cancel_work(dbs_data, policy);

 		mutex_lock(&dbs_data->mutex);
 		mutex_destroy(&cpu_cdbs->timer_mutex);
 		cpu_cdbs->cur_policy = NULL;

 		mutex_unlock(&dbs_data->mutex);

 		break;

 	case CPUFREQ_GOV_LIMITS:
 		mutex_lock(&cpu_cdbs->timer_mutex);
 		if (policy->max < cpu_cdbs->cur_policy->cur)
 			__cpufreq_driver_target(cpu_cdbs->cur_policy,
 					policy->max, CPUFREQ_RELATION_H);
 		else if (policy->min > cpu_cdbs->cur_policy->cur)
 			__cpufreq_driver_target(cpu_cdbs->cur_policy,
 					policy->min, CPUFREQ_RELATION_L);
 		dbs_check_cpu(dbs_data, cpu);
 		mutex_unlock(&cpu_cdbs->timer_mutex);
 		break;
 	}
 	return 0;
 }
 EXPORT_SYMBOL_GPL(cpufreq_governor_dbs);
	/*
	* drivers/cpufreq/cpufreq_governor.c
	*
	* CPUFREQ governors common code
	*
	* Copyright (C) 2001 Russell King
	* (C) 2003 Venkatesh Pallipadi <venkatesh.pallipadi@intel.com>.
	* (C) 2003 Jun Nakajima <jun.nakajima@intel.com>
	* (C) 2009 Alexander Clouter <alex@digriz.org.uk>
	* (c) 2012 Viresh Kumar <viresh.kumar@linaro.org>
	*
	* 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.
	*/

	#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt

	#include <linux/export.h>
	#include <linux/kernel_stat.h>
	#include <linux/slab.h>

	#include "cpufreq_governor.h"

	static struct attribute_group get_sysfs_attr(struct dbs_data dbs_data)
	{
	if (have_governor_per_policy())
	return dbs_data->cdata->attr_group_gov_pol;
	else
	return dbs_data->cdata->attr_group_gov_sys;
	}

	void dbs_check_cpu(struct dbs_data *dbs_data, int cpu)
	{
	struct cpu_dbs_common_info *cdbs = dbs_data->cdata->get_cpu_cdbs(cpu);
	struct od_dbs_tuners *od_tuners = dbs_data->tuners;
	struct cs_dbs_tuners *cs_tuners = dbs_data->tuners;
	struct cpufreq_policy *policy;
	unsigned int max_load = 0;
	unsigned int ignore_nice;
	unsigned int j;

	if (dbs_data->cdata->governor == GOV_ONDEMAND)
	ignore_nice = od_tuners->ignore_nice_load;
	else
	ignore_nice = cs_tuners->ignore_nice_load;

	policy = cdbs->cur_policy;

	/* Get Absolute Load */
	for_each_cpu(j, policy->cpus) {
	struct cpu_dbs_common_info *j_cdbs;
	u64 cur_wall_time, cur_idle_time;
	unsigned int idle_time, wall_time;
	unsigned int load;
	int io_busy = 0;

	j_cdbs = dbs_data->cdata->get_cpu_cdbs(j);

	/*
	* For the purpose of ondemand, waiting for disk IO is
	* an indication that you're performance critical, and
	* not that the system is actually idle. So do not add
	* the iowait time to the cpu idle time.
	*/
	if (dbs_data->cdata->governor == GOV_ONDEMAND)
	io_busy = od_tuners->io_is_busy;
	cur_idle_time = get_cpu_idle_time(j, &cur_wall_time, io_busy);

	wall_time = (unsigned int)
	(cur_wall_time - j_cdbs->prev_cpu_wall);
	j_cdbs->prev_cpu_wall = cur_wall_time;

	idle_time = (unsigned int)
	(cur_idle_time - j_cdbs->prev_cpu_idle);
	j_cdbs->prev_cpu_idle = cur_idle_time;

	if (ignore_nice) {
	u64 cur_nice;
	unsigned long cur_nice_jiffies;

	cur_nice = kcpustat_cpu(j).cpustat[CPUTIME_NICE] -
	cdbs->prev_cpu_nice;
	/*
	* Assumption: nice time between sampling periods will
	* be less than 2^32 jiffies for 32 bit sys
	*/
	cur_nice_jiffies = (unsigned long)
	cputime64_to_jiffies64(cur_nice);

	cdbs->prev_cpu_nice =
	kcpustat_cpu(j).cpustat[CPUTIME_NICE];
	idle_time += jiffies_to_usecs(cur_nice_jiffies);
	}

	if (unlikely(!wall_time \|\| wall_time < idle_time))
	continue;

	load = 100 * (wall_time - idle_time) / wall_time;

	if (load > max_load)
	max_load = load;
	}

	dbs_data->cdata->gov_check_cpu(cpu, max_load);
	}
	EXPORT_SYMBOL_GPL(dbs_check_cpu);

	static inline void __gov_queue_work(int cpu, struct dbs_data *dbs_data,
	unsigned int delay)
	{
	struct cpu_dbs_common_info *cdbs = dbs_data->cdata->get_cpu_cdbs(cpu);

	mod_delayed_work_on(cpu, system_wq, &cdbs->work, delay);
	}

	void gov_queue_work(struct dbs_data dbs_data, struct cpufreq_policy policy,
	unsigned int delay, bool all_cpus)
	{
	int i;

	mutex_lock(&cpufreq_governor_lock);
	if (!policy->governor_enabled)
	goto out_unlock;

	if (!all_cpus) {
	/*
	* Use raw_smp_processor_id() to avoid preemptible warnings.
	* We know that this is only called with all_cpus == false from
	* works that have been queued with *_work_on() functions and
	* those works are canceled during CPU_DOWN_PREPARE so they
	* can't possibly run on any other CPU.
	*/
	__gov_queue_work(raw_smp_processor_id(), dbs_data, delay);
	} else {
	for_each_cpu(i, policy->cpus)
	__gov_queue_work(i, dbs_data, delay);
	}

	out_unlock:
	mutex_unlock(&cpufreq_governor_lock);
	}
	EXPORT_SYMBOL_GPL(gov_queue_work);

	static inline void gov_cancel_work(struct dbs_data *dbs_data,
	struct cpufreq_policy *policy)
	{
	struct cpu_dbs_common_info *cdbs;
	int i;

	for_each_cpu(i, policy->cpus) {
	cdbs = dbs_data->cdata->get_cpu_cdbs(i);
	cancel_delayed_work_sync(&cdbs->work);
	}
	}

	/* Will return if we need to evaluate cpu load again or not */
	bool need_load_eval(struct cpu_dbs_common_info *cdbs,
	unsigned int sampling_rate)
	{
	if (policy_is_shared(cdbs->cur_policy)) {
	ktime_t time_now = ktime_get();
	s64 delta_us = ktime_us_delta(time_now, cdbs->time_stamp);

	/* Do nothing if we recently have sampled */
	if (delta_us < (s64)(sampling_rate / 2))
	return false;
	else
	cdbs->time_stamp = time_now;
	}

	return true;
	}
	EXPORT_SYMBOL_GPL(need_load_eval);

	static void set_sampling_rate(struct dbs_data *dbs_data,
	unsigned int sampling_rate)
	{
	if (dbs_data->cdata->governor == GOV_CONSERVATIVE) {
	struct cs_dbs_tuners *cs_tuners = dbs_data->tuners;
	cs_tuners->sampling_rate = sampling_rate;
	} else {
	struct od_dbs_tuners *od_tuners = dbs_data->tuners;
	od_tuners->sampling_rate = sampling_rate;
	}
	}

	int cpufreq_governor_dbs(struct cpufreq_policy *policy,
	struct common_dbs_data *cdata, unsigned int event)
	{
	struct dbs_data *dbs_data;
	struct od_cpu_dbs_info_s *od_dbs_info = NULL;
	struct cs_cpu_dbs_info_s *cs_dbs_info = NULL;
	struct od_ops *od_ops = NULL;
	struct od_dbs_tuners *od_tuners = NULL;
	struct cs_dbs_tuners *cs_tuners = NULL;
	struct cpu_dbs_common_info *cpu_cdbs;
	unsigned int sampling_rate, latency, ignore_nice, j, cpu = policy->cpu;
	int io_busy = 0;
	int rc;

	if (have_governor_per_policy())
	dbs_data = policy->governor_data;
	else
	dbs_data = cdata->gdbs_data;

	WARN_ON(!dbs_data && (event != CPUFREQ_GOV_POLICY_INIT));

	switch (event) {
	case CPUFREQ_GOV_POLICY_INIT:
	if (have_governor_per_policy()) {
	WARN_ON(dbs_data);
	} else if (dbs_data) {
	dbs_data->usage_count++;
	policy->governor_data = dbs_data;
	return 0;
	}

	dbs_data = kzalloc(sizeof(*dbs_data), GFP_KERNEL);
	if (!dbs_data) {
	pr_err("%s: POLICY_INIT: kzalloc failed\n", __func__);
	return -ENOMEM;
	}

	dbs_data->cdata = cdata;
	dbs_data->usage_count = 1;
	rc = cdata->init(dbs_data);
	if (rc) {
	pr_err("%s: POLICY_INIT: init() failed\n", __func__);
	kfree(dbs_data);
	return rc;
	}

	if (!have_governor_per_policy())
	WARN_ON(cpufreq_get_global_kobject());

	rc = sysfs_create_group(get_governor_parent_kobj(policy),
	get_sysfs_attr(dbs_data));
	if (rc) {
	cdata->exit(dbs_data);
	kfree(dbs_data);
	return rc;
	}

	policy->governor_data = dbs_data;

	/* policy latency is in ns. Convert it to us first */
	latency = policy->cpuinfo.transition_latency / 1000;
	if (latency == 0)
	latency = 1;

	/* Bring kernel and HW constraints together */
	dbs_data->min_sampling_rate = max(dbs_data->min_sampling_rate,
	MIN_LATENCY_MULTIPLIER * latency);
	set_sampling_rate(dbs_data, max(dbs_data->min_sampling_rate,
	latency * LATENCY_MULTIPLIER));

	if ((cdata->governor == GOV_CONSERVATIVE) &&
	(!policy->governor->initialized)) {
	struct cs_ops *cs_ops = dbs_data->cdata->gov_ops;

	cpufreq_register_notifier(cs_ops->notifier_block,
	CPUFREQ_TRANSITION_NOTIFIER);
	}

	if (!have_governor_per_policy())
	cdata->gdbs_data = dbs_data;

	return 0;
	case CPUFREQ_GOV_POLICY_EXIT:
	if (!--dbs_data->usage_count) {
	sysfs_remove_group(get_governor_parent_kobj(policy),
	get_sysfs_attr(dbs_data));

	if (!have_governor_per_policy())
	cpufreq_put_global_kobject();

	if ((dbs_data->cdata->governor == GOV_CONSERVATIVE) &&
	(policy->governor->initialized == 1)) {
	struct cs_ops *cs_ops = dbs_data->cdata->gov_ops;

	cpufreq_unregister_notifier(cs_ops->notifier_block,
	CPUFREQ_TRANSITION_NOTIFIER);
	}

	cdata->exit(dbs_data);
	kfree(dbs_data);
	cdata->gdbs_data = NULL;
	}

	policy->governor_data = NULL;
	return 0;
	}

	cpu_cdbs = dbs_data->cdata->get_cpu_cdbs(cpu);

	if (dbs_data->cdata->governor == GOV_CONSERVATIVE) {
	cs_tuners = dbs_data->tuners;
	cs_dbs_info = dbs_data->cdata->get_cpu_dbs_info_s(cpu);
	sampling_rate = cs_tuners->sampling_rate;
	ignore_nice = cs_tuners->ignore_nice_load;
	} else {
	od_tuners = dbs_data->tuners;
	od_dbs_info = dbs_data->cdata->get_cpu_dbs_info_s(cpu);
	sampling_rate = od_tuners->sampling_rate;
	ignore_nice = od_tuners->ignore_nice_load;
	od_ops = dbs_data->cdata->gov_ops;
	io_busy = od_tuners->io_is_busy;
	}

	switch (event) {
	case CPUFREQ_GOV_START:
	if (!policy->cur)
	return -EINVAL;

	mutex_lock(&dbs_data->mutex);

	for_each_cpu(j, policy->cpus) {
	struct cpu_dbs_common_info *j_cdbs =
	dbs_data->cdata->get_cpu_cdbs(j);

	j_cdbs->cpu = j;
	j_cdbs->cur_policy = policy;
	j_cdbs->prev_cpu_idle = get_cpu_idle_time(j,
	&j_cdbs->prev_cpu_wall, io_busy);
	if (ignore_nice)
	j_cdbs->prev_cpu_nice =
	kcpustat_cpu(j).cpustat[CPUTIME_NICE];

	mutex_init(&j_cdbs->timer_mutex);
	INIT_DEFERRABLE_WORK(&j_cdbs->work,
	dbs_data->cdata->gov_dbs_timer);
	}

	if (dbs_data->cdata->governor == GOV_CONSERVATIVE) {
	cs_dbs_info->down_skip = 0;
	cs_dbs_info->enable = 1;
	cs_dbs_info->requested_freq = policy->cur;
	} else {
	od_dbs_info->rate_mult = 1;
	od_dbs_info->sample_type = OD_NORMAL_SAMPLE;
	od_ops->powersave_bias_init_cpu(cpu);
	}

	mutex_unlock(&dbs_data->mutex);

	/* Initiate timer time stamp */
	cpu_cdbs->time_stamp = ktime_get();

	gov_queue_work(dbs_data, policy,
	delay_for_sampling_rate(sampling_rate), true);
	break;

	case CPUFREQ_GOV_STOP:
	if (dbs_data->cdata->governor == GOV_CONSERVATIVE)
	cs_dbs_info->enable = 0;

	gov_cancel_work(dbs_data, policy);

	mutex_lock(&dbs_data->mutex);
	mutex_destroy(&cpu_cdbs->timer_mutex);
	cpu_cdbs->cur_policy = NULL;

	mutex_unlock(&dbs_data->mutex);

	break;

	case CPUFREQ_GOV_LIMITS:
	mutex_lock(&cpu_cdbs->timer_mutex);
	if (policy->max < cpu_cdbs->cur_policy->cur)
	__cpufreq_driver_target(cpu_cdbs->cur_policy,
	policy->max, CPUFREQ_RELATION_H);
	else if (policy->min > cpu_cdbs->cur_policy->cur)
	__cpufreq_driver_target(cpu_cdbs->cur_policy,
	policy->min, CPUFREQ_RELATION_L);
	dbs_check_cpu(dbs_data, cpu);
	mutex_unlock(&cpu_cdbs->timer_mutex);
	break;
	}
	return 0;
	}
	EXPORT_SYMBOL_GPL(cpufreq_governor_dbs);