cpufreq_conservative.c 10.8 KB
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/*
 *  drivers/cpufreq/cpufreq_conservative.c
 *
 *  Copyright (C)  2001 Russell King
 *            (C)  2003 Venkatesh Pallipadi <venkatesh.pallipadi@intel.com>.
 *                      Jun Nakajima <jun.nakajima@intel.com>
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 *            (C)  2009 Alexander Clouter <alex@digriz.org.uk>
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 *
 * 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.
 */

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#include <linux/slab.h>
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#include "cpufreq_governor.h"
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/* Conservative governor macros */
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#define DEF_FREQUENCY_UP_THRESHOLD		(80)
#define DEF_FREQUENCY_DOWN_THRESHOLD		(20)
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#define DEF_FREQUENCY_STEP			(5)
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#define DEF_SAMPLING_DOWN_FACTOR		(1)
#define MAX_SAMPLING_DOWN_FACTOR		(10)
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static DEFINE_PER_CPU(struct cs_cpu_dbs_info_s, cs_cpu_dbs_info);
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static int cs_cpufreq_governor_dbs(struct cpufreq_policy *policy,
				   unsigned int event);

#ifndef CONFIG_CPU_FREQ_DEFAULT_GOV_CONSERVATIVE
static
#endif
struct cpufreq_governor cpufreq_gov_conservative = {
	.name			= "conservative",
	.governor		= cs_cpufreq_governor_dbs,
	.max_transition_latency	= TRANSITION_LATENCY_LIMIT,
	.owner			= THIS_MODULE,
};

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static inline unsigned int get_freq_target(struct cs_dbs_tuners *cs_tuners,
					   struct cpufreq_policy *policy)
{
	unsigned int freq_target = (cs_tuners->freq_step * policy->max) / 100;

	/* max freq cannot be less than 100. But who knows... */
	if (unlikely(freq_target == 0))
		freq_target = DEF_FREQUENCY_STEP;

	return freq_target;
}

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/*
 * Every sampling_rate, we check, if current idle time is less than 20%
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 * (default), then we try to increase frequency. Every sampling_rate *
 * sampling_down_factor, we check, if current idle time is more than 80%
 * (default), then we try to decrease frequency
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 *
 * Any frequency increase takes it to the maximum frequency. Frequency reduction
 * happens at minimum steps of 5% (default) of maximum frequency
 */
static void cs_check_cpu(int cpu, unsigned int load)
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{
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	struct cs_cpu_dbs_info_s *dbs_info = &per_cpu(cs_cpu_dbs_info, cpu);
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	struct cpufreq_policy *policy = dbs_info->cdbs.shared->policy;
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	struct dbs_data *dbs_data = policy->governor_data;
	struct cs_dbs_tuners *cs_tuners = dbs_data->tuners;
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	/*
	 * break out if we 'cannot' reduce the speed as the user might
	 * want freq_step to be zero
	 */
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	if (cs_tuners->freq_step == 0)
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		return;

	/* Check for frequency increase */
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	if (load > cs_tuners->up_threshold) {
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		dbs_info->down_skip = 0;

		/* if we are already at full speed then break out early */
		if (dbs_info->requested_freq == policy->max)
			return;

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		dbs_info->requested_freq += get_freq_target(cs_tuners, policy);
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		if (dbs_info->requested_freq > policy->max)
			dbs_info->requested_freq = policy->max;

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		__cpufreq_driver_target(policy, dbs_info->requested_freq,
			CPUFREQ_RELATION_H);
		return;
	}

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	/* if sampling_down_factor is active break out early */
	if (++dbs_info->down_skip < cs_tuners->sampling_down_factor)
		return;
	dbs_info->down_skip = 0;

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	/* Check for frequency decrease */
	if (load < cs_tuners->down_threshold) {
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		unsigned int freq_target;
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		/*
		 * if we cannot reduce the frequency anymore, break out early
		 */
		if (policy->cur == policy->min)
			return;

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		freq_target = get_freq_target(cs_tuners, policy);
		if (dbs_info->requested_freq > freq_target)
			dbs_info->requested_freq -= freq_target;
		else
			dbs_info->requested_freq = policy->min;
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		__cpufreq_driver_target(policy, dbs_info->requested_freq,
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				CPUFREQ_RELATION_L);
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		return;
	}
}

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static unsigned int cs_dbs_timer(struct cpufreq_policy *policy, bool modify_all)
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{
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	struct dbs_data *dbs_data = policy->governor_data;
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	struct cs_dbs_tuners *cs_tuners = dbs_data->tuners;
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	if (modify_all)
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		dbs_check_cpu(dbs_data, policy->cpu);
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	return delay_for_sampling_rate(cs_tuners->sampling_rate);
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}

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static int dbs_cpufreq_notifier(struct notifier_block *nb, unsigned long val,
		void *data)
{
	struct cpufreq_freqs *freq = data;
	struct cs_cpu_dbs_info_s *dbs_info =
					&per_cpu(cs_cpu_dbs_info, freq->cpu);
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	struct cpufreq_policy *policy = cpufreq_cpu_get_raw(freq->cpu);
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	if (!policy)
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		return 0;

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	/* policy isn't governed by conservative governor */
	if (policy->governor != &cpufreq_gov_conservative)
		return 0;
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	/*
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	 * we only care if our internally tracked freq moves outside the 'valid'
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	 * ranges of frequency available to us otherwise we do not change it
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	*/
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	if (dbs_info->requested_freq > policy->max
			|| dbs_info->requested_freq < policy->min)
		dbs_info->requested_freq = freq->new;
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	return 0;
}

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static struct notifier_block cs_cpufreq_notifier_block = {
	.notifier_call = dbs_cpufreq_notifier,
};

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/************************** sysfs interface ************************/
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static struct common_dbs_data cs_dbs_cdata;
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static ssize_t store_sampling_down_factor(struct dbs_data *dbs_data,
		const char *buf, size_t count)
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{
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	struct cs_dbs_tuners *cs_tuners = dbs_data->tuners;
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	unsigned int input;
	int ret;
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	ret = sscanf(buf, "%u", &input);
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	if (ret != 1 || input > MAX_SAMPLING_DOWN_FACTOR || input < 1)
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		return -EINVAL;

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	cs_tuners->sampling_down_factor = input;
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	return count;
}

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static ssize_t store_sampling_rate(struct dbs_data *dbs_data, const char *buf,
		size_t count)
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{
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	struct cs_dbs_tuners *cs_tuners = dbs_data->tuners;
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	unsigned int input;
	int ret;
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	ret = sscanf(buf, "%u", &input);
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	if (ret != 1)
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		return -EINVAL;
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	cs_tuners->sampling_rate = max(input, dbs_data->min_sampling_rate);
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	return count;
}

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static ssize_t store_up_threshold(struct dbs_data *dbs_data, const char *buf,
		size_t count)
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{
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	struct cs_dbs_tuners *cs_tuners = dbs_data->tuners;
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	unsigned int input;
	int ret;
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	ret = sscanf(buf, "%u", &input);
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	if (ret != 1 || input > 100 || input <= cs_tuners->down_threshold)
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		return -EINVAL;

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	cs_tuners->up_threshold = input;
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	return count;
}

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static ssize_t store_down_threshold(struct dbs_data *dbs_data, const char *buf,
		size_t count)
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{
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	struct cs_dbs_tuners *cs_tuners = dbs_data->tuners;
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	unsigned int input;
	int ret;
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	ret = sscanf(buf, "%u", &input);
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	/* cannot be lower than 11 otherwise freq will not fall */
	if (ret != 1 || input < 11 || input > 100 ||
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			input >= cs_tuners->up_threshold)
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		return -EINVAL;

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	cs_tuners->down_threshold = input;
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	return count;
}

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static ssize_t store_ignore_nice_load(struct dbs_data *dbs_data,
		const char *buf, size_t count)
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{
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	struct cs_dbs_tuners *cs_tuners = dbs_data->tuners;
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	unsigned int input, j;
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	int ret;

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	ret = sscanf(buf, "%u", &input);
	if (ret != 1)
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		return -EINVAL;

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	if (input > 1)
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		input = 1;
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	if (input == cs_tuners->ignore_nice_load) /* nothing to do */
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		return count;
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	cs_tuners->ignore_nice_load = input;
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	/* we need to re-evaluate prev_cpu_idle */
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	for_each_online_cpu(j) {
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		struct cs_cpu_dbs_info_s *dbs_info;
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		dbs_info = &per_cpu(cs_cpu_dbs_info, j);
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		dbs_info->cdbs.prev_cpu_idle = get_cpu_idle_time(j,
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					&dbs_info->cdbs.prev_cpu_wall, 0);
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		if (cs_tuners->ignore_nice_load)
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			dbs_info->cdbs.prev_cpu_nice =
				kcpustat_cpu(j).cpustat[CPUTIME_NICE];
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	}
	return count;
}

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static ssize_t store_freq_step(struct dbs_data *dbs_data, const char *buf,
		size_t count)
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{
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	struct cs_dbs_tuners *cs_tuners = dbs_data->tuners;
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	unsigned int input;
	int ret;
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	ret = sscanf(buf, "%u", &input);
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	if (ret != 1)
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		return -EINVAL;

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	if (input > 100)
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		input = 100;
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	/*
	 * no need to test here if freq_step is zero as the user might actually
	 * want this, they would be crazy though :)
	 */
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	cs_tuners->freq_step = input;
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	return count;
}

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show_store_one(cs, sampling_rate);
show_store_one(cs, sampling_down_factor);
show_store_one(cs, up_threshold);
show_store_one(cs, down_threshold);
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show_store_one(cs, ignore_nice_load);
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show_store_one(cs, freq_step);
declare_show_sampling_rate_min(cs);

gov_sys_pol_attr_rw(sampling_rate);
gov_sys_pol_attr_rw(sampling_down_factor);
gov_sys_pol_attr_rw(up_threshold);
gov_sys_pol_attr_rw(down_threshold);
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gov_sys_pol_attr_rw(ignore_nice_load);
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gov_sys_pol_attr_rw(freq_step);
gov_sys_pol_attr_ro(sampling_rate_min);

static struct attribute *dbs_attributes_gov_sys[] = {
	&sampling_rate_min_gov_sys.attr,
	&sampling_rate_gov_sys.attr,
	&sampling_down_factor_gov_sys.attr,
	&up_threshold_gov_sys.attr,
	&down_threshold_gov_sys.attr,
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	&ignore_nice_load_gov_sys.attr,
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	&freq_step_gov_sys.attr,
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	NULL
};

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static struct attribute_group cs_attr_group_gov_sys = {
	.attrs = dbs_attributes_gov_sys,
	.name = "conservative",
};

static struct attribute *dbs_attributes_gov_pol[] = {
	&sampling_rate_min_gov_pol.attr,
	&sampling_rate_gov_pol.attr,
	&sampling_down_factor_gov_pol.attr,
	&up_threshold_gov_pol.attr,
	&down_threshold_gov_pol.attr,
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	&ignore_nice_load_gov_pol.attr,
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	&freq_step_gov_pol.attr,
	NULL
};

static struct attribute_group cs_attr_group_gov_pol = {
	.attrs = dbs_attributes_gov_pol,
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	.name = "conservative",
};

/************************** sysfs end ************************/

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static int cs_init(struct dbs_data *dbs_data, bool notify)
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{
	struct cs_dbs_tuners *tuners;

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

	tuners->up_threshold = DEF_FREQUENCY_UP_THRESHOLD;
	tuners->down_threshold = DEF_FREQUENCY_DOWN_THRESHOLD;
	tuners->sampling_down_factor = DEF_SAMPLING_DOWN_FACTOR;
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	tuners->ignore_nice_load = 0;
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	tuners->freq_step = DEF_FREQUENCY_STEP;
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	dbs_data->tuners = tuners;
	dbs_data->min_sampling_rate = MIN_SAMPLING_RATE_RATIO *
		jiffies_to_usecs(10);
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	if (notify)
		cpufreq_register_notifier(&cs_cpufreq_notifier_block,
					  CPUFREQ_TRANSITION_NOTIFIER);

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	return 0;
}

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static void cs_exit(struct dbs_data *dbs_data, bool notify)
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{
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	if (notify)
		cpufreq_unregister_notifier(&cs_cpufreq_notifier_block,
					    CPUFREQ_TRANSITION_NOTIFIER);

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	kfree(dbs_data->tuners);
}

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define_get_cpu_dbs_routines(cs_cpu_dbs_info);
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static struct common_dbs_data cs_dbs_cdata = {
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	.governor = GOV_CONSERVATIVE,
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	.attr_group_gov_sys = &cs_attr_group_gov_sys,
	.attr_group_gov_pol = &cs_attr_group_gov_pol,
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	.get_cpu_cdbs = get_cpu_cdbs,
	.get_cpu_dbs_info_s = get_cpu_dbs_info_s,
	.gov_dbs_timer = cs_dbs_timer,
	.gov_check_cpu = cs_check_cpu,
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	.init = cs_init,
	.exit = cs_exit,
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	.mutex = __MUTEX_INITIALIZER(cs_dbs_cdata.mutex),
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};
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static int cs_cpufreq_governor_dbs(struct cpufreq_policy *policy,
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				   unsigned int event)
{
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	return cpufreq_governor_dbs(policy, &cs_dbs_cdata, event);
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}

static int __init cpufreq_gov_dbs_init(void)
{
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	return cpufreq_register_governor(&cpufreq_gov_conservative);
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}

static void __exit cpufreq_gov_dbs_exit(void)
{
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	cpufreq_unregister_governor(&cpufreq_gov_conservative);
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}

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MODULE_AUTHOR("Alexander Clouter <alex@digriz.org.uk>");
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MODULE_DESCRIPTION("'cpufreq_conservative' - A dynamic cpufreq governor for "
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		"Low Latency Frequency Transition capable processors "
		"optimised for use in a battery environment");
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MODULE_LICENSE("GPL");
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#ifdef CONFIG_CPU_FREQ_DEFAULT_GOV_CONSERVATIVE
fs_initcall(cpufreq_gov_dbs_init);
#else
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module_init(cpufreq_gov_dbs_init);
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#endif
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module_exit(cpufreq_gov_dbs_exit);