drivers/cpufreq/cpufreq_ondemand.c - third_party/linux - Git at Google

 // SPDX-License-Identifier: GPL-2.0-only
 /*
  *  drivers/cpufreq/cpufreq_ondemand.c
  *
  *  Copyright (C)  2001 Russell King
  *            (C)  2003 Venkatesh Pallipadi <venkatesh.pallipadi@intel.com>.
  *                      Jun Nakajima <jun.nakajima@intel.com>
  */

 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt

 #include <linux/cpu.h>
 #include <linux/percpu-defs.h>
 #include <linux/slab.h>
 #include <linux/tick.h>
 #include <linux/sched/cpufreq.h>

 #include "cpufreq_ondemand.h"

 /* On-demand governor macros */
 #define DEF_FREQUENCY_UP_THRESHOLD		(80)
 #define DEF_SAMPLING_DOWN_FACTOR		(1)
 #define MAX_SAMPLING_DOWN_FACTOR		(100000)
 #define MICRO_FREQUENCY_UP_THRESHOLD		(95)
 #define MICRO_FREQUENCY_MIN_SAMPLE_RATE		(10000)
 #define MIN_FREQUENCY_UP_THRESHOLD		(1)
 #define MAX_FREQUENCY_UP_THRESHOLD		(100)

 static struct od_ops od_ops;

 static unsigned int default_powersave_bias;

 /*
  * Not all CPUs want IO time to be accounted as busy; this depends on how
  * efficient idling at a higher frequency/voltage is.
  * Pavel Machek says this is not so for various generations of AMD and old
  * Intel systems.
  * Mike Chan (android.com) claims this is also not true for ARM.
  * Because of this, whitelist specific known (series) of CPUs by default, and
  * leave all others up to the user.
  */
 static int should_io_be_busy(void)
 {
 #if defined(CONFIG_X86)
 	/*
 	 * For Intel, Core 2 (model 15) and later have an efficient idle.
 	 */
 	if (boot_cpu_data.x86_vendor == X86_VENDOR_INTEL &&
 			boot_cpu_data.x86 == 6 &&
 			boot_cpu_data.x86_model >= 15)
 		return 1;
 #endif
 	return 0;
 }

 /*
  * Find right freq to be set now with powersave_bias on.
  * Returns the freq_hi to be used right now and will set freq_hi_delay_us,
  * freq_lo, and freq_lo_delay_us in percpu area for averaging freqs.
  */
 static unsigned int generic_powersave_bias_target(struct cpufreq_policy *policy,
 		unsigned int freq_next, unsigned int relation)
 {
 	unsigned int freq_req, freq_reduc, freq_avg;
 	unsigned int freq_hi, freq_lo;
 	unsigned int index;
 	unsigned int delay_hi_us;
 	struct policy_dbs_info *policy_dbs = policy->governor_data;
 	struct od_policy_dbs_info *dbs_info = to_dbs_info(policy_dbs);
 	struct dbs_data *dbs_data = policy_dbs->dbs_data;
 	struct od_dbs_tuners *od_tuners = dbs_data->tuners;
 	struct cpufreq_frequency_table *freq_table = policy->freq_table;

 	if (!freq_table) {
 		dbs_info->freq_lo = 0;
 		dbs_info->freq_lo_delay_us = 0;
 		return freq_next;
 	}

 	index = cpufreq_frequency_table_target(policy, freq_next, relation);
 	freq_req = freq_table[index].frequency;
 	freq_reduc = freq_req * od_tuners->powersave_bias / 1000;
 	freq_avg = freq_req - freq_reduc;

 	/* Find freq bounds for freq_avg in freq_table */
 	index = cpufreq_table_find_index_h(policy, freq_avg);
 	freq_lo = freq_table[index].frequency;
 	index = cpufreq_table_find_index_l(policy, freq_avg);
 	freq_hi = freq_table[index].frequency;

 	/* Find out how long we have to be in hi and lo freqs */
 	if (freq_hi == freq_lo) {
 		dbs_info->freq_lo = 0;
 		dbs_info->freq_lo_delay_us = 0;
 		return freq_lo;
 	}
 	delay_hi_us = (freq_avg - freq_lo) * dbs_data->sampling_rate;
 	delay_hi_us += (freq_hi - freq_lo) / 2;
 	delay_hi_us /= freq_hi - freq_lo;
 	dbs_info->freq_hi_delay_us = delay_hi_us;
 	dbs_info->freq_lo = freq_lo;
 	dbs_info->freq_lo_delay_us = dbs_data->sampling_rate - delay_hi_us;
 	return freq_hi;
 }

 static void ondemand_powersave_bias_init(struct cpufreq_policy *policy)
 {
 	struct od_policy_dbs_info *dbs_info = to_dbs_info(policy->governor_data);

 	dbs_info->freq_lo = 0;
 }

 static void dbs_freq_increase(struct cpufreq_policy *policy, unsigned int freq)
 {
 	struct policy_dbs_info *policy_dbs = policy->governor_data;
 	struct dbs_data *dbs_data = policy_dbs->dbs_data;
 	struct od_dbs_tuners *od_tuners = dbs_data->tuners;

 	if (od_tuners->powersave_bias)
 		freq = od_ops.powersave_bias_target(policy, freq,
 				CPUFREQ_RELATION_H);
 	else if (policy->cur == policy->max)
 		return;

 	__cpufreq_driver_target(policy, freq, od_tuners->powersave_bias ?
 			CPUFREQ_RELATION_L : CPUFREQ_RELATION_H);
 }

 /*
  * Every sampling_rate, we check, if current idle time is less than 20%
  * (default), then we try to increase frequency. Else, we adjust the frequency
  * proportional to load.
  */
 static void od_update(struct cpufreq_policy *policy)
 {
 	struct policy_dbs_info *policy_dbs = policy->governor_data;
 	struct od_policy_dbs_info *dbs_info = to_dbs_info(policy_dbs);
 	struct dbs_data *dbs_data = policy_dbs->dbs_data;
 	struct od_dbs_tuners *od_tuners = dbs_data->tuners;
 	unsigned int load = dbs_update(policy);

 	dbs_info->freq_lo = 0;

 	/* Check for frequency increase */
 	if (load > dbs_data->up_threshold) {
 		/* If switching to max speed, apply sampling_down_factor */
 		if (policy->cur < policy->max)
 			policy_dbs->rate_mult = dbs_data->sampling_down_factor;
 		dbs_freq_increase(policy, policy->max);
 	} else {
 		/* Calculate the next frequency proportional to load */
 		unsigned int freq_next, min_f, max_f;

 		min_f = policy->cpuinfo.min_freq;
 		max_f = policy->cpuinfo.max_freq;
 		freq_next = min_f + load * (max_f - min_f) / 100;

 		/* No longer fully busy, reset rate_mult */
 		policy_dbs->rate_mult = 1;

 		if (od_tuners->powersave_bias)
 			freq_next = od_ops.powersave_bias_target(policy,
 								 freq_next,
 								 CPUFREQ_RELATION_L);

 		__cpufreq_driver_target(policy, freq_next, CPUFREQ_RELATION_C);
 	}
 }

 static unsigned int od_dbs_update(struct cpufreq_policy *policy)
 {
 	struct policy_dbs_info *policy_dbs = policy->governor_data;
 	struct dbs_data *dbs_data = policy_dbs->dbs_data;
 	struct od_policy_dbs_info *dbs_info = to_dbs_info(policy_dbs);
 	int sample_type = dbs_info->sample_type;

 	/* Common NORMAL_SAMPLE setup */
 	dbs_info->sample_type = OD_NORMAL_SAMPLE;
 	/*
 	 * OD_SUB_SAMPLE doesn't make sense if sample_delay_ns is 0, so ignore
 	 * it then.
 	 */
 	if (sample_type == OD_SUB_SAMPLE && policy_dbs->sample_delay_ns > 0) {
 		__cpufreq_driver_target(policy, dbs_info->freq_lo,
 					CPUFREQ_RELATION_H);
 		return dbs_info->freq_lo_delay_us;
 	}

 	od_update(policy);

 	if (dbs_info->freq_lo) {
 		/* Setup SUB_SAMPLE */
 		dbs_info->sample_type = OD_SUB_SAMPLE;
 		return dbs_info->freq_hi_delay_us;
 	}

 	return dbs_data->sampling_rate * policy_dbs->rate_mult;
 }

 /************************** sysfs interface ************************/
 static struct dbs_governor od_dbs_gov;

 static ssize_t store_io_is_busy(struct gov_attr_set *attr_set, const char *buf,
 				size_t count)
 {
 	struct dbs_data *dbs_data = to_dbs_data(attr_set);
 	unsigned int input;
 	int ret;

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

 	/* we need to re-evaluate prev_cpu_idle */
 	gov_update_cpu_data(dbs_data);

 	return count;
 }

 static ssize_t store_up_threshold(struct gov_attr_set *attr_set,
 				  const char *buf, size_t count)
 {
 	struct dbs_data *dbs_data = to_dbs_data(attr_set);
 	unsigned int input;
 	int ret;
 	ret = sscanf(buf, "%u", &input);

 	if (ret != 1 || input > MAX_FREQUENCY_UP_THRESHOLD ||
 			input < MIN_FREQUENCY_UP_THRESHOLD) {
 		return -EINVAL;
 	}

 	dbs_data->up_threshold = input;
 	return count;
 }

 static ssize_t store_sampling_down_factor(struct gov_attr_set *attr_set,
 					  const char *buf, size_t count)
 {
 	struct dbs_data *dbs_data = to_dbs_data(attr_set);
 	struct policy_dbs_info *policy_dbs;
 	unsigned int input;
 	int ret;
 	ret = sscanf(buf, "%u", &input);

 	if (ret != 1 || input > MAX_SAMPLING_DOWN_FACTOR || input < 1)
 		return -EINVAL;

 	dbs_data->sampling_down_factor = input;

 	/* Reset down sampling multiplier in case it was active */
 	list_for_each_entry(policy_dbs, &attr_set->policy_list, list) {
 		/*
 		 * Doing this without locking might lead to using different
 		 * rate_mult values in od_update() and od_dbs_update().
 		 */
 		mutex_lock(&policy_dbs->update_mutex);
 		policy_dbs->rate_mult = 1;
 		mutex_unlock(&policy_dbs->update_mutex);
 	}

 	return count;
 }

 static ssize_t store_ignore_nice_load(struct gov_attr_set *attr_set,
 				      const char *buf, size_t count)
 {
 	struct dbs_data *dbs_data = to_dbs_data(attr_set);
 	unsigned int input;
 	int ret;

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

 	if (input > 1)
 		input = 1;

 	if (input == dbs_data->ignore_nice_load) { /* nothing to do */
 		return count;
 	}
 	dbs_data->ignore_nice_load = input;

 	/* we need to re-evaluate prev_cpu_idle */
 	gov_update_cpu_data(dbs_data);

 	return count;
 }

 static ssize_t store_powersave_bias(struct gov_attr_set *attr_set,
 				    const char *buf, size_t count)
 {
 	struct dbs_data *dbs_data = to_dbs_data(attr_set);
 	struct od_dbs_tuners *od_tuners = dbs_data->tuners;
 	struct policy_dbs_info *policy_dbs;
 	unsigned int input;
 	int ret;
 	ret = sscanf(buf, "%u", &input);

 	if (ret != 1)
 		return -EINVAL;

 	if (input > 1000)
 		input = 1000;

 	od_tuners->powersave_bias = input;

 	list_for_each_entry(policy_dbs, &attr_set->policy_list, list)
 		ondemand_powersave_bias_init(policy_dbs->policy);

 	return count;
 }

 gov_show_one_common(sampling_rate);
 gov_show_one_common(up_threshold);
 gov_show_one_common(sampling_down_factor);
 gov_show_one_common(ignore_nice_load);
 gov_show_one_common(io_is_busy);
 gov_show_one(od, powersave_bias);

 gov_attr_rw(sampling_rate);
 gov_attr_rw(io_is_busy);
 gov_attr_rw(up_threshold);
 gov_attr_rw(sampling_down_factor);
 gov_attr_rw(ignore_nice_load);
 gov_attr_rw(powersave_bias);

 static struct attribute *od_attributes[] = {
 	&sampling_rate.attr,
 	&up_threshold.attr,
 	&sampling_down_factor.attr,
 	&ignore_nice_load.attr,
 	&powersave_bias.attr,
 	&io_is_busy.attr,
 	NULL
 };

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

 static struct policy_dbs_info *od_alloc(void)
 {
 	struct od_policy_dbs_info *dbs_info;

 	dbs_info = kzalloc(sizeof(*dbs_info), GFP_KERNEL);
 	return dbs_info ? &dbs_info->policy_dbs : NULL;
 }

 static void od_free(struct policy_dbs_info *policy_dbs)
 {
 	kfree(to_dbs_info(policy_dbs));
 }

 static int od_init(struct dbs_data *dbs_data)
 {
 	struct od_dbs_tuners *tuners;
 	u64 idle_time;
 	int cpu;

 	tuners = kzalloc(sizeof(*tuners), GFP_KERNEL);
 	if (!tuners)
 		return -ENOMEM;

 	cpu = get_cpu();
 	idle_time = get_cpu_idle_time_us(cpu, NULL);
 	put_cpu();
 	if (idle_time != -1ULL) {
 		/* Idle micro accounting is supported. Use finer thresholds */
 		dbs_data->up_threshold = MICRO_FREQUENCY_UP_THRESHOLD;
 	} else {
 		dbs_data->up_threshold = DEF_FREQUENCY_UP_THRESHOLD;
 	}

 	dbs_data->sampling_down_factor = DEF_SAMPLING_DOWN_FACTOR;
 	dbs_data->ignore_nice_load = 0;
 	tuners->powersave_bias = default_powersave_bias;
 	dbs_data->io_is_busy = should_io_be_busy();

 	dbs_data->tuners = tuners;
 	return 0;
 }

 static void od_exit(struct dbs_data *dbs_data)
 {
 	kfree(dbs_data->tuners);
 }

 static void od_start(struct cpufreq_policy *policy)
 {
 	struct od_policy_dbs_info *dbs_info = to_dbs_info(policy->governor_data);

 	dbs_info->sample_type = OD_NORMAL_SAMPLE;
 	ondemand_powersave_bias_init(policy);
 }

 static struct od_ops od_ops = {
 	.powersave_bias_target = generic_powersave_bias_target,
 };

 static struct dbs_governor od_dbs_gov = {
 	.gov = CPUFREQ_DBS_GOVERNOR_INITIALIZER("ondemand"),
 	.kobj_type = { .default_attrs = od_attributes },
 	.gov_dbs_update = od_dbs_update,
 	.alloc = od_alloc,
 	.free = od_free,
 	.init = od_init,
 	.exit = od_exit,
 	.start = od_start,
 };

 #define CPU_FREQ_GOV_ONDEMAND	(od_dbs_gov.gov)

 static void od_set_powersave_bias(unsigned int powersave_bias)
 {
 	unsigned int cpu;
 	cpumask_t done;

 	default_powersave_bias = powersave_bias;
 	cpumask_clear(&done);

 	cpus_read_lock();
 	for_each_online_cpu(cpu) {
 		struct cpufreq_policy *policy;
 		struct policy_dbs_info *policy_dbs;
 		struct dbs_data *dbs_data;
 		struct od_dbs_tuners *od_tuners;

 		if (cpumask_test_cpu(cpu, &done))
 			continue;

 		policy = cpufreq_cpu_get_raw(cpu);
 		if (!policy || policy->governor != &CPU_FREQ_GOV_ONDEMAND)
 			continue;

 		policy_dbs = policy->governor_data;
 		if (!policy_dbs)
 			continue;

 		cpumask_or(&done, &done, policy->cpus);

 		dbs_data = policy_dbs->dbs_data;
 		od_tuners = dbs_data->tuners;
 		od_tuners->powersave_bias = default_powersave_bias;
 	}
 	cpus_read_unlock();
 }

 void od_register_powersave_bias_handler(unsigned int (*f)
 		(struct cpufreq_policy *, unsigned int, unsigned int),
 		unsigned int powersave_bias)
 {
 	od_ops.powersave_bias_target = f;
 	od_set_powersave_bias(powersave_bias);
 }
 EXPORT_SYMBOL_GPL(od_register_powersave_bias_handler);

 void od_unregister_powersave_bias_handler(void)
 {
 	od_ops.powersave_bias_target = generic_powersave_bias_target;
 	od_set_powersave_bias(0);
 }
 EXPORT_SYMBOL_GPL(od_unregister_powersave_bias_handler);

 MODULE_AUTHOR("Venkatesh Pallipadi <venkatesh.pallipadi@intel.com>");
 MODULE_AUTHOR("Alexey Starikovskiy <alexey.y.starikovskiy@intel.com>");
 MODULE_DESCRIPTION("'cpufreq_ondemand' - A dynamic cpufreq governor for "
 	"Low Latency Frequency Transition capable processors");
 MODULE_LICENSE("GPL");

 #ifdef CONFIG_CPU_FREQ_DEFAULT_GOV_ONDEMAND
 struct cpufreq_governor *cpufreq_default_governor(void)
 {
 	return &CPU_FREQ_GOV_ONDEMAND;
 }
 #endif

 cpufreq_governor_init(CPU_FREQ_GOV_ONDEMAND);
 cpufreq_governor_exit(CPU_FREQ_GOV_ONDEMAND);
	// SPDX-License-Identifier: GPL-2.0-only
	/*
	* drivers/cpufreq/cpufreq_ondemand.c
	*
	* Copyright (C) 2001 Russell King
	* (C) 2003 Venkatesh Pallipadi <venkatesh.pallipadi@intel.com>.
	* Jun Nakajima <jun.nakajima@intel.com>
	*/

	#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt

	#include <linux/cpu.h>
	#include <linux/percpu-defs.h>
	#include <linux/slab.h>
	#include <linux/tick.h>
	#include <linux/sched/cpufreq.h>

	#include "cpufreq_ondemand.h"

	/* On-demand governor macros */
	#define DEF_FREQUENCY_UP_THRESHOLD (80)
	#define DEF_SAMPLING_DOWN_FACTOR (1)
	#define MAX_SAMPLING_DOWN_FACTOR (100000)
	#define MICRO_FREQUENCY_UP_THRESHOLD (95)
	#define MICRO_FREQUENCY_MIN_SAMPLE_RATE (10000)
	#define MIN_FREQUENCY_UP_THRESHOLD (1)
	#define MAX_FREQUENCY_UP_THRESHOLD (100)

	static struct od_ops od_ops;

	static unsigned int default_powersave_bias;

	/*
	* Not all CPUs want IO time to be accounted as busy; this depends on how
	* efficient idling at a higher frequency/voltage is.
	* Pavel Machek says this is not so for various generations of AMD and old
	* Intel systems.
	* Mike Chan (android.com) claims this is also not true for ARM.
	* Because of this, whitelist specific known (series) of CPUs by default, and
	* leave all others up to the user.
	*/
	static int should_io_be_busy(void)
	{
	#if defined(CONFIG_X86)
	/*
	* For Intel, Core 2 (model 15) and later have an efficient idle.
	*/
	if (boot_cpu_data.x86_vendor == X86_VENDOR_INTEL &&
	boot_cpu_data.x86 == 6 &&
	boot_cpu_data.x86_model >= 15)
	return 1;
	#endif
	return 0;
	}

	/*
	* Find right freq to be set now with powersave_bias on.
	* Returns the freq_hi to be used right now and will set freq_hi_delay_us,
	* freq_lo, and freq_lo_delay_us in percpu area for averaging freqs.
	*/
	static unsigned int generic_powersave_bias_target(struct cpufreq_policy *policy,
	unsigned int freq_next, unsigned int relation)
	{
	unsigned int freq_req, freq_reduc, freq_avg;
	unsigned int freq_hi, freq_lo;
	unsigned int index;
	unsigned int delay_hi_us;
	struct policy_dbs_info *policy_dbs = policy->governor_data;
	struct od_policy_dbs_info *dbs_info = to_dbs_info(policy_dbs);
	struct dbs_data *dbs_data = policy_dbs->dbs_data;
	struct od_dbs_tuners *od_tuners = dbs_data->tuners;
	struct cpufreq_frequency_table *freq_table = policy->freq_table;

	if (!freq_table) {
	dbs_info->freq_lo = 0;
	dbs_info->freq_lo_delay_us = 0;
	return freq_next;
	}

	index = cpufreq_frequency_table_target(policy, freq_next, relation);
	freq_req = freq_table[index].frequency;
	freq_reduc = freq_req * od_tuners->powersave_bias / 1000;
	freq_avg = freq_req - freq_reduc;

	/* Find freq bounds for freq_avg in freq_table */
	index = cpufreq_table_find_index_h(policy, freq_avg);
	freq_lo = freq_table[index].frequency;
	index = cpufreq_table_find_index_l(policy, freq_avg);
	freq_hi = freq_table[index].frequency;

	/* Find out how long we have to be in hi and lo freqs */
	if (freq_hi == freq_lo) {
	dbs_info->freq_lo = 0;
	dbs_info->freq_lo_delay_us = 0;
	return freq_lo;
	}
	delay_hi_us = (freq_avg - freq_lo) * dbs_data->sampling_rate;
	delay_hi_us += (freq_hi - freq_lo) / 2;
	delay_hi_us /= freq_hi - freq_lo;
	dbs_info->freq_hi_delay_us = delay_hi_us;
	dbs_info->freq_lo = freq_lo;
	dbs_info->freq_lo_delay_us = dbs_data->sampling_rate - delay_hi_us;
	return freq_hi;
	}

	static void ondemand_powersave_bias_init(struct cpufreq_policy *policy)
	{
	struct od_policy_dbs_info *dbs_info = to_dbs_info(policy->governor_data);

	dbs_info->freq_lo = 0;
	}

	static void dbs_freq_increase(struct cpufreq_policy *policy, unsigned int freq)
	{
	struct policy_dbs_info *policy_dbs = policy->governor_data;
	struct dbs_data *dbs_data = policy_dbs->dbs_data;
	struct od_dbs_tuners *od_tuners = dbs_data->tuners;

	if (od_tuners->powersave_bias)
	freq = od_ops.powersave_bias_target(policy, freq,
	CPUFREQ_RELATION_H);
	else if (policy->cur == policy->max)
	return;

	__cpufreq_driver_target(policy, freq, od_tuners->powersave_bias ?
	CPUFREQ_RELATION_L : CPUFREQ_RELATION_H);
	}

	/*
	* Every sampling_rate, we check, if current idle time is less than 20%
	* (default), then we try to increase frequency. Else, we adjust the frequency
	* proportional to load.
	*/
	static void od_update(struct cpufreq_policy *policy)
	{
	struct policy_dbs_info *policy_dbs = policy->governor_data;
	struct od_policy_dbs_info *dbs_info = to_dbs_info(policy_dbs);
	struct dbs_data *dbs_data = policy_dbs->dbs_data;
	struct od_dbs_tuners *od_tuners = dbs_data->tuners;
	unsigned int load = dbs_update(policy);

	dbs_info->freq_lo = 0;

	/* Check for frequency increase */
	if (load > dbs_data->up_threshold) {
	/* If switching to max speed, apply sampling_down_factor */
	if (policy->cur < policy->max)
	policy_dbs->rate_mult = dbs_data->sampling_down_factor;
	dbs_freq_increase(policy, policy->max);
	} else {
	/* Calculate the next frequency proportional to load */
	unsigned int freq_next, min_f, max_f;

	min_f = policy->cpuinfo.min_freq;
	max_f = policy->cpuinfo.max_freq;
	freq_next = min_f + load * (max_f - min_f) / 100;

	/* No longer fully busy, reset rate_mult */
	policy_dbs->rate_mult = 1;

	if (od_tuners->powersave_bias)
	freq_next = od_ops.powersave_bias_target(policy,
	freq_next,
	CPUFREQ_RELATION_L);

	__cpufreq_driver_target(policy, freq_next, CPUFREQ_RELATION_C);
	}
	}

	static unsigned int od_dbs_update(struct cpufreq_policy *policy)
	{
	struct policy_dbs_info *policy_dbs = policy->governor_data;
	struct dbs_data *dbs_data = policy_dbs->dbs_data;
	struct od_policy_dbs_info *dbs_info = to_dbs_info(policy_dbs);
	int sample_type = dbs_info->sample_type;

	/* Common NORMAL_SAMPLE setup */
	dbs_info->sample_type = OD_NORMAL_SAMPLE;
	/*
	* OD_SUB_SAMPLE doesn't make sense if sample_delay_ns is 0, so ignore
	* it then.
	*/
	if (sample_type == OD_SUB_SAMPLE && policy_dbs->sample_delay_ns > 0) {
	__cpufreq_driver_target(policy, dbs_info->freq_lo,
	CPUFREQ_RELATION_H);
	return dbs_info->freq_lo_delay_us;
	}

	od_update(policy);

	if (dbs_info->freq_lo) {
	/* Setup SUB_SAMPLE */
	dbs_info->sample_type = OD_SUB_SAMPLE;
	return dbs_info->freq_hi_delay_us;
	}

	return dbs_data->sampling_rate * policy_dbs->rate_mult;
	}

	/************************ sysfs interface **********************/
	static struct dbs_governor od_dbs_gov;

	static ssize_t store_io_is_busy(struct gov_attr_set attr_set, const char buf,
	size_t count)
	{
	struct dbs_data *dbs_data = to_dbs_data(attr_set);
	unsigned int input;
	int ret;

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

	/* we need to re-evaluate prev_cpu_idle */
	gov_update_cpu_data(dbs_data);

	return count;
	}

	static ssize_t store_up_threshold(struct gov_attr_set *attr_set,
	const char *buf, size_t count)
	{
	struct dbs_data *dbs_data = to_dbs_data(attr_set);
	unsigned int input;
	int ret;
	ret = sscanf(buf, "%u", &input);

	if (ret != 1 \|\| input > MAX_FREQUENCY_UP_THRESHOLD \|\|
	input < MIN_FREQUENCY_UP_THRESHOLD) {
	return -EINVAL;
	}

	dbs_data->up_threshold = input;
	return count;
	}

	static ssize_t store_sampling_down_factor(struct gov_attr_set *attr_set,
	const char *buf, size_t count)
	{
	struct dbs_data *dbs_data = to_dbs_data(attr_set);
	struct policy_dbs_info *policy_dbs;
	unsigned int input;
	int ret;
	ret = sscanf(buf, "%u", &input);

	if (ret != 1 \|\| input > MAX_SAMPLING_DOWN_FACTOR \|\| input < 1)
	return -EINVAL;

	dbs_data->sampling_down_factor = input;

	/* Reset down sampling multiplier in case it was active */
	list_for_each_entry(policy_dbs, &attr_set->policy_list, list) {
	/*
	* Doing this without locking might lead to using different
	* rate_mult values in od_update() and od_dbs_update().
	*/
	mutex_lock(&policy_dbs->update_mutex);
	policy_dbs->rate_mult = 1;
	mutex_unlock(&policy_dbs->update_mutex);
	}

	return count;
	}

	static ssize_t store_ignore_nice_load(struct gov_attr_set *attr_set,
	const char *buf, size_t count)
	{
	struct dbs_data *dbs_data = to_dbs_data(attr_set);
	unsigned int input;
	int ret;

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

	if (input > 1)
	input = 1;

	if (input == dbs_data->ignore_nice_load) { /* nothing to do */
	return count;
	}
	dbs_data->ignore_nice_load = input;

	/* we need to re-evaluate prev_cpu_idle */
	gov_update_cpu_data(dbs_data);

	return count;
	}

	static ssize_t store_powersave_bias(struct gov_attr_set *attr_set,
	const char *buf, size_t count)
	{
	struct dbs_data *dbs_data = to_dbs_data(attr_set);
	struct od_dbs_tuners *od_tuners = dbs_data->tuners;
	struct policy_dbs_info *policy_dbs;
	unsigned int input;
	int ret;
	ret = sscanf(buf, "%u", &input);

	if (ret != 1)
	return -EINVAL;

	if (input > 1000)
	input = 1000;

	od_tuners->powersave_bias = input;

	list_for_each_entry(policy_dbs, &attr_set->policy_list, list)
	ondemand_powersave_bias_init(policy_dbs->policy);

	return count;
	}

	gov_show_one_common(sampling_rate);
	gov_show_one_common(up_threshold);
	gov_show_one_common(sampling_down_factor);
	gov_show_one_common(ignore_nice_load);
	gov_show_one_common(io_is_busy);
	gov_show_one(od, powersave_bias);

	gov_attr_rw(sampling_rate);
	gov_attr_rw(io_is_busy);
	gov_attr_rw(up_threshold);
	gov_attr_rw(sampling_down_factor);
	gov_attr_rw(ignore_nice_load);
	gov_attr_rw(powersave_bias);

	static struct attribute *od_attributes[] = {
	&sampling_rate.attr,
	&up_threshold.attr,
	&sampling_down_factor.attr,
	&ignore_nice_load.attr,
	&powersave_bias.attr,
	&io_is_busy.attr,
	NULL
	};

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

	static struct policy_dbs_info *od_alloc(void)
	{
	struct od_policy_dbs_info *dbs_info;

	dbs_info = kzalloc(sizeof(*dbs_info), GFP_KERNEL);
	return dbs_info ? &dbs_info->policy_dbs : NULL;
	}

	static void od_free(struct policy_dbs_info *policy_dbs)
	{
	kfree(to_dbs_info(policy_dbs));
	}

	static int od_init(struct dbs_data *dbs_data)
	{
	struct od_dbs_tuners *tuners;
	u64 idle_time;
	int cpu;

	tuners = kzalloc(sizeof(*tuners), GFP_KERNEL);
	if (!tuners)
	return -ENOMEM;

	cpu = get_cpu();
	idle_time = get_cpu_idle_time_us(cpu, NULL);
	put_cpu();
	if (idle_time != -1ULL) {
	/* Idle micro accounting is supported. Use finer thresholds */
	dbs_data->up_threshold = MICRO_FREQUENCY_UP_THRESHOLD;
	} else {
	dbs_data->up_threshold = DEF_FREQUENCY_UP_THRESHOLD;
	}

	dbs_data->sampling_down_factor = DEF_SAMPLING_DOWN_FACTOR;
	dbs_data->ignore_nice_load = 0;
	tuners->powersave_bias = default_powersave_bias;
	dbs_data->io_is_busy = should_io_be_busy();

	dbs_data->tuners = tuners;
	return 0;
	}

	static void od_exit(struct dbs_data *dbs_data)
	{
	kfree(dbs_data->tuners);
	}

	static void od_start(struct cpufreq_policy *policy)
	{
	struct od_policy_dbs_info *dbs_info = to_dbs_info(policy->governor_data);

	dbs_info->sample_type = OD_NORMAL_SAMPLE;
	ondemand_powersave_bias_init(policy);
	}

	static struct od_ops od_ops = {
	.powersave_bias_target = generic_powersave_bias_target,
	};

	static struct dbs_governor od_dbs_gov = {
	.gov = CPUFREQ_DBS_GOVERNOR_INITIALIZER("ondemand"),
	.kobj_type = { .default_attrs = od_attributes },
	.gov_dbs_update = od_dbs_update,
	.alloc = od_alloc,
	.free = od_free,
	.init = od_init,
	.exit = od_exit,
	.start = od_start,
	};

	#define CPU_FREQ_GOV_ONDEMAND (od_dbs_gov.gov)

	static void od_set_powersave_bias(unsigned int powersave_bias)
	{
	unsigned int cpu;
	cpumask_t done;

	default_powersave_bias = powersave_bias;
	cpumask_clear(&done);

	cpus_read_lock();
	for_each_online_cpu(cpu) {
	struct cpufreq_policy *policy;
	struct policy_dbs_info *policy_dbs;
	struct dbs_data *dbs_data;
	struct od_dbs_tuners *od_tuners;

	if (cpumask_test_cpu(cpu, &done))
	continue;

	policy = cpufreq_cpu_get_raw(cpu);
	if (!policy \|\| policy->governor != &CPU_FREQ_GOV_ONDEMAND)
	continue;

	policy_dbs = policy->governor_data;
	if (!policy_dbs)
	continue;

	cpumask_or(&done, &done, policy->cpus);

	dbs_data = policy_dbs->dbs_data;
	od_tuners = dbs_data->tuners;
	od_tuners->powersave_bias = default_powersave_bias;
	}
	cpus_read_unlock();
	}

	void od_register_powersave_bias_handler(unsigned int (*f)
	(struct cpufreq_policy *, unsigned int, unsigned int),
	unsigned int powersave_bias)
	{
	od_ops.powersave_bias_target = f;
	od_set_powersave_bias(powersave_bias);
	}
	EXPORT_SYMBOL_GPL(od_register_powersave_bias_handler);

	void od_unregister_powersave_bias_handler(void)
	{
	od_ops.powersave_bias_target = generic_powersave_bias_target;
	od_set_powersave_bias(0);
	}
	EXPORT_SYMBOL_GPL(od_unregister_powersave_bias_handler);

	MODULE_AUTHOR("Venkatesh Pallipadi <venkatesh.pallipadi@intel.com>");
	MODULE_AUTHOR("Alexey Starikovskiy <alexey.y.starikovskiy@intel.com>");
	MODULE_DESCRIPTION("'cpufreq_ondemand' - A dynamic cpufreq governor for "
	"Low Latency Frequency Transition capable processors");
	MODULE_LICENSE("GPL");

	#ifdef CONFIG_CPU_FREQ_DEFAULT_GOV_ONDEMAND
	struct cpufreq_governor *cpufreq_default_governor(void)
	{
	return &CPU_FREQ_GOV_ONDEMAND;
	}
	#endif

	cpufreq_governor_init(CPU_FREQ_GOV_ONDEMAND);
	cpufreq_governor_exit(CPU_FREQ_GOV_ONDEMAND);