[GitHub/mt8127/android_kernel_alcatel_ttab.git] / drivers / cpufreq / cpufreq_conservative.c

/*
 *  drivers/cpufreq/cpufreq_conservative.c
 *
 *  Copyright (C)  2001 Russell King
 *            (C)  2003 Venkatesh Pallipadi <venkatesh.pallipadi@intel.com>.
 *                      Jun Nakajima <jun.nakajima@intel.com>
 *            (C)  2004 Alexander Clouter <alex-kernel@digriz.org.uk>
 *
 * 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/module.h>
#include <linux/smp.h>
#include <linux/init.h>
#include <linux/interrupt.h>
#include <linux/ctype.h>
#include <linux/cpufreq.h>
#include <linux/sysctl.h>
#include <linux/types.h>
#include <linux/fs.h>
#include <linux/sysfs.h>
#include <linux/sched.h>
#include <linux/kmod.h>
#include <linux/workqueue.h>
#include <linux/jiffies.h>
#include <linux/kernel_stat.h>
#include <linux/percpu.h>

/*
 * dbs is used in this file as a shortform for demandbased switching
 * It helps to keep variable names smaller, simpler
 */

#define DEF_FREQUENCY_UP_THRESHOLD		(80)
#define MIN_FREQUENCY_UP_THRESHOLD		(0)
#define MAX_FREQUENCY_UP_THRESHOLD		(100)

#define DEF_FREQUENCY_DOWN_THRESHOLD		(20)
#define MIN_FREQUENCY_DOWN_THRESHOLD		(0)
#define MAX_FREQUENCY_DOWN_THRESHOLD		(100)

/* 
 * The polling frequency of this governor depends on the capability of 
 * the processor. Default polling frequency is 1000 times the transition
 * latency of the processor. The governor will work on any processor with 
 * transition latency <= 10mS, using appropriate sampling 
 * rate.
 * For CPUs with transition latency > 10mS (mostly drivers with CPUFREQ_ETERNAL)
 * this governor will not work.
 * All times here are in uS.
 */
static unsigned int 				def_sampling_rate;
#define MIN_SAMPLING_RATE			(def_sampling_rate / 2)
#define MAX_SAMPLING_RATE			(500 * def_sampling_rate)
#define DEF_SAMPLING_RATE_LATENCY_MULTIPLIER	(100000)
#define DEF_SAMPLING_DOWN_FACTOR		(5)
#define TRANSITION_LATENCY_LIMIT		(10 * 1000)

static void do_dbs_timer(void *data);

struct cpu_dbs_info_s {
	struct cpufreq_policy 	*cur_policy;
	unsigned int 		prev_cpu_idle_up;
	unsigned int 		prev_cpu_idle_down;
	unsigned int 		enable;
};
static DEFINE_PER_CPU(struct cpu_dbs_info_s, cpu_dbs_info);

static unsigned int dbs_enable;	/* number of CPUs using this policy */

static DECLARE_MUTEX 	(dbs_sem);
static DECLARE_WORK	(dbs_work, do_dbs_timer, NULL);

struct dbs_tuners {
	unsigned int 		sampling_rate;
	unsigned int		sampling_down_factor;
	unsigned int		up_threshold;
	unsigned int		down_threshold;
	unsigned int		ignore_nice;
	unsigned int		freq_step;
};

static struct dbs_tuners dbs_tuners_ins = {
	.up_threshold 		= DEF_FREQUENCY_UP_THRESHOLD,
	.down_threshold 	= DEF_FREQUENCY_DOWN_THRESHOLD,
	.sampling_down_factor 	= DEF_SAMPLING_DOWN_FACTOR,
};

static inline unsigned int get_cpu_idle_time(unsigned int cpu)
{
	return	kstat_cpu(cpu).cpustat.idle +
		kstat_cpu(cpu).cpustat.iowait +
		( dbs_tuners_ins.ignore_nice ?
		  kstat_cpu(cpu).cpustat.nice :
		  0);
}

/************************** sysfs interface ************************/
static ssize_t show_sampling_rate_max(struct cpufreq_policy *policy, char *buf)
{
	return sprintf (buf, "%u\n", MAX_SAMPLING_RATE);
}

static ssize_t show_sampling_rate_min(struct cpufreq_policy *policy, char *buf)
{
	return sprintf (buf, "%u\n", MIN_SAMPLING_RATE);
}

#define define_one_ro(_name) 					\
static struct freq_attr _name =  				\
__ATTR(_name, 0444, show_##_name, NULL)

define_one_ro(sampling_rate_max);
define_one_ro(sampling_rate_min);

/* cpufreq_conservative Governor Tunables */
#define show_one(file_name, object)					\
static ssize_t show_##file_name						\
(struct cpufreq_policy *unused, char *buf)				\
{									\
	return sprintf(buf, "%u\n", dbs_tuners_ins.object);		\
}
show_one(sampling_rate, sampling_rate);
show_one(sampling_down_factor, sampling_down_factor);
show_one(up_threshold, up_threshold);
show_one(down_threshold, down_threshold);
show_one(ignore_nice_load, ignore_nice);
show_one(freq_step, freq_step);

static ssize_t store_sampling_down_factor(struct cpufreq_policy *unused, 
		const char *buf, size_t count)
{
	unsigned int input;
	int ret;
	ret = sscanf (buf, "%u", &input);
	if (ret != 1 )
		return -EINVAL;

	down(&dbs_sem);
	dbs_tuners_ins.sampling_down_factor = input;
	up(&dbs_sem);

	return count;
}

static ssize_t store_sampling_rate(struct cpufreq_policy *unused, 
		const char *buf, size_t count)
{
	unsigned int input;
	int ret;
	ret = sscanf (buf, "%u", &input);

	down(&dbs_sem);
	if (ret != 1 || input > MAX_SAMPLING_RATE || input < MIN_SAMPLING_RATE) {
		up(&dbs_sem);
		return -EINVAL;
	}

	dbs_tuners_ins.sampling_rate = input;
	up(&dbs_sem);

	return count;
}

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

	down(&dbs_sem);
	if (ret != 1 || input > MAX_FREQUENCY_UP_THRESHOLD || 
			input < MIN_FREQUENCY_UP_THRESHOLD ||
			input <= dbs_tuners_ins.down_threshold) {
		up(&dbs_sem);
		return -EINVAL;
	}

	dbs_tuners_ins.up_threshold = input;
	up(&dbs_sem);

	return count;
}

static ssize_t store_down_threshold(struct cpufreq_policy *unused, 
		const char *buf, size_t count)
{
	unsigned int input;
	int ret;
	ret = sscanf (buf, "%u", &input);

	down(&dbs_sem);
	if (ret != 1 || input > MAX_FREQUENCY_DOWN_THRESHOLD || 
			input < MIN_FREQUENCY_DOWN_THRESHOLD ||
			input >= dbs_tuners_ins.up_threshold) {
		up(&dbs_sem);
		return -EINVAL;
	}

	dbs_tuners_ins.down_threshold = input;
	up(&dbs_sem);

	return count;
}

static ssize_t store_ignore_nice_load(struct cpufreq_policy *policy,
		const char *buf, size_t count)
{
	unsigned int input;
	int ret;

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

	if ( input > 1 )
		input = 1;
	
	down(&dbs_sem);
	if ( input == dbs_tuners_ins.ignore_nice ) { /* nothing to do */
		up(&dbs_sem);
		return count;
	}
	dbs_tuners_ins.ignore_nice = input;

	/* we need to re-evaluate prev_cpu_idle_up and prev_cpu_idle_down */
	for_each_online_cpu(j) {
		struct cpu_dbs_info_s *j_dbs_info;
		j_dbs_info = &per_cpu(cpu_dbs_info, j);
		j_dbs_info->prev_cpu_idle_up = get_cpu_idle_time(j);
		j_dbs_info->prev_cpu_idle_down = j_dbs_info->prev_cpu_idle_up;
	}
	up(&dbs_sem);

	return count;
}

static ssize_t store_freq_step(struct cpufreq_policy *policy,
		const char *buf, size_t count)
{
	unsigned int input;
	int ret;

	ret = sscanf (buf, "%u", &input);

	if ( ret != 1 )
		return -EINVAL;

	if ( input > 100 )
		input = 100;
	
	/* no need to test here if freq_step is zero as the user might actually
	 * want this, they would be crazy though :) */
	down(&dbs_sem);
	dbs_tuners_ins.freq_step = input;
	up(&dbs_sem);

	return count;
}

#define define_one_rw(_name) \
static struct freq_attr _name = \
__ATTR(_name, 0644, show_##_name, store_##_name)

define_one_rw(sampling_rate);
define_one_rw(sampling_down_factor);
define_one_rw(up_threshold);
define_one_rw(down_threshold);
define_one_rw(ignore_nice_load);
define_one_rw(freq_step);

static struct attribute * dbs_attributes[] = {
	&sampling_rate_max.attr,
	&sampling_rate_min.attr,
	&sampling_rate.attr,
	&sampling_down_factor.attr,
	&up_threshold.attr,
	&down_threshold.attr,
	&ignore_nice_load.attr,
	&freq_step.attr,
	NULL
};

static struct attribute_group dbs_attr_group = {
	.attrs = dbs_attributes,
	.name = "conservative",
};

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

static void dbs_check_cpu(int cpu)
{
	unsigned int idle_ticks, up_idle_ticks, down_idle_ticks;
	unsigned int freq_step;
	unsigned int freq_down_sampling_rate;
	static int down_skip[NR_CPUS];
	static int requested_freq[NR_CPUS];
	static unsigned short init_flag = 0;
	struct cpu_dbs_info_s *this_dbs_info;
	struct cpu_dbs_info_s *dbs_info;

	struct cpufreq_policy *policy;
	unsigned int j;

	this_dbs_info = &per_cpu(cpu_dbs_info, cpu);
	if (!this_dbs_info->enable)
		return;

	policy = this_dbs_info->cur_policy;

	if ( init_flag == 0 ) {
		for_each_online_cpu(j) {
			dbs_info = &per_cpu(cpu_dbs_info, j);
			requested_freq[j] = dbs_info->cur_policy->cur;
		}
		init_flag = 1;
	}
	
	/* 
	 * The default safe range is 20% to 80% 
	 * Every sampling_rate, we check
	 * 	- If current idle time is less than 20%, then we try to 
	 * 	  increase frequency
	 * Every sampling_rate*sampling_down_factor, we check
	 * 	- If current idle time is more than 80%, then we try to
	 * 	  decrease frequency
	 *
	 * Any frequency increase takes it to the maximum frequency. 
	 * Frequency reduction happens at minimum steps of 
	 * 5% (default) of max_frequency 
	 */

	/* Check for frequency increase */

	idle_ticks = UINT_MAX;
	for_each_cpu_mask(j, policy->cpus) {
		unsigned int tmp_idle_ticks, total_idle_ticks;
		struct cpu_dbs_info_s *j_dbs_info;

		j_dbs_info = &per_cpu(cpu_dbs_info, j);
		/* Check for frequency increase */
		total_idle_ticks = get_cpu_idle_time(j);
		tmp_idle_ticks = total_idle_ticks -
			j_dbs_info->prev_cpu_idle_up;
		j_dbs_info->prev_cpu_idle_up = total_idle_ticks;

		if (tmp_idle_ticks < idle_ticks)
			idle_ticks = tmp_idle_ticks;
	}

	/* Scale idle ticks by 100 and compare with up and down ticks */
	idle_ticks *= 100;
	up_idle_ticks = (100 - dbs_tuners_ins.up_threshold) *
		usecs_to_jiffies(dbs_tuners_ins.sampling_rate);

	if (idle_ticks < up_idle_ticks) {
		down_skip[cpu] = 0;
		for_each_cpu_mask(j, policy->cpus) {
			struct cpu_dbs_info_s *j_dbs_info;

			j_dbs_info = &per_cpu(cpu_dbs_info, j);
			j_dbs_info->prev_cpu_idle_down = 
					j_dbs_info->prev_cpu_idle_up;
		}
		/* if we are already at full speed then break out early */
		if (requested_freq[cpu] == policy->max)
			return;
		
		freq_step = (dbs_tuners_ins.freq_step * policy->max) / 100;

		/* max freq cannot be less than 100. But who knows.... */
		if (unlikely(freq_step == 0))
			freq_step = 5;
		
		requested_freq[cpu] += freq_step;
		if (requested_freq[cpu] > policy->max)
			requested_freq[cpu] = policy->max;

		__cpufreq_driver_target(policy, requested_freq[cpu], 
			CPUFREQ_RELATION_H);
		return;
	}

	/* Check for frequency decrease */
	down_skip[cpu]++;
	if (down_skip[cpu] < dbs_tuners_ins.sampling_down_factor)
		return;

	idle_ticks = UINT_MAX;
	for_each_cpu_mask(j, policy->cpus) {
		unsigned int tmp_idle_ticks, total_idle_ticks;
		struct cpu_dbs_info_s *j_dbs_info;

		j_dbs_info = &per_cpu(cpu_dbs_info, j);
		total_idle_ticks = j_dbs_info->prev_cpu_idle_up;
		tmp_idle_ticks = total_idle_ticks -
			j_dbs_info->prev_cpu_idle_down;
		j_dbs_info->prev_cpu_idle_down = total_idle_ticks;

		if (tmp_idle_ticks < idle_ticks)
			idle_ticks = tmp_idle_ticks;
	}

	/* Scale idle ticks by 100 and compare with up and down ticks */
	idle_ticks *= 100;
	down_skip[cpu] = 0;

	freq_down_sampling_rate = dbs_tuners_ins.sampling_rate *
		dbs_tuners_ins.sampling_down_factor;
	down_idle_ticks = (100 - dbs_tuners_ins.down_threshold) *
			usecs_to_jiffies(freq_down_sampling_rate);

	if (idle_ticks > down_idle_ticks) {
		/* if we are already at the lowest speed then break out early
		 * or if we 'cannot' reduce the speed as the user might want
		 * freq_step to be zero */
		if (requested_freq[cpu] == policy->min
				|| dbs_tuners_ins.freq_step == 0)
			return;

		freq_step = (dbs_tuners_ins.freq_step * policy->max) / 100;

		/* max freq cannot be less than 100. But who knows.... */
		if (unlikely(freq_step == 0))
			freq_step = 5;

		requested_freq[cpu] -= freq_step;
		if (requested_freq[cpu] < policy->min)
			requested_freq[cpu] = policy->min;

		__cpufreq_driver_target(policy,
			requested_freq[cpu],
			CPUFREQ_RELATION_H);
		return;
	}
}

static void do_dbs_timer(void *data)
{ 
	int i;
	down(&dbs_sem);
	for_each_online_cpu(i)
		dbs_check_cpu(i);
	schedule_delayed_work(&dbs_work, 
			usecs_to_jiffies(dbs_tuners_ins.sampling_rate));
	up(&dbs_sem);
} 

static inline void dbs_timer_init(void)
{
	INIT_WORK(&dbs_work, do_dbs_timer, NULL);
	schedule_delayed_work(&dbs_work,
			usecs_to_jiffies(dbs_tuners_ins.sampling_rate));
	return;
}

static inline void dbs_timer_exit(void)
{
	cancel_delayed_work(&dbs_work);
	return;
}

static int cpufreq_governor_dbs(struct cpufreq_policy *policy,
				   unsigned int event)
{
	unsigned int cpu = policy->cpu;
	struct cpu_dbs_info_s *this_dbs_info;
	unsigned int j;

	this_dbs_info = &per_cpu(cpu_dbs_info, cpu);

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

		if (policy->cpuinfo.transition_latency >
				(TRANSITION_LATENCY_LIMIT * 1000))
			return -EINVAL;
		if (this_dbs_info->enable) /* Already enabled */
			break;
		 
		down(&dbs_sem);
		for_each_cpu_mask(j, policy->cpus) {
			struct cpu_dbs_info_s *j_dbs_info;
			j_dbs_info = &per_cpu(cpu_dbs_info, j);
			j_dbs_info->cur_policy = policy;
		
			j_dbs_info->prev_cpu_idle_up = get_cpu_idle_time(j);
			j_dbs_info->prev_cpu_idle_down
				= j_dbs_info->prev_cpu_idle_up;
		}
		this_dbs_info->enable = 1;
		sysfs_create_group(&policy->kobj, &dbs_attr_group);
		dbs_enable++;
		/*
		 * Start the timerschedule work, when this governor
		 * is used for first time
		 */
		if (dbs_enable == 1) {
			unsigned int latency;
			/* policy latency is in nS. Convert it to uS first */

			latency = policy->cpuinfo.transition_latency;
			if (latency < 1000)
				latency = 1000;

			def_sampling_rate = (latency / 1000) *
					DEF_SAMPLING_RATE_LATENCY_MULTIPLIER;
			dbs_tuners_ins.sampling_rate = def_sampling_rate;
			dbs_tuners_ins.ignore_nice = 0;
			dbs_tuners_ins.freq_step = 5;

			dbs_timer_init();
		}
		
		up(&dbs_sem);
		break;

	case CPUFREQ_GOV_STOP:
		down(&dbs_sem);
		this_dbs_info->enable = 0;
		sysfs_remove_group(&policy->kobj, &dbs_attr_group);
		dbs_enable--;
		/*
		 * Stop the timerschedule work, when this governor
		 * is used for first time
		 */
		if (dbs_enable == 0) 
			dbs_timer_exit();
		
		up(&dbs_sem);

		break;

	case CPUFREQ_GOV_LIMITS:
		down(&dbs_sem);
		if (policy->max < this_dbs_info->cur_policy->cur)
			__cpufreq_driver_target(
					this_dbs_info->cur_policy,
				       	policy->max, CPUFREQ_RELATION_H);
		else if (policy->min > this_dbs_info->cur_policy->cur)
			__cpufreq_driver_target(
					this_dbs_info->cur_policy,
				       	policy->min, CPUFREQ_RELATION_L);
		up(&dbs_sem);
		break;
	}
	return 0;
}

static struct cpufreq_governor cpufreq_gov_dbs = {
	.name		= "conservative",
	.governor	= cpufreq_governor_dbs,
	.owner		= THIS_MODULE,
};

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

static void __exit cpufreq_gov_dbs_exit(void)
{
	/* Make sure that the scheduled work is indeed not running */
	flush_scheduled_work();

	cpufreq_unregister_governor(&cpufreq_gov_dbs);
}


MODULE_AUTHOR ("Alexander Clouter <alex-kernel@digriz.org.uk>");
MODULE_DESCRIPTION ("'cpufreq_conservative' - A dynamic cpufreq governor for "
		"Low Latency Frequency Transition capable processors "
		"optimised for use in a battery environment");
MODULE_LICENSE ("GPL");

module_init(cpufreq_gov_dbs_init);
module_exit(cpufreq_gov_dbs_exit);
Commit	Line	Data
b9170836 DJ	1	/*
	2	* drivers/cpufreq/cpufreq_conservative.c
	3	*
	4	* Copyright (C) 2001 Russell King
	5	* (C) 2003 Venkatesh Pallipadi <venkatesh.pallipadi@intel.com>.
	6	* Jun Nakajima <jun.nakajima@intel.com>
	7	* (C) 2004 Alexander Clouter <alex-kernel@digriz.org.uk>
	8	*
	9	* This program is free software; you can redistribute it and/or modify
	10	* it under the terms of the GNU General Public License version 2 as
	11	* published by the Free Software Foundation.
	12	*/
	13
	14	#include <linux/kernel.h>
	15	#include <linux/module.h>
	16	#include <linux/smp.h>
	17	#include <linux/init.h>
	18	#include <linux/interrupt.h>
	19	#include <linux/ctype.h>
	20	#include <linux/cpufreq.h>
	21	#include <linux/sysctl.h>
	22	#include <linux/types.h>
	23	#include <linux/fs.h>
	24	#include <linux/sysfs.h>
	25	#include <linux/sched.h>
	26	#include <linux/kmod.h>
	27	#include <linux/workqueue.h>
	28	#include <linux/jiffies.h>
	29	#include <linux/kernel_stat.h>
	30	#include <linux/percpu.h>
	31
	32	/*
	33	* dbs is used in this file as a shortform for demandbased switching
	34	* It helps to keep variable names smaller, simpler
	35	*/
	36
	37	#define DEF_FREQUENCY_UP_THRESHOLD (80)
	38	#define MIN_FREQUENCY_UP_THRESHOLD (0)
	39	#define MAX_FREQUENCY_UP_THRESHOLD (100)
	40
	41	#define DEF_FREQUENCY_DOWN_THRESHOLD (20)
	42	#define MIN_FREQUENCY_DOWN_THRESHOLD (0)
	43	#define MAX_FREQUENCY_DOWN_THRESHOLD (100)
	44
	45	/*
	46	* The polling frequency of this governor depends on the capability of
	47	* the processor. Default polling frequency is 1000 times the transition
	48	* latency of the processor. The governor will work on any processor with
	49	* transition latency <= 10mS, using appropriate sampling
	50	* rate.
	51	* For CPUs with transition latency > 10mS (mostly drivers with CPUFREQ_ETERNAL)
	52	* this governor will not work.
	53	* All times here are in uS.
	54	*/
	55	static unsigned int def_sampling_rate;
	56	#define MIN_SAMPLING_RATE (def_sampling_rate / 2)
	57	#define MAX_SAMPLING_RATE (500 * def_sampling_rate)
	58	#define DEF_SAMPLING_RATE_LATENCY_MULTIPLIER (100000)
	59	#define DEF_SAMPLING_DOWN_FACTOR (5)
	60	#define TRANSITION_LATENCY_LIMIT (10 * 1000)
	61
	62	static void do_dbs_timer(void *data);
	63
	64	struct cpu_dbs_info_s {
65	struct cpufreq_policy *cur_policy;
66	unsigned int prev_cpu_idle_up;
67	unsigned int prev_cpu_idle_down;
68	unsigned int enable;
69	};
70	static DEFINE_PER_CPU(struct cpu_dbs_info_s, cpu_dbs_info);
71
72	static unsigned int dbs_enable; /* number of CPUs using this policy */
73
74	static DECLARE_MUTEX (dbs_sem);
75	static DECLARE_WORK (dbs_work, do_dbs_timer, NULL);
76
77	struct dbs_tuners {
78	unsigned int sampling_rate;
79	unsigned int sampling_down_factor;
80	unsigned int up_threshold;
81	unsigned int down_threshold;
82	unsigned int ignore_nice;
83	unsigned int freq_step;
84	};
85
86	static struct dbs_tuners dbs_tuners_ins = {
87	.up_threshold = DEF_FREQUENCY_UP_THRESHOLD,
88	.down_threshold = DEF_FREQUENCY_DOWN_THRESHOLD,
89	.sampling_down_factor = DEF_SAMPLING_DOWN_FACTOR,
90	};
91
dac1c1a5 DJ	92	static inline unsigned int get_cpu_idle_time(unsigned int cpu)
	93	{
	94	return kstat_cpu(cpu).cpustat.idle +
	95	kstat_cpu(cpu).cpustat.iowait +
001893cd	96	( dbs_tuners_ins.ignore_nice ?
dac1c1a5 DJ	97	kstat_cpu(cpu).cpustat.nice :
	98	0);
	99	}
	100
b9170836 DJ	101	/************************ sysfs interface **********************/
	102	static ssize_t show_sampling_rate_max(struct cpufreq_policy policy, char buf)
	103	{
	104	return sprintf (buf, "%u\n", MAX_SAMPLING_RATE);
	105	}
	106
	107	static ssize_t show_sampling_rate_min(struct cpufreq_policy policy, char buf)
	108	{
	109	return sprintf (buf, "%u\n", MIN_SAMPLING_RATE);
	110	}
	111
	112	#define define_one_ro(_name) \
	113	static struct freq_attr _name = \
	114	__ATTR(_name, 0444, show_##_name, NULL)
	115
	116	define_one_ro(sampling_rate_max);
	117	define_one_ro(sampling_rate_min);
	118
	119	/* cpufreq_conservative Governor Tunables */
	120	#define show_one(file_name, object) \
	121	static ssize_t show_##file_name \
	122	(struct cpufreq_policy unused, char buf) \
	123	{ \
	124	return sprintf(buf, "%u\n", dbs_tuners_ins.object); \
	125	}
	126	show_one(sampling_rate, sampling_rate);
	127	show_one(sampling_down_factor, sampling_down_factor);
	128	show_one(up_threshold, up_threshold);
	129	show_one(down_threshold, down_threshold);
001893cd	130	show_one(ignore_nice_load, ignore_nice);
b9170836 DJ	131	show_one(freq_step, freq_step);
	132
	133	static ssize_t store_sampling_down_factor(struct cpufreq_policy *unused,
	134	const char *buf, size_t count)
	135	{
	136	unsigned int input;
	137	int ret;
	138	ret = sscanf (buf, "%u", &input);
	139	if (ret != 1 )
	140	return -EINVAL;
	141
	142	down(&dbs_sem);
	143	dbs_tuners_ins.sampling_down_factor = input;
	144	up(&dbs_sem);
	145
	146	return count;
	147	}
	148
	149	static ssize_t store_sampling_rate(struct cpufreq_policy *unused,
	150	const char *buf, size_t count)
	151	{
	152	unsigned int input;
	153	int ret;
	154	ret = sscanf (buf, "%u", &input);
	155
	156	down(&dbs_sem);
	157	if (ret != 1 \|\| input > MAX_SAMPLING_RATE \|\| input < MIN_SAMPLING_RATE) {
	158	up(&dbs_sem);
	159	return -EINVAL;
	160	}
	161
	162	dbs_tuners_ins.sampling_rate = input;
	163	up(&dbs_sem);
	164
	165	return count;
	166	}
	167
	168	static ssize_t store_up_threshold(struct cpufreq_policy *unused,
	169	const char *buf, size_t count)
	170	{
	171	unsigned int input;
	172	int ret;
	173	ret = sscanf (buf, "%u", &input);
	174
	175	down(&dbs_sem);
	176	if (ret != 1 \|\| input > MAX_FREQUENCY_UP_THRESHOLD \|\|
	177	input < MIN_FREQUENCY_UP_THRESHOLD \|\|
	178	input <= dbs_tuners_ins.down_threshold) {
	179	up(&dbs_sem);
	180	return -EINVAL;
	181	}
	182
	183	dbs_tuners_ins.up_threshold = input;
	184	up(&dbs_sem);
	185
	186	return count;
	187	}
	188
	189	static ssize_t store_down_threshold(struct cpufreq_policy *unused,
	190	const char *buf, size_t count)
	191	{
	192	unsigned int input;
	193	int ret;
	194	ret = sscanf (buf, "%u", &input);
195
196	down(&dbs_sem);
197	if (ret != 1 \|\| input > MAX_FREQUENCY_DOWN_THRESHOLD \|\|
198	input < MIN_FREQUENCY_DOWN_THRESHOLD \|\|
199	input >= dbs_tuners_ins.up_threshold) {
200	up(&dbs_sem);
201	return -EINVAL;
202	}
203
204	dbs_tuners_ins.down_threshold = input;
205	up(&dbs_sem);
206
207	return count;
208	}
209
001893cd	210	static ssize_t store_ignore_nice_load(struct cpufreq_policy *policy,
b9170836 DJ	211	const char *buf, size_t count)
	212	{
	213	unsigned int input;
	214	int ret;
	215
	216	unsigned int j;
	217
	218	ret = sscanf (buf, "%u", &input);
	219	if ( ret != 1 )
	220	return -EINVAL;
	221
	222	if ( input > 1 )
	223	input = 1;
	224
	225	down(&dbs_sem);
	226	if ( input == dbs_tuners_ins.ignore_nice ) { /* nothing to do */
	227	up(&dbs_sem);
	228	return count;
	229	}
	230	dbs_tuners_ins.ignore_nice = input;
	231
	232	/* we need to re-evaluate prev_cpu_idle_up and prev_cpu_idle_down */
dac1c1a5	233	for_each_online_cpu(j) {
b9170836 DJ	234	struct cpu_dbs_info_s *j_dbs_info;
b9170836 DJ	235	j_dbs_info = &per_cpu(cpu_dbs_info, j);
dac1c1a5	236	j_dbs_info->prev_cpu_idle_up = get_cpu_idle_time(j);
b9170836 DJ	237	j_dbs_info->prev_cpu_idle_down = j_dbs_info->prev_cpu_idle_up;
	238	}
	239	up(&dbs_sem);
	240
	241	return count;
	242	}
	243
	244	static ssize_t store_freq_step(struct cpufreq_policy *policy,
	245	const char *buf, size_t count)
	246	{
	247	unsigned int input;
	248	int ret;
	249
	250	ret = sscanf (buf, "%u", &input);
	251
	252	if ( ret != 1 )
	253	return -EINVAL;
	254
	255	if ( input > 100 )
	256	input = 100;
	257
	258	/* no need to test here if freq_step is zero as the user might actually
	259	* want this, they would be crazy though :) */
	260	down(&dbs_sem);
	261	dbs_tuners_ins.freq_step = input;
	262	up(&dbs_sem);
	263
	264	return count;
	265	}
	266
	267	#define define_one_rw(_name) \
	268	static struct freq_attr _name = \
	269	__ATTR(_name, 0644, show_##_name, store_##_name)
	270
	271	define_one_rw(sampling_rate);
	272	define_one_rw(sampling_down_factor);
	273	define_one_rw(up_threshold);
	274	define_one_rw(down_threshold);
001893cd	275	define_one_rw(ignore_nice_load);
b9170836 DJ	276	define_one_rw(freq_step);
	277
	278	static struct attribute * dbs_attributes[] = {
	279	&sampling_rate_max.attr,
	280	&sampling_rate_min.attr,
	281	&sampling_rate.attr,
	282	&sampling_down_factor.attr,
	283	&up_threshold.attr,
	284	&down_threshold.attr,
001893cd	285	&ignore_nice_load.attr,
b9170836 DJ	286	&freq_step.attr,
	287	NULL
	288	};
	289
	290	static struct attribute_group dbs_attr_group = {
	291	.attrs = dbs_attributes,
	292	.name = "conservative",
	293	};
	294
	295	/************************ sysfs end **********************/
	296
	297	static void dbs_check_cpu(int cpu)
	298	{
	299	unsigned int idle_ticks, up_idle_ticks, down_idle_ticks;
b9170836 DJ	300	unsigned int freq_step;
	301	unsigned int freq_down_sampling_rate;
	302	static int down_skip[NR_CPUS];
	303	static int requested_freq[NR_CPUS];
	304	static unsigned short init_flag = 0;
	305	struct cpu_dbs_info_s *this_dbs_info;
	306	struct cpu_dbs_info_s *dbs_info;
	307
	308	struct cpufreq_policy *policy;
	309	unsigned int j;
	310
	311	this_dbs_info = &per_cpu(cpu_dbs_info, cpu);
	312	if (!this_dbs_info->enable)
	313	return;
	314
	315	policy = this_dbs_info->cur_policy;
	316
	317	if ( init_flag == 0 ) {
92732144 DJ	318	for_each_online_cpu(j) {
	319	dbs_info = &per_cpu(cpu_dbs_info, j);
	320	requested_freq[j] = dbs_info->cur_policy->cur;
b9170836 DJ	321	}
	322	init_flag = 1;
	323	}
	324
	325	/*
	326	* The default safe range is 20% to 80%
	327	* Every sampling_rate, we check
	328	* - If current idle time is less than 20%, then we try to
	329	* increase frequency
	330	* Every sampling_rate*sampling_down_factor, we check
	331	* - If current idle time is more than 80%, then we try to
	332	* decrease frequency
	333	*
	334	* Any frequency increase takes it to the maximum frequency.
	335	* Frequency reduction happens at minimum steps of
	336	* 5% (default) of max_frequency
	337	*/
	338
	339	/* Check for frequency increase */
b9170836	340
9c7d269b	341	idle_ticks = UINT_MAX;
b9170836	342	for_each_cpu_mask(j, policy->cpus) {
9c7d269b	343	unsigned int tmp_idle_ticks, total_idle_ticks;
b9170836 DJ	344	struct cpu_dbs_info_s *j_dbs_info;
b9170836 DJ	345
b9170836 DJ	346	j_dbs_info = &per_cpu(cpu_dbs_info, j);
b9170836 DJ	347	/* Check for frequency increase */
dac1c1a5	348	total_idle_ticks = get_cpu_idle_time(j);
b9170836 DJ	349	tmp_idle_ticks = total_idle_ticks -
	350	j_dbs_info->prev_cpu_idle_up;
	351	j_dbs_info->prev_cpu_idle_up = total_idle_ticks;
	352
	353	if (tmp_idle_ticks < idle_ticks)
	354	idle_ticks = tmp_idle_ticks;
	355	}
	356
	357	/* Scale idle ticks by 100 and compare with up and down ticks */
	358	idle_ticks *= 100;
	359	up_idle_ticks = (100 - dbs_tuners_ins.up_threshold) *
	360	usecs_to_jiffies(dbs_tuners_ins.sampling_rate);
	361
	362	if (idle_ticks < up_idle_ticks) {
dac1c1a5	363	down_skip[cpu] = 0;
790d76fa DJ	364	for_each_cpu_mask(j, policy->cpus) {
	365	struct cpu_dbs_info_s *j_dbs_info;
	366
	367	j_dbs_info = &per_cpu(cpu_dbs_info, j);
	368	j_dbs_info->prev_cpu_idle_down =
	369	j_dbs_info->prev_cpu_idle_up;
	370	}
b9170836 DJ	371	/* if we are already at full speed then break out early */
	372	if (requested_freq[cpu] == policy->max)
	373	return;
	374
	375	freq_step = (dbs_tuners_ins.freq_step * policy->max) / 100;
	376
	377	/* max freq cannot be less than 100. But who knows.... */
	378	if (unlikely(freq_step == 0))
	379	freq_step = 5;
	380
	381	requested_freq[cpu] += freq_step;
	382	if (requested_freq[cpu] > policy->max)
	383	requested_freq[cpu] = policy->max;
	384
	385	__cpufreq_driver_target(policy, requested_freq[cpu],
	386	CPUFREQ_RELATION_H);
b9170836 DJ	387	return;
	388	}
	389
	390	/* Check for frequency decrease */
	391	down_skip[cpu]++;
	392	if (down_skip[cpu] < dbs_tuners_ins.sampling_down_factor)
	393	return;
	394
9c7d269b	395	idle_ticks = UINT_MAX;
b9170836	396	for_each_cpu_mask(j, policy->cpus) {
9c7d269b	397	unsigned int tmp_idle_ticks, total_idle_ticks;
b9170836 DJ	398	struct cpu_dbs_info_s *j_dbs_info;
b9170836 DJ	399
b9170836	400	j_dbs_info = &per_cpu(cpu_dbs_info, j);
dac1c1a5	401	total_idle_ticks = j_dbs_info->prev_cpu_idle_up;
b9170836 DJ	402	tmp_idle_ticks = total_idle_ticks -
	403	j_dbs_info->prev_cpu_idle_down;
	404	j_dbs_info->prev_cpu_idle_down = total_idle_ticks;
	405
	406	if (tmp_idle_ticks < idle_ticks)
	407	idle_ticks = tmp_idle_ticks;
	408	}
	409
	410	/* Scale idle ticks by 100 and compare with up and down ticks */
	411	idle_ticks *= 100;
	412	down_skip[cpu] = 0;
	413
	414	freq_down_sampling_rate = dbs_tuners_ins.sampling_rate *
	415	dbs_tuners_ins.sampling_down_factor;
	416	down_idle_ticks = (100 - dbs_tuners_ins.down_threshold) *
	417	usecs_to_jiffies(freq_down_sampling_rate);
	418
9c7d269b	419	if (idle_ticks > down_idle_ticks) {
b9170836 DJ	420	/* if we are already at the lowest speed then break out early
	421	* or if we 'cannot' reduce the speed as the user might want
	422	* freq_step to be zero */
	423	if (requested_freq[cpu] == policy->min
	424	\|\| dbs_tuners_ins.freq_step == 0)
	425	return;
	426
	427	freq_step = (dbs_tuners_ins.freq_step * policy->max) / 100;
	428
	429	/* max freq cannot be less than 100. But who knows.... */
	430	if (unlikely(freq_step == 0))
	431	freq_step = 5;
	432
	433	requested_freq[cpu] -= freq_step;
	434	if (requested_freq[cpu] < policy->min)
	435	requested_freq[cpu] = policy->min;
	436
	437	__cpufreq_driver_target(policy,
	438	requested_freq[cpu],
	439	CPUFREQ_RELATION_H);
	440	return;
	441	}
	442	}
	443
	444	static void do_dbs_timer(void *data)
	445	{
	446	int i;
	447	down(&dbs_sem);
	448	for_each_online_cpu(i)
	449	dbs_check_cpu(i);
	450	schedule_delayed_work(&dbs_work,
	451	usecs_to_jiffies(dbs_tuners_ins.sampling_rate));
	452	up(&dbs_sem);
	453	}
	454
	455	static inline void dbs_timer_init(void)
	456	{
	457	INIT_WORK(&dbs_work, do_dbs_timer, NULL);
	458	schedule_delayed_work(&dbs_work,
	459	usecs_to_jiffies(dbs_tuners_ins.sampling_rate));
	460	return;
	461	}
	462
	463	static inline void dbs_timer_exit(void)
	464	{
	465	cancel_delayed_work(&dbs_work);
	466	return;
	467	}
	468
	469	static int cpufreq_governor_dbs(struct cpufreq_policy *policy,
	470	unsigned int event)
	471	{
	472	unsigned int cpu = policy->cpu;
	473	struct cpu_dbs_info_s *this_dbs_info;
	474	unsigned int j;
	475
	476	this_dbs_info = &per_cpu(cpu_dbs_info, cpu);
	477
	478	switch (event) {
	479	case CPUFREQ_GOV_START:
	480	if ((!cpu_online(cpu)) \|\|
	481	(!policy->cur))
	482	return -EINVAL;
	483
484	if (policy->cpuinfo.transition_latency >
485	(TRANSITION_LATENCY_LIMIT * 1000))
486	return -EINVAL;
487	if (this_dbs_info->enable) /* Already enabled */
488	break;
489
490	down(&dbs_sem);
491	for_each_cpu_mask(j, policy->cpus) {
492	struct cpu_dbs_info_s *j_dbs_info;
493	j_dbs_info = &per_cpu(cpu_dbs_info, j);
494	j_dbs_info->cur_policy = policy;
495
dac1c1a5	496	j_dbs_info->prev_cpu_idle_up = get_cpu_idle_time(j);
b9170836 DJ	497	j_dbs_info->prev_cpu_idle_down
	498	= j_dbs_info->prev_cpu_idle_up;
	499	}
	500	this_dbs_info->enable = 1;
	501	sysfs_create_group(&policy->kobj, &dbs_attr_group);
	502	dbs_enable++;
	503	/*
	504	* Start the timerschedule work, when this governor
	505	* is used for first time
	506	*/
	507	if (dbs_enable == 1) {
	508	unsigned int latency;
	509	/* policy latency is in nS. Convert it to uS first */
	510
	511	latency = policy->cpuinfo.transition_latency;
	512	if (latency < 1000)
	513	latency = 1000;
	514
	515	def_sampling_rate = (latency / 1000) *
	516	DEF_SAMPLING_RATE_LATENCY_MULTIPLIER;
	517	dbs_tuners_ins.sampling_rate = def_sampling_rate;
	518	dbs_tuners_ins.ignore_nice = 0;
	519	dbs_tuners_ins.freq_step = 5;
	520
	521	dbs_timer_init();
	522	}
	523
	524	up(&dbs_sem);
	525	break;
	526
	527	case CPUFREQ_GOV_STOP:
	528	down(&dbs_sem);
	529	this_dbs_info->enable = 0;
	530	sysfs_remove_group(&policy->kobj, &dbs_attr_group);
	531	dbs_enable--;
	532	/*
	533	* Stop the timerschedule work, when this governor
	534	* is used for first time
	535	*/
	536	if (dbs_enable == 0)
	537	dbs_timer_exit();
	538
	539	up(&dbs_sem);
	540
	541	break;
	542
	543	case CPUFREQ_GOV_LIMITS:
	544	down(&dbs_sem);
	545	if (policy->max < this_dbs_info->cur_policy->cur)
	546	__cpufreq_driver_target(
	547	this_dbs_info->cur_policy,
	548	policy->max, CPUFREQ_RELATION_H);
	549	else if (policy->min > this_dbs_info->cur_policy->cur)
	550	__cpufreq_driver_target(
	551	this_dbs_info->cur_policy,
	552	policy->min, CPUFREQ_RELATION_L);
	553	up(&dbs_sem);
	554	break;
	555	}
	556	return 0;
	557	}
	558
	559	static struct cpufreq_governor cpufreq_gov_dbs = {
	560	.name = "conservative",
561	.governor = cpufreq_governor_dbs,
562	.owner = THIS_MODULE,
563	};
564
565	static int __init cpufreq_gov_dbs_init(void)
566	{
567	return cpufreq_register_governor(&cpufreq_gov_dbs);
568	}
569
570	static void __exit cpufreq_gov_dbs_exit(void)
571	{
572	/* Make sure that the scheduled work is indeed not running */
573	flush_scheduled_work();
574
575	cpufreq_unregister_governor(&cpufreq_gov_dbs);
576	}
577
578
579	MODULE_AUTHOR ("Alexander Clouter <alex-kernel@digriz.org.uk>");
580	MODULE_DESCRIPTION ("'cpufreq_conservative' - A dynamic cpufreq governor for "
581	"Low Latency Frequency Transition capable processors "
582	"optimised for use in a battery environment");
583	MODULE_LICENSE ("GPL");
584
585	module_init(cpufreq_gov_dbs_init);
586	module_exit(cpufreq_gov_dbs_exit);