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

/*
 *  drivers/cpufreq/cpufreq_ondemand.c
 *
 *  Copyright (C)  2001 Russell King
 *            (C)  2003 Venkatesh Pallipadi <venkatesh.pallipadi@intel.com>.
 *                      Jun Nakajima <jun.nakajima@intel.com>
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License version 2 as
 * published by the Free Software Foundation.
 */

#include <linux/kernel.h>
#include <linux/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		(11)
#define MAX_FREQUENCY_UP_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	(1000)
#define DEF_SAMPLING_DOWN_FACTOR		(1)
#define MAX_SAMPLING_DOWN_FACTOR		(10)
#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		ignore_nice;
};

static struct dbs_tuners dbs_tuners_ins = {
	.up_threshold 		= DEF_FREQUENCY_UP_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_ondemand 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(ignore_nice, ignore_nice);

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;

	if (input > MAX_SAMPLING_DOWN_FACTOR || input < 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) {
		up(&dbs_sem);
		return -EINVAL;
	}

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

	return count;
}

static ssize_t store_ignore_nice(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;
}

#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(ignore_nice);

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

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

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

static void dbs_check_cpu(int cpu)
{
	unsigned int idle_ticks, up_idle_ticks, total_ticks;
	unsigned int freq_next;
	unsigned int freq_down_sampling_rate;
	static int down_skip[NR_CPUS];
	struct cpu_dbs_info_s *this_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;
	/* 
	 * Every sampling_rate, we check, if current idle time is less
	 * than 20% (default), then we try to increase frequency
	 * Every sampling_rate*sampling_down_factor, we look for a the lowest
	 * frequency which can sustain the load while keeping idle time over
	 * 30%. If such a frequency exist, we try to decrease to this frequency.
	 *
	 * Any frequency increase takes it to the maximum frequency. 
	 * Frequency reduction happens at minimum steps of 
	 * 5% (default) of current 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);
		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 (policy->cur == policy->max)
			return;
		
		__cpufreq_driver_target(policy, policy->max, 
			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);
		/* Check for frequency decrease */
		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;
	}

	down_skip[cpu] = 0;
	/* if we cannot reduce the frequency anymore, break out early */
	if (policy->cur == policy->min)
		return;

	/* Compute how many ticks there are between two measurements */
	freq_down_sampling_rate = dbs_tuners_ins.sampling_rate *
		dbs_tuners_ins.sampling_down_factor;
	total_ticks = usecs_to_jiffies(freq_down_sampling_rate);

	/*
	 * The optimal frequency is the frequency that is the lowest that
	 * can support the current CPU usage without triggering the up
	 * policy. To be safe, we focus 10 points under the threshold.
	 */
	freq_next = ((total_ticks - idle_ticks) * 100) / total_ticks;
	freq_next = (freq_next * policy->cur) / 
			(dbs_tuners_ins.up_threshold - 10);

	if (freq_next <= ((policy->cur * 95) / 100))
		__cpufreq_driver_target(policy, freq_next, CPUFREQ_RELATION_L);
}

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_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		= "ondemand",
	.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 ("Venkatesh Pallipadi <venkatesh.pallipadi@intel.com>");
MODULE_DESCRIPTION ("'cpufreq_ondemand' - A dynamic cpufreq governor for "
		"Low Latency Frequency Transition capable processors");
MODULE_LICENSE ("GPL");

module_init(cpufreq_gov_dbs_init);
module_exit(cpufreq_gov_dbs_exit);
Commit	Line	Data
1da177e4 LT	1	/*
	2	* drivers/cpufreq/cpufreq_ondemand.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	*
	8	* This program is free software; you can redistribute it and/or modify
	9	* it under the terms of the GNU General Public License version 2 as
	10	* published by the Free Software Foundation.
	11	*/
	12
	13	#include <linux/kernel.h>
	14	#include <linux/module.h>
	15	#include <linux/smp.h>
	16	#include <linux/init.h>
	17	#include <linux/interrupt.h>
	18	#include <linux/ctype.h>
	19	#include <linux/cpufreq.h>
	20	#include <linux/sysctl.h>
	21	#include <linux/types.h>
	22	#include <linux/fs.h>
	23	#include <linux/sysfs.h>
	24	#include <linux/sched.h>
	25	#include <linux/kmod.h>
	26	#include <linux/workqueue.h>
	27	#include <linux/jiffies.h>
	28	#include <linux/kernel_stat.h>
	29	#include <linux/percpu.h>
	30
	31	/*
	32	* dbs is used in this file as a shortform for demandbased switching
	33	* It helps to keep variable names smaller, simpler
	34	*/
	35
	36	#define DEF_FREQUENCY_UP_THRESHOLD (80)
c29f1403	37	#define MIN_FREQUENCY_UP_THRESHOLD (11)
1da177e4 LT	38	#define MAX_FREQUENCY_UP_THRESHOLD (100)
1da177e4 LT	39
1da177e4 LT	40	/*
	41	* The polling frequency of this governor depends on the capability of
	42	* the processor. Default polling frequency is 1000 times the transition
	43	* latency of the processor. The governor will work on any processor with
	44	* transition latency <= 10mS, using appropriate sampling
	45	* rate.
	46	* For CPUs with transition latency > 10mS (mostly drivers with CPUFREQ_ETERNAL)
	47	* this governor will not work.
	48	* All times here are in uS.
	49	*/
	50	static unsigned int def_sampling_rate;
	51	#define MIN_SAMPLING_RATE (def_sampling_rate / 2)
	52	#define MAX_SAMPLING_RATE (500 * def_sampling_rate)
	53	#define DEF_SAMPLING_RATE_LATENCY_MULTIPLIER (1000)
e131832c DJ	54	#define DEF_SAMPLING_DOWN_FACTOR (1)
e131832c DJ	55	#define MAX_SAMPLING_DOWN_FACTOR (10)
1da177e4	56	#define TRANSITION_LATENCY_LIMIT (10 * 1000)
1da177e4 LT	57
	58	static void do_dbs_timer(void *data);
	59
	60	struct cpu_dbs_info_s {
	61	struct cpufreq_policy *cur_policy;
	62	unsigned int prev_cpu_idle_up;
	63	unsigned int prev_cpu_idle_down;
	64	unsigned int enable;
	65	};
	66	static DEFINE_PER_CPU(struct cpu_dbs_info_s, cpu_dbs_info);
	67
	68	static unsigned int dbs_enable; /* number of CPUs using this policy */
	69
	70	static DECLARE_MUTEX (dbs_sem);
	71	static DECLARE_WORK (dbs_work, do_dbs_timer, NULL);
	72
	73	struct dbs_tuners {
	74	unsigned int sampling_rate;
	75	unsigned int sampling_down_factor;
	76	unsigned int up_threshold;
3d5ee9e5	77	unsigned int ignore_nice;
1da177e4 LT	78	};
	79
	80	static struct dbs_tuners dbs_tuners_ins = {
	81	.up_threshold = DEF_FREQUENCY_UP_THRESHOLD,
1da177e4 LT	82	.sampling_down_factor = DEF_SAMPLING_DOWN_FACTOR,
	83	};
	84
dac1c1a5 DJ	85	static inline unsigned int get_cpu_idle_time(unsigned int cpu)
	86	{
	87	return kstat_cpu(cpu).cpustat.idle +
	88	kstat_cpu(cpu).cpustat.iowait +
	89	( !dbs_tuners_ins.ignore_nice ?
	90	kstat_cpu(cpu).cpustat.nice :
	91	0);
	92	}
	93
1da177e4 LT	94	/************************ sysfs interface **********************/
	95	static ssize_t show_sampling_rate_max(struct cpufreq_policy policy, char buf)
	96	{
	97	return sprintf (buf, "%u\n", MAX_SAMPLING_RATE);
	98	}
	99
	100	static ssize_t show_sampling_rate_min(struct cpufreq_policy policy, char buf)
	101	{
	102	return sprintf (buf, "%u\n", MIN_SAMPLING_RATE);
	103	}
	104
	105	#define define_one_ro(_name) \
	106	static struct freq_attr _name = \
	107	__ATTR(_name, 0444, show_##_name, NULL)
	108
	109	define_one_ro(sampling_rate_max);
	110	define_one_ro(sampling_rate_min);
	111
	112	/* cpufreq_ondemand Governor Tunables */
	113	#define show_one(file_name, object) \
	114	static ssize_t show_##file_name \
	115	(struct cpufreq_policy unused, char buf) \
	116	{ \
	117	return sprintf(buf, "%u\n", dbs_tuners_ins.object); \
	118	}
	119	show_one(sampling_rate, sampling_rate);
	120	show_one(sampling_down_factor, sampling_down_factor);
	121	show_one(up_threshold, up_threshold);
3d5ee9e5	122	show_one(ignore_nice, ignore_nice);
1da177e4 LT	123
	124	static ssize_t store_sampling_down_factor(struct cpufreq_policy *unused,
	125	const char *buf, size_t count)
	126	{
	127	unsigned int input;
	128	int ret;
	129	ret = sscanf (buf, "%u", &input);
	130	if (ret != 1 )
	131	return -EINVAL;
	132
e131832c DJ	133	if (input > MAX_SAMPLING_DOWN_FACTOR \|\| input < 1)
	134	return -EINVAL;
	135
1da177e4 LT	136	down(&dbs_sem);
	137	dbs_tuners_ins.sampling_down_factor = input;
	138	up(&dbs_sem);
	139
	140	return count;
	141	}
	142
	143	static ssize_t store_sampling_rate(struct cpufreq_policy *unused,
	144	const char *buf, size_t count)
	145	{
	146	unsigned int input;
	147	int ret;
	148	ret = sscanf (buf, "%u", &input);
	149
	150	down(&dbs_sem);
	151	if (ret != 1 \|\| input > MAX_SAMPLING_RATE \|\| input < MIN_SAMPLING_RATE) {
	152	up(&dbs_sem);
	153	return -EINVAL;
	154	}
	155
	156	dbs_tuners_ins.sampling_rate = input;
	157	up(&dbs_sem);
	158
	159	return count;
	160	}
	161
	162	static ssize_t store_up_threshold(struct cpufreq_policy *unused,
	163	const char *buf, size_t count)
	164	{
	165	unsigned int input;
	166	int ret;
	167	ret = sscanf (buf, "%u", &input);
	168
	169	down(&dbs_sem);
	170	if (ret != 1 \|\| input > MAX_FREQUENCY_UP_THRESHOLD \|\|
c29f1403	171	input < MIN_FREQUENCY_UP_THRESHOLD) {
1da177e4 LT	172	up(&dbs_sem);
	173	return -EINVAL;
	174	}
	175
	176	dbs_tuners_ins.up_threshold = input;
	177	up(&dbs_sem);
	178
	179	return count;
	180	}
	181
3d5ee9e5 DJ	182	static ssize_t store_ignore_nice(struct cpufreq_policy *policy,
	183	const char *buf, size_t count)
	184	{
	185	unsigned int input;
	186	int ret;
	187
	188	unsigned int j;
	189
	190	ret = sscanf (buf, "%u", &input);
	191	if ( ret != 1 )
	192	return -EINVAL;
	193
	194	if ( input > 1 )
	195	input = 1;
	196
	197	down(&dbs_sem);
	198	if ( input == dbs_tuners_ins.ignore_nice ) { /* nothing to do */
	199	up(&dbs_sem);
	200	return count;
	201	}
	202	dbs_tuners_ins.ignore_nice = input;
	203
	204	/* we need to re-evaluate prev_cpu_idle_up and prev_cpu_idle_down */
dac1c1a5	205	for_each_online_cpu(j) {
3d5ee9e5 DJ	206	struct cpu_dbs_info_s *j_dbs_info;
3d5ee9e5 DJ	207	j_dbs_info = &per_cpu(cpu_dbs_info, j);
dac1c1a5	208	j_dbs_info->prev_cpu_idle_up = get_cpu_idle_time(j);
3d5ee9e5 DJ	209	j_dbs_info->prev_cpu_idle_down = j_dbs_info->prev_cpu_idle_up;
	210	}
	211	up(&dbs_sem);
	212
	213	return count;
	214	}
	215
1da177e4 LT	216	#define define_one_rw(_name) \
	217	static struct freq_attr _name = \
	218	__ATTR(_name, 0644, show_##_name, store_##_name)
	219
	220	define_one_rw(sampling_rate);
	221	define_one_rw(sampling_down_factor);
	222	define_one_rw(up_threshold);
3d5ee9e5	223	define_one_rw(ignore_nice);
1da177e4 LT	224
	225	static struct attribute * dbs_attributes[] = {
	226	&sampling_rate_max.attr,
	227	&sampling_rate_min.attr,
	228	&sampling_rate.attr,
	229	&sampling_down_factor.attr,
	230	&up_threshold.attr,
3d5ee9e5	231	&ignore_nice.attr,
1da177e4 LT	232	NULL
	233	};
	234
	235	static struct attribute_group dbs_attr_group = {
	236	.attrs = dbs_attributes,
	237	.name = "ondemand",
	238	};
	239
	240	/************************ sysfs end **********************/
	241
	242	static void dbs_check_cpu(int cpu)
	243	{
c29f1403 DJ	244	unsigned int idle_ticks, up_idle_ticks, total_ticks;
c29f1403 DJ	245	unsigned int freq_next;
1da177e4 LT	246	unsigned int freq_down_sampling_rate;
	247	static int down_skip[NR_CPUS];
	248	struct cpu_dbs_info_s *this_dbs_info;
	249
	250	struct cpufreq_policy *policy;
	251	unsigned int j;
	252
	253	this_dbs_info = &per_cpu(cpu_dbs_info, cpu);
	254	if (!this_dbs_info->enable)
	255	return;
	256
	257	policy = this_dbs_info->cur_policy;
	258	/*
c29f1403 DJ	259	* Every sampling_rate, we check, if current idle time is less
	260	* than 20% (default), then we try to increase frequency
	261	* Every sampling_rate*sampling_down_factor, we look for a the lowest
	262	* frequency which can sustain the load while keeping idle time over
	263	* 30%. If such a frequency exist, we try to decrease to this frequency.
1da177e4 LT	264	*
	265	* Any frequency increase takes it to the maximum frequency.
	266	* Frequency reduction happens at minimum steps of
c29f1403	267	* 5% (default) of current frequency
1da177e4 LT	268	*/
	269
	270	/* Check for frequency increase */
9c7d269b	271	idle_ticks = UINT_MAX;
1da177e4	272	for_each_cpu_mask(j, policy->cpus) {
9c7d269b	273	unsigned int tmp_idle_ticks, total_idle_ticks;
1da177e4 LT	274	struct cpu_dbs_info_s *j_dbs_info;
1da177e4 LT	275
1da177e4	276	j_dbs_info = &per_cpu(cpu_dbs_info, j);
dac1c1a5	277	total_idle_ticks = get_cpu_idle_time(j);
1da177e4 LT	278	tmp_idle_ticks = total_idle_ticks -
	279	j_dbs_info->prev_cpu_idle_up;
	280	j_dbs_info->prev_cpu_idle_up = total_idle_ticks;
	281
	282	if (tmp_idle_ticks < idle_ticks)
	283	idle_ticks = tmp_idle_ticks;
	284	}
	285
	286	/* Scale idle ticks by 100 and compare with up and down ticks */
	287	idle_ticks *= 100;
	288	up_idle_ticks = (100 - dbs_tuners_ins.up_threshold) *
6fe71165	289	usecs_to_jiffies(dbs_tuners_ins.sampling_rate);
1da177e4 LT	290
1da177e4 LT	291	if (idle_ticks < up_idle_ticks) {
dac1c1a5	292	down_skip[cpu] = 0;
790d76fa DJ	293	for_each_cpu_mask(j, policy->cpus) {
	294	struct cpu_dbs_info_s *j_dbs_info;
	295
	296	j_dbs_info = &per_cpu(cpu_dbs_info, j);
	297	j_dbs_info->prev_cpu_idle_down =
	298	j_dbs_info->prev_cpu_idle_up;
	299	}
c11420a6 DJ	300	/* if we are already at full speed then break out early */
	301	if (policy->cur == policy->max)
	302	return;
	303
1da177e4 LT	304	__cpufreq_driver_target(policy, policy->max,
1da177e4 LT	305	CPUFREQ_RELATION_H);
1da177e4 LT	306	return;
	307	}
	308
	309	/* Check for frequency decrease */
	310	down_skip[cpu]++;
	311	if (down_skip[cpu] < dbs_tuners_ins.sampling_down_factor)
	312	return;
	313
9c7d269b	314	idle_ticks = UINT_MAX;
1da177e4	315	for_each_cpu_mask(j, policy->cpus) {
9c7d269b	316	unsigned int tmp_idle_ticks, total_idle_ticks;
1da177e4 LT	317	struct cpu_dbs_info_s *j_dbs_info;
1da177e4 LT	318
1da177e4	319	j_dbs_info = &per_cpu(cpu_dbs_info, j);
dac1c1a5 DJ	320	/* Check for frequency decrease */
dac1c1a5 DJ	321	total_idle_ticks = j_dbs_info->prev_cpu_idle_up;
1da177e4 LT	322	tmp_idle_ticks = total_idle_ticks -
	323	j_dbs_info->prev_cpu_idle_down;
	324	j_dbs_info->prev_cpu_idle_down = total_idle_ticks;
	325
	326	if (tmp_idle_ticks < idle_ticks)
	327	idle_ticks = tmp_idle_ticks;
	328	}
	329
1da177e4	330	down_skip[cpu] = 0;
c29f1403 DJ	331	/* if we cannot reduce the frequency anymore, break out early */
	332	if (policy->cur == policy->min)
	333	return;
1da177e4	334
c29f1403	335	/* Compute how many ticks there are between two measurements */
1da177e4 LT	336	freq_down_sampling_rate = dbs_tuners_ins.sampling_rate *
1da177e4 LT	337	dbs_tuners_ins.sampling_down_factor;
c29f1403	338	total_ticks = usecs_to_jiffies(freq_down_sampling_rate);
1206aaac	339
c29f1403 DJ	340	/*
	341	* The optimal frequency is the frequency that is the lowest that
	342	* can support the current CPU usage without triggering the up
	343	* policy. To be safe, we focus 10 points under the threshold.
	344	*/
	345	freq_next = ((total_ticks - idle_ticks) * 100) / total_ticks;
	346	freq_next = (freq_next * policy->cur) /
	347	(dbs_tuners_ins.up_threshold - 10);
1da177e4	348
c29f1403 DJ	349	if (freq_next <= ((policy->cur * 95) / 100))
c29f1403 DJ	350	__cpufreq_driver_target(policy, freq_next, CPUFREQ_RELATION_L);
1da177e4 LT	351	}
	352
	353	static void do_dbs_timer(void *data)
	354	{
	355	int i;
	356	down(&dbs_sem);
6fe71165 DJ	357	for_each_online_cpu(i)
6fe71165 DJ	358	dbs_check_cpu(i);
1da177e4	359	schedule_delayed_work(&dbs_work,
6fe71165	360	usecs_to_jiffies(dbs_tuners_ins.sampling_rate));
1da177e4 LT	361	up(&dbs_sem);
	362	}
	363
	364	static inline void dbs_timer_init(void)
	365	{
	366	INIT_WORK(&dbs_work, do_dbs_timer, NULL);
	367	schedule_delayed_work(&dbs_work,
6fe71165	368	usecs_to_jiffies(dbs_tuners_ins.sampling_rate));
1da177e4 LT	369	return;
	370	}
	371
	372	static inline void dbs_timer_exit(void)
	373	{
	374	cancel_delayed_work(&dbs_work);
	375	return;
	376	}
	377
	378	static int cpufreq_governor_dbs(struct cpufreq_policy *policy,
	379	unsigned int event)
	380	{
	381	unsigned int cpu = policy->cpu;
	382	struct cpu_dbs_info_s *this_dbs_info;
	383	unsigned int j;
	384
	385	this_dbs_info = &per_cpu(cpu_dbs_info, cpu);
	386
	387	switch (event) {
	388	case CPUFREQ_GOV_START:
	389	if ((!cpu_online(cpu)) \|\|
	390	(!policy->cur))
	391	return -EINVAL;
	392
	393	if (policy->cpuinfo.transition_latency >
	394	(TRANSITION_LATENCY_LIMIT * 1000))
	395	return -EINVAL;
	396	if (this_dbs_info->enable) /* Already enabled */
	397	break;
	398
	399	down(&dbs_sem);
	400	for_each_cpu_mask(j, policy->cpus) {
	401	struct cpu_dbs_info_s *j_dbs_info;
	402	j_dbs_info = &per_cpu(cpu_dbs_info, j);
	403	j_dbs_info->cur_policy = policy;
	404
dac1c1a5	405	j_dbs_info->prev_cpu_idle_up = get_cpu_idle_time(j);
3d5ee9e5 DJ	406	j_dbs_info->prev_cpu_idle_down
3d5ee9e5 DJ	407	= j_dbs_info->prev_cpu_idle_up;
1da177e4 LT	408	}
	409	this_dbs_info->enable = 1;
	410	sysfs_create_group(&policy->kobj, &dbs_attr_group);
	411	dbs_enable++;
	412	/*
	413	* Start the timerschedule work, when this governor
	414	* is used for first time
	415	*/
	416	if (dbs_enable == 1) {
	417	unsigned int latency;
	418	/* policy latency is in nS. Convert it to uS first */
	419
	420	latency = policy->cpuinfo.transition_latency;
	421	if (latency < 1000)
	422	latency = 1000;
	423
	424	def_sampling_rate = (latency / 1000) *
	425	DEF_SAMPLING_RATE_LATENCY_MULTIPLIER;
	426	dbs_tuners_ins.sampling_rate = def_sampling_rate;
3d5ee9e5	427	dbs_tuners_ins.ignore_nice = 0;
1da177e4 LT	428
	429	dbs_timer_init();
	430	}
	431
	432	up(&dbs_sem);
	433	break;
	434
	435	case CPUFREQ_GOV_STOP:
	436	down(&dbs_sem);
	437	this_dbs_info->enable = 0;
	438	sysfs_remove_group(&policy->kobj, &dbs_attr_group);
	439	dbs_enable--;
	440	/*
	441	* Stop the timerschedule work, when this governor
	442	* is used for first time
	443	*/
	444	if (dbs_enable == 0)
	445	dbs_timer_exit();
	446
	447	up(&dbs_sem);
	448
	449	break;
	450
	451	case CPUFREQ_GOV_LIMITS:
	452	down(&dbs_sem);
	453	if (policy->max < this_dbs_info->cur_policy->cur)
	454	__cpufreq_driver_target(
	455	this_dbs_info->cur_policy,
	456	policy->max, CPUFREQ_RELATION_H);
	457	else if (policy->min > this_dbs_info->cur_policy->cur)
	458	__cpufreq_driver_target(
	459	this_dbs_info->cur_policy,
	460	policy->min, CPUFREQ_RELATION_L);
	461	up(&dbs_sem);
	462	break;
	463	}
	464	return 0;
	465	}
	466
7f335d4e	467	static struct cpufreq_governor cpufreq_gov_dbs = {
1da177e4 LT	468	.name = "ondemand",
	469	.governor = cpufreq_governor_dbs,
	470	.owner = THIS_MODULE,
	471	};
1da177e4 LT	472
	473	static int __init cpufreq_gov_dbs_init(void)
	474	{
	475	return cpufreq_register_governor(&cpufreq_gov_dbs);
	476	}
	477
	478	static void __exit cpufreq_gov_dbs_exit(void)
	479	{
	480	/* Make sure that the scheduled work is indeed not running */
	481	flush_scheduled_work();
	482
	483	cpufreq_unregister_governor(&cpufreq_gov_dbs);
	484	}
	485
	486
	487	MODULE_AUTHOR ("Venkatesh Pallipadi <venkatesh.pallipadi@intel.com>");
	488	MODULE_DESCRIPTION ("'cpufreq_ondemand' - A dynamic cpufreq governor for "
	489	"Low Latency Frequency Transition capable processors");
	490	MODULE_LICENSE ("GPL");
	491
	492	module_init(cpufreq_gov_dbs_init);
	493	module_exit(cpufreq_gov_dbs_exit);