1 files changed, 586 insertions, 0 deletions

diff --git a/drivers/cpufreq/cpufreq_conservative.c b/drivers/cpufreq/cpufreq_conservative.c
new file mode 100644
index 00000000000..e1df376e709
--- /dev/null
+++ b/drivers/cpufreq/cpufreq_conservative.c
@@ -0,0 +1,586 @@
+/*
+ *  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, 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(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);
+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.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 ( /* NULL */; init_flag < NR_CPUS; init_flag++ ) {
+			dbs_info = &per_cpu(cpu_dbs_info, init_flag);
+			requested_freq[cpu] = 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);