6 files changed, 736 insertions, 110 deletions

diff --git a/drivers/cpufreq/Kconfig b/drivers/cpufreq/Kconfig
index 95882bb1950e..60c9be99c6d9 100644
--- a/drivers/cpufreq/Kconfig
+++ b/drivers/cpufreq/Kconfig
@@ -46,6 +46,10 @@ config CPU_FREQ_STAT_DETAILS
          This will show detail CPU frequency translation table in sysfs file
          system
 
+# Note that it is not currently possible to set the other governors (such as ondemand)
+# as the default, since if they fail to initialise, cpufreq will be
+# left in an undefined state.
+
 choice
         prompt "Default CPUFreq governor"
         default CPU_FREQ_DEFAULT_GOV_USERSPACE if CPU_FREQ_SA1100 || CPU_FREQ_SA1110
@@ -115,4 +119,24 @@ config CPU_FREQ_GOV_ONDEMAND
 
           If in doubt, say N.
 
+config CPU_FREQ_GOV_CONSERVATIVE
+        tristate "'conservative' cpufreq governor"
+        depends on CPU_FREQ
+        help
+          'conservative' - this driver is rather similar to the 'ondemand'
+          governor both in its source code and its purpose, the difference is
+          its optimisation for better suitability in a battery powered
+          environment.  The frequency is gracefully increased and decreased
+          rather than jumping to 100% when speed is required.
+
+          If you have a desktop machine then you should really be considering
+          the 'ondemand' governor instead, however if you are using a laptop,
+          PDA or even an AMD64 based computer (due to the unacceptable
+          step-by-step latency issues between the minimum and maximum frequency
+          transitions in the CPU) you will probably want to use this governor.
+
+          For details, take a look at linux/Documentation/cpu-freq.
+
+          If in doubt, say N.
+
 endif   # CPU_FREQ
diff --git a/drivers/cpufreq/Makefile b/drivers/cpufreq/Makefile
index 67b16e5a41a7..71fc3b4173f1 100644
--- a/drivers/cpufreq/Makefile
+++ b/drivers/cpufreq/Makefile
@@ -8,6 +8,7 @@ obj-$(CONFIG_CPU_FREQ_GOV_PERFORMANCE)	+= cpufreq_performance.o
 obj-$(CONFIG_CPU_FREQ_GOV_POWERSAVE)    += cpufreq_powersave.o
 obj-$(CONFIG_CPU_FREQ_GOV_USERSPACE)    += cpufreq_userspace.o
 obj-$(CONFIG_CPU_FREQ_GOV_ONDEMAND)     += cpufreq_ondemand.o
+obj-$(CONFIG_CPU_FREQ_GOV_CONSERVATIVE) += cpufreq_conservative.o
 
 # CPUfreq cross-arch helpers
 obj-$(CONFIG_CPU_FREQ_TABLE)            += freq_table.o
diff --git a/drivers/cpufreq/cpufreq.c b/drivers/cpufreq/cpufreq.c
index 8e561313d094..03b5fb2ddcf4 100644
--- a/drivers/cpufreq/cpufreq.c
+++ b/drivers/cpufreq/cpufreq.c
@@ -258,7 +258,7 @@ void cpufreq_notify_transition(struct cpufreq_freqs *freqs, unsigned int state)
                             (likely(cpufreq_cpu_data[freqs->cpu]->cur)) &&
                             (unlikely(freqs->old != cpufreq_cpu_data[freqs->cpu]->cur)))
                         {
-                                printk(KERN_WARNING "Warning: CPU frequency is %u, "
+                                dprintk(KERN_WARNING "Warning: CPU frequency is %u, "
                                        "cpufreq assumed %u kHz.\n", freqs->old, cpufreq_cpu_data[freqs->cpu]->cur);
                                 freqs->old = cpufreq_cpu_data[freqs->cpu]->cur;
                         }
@@ -814,7 +814,7 @@ static void cpufreq_out_of_sync(unsigned int cpu, unsigned int old_freq, unsigne
 {
         struct cpufreq_freqs freqs;
 
-        printk(KERN_WARNING "Warning: CPU frequency out of sync: cpufreq and timing "
+        dprintk(KERN_WARNING "Warning: CPU frequency out of sync: cpufreq and timing "
                "core thinks of %u, is %u kHz.\n", old_freq, new_freq);
 
         freqs.cpu = cpu;
@@ -923,7 +923,7 @@ static int cpufreq_suspend(struct sys_device * sysdev, u32 state)
                 struct cpufreq_freqs freqs;
 
                 if (!(cpufreq_driver->flags & CPUFREQ_PM_NO_WARN))
-                        printk(KERN_DEBUG "Warning: CPU frequency is %u, "
+                        dprintk(KERN_DEBUG "Warning: CPU frequency is %u, "
                                "cpufreq assumed %u kHz.\n",
                                cur_freq, cpu_policy->cur);
 
@@ -1004,7 +1004,7 @@ static int cpufreq_resume(struct sys_device * sysdev)
                         struct cpufreq_freqs freqs;
 
                         if (!(cpufreq_driver->flags & CPUFREQ_PM_NO_WARN))
-                                printk(KERN_WARNING "Warning: CPU frequency"
+                                dprintk(KERN_WARNING "Warning: CPU frequency"
                                        "is %u, cpufreq assumed %u kHz.\n",
                                        cur_freq, cpu_policy->cur);
 
diff --git a/drivers/cpufreq/cpufreq_conservative.c b/drivers/cpufreq/cpufreq_conservative.c
new file mode 100644
index 000000000000..e1df376e709e
--- /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);
diff --git a/drivers/cpufreq/cpufreq_ondemand.c b/drivers/cpufreq/cpufreq_ondemand.c
index 8d83a21c6477..c1fc9c62bb51 100644
--- a/drivers/cpufreq/cpufreq_ondemand.c
+++ b/drivers/cpufreq/cpufreq_ondemand.c
@@ -34,13 +34,9 @@
  */
 
 #define DEF_FREQUENCY_UP_THRESHOLD              (80)
-#define MIN_FREQUENCY_UP_THRESHOLD              (0)
+#define MIN_FREQUENCY_UP_THRESHOLD              (11)
 #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
@@ -55,9 +51,9 @@ 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                (10)
+#define DEF_SAMPLING_DOWN_FACTOR                (1)
+#define MAX_SAMPLING_DOWN_FACTOR                (10)
 #define TRANSITION_LATENCY_LIMIT                (10 * 1000)
-#define sampling_rate_in_HZ(x)                  (((x * HZ) < (1000 * 1000))?1:((x * HZ) / (1000 * 1000)))
 
 static void do_dbs_timer(void *data);
 
@@ -78,15 +74,23 @@ struct dbs_tuners {
         unsigned int            sampling_rate;
         unsigned int            sampling_down_factor;
         unsigned int            up_threshold;
-        unsigned int            down_threshold;
+        unsigned int            ignore_nice;
 };
 
 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)
 {
@@ -115,7 +119,7 @@ static ssize_t show_##file_name						\
 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);
 
 static ssize_t store_sampling_down_factor(struct cpufreq_policy *unused, 
                 const char *buf, size_t count)
@@ -126,6 +130,9 @@ static ssize_t store_sampling_down_factor(struct cpufreq_policy *unused,
         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);
@@ -161,8 +168,7 @@ static ssize_t store_up_threshold(struct cpufreq_policy *unused,
 
         down(&dbs_sem);
         if (ret != 1 || input > MAX_FREQUENCY_UP_THRESHOLD || 
-                        input < MIN_FREQUENCY_UP_THRESHOLD ||
-                        input <= dbs_tuners_ins.down_threshold) {
+                        input < MIN_FREQUENCY_UP_THRESHOLD) {
                 up(&dbs_sem);
                 return -EINVAL;
         }
@@ -173,22 +179,35 @@ static ssize_t store_up_threshold(struct cpufreq_policy *unused,
         return count;
 }
 
-static ssize_t store_down_threshold(struct cpufreq_policy *unused, 
+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 (ret != 1 || input > MAX_FREQUENCY_DOWN_THRESHOLD || 
-                        input < MIN_FREQUENCY_DOWN_THRESHOLD ||
-                        input >= dbs_tuners_ins.up_threshold) {
+        if ( input == dbs_tuners_ins.ignore_nice ) { /* nothing to do */
                 up(&dbs_sem);
-                return -EINVAL;
+                return count;
         }
+        dbs_tuners_ins.ignore_nice = input;
 
-        dbs_tuners_ins.down_threshold = 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;
@@ -201,7 +220,7 @@ __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);
 
 static struct attribute * dbs_attributes[] = {
         &sampling_rate_max.attr,
@@ -209,7 +228,7 @@ static struct attribute * dbs_attributes[] = {
         &sampling_rate.attr,
         &sampling_down_factor.attr,
         &up_threshold.attr,
-        &down_threshold.attr,
+        &ignore_nice.attr,
         NULL
 };
 
@@ -222,9 +241,8 @@ static struct attribute_group dbs_attr_group = {
 
 static void dbs_check_cpu(int cpu)
 {
-        unsigned int idle_ticks, up_idle_ticks, down_idle_ticks;
-        unsigned int total_idle_ticks;
-        unsigned int freq_down_step;
+        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;
@@ -238,38 +256,25 @@ static void dbs_check_cpu(int cpu)
 
         policy = this_dbs_info->cur_policy;
         /* 
-         * 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
+         * 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% of max_frequency 
+         * 5% (default) of current frequency 
          */
 
         /* Check for frequency increase */
-        total_idle_ticks = kstat_cpu(cpu).cpustat.idle +
-                kstat_cpu(cpu).cpustat.iowait;
-        idle_ticks = total_idle_ticks -
-                this_dbs_info->prev_cpu_idle_up;
-        this_dbs_info->prev_cpu_idle_up = total_idle_ticks;
-        
-
+        idle_ticks = UINT_MAX;
         for_each_cpu_mask(j, policy->cpus) {
-                unsigned int tmp_idle_ticks;
+                unsigned int tmp_idle_ticks, total_idle_ticks;
                 struct cpu_dbs_info_s *j_dbs_info;
 
-                if (j == cpu)
-                        continue;
-
                 j_dbs_info = &per_cpu(cpu_dbs_info, j);
-                /* Check for frequency increase */
-                total_idle_ticks = kstat_cpu(j).cpustat.idle +
-                        kstat_cpu(j).cpustat.iowait;
+                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;
@@ -281,13 +286,23 @@ static void dbs_check_cpu(int cpu)
         /* Scale idle ticks by 100 and compare with up and down ticks */
         idle_ticks *= 100;
         up_idle_ticks = (100 - dbs_tuners_ins.up_threshold) *
-                        sampling_rate_in_HZ(dbs_tuners_ins.sampling_rate);
+                        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);
-                down_skip[cpu] = 0;
-                this_dbs_info->prev_cpu_idle_down = total_idle_ticks;
                 return;
         }
 
@@ -296,23 +311,14 @@ static void dbs_check_cpu(int cpu)
         if (down_skip[cpu] < dbs_tuners_ins.sampling_down_factor)
                 return;
 
-        total_idle_ticks = kstat_cpu(cpu).cpustat.idle +
-                kstat_cpu(cpu).cpustat.iowait;
-        idle_ticks = total_idle_ticks -
-                this_dbs_info->prev_cpu_idle_down;
-        this_dbs_info->prev_cpu_idle_down = total_idle_ticks;
-
+        idle_ticks = UINT_MAX;
         for_each_cpu_mask(j, policy->cpus) {
-                unsigned int tmp_idle_ticks;
+                unsigned int tmp_idle_ticks, total_idle_ticks;
                 struct cpu_dbs_info_s *j_dbs_info;
 
-                if (j == cpu)
-                        continue;
-
                 j_dbs_info = &per_cpu(cpu_dbs_info, j);
-                /* Check for frequency increase */
-                total_idle_ticks = kstat_cpu(j).cpustat.idle +
-                        kstat_cpu(j).cpustat.iowait;
+                /* 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;
@@ -321,38 +327,37 @@ static void dbs_check_cpu(int cpu)
                         idle_ticks = tmp_idle_ticks;
         }
 
-        /* Scale idle ticks by 100 and compare with up and down ticks */
-        idle_ticks *= 100;
         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;
-        down_idle_ticks = (100 - dbs_tuners_ins.down_threshold) *
-                        sampling_rate_in_HZ(freq_down_sampling_rate);
+        total_ticks = usecs_to_jiffies(freq_down_sampling_rate);
 
-        if (idle_ticks > down_idle_ticks ) {
-                freq_down_step = (5 * policy->max) / 100;
-
-                /* max freq cannot be less than 100. But who knows.... */
-                if (unlikely(freq_down_step == 0))
-                        freq_down_step = 5;
+        /*
+         * 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);
 
-                __cpufreq_driver_target(policy,
-                        policy->cur - freq_down_step, 
-                        CPUFREQ_RELATION_H);
-                return;
-        }
+        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 (i = 0; i < NR_CPUS; i++)
-                if (cpu_online(i))
-                        dbs_check_cpu(i);
+        for_each_online_cpu(i)
+                dbs_check_cpu(i);
         schedule_delayed_work(&dbs_work, 
-                        sampling_rate_in_HZ(dbs_tuners_ins.sampling_rate));
+                        usecs_to_jiffies(dbs_tuners_ins.sampling_rate));
         up(&dbs_sem);
 } 
 
@@ -360,7 +365,7 @@ static inline void dbs_timer_init(void)
 {
         INIT_WORK(&dbs_work, do_dbs_timer, NULL);
         schedule_delayed_work(&dbs_work,
-                        sampling_rate_in_HZ(dbs_tuners_ins.sampling_rate));
+                        usecs_to_jiffies(dbs_tuners_ins.sampling_rate));
         return;
 }
 
@@ -397,12 +402,9 @@ static int cpufreq_governor_dbs(struct cpufreq_policy *policy,
                         j_dbs_info = &per_cpu(cpu_dbs_info, j);
                         j_dbs_info->cur_policy = policy;
                 
-                        j_dbs_info->prev_cpu_idle_up = 
-                                kstat_cpu(j).cpustat.idle +
-                                kstat_cpu(j).cpustat.iowait;
-                        j_dbs_info->prev_cpu_idle_down = 
-                                kstat_cpu(j).cpustat.idle +
-                                kstat_cpu(j).cpustat.iowait;
+                        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);
@@ -422,6 +424,7 @@ static int cpufreq_governor_dbs(struct cpufreq_policy *policy,
                         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();
                 }
@@ -461,12 +464,11 @@ static int cpufreq_governor_dbs(struct cpufreq_policy *policy,
         return 0;
 }
 
-struct cpufreq_governor cpufreq_gov_dbs = {
+static struct cpufreq_governor cpufreq_gov_dbs = {
         .name           = "ondemand",
         .governor       = cpufreq_governor_dbs,
         .owner          = THIS_MODULE,
 };
-EXPORT_SYMBOL(cpufreq_gov_dbs);
 
 static int __init cpufreq_gov_dbs_init(void)
 {
diff --git a/drivers/cpufreq/cpufreq_stats.c b/drivers/cpufreq/cpufreq_stats.c
index 2084593937c6..741b6b191e6a 100644
--- a/drivers/cpufreq/cpufreq_stats.c
+++ b/drivers/cpufreq/cpufreq_stats.c
@@ -19,6 +19,7 @@
 #include <linux/percpu.h>
 #include <linux/kobject.h>
 #include <linux/spinlock.h>
+#include <asm/cputime.h>
 
 static spinlock_t cpufreq_stats_lock;
 
@@ -29,20 +30,14 @@ static struct freq_attr _attr_##_name = {\
         .show = _show,\
 };
 
-static unsigned long
-delta_time(unsigned long old, unsigned long new)
-{
-        return (old > new) ? (old - new): (new + ~old + 1);
-}
-
 struct cpufreq_stats {
         unsigned int cpu;
         unsigned int total_trans;
-        unsigned long long last_time;
+        unsigned long long  last_time;
         unsigned int max_state;
         unsigned int state_num;
         unsigned int last_index;
-        unsigned long long *time_in_state;
+        cputime64_t *time_in_state;
         unsigned int *freq_table;
 #ifdef CONFIG_CPU_FREQ_STAT_DETAILS
         unsigned int *trans_table;
@@ -60,12 +55,16 @@ static int
 cpufreq_stats_update (unsigned int cpu)
 {
         struct cpufreq_stats *stat;
+        unsigned long long cur_time;
+
+        cur_time = get_jiffies_64();
         spin_lock(&cpufreq_stats_lock);
         stat = cpufreq_stats_table[cpu];
         if (stat->time_in_state)
-                stat->time_in_state[stat->last_index] +=
-                        delta_time(stat->last_time, jiffies);
-        stat->last_time = jiffies;
+                stat->time_in_state[stat->last_index] =
+                        cputime64_add(stat->time_in_state[stat->last_index],
+                                      cputime_sub(cur_time, stat->last_time));
+        stat->last_time = cur_time;
         spin_unlock(&cpufreq_stats_lock);
         return 0;
 }
@@ -90,8 +89,8 @@ show_time_in_state(struct cpufreq_policy *policy, char *buf)
                 return 0;
         cpufreq_stats_update(stat->cpu);
         for (i = 0; i < stat->state_num; i++) {
-                len += sprintf(buf + len, "%u %llu\n",
-                        stat->freq_table[i], stat->time_in_state[i]);
+                len += sprintf(buf + len, "%u %llu\n", stat->freq_table[i], 
+                        (unsigned long long)cputime64_to_clock_t(stat->time_in_state[i]));
         }
         return len;
 }
@@ -107,16 +106,30 @@ show_trans_table(struct cpufreq_policy *policy, char *buf)
         if(!stat)
                 return 0;
         cpufreq_stats_update(stat->cpu);
+        len += snprintf(buf + len, PAGE_SIZE - len, "   From  :    To\n");
+        len += snprintf(buf + len, PAGE_SIZE - len, "         : ");
+        for (i = 0; i < stat->state_num; i++) {
+                if (len >= PAGE_SIZE)
+                        break;
+                len += snprintf(buf + len, PAGE_SIZE - len, "%9u ",
+                                stat->freq_table[i]);
+        }
+        if (len >= PAGE_SIZE)
+                return len;
+
+        len += snprintf(buf + len, PAGE_SIZE - len, "\n");
+
         for (i = 0; i < stat->state_num; i++) {
                 if (len >= PAGE_SIZE)
                         break;
-                len += snprintf(buf + len, PAGE_SIZE - len, "%9u:\t",
+
+                len += snprintf(buf + len, PAGE_SIZE - len, "%9u: ",
                                 stat->freq_table[i]);
 
                 for (j = 0; j < stat->state_num; j++)   {
                         if (len >= PAGE_SIZE)
                                 break;
-                        len += snprintf(buf + len, PAGE_SIZE - len, "%u\t",
+                        len += snprintf(buf + len, PAGE_SIZE - len, "%9u ",
                                         stat->trans_table[i*stat->max_state+j]);
                 }
                 len += snprintf(buf + len, PAGE_SIZE - len, "\n");
@@ -197,7 +210,7 @@ cpufreq_stats_create_table (struct cpufreq_policy *policy,
                 count++;
         }
 
-        alloc_size = count * sizeof(int) + count * sizeof(long long);
+        alloc_size = count * sizeof(int) + count * sizeof(cputime64_t);
 
 #ifdef CONFIG_CPU_FREQ_STAT_DETAILS
         alloc_size += count * count * sizeof(int);
@@ -224,7 +237,7 @@ cpufreq_stats_create_table (struct cpufreq_policy *policy,
         }
         stat->state_num = j;
         spin_lock(&cpufreq_stats_lock);
-        stat->last_time = jiffies;
+        stat->last_time = get_jiffies_64();
         stat->last_index = freq_table_get_index(stat, policy->cur);
         spin_unlock(&cpufreq_stats_lock);
         cpufreq_cpu_put(data);