cpufreq: Extend ondemand powersave_bias for negative range

Original ondemand powersave_bias parameter allows value
range from 0 (no powersave) to 1000 (100% reduction in
calculated CPU frequency).  This change extends powersave_bias
into the negative range (-1 to -1000) to allow a corresponding
boost to CPU frequency.  When set at either limit (-1000 or
1000), ondemand timer is cancelled as periodic load
sampling at sampling_rate is not necessary.

Change-Id: I2ee05729ceec20c2e2a4c6d9ca05cecd16ab161a
Signed-off-by: David Ng <dave@codeaurora.org>

drivers/cpufreq/cpufreq_ondemand.c

@@ -60,6 +60,9 @@ static unsigned int min_sampling_rate;
 #define MIN_LATENCY_MULTIPLIER			(100)
 #define TRANSITION_LATENCY_LIMIT		(10 * 1000 * 1000)
 
+#define POWERSAVE_BIAS_MAXLEVEL			(1000)
+#define POWERSAVE_BIAS_MINLEVEL			(-1000)
+
 static void do_dbs_timer(struct work_struct *work);
 static int cpufreq_governor_dbs(struct cpufreq_policy *policy,
 				unsigned int event);
@@ -100,6 +103,9 @@ struct cpu_dbs_info_s {
 };
 static DEFINE_PER_CPU(struct cpu_dbs_info_s, od_cpu_dbs_info);
 
+static inline void dbs_timer_init(struct cpu_dbs_info_s *dbs_info);
+static inline void dbs_timer_exit(struct cpu_dbs_info_s *dbs_info);
+
 static unsigned int dbs_enable;	/* number of CPUs using this policy */
 
 /*
@@ -117,7 +123,7 @@ static struct dbs_tuners {
 	unsigned int down_differential;
 	unsigned int ignore_nice;
 	unsigned int sampling_down_factor;
-	unsigned int powersave_bias;
+	int          powersave_bias;
 	unsigned int io_is_busy;
 } dbs_tuners_ins = {
 	.up_threshold = DEF_FREQUENCY_UP_THRESHOLD,
@@ -179,10 +185,11 @@ static unsigned int powersave_bias_target(struct cpufreq_policy *policy,
 					  unsigned int freq_next,
 					  unsigned int relation)
 {
-	unsigned int freq_req, freq_reduc, freq_avg;
+	unsigned int freq_req, freq_avg;
 	unsigned int freq_hi, freq_lo;
 	unsigned int index = 0;
 	unsigned int jiffies_total, jiffies_hi, jiffies_lo;
+	int freq_reduc;
 	struct cpu_dbs_info_s *dbs_info = &per_cpu(od_cpu_dbs_info,
 						   policy->cpu);
 
@@ -225,6 +232,26 @@ static unsigned int powersave_bias_target(struct cpufreq_policy *policy,
 	return freq_hi;
 }
 
+static int ondemand_powersave_bias_setspeed(struct cpufreq_policy *policy,
+					    struct cpufreq_policy *altpolicy,
+					    int level)
+{
+	if (level == POWERSAVE_BIAS_MAXLEVEL) {
+		/* maximum powersave; set to lowest frequency */
+		__cpufreq_driver_target(policy,
+			(altpolicy) ? altpolicy->min : policy->min,
+			CPUFREQ_RELATION_L);
+		return 1;
+	} else if (level == POWERSAVE_BIAS_MINLEVEL) {
+		/* minimum powersave; set to highest frequency */
+		__cpufreq_driver_target(policy,
+			(altpolicy) ? altpolicy->max : policy->max,
+			CPUFREQ_RELATION_H);
+		return 1;
+	}
+	return 0;
+}
+
 static void ondemand_powersave_bias_init_cpu(int cpu)
 {
 	struct cpu_dbs_info_s *dbs_info = &per_cpu(od_cpu_dbs_info, cpu);
@@ -263,7 +290,12 @@ show_one(up_threshold, up_threshold);
 show_one(down_differential, down_differential);
 show_one(sampling_down_factor, sampling_down_factor);
 show_one(ignore_nice_load, ignore_nice);
-show_one(powersave_bias, powersave_bias);
+
+static ssize_t show_powersave_bias
+(struct kobject *kobj, struct attribute *attr, char *buf)
+{
+	return snprintf(buf, PAGE_SIZE, "%d\n", dbs_tuners_ins.powersave_bias);
+}
 
 static ssize_t store_sampling_rate(struct kobject *a, struct attribute *b,
 				   const char *buf, size_t count)
@@ -378,18 +410,75 @@ static ssize_t store_ignore_nice_load(struct kobject *a, struct attribute *b,
 static ssize_t store_powersave_bias(struct kobject *a, struct attribute *b,
 				    const char *buf, size_t count)
 {
-	unsigned int input;
+	int input  = 0;
-	int ret;
+	int bypass = 0;
-	ret = sscanf(buf, "%u", &input);
+	int ret, cpu, reenable_timer;
+	struct cpu_dbs_info_s *dbs_info;
+
+	ret = sscanf(buf, "%d", &input);
 
 	if (ret != 1)
 		return -EINVAL;
 
-	if (input > 1000)
+	if (input >= POWERSAVE_BIAS_MAXLEVEL) {
-		input = 1000;
+		input  = POWERSAVE_BIAS_MAXLEVEL;
+		bypass = 1;
+	} else if (input <= POWERSAVE_BIAS_MINLEVEL) {
+		input  = POWERSAVE_BIAS_MINLEVEL;
+		bypass = 1;
+	}
+
+	if (input == dbs_tuners_ins.powersave_bias) {
+		/* no change */
+		return count;
+	}
+
+	reenable_timer = ((dbs_tuners_ins.powersave_bias ==
+				POWERSAVE_BIAS_MAXLEVEL) ||
+				(dbs_tuners_ins.powersave_bias ==
+				POWERSAVE_BIAS_MINLEVEL));
 
 	dbs_tuners_ins.powersave_bias = input;
-	ondemand_powersave_bias_init();
+	if (!bypass) {
+		if (reenable_timer) {
+			/* reinstate dbs timer */
+			for_each_online_cpu(cpu) {
+				if (lock_policy_rwsem_write(cpu) < 0)
+					continue;
+
+				dbs_info = &per_cpu(od_cpu_dbs_info, cpu);
+				if (dbs_info->cur_policy) {
+					/* restart dbs timer */
+					dbs_timer_init(dbs_info);
+				}
+				unlock_policy_rwsem_write(cpu);
+			}
+		}
+		ondemand_powersave_bias_init();
+	} else {
+		/* running at maximum or minimum frequencies; cancel
+		   dbs timer as periodic load sampling is not necessary */
+		for_each_online_cpu(cpu) {
+			if (lock_policy_rwsem_write(cpu) < 0)
+				continue;
+
+			dbs_info = &per_cpu(od_cpu_dbs_info, cpu);
+			if (dbs_info->cur_policy) {
+				/* cpu using ondemand, cancel dbs timer */
+				mutex_lock(&dbs_info->timer_mutex);
+				dbs_timer_exit(dbs_info);
+
+				ondemand_powersave_bias_setspeed(
+					dbs_info->cur_policy,
+					NULL,
+					input);
+
+				mutex_unlock(&dbs_info->timer_mutex);
+			}
+			unlock_policy_rwsem_write(cpu);
+		}
+	}
+
 	return count;
 }
 
@@ -680,6 +769,12 @@ static void dbs_input_event(struct input_handle *handle, unsigned int type,
 {
 	int i;
 
+	if ((dbs_tuners_ins.powersave_bias == POWERSAVE_BIAS_MAXLEVEL) ||
+		(dbs_tuners_ins.powersave_bias == POWERSAVE_BIAS_MINLEVEL)) {
+		/* nothing to do */
+		return;
+	}
+
 	for_each_online_cpu(i) {
 		queue_work_on(i, input_wq, &per_cpu(dbs_refresh_work, i));
 	}
@@ -799,7 +894,12 @@ static int cpufreq_governor_dbs(struct cpufreq_policy *policy,
 		mutex_unlock(&dbs_mutex);
 
 		mutex_init(&this_dbs_info->timer_mutex);
-		dbs_timer_init(this_dbs_info);
+
+		if (!ondemand_powersave_bias_setspeed(
+					this_dbs_info->cur_policy,
+					NULL,
+					dbs_tuners_ins.powersave_bias))
+			dbs_timer_init(this_dbs_info);
 		break;
 
 	case CPUFREQ_GOV_STOP:
@@ -828,6 +928,11 @@ static int cpufreq_governor_dbs(struct cpufreq_policy *policy,
 		else if (policy->min > this_dbs_info->cur_policy->cur)
 			__cpufreq_driver_target(this_dbs_info->cur_policy,
 				policy->min, CPUFREQ_RELATION_L);
+		else if (dbs_tuners_ins.powersave_bias != 0)
+			ondemand_powersave_bias_setspeed(
+				this_dbs_info->cur_policy,
+				policy,
+				dbs_tuners_ins.powersave_bias);
 		mutex_unlock(&this_dbs_info->timer_mutex);
 		break;
 	}