cpufreq: interactive: add sysfs control for timer rate

Add a new sysfs control that tunes the rate of the timer used to
increase cpu frequency

Change-Id: I1aa13ae54bb43aff5b3688984d2955f56aae1658
Signed-off-by: Allen Martin <amartin@nvidia.com>

drivers/cpufreq/cpufreq_interactive.c

@@ -66,6 +66,12 @@ static unsigned long go_maxspeed_load;
 #define DEFAULT_MIN_SAMPLE_TIME 80000;
 static unsigned long min_sample_time;
 
+/*
+ * The sample rate of the timer used to increase frequency
+ */
+#define DEFAULT_TIMER_RATE 30000;
+static unsigned long timer_rate;
+
 static int cpufreq_governor_interactive(struct cpufreq_policy *policy,
 		unsigned int event);
 
@@ -219,7 +225,7 @@ static void cpufreq_interactive_timer(unsigned long data)
 
 		pcpu->time_in_idle = get_cpu_idle_time_us(
 			data, &pcpu->idle_exit_time);
-		mod_timer(&pcpu->cpu_timer, jiffies + 2);
+		mod_timer(&pcpu->cpu_timer, jiffies + usecs_to_jiffies(timer_rate));
 	}
 
 exit:
@@ -254,7 +260,7 @@ static void cpufreq_interactive_idle_start(void)
 			pcpu->time_in_idle = get_cpu_idle_time_us(
 				smp_processor_id(), &pcpu->idle_exit_time);
 			pcpu->timer_idlecancel = 0;
-			mod_timer(&pcpu->cpu_timer, jiffies + 2);
+			mod_timer(&pcpu->cpu_timer, jiffies + usecs_to_jiffies(timer_rate));
 		}
 #endif
 	} else {
@@ -304,7 +310,7 @@ static void cpufreq_interactive_idle_end(void)
 			get_cpu_idle_time_us(smp_processor_id(),
 					     &pcpu->idle_exit_time);
 		pcpu->timer_idlecancel = 0;
-		mod_timer(&pcpu->cpu_timer, jiffies + 2);
+		mod_timer(&pcpu->cpu_timer, jiffies + usecs_to_jiffies(timer_rate));
 	}
 
 }
@@ -429,9 +435,32 @@ static ssize_t store_min_sample_time(struct kobject *kobj,
 static struct global_attr min_sample_time_attr = __ATTR(min_sample_time, 0644,
 		show_min_sample_time, store_min_sample_time);
 
+static ssize_t show_timer_rate(struct kobject *kobj,
+			struct attribute *attr, char *buf)
+{
+	return sprintf(buf, "%lu\n", timer_rate);
+}
+
+static ssize_t store_timer_rate(struct kobject *kobj,
+			struct attribute *attr, const char *buf, size_t count)
+{
+	int ret;
+	unsigned long val;
+
+	ret = strict_strtoul(buf, 0, &val);
+	if (ret < 0)
+		return ret;
+	timer_rate = val;
+	return count;
+}
+
+static struct global_attr timer_rate_attr = __ATTR(timer_rate, 0644,
+		show_timer_rate, store_timer_rate);
+
 static struct attribute *interactive_attributes[] = {
 	&go_maxspeed_load_attr.attr,
 	&min_sample_time_attr.attr,
+	&timer_rate_attr.attr,
 	NULL,
 };
 
@@ -547,6 +576,7 @@ static int __init cpufreq_interactive_init(void)
 
 	go_maxspeed_load = DEFAULT_GO_MAXSPEED_LOAD;
 	min_sample_time = DEFAULT_MIN_SAMPLE_TIME;
+	timer_rate = DEFAULT_TIMER_RATE;
 
 	/* Initalize per-cpu timers */
 	for_each_possible_cpu(i) {