ARM: Tegra: Added support to run at two frequency modes

CPU clock is now capped at an normal frequency that is below
its maximum and allowed to run at a high frequency
only once within a period of time. By default the delay is set to
5*DOWN_DELAY, allowing a maximum of 20% high frequency time.

Sysfs knobs were also added that allows userspace tuning

Bug 1003531

Change-Id: Ie4a0e565630187bdacd6f31b1f35778eb31bfc81
Signed-off-by: Xiao Bo Zhao <xiaoboz@nvidia.com>
Reviewed-on: http://git-master/r/118163
Reviewed-by: Peter Boonstoppel <pboonstoppel@nvidia.com>
Reviewed-by: Diwakar Tundlam <dtundlam@nvidia.com>
GVS: Gerrit_Virtual_Submit
Reviewed-by: Bharat Nihalani <bnihalani@nvidia.com>

1 files changed, 42 insertions, 2 deletions

diff --git a/drivers/cpufreq/cpufreq_interactive.c b/drivers/cpufreq/cpufreq_interactive.c
index 798930ffe1f4..20a9b6d22156 100644
--- a/drivers/cpufreq/cpufreq_interactive.c
+++ b/drivers/cpufreq/cpufreq_interactive.c
@@ -43,6 +43,7 @@ struct cpufreq_interactive_cpuinfo {
 	u64 freq_change_time;
 	u64 freq_change_time_in_idle;
 	u64 freq_change_time_in_iowait;
+	u64 last_high_freq_time;
 	struct cpufreq_policy *policy;
 	struct cpufreq_frequency_table *freq_table;
 	unsigned int target_freq;
@@ -92,6 +93,24 @@ static unsigned long min_sample_time;
 #define DEFAULT_TIMER_RATE 20000;
 static unsigned long timer_rate;
 
+/*
+ * The minimum delay before frequency is allowed to raise over normal rate.
+ * Since it must remain at high frequency for a minimum of MIN_SAMPLE_TIME
+ * once it rises, setting this delay to a multiple of MIN_SAMPLE_TIME
+ * becomes the best way to enforce a square wave.
+ * e.g. 5*MIN_SAMPLE_TIME = 20% high freq duty cycle
+ */
+#define DEFAULT_HIGH_FREQ_MIN_DELAY 5*DEFAULT_MIN_SAMPLE_TIME
+static unsigned long high_freq_min_delay;
+
+/*
+ * The maximum frequency CPUs are allowed to run normally
+ * 0 if disabled
+ */
+#define DEFAULT_MAX_NORMAL_FREQ 0
+static unsigned long max_normal_freq;
+
+
 /* Defines to control mid-range frequencies */
 #define DEFAULT_MID_RANGE_GO_MAXSPEED_LOAD 95
 
@@ -274,6 +293,20 @@ static void cpufreq_interactive_timer(unsigned long data)
 			goto rearm;
 	}
 
+	/*
+	 * Can only overclock if the delay is satisfy. Otherwise, cap it to
+	 * maximum allowed normal frequency
+	 */
+	if (max_normal_freq && (new_freq > max_normal_freq)) {
+		if (cputime64_sub(pcpu->timer_run_time, pcpu->last_high_freq_time)
+				< high_freq_min_delay) {
+			new_freq = max_normal_freq;
+		}
+		else {
+			pcpu->last_high_freq_time = pcpu->timer_run_time;
+		}
+	}
+
 	if (new_freq < pcpu->target_freq) {
 		pcpu->target_freq = new_freq;
 		spin_lock_irqsave(&down_cpumask_lock, flags);
@@ -552,7 +585,9 @@ DECL_CPUFREQ_INTERACTIVE_ATTR(max_boost)
 DECL_CPUFREQ_INTERACTIVE_ATTR(midrange_max_boost)
 DECL_CPUFREQ_INTERACTIVE_ATTR(sustain_load)
 DECL_CPUFREQ_INTERACTIVE_ATTR(min_sample_time)
-DECL_CPUFREQ_INTERACTIVE_ATTR(timer_rate);
+DECL_CPUFREQ_INTERACTIVE_ATTR(timer_rate)
+DECL_CPUFREQ_INTERACTIVE_ATTR(high_freq_min_delay)
+DECL_CPUFREQ_INTERACTIVE_ATTR(max_normal_freq)
 
 #undef DECL_CPUFREQ_INTERACTIVE_ATTR
 
@@ -567,6 +602,8 @@ static struct attribute *interactive_attributes[] = {
 	&sustain_load_attr.attr,
 	&min_sample_time_attr.attr,
 	&timer_rate_attr.attr,
+	&high_freq_min_delay_attr.attr,
+	&max_normal_freq_attr.attr,
 	NULL,
 };
 
@@ -604,7 +641,8 @@ static int cpufreq_governor_interactive(struct cpufreq_policy *policy,
 			pcpu->freq_change_time_in_iowait =
 				get_cpu_iowait_time(j, NULL);
 			pcpu->time_in_iowait = pcpu->freq_change_time_in_iowait;
-
+			if (!pcpu->last_high_freq_time)
+				pcpu->last_high_freq_time = pcpu->freq_change_time;
 			pcpu->timer_idlecancel = 1;
 			pcpu->governor_enabled = 1;
 			smp_wmb();
@@ -694,6 +732,8 @@ static int __init cpufreq_interactive_init(void)
 	midrange_go_maxspeed_load = DEFAULT_MID_RANGE_GO_MAXSPEED_LOAD;
 	min_sample_time = DEFAULT_MIN_SAMPLE_TIME;
 	timer_rate = DEFAULT_TIMER_RATE;
+	high_freq_min_delay = DEFAULT_HIGH_FREQ_MIN_DELAY;
+	max_normal_freq = DEFAULT_MAX_NORMAL_FREQ;
 
 	/* Initalize per-cpu timers */
 	for_each_possible_cpu(i) {