1 files changed, 284 insertions, 9 deletions

diff --git a/drivers/cpuidle/lpm-levels.c b/drivers/cpuidle/lpm-levels.c
index 389e49ef8fca..ced95aa2b649 100644
--- a/drivers/cpuidle/lpm-levels.c
+++ b/drivers/cpuidle/lpm-levels.c
@@ -1,4 +1,6 @@
 /* Copyright (c) 2012-2016, The Linux Foundation. All rights reserved.
+ * Copyright (C) 2006-2007 Adam Belay <abelay@novell.com>
+ * Copyright (C) 2009 Intel Corporation
  *
  * This program is free software; you can redistribute it and/or modify
  * it under the terms of the GNU General Public License version 2 and
@@ -83,9 +85,37 @@ struct lpm_debug {
 
 struct lpm_cluster *lpm_root_node;
 
+#define MAXSAMPLES 5
+
+static bool lpm_prediction;
+module_param_named(lpm_prediction,
+	lpm_prediction, bool, S_IRUGO | S_IWUSR | S_IWGRP);
+
+static uint32_t ref_stddev = 100;
+module_param_named(
+	ref_stddev, ref_stddev, uint, S_IRUGO | S_IWUSR | S_IWGRP
+);
+
+static uint32_t tmr_add = 100;
+module_param_named(
+	tmr_add, tmr_add, uint, S_IRUGO | S_IWUSR | S_IWGRP
+);
+
+struct lpm_history {
+	uint32_t resi[MAXSAMPLES];
+	int mode[MAXSAMPLES];
+	int nsamp;
+	uint32_t hptr;
+	uint32_t hinvalid;
+	uint32_t htmr_wkup;
+};
+
+static DEFINE_PER_CPU(struct lpm_history, hist);
+
 static DEFINE_PER_CPU(struct lpm_cluster*, cpu_cluster);
 static bool suspend_in_progress;
 static struct hrtimer lpm_hrtimer;
+static struct hrtimer histtimer;
 static struct lpm_debug *lpm_debug;
 static phys_addr_t lpm_debug_phys;
 static const int num_dbg_elements = 0x100;
@@ -327,10 +357,37 @@ static enum hrtimer_restart lpm_hrtimer_cb(struct hrtimer *h)
 	return HRTIMER_NORESTART;
 }
 
+static void histtimer_cancel(void)
+{
+	if (!lpm_prediction)
+		return;
+
+	hrtimer_try_to_cancel(&histtimer);
+}
+
+static enum hrtimer_restart histtimer_fn(struct hrtimer *h)
+{
+	int cpu = raw_smp_processor_id();
+	struct lpm_history *history = &per_cpu(hist, cpu);
+
+	history->hinvalid = 1;
+	return HRTIMER_NORESTART;
+}
+
+static void histtimer_start(uint32_t time_us)
+{
+	uint64_t time_ns = time_us * NSEC_PER_USEC;
+	ktime_t hist_ktime = ns_to_ktime(time_ns);
+
+	histtimer.function = histtimer_fn;
+	hrtimer_start(&histtimer, hist_ktime, HRTIMER_MODE_REL_PINNED);
+}
+
 static void msm_pm_set_timer(uint32_t modified_time_us)
 {
 	u64 modified_time_ns = modified_time_us * NSEC_PER_USEC;
 	ktime_t modified_ktime = ns_to_ktime(modified_time_ns);
+
 	lpm_hrtimer.function = lpm_hrtimer_cb;
 	hrtimer_start(&lpm_hrtimer, modified_ktime, HRTIMER_MODE_REL_PINNED);
 }
@@ -415,6 +472,143 @@ static int set_device_mode(struct lpm_cluster *cluster, int ndevice,
 		return -EINVAL;
 }
 
+static uint64_t lpm_cpuidle_predict(struct cpuidle_device *dev,
+		struct lpm_cpu *cpu, int *idx_restrict,
+		uint32_t *idx_restrict_time)
+{
+	int i, j, divisor;
+	uint64_t max, avg, stddev;
+	int64_t thresh = LLONG_MAX;
+	struct lpm_history *history = &per_cpu(hist, dev->cpu);
+	uint32_t *min_residency = get_per_cpu_min_residency(dev->cpu);
+
+	if (!lpm_prediction)
+		return 0;
+
+	/*
+	 * Samples are marked invalid when woken-up due to timer,
+	 * so donot predict.
+	 */
+	if (history->hinvalid) {
+		history->hinvalid = 0;
+		history->htmr_wkup = 1;
+		return 0;
+	}
+
+	/*
+	 * Predict only when all the samples are collected.
+	 */
+	if (history->nsamp < MAXSAMPLES)
+		return 0;
+
+	/*
+	 * Check if the samples are not much deviated, if so use the
+	 * average of those as predicted sleep time. Else if any
+	 * specific mode has more premature exits return the index of
+	 * that mode.
+	 */
+
+again:
+	max = avg = divisor = stddev = 0;
+	for (i = 0; i < MAXSAMPLES; i++) {
+		int64_t value = history->resi[i];
+
+		if (value <= thresh) {
+			avg += value;
+			divisor++;
+			if (value > max)
+				max = value;
+		}
+	}
+	do_div(avg, divisor);
+
+	for (i = 0; i < MAXSAMPLES; i++) {
+		int64_t value = history->resi[i];
+
+		if (value <= thresh) {
+			int64_t diff = value - avg;
+
+			stddev += diff * diff;
+		}
+	}
+	do_div(stddev, divisor);
+	stddev = int_sqrt(stddev);
+
+	/*
+	 * If the deviation is less, return the average, else
+	 * ignore one maximum sample and retry
+	 */
+	if (((avg > stddev * 6) && (divisor >= (MAXSAMPLES - 1)))
+					|| stddev <= ref_stddev) {
+		return avg;
+	} else if (divisor  > (MAXSAMPLES - 1)) {
+		thresh = max - 1;
+		goto again;
+	}
+
+	/*
+	 * Find the number of premature exits for each of the mode,
+	 * excluding clockgating mode, and they are more than fifty
+	 * percent restrict that and deeper modes.
+	 */
+	if (history->htmr_wkup != 1) {
+		for (j = 1; j < cpu->nlevels; j++) {
+			uint32_t failed = 0;
+			uint64_t total = 0;
+
+			for (i = 0; i < MAXSAMPLES; i++) {
+				if ((history->mode[i] == j) &&
+					(history->resi[i] < min_residency[j])) {
+					failed++;
+					total += history->resi[i];
+				}
+			}
+			if (failed > (MAXSAMPLES/2)) {
+				*idx_restrict = j;
+				do_div(total, failed);
+				*idx_restrict_time = total;
+				break;
+			}
+		}
+	}
+	return 0;
+}
+
+static inline void invalidate_predict_history(struct cpuidle_device *dev)
+{
+	struct lpm_history *history = &per_cpu(hist, dev->cpu);
+
+	if (!lpm_prediction)
+		return;
+
+	if (history->hinvalid) {
+		history->hinvalid = 0;
+		history->htmr_wkup = 1;
+	}
+}
+
+static void clear_predict_history(void)
+{
+	struct lpm_history *history;
+	int i;
+	unsigned int cpu;
+
+	if (!lpm_prediction)
+		return;
+
+	for_each_possible_cpu(cpu) {
+		history = &per_cpu(hist, cpu);
+		for (i = 0; i < MAXSAMPLES; i++) {
+			history->resi[i]  = 0;
+			history->mode[i] = -1;
+			history->hptr = 0;
+			history->nsamp = 0;
+		}
+	}
+}
+
+static void update_history(struct cpuidle_device *dev, int idx);
+
 static int cpu_power_select(struct cpuidle_device *dev,
 		struct lpm_cpu *cpu)
 {
@@ -425,9 +619,13 @@ static int cpu_power_select(struct cpuidle_device *dev,
 		(uint32_t)(ktime_to_us(tick_nohz_get_sleep_length()));
 	uint32_t modified_time_us = 0;
 	uint32_t next_event_us = 0;
-	int i;
+	int i, idx_restrict;
 	uint32_t lvl_latency_us = 0;
-	uint32_t *residency = get_per_cpu_max_residency(dev->cpu);
+	uint64_t predicted = 0;
+	uint32_t htime = 0, idx_restrict_time = 0;
+	uint32_t next_wakeup_us = sleep_us;
+	uint32_t *min_residency = get_per_cpu_min_residency(dev->cpu);
+	uint32_t *max_residency = get_per_cpu_max_residency(dev->cpu);
 
 	if (!cpu)
 		return -EINVAL;
@@ -435,12 +633,13 @@ static int cpu_power_select(struct cpuidle_device *dev,
 	if (sleep_disabled)
 		return 0;
 
+	idx_restrict = cpu->nlevels + 1;
+
 	next_event_us = (uint32_t)(ktime_to_us(get_next_event_time(dev->cpu)));
 
 	for (i = 0; i < cpu->nlevels; i++) {
 		struct lpm_cpu_level *level = &cpu->levels[i];
 		struct power_params *pwr_params = &level->pwr;
-		uint32_t next_wakeup_us = sleep_us;
 		enum msm_pm_sleep_mode mode = level->mode;
 		bool allow;
 
@@ -463,24 +662,64 @@ static int cpu_power_select(struct cpuidle_device *dev,
 				next_wakeup_us = next_event_us - lvl_latency_us;
 		}
 
+		if (!i) {
+			/*
+			 * If the next_wake_us itself is not sufficient for
+			 * deeper low power modes than clock gating do not
+			 * call prediction.
+			 */
+			if (next_wakeup_us > max_residency[i]) {
+				predicted = lpm_cpuidle_predict(dev, cpu,
+					&idx_restrict, &idx_restrict_time);
+				if (predicted < min_residency[i])
+					predicted = 0;
+			} else
+				invalidate_predict_history(dev);
+		}
+
+		if (i >= idx_restrict)
+			break;
+
 		best_level = i;
 
 		if (next_event_us && next_event_us < sleep_us &&
-				(mode != MSM_PM_SLEEP_MODE_WAIT_FOR_INTERRUPT))
+			(mode != MSM_PM_SLEEP_MODE_WAIT_FOR_INTERRUPT))
 			modified_time_us
 				= next_event_us - lvl_latency_us;
 		else
 			modified_time_us = 0;
 
-		if (next_wakeup_us <= residency[i])
+		if (predicted ? (predicted <= max_residency[i])
+			: (next_wakeup_us <= max_residency[i]))
 			break;
 	}
 
 	if (modified_time_us)
 		msm_pm_set_timer(modified_time_us);
 
+	/*
+	 * Start timer to avoid staying in shallower mode forever
+	 * incase of misprediciton
+	 */
+	if ((predicted || (idx_restrict != (cpu->nlevels + 1)))
+			&& ((best_level >= 0)
+			&& (best_level < (cpu->nlevels-1)))) {
+		htime = predicted + tmr_add;
+		if (htime == tmr_add)
+			htime = idx_restrict_time;
+		else if (htime > max_residency[best_level])
+			htime = max_residency[best_level];
+
+		if ((next_wakeup_us > htime) &&
+			((next_wakeup_us - htime) > max_residency[best_level]))
+			histtimer_start(htime);
+	}
+
 	trace_cpu_power_select(best_level, sleep_us, latency_us, next_event_us);
 
+	trace_cpu_pred_select(idx_restrict_time ? 2 : (predicted ? 1 : 0),
+			predicted, htime);
+
 	return best_level;
 }
 
@@ -641,6 +880,7 @@ static int cluster_configure(struct lpm_cluster *cluster, int idx,
 		}
 
 		us = us + 1;
+		clear_predict_history();
 		do_div(us, USEC_PER_SEC/SCLK_HZ);
 		msm_mpm_enter_sleep(us, from_idle, cpumask);
 	}
@@ -975,6 +1215,39 @@ static int lpm_cpuidle_select(struct cpuidle_driver *drv,
 	return idx;
 }
 
+static void update_history(struct cpuidle_device *dev, int idx)
+{
+	struct lpm_history *history = &per_cpu(hist, dev->cpu);
+	uint32_t tmr = 0;
+
+	if (!lpm_prediction)
+		return;
+
+	if (history->htmr_wkup) {
+		if (!history->hptr)
+			history->hptr = MAXSAMPLES-1;
+		else
+			history->hptr--;
+
+		history->resi[history->hptr] += dev->last_residency;
+		history->htmr_wkup = 0;
+		tmr = 1;
+	} else
+		history->resi[history->hptr] = dev->last_residency;
+
+	history->mode[history->hptr] = idx;
+
+	trace_cpu_pred_hist(history->mode[history->hptr],
+		history->resi[history->hptr], history->hptr, tmr);
+
+	if (history->nsamp < MAXSAMPLES)
+		history->nsamp++;
+
+	(history->hptr)++;
+	if (history->hptr >= MAXSAMPLES)
+		history->hptr = 0;
+}
+
 static int lpm_cpuidle_enter(struct cpuidle_device *dev,
 		struct cpuidle_driver *drv, int idx)
 {
@@ -1009,12 +1282,13 @@ exit:
 	cluster_unprepare(cluster, cpumask, idx, true, end_time);
 	cpu_unprepare(cluster, idx, true);
 	sched_set_cpu_cstate(smp_processor_id(), 0, 0, 0);
-
-	trace_cpu_idle_exit(idx, success);
 	end_time = ktime_to_ns(ktime_get()) - start_time;
-	dev->last_residency = do_div(end_time, 1000);
+	do_div(end_time, 1000);
+	dev->last_residency = end_time;
+	update_history(dev, idx);
+	trace_cpu_idle_exit(idx, success);
 	local_irq_enable();
-
+	histtimer_cancel();
 	return idx;
 }
 
@@ -1286,6 +1560,7 @@ static int lpm_probe(struct platform_device *pdev)
 	 */
 	suspend_set_ops(&lpm_suspend_ops);
 	hrtimer_init(&lpm_hrtimer, CLOCK_MONOTONIC, HRTIMER_MODE_REL);
+	hrtimer_init(&histtimer, CLOCK_MONOTONIC, HRTIMER_MODE_REL);
 
 	ret = remote_spin_lock_init(&scm_handoff_lock, SCM_HANDOFF_LOCK_ID);
 	if (ret) {