// SPDX-License-Identifier: GPL-2.0-only
/*
 * Copyright (c) 2012, 2015-2021, The Linux Foundation. All rights reserved.
 */

/*
 * Scheduler hook for average runqueue determination
 */
#include <linux/module.h>
#include <linux/percpu.h>
#include <linux/hrtimer.h>
#include <linux/sched.h>
#include <linux/math64.h>

#include "walt.h"
#include "trace.h"

static DEFINE_PER_CPU(u64, nr_prod_sum);
static DEFINE_PER_CPU(u64, last_time);
static DEFINE_PER_CPU(u64, nr_big_prod_sum);
static DEFINE_PER_CPU(u64, nr);
static DEFINE_PER_CPU(u64, nr_max);

static DEFINE_PER_CPU(spinlock_t, nr_lock) = __SPIN_LOCK_UNLOCKED(nr_lock);
static s64 last_get_time;

static DEFINE_PER_CPU(atomic64_t, busy_hyst_end_time) = ATOMIC64_INIT(0);

static DEFINE_PER_CPU(u64, hyst_time);
static DEFINE_PER_CPU(u64, coloc_hyst_busy);
static DEFINE_PER_CPU(u64, coloc_hyst_time);
static DEFINE_PER_CPU(u64, util_hyst_time);

#define NR_THRESHOLD_PCT		40
#define MAX_RTGB_TIME (sysctl_sched_coloc_busy_hyst_max_ms * NSEC_PER_MSEC)

struct sched_avg_stats stats[WALT_NR_CPUS];
unsigned int cstats_util_pct[MAX_CLUSTERS];

/**
 * sched_get_cluster_util_pct
 * @return: provide the percentage of this cluter that was used in the
 *          previous window.
 *
 * This routine may be called any number of times as needed during
 * a window, but will always return the same result until window
 * rollover.
 */
unsigned int sched_get_cluster_util_pct(struct walt_sched_cluster *cluster)
{
	unsigned int cluster_util_pct = 0;

	if (cluster->id < MAX_CLUSTERS)
		cluster_util_pct = cstats_util_pct[cluster->id];

	return cluster_util_pct;
}

/**
 * sched_get_nr_running_avg
 * @return: Average nr_running, iowait and nr_big_tasks value since last poll.
 *	    Returns the avg * 100 to return up to two decimal points
 *	    of accuracy.
 *
 * Obtains the average nr_running value since the last poll.
 * This function may not be called concurrently with itself.
 *
 * It is assumed that this function is called at most once per window
 * rollover.
 */
struct sched_avg_stats *sched_get_nr_running_avg(void)
{
	int cpu;
	u64 curr_time = sched_clock();
	u64 period = curr_time - last_get_time;
	u64 tmp_nr, tmp_misfit;
	bool any_hyst_time = false;
	struct walt_sched_cluster *cluster;

	if (!period)
		goto done;

	/* read and reset nr_running counts */
	for_each_possible_cpu(cpu) {
		unsigned long flags;
		u64 diff;

		spin_lock_irqsave(&per_cpu(nr_lock, cpu), flags);
		curr_time = sched_clock();
		diff = curr_time - per_cpu(last_time, cpu);
		BUG_ON((s64)diff < 0);

		tmp_nr = per_cpu(nr_prod_sum, cpu);
		tmp_nr += per_cpu(nr, cpu) * diff;
		tmp_nr = div64_u64((tmp_nr * 100), period);

		tmp_misfit = per_cpu(nr_big_prod_sum, cpu);
		tmp_misfit += walt_big_64bit_tasks(cpu) * diff;
		tmp_misfit = div64_u64((tmp_misfit * 100), period);

		/*
		 * NR_THRESHOLD_PCT is to make sure that the task ran
		 * at least 85% in the last window to compensate any
		 * over estimating being done.
		 */
		stats[cpu].nr = (int)div64_u64((tmp_nr + NR_THRESHOLD_PCT),
								100);
		stats[cpu].nr_misfit = (int)div64_u64((tmp_misfit +
						NR_THRESHOLD_PCT), 100);
		stats[cpu].nr_max = per_cpu(nr_max, cpu);
		stats[cpu].nr_scaled = tmp_nr;

		trace_sched_get_nr_running_avg(cpu, stats[cpu].nr,
				stats[cpu].nr_misfit, stats[cpu].nr_max,
				stats[cpu].nr_scaled);

		per_cpu(last_time, cpu) = curr_time;
		per_cpu(nr_prod_sum, cpu) = 0;
		per_cpu(nr_big_prod_sum, cpu) = 0;
		per_cpu(nr_max, cpu) = per_cpu(nr, cpu);

		spin_unlock_irqrestore(&per_cpu(nr_lock, cpu), flags);
	}

	/* collect cluster load stats */
	for_each_sched_cluster(cluster) {
		unsigned int num_cpus = cpumask_weight(&cluster->cpus);
		unsigned int sum_util_pct = 0;

		/* load is already scaled, see freq_policy_load/prev_runnable_sum */
		for_each_cpu(cpu, &cluster->cpus) {
			struct rq *rq = cpu_rq(cpu);
			struct walt_rq *wrq = (struct walt_rq *) rq->android_vendor_data1;

			/* compute the % this cpu's utilization of the cpu capacity,
			 * and sum it across all cpus
			 */
			sum_util_pct +=
				(wrq->util * 100) / arch_scale_cpu_capacity(cpu);
		}

		/* calculate the averge per-cpu utilization */
		cstats_util_pct[cluster->id] = sum_util_pct / num_cpus;
	}

	for_each_possible_cpu(cpu) {
		if (per_cpu(coloc_hyst_time, cpu)) {
			any_hyst_time = true;
			break;
		}
	}
	if (any_hyst_time && get_rtgb_active_time() >= MAX_RTGB_TIME)
		sched_update_hyst_times();

	last_get_time = curr_time;

done:
	return &stats[0];
}
EXPORT_SYMBOL(sched_get_nr_running_avg);

void sched_update_hyst_times(void)
{
	bool rtgb_active;
	int cpu;
	unsigned long cpu_cap, coloc_busy_pct;

	rtgb_active = is_rtgb_active() && (sched_boost_type != CONSERVATIVE_BOOST)
			&& (get_rtgb_active_time() < MAX_RTGB_TIME);

	for_each_possible_cpu(cpu) {
		cpu_cap = arch_scale_cpu_capacity(cpu);
		coloc_busy_pct = sysctl_sched_coloc_busy_hyst_cpu_busy_pct[cpu];
		per_cpu(hyst_time, cpu) = (BIT(cpu)
			     & sysctl_sched_busy_hyst_enable_cpus) ?
			     sysctl_sched_busy_hyst : 0;
		per_cpu(coloc_hyst_time, cpu) = ((BIT(cpu)
			     & sysctl_sched_coloc_busy_hyst_enable_cpus)
			     && rtgb_active) ?
			     sysctl_sched_coloc_busy_hyst_cpu[cpu] : 0;
		per_cpu(coloc_hyst_busy, cpu) = mult_frac(cpu_cap,
							coloc_busy_pct, 100);
		per_cpu(util_hyst_time, cpu) = (BIT(cpu)
				& sysctl_sched_util_busy_hyst_enable_cpus) ?
				sysctl_sched_util_busy_hyst_cpu[cpu] : 0;
	}
}

#define BUSY_NR_RUN		3
#define BUSY_LOAD_FACTOR	10
static inline void update_busy_hyst_end_time(int cpu, int enq,
				unsigned long prev_nr_run, u64 curr_time)
{
	bool nr_run_trigger = false;
	bool load_trigger = false, coloc_load_trigger = false;
	u64 agg_hyst_time, total_util = 0;
	bool util_load_trigger = false;
	int i;
	bool hyst_trigger, coloc_trigger;
	bool dequeue = (enq < 0);

	if (!per_cpu(hyst_time, cpu) && !per_cpu(coloc_hyst_time, cpu) &&
	    !per_cpu(util_hyst_time, cpu))
		return;

	if (prev_nr_run >= BUSY_NR_RUN && per_cpu(nr, cpu) < BUSY_NR_RUN)
		nr_run_trigger = true;

	if (dequeue && (cpu_util(cpu) * BUSY_LOAD_FACTOR) >
			capacity_orig_of(cpu))
		load_trigger = true;

	if (dequeue && cpu_util(cpu) > per_cpu(coloc_hyst_busy, cpu))
		coloc_load_trigger = true;

	if (dequeue) {
		for_each_possible_cpu(i) {
			total_util += cpu_util(i);
			if (total_util >= sysctl_sched_util_busy_hyst_cpu_util[cpu]) {
				util_load_trigger = true;
				break;
			}
		}
	}

	coloc_trigger = nr_run_trigger || coloc_load_trigger;
#if IS_ENABLED(CONFIG_SCHED_CONSERVATIVE_BOOST_LPM_BIAS)
	hyst_trigger = nr_run_trigger || load_trigger || (sched_boost_type == CONSERVATIVE_BOOST);
#else
	hyst_trigger = nr_run_trigger || load_trigger;
#endif

	agg_hyst_time = max(max(hyst_trigger ? per_cpu(hyst_time, cpu) : 0,
			    coloc_trigger ? per_cpu(coloc_hyst_time, cpu) : 0),
			    util_load_trigger ?	per_cpu(util_hyst_time, cpu) : 0);

	if (agg_hyst_time) {
		atomic64_set(&per_cpu(busy_hyst_end_time, cpu),
				curr_time + agg_hyst_time);
		trace_sched_busy_hyst_time(cpu, agg_hyst_time, prev_nr_run,
					cpu_util(cpu), per_cpu(hyst_time, cpu),
					per_cpu(coloc_hyst_time, cpu),
					per_cpu(util_hyst_time, cpu));
	}
}

int sched_busy_hyst_handler(struct ctl_table *table, int write,
				void __user *buffer, size_t *lenp, loff_t *ppos)
{
	int ret;

	if (table->maxlen > (sizeof(unsigned int) * num_possible_cpus()))
		table->maxlen = sizeof(unsigned int) * num_possible_cpus();

	ret = proc_dointvec_minmax(table, write, buffer, lenp, ppos);

	if (!ret && write)
		sched_update_hyst_times();

	return ret;
}

/**
 * sched_update_nr_prod
 * @cpu: The core id of the nr running driver.
 * @enq: enqueue/dequeue/misfit happening on this CPU.
 * @return: N/A
 *
 * Update average with latest nr_running value for CPU
 */
void sched_update_nr_prod(int cpu, int enq)
{
	u64 diff;
	u64 curr_time;
	unsigned long flags, nr_running;

	spin_lock_irqsave(&per_cpu(nr_lock, cpu), flags);
	nr_running = per_cpu(nr, cpu);
	curr_time = sched_clock();
	diff = curr_time - per_cpu(last_time, cpu);
	BUG_ON((s64)diff < 0);
	per_cpu(last_time, cpu) = curr_time;
	per_cpu(nr, cpu) = cpu_rq(cpu)->nr_running;

	if (per_cpu(nr, cpu) > per_cpu(nr_max, cpu))
		per_cpu(nr_max, cpu) = per_cpu(nr, cpu);

	/* Don't update hyst time for misfit tasks */
	if (enq)
		update_busy_hyst_end_time(cpu, enq, nr_running, curr_time);

	per_cpu(nr_prod_sum, cpu) += nr_running * diff;
	per_cpu(nr_big_prod_sum, cpu) += walt_big_tasks(cpu) * diff;
	spin_unlock_irqrestore(&per_cpu(nr_lock, cpu), flags);
}

/*
 * Returns the CPU utilization % in the last window.
 */
unsigned int sched_get_cpu_util_pct(int cpu)
{
	struct rq *rq = cpu_rq(cpu);
	u64 util;
	unsigned long capacity, flags;
	unsigned int busy;
	struct walt_rq *wrq = (struct walt_rq *) cpu_rq(cpu)->android_vendor_data1;

	raw_spin_lock_irqsave(&rq->__lock, flags);

	capacity = capacity_orig_of(cpu);

	util = wrq->prev_runnable_sum + wrq->grp_time.prev_runnable_sum;
	util = scale_time_to_util(util);
	raw_spin_unlock_irqrestore(&rq->__lock, flags);

	util = (util >= capacity) ? capacity : util;
	busy = div64_ul((util * 100), capacity);
	return busy;
}

int sched_lpm_disallowed_time(int cpu, u64 *timeout)
{
	u64 now = sched_clock();
	u64 bias_end_time = atomic64_read(&per_cpu(busy_hyst_end_time, cpu));

	if (unlikely(is_reserved(cpu))) {
		*timeout = 10 * NSEC_PER_MSEC;
		return 0; /* shallowest c-state */
	}

	if (now < bias_end_time) {
		*timeout = bias_end_time - now;
		return 0; /* shallowest c-state */
	}

	return INT_MAX; /* don't care */
}
EXPORT_SYMBOL(sched_lpm_disallowed_time);