/**
 * Copyright (C) ARM Limited 2011-2014. All rights reserved.
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License version 2 as
 * published by the Free Software Foundation.
 *
 */

void (*callback)(void);
DEFINE_PER_CPU(struct hrtimer, percpu_hrtimer);
DEFINE_PER_CPU(ktime_t, hrtimer_expire);
DEFINE_PER_CPU(int, hrtimer_is_active);
static ktime_t profiling_interval;
static void gator_hrtimer_online(void);
static void gator_hrtimer_offline(void);

static enum hrtimer_restart gator_hrtimer_notify(struct hrtimer *hrtimer)
{
	int cpu = get_logical_cpu();
	hrtimer_forward(hrtimer, per_cpu(hrtimer_expire, cpu), profiling_interval);
	per_cpu(hrtimer_expire, cpu) = ktime_add(per_cpu(hrtimer_expire, cpu), profiling_interval);
	(*callback)();
	return HRTIMER_RESTART;
}

static void gator_hrtimer_online(void)
{
	int cpu = get_logical_cpu();
	struct hrtimer *hrtimer = &per_cpu(percpu_hrtimer, cpu);

	if (per_cpu(hrtimer_is_active, cpu) || profiling_interval.tv64 == 0)
		return;

	per_cpu(hrtimer_is_active, cpu) = 1;
	hrtimer_init(hrtimer, CLOCK_MONOTONIC, HRTIMER_MODE_ABS);
	hrtimer->function = gator_hrtimer_notify;
#ifdef CONFIG_PREEMPT_RT_BASE
	hrtimer->irqsafe = 1;
#endif
	per_cpu(hrtimer_expire, cpu) = ktime_add(hrtimer->base->get_time(), profiling_interval);
	hrtimer_start(hrtimer, per_cpu(hrtimer_expire, cpu), HRTIMER_MODE_ABS_PINNED);
}

static void gator_hrtimer_offline(void)
{
	int cpu = get_logical_cpu();
	struct hrtimer *hrtimer = &per_cpu(percpu_hrtimer, cpu);

	if (!per_cpu(hrtimer_is_active, cpu))
		return;

	per_cpu(hrtimer_is_active, cpu) = 0;
	hrtimer_cancel(hrtimer);
}

static int gator_hrtimer_init(int interval, void (*func)(void))
{
	int cpu;

	(callback) = (func);

	for_each_present_cpu(cpu) {
		per_cpu(hrtimer_is_active, cpu) = 0;
	}

	// calculate profiling interval
	if (interval > 0) {
		profiling_interval = ns_to_ktime(1000000000UL / interval);
	} else {
		profiling_interval.tv64 = 0;
	}

	return 0;
}

static void gator_hrtimer_shutdown(void)
{
	/* empty */
}