/**
 * @file timer_int.c
 *
 * @remark Copyright 2002 OProfile authors
 * @remark Read the file COPYING
 *
 * @author John Levon <levon@movementarian.org>
 */

#include <linux/kernel.h>
#include <linux/notifier.h>
#include <linux/smp.h>
#include <linux/oprofile.h>
#include <linux/profile.h>
#include <linux/init.h>
#include <linux/cpu.h>
#include <linux/hrtimer.h>
#include <asm/irq_regs.h>
#include <asm/ptrace.h>

#include "oprof.h"

static DEFINE_PER_CPU(struct hrtimer, oprofile_hrtimer);
static int ctr_running;

static enum hrtimer_restart oprofile_hrtimer_notify(struct hrtimer *hrtimer)
{
	oprofile_add_sample(get_irq_regs(), 0);
	hrtimer_forward_now(hrtimer, ns_to_ktime(TICK_NSEC));
	return HRTIMER_RESTART;
}

static void __oprofile_hrtimer_start(void *unused)
{
	struct hrtimer *hrtimer = this_cpu_ptr(&oprofile_hrtimer);

	if (!ctr_running)
		return;

	hrtimer_init(hrtimer, CLOCK_MONOTONIC, HRTIMER_MODE_REL);
	hrtimer->function = oprofile_hrtimer_notify;

	hrtimer_start(hrtimer, ns_to_ktime(TICK_NSEC),
		      HRTIMER_MODE_REL_PINNED);
}

static int oprofile_hrtimer_start(void)
{
	get_online_cpus();
	ctr_running = 1;
	on_each_cpu(__oprofile_hrtimer_start, NULL, 1);
	put_online_cpus();
	return 0;
}

static void __oprofile_hrtimer_stop(int cpu)
{
	struct hrtimer *hrtimer = &per_cpu(oprofile_hrtimer, cpu);

	if (!ctr_running)
		return;

	hrtimer_cancel(hrtimer);
}

static void oprofile_hrtimer_stop(void)
{
	int cpu;

	get_online_cpus();
	for_each_online_cpu(cpu)
		__oprofile_hrtimer_stop(cpu);
	ctr_running = 0;
	put_online_cpus();
}

static int oprofile_timer_online(unsigned int cpu)
{
	local_irq_disable();
	__oprofile_hrtimer_start(NULL);
	local_irq_enable();
	return 0;
}

static int oprofile_timer_prep_down(unsigned int cpu)
{
	__oprofile_hrtimer_stop(cpu);
	return 0;
}

static enum cpuhp_state hp_online;

static int oprofile_hrtimer_setup(void)
{
	int ret;

	ret = cpuhp_setup_state_nocalls(CPUHP_AP_ONLINE_DYN,
					"oprofile/timer:online",
					oprofile_timer_online,
					oprofile_timer_prep_down);
	if (ret < 0)
		return ret;
	hp_online = ret;
	return 0;
}

static void oprofile_hrtimer_shutdown(void)
{
	cpuhp_remove_state_nocalls(hp_online);
}

int oprofile_timer_init(struct oprofile_operations *ops)
{
	ops->create_files	= NULL;
	ops->setup		= oprofile_hrtimer_setup;
	ops->shutdown		= oprofile_hrtimer_shutdown;
	ops->start		= oprofile_hrtimer_start;
	ops->stop		= oprofile_hrtimer_stop;
	ops->cpu_type		= "timer";
	printk(KERN_INFO "oprofile: using timer interrupt.\n");
	return 0;
}