/**
   * @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.
  ");
  	return 0;
  }