1/**
  2 * @file timer_int.c
  3 *
  4 * @remark Copyright 2002 OProfile authors
  5 * @remark Read the file COPYING
  6 *
  7 * @author John Levon <levon@movementarian.org>
  8 */
  9
 10#include <linux/kernel.h>
 11#include <linux/notifier.h>
 12#include <linux/smp.h>
 13#include <linux/oprofile.h>
 14#include <linux/profile.h>
 15#include <linux/init.h>
 16#include <linux/cpu.h>
 17#include <linux/hrtimer.h>
 18#include <asm/irq_regs.h>
 19#include <asm/ptrace.h>
 20
 21#include "oprof.h"
 22
 23static DEFINE_PER_CPU(struct hrtimer, oprofile_hrtimer);
 24static int ctr_running;
 25
 26static enum hrtimer_restart oprofile_hrtimer_notify(struct hrtimer *hrtimer)
 27{
 28	oprofile_add_sample(get_irq_regs(), 0);
 29	hrtimer_forward_now(hrtimer, ns_to_ktime(TICK_NSEC));
 30	return HRTIMER_RESTART;
 31}
 32
 33static void __oprofile_hrtimer_start(void *unused)
 34{
 35	struct hrtimer *hrtimer = this_cpu_ptr(&oprofile_hrtimer);
 36
 37	if (!ctr_running)
 38		return;
 39
 40	hrtimer_init(hrtimer, CLOCK_MONOTONIC, HRTIMER_MODE_REL);
 41	hrtimer->function = oprofile_hrtimer_notify;
 42
 43	hrtimer_start(hrtimer, ns_to_ktime(TICK_NSEC),
 44		      HRTIMER_MODE_REL_PINNED);
 45}
 46
 47static int oprofile_hrtimer_start(void)
 48{
 49	get_online_cpus();
 50	ctr_running = 1;
 51	on_each_cpu(__oprofile_hrtimer_start, NULL, 1);
 52	put_online_cpus();
 53	return 0;
 54}
 55
 56static void __oprofile_hrtimer_stop(int cpu)
 57{
 58	struct hrtimer *hrtimer = &per_cpu(oprofile_hrtimer, cpu);
 59
 60	if (!ctr_running)
 61		return;
 62
 63	hrtimer_cancel(hrtimer);
 64}
 65
 66static void oprofile_hrtimer_stop(void)
 67{
 68	int cpu;
 69
 70	get_online_cpus();
 71	for_each_online_cpu(cpu)
 72		__oprofile_hrtimer_stop(cpu);
 73	ctr_running = 0;
 74	put_online_cpus();
 75}
 76
 77static int oprofile_timer_online(unsigned int cpu)
 78{
 79	local_irq_disable();
 80	__oprofile_hrtimer_start(NULL);
 81	local_irq_enable();
 82	return 0;
 83}
 84
 85static int oprofile_timer_prep_down(unsigned int cpu)
 86{
 87	__oprofile_hrtimer_stop(cpu);
 88	return 0;
 89}
 90
 91static enum cpuhp_state hp_online;
 92
 93static int oprofile_hrtimer_setup(void)
 94{
 95	int ret;
 96
 97	ret = cpuhp_setup_state_nocalls(CPUHP_AP_ONLINE_DYN,
 98					"oprofile/timer:online",
 99					oprofile_timer_online,
100					oprofile_timer_prep_down);
101	if (ret < 0)
102		return ret;
103	hp_online = ret;
104	return 0;
105}
106
107static void oprofile_hrtimer_shutdown(void)
108{
109	cpuhp_remove_state_nocalls(hp_online);
110}
111
112int oprofile_timer_init(struct oprofile_operations *ops)
113{
114	ops->create_files	= NULL;
115	ops->setup		= oprofile_hrtimer_setup;
116	ops->shutdown		= oprofile_hrtimer_shutdown;
117	ops->start		= oprofile_hrtimer_start;
118	ops->stop		= oprofile_hrtimer_stop;
119	ops->cpu_type		= "timer";
120	printk(KERN_INFO "oprofile: using timer interrupt.\n");
121	return 0;
122}