dummy_timer.c
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/*
* linux/drivers/clocksource/dummy_timer.c
*
* Copyright (C) 2013 ARM Ltd.
* 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.
*/
#include <linux/clockchips.h>
#include <linux/cpu.h>
#include <linux/init.h>
#include <linux/percpu.h>
#include <linux/cpumask.h>
static DEFINE_PER_CPU(struct clock_event_device, dummy_timer_evt);
static void dummy_timer_set_mode(enum clock_event_mode mode,
struct clock_event_device *evt)
{
/*
* Core clockevents code will call this when exchanging timer devices.
* We don't need to do anything here.
*/
}
static void dummy_timer_setup(void)
{
int cpu = smp_processor_id();
struct clock_event_device *evt = __this_cpu_ptr(&dummy_timer_evt);
evt->name = "dummy_timer";
evt->features = CLOCK_EVT_FEAT_PERIODIC |
CLOCK_EVT_FEAT_ONESHOT |
CLOCK_EVT_FEAT_DUMMY;
evt->rating = 100;
evt->set_mode = dummy_timer_set_mode;
evt->cpumask = cpumask_of(cpu);
clockevents_register_device(evt);
}
static int dummy_timer_cpu_notify(struct notifier_block *self,
unsigned long action, void *hcpu)
{
if ((action & ~CPU_TASKS_FROZEN) == CPU_STARTING)
dummy_timer_setup();
return NOTIFY_OK;
}
static struct notifier_block dummy_timer_cpu_nb = {
.notifier_call = dummy_timer_cpu_notify,
};
static int __init dummy_timer_register(void)
{
int err = register_cpu_notifier(&dummy_timer_cpu_nb);
if (err)
return err;
/* We won't get a call on the boot CPU, so register immediately */
if (num_possible_cpus() > 1)
dummy_timer_setup();
return 0;
}
early_initcall(dummy_timer_register);