[go: nahoru, domu]
1/*
2 *  linux/drivers/clocksource/dummy_timer.c
3 *
4 *  Copyright (C) 2013 ARM Ltd.
5 *  All Rights Reserved
6 *
7 * This program is free software; you can redistribute it and/or modify
8 * it under the terms of the GNU General Public License version 2 as
9 * published by the Free Software Foundation.
10 */
11#include <linux/clockchips.h>
12#include <linux/cpu.h>
13#include <linux/init.h>
14#include <linux/percpu.h>
15#include <linux/cpumask.h>
16
17static DEFINE_PER_CPU(struct clock_event_device, dummy_timer_evt);
18
19static void dummy_timer_set_mode(enum clock_event_mode mode,
20			   struct clock_event_device *evt)
21{
22	/*
23	 * Core clockevents code will call this when exchanging timer devices.
24	 * We don't need to do anything here.
25	 */
26}
27
28static void dummy_timer_setup(void)
29{
30	int cpu = smp_processor_id();
31	struct clock_event_device *evt = raw_cpu_ptr(&dummy_timer_evt);
32
33	evt->name	= "dummy_timer";
34	evt->features	= CLOCK_EVT_FEAT_PERIODIC |
35			  CLOCK_EVT_FEAT_ONESHOT |
36			  CLOCK_EVT_FEAT_DUMMY;
37	evt->rating	= 100;
38	evt->set_mode	= dummy_timer_set_mode;
39	evt->cpumask	= cpumask_of(cpu);
40
41	clockevents_register_device(evt);
42}
43
44static int dummy_timer_cpu_notify(struct notifier_block *self,
45				      unsigned long action, void *hcpu)
46{
47	if ((action & ~CPU_TASKS_FROZEN) == CPU_STARTING)
48		dummy_timer_setup();
49
50	return NOTIFY_OK;
51}
52
53static struct notifier_block dummy_timer_cpu_nb = {
54	.notifier_call = dummy_timer_cpu_notify,
55};
56
57static int __init dummy_timer_register(void)
58{
59	int err = 0;
60
61	cpu_notifier_register_begin();
62	err = __register_cpu_notifier(&dummy_timer_cpu_nb);
63	if (err)
64		goto out;
65
66	/* We won't get a call on the boot CPU, so register immediately */
67	if (num_possible_cpus() > 1)
68		dummy_timer_setup();
69
70out:
71	cpu_notifier_register_done();
72	return err;
73}
74early_initcall(dummy_timer_register);
75