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 17 static DEFINE_PER_CPU(struct clock_event_device, dummy_timer_evt); 18 19 static void dummy_timer_setup(void) 20 { 21 int cpu = smp_processor_id(); 22 struct clock_event_device *evt = raw_cpu_ptr(&dummy_timer_evt); 23 24 evt->name = "dummy_timer"; 25 evt->features = CLOCK_EVT_FEAT_PERIODIC | 26 CLOCK_EVT_FEAT_ONESHOT | 27 CLOCK_EVT_FEAT_DUMMY; 28 evt->rating = 100; 29 evt->cpumask = cpumask_of(cpu); 30 31 clockevents_register_device(evt); 32 } 33 34 static int dummy_timer_cpu_notify(struct notifier_block *self, 35 unsigned long action, void *hcpu) 36 { 37 if ((action & ~CPU_TASKS_FROZEN) == CPU_STARTING) 38 dummy_timer_setup(); 39 40 return NOTIFY_OK; 41 } 42 43 static struct notifier_block dummy_timer_cpu_nb = { 44 .notifier_call = dummy_timer_cpu_notify, 45 }; 46 47 static int __init dummy_timer_register(void) 48 { 49 int err = 0; 50 51 cpu_notifier_register_begin(); 52 err = __register_cpu_notifier(&dummy_timer_cpu_nb); 53 if (err) 54 goto out; 55 56 /* We won't get a call on the boot CPU, so register immediately */ 57 if (num_possible_cpus() > 1) 58 dummy_timer_setup(); 59 60 out: 61 cpu_notifier_register_done(); 62 return err; 63 } 64 early_initcall(dummy_timer_register); 65