mirror of
https://github.com/AuxXxilium/linux_dsm_epyc7002.git
synced 2024-12-14 17:16:41 +07:00
064706514e
Several architectures have a dummy timer driver tightly coupled with
their broadcast code to support machines without cpu-local timers (or
where there is a lack of driver support).
Since 12ad100046: "clockevents: Add generic timer broadcast function"
it's been possible to write broadcast-capable timer drivers decoupled
from the broadcast mechanism. We can use this functionality to implement
a generic dummy timer driver that can be shared by all architectures
with generic tick broadcast (ARCH_HAS_TICK_BROADCAST).
This patch implements a generic dummy timer using this facility.
[sboyd: Make percpu data static, use __this_cpu_ptr(), move to
early_initcall to properly register on each CPU, only
register if more than one CPU possible]
Signed-off-by: Mark Rutland <mark.rutland@arm.com>
Signed-off-by: Stephen Boyd <sboyd@codeaurora.org>
Acked-by: Marc Zyngier <marc.zyngier@arm.com>,
Cc: John Stultz <john.stultz@linaro.org>
Cc: Daniel Lezcano <daniel.lezcano@linaro.org>
Cc: linux-arm-kernel@lists.infradead.org
Link: http://lkml.kernel.org/r/1370291642-13259-3-git-send-email-sboyd@codeaurora.org
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
70 lines
1.7 KiB
C
70 lines
1.7 KiB
C
/*
|
|
* 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 __cpuinit 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 __cpuinit 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 __cpuinitdata = {
|
|
.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);
|