From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752039Ab3FFQXm (ORCPT ); Thu, 6 Jun 2013 12:23:42 -0400 Received: from mail-ea0-f173.google.com ([209.85.215.173]:56839 "EHLO mail-ea0-f173.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751207Ab3FFQXk (ORCPT ); Thu, 6 Jun 2013 12:23:40 -0400 Message-ID: <51B0B785.5080707@linaro.org> Date: Thu, 06 Jun 2013 18:23:33 +0200 From: Daniel Lezcano User-Agent: Mozilla/5.0 (X11; Linux i686; rv:17.0) Gecko/20130510 Thunderbird/17.0.6 MIME-Version: 1.0 To: Stephen Boyd CC: linux-arm-kernel@lists.infradead.org, Mark Rutland , linux-kernel@vger.kernel.org, linux-arm-msm@vger.kernel.org, John Stultz , Thomas Gleixner Subject: Re: [PATCHv7 02/11] clocksource: add generic dummy timer driver References: <1370291642-13259-1-git-send-email-sboyd@codeaurora.org> <1370291642-13259-3-git-send-email-sboyd@codeaurora.org> In-Reply-To: <1370291642-13259-3-git-send-email-sboyd@codeaurora.org> Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 06/03/2013 10:33 PM, Stephen Boyd wrote: > From: Mark Rutland > > 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. > > Signed-off-by: Mark Rutland > Acked-by: Marc Zyngier , > Cc: John Stultz > Cc: Thomas Gleixner > Cc: Daniel Lezcano > [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: Stephen Boyd > --- Except the missing first letter capitalization, in the patch description 'add' => 'Add'. Acked-by: Daniel Lezcano > drivers/clocksource/Makefile | 1 + > drivers/clocksource/dummy_timer.c | 69 +++++++++++++++++++++++++++++++++++++++ > 2 files changed, 70 insertions(+) > create mode 100644 drivers/clocksource/dummy_timer.c > > diff --git a/drivers/clocksource/Makefile b/drivers/clocksource/Makefile > index 8d979c7..1a17d76 100644 > --- a/drivers/clocksource/Makefile > +++ b/drivers/clocksource/Makefile > @@ -29,3 +29,4 @@ obj-$(CONFIG_CLKSRC_SAMSUNG_PWM) += samsung_pwm_timer.o > > obj-$(CONFIG_ARM_ARCH_TIMER) += arm_arch_timer.o > obj-$(CONFIG_CLKSRC_METAG_GENERIC) += metag_generic.o > +obj-$(CONFIG_ARCH_HAS_TICK_BROADCAST) += dummy_timer.o > diff --git a/drivers/clocksource/dummy_timer.c b/drivers/clocksource/dummy_timer.c > new file mode 100644 > index 0000000..1f55f96 > --- /dev/null > +++ b/drivers/clocksource/dummy_timer.c > @@ -0,0 +1,69 @@ > +/* > + * 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 > +#include > +#include > +#include > +#include > + > +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); > -- Linaro.org │ Open source software for ARM SoCs Follow Linaro: Facebook | Twitter | Blog