From 064706514ec3fea740c2656e03c4f01f6a551ac4 Mon Sep 17 00:00:00 2001 From: Mark Rutland Date: Mon, 3 Jun 2013 13:33:53 -0700 Subject: clocksource: Add generic dummy timer driver 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 Signed-off-by: Stephen Boyd Acked-by: Marc Zyngier , Cc: John Stultz Cc: Daniel Lezcano 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 --- drivers/clocksource/dummy_timer.c | 69 +++++++++++++++++++++++++++++++++++++++ 1 file changed, 69 insertions(+) create mode 100644 drivers/clocksource/dummy_timer.c (limited to 'drivers/clocksource/dummy_timer.c') diff --git a/drivers/clocksource/dummy_timer.c b/drivers/clocksource/dummy_timer.c new file mode 100644 index 000000000000..1f55f9620338 --- /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); -- cgit v1.2.3 From 8c37bb3ac95b8ff953bd3c8bc8dd0a393d5ae989 Mon Sep 17 00:00:00 2001 From: Paul Gortmaker Date: Wed, 19 Jun 2013 11:32:08 -0400 Subject: clocksource+irqchip: delete __cpuinit usage from all related files The __cpuinit type of throwaway sections might have made sense some time ago when RAM was more constrained, but now the savings do not offset the cost and complications. For example, the fix in commit 5e427ec2d0 ("x86: Fix bit corruption at CPU resume time") is a good example of the nasty type of bugs that can be created with improper use of the various __init prefixes. After a discussion on LKML[1] it was decided that cpuinit should go the way of devinit and be phased out. Once all the users are gone, we can then finally remove the macros themselves from linux/init.h. This removes all the drivers/clocksource and drivers/irqchip uses of the __cpuinit macros from all C files. [1] https://lkml.org/lkml/2013/5/20/589 Cc: John Stultz Cc: Thomas Gleixner Acked-by: Thomas Gleixner Signed-off-by: Paul Gortmaker --- drivers/clocksource/dummy_timer.c | 6 +++--- 1 file changed, 3 insertions(+), 3 deletions(-) (limited to 'drivers/clocksource/dummy_timer.c') diff --git a/drivers/clocksource/dummy_timer.c b/drivers/clocksource/dummy_timer.c index 1f55f9620338..b3eb582d6a6f 100644 --- a/drivers/clocksource/dummy_timer.c +++ b/drivers/clocksource/dummy_timer.c @@ -25,7 +25,7 @@ static void dummy_timer_set_mode(enum clock_event_mode mode, */ } -static void __cpuinit dummy_timer_setup(void) +static void dummy_timer_setup(void) { int cpu = smp_processor_id(); struct clock_event_device *evt = __this_cpu_ptr(&dummy_timer_evt); @@ -41,7 +41,7 @@ static void __cpuinit dummy_timer_setup(void) clockevents_register_device(evt); } -static int __cpuinit dummy_timer_cpu_notify(struct notifier_block *self, +static int dummy_timer_cpu_notify(struct notifier_block *self, unsigned long action, void *hcpu) { if ((action & ~CPU_TASKS_FROZEN) == CPU_STARTING) @@ -50,7 +50,7 @@ static int __cpuinit dummy_timer_cpu_notify(struct notifier_block *self, return NOTIFY_OK; } -static struct notifier_block dummy_timer_cpu_nb __cpuinitdata = { +static struct notifier_block dummy_timer_cpu_nb = { .notifier_call = dummy_timer_cpu_notify, }; -- cgit v1.2.3