[RFC PATCH 16/16] ARM: local timers: remove local timer support from arch/arm
Marc Zyngier
marc.zyngier at arm.com
Thu Jun 16 15:06:44 EDT 2011
Local timer support in arch/arm is now completely unused, as all
in-tree platforms are using LOCAL_TIMER_DEVICES.
It allows us to simplify the code, only preserving the broadcast timer.
Signed-off-by: Marc Zyngier <marc.zyngier at arm.com>
---
arch/arm/Kconfig | 10 -----
arch/arm/include/asm/localtimer.h | 48 -------------------------
arch/arm/kernel/smp.c | 70 +++++++-----------------------------
3 files changed, 14 insertions(+), 114 deletions(-)
delete mode 100644 arch/arm/include/asm/localtimer.h
diff --git a/arch/arm/Kconfig b/arch/arm/Kconfig
index f3c1124..3f4eecd 100644
--- a/arch/arm/Kconfig
+++ b/arch/arm/Kconfig
@@ -1406,16 +1406,6 @@ config HOTPLUG_CPU
Say Y here to experiment with turning CPUs off and on. CPUs
can be controlled through /sys/devices/system/cpu.
-config LOCAL_TIMERS
- bool "Use local timer interrupts"
- depends on SMP && !LOCAL_TIMER_DEVICES
- default y
- help
- Enable support for local timers on SMP platforms, rather then the
- legacy IPI broadcast method. Local timers allows the system
- accounting to be spread across the timer interval, preventing a
- "thundering herd" at every timer tick.
-
config LOCAL_TIMER_DEVICES
bool
diff --git a/arch/arm/include/asm/localtimer.h b/arch/arm/include/asm/localtimer.h
deleted file mode 100644
index 74af2cd..0000000
--- a/arch/arm/include/asm/localtimer.h
+++ /dev/null
@@ -1,48 +0,0 @@
-/*
- * arch/arm/include/asm/localtimer.h
- *
- * Copyright (C) 2004-2005 ARM Ltd.
- *
- * 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.
- */
-#ifndef __ASM_ARM_LOCALTIMER_H
-#define __ASM_ARM_LOCALTIMER_H
-
-#include <linux/interrupt.h>
-
-struct clock_event_device;
-
-/*
- * Setup a per-cpu timer, whether it be a local timer or dummy broadcast
- */
-void percpu_timer_setup(void);
-
-/*
- * Per-cpu timer IRQ handler
- */
-irqreturn_t percpu_timer_handler(int irq, void *dev_id);
-
-#ifdef CONFIG_LOCAL_TIMERS
-
-/*
- * Platform provides this to acknowledge a local timer IRQ.
- * Returns true if the local timer IRQ is to be processed.
- */
-int local_timer_ack(void);
-
-/*
- * Setup a local timer interrupt for a CPU.
- */
-int local_timer_setup(struct clock_event_device *);
-
-#else
-
-static inline int local_timer_setup(struct clock_event_device *evt)
-{
- return -ENXIO;
-}
-#endif
-
-#endif
diff --git a/arch/arm/kernel/smp.c b/arch/arm/kernel/smp.c
index 35135b0..214dee3 100644
--- a/arch/arm/kernel/smp.c
+++ b/arch/arm/kernel/smp.c
@@ -38,7 +38,6 @@
#include <asm/sections.h>
#include <asm/tlbflush.h>
#include <asm/ptrace.h>
-#include <asm/localtimer.h>
/*
* as from 2.5, kernels no longer have an init_tasks structure
@@ -154,8 +153,6 @@ int __cpuinit __cpu_up(unsigned int cpu)
}
#ifdef CONFIG_HOTPLUG_CPU
-static void percpu_timer_stop(void);
-
/*
* __cpu_disable runs on the processor to be shutdown.
*/
@@ -181,11 +178,6 @@ int __cpu_disable(void)
migrate_irqs();
/*
- * Stop the local timer for this CPU.
- */
- percpu_timer_stop();
-
- /*
* Flush user cache and TLB mappings, and then remove this CPU
* from the vm mask set of all processes.
*/
@@ -270,6 +262,8 @@ static void __cpuinit smp_store_cpu_info(unsigned int cpuid)
cpu_info->loops_per_jiffy = loops_per_jiffy;
}
+static void broadcast_timer_setup(void);
+
/*
* This is the secondary CPU boot entry. We're using this CPUs
* idle thread stack, but a set of temporary page tables.
@@ -309,9 +303,9 @@ asmlinkage void __cpuinit secondary_start_kernel(void)
local_fiq_enable();
/*
- * Setup the percpu timer for this CPU.
+ * Setup the broadcast timer for this CPU.
*/
- percpu_timer_setup();
+ broadcast_timer_setup();
calibrate_delay();
@@ -364,10 +358,10 @@ void __init smp_prepare_cpus(unsigned int max_cpus)
if (max_cpus > 1) {
/*
- * Enable the local timer or broadcast device for the
- * boot CPU, but only if we have more than one CPU.
+ * Enable the broadcast device for the boot CPU, but
+ * only if we have more than one CPU.
*/
- percpu_timer_setup();
+ broadcast_timer_setup();
/*
* Initialise the SCU if there are more than one CPU
@@ -430,7 +424,7 @@ u64 smp_irq_stat_cpu(unsigned int cpu)
}
/*
- * Timer (local or broadcast) support
+ * Broadcast timer support
*/
static DEFINE_PER_CPU(struct clock_event_device, percpu_clockevent);
@@ -442,20 +436,6 @@ static void ipi_timer(void)
irq_exit();
}
-#ifdef CONFIG_LOCAL_TIMERS
-irqreturn_t percpu_timer_handler(int irq, void *dev_id)
-{
- struct clock_event_device *evt = dev_id;
-
- if (local_timer_ack()) {
- evt->event_handler(evt);
- return IRQ_HANDLED;
- }
-
- return IRQ_NONE;
-}
-#endif
-
#ifdef CONFIG_GENERIC_CLOCKEVENTS_BROADCAST
static void smp_timer_broadcast(const struct cpumask *mask)
{
@@ -470,8 +450,11 @@ static void broadcast_timer_set_mode(enum clock_event_mode mode,
{
}
-static void __cpuinit broadcast_timer_setup(struct clock_event_device *evt)
+static void __cpuinit broadcast_timer_setup(void)
{
+ unsigned int cpu = smp_processor_id();
+ struct clock_event_device *evt = &per_cpu(percpu_clockevent, cpu);
+
evt->name = "dummy_timer";
evt->features = CLOCK_EVT_FEAT_ONESHOT |
CLOCK_EVT_FEAT_PERIODIC |
@@ -479,37 +462,12 @@ static void __cpuinit broadcast_timer_setup(struct clock_event_device *evt)
evt->rating = 400;
evt->mult = 1;
evt->set_mode = broadcast_timer_set_mode;
+ evt->cpumask = cpumask_of(cpu);
+ evt->broadcast = smp_timer_broadcast;
clockevents_register_device(evt);
}
-void __cpuinit percpu_timer_setup(void)
-{
- unsigned int cpu = smp_processor_id();
- struct clock_event_device *evt = &per_cpu(percpu_clockevent, cpu);
-
- evt->cpumask = cpumask_of(cpu);
- evt->broadcast = smp_timer_broadcast;
-
- if (local_timer_setup(evt))
- broadcast_timer_setup(evt);
-}
-
-#ifdef CONFIG_HOTPLUG_CPU
-/*
- * The generic clock events code purposely does not stop the local timer
- * on CPU_DEAD/CPU_DEAD_FROZEN hotplug events, so we have to do it
- * manually here.
- */
-static void percpu_timer_stop(void)
-{
- unsigned int cpu = smp_processor_id();
- struct clock_event_device *evt = &per_cpu(percpu_clockevent, cpu);
-
- evt->set_mode(CLOCK_EVT_MODE_UNUSED, evt);
-}
-#endif
-
static DEFINE_SPINLOCK(stop_lock);
/*
--
1.7.0.4
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