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ARM: 6428/1: add cpu_idle_wait() to support CPUidle on SMP systems. 

In order for CPUidle to work on SMP systems, an implementation of
cpu_idle_wait() is needed.

This patch duplicates the x86 implementation of cpu_idle_wait() for
ARM.

Tested-by: Colin Cross <ccross@android.com>
Signed-off-by: Kevin Hilman <khilman@deeprootsystems.com>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
This commit is contained in:
Kevin Hilman 2010-10-01 22:13:47 +01:00 committed by Russell King
parent 7511db9d25
commit c7b0aff44a
3 changed files with 24 additions and 0 deletions
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3
arch/arm/Kconfig
View File

@ -145,6 +145,9 @@ config ARCH_HAS_CPUFREQ
and that the relevant menu configurations are displayed for
it.
config ARCH_HAS_CPU_IDLE_WAIT
def_bool y
config GENERIC_HWEIGHT
bool
default y

2
arch/arm/include/asm/system.h
View File

@ -325,6 +325,8 @@ static inline unsigned long __xchg(unsigned long x, volatile void *ptr, int size
extern void disable_hlt(void);
extern void enable_hlt(void);
void cpu_idle_wait(void);
#include <asm-generic/cmpxchg-local.h>
#if __LINUX_ARM_ARCH__ < 6

19
arch/arm/kernel/process.c
View File

@ -135,6 +135,25 @@ EXPORT_SYMBOL(pm_power_off);
void (*arm_pm_restart)(char str, const char *cmd) = arm_machine_restart;
EXPORT_SYMBOL_GPL(arm_pm_restart);
static void do_nothing(void *unused)
{
}
/*
* cpu_idle_wait - Used to ensure that all the CPUs discard old value of
* pm_idle and update to new pm_idle value. Required while changing pm_idle
* handler on SMP systems.
*
* Caller must have changed pm_idle to the new value before the call. Old
* pm_idle value will not be used by any CPU after the return of this function.
*/
void cpu_idle_wait(void)
{
smp_mb();
/* kick all the CPUs so that they exit out of pm_idle */
smp_call_function(do_nothing, NULL, 1);
}
EXPORT_SYMBOL_GPL(cpu_idle_wait);
/*
* This is our default idle handler. We need to disable