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| author | Kevin Hilman <khilman@deeprootsystems.com> | 2010-10-01 22:13:47 +0100 |
|---|---|---|
| committer | Russell King <rmk+kernel@arm.linux.org.uk> | 2010-10-08 10:02:24 +0100 |
| commit | c7b0aff44a0740eedd31b759fd08d9e25672fa76 (patch) | |
| tree | 02991fc91b0733c6b0f2ce8de2d0741b5ff43ef6 | |
| parent | 7511db9d25080d53e5427bf4b8849278c07019bc (diff) | |
| download | lwn-c7b0aff44a0740eedd31b759fd08d9e25672fa76.tar.gz lwn-c7b0aff44a0740eedd31b759fd08d9e25672fa76.zip | |
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>
| -rw-r--r-- | arch/arm/Kconfig | 3 | ||||
| -rw-r--r-- | arch/arm/include/asm/system.h | 2 | ||||
| -rw-r--r-- | arch/arm/kernel/process.c | 19 |
3 files changed, 24 insertions, 0 deletions
diff --git a/arch/arm/Kconfig b/arch/arm/Kconfig index 7562f884f2c5..94360e7a7abc 100644 --- a/arch/arm/Kconfig +++ b/arch/arm/Kconfig @@ -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 diff --git a/arch/arm/include/asm/system.h b/arch/arm/include/asm/system.h index 8ba1ccf82a02..48e360c74327 100644 --- a/arch/arm/include/asm/system.h +++ b/arch/arm/include/asm/system.h @@ -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 diff --git a/arch/arm/kernel/process.c b/arch/arm/kernel/process.c index 401e38be1f78..23def52d2d24 100644 --- a/arch/arm/kernel/process.c +++ b/arch/arm/kernel/process.c @@ -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 |