From mboxrd@z Thu Jan 1 00:00:00 1970 From: Kevin Hilman Subject: [PATCH] ARM: add cpu_idle_wait() to support CPUidle on SMP systems. Date: Tue, 28 Sep 2010 09:43:12 -0700 Message-ID: <1285692192-32075-1-git-send-email-khilman@deeprootsystems.com> Return-path: Received: from mail-pw0-f46.google.com ([209.85.160.46]:47667 "EHLO mail-pw0-f46.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752955Ab0I1QnQ (ORCPT ); Tue, 28 Sep 2010 12:43:16 -0400 Received: by pwi1 with SMTP id 1so360316pwi.19 for ; Tue, 28 Sep 2010 09:43:15 -0700 (PDT) Sender: linux-omap-owner@vger.kernel.org List-Id: linux-omap@vger.kernel.org To: linux-arm-kernel@lists.infradead.org Cc: linux-omap@vger.kernel.org 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. Signed-off-by: Kevin Hilman --- arch/arm/Kconfig | 3 +++ arch/arm/include/asm/system.h | 2 ++ arch/arm/kernel/process.c | 19 +++++++++++++++++++ 3 files changed, 24 insertions(+), 0 deletions(-) diff --git a/arch/arm/Kconfig b/arch/arm/Kconfig index 553b7cf..10ce6dc 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 8ba1ccf..48e360c 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 #if __LINUX_ARM_ARCH__ < 6 diff --git a/arch/arm/kernel/process.c b/arch/arm/kernel/process.c index 401e38b..23def52 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 -- 1.7.2.1