From mboxrd@z Thu Jan 1 00:00:00 1970 From: virtuoso@slind.org (Alexander Shishkin) Date: Thu, 18 Mar 2010 15:33:41 +0200 Subject: [PATCH 1/1] [RFC] arm: add half-word __xchg In-Reply-To: <20100318123223.GA6855@Krystal> References: <20100318123223.GA6855@Krystal> Message-ID: <1268919221-2748-1-git-send-email-virtuoso@slind.org> To: linux-arm-kernel@lists.infradead.org List-Id: linux-arm-kernel.lists.infradead.org On systems where ldrexh/strexh are not available, use a generic local version or __bad_xchg() on SMP. Signed-off-by: Alexander Shishkin CC: linux-arm-kernel-bounces at lists.infradead.org CC: Imre Deak CC: Mathieu Desnoyers --- arch/arm/include/asm/system.h | 65 ++++++++++++++++++++++++++++++++++------ 1 files changed, 55 insertions(+), 10 deletions(-) diff --git a/arch/arm/include/asm/system.h b/arch/arm/include/asm/system.h index d65b2f5..82248ae 100644 --- a/arch/arm/include/asm/system.h +++ b/arch/arm/include/asm/system.h @@ -218,6 +218,39 @@ do { \ last = __switch_to(prev,task_thread_info(prev), task_thread_info(next)); \ } while (0) +static inline unsigned long __xchg_local_generic(unsigned long x, + volatile void *ptr, int size) +{ + extern void __bad_xchg(volatile void *, int); + unsigned long ret; + unsigned long flags; + + switch (size) { + case 1: + raw_local_irq_save(flags); + ret = *(volatile unsigned char *)ptr; + *(volatile unsigned char *)ptr = x; + raw_local_irq_restore(flags); + break; + + case 2: + raw_local_irq_save(flags); + ret = *(volatile unsigned short *)ptr; + *(volatile unsigned short *)ptr = x; + raw_local_irq_restore(flags); + break; + + case 4: + raw_local_irq_save(flags); + ret = *(volatile unsigned long *)ptr; + *(volatile unsigned long *)ptr = x; + raw_local_irq_restore(flags); + break; + } + + return ret; +} + #if defined(CONFIG_CPU_SA1100) || defined(CONFIG_CPU_SA110) /* * On the StrongARM, "swp" is terminally broken since it bypasses the @@ -262,6 +295,26 @@ static inline unsigned long __xchg(unsigned long x, volatile void *ptr, int size : "r" (x), "r" (ptr) : "memory", "cc"); break; +#ifdef CONFIG_CPU_32v6K + case 2: + asm volatile("@ __xchg2\n" + "1: ldrexh %0, [%3]\n" + " strexh %1, %2, [%3]\n" + " teq %1, #0\n" + " bne 1b" + : "=&r" (ret), "=&r" (tmp) + : "r" (x), "r" (ptr) + : "memory", "cc"); + break; +#else + case 2: +#ifdef CONFIG_SMP + __bad_xchg(ptr, size), ret = 0; +#else + ret = __xchg_local_generic(x, ptr, 2); +#endif + break; +#endif case 4: asm volatile("@ __xchg4\n" "1: ldrex %0, [%3]\n" @@ -277,17 +330,9 @@ static inline unsigned long __xchg(unsigned long x, volatile void *ptr, int size #error SMP is not supported on this platform #endif case 1: - raw_local_irq_save(flags); - ret = *(volatile unsigned char *)ptr; - *(volatile unsigned char *)ptr = x; - raw_local_irq_restore(flags); - break; - + case 2: case 4: - raw_local_irq_save(flags); - ret = *(volatile unsigned long *)ptr; - *(volatile unsigned long *)ptr = x; - raw_local_irq_restore(flags); + ret = __xchg_local_generic(x, ptr, size); break; #else case 1: -- 1.6.3.3