diff options
Diffstat (limited to 'arch/arm')
| -rw-r--r-- | arch/arm/include/asm/system.h | 173 |
1 files changed, 173 insertions, 0 deletions
diff --git a/arch/arm/include/asm/system.h b/arch/arm/include/asm/system.h index 7fce8f3b391d..d65b2f5bf41f 100644 --- a/arch/arm/include/asm/system.h +++ b/arch/arm/include/asm/system.h @@ -319,6 +319,12 @@ extern void enable_hlt(void); #include <asm-generic/cmpxchg-local.h> +#if __LINUX_ARM_ARCH__ < 6 + +#ifdef CONFIG_SMP +#error "SMP is not supported on this platform" +#endif + /* * cmpxchg_local and cmpxchg64_local are atomic wrt current CPU. Always make * them available. @@ -332,6 +338,173 @@ extern void enable_hlt(void); #include <asm-generic/cmpxchg.h> #endif +#else /* __LINUX_ARM_ARCH__ >= 6 */ + +extern void __bad_cmpxchg(volatile void *ptr, int size); + +/* + * cmpxchg only support 32-bits operands on ARMv6. + */ + +static inline unsigned long __cmpxchg(volatile void *ptr, unsigned long old, + unsigned long new, int size) +{ + unsigned long oldval, res; + + switch (size) { +#ifdef CONFIG_CPU_32v6K + case 1: + do { + asm volatile("@ __cmpxchg1\n" + " ldrexb %1, [%2]\n" + " mov %0, #0\n" + " teq %1, %3\n" + " strexbeq %0, %4, [%2]\n" + : "=&r" (res), "=&r" (oldval) + : "r" (ptr), "Ir" (old), "r" (new) + : "memory", "cc"); + } while (res); + break; + case 2: + do { + asm volatile("@ __cmpxchg1\n" + " ldrexh %1, [%2]\n" + " mov %0, #0\n" + " teq %1, %3\n" + " strexheq %0, %4, [%2]\n" + : "=&r" (res), "=&r" (oldval) + : "r" (ptr), "Ir" (old), "r" (new) + : "memory", "cc"); + } while (res); + break; +#endif /* CONFIG_CPU_32v6K */ + case 4: + do { + asm volatile("@ __cmpxchg4\n" + " ldrex %1, [%2]\n" + " mov %0, #0\n" + " teq %1, %3\n" + " strexeq %0, %4, [%2]\n" + : "=&r" (res), "=&r" (oldval) + : "r" (ptr), "Ir" (old), "r" (new) + : "memory", "cc"); + } while (res); + break; + default: + __bad_cmpxchg(ptr, size); + oldval = 0; + } + + return oldval; +} + +static inline unsigned long __cmpxchg_mb(volatile void *ptr, unsigned long old, + unsigned long new, int size) +{ + unsigned long ret; + + smp_mb(); + ret = __cmpxchg(ptr, old, new, size); + smp_mb(); + + return ret; +} + +#define cmpxchg(ptr,o,n) \ + ((__typeof__(*(ptr)))__cmpxchg_mb((ptr), \ + (unsigned long)(o), \ + (unsigned long)(n), \ + sizeof(*(ptr)))) + +static inline unsigned long __cmpxchg_local(volatile void *ptr, + unsigned long old, + unsigned long new, int size) +{ + unsigned long ret; + + switch (size) { +#ifndef CONFIG_CPU_32v6K + case 1: + case 2: + ret = __cmpxchg_local_generic(ptr, old, new, size); + break; +#endif /* !CONFIG_CPU_32v6K */ + default: + ret = __cmpxchg(ptr, old, new, size); + } + + return ret; +} + +#define cmpxchg_local(ptr,o,n) \ + ((__typeof__(*(ptr)))__cmpxchg_local((ptr), \ + (unsigned long)(o), \ + (unsigned long)(n), \ + sizeof(*(ptr)))) + +#ifdef CONFIG_CPU_32v6K + +/* + * Note : ARMv7-M (currently unsupported by Linux) does not support + * ldrexd/strexd. If ARMv7-M is ever supported by the Linux kernel, it should + * not be allowed to use __cmpxchg64. + */ +static inline unsigned long long __cmpxchg64(volatile void *ptr, + unsigned long long old, + unsigned long long new) +{ + register unsigned long long oldval asm("r0"); + register unsigned long long __old asm("r2") = old; + register unsigned long long __new asm("r4") = new; + unsigned long res; + + do { + asm volatile( + " @ __cmpxchg8\n" + " ldrexd %1, %H1, [%2]\n" + " mov %0, #0\n" + " teq %1, %3\n" + " teqeq %H1, %H3\n" + " strexdeq %0, %4, %H4, [%2]\n" + : "=&r" (res), "=&r" (oldval) + : "r" (ptr), "Ir" (__old), "r" (__new) + : "memory", "cc"); + } while (res); + + return oldval; +} + +static inline unsigned long long __cmpxchg64_mb(volatile void *ptr, + unsigned long long old, + unsigned long long new) +{ + unsigned long long ret; + + smp_mb(); + ret = __cmpxchg64(ptr, old, new); + smp_mb(); + + return ret; +} + +#define cmpxchg64(ptr,o,n) \ + ((__typeof__(*(ptr)))__cmpxchg64_mb((ptr), \ + (unsigned long long)(o), \ + (unsigned long long)(n))) + +#define cmpxchg64_local(ptr,o,n) \ + ((__typeof__(*(ptr)))__cmpxchg64((ptr), \ + (unsigned long long)(o), \ + (unsigned long long)(n))) + +#else /* !CONFIG_CPU_32v6K */ + +#define cmpxchg64_local(ptr, o, n) __cmpxchg64_local_generic((ptr), (o), (n)) + +#endif /* CONFIG_CPU_32v6K */ + +#endif /* __LINUX_ARM_ARCH__ >= 6 */ + #endif /* __ASSEMBLY__ */ #define arch_align_stack(x) (x) |