projects / linux.git / blame
| Commit | Line | Data |
|---|---|---|
| b4816afa DH |
1 | /* |
| 2 | * Generic UP xchg and cmpxchg using interrupt disablement. Does not | |
| 3 | * support SMP. | |
| 4 | */ | |
| 5 | ||
| 068fbad2 MD |
6 | #ifndef __ASM_GENERIC_CMPXCHG_H |
| 7 | #define __ASM_GENERIC_CMPXCHG_H | |
| 8 | ||
| 068fbad2 MD |
9 | #ifdef CONFIG_SMP |
| 10 | #error "Cannot use generic cmpxchg on SMP" | |
| 11 | #endif | |
| 12 | ||
| 80da6a4f | 13 | #include <linux/types.h> |
| b4816afa DH |
14 | #include <linux/irqflags.h> |
| 15 | ||
| 16 | #ifndef xchg | |
| 17 | ||
| 18 | /* | |
| 19 | * This function doesn't exist, so you'll get a linker error if | |
| 20 | * something tries to do an invalidly-sized xchg(). | |
| 21 | */ | |
| 22 | extern void __xchg_called_with_bad_pointer(void); | |
| 23 | ||
| 24 | static inline | |
| 25 | unsigned long __xchg(unsigned long x, volatile void *ptr, int size) | |
| 26 | { | |
| 27 | unsigned long ret, flags; | |
| 28 | ||
| 29 | switch (size) { | |
| 30 | case 1: | |
| 31 | #ifdef __xchg_u8 | |
| 32 | return __xchg_u8(x, ptr); | |
| 33 | #else | |
| 34 | local_irq_save(flags); | |
| 35 | ret = *(volatile u8 *)ptr; | |
| 36 | *(volatile u8 *)ptr = x; | |
| 37 | local_irq_restore(flags); | |
| 38 | return ret; | |
| 39 | #endif /* __xchg_u8 */ | |
| 40 | ||
| 41 | case 2: | |
| 42 | #ifdef __xchg_u16 | |
| 43 | return __xchg_u16(x, ptr); | |
| 44 | #else | |
| 45 | local_irq_save(flags); | |
| 46 | ret = *(volatile u16 *)ptr; | |
| 47 | *(volatile u16 *)ptr = x; | |
| 48 | local_irq_restore(flags); | |
| 49 | return ret; | |
| 50 | #endif /* __xchg_u16 */ | |
| 51 | ||
| 52 | case 4: | |
| 53 | #ifdef __xchg_u32 | |
| 54 | return __xchg_u32(x, ptr); | |
| 55 | #else | |
| 56 | local_irq_save(flags); | |
| 57 | ret = *(volatile u32 *)ptr; | |
| 58 | *(volatile u32 *)ptr = x; | |
| 59 | local_irq_restore(flags); | |
| 60 | return ret; | |
| 61 | #endif /* __xchg_u32 */ | |
| 62 | ||
| 63 | #ifdef CONFIG_64BIT | |
| 64 | case 8: | |
| 65 | #ifdef __xchg_u64 | |
| 66 | return __xchg_u64(x, ptr); | |
| 67 | #else | |
| 68 | local_irq_save(flags); | |
| 69 | ret = *(volatile u64 *)ptr; | |
| 70 | *(volatile u64 *)ptr = x; | |
| 71 | local_irq_restore(flags); | |
| 72 | return ret; | |
| 73 | #endif /* __xchg_u64 */ | |
| 74 | #endif /* CONFIG_64BIT */ | |
| 75 | ||
| 76 | default: | |
| 77 | __xchg_called_with_bad_pointer(); | |
| 78 | return x; | |
| 79 | } | |
| 80 | } | |
| 81 | ||
| 82 | #define xchg(ptr, x) \ | |
| 83 | ((__typeof__(*(ptr))) __xchg((unsigned long)(x), (ptr), sizeof(*(ptr)))) | |
| 84 | ||
| 85 | #endif /* xchg */ | |
| 34484277 | 86 | |
| 068fbad2 MD |
87 | /* |
| 88 | * Atomic compare and exchange. | |
| 89 | * | |
| 90 | * Do not define __HAVE_ARCH_CMPXCHG because we want to use it to check whether | |
| 91 | * a cmpxchg primitive faster than repeated local irq save/restore exists. | |
| 92 | */ | |
| b4816afa DH |
93 | #include <asm-generic/cmpxchg-local.h> |
| 94 | ||
| 068fbad2 MD |
95 | #define cmpxchg(ptr, o, n) cmpxchg_local((ptr), (o), (n)) |
| 96 | #define cmpxchg64(ptr, o, n) cmpxchg64_local((ptr), (o), (n)) | |
| 97 | ||
| b4816afa | 98 | #endif /* __ASM_GENERIC_CMPXCHG_H */ |