1 /* 2 * Generic C implementation of atomic counter operations 3 * Originally implemented for MN10300. 4 * 5 * Copyright (C) 2007 Red Hat, Inc. All Rights Reserved. 6 * Written by David Howells (dhowells@redhat.com) 7 * 8 * This program is free software; you can redistribute it and/or 9 * modify it under the terms of the GNU General Public Licence 10 * as published by the Free Software Foundation; either version 11 * 2 of the Licence, or (at your option) any later version. 12 */ 13 #ifndef __ASM_GENERIC_ATOMIC_H 14 #define __ASM_GENERIC_ATOMIC_H 15 16 #ifdef CONFIG_SMP 17 #error not SMP safe 18 #endif 19 20 /* 21 * Atomic operations that C can't guarantee us. Useful for 22 * resource counting etc.. 23 */ 24 25 #define ATOMIC_INIT(i) { (i) } 26 27 #ifdef __KERNEL__ 28 29 /** 30 * atomic_read - read atomic variable 31 * @v: pointer of type atomic_t 32 * 33 * Atomically reads the value of @v. 34 */ 35 #define atomic_read(v) (*(volatile int *)&(v)->counter) 36 37 /** 38 * atomic_set - set atomic variable 39 * @v: pointer of type atomic_t 40 * @i: required value 41 * 42 * Atomically sets the value of @v to @i. 43 */ 44 #define atomic_set(v, i) (((v)->counter) = (i)) 45 46 #include <asm/system.h> 47 48 /** 49 * atomic_add_return - add integer to atomic variable 50 * @i: integer value to add 51 * @v: pointer of type atomic_t 52 * 53 * Atomically adds @i to @v and returns the result 54 */ 55 static inline int atomic_add_return(int i, atomic_t *v) 56 { 57 unsigned long flags; 58 int temp; 59 60 local_irq_save(flags); 61 temp = v->counter; 62 temp += i; 63 v->counter = temp; 64 local_irq_restore(flags); 65 66 return temp; 67 } 68 69 /** 70 * atomic_sub_return - subtract integer from atomic variable 71 * @i: integer value to subtract 72 * @v: pointer of type atomic_t 73 * 74 * Atomically subtracts @i from @v and returns the result 75 */ 76 static inline int atomic_sub_return(int i, atomic_t *v) 77 { 78 unsigned long flags; 79 int temp; 80 81 local_irq_save(flags); 82 temp = v->counter; 83 temp -= i; 84 v->counter = temp; 85 local_irq_restore(flags); 86 87 return temp; 88 } 89 90 static inline int atomic_add_negative(int i, atomic_t *v) 91 { 92 return atomic_add_return(i, v) < 0; 93 } 94 95 static inline void atomic_add(int i, atomic_t *v) 96 { 97 atomic_add_return(i, v); 98 } 99 100 static inline void atomic_sub(int i, atomic_t *v) 101 { 102 atomic_sub_return(i, v); 103 } 104 105 static inline void atomic_inc(atomic_t *v) 106 { 107 atomic_add_return(1, v); 108 } 109 110 static inline void atomic_dec(atomic_t *v) 111 { 112 atomic_sub_return(1, v); 113 } 114 115 #define atomic_dec_return(v) atomic_sub_return(1, (v)) 116 #define atomic_inc_return(v) atomic_add_return(1, (v)) 117 118 #define atomic_sub_and_test(i, v) (atomic_sub_return((i), (v)) == 0) 119 #define atomic_dec_and_test(v) (atomic_sub_return(1, (v)) == 0) 120 #define atomic_inc_and_test(v) (atomic_add_return(1, (v)) == 0) 121 122 #define atomic_add_unless(v, a, u) \ 123 ({ \ 124 int c, old; \ 125 c = atomic_read(v); \ 126 while (c != (u) && (old = atomic_cmpxchg((v), c, c + (a))) != c) \ 127 c = old; \ 128 c != (u); \ 129 }) 130 131 #define atomic_inc_not_zero(v) atomic_add_unless((v), 1, 0) 132 133 static inline void atomic_clear_mask(unsigned long mask, unsigned long *addr) 134 { 135 unsigned long flags; 136 137 mask = ~mask; 138 local_irq_save(flags); 139 *addr &= mask; 140 local_irq_restore(flags); 141 } 142 143 #define atomic_xchg(ptr, v) (xchg(&(ptr)->counter, (v))) 144 #define atomic_cmpxchg(v, old, new) (cmpxchg(&((v)->counter), (old), (new))) 145 146 #define cmpxchg_local(ptr, o, n) \ 147 ((__typeof__(*(ptr)))__cmpxchg_local_generic((ptr), (unsigned long)(o),\ 148 (unsigned long)(n), sizeof(*(ptr)))) 149 150 #define cmpxchg64_local(ptr, o, n) __cmpxchg64_local_generic((ptr), (o), (n)) 151 152 /* Assume that atomic operations are already serializing */ 153 #define smp_mb__before_atomic_dec() barrier() 154 #define smp_mb__after_atomic_dec() barrier() 155 #define smp_mb__before_atomic_inc() barrier() 156 #define smp_mb__after_atomic_inc() barrier() 157 158 #include <asm-generic/atomic-long.h> 159 160 #endif /* __KERNEL__ */ 161 #endif /* __ASM_GENERIC_ATOMIC_H */ 162