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. Note that the guaranteed 34 * useful range of an atomic_t is only 24 bits. 35 */ 36 #define atomic_read(v) ((v)->counter) 37 38 /** 39 * atomic_set - set atomic variable 40 * @v: pointer of type atomic_t 41 * @i: required value 42 * 43 * Atomically sets the value of @v to @i. Note that the guaranteed 44 * useful range of an atomic_t is only 24 bits. 45 */ 46 #define atomic_set(v, i) (((v)->counter) = (i)) 47 48 #include <asm/system.h> 49 50 /** 51 * atomic_add_return - add integer to atomic variable 52 * @i: integer value to add 53 * @v: pointer of type atomic_t 54 * 55 * Atomically adds @i to @v and returns the result 56 * Note that the guaranteed useful range of an atomic_t is only 24 bits. 57 */ 58 static inline int atomic_add_return(int i, atomic_t *v) 59 { 60 unsigned long flags; 61 int temp; 62 63 local_irq_save(flags); 64 temp = v->counter; 65 temp += i; 66 v->counter = temp; 67 local_irq_restore(flags); 68 69 return temp; 70 } 71 72 /** 73 * atomic_sub_return - subtract integer from atomic variable 74 * @i: integer value to subtract 75 * @v: pointer of type atomic_t 76 * 77 * Atomically subtracts @i from @v and returns the result 78 * Note that the guaranteed useful range of an atomic_t is only 24 bits. 79 */ 80 static inline int atomic_sub_return(int i, atomic_t *v) 81 { 82 unsigned long flags; 83 int temp; 84 85 local_irq_save(flags); 86 temp = v->counter; 87 temp -= i; 88 v->counter = temp; 89 local_irq_restore(flags); 90 91 return temp; 92 } 93 94 static inline int atomic_add_negative(int i, atomic_t *v) 95 { 96 return atomic_add_return(i, v) < 0; 97 } 98 99 static inline void atomic_add(int i, atomic_t *v) 100 { 101 atomic_add_return(i, v); 102 } 103 104 static inline void atomic_sub(int i, atomic_t *v) 105 { 106 atomic_sub_return(i, v); 107 } 108 109 static inline void atomic_inc(atomic_t *v) 110 { 111 atomic_add_return(1, v); 112 } 113 114 static inline void atomic_dec(atomic_t *v) 115 { 116 atomic_sub_return(1, v); 117 } 118 119 #define atomic_dec_return(v) atomic_sub_return(1, (v)) 120 #define atomic_inc_return(v) atomic_add_return(1, (v)) 121 122 #define atomic_sub_and_test(i, v) (atomic_sub_return((i), (v)) == 0) 123 #define atomic_dec_and_test(v) (atomic_sub_return(1, (v)) == 0) 124 #define atomic_inc_and_test(v) (atomic_add_return(1, (v)) == 0) 125 126 #define atomic_add_unless(v, a, u) \ 127 ({ \ 128 int c, old; \ 129 c = atomic_read(v); \ 130 while (c != (u) && (old = atomic_cmpxchg((v), c, c + (a))) != c) \ 131 c = old; \ 132 c != (u); \ 133 }) 134 135 #define atomic_inc_not_zero(v) atomic_add_unless((v), 1, 0) 136 137 static inline void atomic_clear_mask(unsigned long mask, unsigned long *addr) 138 { 139 unsigned long flags; 140 141 mask = ~mask; 142 local_irq_save(flags); 143 *addr &= mask; 144 local_irq_restore(flags); 145 } 146 147 #define atomic_xchg(ptr, v) (xchg(&(ptr)->counter, (v))) 148 #define atomic_cmpxchg(v, old, new) (cmpxchg(&((v)->counter), (old), (new))) 149 150 #define cmpxchg_local(ptr, o, n) \ 151 ((__typeof__(*(ptr)))__cmpxchg_local_generic((ptr), (unsigned long)(o),\ 152 (unsigned long)(n), sizeof(*(ptr)))) 153 154 #define cmpxchg64_local(ptr, o, n) __cmpxchg64_local_generic((ptr), (o), (n)) 155 156 /* Assume that atomic operations are already serializing */ 157 #define smp_mb__before_atomic_dec() barrier() 158 #define smp_mb__after_atomic_dec() barrier() 159 #define smp_mb__before_atomic_inc() barrier() 160 #define smp_mb__after_atomic_inc() barrier() 161 162 #include <asm-generic/atomic-long.h> 163 164 #endif /* __KERNEL__ */ 165 #endif /* __ASM_GENERIC_ATOMIC_H */ 166