1 /* 2 * arch/arm/include/asm/atomic.h 3 * 4 * Copyright (C) 1996 Russell King. 5 * Copyright (C) 2002 Deep Blue Solutions Ltd. 6 * 7 * This program is free software; you can redistribute it and/or modify 8 * it under the terms of the GNU General Public License version 2 as 9 * published by the Free Software Foundation. 10 */ 11 #ifndef __ASM_ARM_ATOMIC_H 12 #define __ASM_ARM_ATOMIC_H 13 14 #include <linux/compiler.h> 15 #include <linux/types.h> 16 #include <asm/system.h> 17 18 #define ATOMIC_INIT(i) { (i) } 19 20 #ifdef __KERNEL__ 21 22 /* 23 * On ARM, ordinary assignment (str instruction) doesn't clear the local 24 * strex/ldrex monitor on some implementations. The reason we can use it for 25 * atomic_set() is the clrex or dummy strex done on every exception return. 26 */ 27 #define atomic_read(v) ((v)->counter) 28 #define atomic_set(v,i) (((v)->counter) = (i)) 29 30 #if __LINUX_ARM_ARCH__ >= 6 31 32 /* 33 * ARMv6 UP and SMP safe atomic ops. We use load exclusive and 34 * store exclusive to ensure that these are atomic. We may loop 35 * to ensure that the update happens. 36 */ 37 static inline void atomic_add(int i, atomic_t *v) 38 { 39 unsigned long tmp; 40 int result; 41 42 __asm__ __volatile__("@ atomic_add\n" 43 "1: ldrex %0, [%2]\n" 44 " add %0, %0, %3\n" 45 " strex %1, %0, [%2]\n" 46 " teq %1, #0\n" 47 " bne 1b" 48 : "=&r" (result), "=&r" (tmp) 49 : "r" (&v->counter), "Ir" (i) 50 : "cc"); 51 } 52 53 static inline int atomic_add_return(int i, atomic_t *v) 54 { 55 unsigned long tmp; 56 int result; 57 58 smp_mb(); 59 60 __asm__ __volatile__("@ atomic_add_return\n" 61 "1: ldrex %0, [%2]\n" 62 " add %0, %0, %3\n" 63 " strex %1, %0, [%2]\n" 64 " teq %1, #0\n" 65 " bne 1b" 66 : "=&r" (result), "=&r" (tmp) 67 : "r" (&v->counter), "Ir" (i) 68 : "cc"); 69 70 smp_mb(); 71 72 return result; 73 } 74 75 static inline void atomic_sub(int i, atomic_t *v) 76 { 77 unsigned long tmp; 78 int result; 79 80 __asm__ __volatile__("@ atomic_sub\n" 81 "1: ldrex %0, [%2]\n" 82 " sub %0, %0, %3\n" 83 " strex %1, %0, [%2]\n" 84 " teq %1, #0\n" 85 " bne 1b" 86 : "=&r" (result), "=&r" (tmp) 87 : "r" (&v->counter), "Ir" (i) 88 : "cc"); 89 } 90 91 static inline int atomic_sub_return(int i, atomic_t *v) 92 { 93 unsigned long tmp; 94 int result; 95 96 smp_mb(); 97 98 __asm__ __volatile__("@ atomic_sub_return\n" 99 "1: ldrex %0, [%2]\n" 100 " sub %0, %0, %3\n" 101 " strex %1, %0, [%2]\n" 102 " teq %1, #0\n" 103 " bne 1b" 104 : "=&r" (result), "=&r" (tmp) 105 : "r" (&v->counter), "Ir" (i) 106 : "cc"); 107 108 smp_mb(); 109 110 return result; 111 } 112 113 static inline int atomic_cmpxchg(atomic_t *ptr, int old, int new) 114 { 115 unsigned long oldval, res; 116 117 smp_mb(); 118 119 do { 120 __asm__ __volatile__("@ atomic_cmpxchg\n" 121 "ldrex %1, [%2]\n" 122 "mov %0, #0\n" 123 "teq %1, %3\n" 124 "strexeq %0, %4, [%2]\n" 125 : "=&r" (res), "=&r" (oldval) 126 : "r" (&ptr->counter), "Ir" (old), "r" (new) 127 : "cc"); 128 } while (res); 129 130 smp_mb(); 131 132 return oldval; 133 } 134 135 static inline void atomic_clear_mask(unsigned long mask, unsigned long *addr) 136 { 137 unsigned long tmp, tmp2; 138 139 __asm__ __volatile__("@ atomic_clear_mask\n" 140 "1: ldrex %0, [%2]\n" 141 " bic %0, %0, %3\n" 142 " strex %1, %0, [%2]\n" 143 " teq %1, #0\n" 144 " bne 1b" 145 : "=&r" (tmp), "=&r" (tmp2) 146 : "r" (addr), "Ir" (mask) 147 : "cc"); 148 } 149 150 #else /* ARM_ARCH_6 */ 151 152 #ifdef CONFIG_SMP 153 #error SMP not supported on pre-ARMv6 CPUs 154 #endif 155 156 static inline int atomic_add_return(int i, atomic_t *v) 157 { 158 unsigned long flags; 159 int val; 160 161 raw_local_irq_save(flags); 162 val = v->counter; 163 v->counter = val += i; 164 raw_local_irq_restore(flags); 165 166 return val; 167 } 168 #define atomic_add(i, v) (void) atomic_add_return(i, v) 169 170 static inline int atomic_sub_return(int i, atomic_t *v) 171 { 172 unsigned long flags; 173 int val; 174 175 raw_local_irq_save(flags); 176 val = v->counter; 177 v->counter = val -= i; 178 raw_local_irq_restore(flags); 179 180 return val; 181 } 182 #define atomic_sub(i, v) (void) atomic_sub_return(i, v) 183 184 static inline int atomic_cmpxchg(atomic_t *v, int old, int new) 185 { 186 int ret; 187 unsigned long flags; 188 189 raw_local_irq_save(flags); 190 ret = v->counter; 191 if (likely(ret == old)) 192 v->counter = new; 193 raw_local_irq_restore(flags); 194 195 return ret; 196 } 197 198 static inline void atomic_clear_mask(unsigned long mask, unsigned long *addr) 199 { 200 unsigned long flags; 201 202 raw_local_irq_save(flags); 203 *addr &= ~mask; 204 raw_local_irq_restore(flags); 205 } 206 207 #endif /* __LINUX_ARM_ARCH__ */ 208 209 #define atomic_xchg(v, new) (xchg(&((v)->counter), new)) 210 211 static inline int atomic_add_unless(atomic_t *v, int a, int u) 212 { 213 int c, old; 214 215 c = atomic_read(v); 216 while (c != u && (old = atomic_cmpxchg((v), c, c + a)) != c) 217 c = old; 218 return c != u; 219 } 220 #define atomic_inc_not_zero(v) atomic_add_unless((v), 1, 0) 221 222 #define atomic_inc(v) atomic_add(1, v) 223 #define atomic_dec(v) atomic_sub(1, v) 224 225 #define atomic_inc_and_test(v) (atomic_add_return(1, v) == 0) 226 #define atomic_dec_and_test(v) (atomic_sub_return(1, v) == 0) 227 #define atomic_inc_return(v) (atomic_add_return(1, v)) 228 #define atomic_dec_return(v) (atomic_sub_return(1, v)) 229 #define atomic_sub_and_test(i, v) (atomic_sub_return(i, v) == 0) 230 231 #define atomic_add_negative(i,v) (atomic_add_return(i, v) < 0) 232 233 #define smp_mb__before_atomic_dec() smp_mb() 234 #define smp_mb__after_atomic_dec() smp_mb() 235 #define smp_mb__before_atomic_inc() smp_mb() 236 #define smp_mb__after_atomic_inc() smp_mb() 237 238 #include <asm-generic/atomic-long.h> 239 #endif 240 #endif 241