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/prefetch.h> 16 #include <linux/types.h> 17 #include <linux/irqflags.h> 18 #include <asm/barrier.h> 19 #include <asm/cmpxchg.h> 20 21 #define ATOMIC_INIT(i) { (i) } 22 23 #ifdef __KERNEL__ 24 25 /* 26 * On ARM, ordinary assignment (str instruction) doesn't clear the local 27 * strex/ldrex monitor on some implementations. The reason we can use it for 28 * atomic_set() is the clrex or dummy strex done on every exception return. 29 */ 30 #define atomic_read(v) (*(volatile int *)&(v)->counter) 31 #define atomic_set(v,i) (((v)->counter) = (i)) 32 33 #if __LINUX_ARM_ARCH__ >= 6 34 35 /* 36 * ARMv6 UP and SMP safe atomic ops. We use load exclusive and 37 * store exclusive to ensure that these are atomic. We may loop 38 * to ensure that the update happens. 39 */ 40 static inline void atomic_add(int i, atomic_t *v) 41 { 42 unsigned long tmp; 43 int result; 44 45 prefetchw(&v->counter); 46 __asm__ __volatile__("@ atomic_add\n" 47 "1: ldrex %0, [%3]\n" 48 " add %0, %0, %4\n" 49 " strex %1, %0, [%3]\n" 50 " teq %1, #0\n" 51 " bne 1b" 52 : "=&r" (result), "=&r" (tmp), "+Qo" (v->counter) 53 : "r" (&v->counter), "Ir" (i) 54 : "cc"); 55 } 56 57 static inline int atomic_add_return(int i, atomic_t *v) 58 { 59 unsigned long tmp; 60 int result; 61 62 smp_mb(); 63 prefetchw(&v->counter); 64 65 __asm__ __volatile__("@ atomic_add_return\n" 66 "1: ldrex %0, [%3]\n" 67 " add %0, %0, %4\n" 68 " strex %1, %0, [%3]\n" 69 " teq %1, #0\n" 70 " bne 1b" 71 : "=&r" (result), "=&r" (tmp), "+Qo" (v->counter) 72 : "r" (&v->counter), "Ir" (i) 73 : "cc"); 74 75 smp_mb(); 76 77 return result; 78 } 79 80 static inline void atomic_sub(int i, atomic_t *v) 81 { 82 unsigned long tmp; 83 int result; 84 85 prefetchw(&v->counter); 86 __asm__ __volatile__("@ atomic_sub\n" 87 "1: ldrex %0, [%3]\n" 88 " sub %0, %0, %4\n" 89 " strex %1, %0, [%3]\n" 90 " teq %1, #0\n" 91 " bne 1b" 92 : "=&r" (result), "=&r" (tmp), "+Qo" (v->counter) 93 : "r" (&v->counter), "Ir" (i) 94 : "cc"); 95 } 96 97 static inline int atomic_sub_return(int i, atomic_t *v) 98 { 99 unsigned long tmp; 100 int result; 101 102 smp_mb(); 103 prefetchw(&v->counter); 104 105 __asm__ __volatile__("@ atomic_sub_return\n" 106 "1: ldrex %0, [%3]\n" 107 " sub %0, %0, %4\n" 108 " strex %1, %0, [%3]\n" 109 " teq %1, #0\n" 110 " bne 1b" 111 : "=&r" (result), "=&r" (tmp), "+Qo" (v->counter) 112 : "r" (&v->counter), "Ir" (i) 113 : "cc"); 114 115 smp_mb(); 116 117 return result; 118 } 119 120 static inline int atomic_cmpxchg(atomic_t *ptr, int old, int new) 121 { 122 int oldval; 123 unsigned long res; 124 125 smp_mb(); 126 prefetchw(&ptr->counter); 127 128 do { 129 __asm__ __volatile__("@ atomic_cmpxchg\n" 130 "ldrex %1, [%3]\n" 131 "mov %0, #0\n" 132 "teq %1, %4\n" 133 "strexeq %0, %5, [%3]\n" 134 : "=&r" (res), "=&r" (oldval), "+Qo" (ptr->counter) 135 : "r" (&ptr->counter), "Ir" (old), "r" (new) 136 : "cc"); 137 } while (res); 138 139 smp_mb(); 140 141 return oldval; 142 } 143 144 static inline int __atomic_add_unless(atomic_t *v, int a, int u) 145 { 146 int oldval, newval; 147 unsigned long tmp; 148 149 smp_mb(); 150 prefetchw(&v->counter); 151 152 __asm__ __volatile__ ("@ atomic_add_unless\n" 153 "1: ldrex %0, [%4]\n" 154 " teq %0, %5\n" 155 " beq 2f\n" 156 " add %1, %0, %6\n" 157 " strex %2, %1, [%4]\n" 158 " teq %2, #0\n" 159 " bne 1b\n" 160 "2:" 161 : "=&r" (oldval), "=&r" (newval), "=&r" (tmp), "+Qo" (v->counter) 162 : "r" (&v->counter), "r" (u), "r" (a) 163 : "cc"); 164 165 if (oldval != u) 166 smp_mb(); 167 168 return oldval; 169 } 170 171 #else /* ARM_ARCH_6 */ 172 173 #ifdef CONFIG_SMP 174 #error SMP not supported on pre-ARMv6 CPUs 175 #endif 176 177 static inline int atomic_add_return(int i, atomic_t *v) 178 { 179 unsigned long flags; 180 int val; 181 182 raw_local_irq_save(flags); 183 val = v->counter; 184 v->counter = val += i; 185 raw_local_irq_restore(flags); 186 187 return val; 188 } 189 #define atomic_add(i, v) (void) atomic_add_return(i, v) 190 191 static inline int atomic_sub_return(int i, atomic_t *v) 192 { 193 unsigned long flags; 194 int val; 195 196 raw_local_irq_save(flags); 197 val = v->counter; 198 v->counter = val -= i; 199 raw_local_irq_restore(flags); 200 201 return val; 202 } 203 #define atomic_sub(i, v) (void) atomic_sub_return(i, v) 204 205 static inline int atomic_cmpxchg(atomic_t *v, int old, int new) 206 { 207 int ret; 208 unsigned long flags; 209 210 raw_local_irq_save(flags); 211 ret = v->counter; 212 if (likely(ret == old)) 213 v->counter = new; 214 raw_local_irq_restore(flags); 215 216 return ret; 217 } 218 219 static inline int __atomic_add_unless(atomic_t *v, int a, int u) 220 { 221 int c, old; 222 223 c = atomic_read(v); 224 while (c != u && (old = atomic_cmpxchg((v), c, c + a)) != c) 225 c = old; 226 return c; 227 } 228 229 #endif /* __LINUX_ARM_ARCH__ */ 230 231 #define atomic_xchg(v, new) (xchg(&((v)->counter), new)) 232 233 #define atomic_inc(v) atomic_add(1, v) 234 #define atomic_dec(v) atomic_sub(1, v) 235 236 #define atomic_inc_and_test(v) (atomic_add_return(1, v) == 0) 237 #define atomic_dec_and_test(v) (atomic_sub_return(1, v) == 0) 238 #define atomic_inc_return(v) (atomic_add_return(1, v)) 239 #define atomic_dec_return(v) (atomic_sub_return(1, v)) 240 #define atomic_sub_and_test(i, v) (atomic_sub_return(i, v) == 0) 241 242 #define atomic_add_negative(i,v) (atomic_add_return(i, v) < 0) 243 244 #define smp_mb__before_atomic_dec() smp_mb() 245 #define smp_mb__after_atomic_dec() smp_mb() 246 #define smp_mb__before_atomic_inc() smp_mb() 247 #define smp_mb__after_atomic_inc() smp_mb() 248 249 #ifndef CONFIG_GENERIC_ATOMIC64 250 typedef struct { 251 long long counter; 252 } atomic64_t; 253 254 #define ATOMIC64_INIT(i) { (i) } 255 256 #ifdef CONFIG_ARM_LPAE 257 static inline long long atomic64_read(const atomic64_t *v) 258 { 259 long long result; 260 261 __asm__ __volatile__("@ atomic64_read\n" 262 " ldrd %0, %H0, [%1]" 263 : "=&r" (result) 264 : "r" (&v->counter), "Qo" (v->counter) 265 ); 266 267 return result; 268 } 269 270 static inline void atomic64_set(atomic64_t *v, long long i) 271 { 272 __asm__ __volatile__("@ atomic64_set\n" 273 " strd %2, %H2, [%1]" 274 : "=Qo" (v->counter) 275 : "r" (&v->counter), "r" (i) 276 ); 277 } 278 #else 279 static inline long long atomic64_read(const atomic64_t *v) 280 { 281 long long result; 282 283 __asm__ __volatile__("@ atomic64_read\n" 284 " ldrexd %0, %H0, [%1]" 285 : "=&r" (result) 286 : "r" (&v->counter), "Qo" (v->counter) 287 ); 288 289 return result; 290 } 291 292 static inline void atomic64_set(atomic64_t *v, long long i) 293 { 294 long long tmp; 295 296 prefetchw(&v->counter); 297 __asm__ __volatile__("@ atomic64_set\n" 298 "1: ldrexd %0, %H0, [%2]\n" 299 " strexd %0, %3, %H3, [%2]\n" 300 " teq %0, #0\n" 301 " bne 1b" 302 : "=&r" (tmp), "=Qo" (v->counter) 303 : "r" (&v->counter), "r" (i) 304 : "cc"); 305 } 306 #endif 307 308 static inline void atomic64_add(long long i, atomic64_t *v) 309 { 310 long long result; 311 unsigned long tmp; 312 313 prefetchw(&v->counter); 314 __asm__ __volatile__("@ atomic64_add\n" 315 "1: ldrexd %0, %H0, [%3]\n" 316 " adds %Q0, %Q0, %Q4\n" 317 " adc %R0, %R0, %R4\n" 318 " strexd %1, %0, %H0, [%3]\n" 319 " teq %1, #0\n" 320 " bne 1b" 321 : "=&r" (result), "=&r" (tmp), "+Qo" (v->counter) 322 : "r" (&v->counter), "r" (i) 323 : "cc"); 324 } 325 326 static inline long long atomic64_add_return(long long i, atomic64_t *v) 327 { 328 long long result; 329 unsigned long tmp; 330 331 smp_mb(); 332 prefetchw(&v->counter); 333 334 __asm__ __volatile__("@ atomic64_add_return\n" 335 "1: ldrexd %0, %H0, [%3]\n" 336 " adds %Q0, %Q0, %Q4\n" 337 " adc %R0, %R0, %R4\n" 338 " strexd %1, %0, %H0, [%3]\n" 339 " teq %1, #0\n" 340 " bne 1b" 341 : "=&r" (result), "=&r" (tmp), "+Qo" (v->counter) 342 : "r" (&v->counter), "r" (i) 343 : "cc"); 344 345 smp_mb(); 346 347 return result; 348 } 349 350 static inline void atomic64_sub(long long i, atomic64_t *v) 351 { 352 long long result; 353 unsigned long tmp; 354 355 prefetchw(&v->counter); 356 __asm__ __volatile__("@ atomic64_sub\n" 357 "1: ldrexd %0, %H0, [%3]\n" 358 " subs %Q0, %Q0, %Q4\n" 359 " sbc %R0, %R0, %R4\n" 360 " strexd %1, %0, %H0, [%3]\n" 361 " teq %1, #0\n" 362 " bne 1b" 363 : "=&r" (result), "=&r" (tmp), "+Qo" (v->counter) 364 : "r" (&v->counter), "r" (i) 365 : "cc"); 366 } 367 368 static inline long long atomic64_sub_return(long long i, atomic64_t *v) 369 { 370 long long result; 371 unsigned long tmp; 372 373 smp_mb(); 374 prefetchw(&v->counter); 375 376 __asm__ __volatile__("@ atomic64_sub_return\n" 377 "1: ldrexd %0, %H0, [%3]\n" 378 " subs %Q0, %Q0, %Q4\n" 379 " sbc %R0, %R0, %R4\n" 380 " strexd %1, %0, %H0, [%3]\n" 381 " teq %1, #0\n" 382 " bne 1b" 383 : "=&r" (result), "=&r" (tmp), "+Qo" (v->counter) 384 : "r" (&v->counter), "r" (i) 385 : "cc"); 386 387 smp_mb(); 388 389 return result; 390 } 391 392 static inline long long atomic64_cmpxchg(atomic64_t *ptr, long long old, 393 long long new) 394 { 395 long long oldval; 396 unsigned long res; 397 398 smp_mb(); 399 prefetchw(&ptr->counter); 400 401 do { 402 __asm__ __volatile__("@ atomic64_cmpxchg\n" 403 "ldrexd %1, %H1, [%3]\n" 404 "mov %0, #0\n" 405 "teq %1, %4\n" 406 "teqeq %H1, %H4\n" 407 "strexdeq %0, %5, %H5, [%3]" 408 : "=&r" (res), "=&r" (oldval), "+Qo" (ptr->counter) 409 : "r" (&ptr->counter), "r" (old), "r" (new) 410 : "cc"); 411 } while (res); 412 413 smp_mb(); 414 415 return oldval; 416 } 417 418 static inline long long atomic64_xchg(atomic64_t *ptr, long long new) 419 { 420 long long result; 421 unsigned long tmp; 422 423 smp_mb(); 424 prefetchw(&ptr->counter); 425 426 __asm__ __volatile__("@ atomic64_xchg\n" 427 "1: ldrexd %0, %H0, [%3]\n" 428 " strexd %1, %4, %H4, [%3]\n" 429 " teq %1, #0\n" 430 " bne 1b" 431 : "=&r" (result), "=&r" (tmp), "+Qo" (ptr->counter) 432 : "r" (&ptr->counter), "r" (new) 433 : "cc"); 434 435 smp_mb(); 436 437 return result; 438 } 439 440 static inline long long atomic64_dec_if_positive(atomic64_t *v) 441 { 442 long long result; 443 unsigned long tmp; 444 445 smp_mb(); 446 prefetchw(&v->counter); 447 448 __asm__ __volatile__("@ atomic64_dec_if_positive\n" 449 "1: ldrexd %0, %H0, [%3]\n" 450 " subs %Q0, %Q0, #1\n" 451 " sbc %R0, %R0, #0\n" 452 " teq %R0, #0\n" 453 " bmi 2f\n" 454 " strexd %1, %0, %H0, [%3]\n" 455 " teq %1, #0\n" 456 " bne 1b\n" 457 "2:" 458 : "=&r" (result), "=&r" (tmp), "+Qo" (v->counter) 459 : "r" (&v->counter) 460 : "cc"); 461 462 smp_mb(); 463 464 return result; 465 } 466 467 static inline int atomic64_add_unless(atomic64_t *v, long long a, long long u) 468 { 469 long long val; 470 unsigned long tmp; 471 int ret = 1; 472 473 smp_mb(); 474 prefetchw(&v->counter); 475 476 __asm__ __volatile__("@ atomic64_add_unless\n" 477 "1: ldrexd %0, %H0, [%4]\n" 478 " teq %0, %5\n" 479 " teqeq %H0, %H5\n" 480 " moveq %1, #0\n" 481 " beq 2f\n" 482 " adds %Q0, %Q0, %Q6\n" 483 " adc %R0, %R0, %R6\n" 484 " strexd %2, %0, %H0, [%4]\n" 485 " teq %2, #0\n" 486 " bne 1b\n" 487 "2:" 488 : "=&r" (val), "+r" (ret), "=&r" (tmp), "+Qo" (v->counter) 489 : "r" (&v->counter), "r" (u), "r" (a) 490 : "cc"); 491 492 if (ret) 493 smp_mb(); 494 495 return ret; 496 } 497 498 #define atomic64_add_negative(a, v) (atomic64_add_return((a), (v)) < 0) 499 #define atomic64_inc(v) atomic64_add(1LL, (v)) 500 #define atomic64_inc_return(v) atomic64_add_return(1LL, (v)) 501 #define atomic64_inc_and_test(v) (atomic64_inc_return(v) == 0) 502 #define atomic64_sub_and_test(a, v) (atomic64_sub_return((a), (v)) == 0) 503 #define atomic64_dec(v) atomic64_sub(1LL, (v)) 504 #define atomic64_dec_return(v) atomic64_sub_return(1LL, (v)) 505 #define atomic64_dec_and_test(v) (atomic64_dec_return((v)) == 0) 506 #define atomic64_inc_not_zero(v) atomic64_add_unless((v), 1LL, 0LL) 507 508 #endif /* !CONFIG_GENERIC_ATOMIC64 */ 509 #endif 510 #endif 511