LXR linux/arch/arc/include/asm/atomic.h

   1/*
   2 * Copyright (C) 2004, 2007-2010, 2011-2012 Synopsys, Inc. (www.synopsys.com)
   3 *
   4 * This program is free software; you can redistribute it and/or modify
   5 * it under the terms of the GNU General Public License version 2 as
   6 * published by the Free Software Foundation.
   7 */
   8
   9#ifndef _ASM_ARC_ATOMIC_H
  10#define _ASM_ARC_ATOMIC_H
  11
  12#ifndef __ASSEMBLY__
  13
  14#include <linux/types.h>
  15#include <linux/compiler.h>
  16#include <asm/cmpxchg.h>
  17#include <asm/barrier.h>
  18#include <asm/smp.h>
  19
  20#define atomic_read(v)  ((v)->counter)
  21
  22#ifdef CONFIG_ARC_HAS_LLSC
  23
  24#define atomic_set(v, i) (((v)->counter) = (i))
  25
  26#ifdef CONFIG_ARC_STAR_9000923308
  27
  28#define SCOND_FAIL_RETRY_VAR_DEF                                                \
  29        unsigned int delay = 1, tmp;                                            \
  30
  31#define SCOND_FAIL_RETRY_ASM                                                    \
  32        "       bz      4f                      \n"                             \
  33        "   ; --- scond fail delay ---          \n"                             \
  34        "       mov     %[tmp], %[delay]        \n"     /* tmp = delay */       \
  35        "2:     brne.d  %[tmp], 0, 2b           \n"     /* while (tmp != 0) */  \
  36        "       sub     %[tmp], %[tmp], 1       \n"     /* tmp-- */             \
  37        "       rol     %[delay], %[delay]      \n"     /* delay *= 2 */        \
  38        "       b       1b                      \n"     /* start over */        \
  39        "4: ; --- success ---                   \n"                             \
  40
  41#define SCOND_FAIL_RETRY_VARS                                                   \
  42          ,[delay] "+&r" (delay),[tmp] "=&r"    (tmp)                           \
  43
  44#else   /* !CONFIG_ARC_STAR_9000923308 */
  45
  46#define SCOND_FAIL_RETRY_VAR_DEF
  47
  48#define SCOND_FAIL_RETRY_ASM                                                    \
  49        "       bnz     1b                      \n"                             \
  50
  51#define SCOND_FAIL_RETRY_VARS
  52
  53#endif
  54
  55#define ATOMIC_OP(op, c_op, asm_op)                                     \
  56static inline void atomic_##op(int i, atomic_t *v)                      \
  57{                                                                       \
  58        unsigned int val;                                               \
  59        SCOND_FAIL_RETRY_VAR_DEF                                        \
  60                                                                        \
  61        __asm__ __volatile__(                                           \
  62        "1:     llock   %[val], [%[ctr]]                \n"             \
  63        "       " #asm_op " %[val], %[val], %[i]        \n"             \
  64        "       scond   %[val], [%[ctr]]                \n"             \
  65        "                                               \n"             \
  66        SCOND_FAIL_RETRY_ASM                                            \
  67                                                                        \
  68        : [val] "=&r"   (val) /* Early clobber to prevent reg reuse */  \
  69          SCOND_FAIL_RETRY_VARS                                         \
  70        : [ctr] "r"     (&v->counter), /* Not "m": llock only supports reg direct addr mode */  \
  71          [i]   "ir"    (i)                                             \
  72        : "cc");                                                        \
  73}                                                                       \
  74
  75#define ATOMIC_OP_RETURN(op, c_op, asm_op)                              \
  76static inline int atomic_##op##_return(int i, atomic_t *v)              \
  77{                                                                       \
  78        unsigned int val;                                               \
  79        SCOND_FAIL_RETRY_VAR_DEF                                        \
  80                                                                        \
  81        /*                                                              \
  82         * Explicit full memory barrier needed before/after as          \
  83         * LLOCK/SCOND thmeselves don't provide any such semantics      \
  84         */                                                             \
  85        smp_mb();                                                       \
  86                                                                        \
  87        __asm__ __volatile__(                                           \
  88        "1:     llock   %[val], [%[ctr]]                \n"             \
  89        "       " #asm_op " %[val], %[val], %[i]        \n"             \
  90        "       scond   %[val], [%[ctr]]                \n"             \
  91        "                                               \n"             \
  92        SCOND_FAIL_RETRY_ASM                                            \
  93                                                                        \
  94        : [val] "=&r"   (val)                                           \
  95          SCOND_FAIL_RETRY_VARS                                         \
  96        : [ctr] "r"     (&v->counter),                                  \
  97          [i]   "ir"    (i)                                             \
  98        : "cc");                                                        \
  99                                                                        \
 100        smp_mb();                                                       \
 101                                                                        \
 102        return val;                                                     \
 103}
 104
 105#else   /* !CONFIG_ARC_HAS_LLSC */
 106
 107#ifndef CONFIG_SMP
 108
 109 /* violating atomic_xxx API locking protocol in UP for optimization sake */
 110#define atomic_set(v, i) (((v)->counter) = (i))
 111
 112#else
 113
 114static inline void atomic_set(atomic_t *v, int i)
 115{
 116        /*
 117         * Independent of hardware support, all of the atomic_xxx() APIs need
 118         * to follow the same locking rules to make sure that a "hardware"
 119         * atomic insn (e.g. LD) doesn't clobber an "emulated" atomic insn
 120         * sequence
 121         *
 122         * Thus atomic_set() despite being 1 insn (and seemingly atomic)
 123         * requires the locking.
 124         */
 125        unsigned long flags;
 126
 127        atomic_ops_lock(flags);
 128        v->counter = i;
 129        atomic_ops_unlock(flags);
 130}
 131
 132#endif
 133
 134/*
 135 * Non hardware assisted Atomic-R-M-W
 136 * Locking would change to irq-disabling only (UP) and spinlocks (SMP)
 137 */
 138
 139#define ATOMIC_OP(op, c_op, asm_op)                                     \
 140static inline void atomic_##op(int i, atomic_t *v)                      \
 141{                                                                       \
 142        unsigned long flags;                                            \
 143                                                                        \
 144        atomic_ops_lock(flags);                                         \
 145        v->counter c_op i;                                              \
 146        atomic_ops_unlock(flags);                                       \
 147}
 148
 149#define ATOMIC_OP_RETURN(op, c_op, asm_op)                              \
 150static inline int atomic_##op##_return(int i, atomic_t *v)              \
 151{                                                                       \
 152        unsigned long flags;                                            \
 153        unsigned long temp;                                             \
 154                                                                        \
 155        /*                                                              \
 156         * spin lock/unlock provides the needed smp_mb() before/after   \
 157         */                                                             \
 158        atomic_ops_lock(flags);                                         \
 159        temp = v->counter;                                              \
 160        temp c_op i;                                                    \
 161        v->counter = temp;                                              \
 162        atomic_ops_unlock(flags);                                       \
 163                                                                        \
 164        return temp;                                                    \
 165}
 166
 167#endif /* !CONFIG_ARC_HAS_LLSC */
 168
 169#define ATOMIC_OPS(op, c_op, asm_op)                                    \
 170        ATOMIC_OP(op, c_op, asm_op)                                     \
 171        ATOMIC_OP_RETURN(op, c_op, asm_op)
 172
 173ATOMIC_OPS(add, +=, add)
 174ATOMIC_OPS(sub, -=, sub)
 175
 176#define atomic_andnot atomic_andnot
 177
 178ATOMIC_OP(and, &=, and)
 179ATOMIC_OP(andnot, &= ~, bic)
 180ATOMIC_OP(or, |=, or)
 181ATOMIC_OP(xor, ^=, xor)
 182
 183#undef ATOMIC_OPS
 184#undef ATOMIC_OP_RETURN
 185#undef ATOMIC_OP
 186#undef SCOND_FAIL_RETRY_VAR_DEF
 187#undef SCOND_FAIL_RETRY_ASM
 188#undef SCOND_FAIL_RETRY_VARS
 189
 190/**
 191 * __atomic_add_unless - add unless the number is a given value
 192 * @v: pointer of type atomic_t
 193 * @a: the amount to add to v...
 194 * @u: ...unless v is equal to u.
 195 *
 196 * Atomically adds @a to @v, so long as it was not @u.
 197 * Returns the old value of @v
 198 */
 199#define __atomic_add_unless(v, a, u)                                    \
 200({                                                                      \
 201        int c, old;                                                     \
 202                                                                        \
 203        /*                                                              \
 204         * Explicit full memory barrier needed before/after as          \
 205         * LLOCK/SCOND thmeselves don't provide any such semantics      \
 206         */                                                             \
 207        smp_mb();                                                       \
 208                                                                        \
 209        c = atomic_read(v);                                             \
 210        while (c != (u) && (old = atomic_cmpxchg((v), c, c + (a))) != c)\
 211                c = old;                                                \
 212                                                                        \
 213        smp_mb();                                                       \
 214                                                                        \
 215        c;                                                              \
 216})
 217
 218#define atomic_inc_not_zero(v)          atomic_add_unless((v), 1, 0)
 219
 220#define atomic_inc(v)                   atomic_add(1, v)
 221#define atomic_dec(v)                   atomic_sub(1, v)
 222
 223#define atomic_inc_and_test(v)          (atomic_add_return(1, v) == 0)
 224#define atomic_dec_and_test(v)          (atomic_sub_return(1, v) == 0)
 225#define atomic_inc_return(v)            atomic_add_return(1, (v))
 226#define atomic_dec_return(v)            atomic_sub_return(1, (v))
 227#define atomic_sub_and_test(i, v)       (atomic_sub_return(i, v) == 0)
 228
 229#define atomic_add_negative(i, v)       (atomic_add_return(i, v) < 0)
 230
 231#define ATOMIC_INIT(i)                  { (i) }
 232
 233#include <asm-generic/atomic64.h>
 234
 235#endif
 236
 237#endif
 238