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#define ATOMIC_OP(op, c_op, asm_op)                                     \
  27static inline void atomic_##op(int i, atomic_t *v)                      \
  28{                                                                       \
  29        unsigned int temp;                                              \
  30                                                                        \
  31        __asm__ __volatile__(                                           \
  32        "1:     llock   %0, [%1]        \n"                             \
  33        "       " #asm_op " %0, %0, %2  \n"                             \
  34        "       scond   %0, [%1]        \n"                             \
  35        "       bnz     1b              \n"                             \
  36        : "=&r"(temp)   /* Early clobber, to prevent reg reuse */       \
  37        : "r"(&v->counter), "ir"(i)                                     \
  38        : "cc");                                                        \
  39}                                                                       \
  40
  41#define ATOMIC_OP_RETURN(op, c_op, asm_op)                              \
  42static inline int atomic_##op##_return(int i, atomic_t *v)              \
  43{                                                                       \
  44        unsigned int temp;                                              \
  45                                                                        \
  46        __asm__ __volatile__(                                           \
  47        "1:     llock   %0, [%1]        \n"                             \
  48        "       " #asm_op " %0, %0, %2  \n"                             \
  49        "       scond   %0, [%1]        \n"                             \
  50        "       bnz     1b              \n"                             \
  51        : "=&r"(temp)                                                   \
  52        : "r"(&v->counter), "ir"(i)                                     \
  53        : "cc");                                                        \
  54                                                                        \
  55        return temp;                                                    \
  56}
  57
  58#else   /* !CONFIG_ARC_HAS_LLSC */
  59
  60#ifndef CONFIG_SMP
  61
  62 /* violating atomic_xxx API locking protocol in UP for optimization sake */
  63#define atomic_set(v, i) (((v)->counter) = (i))
  64
  65#else
  66
  67static inline void atomic_set(atomic_t *v, int i)
  68{
  69        /*
  70         * Independent of hardware support, all of the atomic_xxx() APIs need
  71         * to follow the same locking rules to make sure that a "hardware"
  72         * atomic insn (e.g. LD) doesn't clobber an "emulated" atomic insn
  73         * sequence
  74         *
  75         * Thus atomic_set() despite being 1 insn (and seemingly atomic)
  76         * requires the locking.
  77         */
  78        unsigned long flags;
  79
  80        atomic_ops_lock(flags);
  81        v->counter = i;
  82        atomic_ops_unlock(flags);
  83}
  84
  85#endif
  86
  87/*
  88 * Non hardware assisted Atomic-R-M-W
  89 * Locking would change to irq-disabling only (UP) and spinlocks (SMP)
  90 */
  91
  92#define ATOMIC_OP(op, c_op, asm_op)                                     \
  93static inline void atomic_##op(int i, atomic_t *v)                      \
  94{                                                                       \
  95        unsigned long flags;                                            \
  96                                                                        \
  97        atomic_ops_lock(flags);                                         \
  98        v->counter c_op i;                                              \
  99        atomic_ops_unlock(flags);                                       \
 100}
 101
 102#define ATOMIC_OP_RETURN(op, c_op, asm_op)                              \
 103static inline int atomic_##op##_return(int i, atomic_t *v)              \
 104{                                                                       \
 105        unsigned long flags;                                            \
 106        unsigned long temp;                                             \
 107                                                                        \
 108        atomic_ops_lock(flags);                                         \
 109        temp = v->counter;                                              \
 110        temp c_op i;                                                    \
 111        v->counter = temp;                                              \
 112        atomic_ops_unlock(flags);                                       \
 113                                                                        \
 114        return temp;                                                    \
 115}
 116
 117#endif /* !CONFIG_ARC_HAS_LLSC */
 118
 119#define ATOMIC_OPS(op, c_op, asm_op)                                    \
 120        ATOMIC_OP(op, c_op, asm_op)                                     \
 121        ATOMIC_OP_RETURN(op, c_op, asm_op)
 122
 123ATOMIC_OPS(add, +=, add)
 124ATOMIC_OPS(sub, -=, sub)
 125ATOMIC_OP(and, &=, and)
 126
 127#define atomic_clear_mask(mask, v) atomic_and(~(mask), (v))
 128
 129#undef ATOMIC_OPS
 130#undef ATOMIC_OP_RETURN
 131#undef ATOMIC_OP
 132
 133/**
 134 * __atomic_add_unless - add unless the number is a given value
 135 * @v: pointer of type atomic_t
 136 * @a: the amount to add to v...
 137 * @u: ...unless v is equal to u.
 138 *
 139 * Atomically adds @a to @v, so long as it was not @u.
 140 * Returns the old value of @v
 141 */
 142#define __atomic_add_unless(v, a, u)                                    \
 143({                                                                      \
 144        int c, old;                                                     \
 145        c = atomic_read(v);                                             \
 146        while (c != (u) && (old = atomic_cmpxchg((v), c, c + (a))) != c)\
 147                c = old;                                                \
 148        c;                                                              \
 149})
 150
 151#define atomic_inc_not_zero(v)          atomic_add_unless((v), 1, 0)
 152
 153#define atomic_inc(v)                   atomic_add(1, v)
 154#define atomic_dec(v)                   atomic_sub(1, v)
 155
 156#define atomic_inc_and_test(v)          (atomic_add_return(1, v) == 0)
 157#define atomic_dec_and_test(v)          (atomic_sub_return(1, v) == 0)
 158#define atomic_inc_return(v)            atomic_add_return(1, (v))
 159#define atomic_dec_return(v)            atomic_sub_return(1, (v))
 160#define atomic_sub_and_test(i, v)       (atomic_sub_return(i, v) == 0)
 161
 162#define atomic_add_negative(i, v)       (atomic_add_return(i, v) < 0)
 163
 164#define ATOMIC_INIT(i)                  { (i) }
 165
 166#include <asm-generic/atomic64.h>
 167
 168#endif
 169
 170#endif
 171