kernel/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)                                     \
  27 static 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)                              \
  42 static inline int atomic_##op##_return(int i, atomic_t *v)              \
  43 {                                                                       \
  44         unsigned int temp;                                              \
  45                                                                         \
  46         /*                                                              \
  47          * Explicit full memory barrier needed before/after as          \
  48          * LLOCK/SCOND thmeselves don't provide any such semantics      \
  49          */                                                             \
  50         smp_mb();                                                       \
  51                                                                         \
  52         __asm__ __volatile__(                                           \
  53         "1:     llock   %0, [%1]        \n"                             \
  54         "       " #asm_op " %0, %0, %2  \n"                             \
  55         "       scond   %0, [%1]        \n"                             \
  56         "       bnz     1b              \n"                             \
  57         : "=&r"(temp)                                                   \
  58         : "r"(&v->counter), "ir"(i)                                     \
  59         : "cc");                                                        \
  60                                                                         \
  61         smp_mb();                                                       \
  62                                                                         \
  63         return temp;                                                    \
  64 }
  65
  66 #else   /* !CONFIG_ARC_HAS_LLSC */
  67
  68 #ifndef CONFIG_SMP
  69
  70  /* violating atomic_xxx API locking protocol in UP for optimization sake */
  71 #define atomic_set(v, i) (((v)->counter) = (i))
  72
  73 #else
  74
  75 static inline void atomic_set(atomic_t *v, int i)
  76 {
  77         /*
  78          * Independent of hardware support, all of the atomic_xxx() APIs need
  79          * to follow the same locking rules to make sure that a "hardware"
  80          * atomic insn (e.g. LD) doesn't clobber an "emulated" atomic insn
  81          * sequence
  82          *
  83          * Thus atomic_set() despite being 1 insn (and seemingly atomic)
  84          * requires the locking.
  85          */
  86         unsigned long flags;
  87
  88         atomic_ops_lock(flags);
  89         v->counter = i;
  90         atomic_ops_unlock(flags);
  91 }
  92
  93 #endif
  94
  95 /*
  96  * Non hardware assisted Atomic-R-M-W
  97  * Locking would change to irq-disabling only (UP) and spinlocks (SMP)
  98  */
  99
 100 #define ATOMIC_OP(op, c_op, asm_op)                                     \
 101 static inline void atomic_##op(int i, atomic_t *v)                      \
 102 {                                                                       \
 103         unsigned long flags;                                            \
 104                                                                         \
 105         atomic_ops_lock(flags);                                         \
 106         v->counter c_op i;                                              \
 107         atomic_ops_unlock(flags);                                       \
 108 }
 109
 110 #define ATOMIC_OP_RETURN(op, c_op, asm_op)                              \
 111 static inline int atomic_##op##_return(int i, atomic_t *v)              \
 112 {                                                                       \
 113         unsigned long flags;                                            \
 114         unsigned long temp;                                             \
 115                                                                         \
 116         /*                                                              \
 117          * spin lock/unlock provides the needed smp_mb() before/after   \
 118          */                                                             \
 119         atomic_ops_lock(flags);                                         \
 120         temp = v->counter;                                              \
 121         temp c_op i;                                                    \
 122         v->counter = temp;                                              \
 123         atomic_ops_unlock(flags);                                       \
 124                                                                         \
 125         return temp;                                                    \
 126 }
 127
 128 #endif /* !CONFIG_ARC_HAS_LLSC */
 129
 130 #define ATOMIC_OPS(op, c_op, asm_op)                                    \
 131         ATOMIC_OP(op, c_op, asm_op)                                     \
 132         ATOMIC_OP_RETURN(op, c_op, asm_op)
 133
 134 ATOMIC_OPS(add, +=, add)
 135 ATOMIC_OPS(sub, -=, sub)
 136 ATOMIC_OP(and, &=, and)
 137
 138 #define atomic_clear_mask(mask, v) atomic_and(~(mask), (v))
 139
 140 #undef ATOMIC_OPS
 141 #undef ATOMIC_OP_RETURN
 142 #undef ATOMIC_OP
 143
 144 /**
 145  * __atomic_add_unless - add unless the number is a given value
 146  * @v: pointer of type atomic_t
 147  * @a: the amount to add to v...
 148  * @u: ...unless v is equal to u.
 149  *
 150  * Atomically adds @a to @v, so long as it was not @u.
 151  * Returns the old value of @v
 152  */
 153 #define __atomic_add_unless(v, a, u)                                    \
 154 ({                                                                      \
 155         int c, old;                                                     \
 156                                                                         \
 157         /*                                                              \
 158          * Explicit full memory barrier needed before/after as          \
 159          * LLOCK/SCOND thmeselves don't provide any such semantics      \
 160          */                                                             \
 161         smp_mb();                                                       \
 162                                                                         \
 163         c = atomic_read(v);                                             \
 164         while (c != (u) && (old = atomic_cmpxchg((v), c, c + (a))) != c)\
 165                 c = old;                                                \
 166                                                                         \
 167         smp_mb();                                                       \
 168                                                                         \
 169         c;                                                              \
 170 })
 171
 172 #define atomic_inc_not_zero(v)          atomic_add_unless((v), 1, 0)
 173
 174 #define atomic_inc(v)                   atomic_add(1, v)
 175 #define atomic_dec(v)                   atomic_sub(1, v)
 176
 177 #define atomic_inc_and_test(v)          (atomic_add_return(1, v) == 0)
 178 #define atomic_dec_and_test(v)          (atomic_sub_return(1, v) == 0)
 179 #define atomic_inc_return(v)            atomic_add_return(1, (v))
 180 #define atomic_dec_return(v)            atomic_sub_return(1, (v))
 181 #define atomic_sub_and_test(i, v)       (atomic_sub_return(i, v) == 0)
 182
 183 #define atomic_add_negative(i, v)       (atomic_add_return(i, v) < 0)
 184
 185 #define ATOMIC_INIT(i)                  { (i) }
 186
 187 #include <asm-generic/atomic64.h>
 188
 189 #endif
 190
 191 #endif