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

   1/*
   2 * Atomic operations for the Hexagon architecture
   3 *
   4 * Copyright (c) 2010-2011, Code Aurora Forum. All rights reserved.
   5 *
   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 and
   9 * only version 2 as published by the Free Software Foundation.
  10 *
  11 * This program is distributed in the hope that it will be useful,
  12 * but WITHOUT ANY WARRANTY; without even the implied warranty of
  13 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  14 * GNU General Public License for more details.
  15 *
  16 * You should have received a copy of the GNU General Public License
  17 * along with this program; if not, write to the Free Software
  18 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA
  19 * 02110-1301, USA.
  20 */
  21
  22#ifndef _ASM_ATOMIC_H
  23#define _ASM_ATOMIC_H
  24
  25#include <linux/types.h>
  26#include <asm/cmpxchg.h>
  27
  28#define ATOMIC_INIT(i)          { (i) }
  29#define atomic_set(v, i)        ((v)->counter = (i))
  30
  31/**
  32 * atomic_read - reads a word, atomically
  33 * @v: pointer to atomic value
  34 *
  35 * Assumes all word reads on our architecture are atomic.
  36 */
  37#define atomic_read(v)          ((v)->counter)
  38
  39/**
  40 * atomic_xchg - atomic
  41 * @v: pointer to memory to change
  42 * @new: new value (technically passed in a register -- see xchg)
  43 */
  44#define atomic_xchg(v, new)     (xchg(&((v)->counter), (new)))
  45
  46
  47/**
  48 * atomic_cmpxchg - atomic compare-and-exchange values
  49 * @v: pointer to value to change
  50 * @old:  desired old value to match
  51 * @new:  new value to put in
  52 *
  53 * Parameters are then pointer, value-in-register, value-in-register,
  54 * and the output is the old value.
  55 *
  56 * Apparently this is complicated for archs that don't support
  57 * the memw_locked like we do (or it's broken or whatever).
  58 *
  59 * Kind of the lynchpin of the rest of the generically defined routines.
  60 * Remember V2 had that bug with dotnew predicate set by memw_locked.
  61 *
  62 * "old" is "expected" old val, __oldval is actual old value
  63 */
  64static inline int atomic_cmpxchg(atomic_t *v, int old, int new)
  65{
  66        int __oldval;
  67
  68        asm volatile(
  69                "1:     %0 = memw_locked(%1);\n"
  70                "       { P0 = cmp.eq(%0,%2);\n"
  71                "         if (!P0.new) jump:nt 2f; }\n"
  72                "       memw_locked(%1,P0) = %3;\n"
  73                "       if (!P0) jump 1b;\n"
  74                "2:\n"
  75                : "=&r" (__oldval)
  76                : "r" (&v->counter), "r" (old), "r" (new)
  77                : "memory", "p0"
  78        );
  79
  80        return __oldval;
  81}
  82
  83static inline int atomic_add_return(int i, atomic_t *v)
  84{
  85        int output;
  86
  87        __asm__ __volatile__ (
  88                "1:     %0 = memw_locked(%1);\n"
  89                "       %0 = add(%0,%2);\n"
  90                "       memw_locked(%1,P3)=%0;\n"
  91                "       if !P3 jump 1b;\n"
  92                : "=&r" (output)
  93                : "r" (&v->counter), "r" (i)
  94                : "memory", "p3"
  95        );
  96        return output;
  97
  98}
  99
 100#define atomic_add(i, v) atomic_add_return(i, (v))
 101
 102static inline int atomic_sub_return(int i, atomic_t *v)
 103{
 104        int output;
 105        __asm__ __volatile__ (
 106                "1:     %0 = memw_locked(%1);\n"
 107                "       %0 = sub(%0,%2);\n"
 108                "       memw_locked(%1,P3)=%0\n"
 109                "       if !P3 jump 1b;\n"
 110                : "=&r" (output)
 111                : "r" (&v->counter), "r" (i)
 112                : "memory", "p3"
 113        );
 114        return output;
 115}
 116
 117#define atomic_sub(i, v) atomic_sub_return(i, (v))
 118
 119/**
 120 * atomic_add_unless - add unless the number is a given value
 121 * @v: pointer to value
 122 * @a: amount to add
 123 * @u: unless value is equal to u
 124 *
 125 * Returns 1 if the add happened, 0 if it didn't.
 126 */
 127static inline int __atomic_add_unless(atomic_t *v, int a, int u)
 128{
 129        int output, __oldval;
 130        asm volatile(
 131                "1:     %0 = memw_locked(%2);"
 132                "       {"
 133                "               p3 = cmp.eq(%0, %4);"
 134                "               if (p3.new) jump:nt 2f;"
 135                "               %0 = add(%0, %3);"
 136                "               %1 = #0;"
 137                "       }"
 138                "       memw_locked(%2, p3) = %0;"
 139                "       {"
 140                "               if !p3 jump 1b;"
 141                "               %1 = #1;"
 142                "       }"
 143                "2:"
 144                : "=&r" (__oldval), "=&r" (output)
 145                : "r" (v), "r" (a), "r" (u)
 146                : "memory", "p3"
 147        );
 148        return output;
 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_sub_and_test(i, v) (atomic_sub_return(i, (v)) == 0)
 159#define atomic_add_negative(i, v) (atomic_add_return(i, (v)) < 0)
 160
 161
 162#define atomic_inc_return(v) (atomic_add_return(1, v))
 163#define atomic_dec_return(v) (atomic_sub_return(1, v))
 164
 165#endif
 166