arch/hexagon/include/asm/atomic.h

   1 /*
   2  * Atomic operations for the Hexagon architecture
   3  *
   4  * Copyright (c) 2010-2013, The Linux Foundation. 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 #include <asm/barrier.h>
  28
  29 #define ATOMIC_INIT(i)          { (i) }
  30
  31 /*  Normal writes in our arch don't clear lock reservations  */
  32
  33 static inline void atomic_set(atomic_t *v, int new)
  34 {
  35         asm volatile(
  36                 "1:     r6 = memw_locked(%0);\n"
  37                 "       memw_locked(%0,p0) = %1;\n"
  38                 "       if (!P0) jump 1b;\n"
  39                 :
  40                 : "r" (&v->counter), "r" (new)
  41                 : "memory", "p0", "r6"
  42         );
  43 }
  44
  45 /**
  46  * atomic_read - reads a word, atomically
  47  * @v: pointer to atomic value
  48  *
  49  * Assumes all word reads on our architecture are atomic.
  50  */
  51 #define atomic_read(v)          READ_ONCE((v)->counter)
  52
  53 /**
  54  * atomic_xchg - atomic
  55  * @v: pointer to memory to change
  56  * @new: new value (technically passed in a register -- see xchg)
  57  */
  58 #define atomic_xchg(v, new)     (xchg(&((v)->counter), (new)))
  59
  60
  61 /**
  62  * atomic_cmpxchg - atomic compare-and-exchange values
  63  * @v: pointer to value to change
  64  * @old:  desired old value to match
  65  * @new:  new value to put in
  66  *
  67  * Parameters are then pointer, value-in-register, value-in-register,
  68  * and the output is the old value.
  69  *
  70  * Apparently this is complicated for archs that don't support
  71  * the memw_locked like we do (or it's broken or whatever).
  72  *
  73  * Kind of the lynchpin of the rest of the generically defined routines.
  74  * Remember V2 had that bug with dotnew predicate set by memw_locked.
  75  *
  76  * "old" is "expected" old val, __oldval is actual old value
  77  */
  78 static inline int atomic_cmpxchg(atomic_t *v, int old, int new)
  79 {
  80         int __oldval;
  81
  82         asm volatile(
  83                 "1:     %0 = memw_locked(%1);\n"
  84                 "       { P0 = cmp.eq(%0,%2);\n"
  85                 "         if (!P0.new) jump:nt 2f; }\n"
  86                 "       memw_locked(%1,P0) = %3;\n"
  87                 "       if (!P0) jump 1b;\n"
  88                 "2:\n"
  89                 : "=&r" (__oldval)
  90                 : "r" (&v->counter), "r" (old), "r" (new)
  91                 : "memory", "p0"
  92         );
  93
  94         return __oldval;
  95 }
  96
  97 #define ATOMIC_OP(op)                                                   \
  98 static inline void atomic_##op(int i, atomic_t *v)                      \
  99 {                                                                       \
 100         int output;                                                     \
 101                                                                         \
 102         __asm__ __volatile__ (                                          \
 103                 "1:     %0 = memw_locked(%1);\n"                        \
 104                 "       %0 = "#op "(%0,%2);\n"                          \
 105                 "       memw_locked(%1,P3)=%0;\n"                       \
 106                 "       if !P3 jump 1b;\n"                              \
 107                 : "=&r" (output)                                        \
 108                 : "r" (&v->counter), "r" (i)                            \
 109                 : "memory", "p3"                                        \
 110         );                                                              \
 111 }                                                                       \
 112
 113 #define ATOMIC_OP_RETURN(op)                                                    \
 114 static inline int atomic_##op##_return(int i, atomic_t *v)              \
 115 {                                                                       \
 116         int output;                                                     \
 117                                                                         \
 118         __asm__ __volatile__ (                                          \
 119                 "1:     %0 = memw_locked(%1);\n"                        \
 120                 "       %0 = "#op "(%0,%2);\n"                          \
 121                 "       memw_locked(%1,P3)=%0;\n"                       \
 122                 "       if !P3 jump 1b;\n"                              \
 123                 : "=&r" (output)                                        \
 124                 : "r" (&v->counter), "r" (i)                            \
 125                 : "memory", "p3"                                        \
 126         );                                                              \
 127         return output;                                                  \
 128 }
 129
 130 #define ATOMIC_OPS(op) ATOMIC_OP(op) ATOMIC_OP_RETURN(op)
 131
 132 ATOMIC_OPS(add)
 133 ATOMIC_OPS(sub)
 134
 135 ATOMIC_OP(and)
 136 ATOMIC_OP(or)
 137 ATOMIC_OP(xor)
 138
 139 #undef ATOMIC_OPS
 140 #undef ATOMIC_OP_RETURN
 141 #undef ATOMIC_OP
 142
 143 /**
 144  * __atomic_add_unless - add unless the number is a given value
 145  * @v: pointer to value
 146  * @a: amount to add
 147  * @u: unless value is equal to u
 148  *
 149  * Returns old value.
 150  *
 151  */
 152
 153 static inline int __atomic_add_unless(atomic_t *v, int a, int u)
 154 {
 155         int __oldval;
 156         register int tmp;
 157
 158         asm volatile(
 159                 "1:     %0 = memw_locked(%2);"
 160                 "       {"
 161                 "               p3 = cmp.eq(%0, %4);"
 162                 "               if (p3.new) jump:nt 2f;"
 163                 "               %1 = add(%0, %3);"
 164                 "       }"
 165                 "       memw_locked(%2, p3) = %1;"
 166                 "       {"
 167                 "               if !p3 jump 1b;"
 168                 "       }"
 169                 "2:"
 170                 : "=&r" (__oldval), "=&r" (tmp)
 171                 : "r" (v), "r" (a), "r" (u)
 172                 : "memory", "p3"
 173         );
 174         return __oldval;
 175 }
 176
 177 #define atomic_inc_not_zero(v) atomic_add_unless((v), 1, 0)
 178
 179 #define atomic_inc(v) atomic_add(1, (v))
 180 #define atomic_dec(v) atomic_sub(1, (v))
 181
 182 #define atomic_inc_and_test(v) (atomic_add_return(1, (v)) == 0)
 183 #define atomic_dec_and_test(v) (atomic_sub_return(1, (v)) == 0)
 184 #define atomic_sub_and_test(i, v) (atomic_sub_return(i, (v)) == 0)
 185 #define atomic_add_negative(i, v) (atomic_add_return(i, (v)) < 0)
 186
 187 #define atomic_inc_return(v) (atomic_add_return(1, v))
 188 #define atomic_dec_return(v) (atomic_sub_return(1, v))
 189
 190 #endif