arch/hexagon/include/asm/spinlock.h

   1 /*
   2  * Spinlock support for the Hexagon architecture
   3  *
   4  * Copyright (c) 2010-2011, 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_SPINLOCK_H
  23 #define _ASM_SPINLOCK_H
  24
  25 #include <asm/irqflags.h>
  26 #include <asm/barrier.h>
  27 #include <asm/processor.h>
  28
  29 /*
  30  * This file is pulled in for SMP builds.
  31  * Really need to check all the barrier stuff for "true" SMP
  32  */
  33
  34 /*
  35  * Read locks:
  36  * - load the lock value
  37  * - increment it
  38  * - if the lock value is still negative, go back and try again.
  39  * - unsuccessful store is unsuccessful.  Go back and try again.  Loser.
  40  * - successful store new lock value if positive -> lock acquired
  41  */
  42 static inline void arch_read_lock(arch_rwlock_t *lock)
  43 {
  44         __asm__ __volatile__(
  45                 "1:     R6 = memw_locked(%0);\n"
  46                 "       { P3 = cmp.ge(R6,#0); R6 = add(R6,#1);}\n"
  47                 "       { if !P3 jump 1b; }\n"
  48                 "       memw_locked(%0,P3) = R6;\n"
  49                 "       { if !P3 jump 1b; }\n"
  50                 :
  51                 : "r" (&lock->lock)
  52                 : "memory", "r6", "p3"
  53         );
  54
  55 }
  56
  57 static inline void arch_read_unlock(arch_rwlock_t *lock)
  58 {
  59         __asm__ __volatile__(
  60                 "1:     R6 = memw_locked(%0);\n"
  61                 "       R6 = add(R6,#-1);\n"
  62                 "       memw_locked(%0,P3) = R6\n"
  63                 "       if !P3 jump 1b;\n"
  64                 :
  65                 : "r" (&lock->lock)
  66                 : "memory", "r6", "p3"
  67         );
  68
  69 }
  70
  71 /*  I think this returns 0 on fail, 1 on success.  */
  72 static inline int arch_read_trylock(arch_rwlock_t *lock)
  73 {
  74         int temp;
  75         __asm__ __volatile__(
  76                 "       R6 = memw_locked(%1);\n"
  77                 "       { %0 = #0; P3 = cmp.ge(R6,#0); R6 = add(R6,#1);}\n"
  78                 "       { if !P3 jump 1f; }\n"
  79                 "       memw_locked(%1,P3) = R6;\n"
  80                 "       { %0 = P3 }\n"
  81                 "1:\n"
  82                 : "=&r" (temp)
  83                 : "r" (&lock->lock)
  84                 : "memory", "r6", "p3"
  85         );
  86         return temp;
  87 }
  88
  89 static inline int arch_read_can_lock(arch_rwlock_t *rwlock)
  90 {
  91         return rwlock->lock == 0;
  92 }
  93
  94 static inline int arch_write_can_lock(arch_rwlock_t *rwlock)
  95 {
  96         return rwlock->lock == 0;
  97 }
  98
  99 /*  Stuffs a -1 in the lock value?  */
 100 static inline void arch_write_lock(arch_rwlock_t *lock)
 101 {
 102         __asm__ __volatile__(
 103                 "1:     R6 = memw_locked(%0)\n"
 104                 "       { P3 = cmp.eq(R6,#0);  R6 = #-1;}\n"
 105                 "       { if !P3 jump 1b; }\n"
 106                 "       memw_locked(%0,P3) = R6;\n"
 107                 "       { if !P3 jump 1b; }\n"
 108                 :
 109                 : "r" (&lock->lock)
 110                 : "memory", "r6", "p3"
 111         );
 112 }
 113
 114
 115 static inline int arch_write_trylock(arch_rwlock_t *lock)
 116 {
 117         int temp;
 118         __asm__ __volatile__(
 119                 "       R6 = memw_locked(%1)\n"
 120                 "       { %0 = #0; P3 = cmp.eq(R6,#0);  R6 = #-1;}\n"
 121                 "       { if !P3 jump 1f; }\n"
 122                 "       memw_locked(%1,P3) = R6;\n"
 123                 "       %0 = P3;\n"
 124                 "1:\n"
 125                 : "=&r" (temp)
 126                 : "r" (&lock->lock)
 127                 : "memory", "r6", "p3"
 128         );
 129         return temp;
 130
 131 }
 132
 133 static inline void arch_write_unlock(arch_rwlock_t *lock)
 134 {
 135         smp_mb();
 136         lock->lock = 0;
 137 }
 138
 139 static inline void arch_spin_lock(arch_spinlock_t *lock)
 140 {
 141         __asm__ __volatile__(
 142                 "1:     R6 = memw_locked(%0);\n"
 143                 "       P3 = cmp.eq(R6,#0);\n"
 144                 "       { if !P3 jump 1b; R6 = #1; }\n"
 145                 "       memw_locked(%0,P3) = R6;\n"
 146                 "       { if !P3 jump 1b; }\n"
 147                 :
 148                 : "r" (&lock->lock)
 149                 : "memory", "r6", "p3"
 150         );
 151
 152 }
 153
 154 static inline void arch_spin_unlock(arch_spinlock_t *lock)
 155 {
 156         smp_mb();
 157         lock->lock = 0;
 158 }
 159
 160 static inline unsigned int arch_spin_trylock(arch_spinlock_t *lock)
 161 {
 162         int temp;
 163         __asm__ __volatile__(
 164                 "       R6 = memw_locked(%1);\n"
 165                 "       P3 = cmp.eq(R6,#0);\n"
 166                 "       { if !P3 jump 1f; R6 = #1; %0 = #0; }\n"
 167                 "       memw_locked(%1,P3) = R6;\n"
 168                 "       %0 = P3;\n"
 169                 "1:\n"
 170                 : "=&r" (temp)
 171                 : "r" (&lock->lock)
 172                 : "memory", "r6", "p3"
 173         );
 174         return temp;
 175 }
 176
 177 /*
 178  * SMP spinlocks are intended to allow only a single CPU at the lock
 179  */
 180 #define arch_spin_lock_flags(lock, flags) arch_spin_lock(lock)
 181
 182 #define arch_spin_is_locked(x) ((x)->lock != 0)
 183
 184 #define arch_read_lock_flags(lock, flags) arch_read_lock(lock)
 185 #define arch_write_lock_flags(lock, flags) arch_write_lock(lock)
 186
 187 #endif