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