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  1. /*
  2.  * Copyright (C) 2001-2004 Jakub Jermar
  3.  * All rights reserved.
  4.  *
  5.  * Redistribution and use in source and binary forms, with or without
  6.  * modification, are permitted provided that the following conditions
  7.  * are met:
  8.  *
  9.  * - Redistributions of source code must retain the above copyright
  10.  *   notice, this list of conditions and the following disclaimer.
  11.  * - Redistributions in binary form must reproduce the above copyright
  12.  *   notice, this list of conditions and the following disclaimer in the
  13.  *   documentation and/or other materials provided with the distribution.
  14.  * - The name of the author may not be used to endorse or promote products
  15.  *   derived from this software without specific prior written permission.
  16.  *
  17.  * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
  18.  * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
  19.  * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
  20.  * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
  21.  * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
  22.  * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
  23.  * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
  24.  * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
  25.  * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
  26.  * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
  27.  */
  28.  
  29. #ifndef __SPINLOCK_H__
  30. #define __SPINLOCK_H__
  31.  
  32. #include <arch/types.h>
  33. #include <typedefs.h>
  34. #include <preemption.h>
  35. #include <atomic.h>
  36. #include <debug.h>
  37.  
  38. #ifdef CONFIG_SMP
  39. struct spinlock {
  40. #ifdef CONFIG_DEBUG_SPINLOCK
  41.     char *name;
  42. #endif
  43.     atomic_t val;
  44. };
  45.  
  46. /*
  47.  * SPINLOCK_DECLARE is to be used for dynamically allocated spinlocks,
  48.  * where the lock gets initialized in run time.
  49.  */
  50. #define SPINLOCK_DECLARE(slname)    spinlock_t slname
  51.  
  52. /*
  53.  * SPINLOCK_INITIALIZE is to be used for statically allocated spinlocks.
  54.  * It declares and initializes the lock.
  55.  */
  56. #ifdef CONFIG_DEBUG_SPINLOCK
  57. #define SPINLOCK_INITIALIZE(slname)     \
  58.     spinlock_t slname = {       \
  59.         .name = #slname,    \
  60.         .val = { 0 }        \
  61.     }
  62. #else
  63. #define SPINLOCK_INITIALIZE(slname)     \
  64.     spinlock_t slname = {       \
  65.         .val = { 0 }        \
  66.     }
  67. #endif
  68.  
  69. extern void spinlock_initialize(spinlock_t *sl, char *name);
  70. extern int spinlock_trylock(spinlock_t *sl);
  71. extern void spinlock_lock_debug(spinlock_t *sl);
  72.  
  73. #ifdef CONFIG_DEBUG_SPINLOCK
  74. #  define spinlock_lock(x) spinlock_lock_debug(x)
  75. #else
  76. #  define spinlock_lock(x) atomic_lock_arch(&(x)->val)
  77. #endif
  78.  
  79. /** Unlock spinlock
  80.  *
  81.  * Unlock spinlock.
  82.  *
  83.  * @param sl Pointer to spinlock_t structure.
  84.  */
  85. static inline void spinlock_unlock(spinlock_t *sl)
  86. {
  87.     ASSERT(atomic_get(&sl->val) != 0);
  88.  
  89.     /*
  90.      * Prevent critical section code from bleeding out this way down.
  91.      */
  92.     CS_LEAVE_BARRIER();
  93.    
  94.     atomic_set(&sl->val,0);
  95.     preemption_enable();
  96. }
  97.  
  98. #else
  99.  
  100. /* On UP systems, spinlocks are effectively left out. */
  101. #define SPINLOCK_DECLARE(name)
  102. #define SPINLOCK_INITIALIZE(name)
  103.  
  104. #define spinlock_initialize(x,name)
  105. #define spinlock_lock(x)        preemption_disable()
  106. #define spinlock_trylock(x)         (preemption_disable(), 1)
  107. #define spinlock_unlock(x)      preemption_enable()
  108.  
  109. #endif
  110.  
  111. #endif
  112.