1 | /** |
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2 | * @file rtems/score/corespinlock.h |
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3 | * |
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4 | * @brief Constants and Structures Associated with the Spinlock Handler |
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5 | * |
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6 | * This include file contains all the constants and structures associated |
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7 | * with the Spinlock Handler. |
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8 | */ |
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9 | |
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10 | /* |
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11 | * COPYRIGHT (c) 1989-2006. |
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12 | * On-Line Applications Research Corporation (OAR). |
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13 | * |
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14 | * The license and distribution terms for this file may be |
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15 | * found in the file LICENSE in this distribution or at |
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16 | * http://www.rtems.com/license/LICENSE. |
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17 | */ |
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18 | |
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19 | #ifndef _RTEMS_SCORE_CORESPINLOCK_H |
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20 | #define _RTEMS_SCORE_CORESPINLOCK_H |
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21 | |
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22 | /** |
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23 | * @defgroup ScoreSpinlock Spinlock Handler |
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24 | * |
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25 | * @ingroup Score |
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26 | * |
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27 | * This handler encapsulates functionality which provides the foundation |
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28 | * Spinlock services used in all of the APIs supported by RTEMS. |
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29 | */ |
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30 | /**@{*/ |
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31 | |
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32 | #ifdef __cplusplus |
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33 | extern "C" { |
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34 | #endif |
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35 | |
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36 | #include <rtems/score/thread.h> |
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37 | #include <rtems/score/priority.h> |
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38 | |
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39 | /** |
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40 | * Core Spinlock handler return statuses. |
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41 | */ |
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42 | typedef enum { |
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43 | /** This status indicates that the operation completed successfully. */ |
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44 | CORE_SPINLOCK_SUCCESSFUL, |
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45 | /** This status indicates that the current thread already holds the spinlock. |
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46 | * An attempt to relock it will result in deadlock. |
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47 | */ |
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48 | CORE_SPINLOCK_HOLDER_RELOCKING, |
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49 | /** This status indicates that the current thread is attempting to unlock a |
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50 | * spinlock that is held by another thread. |
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51 | */ |
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52 | CORE_SPINLOCK_NOT_HOLDER, |
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53 | /** This status indicates that a thread reached the limit of time it |
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54 | * was willing to wait on the spin lock. |
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55 | */ |
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56 | CORE_SPINLOCK_TIMEOUT, |
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57 | /** This status indicates that a thread is currently waiting for this |
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58 | * spin lock. |
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59 | */ |
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60 | CORE_SPINLOCK_IS_BUSY, |
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61 | /** This status indicates that the spinlock is currently locked and thus |
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62 | * unavailable. |
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63 | */ |
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64 | CORE_SPINLOCK_UNAVAILABLE, |
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65 | /** This status indicates that the spinlock is not currently locked and thus |
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66 | * should not be released. |
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67 | */ |
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68 | CORE_SPINLOCK_NOT_LOCKED |
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69 | } CORE_spinlock_Status; |
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70 | |
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71 | /** This is a shorthand for the last status code. */ |
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72 | #define CORE_SPINLOCK_STATUS_LAST CORE_SPINLOCK_NOT_LOCKED |
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73 | |
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74 | /** This indicates the lock is available. */ |
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75 | #define CORE_SPINLOCK_UNLOCKED 0 |
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76 | |
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77 | /** This indicates the lock is unavailable. */ |
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78 | #define CORE_SPINLOCK_LOCKED 1 |
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79 | |
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80 | /** |
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81 | * The following defines the control block used to manage the |
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82 | * attributes of each spinlock. |
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83 | */ |
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84 | typedef struct { |
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85 | /** This element indicates XXX |
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86 | */ |
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87 | uint32_t XXX; |
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88 | } CORE_spinlock_Attributes; |
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89 | |
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90 | /** |
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91 | * The following defines the control block used to manage each |
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92 | * spinlock. |
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93 | */ |
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94 | typedef struct { |
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95 | /** XXX may not be needed */ |
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96 | CORE_spinlock_Attributes Attributes; |
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97 | |
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98 | /** This field is the lock. |
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99 | */ |
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100 | volatile uint32_t lock; |
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101 | |
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102 | /** This field is a count of the current number of threads using |
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103 | * this spinlock. It includes the thread holding the lock as well |
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104 | * as those waiting. |
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105 | */ |
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106 | volatile uint32_t users; |
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107 | |
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108 | /** This field is the Id of the thread holding the lock. It may or may |
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109 | * not be the thread which acquired it. |
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110 | */ |
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111 | volatile Objects_Id holder; |
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112 | } CORE_spinlock_Control; |
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113 | |
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114 | /** |
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115 | * @brief Initialize the spinlock. |
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116 | * |
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117 | * This routine initializes the spinlock based on the parameters passed. |
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118 | * |
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119 | * @param[in] the_spinlock is the spinlock control block to initialize |
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120 | * @param[in] the_spinlock_attributes define the behavior of this instance |
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121 | */ |
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122 | void _CORE_spinlock_Initialize( |
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123 | CORE_spinlock_Control *the_spinlock, |
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124 | CORE_spinlock_Attributes *the_spinlock_attributes |
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125 | ); |
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126 | |
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127 | /** |
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128 | * @brief Wait for spinlock. |
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129 | * |
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130 | * This routine wait for the spinlock to be released. If the spinlock |
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131 | * is set to automatic and this is the appropriate thread, then it returns |
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132 | * immediately. Otherwise, the calling thread is blocked until the spinlock |
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133 | * is released. |
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134 | * |
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135 | * @param[in] the_spinlock is the spinlock to wait for |
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136 | * @param[in] wait is true if willing to wait |
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137 | * @param[in] timeout is the maximum number of ticks to spin (0 is forever) |
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138 | * |
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139 | * @retval A status is returned which indicates the success or failure of |
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140 | * this operation. |
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141 | */ |
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142 | CORE_spinlock_Status _CORE_spinlock_Wait( |
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143 | CORE_spinlock_Control *the_spinlock, |
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144 | bool wait, |
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145 | Watchdog_Interval timeout |
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146 | ); |
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147 | |
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148 | /** |
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149 | * @brief Manually release the spinlock. |
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150 | * |
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151 | * This routine manually releases the spinlock. All of the threads waiting |
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152 | * for the spinlock will be readied. |
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153 | * |
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154 | * @param[in] the_spinlock is the spinlock to surrender |
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155 | */ |
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156 | CORE_spinlock_Status _CORE_spinlock_Release( |
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157 | CORE_spinlock_Control *the_spinlock |
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158 | ); |
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159 | |
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160 | #ifndef __RTEMS_APPLICATION__ |
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161 | #include <rtems/score/corespinlock.inl> |
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162 | #endif |
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163 | |
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164 | #ifdef __cplusplus |
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165 | } |
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166 | #endif |
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167 | |
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168 | /**@}*/ |
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169 | |
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170 | #endif |
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171 | /* end of include file */ |
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