1 | /* |
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2 | * Copyright (c) 2014 embedded brains GmbH. All rights reserved. |
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3 | * |
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4 | * embedded brains GmbH |
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5 | * Dornierstr. 4 |
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6 | * 82178 Puchheim |
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7 | * Germany |
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8 | * <rtems@embedded-brains.de> |
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9 | * |
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10 | * The license and distribution terms for this file may be |
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11 | * found in the file LICENSE in this distribution or at |
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12 | * http://www.rtems.org/license/LICENSE. |
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13 | */ |
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14 | |
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15 | #ifndef _RTEMS_SCORE_MRSP_H |
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16 | #define _RTEMS_SCORE_MRSP_H |
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17 | |
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18 | #include <rtems/score/cpuopts.h> |
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19 | |
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20 | #if defined(RTEMS_SMP) |
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21 | |
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22 | #include <rtems/score/chain.h> |
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23 | #include <rtems/score/scheduler.h> |
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24 | #include <rtems/score/thread.h> |
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25 | |
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26 | #ifdef __cplusplus |
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27 | extern "C" { |
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28 | #endif /* __cplusplus */ |
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29 | |
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30 | /** |
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31 | * @defgroup ScoreMRSP Multiprocessor Resource Sharing Protocol Handler |
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32 | * |
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33 | * @ingroup Score |
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34 | * |
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35 | * @brief Multiprocessor Resource Sharing Protocol (MrsP). |
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36 | * |
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37 | * The Multiprocessor Resource Sharing Protocol (MrsP) is defined in A. Burns |
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38 | * and A.J. Wellings, A Schedulability Compatible Multiprocessor Resource |
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39 | * Sharing Protocol - MrsP, Proceedings of the 25th Euromicro Conference on |
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40 | * Real-Time Systems (ECRTS 2013), July 2013. It is a generalization of the |
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41 | * Priority Ceiling Protocol to SMP systems. Each MrsP semaphore uses a |
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42 | * ceiling priority per scheduler instance. A task obtaining or owning a MrsP |
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43 | * semaphore will execute with the ceiling priority for its scheduler instance |
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44 | * as specified by the MrsP semaphore object. Tasks waiting to get ownership |
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45 | * of a MrsP semaphore will not relinquish the processor voluntarily. In case |
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46 | * the owner of a MrsP semaphore gets preempted it can ask all tasks waiting |
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47 | * for this semaphore to help out and temporarily borrow the right to execute |
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48 | * on one of their assigned processors. |
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49 | * |
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50 | * @{ |
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51 | */ |
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52 | |
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53 | /** |
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54 | * @brief MrsP status code. |
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55 | * |
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56 | * The values are chosen to directly map to RTEMS status codes. In case this |
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57 | * implementation is used for other APIs, then for example the errno values can |
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58 | * be added with a bit shift. |
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59 | */ |
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60 | typedef enum { |
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61 | MRSP_SUCCESSFUL = 0, |
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62 | MRSP_TIMEOUT = 6, |
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63 | MRSP_INVALID_NUMBER = 10, |
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64 | MRSP_RESOUCE_IN_USE = 12, |
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65 | MRSP_UNSATISFIED = 13, |
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66 | MRSP_INCORRECT_STATE = 14, |
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67 | MRSP_INVALID_PRIORITY = 19, |
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68 | MRSP_NOT_OWNER_OF_RESOURCE = 23, |
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69 | MRSP_NO_MEMORY = 26, |
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70 | |
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71 | /** |
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72 | * @brief Internal state used for MRSP_Rival::status to indicate that this |
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73 | * rival waits for resource ownership. |
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74 | */ |
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75 | MRSP_WAIT_FOR_OWNERSHIP = 255 |
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76 | } MRSP_Status; |
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77 | |
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78 | /** |
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79 | * @brief MrsP rival. |
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80 | * |
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81 | * The rivals are used by threads waiting for resource ownership. They are |
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82 | * registered in the MRSP control block. |
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83 | */ |
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84 | typedef struct { |
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85 | /** |
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86 | * @brief The node for registration in the MRSP rival chain. |
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87 | * |
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88 | * The chain operations are protected by the Giant lock and disabled |
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89 | * interrupts. |
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90 | * |
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91 | * @see MRSP_Control::Rivals. |
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92 | */ |
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93 | Chain_Node Node; |
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94 | |
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95 | /** |
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96 | * @brief Identification of the rival thread. |
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97 | */ |
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98 | Thread_Control *thread; |
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99 | |
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100 | /** |
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101 | * @brief The initial priority of the thread at the begin of the resource |
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102 | * obtain sequence. |
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103 | * |
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104 | * Used to restore the priority after a release of this resource or timeout. |
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105 | */ |
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106 | Priority_Control initial_priority; |
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107 | |
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108 | /** |
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109 | * @brief The initial help state of the thread at the begin of the resource |
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110 | * obtain sequence. |
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111 | * |
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112 | * Used to restore this state after a timeout. |
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113 | */ |
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114 | Scheduler_Help_state initial_help_state; |
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115 | |
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116 | /** |
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117 | * @brief The rival status. |
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118 | * |
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119 | * Initially the status is set to MRSP_WAIT_FOR_OWNERSHIP. The rival will |
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120 | * busy wait until a status change happens. This can be MRSP_SUCCESSFUL or |
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121 | * MRSP_TIMEOUT. State changes are protected by the Giant lock and disabled |
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122 | * interrupts. |
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123 | */ |
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124 | volatile MRSP_Status status; |
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125 | } MRSP_Rival; |
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126 | |
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127 | /** |
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128 | * @brief MrsP control block. |
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129 | */ |
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130 | typedef struct { |
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131 | /** |
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132 | * @brief Basic resource control. |
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133 | */ |
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134 | Resource_Control Resource; |
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135 | |
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136 | /** |
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137 | * @brief A chain of MrsP rivals waiting for resource ownership. |
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138 | * |
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139 | * @see MRSP_Rival::Node. |
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140 | */ |
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141 | Chain_Control Rivals; |
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142 | |
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143 | /** |
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144 | * @brief The initial priority of the owner before it was elevated to the |
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145 | * ceiling priority. |
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146 | */ |
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147 | Priority_Control initial_priority_of_owner; |
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148 | |
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149 | /** |
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150 | * @brief One ceiling priority per scheduler instance. |
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151 | */ |
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152 | Priority_Control *ceiling_priorities; |
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153 | } MRSP_Control; |
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154 | |
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155 | /** @} */ |
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156 | |
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157 | #ifdef __cplusplus |
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158 | } |
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159 | #endif /* __cplusplus */ |
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160 | |
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161 | #endif /* RTEMS_SMP */ |
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162 | |
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163 | #endif /* _RTEMS_SCORE_MRSP_H */ |
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