1 | /** |
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2 | * @file |
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3 | * |
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4 | * @ingroup RTEMSBSPsPowerPCShared |
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5 | * |
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6 | * @brief Source file for a clock driver. |
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7 | */ |
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8 | |
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9 | /* |
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10 | * Copyright (c) 2008-2015 embedded brains GmbH. All rights reserved. |
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11 | * |
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12 | * embedded brains GmbH |
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13 | * Obere Lagerstr. 30 |
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14 | * 82178 Puchheim |
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15 | * Germany |
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16 | * <rtems@embedded-brains.de> |
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17 | * |
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18 | * The license and distribution terms for this file may be |
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19 | * found in the file LICENSE in this distribution or at |
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20 | * http://www.rtems.org/license/LICENSE. |
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21 | */ |
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22 | |
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23 | #include <rtems.h> |
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24 | #include <rtems/clockdrv.h> |
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25 | #include <rtems/timecounter.h> |
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26 | |
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27 | #include <libcpu/powerpc-utility.h> |
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28 | #include <bsp/vectors.h> |
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29 | |
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30 | #define RTEMS_STATUS_CHECKS_USE_PRINTK |
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31 | |
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32 | #include <rtems/status-checks.h> |
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33 | |
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34 | /* |
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35 | * This variable must be defined in the BSP and valid before clock driver |
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36 | * initialization. |
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37 | */ |
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38 | extern uint32_t bsp_time_base_frequency; |
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39 | |
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40 | #define PPC405_PIT 0x3db |
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41 | |
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42 | #define PPC_CLOCK_DECREMENTER_MAX UINT32_MAX |
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43 | |
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44 | volatile uint32_t Clock_driver_ticks = 0; |
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45 | |
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46 | static uint32_t ppc_clock_decrementer_value = PPC_CLOCK_DECREMENTER_MAX; |
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47 | |
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48 | static uint32_t ppc_clock_next_time_base; |
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49 | |
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50 | static struct timecounter ppc_tc; |
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51 | |
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52 | static uint32_t ppc_get_timecount(struct timecounter *tc) |
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53 | { |
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54 | return ppc_time_base(); |
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55 | } |
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56 | |
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57 | static void ppc_clock_no_tick(void) |
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58 | { |
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59 | /* Do nothing */ |
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60 | } |
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61 | |
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62 | static void (*ppc_clock_tick)(void) = ppc_clock_no_tick; |
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63 | |
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64 | static int ppc_clock_exception_handler( |
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65 | BSP_Exception_frame *frame, |
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66 | unsigned number |
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67 | ) |
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68 | { |
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69 | uint32_t delta = ppc_clock_decrementer_value; |
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70 | uint32_t next = ppc_clock_next_time_base; |
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71 | uint32_t dec = 0; |
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72 | uint32_t now = 0; |
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73 | uint32_t msr = 0; |
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74 | |
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75 | do { |
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76 | /* Increment clock ticks */ |
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77 | Clock_driver_ticks += 1; |
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78 | |
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79 | /* Enable external exceptions */ |
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80 | msr = ppc_external_exceptions_enable(); |
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81 | |
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82 | /* Call clock ticker */ |
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83 | ppc_clock_tick(); |
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84 | |
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85 | /* Restore machine state */ |
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86 | ppc_external_exceptions_disable( msr); |
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87 | |
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88 | /* Next time base */ |
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89 | next += delta; |
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90 | |
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91 | /* Current time */ |
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92 | now = ppc_time_base(); |
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93 | |
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94 | /* New decrementer value */ |
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95 | dec = next - now; |
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96 | } while (dec > delta); |
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97 | |
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98 | /* Set decrementer */ |
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99 | ppc_set_decrementer_register( dec); |
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100 | |
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101 | /* Expected next time base */ |
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102 | ppc_clock_next_time_base = next; |
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103 | |
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104 | return 0; |
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105 | } |
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106 | |
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107 | static int ppc_clock_exception_handler_first( |
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108 | BSP_Exception_frame *frame, |
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109 | unsigned number |
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110 | ) |
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111 | { |
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112 | /* We have to clear the first pending decrementer exception this way */ |
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113 | |
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114 | if (ppc_decrementer_register() >= 0x80000000) { |
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115 | ppc_clock_exception_handler( frame, number); |
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116 | } |
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117 | |
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118 | ppc_exc_set_handler( ASM_DEC_VECTOR, ppc_clock_exception_handler); |
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119 | |
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120 | return 0; |
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121 | } |
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122 | |
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123 | static int ppc_clock_exception_handler_booke( |
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124 | BSP_Exception_frame *frame, |
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125 | unsigned number |
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126 | ) |
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127 | { |
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128 | uint32_t msr; |
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129 | |
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130 | /* Acknowledge decrementer request */ |
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131 | PPC_SET_SPECIAL_PURPOSE_REGISTER( BOOKE_TSR, BOOKE_TSR_DIS); |
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132 | |
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133 | /* Increment clock ticks */ |
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134 | Clock_driver_ticks += 1; |
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135 | |
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136 | /* Enable external exceptions */ |
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137 | msr = ppc_external_exceptions_enable(); |
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138 | |
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139 | /* Call clock ticker */ |
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140 | ppc_clock_tick(); |
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141 | |
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142 | /* Restore machine state */ |
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143 | ppc_external_exceptions_disable( msr); |
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144 | |
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145 | return 0; |
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146 | } |
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147 | |
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148 | static int ppc_clock_exception_handler_ppc405(BSP_Exception_frame *frame, unsigned number) |
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149 | { |
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150 | uint32_t msr; |
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151 | |
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152 | /* Acknowledge PIT request */ |
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153 | PPC_SET_SPECIAL_PURPOSE_REGISTER(PPC405_TSR, BOOKE_TSR_DIS); |
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154 | |
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155 | /* Increment clock ticks */ |
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156 | Clock_driver_ticks += 1; |
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157 | |
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158 | /* Enable external exceptions */ |
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159 | msr = ppc_external_exceptions_enable(); |
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160 | |
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161 | /* Call clock ticker */ |
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162 | ppc_clock_tick(); |
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163 | |
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164 | /* Restore machine state */ |
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165 | ppc_external_exceptions_disable(msr); |
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166 | |
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167 | return 0; |
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168 | } |
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169 | |
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170 | void Clock_exit(void) |
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171 | { |
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172 | /* Set the decrementer to the maximum value */ |
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173 | ppc_set_decrementer_register( PPC_CLOCK_DECREMENTER_MAX); |
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174 | |
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175 | /* Use default clock handler */ |
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176 | ppc_clock_tick = ppc_clock_no_tick; |
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177 | } |
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178 | |
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179 | rtems_device_driver Clock_initialize( |
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180 | rtems_device_major_number major, |
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181 | rtems_device_minor_number minor, |
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182 | void *arg |
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183 | ) |
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184 | { |
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185 | uint64_t frequency = bsp_time_base_frequency; |
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186 | uint64_t us_per_tick = rtems_configuration_get_microseconds_per_tick(); |
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187 | uint32_t interval = (uint32_t) ((frequency * us_per_tick) / 1000000); |
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188 | |
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189 | /* |
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190 | * Set default ticker. |
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191 | */ |
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192 | ppc_clock_tick = rtems_timecounter_tick; |
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193 | |
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194 | if (ppc_cpu_is_bookE() != PPC_BOOKE_405) { |
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195 | /* Decrementer value */ |
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196 | ppc_clock_decrementer_value = interval - 1; |
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197 | |
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198 | /* Check decrementer value */ |
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199 | if (ppc_clock_decrementer_value == 0) { |
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200 | ppc_clock_decrementer_value = PPC_CLOCK_DECREMENTER_MAX; |
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201 | RTEMS_SYSLOG_ERROR( "decrementer value would be zero, will be set to maximum value instead\n"); |
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202 | } |
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203 | if (ppc_cpu_is_bookE()) { |
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204 | /* Set decrementer auto-reload value */ |
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205 | PPC_SET_SPECIAL_PURPOSE_REGISTER( BOOKE_DECAR, ppc_clock_decrementer_value); |
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206 | |
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207 | /* Install exception handler */ |
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208 | ppc_exc_set_handler( ASM_BOOKE_DEC_VECTOR, ppc_clock_exception_handler_booke); |
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209 | |
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210 | /* Enable decrementer and auto-reload */ |
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211 | PPC_SET_SPECIAL_PURPOSE_REGISTER_BITS( BOOKE_TCR, BOOKE_TCR_DIE | BOOKE_TCR_ARE); |
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212 | } else { |
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213 | /* Here the decrementer value is actually the interval */ |
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214 | ++ppc_clock_decrementer_value; |
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215 | |
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216 | /* Initialize next time base */ |
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217 | ppc_clock_next_time_base = ppc_time_base() + ppc_clock_decrementer_value; |
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218 | |
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219 | /* Install exception handler */ |
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220 | ppc_exc_set_handler( ASM_DEC_VECTOR, ppc_clock_exception_handler_first); |
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221 | } |
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222 | |
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223 | /* Set the decrementer value */ |
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224 | ppc_set_decrementer_register( ppc_clock_decrementer_value); |
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225 | } else { |
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226 | /* PIT interval value */ |
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227 | ppc_clock_decrementer_value = interval; |
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228 | |
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229 | /* Install exception handler */ |
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230 | ppc_exc_set_handler(ASM_BOOKE_DEC_VECTOR, ppc_clock_exception_handler_ppc405); |
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231 | |
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232 | /* Enable PIT and auto-reload */ |
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233 | PPC_SET_SPECIAL_PURPOSE_REGISTER_BITS(PPC405_TCR, BOOKE_TCR_DIE | BOOKE_TCR_ARE); |
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234 | |
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235 | /* Set PIT auto-reload and initial value */ |
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236 | PPC_SET_SPECIAL_PURPOSE_REGISTER(PPC405_PIT, interval); |
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237 | } |
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238 | |
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239 | /* Install timecounter */ |
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240 | ppc_tc.tc_get_timecount = ppc_get_timecount; |
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241 | ppc_tc.tc_counter_mask = 0xffffffff; |
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242 | ppc_tc.tc_frequency = frequency; |
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243 | ppc_tc.tc_quality = RTEMS_TIMECOUNTER_QUALITY_CLOCK_DRIVER; |
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244 | rtems_timecounter_install(&ppc_tc); |
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245 | |
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246 | return RTEMS_SUCCESSFUL; |
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247 | } |
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