1 | /* |
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2 | * Clock Tick Device Driver using Timer Library implemented |
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3 | * by the GRLIB GPTIMER / LEON2 Timer drivers. |
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4 | * |
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5 | * COPYRIGHT (c) 2010. |
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6 | * Cobham Gaisler AB. |
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7 | * |
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8 | * The license and distribution terms for this file may be |
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9 | * found in the file LICENSE in this distribution or at |
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10 | * http://www.rtems.org/license/LICENSE. |
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11 | * |
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12 | */ |
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13 | |
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14 | #include <rtems.h> |
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15 | #include <stdlib.h> |
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16 | #include <bsp.h> |
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17 | #include <bsp/tlib.h> |
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18 | |
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19 | #ifdef RTEMS_DRVMGR_STARTUP |
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20 | |
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21 | /* Undefine this to save space in standard LEON configurations, |
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22 | * it will assume that Prescaler is running at 1MHz. |
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23 | */ |
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24 | #undef CLOCK_DRIVER_DONT_ASSUME_PRESCALER_1MHZ |
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25 | |
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26 | /* Set the below defines from bsp.h if function needed. |
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27 | #undef CLOCK_DRIVER_ISRS_PER_TICK |
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28 | #undef CLOCK_DRIVER_USE_FAST_IDLE |
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29 | */ |
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30 | #define Clock_driver_support_at_tick() |
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31 | |
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32 | /* |
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33 | * Number of Clock ticks since initialization |
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34 | */ |
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35 | volatile uint32_t Clock_driver_ticks; |
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36 | |
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37 | /* |
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38 | * Timer Number in Timer Library. Defaults to the first Timer in |
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39 | * the System. |
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40 | */ |
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41 | int Clock_timer = 0; |
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42 | |
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43 | /* |
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44 | * Timer Handle in Timer Library |
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45 | */ |
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46 | void *Clock_handle = NULL; |
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47 | |
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48 | #ifdef CLOCK_DRIVER_DONT_ASSUME_PRESCALER_1MHZ |
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49 | unsigned int Clock_basefreq; |
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50 | #endif |
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51 | |
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52 | void Clock_exit(void); |
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53 | void Clock_isr(void *arg_unused); |
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54 | |
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55 | /* |
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56 | * Major and minor number. |
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57 | */ |
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58 | |
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59 | rtems_device_major_number rtems_clock_major = UINT32_MAX; |
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60 | rtems_device_minor_number rtems_clock_minor; |
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61 | |
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62 | /* |
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63 | * Clock_isr |
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64 | * |
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65 | * This is the clock tick interrupt handler. |
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66 | * |
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67 | * Input parameters: |
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68 | * vector - vector number |
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69 | * |
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70 | * Output parameters: NONE |
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71 | * |
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72 | * Return values: NONE |
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73 | * |
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74 | */ |
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75 | |
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76 | void Clock_isr(void *arg_unused) |
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77 | { |
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78 | /* |
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79 | * Support for shared interrupts. Ack IRQ at source, only handle |
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80 | * interrupts generated from the tick-timer. Clearing pending bit |
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81 | * is also needed for Clock_nanoseconds_since_last_tick() to work. |
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82 | */ |
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83 | if ( tlib_interrupt_pending(Clock_handle, 1) == 0 ) |
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84 | return; |
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85 | |
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86 | /* |
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87 | * Accurate count of ISRs |
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88 | */ |
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89 | |
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90 | Clock_driver_ticks += 1; |
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91 | |
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92 | #ifdef CLOCK_DRIVER_USE_FAST_IDLE |
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93 | do { |
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94 | rtems_clock_tick(); |
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95 | } while ( _Thread_Executing == _Thread_Idle && |
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96 | _Thread_Heir == _Thread_Executing); |
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97 | |
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98 | Clock_driver_support_at_tick(); |
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99 | return; |
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100 | |
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101 | #else |
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102 | |
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103 | /* |
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104 | * Add custom handling at every tick from bsp.h |
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105 | */ |
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106 | Clock_driver_support_at_tick(); |
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107 | |
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108 | #ifdef CLOCK_DRIVER_ISRS_PER_TICK |
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109 | /* |
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110 | * The driver is multiple ISRs per clock tick. |
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111 | */ |
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112 | |
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113 | if ( !Clock_driver_isrs ) { |
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114 | |
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115 | rtems_clock_tick(); |
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116 | |
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117 | Clock_driver_isrs = CLOCK_DRIVER_ISRS_PER_TICK; |
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118 | } |
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119 | Clock_driver_isrs--; |
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120 | #else |
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121 | |
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122 | /* |
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123 | * The driver is one ISR per clock tick. |
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124 | */ |
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125 | rtems_clock_tick(); |
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126 | #endif |
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127 | #endif |
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128 | } |
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129 | |
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130 | /* |
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131 | * Clock_exit |
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132 | * |
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133 | * This routine allows the clock driver to exit by masking the interrupt and |
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134 | * disabling the clock's counter. |
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135 | * |
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136 | * Input parameters: NONE |
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137 | * |
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138 | * Output parameters: NONE |
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139 | * |
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140 | * Return values: NONE |
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141 | * |
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142 | */ |
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143 | |
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144 | void Clock_exit( void ) |
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145 | { |
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146 | /* Stop all activity of the Timer, no more ISRs. |
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147 | * We could be using tlib_close(), however tlib_stop() is quicker |
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148 | * and independent of IRQ unregister code. |
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149 | */ |
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150 | if ( Clock_handle ) { |
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151 | tlib_stop(Clock_handle); |
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152 | Clock_handle = NULL; |
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153 | } |
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154 | } |
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155 | |
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156 | static uint32_t Clock_nanoseconds_since_last_tick(void) |
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157 | { |
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158 | uint32_t clicks; |
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159 | int ip; |
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160 | |
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161 | if ( !Clock_handle ) |
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162 | return 0; |
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163 | |
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164 | tlib_get_counter(Clock_handle, (unsigned int *)&clicks); |
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165 | /* protect against timer counter underflow/overflow */ |
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166 | ip = tlib_interrupt_pending(Clock_handle, 0); |
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167 | if (ip) |
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168 | tlib_get_counter(Clock_handle, (unsigned int *)&clicks); |
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169 | |
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170 | #ifdef CLOCK_DRIVER_DONT_ASSUME_PRESCALER_1MHZ |
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171 | { |
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172 | /* Down counter. Calc from BaseFreq. */ |
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173 | uint64_t tmp; |
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174 | if (ip) |
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175 | clicks += Clock_basefreq; |
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176 | tmp = ((uint64_t)clicks * 1000000000) / ((uint64_t)Clock_basefreq); |
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177 | return (uint32_t)tmp; |
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178 | } |
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179 | #else |
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180 | /* Down counter. Timer base frequency is initialized to 1 MHz */ |
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181 | return (uint32_t) |
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182 | ((rtems_configuration_get_microseconds_per_tick() << ip) - clicks) * 1000; |
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183 | #endif |
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184 | } |
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185 | |
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186 | /* |
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187 | * Clock_initialize |
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188 | * |
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189 | * This routine initializes the clock driver and starts the Clock. |
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190 | * |
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191 | * Input parameters: |
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192 | * major - clock device major number |
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193 | * minor - clock device minor number |
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194 | * parg - pointer to optional device driver arguments |
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195 | * |
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196 | * Output parameters: NONE |
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197 | * |
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198 | * Return values: |
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199 | * rtems_device_driver status code |
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200 | */ |
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201 | |
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202 | rtems_device_driver Clock_initialize( |
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203 | rtems_device_major_number major, |
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204 | rtems_device_minor_number minor, |
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205 | void *pargp |
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206 | ) |
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207 | { |
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208 | unsigned int tick_hz; |
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209 | |
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210 | /* |
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211 | * Take Timer that should be used as system timer. |
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212 | * |
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213 | */ |
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214 | Clock_handle = tlib_open(Clock_timer); |
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215 | if ( Clock_handle == NULL ) { |
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216 | /* System Clock Timer not found */ |
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217 | return RTEMS_NOT_DEFINED; |
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218 | } |
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219 | |
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220 | /* |
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221 | * Install Clock ISR before starting timer |
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222 | */ |
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223 | tlib_irq_register(Clock_handle, Clock_isr, NULL); |
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224 | |
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225 | /* Set Timer Frequency to tick at Configured value. The Timer |
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226 | * Frequency is set in multiples of the timer base frequency. |
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227 | * |
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228 | * In standard LEON3 designs the base frequency is is 1MHz, to |
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229 | * save instructions undefine CLOCK_DRIVER_DONT_ASSUME_PRESCALER_1MHZ |
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230 | * to avoid 64-bit calculation. |
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231 | */ |
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232 | #ifdef CLOCK_DRIVER_DONT_ASSUME_PRESCALER_1MHZ |
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233 | { |
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234 | uint64_t tmp; |
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235 | |
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236 | tlib_get_freq(Clock_handle, &Clock_basefreq, NULL); |
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237 | |
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238 | tmp = (uint64_t)Clock_basefreq; |
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239 | tmp = tmp * (uint64_t)rtems_configuration_get_microseconds_per_tick(); |
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240 | tick_hz = tmp / 1000000; |
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241 | } |
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242 | #else |
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243 | tick_hz = rtems_configuration_get_microseconds_per_tick(); |
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244 | #endif |
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245 | |
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246 | tlib_set_freq(Clock_handle, tick_hz); |
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247 | |
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248 | rtems_clock_set_nanoseconds_extension(Clock_nanoseconds_since_last_tick); |
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249 | |
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250 | /* |
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251 | * IRQ and Frequency is setup, now we start the Timer. IRQ is still |
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252 | * disabled globally during startup, so IRQ will hold for a while. |
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253 | */ |
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254 | tlib_start(Clock_handle, 0); |
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255 | |
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256 | /* |
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257 | * Register function called at system shutdown |
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258 | */ |
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259 | atexit( Clock_exit ); |
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260 | |
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261 | /* |
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262 | * make major/minor avail to others such as shared memory driver |
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263 | */ |
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264 | |
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265 | rtems_clock_major = major; |
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266 | rtems_clock_minor = minor; |
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267 | |
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268 | /* |
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269 | * If we are counting ISRs per tick, then initialize the counter. |
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270 | */ |
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271 | |
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272 | #ifdef CLOCK_DRIVER_ISRS_PER_TICK |
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273 | Clock_driver_isrs = CLOCK_DRIVER_ISRS_PER_TICK; |
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274 | #endif |
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275 | |
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276 | return RTEMS_SUCCESSFUL; |
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277 | } |
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278 | |
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279 | /*** Timer Driver Interface ***/ |
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280 | |
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281 | /* Set system clock timer instance */ |
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282 | void Clock_timer_register(int timer_number) |
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283 | { |
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284 | Clock_timer = timer_number; |
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285 | } |
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286 | |
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287 | #endif |
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