1 | /* |
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2 | * Clock Tick Device Driver |
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3 | * |
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4 | * This routine utilizes the Decrementer Register common to the PPC family. |
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5 | * |
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6 | * The tick frequency is directly programmed to the configured number of |
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7 | * microseconds per tick. |
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8 | * |
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9 | * COPYRIGHT (c) 1989-1999. |
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10 | * On-Line Applications Research Corporation (OAR). |
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11 | * |
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12 | * The license and distribution terms for this file may be |
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13 | * found in found in the file LICENSE in this distribution or at |
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14 | * http://www.OARcorp.com/rtems/license.html. |
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15 | * |
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16 | * $Id$ |
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17 | */ |
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18 | |
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19 | #include <stdlib.h> |
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20 | |
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21 | #include <bsp.h> |
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22 | #include <rtems/libio.h> |
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23 | |
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24 | /* |
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25 | * The Real Time Clock Counter Timer uses this trap type. |
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26 | */ |
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27 | |
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28 | #define CLOCK_VECTOR PPC_IRQ_DECREMENTER |
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29 | |
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30 | /* |
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31 | * Clock ticks since initialization |
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32 | */ |
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33 | |
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34 | volatile rtems_unsigned32 Clock_driver_ticks; |
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35 | |
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36 | /* |
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37 | * This is the value programmed into the count down timer. It |
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38 | * is artificially lowered when PSIM_FAST_IDLE is defined to |
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39 | * cut down how long we spend in the idle task while executing on |
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40 | * the simulator. |
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41 | */ |
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42 | |
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43 | extern rtems_unsigned32 CPU_PPC_CLICKS_PER_TICK; |
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44 | |
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45 | rtems_isr_entry Old_ticker; |
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46 | |
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47 | void Clock_exit( void ); |
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48 | |
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49 | /* |
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50 | * These are set by clock driver during its init |
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51 | */ |
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52 | |
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53 | rtems_device_major_number rtems_clock_major = ~0; |
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54 | rtems_device_minor_number rtems_clock_minor; |
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55 | |
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56 | /* |
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57 | * Clock_isr |
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58 | * |
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59 | * This is the clock tick interrupt handler. |
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60 | * |
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61 | * Input parameters: |
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62 | * vector - vector number |
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63 | * |
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64 | * Output parameters: NONE |
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65 | * |
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66 | * Return values: NONE |
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67 | * |
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68 | */ |
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69 | |
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70 | #define PPC_Set_decrementer( _clicks ) \ |
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71 | do { \ |
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72 | asm volatile( "mtdec %0" : "=r" ((_clicks)) : "r" ((_clicks)) ); \ |
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73 | } while (0) |
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74 | |
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75 | rtems_isr Clock_isr( |
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76 | rtems_vector_number vector |
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77 | ) |
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78 | { |
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79 | /* |
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80 | * Whether or not we we are in "fast idle" mode, the value for clicks |
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81 | * per tick must be programmed. If we are using "fast idle" mode for |
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82 | * a simulator, then the clicks per tick value is lowered to decrease |
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83 | * the amount of time spent executing the idle task while using the |
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84 | * an instruction simulator like psim. |
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85 | */ |
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86 | |
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87 | |
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88 | PPC_Set_decrementer( CPU_PPC_CLICKS_PER_TICK ); |
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89 | |
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90 | /* |
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91 | * The driver has seen another tick. |
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92 | */ |
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93 | |
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94 | Clock_driver_ticks += 1; |
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95 | |
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96 | /* |
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97 | * Real Time Clock counter/timer is set to automatically reload. |
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98 | */ |
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99 | |
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100 | rtems_clock_tick(); |
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101 | } |
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102 | |
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103 | /* |
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104 | * Install_clock |
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105 | * |
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106 | * This routine actually performs the hardware initialization for the clock. |
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107 | * |
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108 | * Input parameters: |
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109 | * clock_isr - clock interrupt service routine entry point |
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110 | * |
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111 | * Output parameters: NONE |
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112 | * |
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113 | * Return values: NONE |
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114 | * |
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115 | */ |
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116 | |
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117 | extern int CLOCK_SPEED; |
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118 | |
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119 | void Install_clock( |
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120 | rtems_isr_entry clock_isr |
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121 | ) |
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122 | { |
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123 | Clock_driver_ticks = 0; |
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124 | |
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125 | if ( BSP_Configuration.ticks_per_timeslice ) { |
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126 | Old_ticker = (rtems_isr_entry) set_vector( clock_isr, CLOCK_VECTOR, 1 ); |
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127 | |
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128 | PPC_Set_decrementer( CPU_PPC_CLICKS_PER_TICK ); |
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129 | |
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130 | atexit( Clock_exit ); |
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131 | } |
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132 | |
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133 | } |
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134 | |
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135 | /* |
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136 | * Clock_exit |
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137 | * |
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138 | * This routine allows the clock driver to exit by masking the interrupt and |
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139 | * disabling the clock's counter. |
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140 | * |
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141 | * Input parameters: NONE |
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142 | * |
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143 | * Output parameters: NONE |
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144 | * |
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145 | * Return values: NONE |
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146 | * |
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147 | */ |
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148 | |
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149 | void Clock_exit( void ) |
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150 | { |
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151 | if ( BSP_Configuration.ticks_per_timeslice ) { |
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152 | |
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153 | /* nothing to do */; |
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154 | |
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155 | /* do not restore old vector */ |
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156 | } |
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157 | } |
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158 | |
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159 | /* |
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160 | * Clock_initialize |
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161 | * |
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162 | * This routine initializes the clock driver. |
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163 | * |
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164 | * Input parameters: |
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165 | * major - clock device major number |
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166 | * minor - clock device minor number |
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167 | * parg - pointer to optional device driver arguments |
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168 | * |
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169 | * Output parameters: NONE |
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170 | * |
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171 | * Return values: |
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172 | * rtems_device_driver status code |
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173 | */ |
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174 | |
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175 | rtems_device_driver Clock_initialize( |
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176 | rtems_device_major_number major, |
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177 | rtems_device_minor_number minor, |
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178 | void *pargp |
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179 | ) |
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180 | { |
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181 | Install_clock( Clock_isr ); |
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182 | |
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183 | /* |
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184 | * make major/minor avail to others such as shared memory driver |
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185 | */ |
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186 | |
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187 | rtems_clock_major = major; |
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188 | rtems_clock_minor = minor; |
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189 | |
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190 | return RTEMS_SUCCESSFUL; |
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191 | } |
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192 | |
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193 | /* |
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194 | * Clock_control |
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195 | * |
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196 | * This routine is the clock device driver control entry point. |
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197 | * |
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198 | * Input parameters: |
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199 | * major - clock device major number |
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200 | * minor - clock device minor number |
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201 | * parg - pointer to optional device driver arguments |
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202 | * |
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203 | * Output parameters: NONE |
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204 | * |
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205 | * Return values: |
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206 | * rtems_device_driver status code |
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207 | */ |
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208 | |
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209 | rtems_device_driver Clock_control( |
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210 | rtems_device_major_number major, |
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211 | rtems_device_minor_number minor, |
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212 | void *pargp |
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213 | ) |
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214 | { |
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215 | rtems_unsigned32 isrlevel; |
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216 | rtems_libio_ioctl_args_t *args = pargp; |
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217 | |
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218 | if (args == 0) |
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219 | goto done; |
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220 | |
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221 | /* |
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222 | * This is hokey, but until we get a defined interface |
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223 | * to do this, it will just be this simple... |
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224 | */ |
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225 | |
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226 | if (args->command == rtems_build_name('I', 'S', 'R', ' ')) |
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227 | { |
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228 | Clock_isr(CLOCK_VECTOR); |
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229 | } |
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230 | else if (args->command == rtems_build_name('N', 'E', 'W', ' ')) |
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231 | { |
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232 | rtems_interrupt_disable( isrlevel ); |
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233 | (void) set_vector( args->buffer, CLOCK_VECTOR, 1 ); |
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234 | rtems_interrupt_enable( isrlevel ); |
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235 | } |
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236 | |
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237 | done: |
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238 | return RTEMS_SUCCESSFUL; |
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239 | } |
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