1 | /* clock.c |
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2 | * |
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3 | * This routine initializes the PIT on the MPC860. |
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4 | * The tick frequency is specified by the bsp. |
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5 | * |
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6 | * Author: Jay Monkman (jmonkman@frasca.com) |
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7 | * Copyright (C) 1998 by Frasca International, Inc. |
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8 | * |
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9 | * Derived from c/src/lib/libcpu/ppc/ppc403/clock/clock.c: |
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10 | * |
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11 | * Author: Andrew Bray <andy@i-cubed.co.uk> |
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12 | * |
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13 | * COPYRIGHT (c) 1995 by i-cubed ltd. |
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14 | * |
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15 | * To anyone who acknowledges that this file is provided "AS IS" |
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16 | * without any express or implied warranty: |
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17 | * permission to use, copy, modify, and distribute this file |
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18 | * for any purpose is hereby granted without fee, provided that |
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19 | * the above copyright notice and this notice appears in all |
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20 | * copies, and that the name of i-cubed limited not be used in |
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21 | * advertising or publicity pertaining to distribution of the |
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22 | * software without specific, written prior permission. |
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23 | * i-cubed limited makes no representations about the suitability |
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24 | * of this software for any purpose. |
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25 | * |
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26 | * Derived from c/src/lib/libcpu/hppa1_1/clock/clock.c: |
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27 | * |
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28 | * COPYRIGHT (c) 1989-1999. |
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29 | * On-Line Applications Research Corporation (OAR). |
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30 | * |
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31 | * The license and distribution terms for this file may be |
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32 | * found in the file LICENSE in this distribution or at |
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33 | * http://www.OARcorp.com/rtems/license.html. |
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34 | * |
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35 | * $Id$ |
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36 | */ |
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37 | |
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38 | #include <rtems.h> |
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39 | #include <clockdrv.h> |
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40 | #include <rtems/libio.h> |
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41 | |
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42 | #include <stdlib.h> /* for atexit() */ |
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43 | #include <mpc860.h> |
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44 | |
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45 | volatile rtems_unsigned32 Clock_driver_ticks; |
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46 | extern volatile m860_t m860; |
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47 | |
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48 | void Clock_exit( void ); |
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49 | |
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50 | /* |
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51 | * These are set by clock driver during its init |
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52 | */ |
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53 | |
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54 | rtems_device_major_number rtems_clock_major = ~0; |
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55 | rtems_device_minor_number rtems_clock_minor; |
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56 | |
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57 | /* |
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58 | * ISR Handler |
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59 | */ |
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60 | rtems_isr Clock_isr(rtems_vector_number vector) |
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61 | { |
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62 | m860.piscr |= M860_PISCR_PS; |
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63 | Clock_driver_ticks++; |
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64 | rtems_clock_tick(); |
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65 | } |
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66 | |
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67 | void Install_clock(rtems_isr_entry clock_isr) |
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68 | { |
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69 | rtems_isr_entry previous_isr; |
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70 | rtems_unsigned32 pit_value; |
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71 | |
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72 | Clock_driver_ticks = 0; |
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73 | |
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74 | pit_value = rtems_configuration_get_microseconds_per_tick() / |
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75 | rtems_cpu_configuration_get_clicks_per_usec(); |
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76 | if (pit_value == 0) { |
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77 | pit_value = 0xffff; |
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78 | } else { |
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79 | pit_value--; |
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80 | } |
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81 | |
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82 | if (pit_value > 0xffff) { /* pit is only 16 bits long */ |
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83 | rtems_fatal_error_occurred(-1); |
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84 | } |
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85 | |
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86 | /* |
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87 | * initialize the interval here |
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88 | * First tick is set to right amount of time in the future |
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89 | * Future ticks will be incremented over last value set |
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90 | * in order to provide consistent clicks in the face of |
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91 | * interrupt overhead |
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92 | */ |
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93 | |
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94 | rtems_interrupt_catch(clock_isr, PPC_IRQ_LVL0, &previous_isr); |
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95 | |
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96 | m860.sccr &= ~(1<<24); |
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97 | m860.pitc = pit_value; |
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98 | |
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99 | /* set PIT irq level, enable PIT, PIT interrupts */ |
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100 | /* and clear int. status */ |
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101 | m860.piscr = M860_PISCR_PIRQ(0) | |
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102 | M860_PISCR_PTE | M860_PISCR_PS | M860_PISCR_PIE; |
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103 | |
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104 | m860.simask |= M860_SIMASK_LVM0; |
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105 | atexit(Clock_exit); |
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106 | } |
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107 | |
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108 | void |
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109 | ReInstall_clock(rtems_isr_entry new_clock_isr) |
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110 | { |
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111 | rtems_isr_entry previous_isr; |
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112 | rtems_unsigned32 isrlevel = 0; |
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113 | |
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114 | rtems_interrupt_disable(isrlevel); |
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115 | |
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116 | rtems_interrupt_catch(new_clock_isr, PPC_IRQ_LVL0, &previous_isr); |
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117 | |
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118 | rtems_interrupt_enable(isrlevel); |
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119 | } |
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120 | |
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121 | |
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122 | /* |
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123 | * Called via atexit() |
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124 | * Remove the clock interrupt handler by setting handler to NULL |
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125 | */ |
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126 | void |
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127 | Clock_exit(void) |
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128 | { |
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129 | /* disable PIT and PIT interrupts */ |
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130 | m860.piscr &= ~(M860_PISCR_PTE | M860_PISCR_PIE); |
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131 | |
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132 | (void) set_vector(0, PPC_IRQ_LVL0, 1); |
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133 | } |
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134 | |
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135 | rtems_device_driver Clock_initialize( |
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136 | rtems_device_major_number major, |
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137 | rtems_device_minor_number minor, |
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138 | void *pargp |
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139 | ) |
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140 | { |
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141 | Install_clock( Clock_isr ); |
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142 | |
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143 | /* |
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144 | * make major/minor avail to others such as shared memory driver |
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145 | */ |
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146 | |
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147 | rtems_clock_major = major; |
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148 | rtems_clock_minor = minor; |
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149 | |
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150 | return RTEMS_SUCCESSFUL; |
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151 | } |
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152 | |
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153 | rtems_device_driver Clock_control( |
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154 | rtems_device_major_number major, |
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155 | rtems_device_minor_number minor, |
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156 | void *pargp |
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157 | ) |
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158 | { |
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159 | rtems_libio_ioctl_args_t *args = pargp; |
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160 | |
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161 | if (args == 0) |
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162 | goto done; |
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163 | |
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164 | /* |
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165 | * This is hokey, but until we get a defined interface |
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166 | * to do this, it will just be this simple... |
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167 | */ |
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168 | |
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169 | if (args->command == rtems_build_name('I', 'S', 'R', ' ')) { |
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170 | Clock_isr(PPC_IRQ_LVL0); |
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171 | } |
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172 | else if (args->command == rtems_build_name('N', 'E', 'W', ' ')) { |
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173 | ReInstall_clock(args->buffer); |
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174 | } |
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175 | |
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176 | done: |
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177 | return RTEMS_SUCCESSFUL; |
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178 | } |
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179 | |
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