1 | /* |
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2 | * This routine initializes the MC68360 Periodic Interval Timer |
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3 | * |
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4 | * The PIT has rather poor resolution, but it is easy to set up |
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5 | * and requires no housekeeping once it is going. |
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6 | * |
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7 | * Based on the `gen68302' board support package, and covered by the |
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8 | * original distribution terms. |
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9 | * |
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10 | * W. Eric Norum |
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11 | * Saskatchewan Accelerator Laboratory |
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12 | * University of Saskatchewan |
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13 | * Saskatoon, Saskatchewan, CANADA |
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14 | * eric@skatter.usask.ca |
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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 | /* |
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20 | * Input parameters: NONE |
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21 | * |
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22 | * Output parameters: NONE |
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23 | * |
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24 | * COPYRIGHT (c) 1989, 1990, 1991, 1992, 1993, 1994. |
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25 | * On-Line Applications Research Corporation (OAR). |
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26 | * All rights assigned to U.S. Government, 1994. |
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27 | * |
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28 | * This material may be reproduced by or for the U.S. Government pursuant |
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29 | * to the copyright license under the clause at DFARS 252.227-7013. This |
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30 | * notice must appear in all copies of this file and its derivatives. |
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31 | */ |
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32 | |
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33 | #include <stdlib.h> /* for atexit() */ |
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34 | #include <bsp.h> |
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35 | #include <rtems/libio.h> |
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36 | #include "m68360.h" |
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37 | |
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38 | #define CLOCK_VECTOR 120 |
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39 | #define CLOCK_IRQ_LEVEL 6 |
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40 | |
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41 | /* |
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42 | * Clock_driver_ticks is a monotonically increasing counter of the |
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43 | * number of clock ticks since the driver was initialized. |
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44 | */ |
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45 | volatile rtems_unsigned32 Clock_driver_ticks; |
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46 | |
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47 | /* |
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48 | * These are set by clock driver during its init |
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49 | */ |
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50 | |
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51 | rtems_device_major_number rtems_clock_major = ~0; |
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52 | rtems_device_minor_number rtems_clock_minor; |
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53 | |
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54 | /* |
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55 | * Periodic interval timer interrupt handler |
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56 | */ |
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57 | rtems_isr |
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58 | Clock_isr (rtems_vector_number vector) |
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59 | { |
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60 | Clock_driver_ticks++; |
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61 | rtems_clock_tick(); |
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62 | } |
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63 | |
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64 | void |
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65 | Clock_exit (void) |
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66 | { |
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67 | if (BSP_Configuration.ticks_per_timeslice ) { |
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68 | /* |
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69 | * Turn off periodic interval timer |
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70 | */ |
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71 | m360.pitr &= ~0xFF; |
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72 | } |
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73 | } |
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74 | |
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75 | static void |
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76 | Install_clock (rtems_isr_entry clock_isr) |
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77 | { |
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78 | Clock_driver_ticks = 0; |
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79 | if ( BSP_Configuration.ticks_per_timeslice ) { |
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80 | int pitr; |
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81 | |
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82 | /* |
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83 | * Choose periodic interval timer register value |
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84 | * For a 25 MHz external clock the basic clock rate is |
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85 | * 40 nsec * 128 * 4 = 20.48 usec/tick |
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86 | */ |
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87 | pitr = ((BSP_Configuration.microseconds_per_tick * 100) + 1023) / 2048; |
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88 | if (pitr >= 256) { |
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89 | pitr = (pitr + 255) / 512; |
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90 | if (pitr >= 256) |
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91 | pitr = 255; |
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92 | else if (pitr == 0) |
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93 | pitr = 1; |
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94 | pitr |= 0x100; |
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95 | } |
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96 | else if (pitr == 0) { |
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97 | pitr = 1; |
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98 | } |
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99 | m360.pitr &= ~0x1FF; |
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100 | m360.picr = (CLOCK_IRQ_LEVEL << 8) | CLOCK_VECTOR; |
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101 | set_vector (clock_isr, CLOCK_VECTOR, 1); |
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102 | m360.pitr |= pitr; |
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103 | atexit (Clock_exit); |
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104 | } |
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105 | } |
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106 | |
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107 | rtems_device_driver |
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108 | Clock_initialize( |
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109 | rtems_device_major_number major, |
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110 | rtems_device_minor_number minor, |
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111 | void *pargp |
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112 | ) |
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113 | { |
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114 | Install_clock (Clock_isr); |
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115 | |
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116 | /* |
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117 | * make major/minor avail to others such as shared memory driver |
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118 | */ |
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119 | rtems_clock_major = major; |
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120 | rtems_clock_minor = minor; |
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121 | |
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122 | return RTEMS_SUCCESSFUL; |
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123 | } |
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124 | |
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125 | rtems_device_driver Clock_control( |
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126 | rtems_device_major_number major, |
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127 | rtems_device_minor_number minor, |
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128 | void *pargp |
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129 | ) |
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130 | { |
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131 | rtems_unsigned32 isrlevel; |
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132 | rtems_libio_ioctl_args_t *args = pargp; |
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133 | |
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134 | if (args) { |
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135 | /* |
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136 | * This is hokey, but until we get a defined interface |
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137 | * to do this, it will just be this simple... |
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138 | */ |
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139 | if (args->command == rtems_build_name('I', 'S', 'R', ' ')) { |
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140 | Clock_isr( CLOCK_VECTOR); |
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141 | } |
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142 | else if (args->command == rtems_build_name('N', 'E', 'W', ' ')) { |
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143 | rtems_interrupt_disable( isrlevel ); |
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144 | (void) set_vector( args->buffer, CLOCK_VECTOR, 1 ); |
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145 | rtems_interrupt_enable( isrlevel ); |
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146 | } |
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147 | } |
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148 | return RTEMS_SUCCESSFUL; |
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149 | } |
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