1 | /* ckinit.c |
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2 | * |
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3 | * Implementation of the Clock_initialize() functions |
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4 | * prototyped in rtems/c/src/lib/include/clockdrv.h. |
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5 | * |
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6 | * This port does not allow the application to select which timer on the |
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7 | * MVME167 to use for the clock, nor does it allow the application to |
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8 | * configure the clock. The clock uses the VMEchip2 Tick Timer #2. This |
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9 | * timer is set up to raise a MC680x0 level-6 interrupt every 1 ms. The |
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10 | * interrupt vector is 0x69. |
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11 | * |
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12 | * All page references are to the MVME166/MVME167/MVME187 Single Board |
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13 | * Computer Programmer's Reference Guide (MVME187PG/D2) with the April |
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14 | * 1993 supplements/addenda (MVME187PG/D2A1). |
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15 | * |
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16 | * COPYRIGHT (c) 1989-1999. |
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17 | * On-Line Applications Research Corporation (OAR). |
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18 | * |
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19 | * The license and distribution terms for this file may be |
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20 | * found in the file LICENSE in this distribution or at |
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21 | * http://www.rtems.org/license/LICENSE. |
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22 | * |
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23 | * Modifications of respective RTEMS files: |
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24 | * Copyright (c) 1998, National Research Council of Canada |
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25 | */ |
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26 | |
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27 | #include <stdlib.h> |
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28 | #include <bsp.h> |
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29 | |
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30 | #define MS_COUNT 1000 /* T2's countdown constant (1 ms) */ |
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31 | #define CLOCK_INT_LEVEL 6 /* T2's interrupt level */ |
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32 | #define CLOCK_VECTOR (VBR0 * 0x10 + 0x9) /* T2 is vector $X9 (p. 2-71)*/ |
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33 | |
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34 | /* |
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35 | * These are declared in rtems/c/src/lib/include/clockdrv.h |
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36 | * In other BSPs, rtems_clock_major is set to the largest possible value |
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37 | * (which is almost certainly greater than the number of I/O devices) to |
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38 | * indicate that this device has not been initialized yet. The actual |
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39 | * device number is supplied during initialization. We do not do that. |
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40 | * |
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41 | * Initialized data ends up the the .data section. This causes two problems: |
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42 | * 1) the .data section is no longer ROMable because we need to write into |
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43 | * it. 2) The initial value is correct only after a download. On subsequent |
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44 | * program restarts, the value is not re-initialized but left to whatever it |
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45 | * was when the previous run terminated or aborted. If we depend on some |
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46 | * global variable value, we must initialize that value explicitly in code |
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47 | * at boot time. |
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48 | */ |
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49 | rtems_device_major_number rtems_clock_major; |
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50 | rtems_device_minor_number rtems_clock_minor; |
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51 | |
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52 | /* |
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53 | * Clock_driver_ticks is a monotonically increasing counter of the number of |
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54 | * VMEchip2 timer #2 ticks since the driver was initialized. |
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55 | */ |
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56 | volatile uint32_t Clock_driver_ticks; |
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57 | |
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58 | /* |
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59 | * Clock_isrs is the number of clock ISRs until the next invocation of the |
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60 | * RTEMS clock tick routine. This clock tick device driver gets an interrupt |
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61 | * once a millisecond and counts down until the length of time between the |
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62 | * user configured microseconds per tick has passed. This allows the clock |
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63 | * device to "tick" faster than the kernel clock. Of course, the kernel clock |
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64 | * cannot tick faster than the hardware clock. Therefore, the kernel clock |
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65 | * ticks cannot occur more frequently than every 1 millisecond. |
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66 | */ |
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67 | uint32_t Clock_isrs; |
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68 | |
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69 | /* |
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70 | * Records the previous clock ISR (should be NULL) |
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71 | */ |
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72 | rtems_isr_entry Old_ticker; |
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73 | |
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74 | /* |
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75 | * Called when the kernel exits. |
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76 | */ |
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77 | void clock_exit( void ); |
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78 | |
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79 | /* |
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80 | * VMEchip2_T2_isr |
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81 | * |
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82 | * C ISR Handler. Increment the number of internal ticks. If it is time for a |
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83 | * kernel clock tick (if Clock_isrs == 1), call rtems_clock_tick() to signal |
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84 | * the event and reset the Clock_isrs counter; else, just decrement it. |
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85 | * |
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86 | * Input parameters: |
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87 | * vector number |
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88 | * |
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89 | * Output parameters: NONE |
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90 | * |
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91 | * Return values: NONE |
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92 | */ |
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93 | rtems_isr VMEchip2_T2_isr( |
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94 | rtems_vector_number vector |
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95 | ) |
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96 | { |
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97 | char overflow; /* Content of overflow counter */ |
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98 | long i; |
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99 | long ct; /* Number of T2 ticks per RTEMS ticks */ |
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100 | |
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101 | ct = rtems_configuration_get_microseconds_per_tick() / 1000; |
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102 | |
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103 | /* |
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104 | * May have missed interrupts, so should look at the overflow counter. |
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105 | */ |
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106 | lcsr->intr_clear |= 0x02000000; /* Clear the interrupt */ |
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107 | overflow = (lcsr->board_ctl >> 12) & 0xF; |
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108 | lcsr->board_ctl |= 0x400; /* Reset overflow counter */ |
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109 | |
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110 | /* Attempt to protect against one more period */ |
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111 | if ( overflow == 0 ) |
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112 | overflow = 16; |
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113 | |
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114 | Clock_driver_ticks += overflow; /* One or more internal ticks */ |
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115 | |
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116 | if ( Clock_isrs <= overflow ) { |
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117 | /* If its time for kernel clock ticks, signal the events to RTEMS */ |
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118 | for( i = overflow - Clock_isrs; i >= 0; i -= ct ) { |
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119 | rtems_clock_tick(); |
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120 | } |
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121 | /* Reset the counter */ |
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122 | Clock_isrs = (uint32_t)-i; |
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123 | } |
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124 | else |
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125 | Clock_isrs -= overflow; |
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126 | } |
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127 | |
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128 | /* |
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129 | * VMEchip2_T2_initialize |
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130 | * |
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131 | * Initialize the VMEchip2 Tick Timer #2. |
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132 | * |
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133 | * THE VMECHIP2 PRESCALER REGISTER IS ASSUMED TO BE SET! |
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134 | * The prescaler is used by all VMEchip2 timers, including the VMEbus grant |
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135 | * timeout counter, the DMAC time off timer, the DMAC timer on timer, and the |
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136 | * VMEbus global timeout timer. The prescaler value is normally set by the |
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137 | * boot ROM to provide a 1 MHz clock to the timers. For a 25 MHz MVME167, the |
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138 | * prescaler value should be 0xE7 (page 2-63). |
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139 | * |
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140 | * Input parameters: NONE |
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141 | * |
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142 | * Output paremeters: NONE |
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143 | * |
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144 | * Return values: NONE |
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145 | */ |
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146 | void VMEchip2_T2_initialize( void ) |
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147 | { |
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148 | Clock_driver_ticks = 0; |
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149 | Clock_isrs = rtems_configuration_get_microseconds_per_tick() / 1000; |
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150 | |
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151 | lcsr->intr_ena &= 0xFDFFFFFF; /* Disable tick timer 2 interrupt */ |
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152 | lcsr->intr_clear = 0x02000000; /* Clear tick timer 2 interrupt */ |
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153 | lcsr->intr_level[0] = /* Set tick timer 2 interrupt level */ |
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154 | (lcsr->intr_level[0] & 0xFFFFFF0F ) | (CLOCK_INT_LEVEL << 4); |
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155 | lcsr->timer_cmp_2 = MS_COUNT; /* Period in compare register */ |
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156 | lcsr->timer_cnt_2 = 0; /* Clear tick timer 2 counter */ |
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157 | Old_ticker = /* Install C ISR */ |
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158 | (rtems_isr_entry) set_vector( VMEchip2_T2_isr, CLOCK_VECTOR, 1 ); |
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159 | lcsr->board_ctl |= 0x700; /* Start tick timer 2, reset-on-compare, */ |
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160 | /* and clear tick timer 2 overflow counter */ |
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161 | lcsr->intr_ena |= 0x02000000; /* Enable tick timer 2 interrupt */ |
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162 | lcsr->vector_base |= 0x00800000;/* Unmask VMEchip2 interrupts */ |
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163 | atexit( clock_exit ); /* Turn off T2 interrupts when we exit */ |
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164 | } |
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165 | |
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166 | /* |
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167 | * clock_exit |
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168 | * |
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169 | * This routine stops the VMEchip2 T2 timer, disables its interrupt, and |
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170 | * re-install the old interrupt vectors. |
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171 | * |
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172 | * Input parameters: NONE |
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173 | * |
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174 | * Output parameters: NONE |
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175 | * |
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176 | * Return values: NONE |
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177 | * |
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178 | */ |
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179 | void clock_exit( void ) |
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180 | { |
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181 | lcsr->board_ctl &= 0xFFFFFEFF; /* Stop tick timer 2 */ |
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182 | lcsr->intr_ena &= 0xFDFFFFFF; /* Disable tick timer 2 interrupt */ |
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183 | lcsr->intr_clear = 0x02000000; /* Clear tick timer 2 interrupt */ |
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184 | |
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185 | set_vector( Old_ticker, CLOCK_VECTOR, 1 ); |
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186 | } |
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187 | |
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188 | /* |
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189 | * Clock_initialize() |
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190 | * prototyped in rtems/c/src/lib/include/clockdrv.h. |
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191 | * |
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192 | * Input parameters: |
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193 | * major - console device major number |
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194 | * minor - console device minor number |
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195 | * ALWAYS 0 IN VERSION 3.6.0 OF RTEMS! |
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196 | * Probably provided for symmetry with the other I/O calls. |
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197 | * arg - pointer to optional device driver arguments |
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198 | * ALWAYS NULL IN VERSION 3.6.0 OF RTEMS! |
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199 | * |
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200 | * Output paremeters: NONE |
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201 | * |
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202 | * Return values: |
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203 | * rtems_device_driver status code |
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204 | */ |
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205 | rtems_device_driver Clock_initialize( |
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206 | rtems_device_major_number major, |
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207 | rtems_device_minor_number minor, |
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208 | void *pargp |
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209 | ) |
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210 | { |
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211 | VMEchip2_T2_initialize(); |
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212 | |
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213 | /* |
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214 | * Make major/minor avail to others such as shared memory driver |
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215 | */ |
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216 | rtems_clock_major = major; |
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217 | rtems_clock_minor = minor; |
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218 | |
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219 | return RTEMS_SUCCESSFUL; |
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220 | } |
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