1 | /* |
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2 | * This file interfaces with the real-time clock found in |
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3 | * a Motorola MC146818A (common on PC hardware) |
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4 | * |
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5 | * Year 2K Notes: |
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6 | * |
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7 | * This chip only uses a two digit field to store the year. This |
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8 | * code uses the RTEMS Epoch as a pivot year. This lets us map the |
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9 | * two digit year field as follows: |
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10 | * |
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11 | * + two digit years 0-87 are mapped to 2000-2087. |
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12 | * + two digit years 88-99 are mapped to 1988-1999. |
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13 | * |
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14 | * This is less than the time span supported by RTEMS. |
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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 | #include <rtems.h> |
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24 | #include <libchip/rtc.h> |
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25 | #include <libchip/mc146818a.h> |
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26 | |
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27 | #define From_BCD( _x ) ((((_x) >> 4) * 10) + ((_x) & 0x0F)) |
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28 | #define To_BCD( _x ) ((((_x) / 10) << 4) + ((_x) % 10)) |
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29 | |
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30 | /* |
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31 | * See if chip is present |
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32 | */ |
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33 | bool mc146818a_probe( |
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34 | int minor |
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35 | ) |
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36 | { |
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37 | uint32_t mc146818a; |
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38 | getRegister_f getReg; |
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39 | uint32_t value; |
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40 | |
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41 | /* |
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42 | * Verify that chip is present and that time is valid |
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43 | */ |
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44 | mc146818a = RTC_Table[ minor ].ulCtrlPort1; |
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45 | getReg = RTC_Table[ minor ].getRegister; |
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46 | value = (*getReg)( mc146818a, MC146818A_STATUSD ); |
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47 | if ((value == 0) || (value == 0xFF)) |
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48 | return false; |
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49 | return true; |
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50 | } |
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51 | |
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52 | /* |
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53 | * Initialize chip |
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54 | */ |
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55 | static void mc146818a_initialize( |
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56 | int minor |
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57 | ) |
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58 | { |
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59 | uintptr_t mc146818a; |
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60 | setRegister_f setReg; |
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61 | |
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62 | mc146818a = RTC_Table[ minor ].ulCtrlPort1; |
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63 | setReg = RTC_Table[ minor ].setRegister; |
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64 | |
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65 | (*setReg)( |
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66 | mc146818a, |
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67 | MC146818A_STATUSA, |
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68 | MC146818ASA_DIVIDER|MC146818ASA_1024 |
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69 | ); |
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70 | (*setReg)( |
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71 | mc146818a, |
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72 | MC146818A_STATUSB, |
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73 | MC146818ASB_24HR |
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74 | ); |
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75 | } |
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76 | |
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77 | /* |
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78 | * Read time from chip |
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79 | */ |
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80 | static int mc146818a_get_time( |
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81 | int minor, |
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82 | rtems_time_of_day *time |
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83 | ) |
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84 | { |
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85 | uintptr_t mc146818a; |
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86 | getRegister_f getReg; |
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87 | uint32_t value; |
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88 | rtems_interrupt_level level; |
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89 | |
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90 | mc146818a = RTC_Table[ minor ].ulCtrlPort1; |
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91 | getReg = RTC_Table[ minor ].getRegister; |
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92 | |
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93 | /* |
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94 | * No time if power failed |
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95 | */ |
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96 | if (((*getReg)( mc146818a, MC146818A_STATUSD ) & MC146818ASD_PWR) == 0) |
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97 | return -1; |
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98 | |
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99 | /* |
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100 | * Wait for time update to complete |
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101 | */ |
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102 | rtems_interrupt_disable( level ); |
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103 | while (((*getReg)( mc146818a, MC146818A_STATUSA ) & MC146818ASA_TUP) != 0) { |
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104 | rtems_interrupt_flash( level ); |
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105 | } |
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106 | |
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107 | /* |
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108 | * Read the time (we have at least 244 usec to do this) |
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109 | */ |
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110 | value = (*getReg)( mc146818a, MC146818A_YEAR ); |
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111 | value = From_BCD( value ); |
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112 | if ( value < 88 ) |
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113 | time->year = 2000 + value; |
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114 | else |
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115 | time->year = 1900 + value; |
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116 | |
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117 | value = (*getReg)( mc146818a, MC146818A_MONTH ); |
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118 | time->month = From_BCD( value ); |
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119 | |
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120 | value = (*getReg)( mc146818a, MC146818A_DAY ); |
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121 | time->day = From_BCD( value ); |
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122 | |
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123 | value = (*getReg)( mc146818a, MC146818A_HRS ); |
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124 | time->hour = From_BCD( value ); |
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125 | |
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126 | value = (*getReg)( mc146818a, MC146818A_MIN ); |
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127 | time->minute = From_BCD( value ); |
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128 | |
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129 | value = (*getReg)( mc146818a, MC146818A_SEC ); |
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130 | rtems_interrupt_enable( level ); |
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131 | time->second = From_BCD( value ); |
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132 | time->ticks = 0; |
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133 | |
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134 | return 0; |
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135 | } |
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136 | |
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137 | /* |
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138 | * Set time into chip |
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139 | */ |
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140 | static int mc146818a_set_time( |
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141 | int minor, |
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142 | const rtems_time_of_day *time |
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143 | ) |
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144 | { |
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145 | uint32_t mc146818a; |
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146 | setRegister_f setReg; |
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147 | |
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148 | mc146818a = RTC_Table[ minor ].ulCtrlPort1; |
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149 | setReg = RTC_Table[ minor ].setRegister; |
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150 | |
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151 | /* |
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152 | * Stop the RTC |
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153 | */ |
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154 | (*setReg)( mc146818a, MC146818A_STATUSB, MC146818ASB_HALT|MC146818ASB_24HR ); |
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155 | |
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156 | if ( time->year >= 2088 ) |
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157 | rtems_fatal_error_occurred( RTEMS_INVALID_NUMBER ); |
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158 | |
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159 | (*setReg)( mc146818a, MC146818A_YEAR, To_BCD(time->year % 100) ); |
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160 | (*setReg)( mc146818a, MC146818A_MONTH, To_BCD(time->month) ); |
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161 | (*setReg)( mc146818a, MC146818A_DAY, To_BCD(time->day) ); |
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162 | (*setReg)( mc146818a, MC146818A_HRS, To_BCD(time->hour) ); |
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163 | (*setReg)( mc146818a, MC146818A_MIN, To_BCD(time->minute) ); |
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164 | (*setReg)( mc146818a, MC146818A_SEC, To_BCD(time->second) ); |
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165 | |
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166 | /* |
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167 | * Restart the RTC |
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168 | */ |
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169 | (*setReg)( mc146818a, MC146818A_STATUSB, MC146818ASB_24HR ); |
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170 | return 0; |
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171 | } |
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172 | |
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173 | /* |
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174 | * Driver function table |
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175 | */ |
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176 | rtc_fns mc146818a_fns = { |
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177 | mc146818a_initialize, |
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178 | mc146818a_get_time, |
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179 | mc146818a_set_time |
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180 | }; |
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