lunaix-os/hal/rtc.c

   1 /**
   2  * @file rtc.c
   3  * @author Lunaixsky
   4  * @brief RTC & CMOS abstraction. Reference: MC146818A & Intel Series 500 PCH datasheet
   5  * @version 0.1
   6  * @date 2022-03-07
   7  *
   8  * @copyright Copyright (c) 2022
   9  *
  10  */
  11 #include <hal/rtc.h>
  12 #include <klibc/string.h>
  13
  14 void
  15 rtc_init() {
  16     uint8_t regA = rtc_read_reg(RTC_REG_A | WITH_NMI_DISABLED);
  17     regA = (regA & ~0x7f) | RTC_FREQUENCY_1024HZ | RTC_DIVIDER_33KHZ;
  18     rtc_write_reg(RTC_REG_A | WITH_NMI_DISABLED, regA);
  19
  20     // Make sure the rtc timer is disabled by default
  21     rtc_disable_timer();
  22 }
  23
  24 uint8_t
  25 rtc_read_reg(uint8_t reg_selector)
  26 {
  27     io_outb(RTC_INDEX_PORT, reg_selector);
  28     return io_inb(RTC_TARGET_PORT);
  29 }
  30
  31 void
  32 rtc_write_reg(uint8_t reg_selector, uint8_t val)
  33 {
  34     io_outb(RTC_INDEX_PORT, reg_selector);
  35     io_outb(RTC_TARGET_PORT, val);
  36 }
  37
  38 uint8_t
  39 bcd2dec(uint8_t bcd)
  40 {
  41     return ((bcd & 0xF0) >> 1) + ((bcd & 0xF0) >> 3) + (bcd & 0xf);
  42 }
  43
  44 int
  45 rtc_date_same(rtc_datetime* a, rtc_datetime* b) {
  46     return a->year == b->year &&
  47            a->month == b->month &&
  48            a->day == b->day &&
  49            a->weekday == b->weekday &&
  50            a->minute == b->minute &&
  51            a->second == b->second;
  52 }
  53
  54 void
  55 rtc_get_datetime(rtc_datetime* datetime)
  56 {
  57     rtc_datetime current;
  58
  59     do
  60     {
  61         while (rtc_read_reg(RTC_REG_A) & 0x80);
  62         memcpy(&current, datetime, sizeof(rtc_datetime));
  63
  64         datetime->year = rtc_read_reg(RTC_REG_YRS);
  65         datetime->month = rtc_read_reg(RTC_REG_MTH);
  66         datetime->day = rtc_read_reg(RTC_REG_DAY);
  67         datetime->weekday = rtc_read_reg(RTC_REG_WDY);
  68         datetime->hour = rtc_read_reg(RTC_REG_HRS);
  69         datetime->minute = rtc_read_reg(RTC_REG_MIN);
  70         datetime->second = rtc_read_reg(RTC_REG_SEC);
  71     } while (!rtc_date_same(datetime, &current));
  72
  73     uint8_t regbv = rtc_read_reg(RTC_REG_B);
  74
  75     // Convert from bcd to binary when needed
  76     if (!RTC_BIN_ENCODED(regbv)) {
  77         datetime->year = bcd2dec(datetime->year);
  78         datetime->month = bcd2dec(datetime->month);
  79         datetime->day = bcd2dec(datetime->day);
  80         datetime->hour = bcd2dec(datetime->hour);
  81         datetime->minute = bcd2dec(datetime->minute);
  82         datetime->second = bcd2dec(datetime->second);
  83     }
  84
  85
  86     // To 24 hour format
  87     if (!RTC_24HRS_ENCODED(regbv) && (datetime->hour >> 7)) {
  88         datetime->hour = (12 + datetime->hour & 0x80);
  89     }
  90
  91     datetime->year += RTC_CURRENT_CENTRY * 100;
  92 }
  93
  94 void
  95 rtc_enable_timer() {
  96     uint8_t regB = rtc_read_reg(RTC_REG_B | WITH_NMI_DISABLED);
  97     rtc_write_reg(RTC_REG_B | WITH_NMI_DISABLED, regB | RTC_TIMER_ON);
  98 }
  99
 100 void
 101 rtc_disable_timer() {
 102     uint8_t regB = rtc_read_reg(RTC_REG_B | WITH_NMI_DISABLED);
 103     rtc_write_reg(RTC_REG_B | WITH_NMI_DISABLED, regB & ~RTC_TIMER_ON);
 104 }