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113 lines
3.6 KiB
C
113 lines
3.6 KiB
C
// Copyright (c) 2023-2026 Chris (boreddevnl)
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// This software is released under the GNU General Public License v3.0. See LICENSE file for details.
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// This header needs to maintain in any file it is present in, as per the GPL license terms.
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#include "rtc.h"
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#include "io.h"
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#define CMOS_ADDRESS 0x70
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#define CMOS_DATA 0x71
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static int updating_rtc() {
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outb(CMOS_ADDRESS, 0x0A);
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return (inb(CMOS_DATA) & 0x80);
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}
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static uint8_t get_rtc_register(int reg) {
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outb(CMOS_ADDRESS, reg);
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return inb(CMOS_DATA);
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}
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void rtc_get_datetime(int *year, int *month, int *day, int *hour, int *minute, int *second) {
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uint8_t century;
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uint8_t last_second;
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uint8_t last_minute;
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uint8_t last_hour;
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uint8_t last_day;
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uint8_t last_month;
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uint8_t last_year;
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uint8_t last_century;
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uint8_t registerB;
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while (updating_rtc());
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*second = get_rtc_register(0x00);
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*minute = get_rtc_register(0x02);
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*hour = get_rtc_register(0x04);
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*day = get_rtc_register(0x07);
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*month = get_rtc_register(0x08);
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*year = get_rtc_register(0x09);
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do {
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last_second = *second;
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last_minute = *minute;
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last_hour = *hour;
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last_day = *day;
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last_month = *month;
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last_year = *year;
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while (updating_rtc());
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*second = get_rtc_register(0x00);
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*minute = get_rtc_register(0x02);
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*hour = get_rtc_register(0x04);
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*day = get_rtc_register(0x07);
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*month = get_rtc_register(0x08);
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*year = get_rtc_register(0x09);
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} while( (last_second != *second) || (last_minute != *minute) || (last_hour != *hour) ||
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(last_day != *day) || (last_month != *month) || (last_year != *year) );
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registerB = get_rtc_register(0x0B);
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// Convert BCD to binary values if necessary
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if (!(registerB & 0x04)) {
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*second = (*second & 0x0F) + ((*second / 16) * 10);
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*minute = (*minute & 0x0F) + ((*minute / 16) * 10);
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*hour = ( (*hour & 0x0F) + (((*hour & 0x70) / 16) * 10) ) | (*hour & 0x80);
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*day = (*day & 0x0F) + ((*day / 16) * 10);
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*month = (*month & 0x0F) + ((*month / 16) * 10);
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*year = (*year & 0x0F) + ((*year / 16) * 10);
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}
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// Convert 12 hour clock to 24 hour clock if necessary
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if (!(registerB & 0x02) && (*hour & 0x80)) {
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*hour = ((*hour & 0x7F) + 12) % 24;
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}
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// Calculate full year
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*year += 2000;
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}
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static void set_rtc_register(int reg, uint8_t value) {
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outb(CMOS_ADDRESS, reg);
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outb(CMOS_DATA, value);
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}
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void rtc_set_datetime(int year, int month, int day, int hour, int minute, int second) {
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uint8_t registerB = get_rtc_register(0x0B);
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// Disable NMI and start update
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outb(CMOS_ADDRESS, 0x8B);
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uint8_t prev_b = inb(CMOS_DATA);
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outb(CMOS_DATA, prev_b | 0x80); // Set SET bit to prevent updates while writing
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if (year >= 2000) year -= 2000;
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if (!(registerB & 0x04)) {
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// Convert binary to BCD
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second = ((second / 10) << 4) | (second % 10);
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minute = ((minute / 10) << 4) | (minute % 10);
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hour = ((hour / 10) << 4) | (hour % 10);
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day = ((day / 10) << 4) | (day % 10);
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month = ((month / 10) << 4) | (month % 10);
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year = ((year / 10) << 4) | (year % 10);
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}
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set_rtc_register(0x00, (uint8_t)second);
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set_rtc_register(0x02, (uint8_t)minute);
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set_rtc_register(0x04, (uint8_t)hour);
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set_rtc_register(0x07, (uint8_t)day);
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set_rtc_register(0x08, (uint8_t)month);
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set_rtc_register(0x09, (uint8_t)year);
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// Re-enable updates
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outb(CMOS_ADDRESS, 0x8B);
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outb(CMOS_DATA, prev_b & ~0x80);
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}
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