rtc.c

Go to the documentation of this file.

 
#include <stdbool.h>
#include <stdint.h>
#include <string.h>
 
#include <sys/kassert.h>
#include <sys/kdebug.h>
#include <sys/ktime.h>
 
#include "ioport.h"
 
#define RTC_SECONDS     0x00
#define RTC_MINUTES     0x02
#define RTC_HOURS       0x04
#define RTC_WEEKDAY     0x06
#define RTC_DAY         0x07
#define RTC_MONTH       0x08
#define RTC_YEAR        0x09
 
UnixEpoch RTC_ReadTime();
 
void
RTC_Init()
{
    uint64_t startTSC, stopTSC;
    UnixEpoch first, second;
 
    kprintf("RTC: Measuring CPU clock...\n");
 
    first = RTC_ReadTime();
    while (1) {
        second = RTC_ReadTime();
        if (first != second)
            break;
        first = second;
    }
    startTSC = Time_GetTSC();
 
    first = RTC_ReadTime();
    while (1) {
        second = RTC_ReadTime();
        if (first != second)
            break;
        first = second;
    }
    stopTSC = Time_GetTSC();
 
    kprintf("RTC: %lld Ticks Per Second: %lld\n", second, stopTSC - startTSC);
 
    KTime_SetTime(second, stopTSC, stopTSC - startTSC);
}
 
static inline uint8_t
RTC_ReadReg(uint8_t reg)
{
    outb(0x70, reg);
    return inb(0x71);
}
 
UnixEpoch
RTC_ReadTime()
{
    KTime tm;
    bool isPM = false;
    uint8_t flags = RTC_ReadReg(0x0B);
 
    // Read RTC
    tm.sec = RTC_ReadReg(RTC_SECONDS);
    tm.min = RTC_ReadReg(RTC_MINUTES);
    tm.hour = RTC_ReadReg(RTC_HOURS);
    tm.wday = RTC_ReadReg(RTC_WEEKDAY);
    tm.mday = RTC_ReadReg(RTC_DAY);
    tm.month = RTC_ReadReg(RTC_MONTH);
    tm.year = RTC_ReadReg(RTC_YEAR);
 
    // Convert BCD & 24-hour checks
    if (tm.hour & 0x80) {
        isPM = true;
    }
    if ((flags & 0x04) == 0) {
#define BCD_TO_BIN(_B) ((_B & 0x0F) + ((_B >> 4) * 10))
        tm.sec = BCD_TO_BIN(tm.sec);
        tm.min = BCD_TO_BIN(tm.min);
        tm.hour = BCD_TO_BIN((tm.hour & 0x7F));
        tm.wday = BCD_TO_BIN(tm.wday);
        tm.mday = BCD_TO_BIN(tm.mday);
        tm.month = BCD_TO_BIN(tm.month);
        tm.year = BCD_TO_BIN(tm.year);
    }
    if (((flags & 0x02) == 0) && isPM) {
        tm.hour = (tm.hour + 12) % 24;
    }
 
    tm.year += 2000;
    tm.yday = -1;
 
    tm.wday -= 1;
    tm.month -= 1;
 
//    KTime_SetTime(&tm);
    return KTime_ToEpoch(&tm);
}