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07ca753124
It turns out some BIOS vendors don't support non-BCD date/time mode, but we were relying on it being available. We no longer do this, but instead check whether the BIOS claims to provide BCD or regular binary values for its date/time data.
144 lines
3.0 KiB
C++
144 lines
3.0 KiB
C++
#include <AK/Assertions.h>
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#include <Kernel/CMOS.h>
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#include <Kernel/RTC.h>
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namespace RTC {
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static time_t s_boot_time;
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void initialize()
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{
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s_boot_time = now();
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}
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time_t boot_time()
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{
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return s_boot_time;
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}
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static bool update_in_progress()
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{
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return CMOS::read(0x0a) & 0x80;
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}
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inline bool is_leap_year(unsigned year)
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{
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return ((year % 4 == 0) && ((year % 100 != 0) || (year % 400) == 0));
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}
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static unsigned days_in_months_since_start_of_year(unsigned month, unsigned year)
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{
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ASSERT(month <= 11);
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unsigned days = 0;
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switch (month) {
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case 11:
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days += 30;
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[[fallthrough]];
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case 10:
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days += 31;
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[[fallthrough]];
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case 9:
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days += 30;
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[[fallthrough]];
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case 8:
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days += 31;
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[[fallthrough]];
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case 7:
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days += 31;
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[[fallthrough]];
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case 6:
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days += 30;
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[[fallthrough]];
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case 5:
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days += 31;
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[[fallthrough]];
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case 4:
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days += 30;
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[[fallthrough]];
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case 3:
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days += 31;
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[[fallthrough]];
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case 2:
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if (is_leap_year(year))
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days += 29;
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else
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days += 28;
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[[fallthrough]];
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case 1:
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days += 31;
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}
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return days;
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}
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static unsigned days_in_years_since_epoch(unsigned year)
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{
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unsigned days = 0;
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while (year > 1969) {
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days += 365;
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if (is_leap_year(year))
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++days;
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--year;
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}
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return days;
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}
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u8 bcd_to_binary(u8 bcd)
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{
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return (bcd & 0x0F) + ((bcd >> 4) * 10);
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}
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void read_registers(unsigned& year, unsigned& month, unsigned& day, unsigned& hour, unsigned& minute, unsigned& second)
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{
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while (update_in_progress())
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;
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u8 status_b = CMOS::read(0x0b);
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second = CMOS::read(0x00);
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minute = CMOS::read(0x02);
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hour = CMOS::read(0x04);
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day = CMOS::read(0x07);
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month = CMOS::read(0x08);
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year = CMOS::read(0x09);
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if (!(status_b & 0x04)) {
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second = bcd_to_binary(second);
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minute = bcd_to_binary(minute);
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hour = bcd_to_binary(hour & 0x70);
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day = bcd_to_binary(day);
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month = bcd_to_binary(month);
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year = bcd_to_binary(year);
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}
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if (!(status_b & 0x02) && (hour & 0x80)) {
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hour = ((hour & 0x7F) + 12) % 24;
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}
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year += 2000;
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}
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time_t now()
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{
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// FIXME: We should probably do something more robust here.
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// Perhaps read all the values twice and verify that they were identical.
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// We don't want to be caught in the middle of an RTC register update.
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while (update_in_progress())
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;
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unsigned year, month, day, hour, minute, second;
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read_registers(year, month, day, hour, minute, second);
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kprintf("year: %d, month: %d, day: %d\n", year, month, day);
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ASSERT(year >= 2018);
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return days_in_years_since_epoch(year - 1) * 86400
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+ days_in_months_since_start_of_year(month - 1, year) * 86400
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+ (day - 1) * 86400
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+ hour * 3600
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+ minute * 60
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+ second;
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}
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}
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