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/*
* Copyright (c) 2018-2020, Andreas Kling <kling@serenityos.org>
*
* SPDX-License-Identifier: BSD-2-Clause
*/
#include <AK/Time.h>
#include <Kernel/CMOS.h>
#include <Kernel/IO.h>
#include <Kernel/RTC.h>
namespace RTC {
static time_t s_boot_time;
void initialize()
{
s_boot_time = now();
}
time_t boot_time()
{
return s_boot_time;
}
static bool update_in_progress()
{
return CMOS::read(0x0a) & 0x80;
}
static u8 bcd_to_binary(u8 bcd)
{
return (bcd & 0x0F) + ((bcd >> 4) * 10);
}
static bool try_to_read_registers(unsigned& year, unsigned& month, unsigned& day, unsigned& hour, unsigned& minute, unsigned& second)
{
// Note: Let's wait 0.01 seconds until we stop trying to query the RTC CMOS
size_t time_passed_in_milliseconds = 0;
bool update_in_progress_ended_successfully = false;
while (time_passed_in_milliseconds < 100) {
if (!update_in_progress()) {
update_in_progress_ended_successfully = true;
break;
}
IO::delay(1000);
time_passed_in_milliseconds++;
}
if (!update_in_progress_ended_successfully) {
year = 1970;
month = 1;
day = 1;
hour = 0;
minute = 0;
second = 0;
return false;
}
u8 status_b = CMOS::read(0x0b);
second = CMOS::read(0x00);
minute = CMOS::read(0x02);
hour = CMOS::read(0x04);
day = CMOS::read(0x07);
month = CMOS::read(0x08);
year = CMOS::read(0x09);
bool is_pm = hour & 0x80;
if (!(status_b & 0x04)) {
second = bcd_to_binary(second);
minute = bcd_to_binary(minute);
hour = bcd_to_binary(hour & 0x7F);
day = bcd_to_binary(day);
month = bcd_to_binary(month);
year = bcd_to_binary(year);
}
if (!(status_b & 0x02)) {
// In the 12 hour clock, midnight and noon are 12, not 0. Map it to 0.
hour %= 12;
if (is_pm)
hour += 12;
}
year += 2000;
return true;
}
time_t now()
{
auto check_registers_against_preloaded_values = [](unsigned year, unsigned month, unsigned day, unsigned hour, unsigned minute, unsigned second) {
unsigned checked_year, checked_month, checked_day, checked_hour, checked_minute, checked_second;
if (!try_to_read_registers(checked_year, checked_month, checked_day, checked_hour, checked_minute, checked_second))
return false;
return checked_year == year && checked_month == month && checked_day == day && checked_hour == hour && checked_minute == minute && checked_second == second;
};
unsigned year, month, day, hour, minute, second;
bool did_read_rtc_sucessfully = false;
for (size_t attempt = 0; attempt < 5; attempt++) {
if (!try_to_read_registers(year, month, day, hour, minute, second))
break;
if (check_registers_against_preloaded_values(year, month, day, hour, minute, second)) {
did_read_rtc_sucessfully = true;
break;
}
}
dmesgln("RTC: {} Year: {}, month: {}, day: {}, hour: {}, minute: {}, second: {}", (did_read_rtc_sucessfully ? "" : "(failed to read)"), year, month, day, hour, minute, second);
time_t days_since_epoch = years_to_days_since_epoch(year) + day_of_year(year, month, day);
return ((days_since_epoch * 24 + hour) * 60 + minute) * 60 + second;
}
}
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