mirror of
https://github.com/LadybirdBrowser/ladybird.git
synced 2024-11-15 07:09:43 +03:00
7c617394a1
We try to read twice from the RTC CMOS registers, and if the values are not the same for 5 attempts, we know there's a malfunction with the hardware so we declare these values as bogus in the kernel log.
119 lines
3.3 KiB
C++
119 lines
3.3 KiB
C++
/*
|
|
* 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;
|
|
}
|
|
|
|
}
|