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517460d3a9
When we try to query the time from the RTC CMOS, we try to check if the CMOS is updated. If it is updated for a long period of time (as a result of hardware malfunction), break the loop and return Unix epoch time.
107 lines
2.6 KiB
C++
107 lines
2.6 KiB
C++
/*
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* Copyright (c) 2018-2020, Andreas Kling <kling@serenityos.org>
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*
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* SPDX-License-Identifier: BSD-2-Clause
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*/
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#include <AK/Time.h>
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#include <Kernel/CMOS.h>
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#include <Kernel/IO.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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static 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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// Note: Let's wait 0.01 seconds until we stop trying to query the RTC CMOS
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size_t time_passed_in_milliseconds = 0;
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bool update_in_progress_ended_successfully = false;
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while (time_passed_in_milliseconds < 100) {
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if (!update_in_progress()) {
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update_in_progress_ended_successfully = true;
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break;
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}
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IO::delay(1000);
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time_passed_in_milliseconds++;
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}
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if (!update_in_progress_ended_successfully) {
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year = 1970;
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month = 1;
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day = 1;
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hour = 0;
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minute = 0;
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second = 0;
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return;
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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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bool is_pm = hour & 0x80;
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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 & 0x7F);
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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)) {
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// In the 12 hour clock, midnight and noon are 12, not 0. Map it to 0.
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hour %= 12;
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if (is_pm)
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hour += 12;
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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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dmesgln("RTC: Year: {}, month: {}, day: {}, hour: {}, minute: {}, second: {}", year, month, day, hour, minute, second);
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time_t days_since_epoch = years_to_days_since_epoch(year) + day_of_year(year, month, day);
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return ((days_since_epoch * 24 + hour) * 60 + minute) * 60 + second;
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}
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}
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