Kernel: Reorganize Arch/x86 directory to Arch/x86_64 after i686 removal

No functional change.

Kernel/Arch/x86_64/RTC.cpp

@@ -0,0 +1,119 @@
+/*
+ * Copyright (c) 2018-2020, Andreas Kling <kling@serenityos.org>
+ *
+ * SPDX-License-Identifier: BSD-2-Clause
+ */
+
+#include <AK/Format.h>
+#include <AK/Time.h>
+#include <Kernel/Arch/Delay.h>
+#include <Kernel/Arch/x86_64/CMOS.h>
+#include <Kernel/Arch/x86_64/RTC.h>
+
+namespace Kernel::RTC {
+
+static time_t s_boot_time;
+
+void initialize()
+{
+    s_boot_time = now();
+}
+
+Time boot_time()
+{
+    return Time::from_timespec({ s_boot_time, 0 });
+}
+
+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;
+        }
+        microseconds_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_successfully = 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_successfully = true;
+            break;
+        }
+    }
+
+    dmesgln("RTC: {} Year: {}, month: {}, day: {}, hour: {}, minute: {}, second: {}", (did_read_rtc_successfully ? "" : "(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;
+}
+
+}