Basic X86 RTC code

sys/SConscript

@@ -31,6 +31,7 @@ src_amd64 = [
     "dev/x86/debugcons.c",
     "dev/x86/ide.c",
     "dev/x86/ps2.c",
+    "dev/x86/rtc.c",
     "dev/x86/sercons.c",
     "dev/x86/vgacons.c",
 ]

sys/amd64/machine.c

@@ -22,6 +22,7 @@
 
 #include "../dev/console.h"
 
+extern void RTC_Init();
 extern void PS2_Init();
 extern void PCI_Init();
 extern void IDE_Init();
@@ -140,6 +141,8 @@ void Machine_Init()
     IOAPIC_Enable(0); // Enable timer interrupts
     Thread_Init();
 
+    RTC_Init();
+
     PS2_Init();
     PCI_Init();
     IDE_Init();

sys/dev/x86/rtc.c

@@ -0,0 +1,132 @@
+
+#include <stdbool.h>
+#include <stdint.h>
+#include <string.h>
+
+#include <sys/kassert.h>
+#include <sys/kdebug.h>
+#include <sys/spinlock.h>
+
+#include "ioport.h"
+
+#define RTC_SECONDS	0x00
+#define RTC_MINUTES	0x02
+#define RTC_HOURS	0x04
+#define RTC_WEEKDAY	0x06
+#define RTC_DAY		0x07
+#define RTC_MONTH	0x08
+#define RTC_YEAR	0x09
+
+uint64_t RTC_ReadTime();
+
+void
+RTC_Init()
+{
+    RTC_ReadTime();
+}
+
+static inline uint8_t
+RTC_ReadReg(uint8_t reg)
+{
+    outb(0x70, reg);
+    return inb(0x71);
+}
+
+static bool
+RTC_IsLeapYear(uint64_t year)
+{
+    if ((year % 4) != 0)
+	return false;
+    if ((year % 100) != 0)
+	return true;
+    if ((year % 400) != 0)
+	return false;
+    return true;
+}
+
+static int
+RTC_DaysInMonth(uint64_t year, uint64_t month)
+{
+    static const uint64_t days[12] = { 31, 28, 31, 30, 31, 30, 31, 31, 30, 31, 30, 31 };
+
+    if ((month == 2) && RTC_IsLeapYear(year))
+	return 29;
+    else
+	return days[month];
+}
+
+static const char *dayOfWeek[7] = { "Sun", "Mon", "Tue", "Wed", "Thu", "Fri", "Sat" };
+static const char *months[12] = {
+    "Jan", "Feb", "Mar", "Apr", "May", "Jun",
+    "Jul", "Aug", "Sep", "Oct", "Nov", "Dec"
+};
+
+uint64_t
+RTC_ReadTime()
+{
+    uint64_t days = 0;
+    uint64_t secs = 0;
+    uint64_t y, m;
+    // Read RTC
+    bool isPM = false;
+    uint64_t seconds = RTC_ReadReg(RTC_SECONDS);
+    uint64_t minutes = RTC_ReadReg(RTC_MINUTES);
+    uint64_t hours = RTC_ReadReg(RTC_HOURS);
+    uint64_t weekday = RTC_ReadReg(RTC_WEEKDAY);
+    uint64_t day = RTC_ReadReg(RTC_DAY);
+    uint64_t month = RTC_ReadReg(RTC_MONTH);
+    uint64_t year = RTC_ReadReg(RTC_YEAR);
+    uint8_t flags = RTC_ReadReg(0x0B);
+
+    // Convert BCD & 24-hour checks
+    if (hours & 0x80) {
+	isPM = true;
+    }
+    if ((flags & 0x04) == 0) {
+#define BCD_TO_BIN(_B) ((_B & 0x0F) + ((_B >> 4) * 10))
+	seconds = BCD_TO_BIN(seconds);
+	minutes = BCD_TO_BIN(minutes);
+	hours = BCD_TO_BIN((hours & 0x7F));
+	weekday = BCD_TO_BIN(weekday);
+	day = BCD_TO_BIN(day);
+	month = BCD_TO_BIN(month);
+	year = BCD_TO_BIN(year);
+    }
+    if (((flags & 0x02) == 0) && isPM) {
+	hours = (hours + 12) % 24;
+    }
+
+    year += 2000;
+
+    kprintf("RTC: %s %s %d %02d:%02d:%02d %04d\n",
+	    dayOfWeek[weekday - 1], months[month - 1],
+	    day, hours, minutes, seconds, year);
+
+    // Convert to UNIX epoch
+    for (y = 1970; y < year; y++) {
+	if (RTC_IsLeapYear(y))
+	    days += 366;
+	else
+	    days += 365;
+    }
+
+    for (m = 0; m < month; m++) {
+	days += RTC_DaysInMonth(year, month);
+    }
+    days += day;
+
+    secs = 24 * days + hours;
+    secs = secs * 60 + minutes;
+    secs = secs * 60 + seconds;
+
+    return secs;
+}
+
+void
+Debug_Date()
+{
+    RTC_ReadTime();
+}
+
+REGISTER_DBGCMD(date, "Print date", Debug_Date);
+