Added cmos based rtc date & time

1 files changed, 99 insertions, 0 deletions

diff --git a/src/kernel/cmos/rtc.c b/src/kernel/cmos/rtc.c
new file mode 100644
index 0000000..ed7c494
--- /dev/null
+++ b/src/kernel/cmos/rtc.c
@@ -0,0 +1,99 @@
+#include <kernel/io/io.h>
+#include <kernel/graphics/vesa.h>
+#include <kernel/acpi/acpi.h>
+
+unsigned char second;
+unsigned char minute;
+unsigned char hour;
+unsigned char day;
+unsigned char month;
+unsigned int year;
+
+int get_update_in_progress_flag() {
+    send_b(0x70, 0x0A);
+    return (receive_b(0x71) & 0x80);
+}
+
+unsigned char get_rtc_register(int reg) {
+    send_b(0x70, reg);
+    return receive_b(0x71);
+}
+
+void read_rtc() {
+    unsigned int century;
+    unsigned char last_second;
+    unsigned char last_minute;
+    unsigned char last_hour;
+    unsigned char last_day;
+    unsigned char last_month;
+    unsigned char last_year;
+    unsigned char last_century;
+    unsigned char registerB;
+
+    while (get_update_in_progress_flag());
+    second = get_rtc_register(0x00);
+    minute = get_rtc_register(0x02);
+    hour = get_rtc_register(0x04);
+    day = get_rtc_register(0x07);
+    month = get_rtc_register(0x08);
+    year = get_rtc_register(0x09);
+    century = get_rtc_register(facp->century);
+
+    // Try until the values are the same (fix for RTC updates)
+    do {
+        last_second = second;
+        last_minute = minute;
+        last_hour = hour;
+        last_day = day;
+        last_month = month;
+        last_year = year;
+        last_century = century;
+
+        while (get_update_in_progress_flag());
+        second = get_rtc_register(0x00);
+        minute = get_rtc_register(0x02);
+        hour = get_rtc_register(0x04);
+        day = get_rtc_register(0x07);
+        month = get_rtc_register(0x08);
+        year = get_rtc_register(0x09);
+        century = get_rtc_register(facp->century);
+    } while ((last_second != second) || (last_minute != minute) || (last_hour != hour) ||
+             (last_day != day) || (last_month != month) || (last_year != year) ||
+             (last_century != century));
+
+    registerB = get_rtc_register(0x0B);
+
+    if (!(registerB & 0x04)) {
+        second = (second & 0x0F) + ((second / 16) * 10);
+        minute = (minute & 0x0F) + ((minute / 16) * 10);
+        hour = ((hour & 0x0F) + (((hour & 0x70) / 16) * 10)) | (hour & 0x80);
+        day = (day & 0x0F) + ((day / 16) * 10);
+        month = (month & 0x0F) + ((month / 16) * 10);
+        year = (year & 0x0F) + ((year / 16) * 10);
+        century = (century & 0x0F) + ((century / 16) * 10);
+    }
+
+    year += century * 100;
+
+    // Convert to 24h if necessary
+    if (!(registerB & 0x02) && (hour & 0x80)) {
+        hour = ((hour & 0x7F) + 12) % 24;
+    }
+}
+
+void write_time() {
+    read_rtc();
+    vesa_draw_string("Current time: ");
+    vesa_draw_number(hour);
+    vesa_draw_string(":");
+    vesa_draw_number(minute);
+    vesa_draw_string(":");
+    vesa_draw_number(second);
+    vesa_draw_string(" ");
+    vesa_draw_number(month);
+    vesa_draw_string("/");
+    vesa_draw_number(day);
+    vesa_draw_string("/");
+    vesa_draw_number(year);
+    vesa_draw_string("\n");
+}
\ No newline at end of file