1 files changed, 91 insertions, 0 deletions
diff --git a/kernel/drivers/rtc.c b/kernel/drivers/rtc.c
new file mode 100644
index 0000000..a82864f
--- /dev/null
+++ b/kernel/drivers/rtc.c
@@ -0,0 +1,91 @@
+// MIT License, Copyright (c) 2021 Marvin Borner
+
+#include <cpu.h>
+#include <def.h>
+#include <fs.h>
+#include <mem.h>
+#include <rtc.h>
+#include <str.h>
+#include <timer.h>
+
+static u8 rtc_busy(void)
+{
+	outb(0x70, 0x0A);
+	return (inb(0x71) & 0x80) == 0x80;
+}
+
+static u8 rtc_register(u8 reg)
+{
+	outb(0x70, reg);
+	return inb(0x71);
+}
+
+static void rtc_fill(struct rtc *rtc)
+{
+	while (rtc_busy())
+		;
+
+	rtc->second = rtc_register(0x00);
+	rtc->minute = rtc_register(0x02);
+	rtc->hour = rtc_register(0x04);
+	rtc->day = rtc_register(0x07);
+	rtc->month = rtc_register(0x08);
+	rtc->year = rtc_register(0x09);
+	//obj.century = 20; //rtc_register(0x00);
+}
+
+struct rtc rtc_read(void)
+{
+	struct rtc rtc = { 0 };
+	rtc_fill(&rtc);
+
+	struct rtc last = { 0 };
+	do {
+		rtc_fill(&last);
+	} while (memcmp(&rtc, &last, sizeof(rtc)) != 0);
+
+	u32 reg_b = rtc_register(0x0B);
+
+	if (!(reg_b & 0x04)) {
+		rtc.second = (u8)((rtc.second & 0x0F) + ((rtc.second / 16) * 10));
+		rtc.minute = (u8)((rtc.minute & 0x0F) + ((rtc.minute / 16) * 10));
+		rtc.hour = (u8)(((rtc.hour & 0x0F) + (((rtc.hour & 0x70) / 16) * 10)) |
+				(rtc.hour & 0x80));
+		rtc.day = (u8)((rtc.day & 0x0F) + ((rtc.day / 16) * 10));
+		rtc.month = (u8)((rtc.month & 0x0F) + ((rtc.month / 16) * 10));
+		rtc.year = (rtc.year & 0x0F) + ((rtc.year / 16) * 10);
+		/* rtc.century = (century & 0x0F) + ((century / 16) * 10); */
+	}
+
+	if (!(reg_b & 0x02) && (rtc.hour & 0x80))
+		rtc.hour = (u8)(((rtc.hour & 0x7F) + 12) % 24);
+
+	return rtc;
+}
+
+u32 rtc_stamp(void)
+{
+	struct rtc rtc = rtc_read();
+	return timer_get() + rtc.second + rtc.minute * 60 + rtc.hour * 360 + rtc.day * 360 * 24 +
+	       rtc.year * 360 * 24 * 365;
+}
+
+static res rtc_dev_read(void *buf, u32 offset, u32 count, struct device *dev)
+{
+	UNUSED(offset);
+	UNUSED(dev);
+
+	u32 stamp = rtc_stamp();
+	memcpy_user(buf, &stamp, MIN(count, sizeof(stamp)));
+
+	return MIN(count, sizeof(stamp));
+}
+
+CLEAR void rtc_install(void)
+{
+	struct device *dev = zalloc(sizeof(*dev));
+	dev->name = strdup("rtc");
+	dev->type = DEV_CHAR;
+	dev->read = rtc_dev_read;
+	device_add(dev);
+}