1 files changed, 80 insertions, 0 deletions
diff --git a/drivers/rtc/emul_rtc.c b/drivers/rtc/emul_rtc.c
new file mode 100644
index 0000000000..c98c24bbb3
--- /dev/null
+++ b/drivers/rtc/emul_rtc.c
@@ -0,0 +1,80 @@
+// SPDX-License-Identifier: GPL-2.0+
+/*
+ * Copyright 2020, Heinrich Schuchardt <xypron.glpk@gmx.de>
+ *
+ * This driver emulates a real time clock based on timer ticks.
+ */
+
+#include <common.h>
+#include <div64.h>
+#include <dm.h>
+#include <generated/timestamp_autogenerated.h>
+#include <rtc.h>
+
+/**
+ * struct emul_rtc - private data for emulated RTC driver
+ */
+struct emul_rtc {
+	/**
+	 * @offset_us: microseconds from 1970-01-01 to timer_get_us() base
+	 */
+	u64 offset_us;
+	/**
+	 * @isdst: daylight saving time
+	 */
+	int isdst;
+};
+
+static int emul_rtc_get(struct udevice *dev, struct rtc_time *time)
+{
+	struct emul_rtc *priv = dev_get_priv(dev);
+	u64 now;
+
+	if (!priv->offset_us) {
+		/* Use the build date as initial time */
+		priv->offset_us = U_BOOT_EPOCH * 1000000ULL - timer_get_us();
+		priv->isdst = -1;
+	}
+
+	now = timer_get_us() + priv->offset_us;
+	do_div(now, 1000000);
+	rtc_to_tm(now, time);
+	time->tm_isdst = priv->isdst;
+
+	return 0;
+}
+
+static int emul_rtc_set(struct udevice *dev, const struct rtc_time *time)
+{
+	struct emul_rtc *priv = dev_get_priv(dev);
+
+	if (time->tm_year < 1970)
+		return -EINVAL;
+
+	priv->offset_us = rtc_mktime(time) * 1000000ULL - timer_get_us();
+
+	if (time->tm_isdst > 0)
+		priv->isdst = 1;
+	else if (time->tm_isdst < 0)
+		priv->isdst = -1;
+	else
+		priv->isdst = 0;
+
+	return 0;
+}
+
+static const struct rtc_ops emul_rtc_ops = {
+	.get = emul_rtc_get,
+	.set = emul_rtc_set,
+};
+
+U_BOOT_DRIVER(rtc_emul) = {
+	.name	= "rtc_emul",
+	.id	= UCLASS_RTC,
+	.ops	= &emul_rtc_ops,
+	.priv_auto_alloc_size = sizeof(struct emul_rtc),
+};
+
+U_BOOT_DEVICE(rtc_emul) = {
+	.name	= "rtc_emul",
+};