diff --git a/arch/sandbox/include/asm/rtc.h b/arch/sandbox/include/asm/rtc.h
new file mode 100644
index 0000000..5ed4584
--- /dev/null
+++ b/arch/sandbox/include/asm/rtc.h
@@ -0,0 +1,28 @@
+/*
+ * Simulate an I2C real time clock
+ *
+ * Copyright (c) 2015 Google, Inc
+ * Written by Simon Glass <sjg@chromium.org>
+ *
+ * SPDX-License-Identifier:	GPL-2.0+
+ */
+
+#ifndef __asm_rtc_h
+#define __asm_rtc_h
+
+/* Register numbers in the sandbox RTC */
+enum {
+	REG_SEC		= 5,
+	REG_MIN,
+	REG_HOUR,
+	REG_MDAY,
+	REG_MON,
+	REG_YEAR,
+	REG_WDAY,
+
+	REG_RESET	= 0x20,
+
+	REG_COUNT	= 0x80,
+};
+
+#endif
diff --git a/arch/sandbox/include/asm/test.h b/arch/sandbox/include/asm/test.h
index 06e7301..91a5c79 100644
--- a/arch/sandbox/include/asm/test.h
+++ b/arch/sandbox/include/asm/test.h
@@ -46,4 +46,25 @@
  */
 void sandbox_timer_add_offset(unsigned long offset);
 
+/**
+ * sandbox_i2c_rtc_set_offset() - set the time offset from system/base time
+ *
+ * @dev:		RTC device to adjust
+ * @use_system_time:	true to use system time, false to use @base_time
+ * @offset:		RTC offset from current system/base time (-1 for no
+ *			change)
+ * @return old value of RTC offset
+ */
+long sandbox_i2c_rtc_set_offset(struct udevice *dev, bool use_system_time,
+				int offset);
+
+/**
+ * sandbox_i2c_rtc_get_set_base_time() - get and set the base time
+ *
+ * @dev:		RTC device to adjust
+ * @base_time:		New base system time (set to -1 for no change)
+ * @return old base time
+ */
+long sandbox_i2c_rtc_get_set_base_time(struct udevice *dev, long base_time);
+
 #endif