diff --git a/drivers/rtc/rtc-rzn1.c b/drivers/rtc/rtc-rzn1.c
index 33c7ef5c1eba..8c3dbbc34717 100644
--- a/drivers/rtc/rtc-rzn1.c
+++ b/drivers/rtc/rtc-rzn1.c
@@ -19,6 +19,7 @@
 #include <linux/iopoll.h>
 #include <linux/module.h>
 #include <linux/mod_devicetable.h>
+#include <linux/of.h>
 #include <linux/platform_device.h>
 #include <linux/pm_runtime.h>
 #include <linux/rtc.h>
@@ -66,6 +67,10 @@
 #define RZN1_RTC_TIMEC 0x68
 #define RZN1_RTC_CALC 0x6c
 
+struct rzn1_rtc_data {
+	bool has_subu;
+};
+
 struct rzn1_rtc {
 	struct rtc_device *rtcdev;
 	void __iomem *base;
@@ -405,6 +410,7 @@ static void rzn1_rtc_disable_hardware(void *data)
 
 static int rzn1_rtc_probe(struct platform_device *pdev)
 {
+	const struct rzn1_rtc_data *data;
 	struct device *dev = &pdev->dev;
 	unsigned long rate = 32768;
 	struct rzn1_rtc *rtc;
@@ -412,6 +418,10 @@ static int rzn1_rtc_probe(struct platform_device *pdev)
 	struct clk *xtal;
 	int irq, ret;
 
+	data = of_device_get_match_data(dev);
+	if (!data)
+		return -ENODEV;
+
 	rtc = devm_kzalloc(dev, sizeof(*rtc), GFP_KERNEL);
 	if (!rtc)
 		return -ENOMEM;
@@ -455,8 +465,12 @@ static int rzn1_rtc_probe(struct platform_device *pdev)
 		if (rate < 32000 || rate > BIT(22))
 			return -EOPNOTSUPP;
 
-		if (rate != 32768)
+		if (rate != 32768 || !data->has_subu)
 			scmp_val = RZN1_RTC_CTL0_SLSB_SCMP;
+	} else if (!data->has_subu) {
+		/* xtal is NULL here */
+		return dev_err_probe(dev, -EOPNOTSUPP,
+				     "No valid XTAL provided and SUBU mode not supported\n");
 	}
 
 	/* Calculate the duration of two RTC_PCLK clock cycles */
@@ -509,8 +523,12 @@ static int rzn1_rtc_probe(struct platform_device *pdev)
 	return devm_rtc_register_device(rtc->rtcdev);
 }
 
+static const struct rzn1_rtc_data rzn1_rtc_rzn1_data = {
+	.has_subu = true,
+};
+
 static const struct of_device_id rzn1_rtc_of_match[] = {
-	{ .compatible	= "renesas,rzn1-rtc" },
+	{ .compatible	= "renesas,rzn1-rtc", .data = &rzn1_rtc_rzn1_data },
 	{},
 };
 MODULE_DEVICE_TABLE(of, rzn1_rtc_of_match);