diff --git a/drivers/serial/serial_sh.c b/drivers/serial/serial_sh.c
index 0826d59ab2adbba604665b520278898130e9fa59..144a925394513d38b1677030cb97fcc5f96d84cb 100644
--- a/drivers/serial/serial_sh.c
+++ b/drivers/serial/serial_sh.c
@@ -49,9 +49,15 @@ static struct uart_port sh_sci = {
 static void sh_serial_setbrg(void)
 {
 	DECLARE_GLOBAL_DATA_PTR;
-
+#ifdef CONFIG_SCIF_USE_EXT_CLK
+	unsigned short dl = DL_VALUE(gd->baudrate, CONFIG_SH_SCIF_CLK_FREQ);
+	sci_out(&sh_sci, DL, dl);
+	/* Need wait: Clock * 1/dl × 1/16 */
+	udelay((1000000 * dl * 16 / CONFIG_SYS_CLK_FREQ) * 1000 + 1);
+#else
 	sci_out(&sh_sci, SCBRR,
 		SCBRR_VALUE(gd->baudrate, CONFIG_SH_SCIF_CLK_FREQ));
+#endif
 }
 
 static int sh_serial_init(void)
diff --git a/drivers/serial/serial_sh.h b/drivers/serial/serial_sh.h
index 4f3e22530f95a0f3e9af957a2dcac6239a7fe1f4..fe8cde4dedb5ffe3ea9c33779841038cbc9e90d6 100644
--- a/drivers/serial/serial_sh.h
+++ b/drivers/serial/serial_sh.h
@@ -735,8 +735,8 @@ static inline int scbrr_calc(struct uart_port port, int bps, int clk)
 #elif defined(__H8300H__) || defined(__H8300S__)
 #define SCBRR_VALUE(bps, clk) (((clk*1000/32)/bps)-1)
 #elif defined(CONFIG_R8A7790) || defined(CONFIG_R8A7791)
-#define SCBRR DL
-#define SCBRR_VALUE(bps, clk) (clk / bps / 16)
+#define DL_VALUE(bps, clk) (clk / bps / 16) /* External Clock */
+#define SCBRR_VALUE(bps, clk) ((clk+16*bps)/(32*bps)-1) /* Internal Clock */
 #else /* Generic SH */
 #define SCBRR_VALUE(bps, clk) ((clk+16*bps)/(32*bps)-1)
 #endif