The schematics label it as SCIF0 debug port.

Signed-off-by: Wolfram Sang <wsa+renesas@sang-engineering.com>
---

Change since v1: added alias

 .../arm64/boot/dts/renesas/r8a779f0-spider-cpu.dtsi | 13 +++++++++++++
 arch/arm64/boot/dts/renesas/r8a779f0-spider.dts     |  1 +
 2 files changed, 14 insertions(+)

diff --git a/arch/arm64/boot/dts/renesas/r8a779f0-spider-cpu.dtsi b/arch/arm64/boot/dts/renesas/r8a779f0-spider-cpu.dtsi
index 3208d2148768..7a62afb64204 100644
--- a/arch/arm64/boot/dts/renesas/r8a779f0-spider-cpu.dtsi
+++ b/arch/arm64/boot/dts/renesas/r8a779f0-spider-cpu.dtsi
@@ -68,6 +68,11 @@ i2c4_pins: i2c4 {
 		function = "i2c4";
 	};
 
+	scif0_pins: scif0 {
+		groups = "scif0_data", "scif0_ctrl";
+		function = "scif0";
+	};
+
 	scif_clk_pins: scif_clk {
 		groups = "scif_clk";
 		function = "scif_clk";
@@ -79,6 +84,14 @@ &rwdt {
 	status = "okay";
 };
 
+&scif0 {
+	pinctrl-0 = <&scif0_pins>;
+	pinctrl-names = "default";
+
+	uart-has-rtscts;
+	status = "okay";
+};
+
 &scif_clk {
 	clock-frequency = <24000000>;
 };
diff --git a/arch/arm64/boot/dts/renesas/r8a779f0-spider.dts b/arch/arm64/boot/dts/renesas/r8a779f0-spider.dts
index 954ba227bfa7..2c1fe4330c2b 100644
--- a/arch/arm64/boot/dts/renesas/r8a779f0-spider.dts
+++ b/arch/arm64/boot/dts/renesas/r8a779f0-spider.dts
@@ -15,6 +15,7 @@ / {
 
 	aliases {
 		serial0 = &hscif0;
+		serial1 = &scif0;
 	};
 
 	chosen {
-- 
2.35.1

On Tue, Jun 14, 2022 at 9:30 PM Wolfram Sang
<wsa+renesas@sang-engineering.com> wrote:
> The schematics label it as SCIF0 debug port.
>
> Signed-off-by: Wolfram Sang <wsa+renesas@sang-engineering.com>
> ---
>
> Change since v1: added alias

Reviewed-by: Geert Uytterhoeven <geert+renesas@glider.be>
i.e. will queue in renesas-devel for v5.20.

Gr{oetje,eeting}s,

                        Geert

--
Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- geert@linux-m68k.org

In personal conversations with technical people, I call myself a hacker. But
when I'm talking to journalists I just say "programmer" or something like that.
                                -- Linus Torvalds