[PATCH v3] arm64: dts: rockchip: add SPDIF node for rk3399-rockpro64

[Katsuhiro Suzuki <katsuhiro@katsuster.net>]

This patch adds 'disabled' SPDIF sound node and related settings
of SPDIF for rk3399-rockpro64.

RockPro64 has output pins for SPDIF Tx. But RK3399 does not have
enough DMA channel for enabling SPDIF tx. Current settings are:

  - I2S0     (Req num 0, 1): Enabled : Output to 40pins header CON40
  - I2S1     (Req num 2, 3): Enabled : Output to ES8316 on board
  - I2S2     (Req num 4, 5): Enabled : Output to internal HDMI core
  - SPDIF Tx (Req num 7)   : Disabled: Output to connector J10

If users want to enable ALL sound I/Os, we need 7 DMA channels for
it. But unfortunately, RK3399 has only 6 DMA channels. So users have
to choose from the following:

  - Disable one of I2S (Ex. I2S0) and enable SPDIF tx
  - Keep enable I2S0/1/2 and disable SPDIF tx

Signed-off-by: Katsuhiro Suzuki <katsuhiro@katsuster.net>

---

Changes in v3:
  - Refine commit description why adding disabled node

Changes in v2:
  - Remove redundant status property
---
 .../boot/dts/rockchip/rk3399-rockpro64.dtsi   | 27 +++++++++++++++++++
 1 file changed, 27 insertions(+)

diff --git a/arch/arm64/boot/dts/rockchip/rk3399-rockpro64.dtsi b/arch/arm64/boot/dts/rockchip/rk3399-rockpro64.dtsi
index 6e553ff47534..58097245994a 100644
--- a/arch/arm64/boot/dts/rockchip/rk3399-rockpro64.dtsi
+++ b/arch/arm64/boot/dts/rockchip/rk3399-rockpro64.dtsi
@@ -76,6 +76,23 @@ sound {
 		dais = <&i2s1_p0>;
 	};
 
+	sound-dit {
+		compatible = "audio-graph-card";
+		label = "rockchip,rk3399";
+		dais = <&spdif_p0>;
+	};
+
+	spdif-dit {
+		compatible = "linux,spdif-dit";
+		#sound-dai-cells = <0>;
+
+		port {
+			dit_p0_0: endpoint {
+				remote-endpoint = <&spdif_p0_0>;
+			};
+		};
+	};
+
 	vcc12v_dcin: vcc12v-dcin {
 		compatible = "regulator-fixed";
 		regulator-name = "vcc12v_dcin";
@@ -698,6 +715,16 @@ &sdhci {
 	status = "okay";
 };
 
+&spdif {
+	pinctrl-0 = <&spdif_bus_1>;
+
+	spdif_p0: port {
+		spdif_p0_0: endpoint {
+			remote-endpoint = <&dit_p0_0>;
+		};
+	};
+};
+
 &spi1 {
 	status = "okay";
 
-- 
2.28.0