arm64: dts: renesas: rzg2lc-smarc: Add support for enabling MTU3

Add support for PMOD_MTU3 macro to enable MTU3 node on RZ/G2LC SMARC
EVK.

The MTU3a PWM pins on PMOD0 are muxed with SPI1. Disable SPI1, when
PMOD_MTU3 macro is enabled.
Signed-off-by: Biju Das <biju.das.jz@bp.renesas.com>
Reviewed-by: Geert Uytterhoeven <geert+renesas@glider.be>
Link: https://lore.kernel.org/r/20230707155849.86649-1-biju.das.jz@bp.renesas.comSigned-off-by: Geert Uytterhoeven <geert+renesas@glider.be>

arch/arm64/boot/dts/renesas/r9a07g044c2-smarc.dts

@@ -35,6 +35,18 @@
 /* comment the #define statement to disable SCIF1 (SER0) on PMOD1 (CN7) */
 #define PMOD1_SER0	1
 
+/*
+ * To enable MTU3a PWM on PMOD0,
+ *  - Set DIP-Switch SW1-4 to Off position.
+ *  - Set SW_RSPI_CAN macro to 0.
+ *  - Set PMOD_MTU3 macro to 1.
+ */
+#define PMOD_MTU3	0
+
+#if (PMOD_MTU3 && SW_RSPI_CAN)
+#error "Cannot set as both PMOD_MTU3 and SW_RSPI_CAN are mutually exclusive"
+#endif
+
 #include "r9a07g044c2.dtsi"
 #include "rzg2lc-smarc-som.dtsi"
 #include "rzg2lc-smarc.dtsi"

arch/arm64/boot/dts/renesas/rzg2lc-smarc-pinfunction.dtsi

@@ -50,6 +50,15 @@ i2c2_pins: i2c2 {
 			 <RZG2L_PORT_PINMUX(42, 4, 1)>; /* SCL */
 	};
 
+	mtu3_pins: mtu3 {
+		mtu3-pwm {
+			pinmux = <RZG2L_PORT_PINMUX(44, 0, 4)>, /* MTIOC3A */
+				 <RZG2L_PORT_PINMUX(44, 1, 4)>, /* MTIOC3B */
+				 <RZG2L_PORT_PINMUX(44, 2, 4)>, /* MTIOC3C */
+				 <RZG2L_PORT_PINMUX(44, 3, 4)>; /* MTIOC3D */
+		};
+	};
+
 	scif0_pins: scif0 {
 		pinmux = <RZG2L_PORT_PINMUX(38, 0, 1)>,	/* TxD */
 			 <RZG2L_PORT_PINMUX(38, 1, 1)>;	/* RxD */

arch/arm64/boot/dts/renesas/rzg2lc-smarc.dtsi

@@ -11,7 +11,6 @@
 #include "rzg2lc-smarc-pinfunction.dtsi"
 #include "rz-smarc-common.dtsi"
 
-
 / {
 	aliases {
 		serial1 = &scif1;
@@ -129,6 +128,19 @@ wm8978: codec@1a {
 	};
 };
 
+#if PMOD_MTU3
+&mtu3 {
+	pinctrl-0 = <&mtu3_pins>;
+	pinctrl-names = "default";
+
+	status = "okay";
+};
+
+&spi1 {
+	status = "disabled";
+};
+#endif
+
 /*
  * To enable SCIF1 (SER0) on PMOD1 (CN7), On connector board
  * SW1 should be at position 2->3 so that SER0_CTS# line is activated