arm64: dts: phygate-tauri-l: add overlays for RS232 and RS485

UART2 and UART4 can used in following combination,

2 x RS232:
- UART2 and UART4 without flow control
- MUX selection GPIO3_20 must be held low

1 x RS232 + 1 x RS485:
- UART2 - RS232
- UART4 - RS485
- MUX selection GPIO3_20 must be held high
- RE/DE for RS485 controlled with GPIO3_25

1 x RS232 with flow control:
- UART2 - RS232
- MUX selection GPIO3_20 must be held low
Signed-off-by: Parthiban Nallathambi <parthiban@linumiz.com>
Signed-off-by: Shawn Guo <shawnguo@kernel.org>

arch/arm64/boot/dts/freescale/Makefile

@@ -266,6 +266,14 @@ dtb-$(CONFIG_ARCH_MXC) += imx8mm-venice-gw73xx-0x-rs485.dtb
 dtb-$(CONFIG_ARCH_MXC) += imx8mp-venice-gw74xx-imx219.dtb
 dtb-$(CONFIG_ARCH_MXC) += imx8mp-venice-gw74xx-rpidsi.dtb
 
+imx8mm-phygate-tauri-l-rs232-rs232-dtbs		:= imx8mm-phygate-tauri-l.dtb imx8mm-phygate-tauri-l-rs232-rs232.dtbo
+imx8mm-phygate-tauri-l-rs232-cts-rts-dtbs	:= imx8mm-phygate-tauri-l.dtb imx8mm-phygate-tauri-l-rs232-rts-cts.dtbo
+imx8mm-phygate-tauri-l-rs232-rs485-dtbs		:= imx8mm-phygate-tauri-l.dtb imx8mm-phygate-tauri-l-rs232-rs485.dtbo
+
+dtb-$(CONFIG_ARCH_MXC) += imx8mm-phygate-tauri-l-rs232-rs232.dtb
+dtb-$(CONFIG_ARCH_MXC) += imx8mm-phygate-tauri-l-rs232-cts-rts.dtb
+dtb-$(CONFIG_ARCH_MXC) += imx8mm-phygate-tauri-l-rs232-rs485.dtb
+
 dtb-$(CONFIG_ARCH_S32) += s32g274a-evb.dtb
 dtb-$(CONFIG_ARCH_S32) += s32g274a-rdb2.dtb
 dtb-$(CONFIG_ARCH_S32) += s32g399a-rdb3.dtb

arch/arm64/boot/dts/freescale/imx8mm-phygate-tauri-l-rs232-rs232.dtso

+// SPDX-License-Identifier: (GPL-2.0+ OR MIT)
+/*
+ * Copyright (C) 2021 PHYTEC Messtechnik GmbH
+ * Author: Jens Lang <j.lang@phytec.de>
+ *
+ * Tauri-L 2 x RS232:
+ *  - GPIO3_20 uart4_rs485_en needs to be driven low (inactive)
+ */
+
+#include <dt-bindings/clock/imx8mm-clock.h>
+#include <dt-bindings/gpio/gpio.h>
+#include "imx8mm-pinfunc.h"
+
+/dts-v1/;
+/plugin/;
+
+&{/} {
+	compatible = "phytec,imx8mm-phygate-tauri-l";
+
+};
+
+&gpio3 {
+	pinctrl-names = "default";
+	pinctrcl-0 = <&pinctrl_gpio3_hog>;
+
+	uart4_rs485_en {
+		gpio-hog;
+		gpios = <20 GPIO_ACTIVE_HIGH>;
+		output-low;
+		line-name = "uart4_rs485_en";
+	};
+};
+
+/* UART2 - RS232  */
+&uart2 {
+	pinctrl-names = "default";
+	pinctrl-0 = <&pinctrl_uart2>;
+	assigned-clocks = <&clk IMX8MM_CLK_UART2>;
+	assigned-clock-parents = <&clk IMX8MM_SYS_PLL1_80M>;
+	status = "okay";
+};
+
+/* UART4 - RS232  */
+&uart4 {
+	pinctrl-names = "default";
+	pinctrl-0 = <&pinctrl_uart4>;
+	assigned-clocks = <&clk IMX8MM_CLK_UART4>;
+	assigned-clock-parents = <&clk IMX8MM_SYS_PLL1_80M>;
+	status = "okay";
+};
+
+&iomuxc {
+	pinctrl_gpio3_hog: gpio3hoggrp {
+		fsl,pins = <
+			MX8MM_IOMUXC_SAI5_RXC_GPIO3_IO20	0x49
+		>;
+	};
+
+	pinctrl_uart2: uart2grp {
+		fsl,pins = <
+			MX8MM_IOMUXC_UART2_RXD_UART2_DCE_RX	0x00
+			MX8MM_IOMUXC_UART2_TXD_UART2_DCE_TX	0x00
+		>;
+	};
+
+	pinctrl_uart4: uart4grp {
+		fsl,pins = <
+			MX8MM_IOMUXC_UART4_RXD_UART4_DCE_RX	0x49
+			MX8MM_IOMUXC_UART4_TXD_UART4_DCE_TX	0x49
+		>;
+	};
+};

arch/arm64/boot/dts/freescale/imx8mm-phygate-tauri-l-rs232-rs485.dtso

+// SPDX-License-Identifier: (GPL-2.0+ OR MIT)
+/*
+ * Copyright (C) 2021 PHYTEC Messtechnik GmbH
+ * Author: Jens Lang <j.lang@phytec.de>
+ *
+ * Tauri-L RS232 + RS485:
+ *  - GPIO3_20 uart4_rs485_en needs to be driven high (active)
+ *  - GPIO3_25 RS485_DE Driver enable
+ */
+
+#include <dt-bindings/clock/imx8mm-clock.h>
+#include <dt-bindings/gpio/gpio.h>
+#include "imx8mm-pinfunc.h"
+
+/dts-v1/;
+/plugin/;
+
+&{/} {
+	compatible = "phytec,imx8mm-phygate-tauri-l";
+
+};
+
+&gpio3 {
+	pinctrl-names = "default";
+	pinctrcl-0 = <&pinctrl_gpio3_hog>;
+
+	uart4_rs485_en {
+		gpio-hog;
+		gpios = <20 GPIO_ACTIVE_HIGH>;
+		output-high;
+		line-name = "uart4_rs485_en";
+	};
+};
+
+/* UART2 - RS232  */
+&uart2 {
+	pinctrl-names = "default";
+	pinctrl-0 = <&pinctrl_uart2>;
+	assigned-clocks = <&clk IMX8MM_CLK_UART2>;
+	assigned-clock-parents = <&clk IMX8MM_SYS_PLL1_80M>;
+	status = "okay";
+};
+
+/* UART4 - RS485  */
+&uart4 {
+	pinctrl-names = "default";
+	pinctrl-0 = <&pinctrl_uart4>;
+	assigned-clocks = <&clk IMX8MM_CLK_UART4>;
+	assigned-clock-parents = <&clk IMX8MM_SYS_PLL1_80M>;
+	rts-gpios = <&gpio3 25 GPIO_ACTIVE_HIGH>;
+	linux,rs485-enabled-at-boot-time;
+	status = "okay";
+};
+
+&iomuxc {
+	pinctrl_gpio3_hog: gpio3hoggrp {
+		fsl,pins = <
+			MX8MM_IOMUXC_SAI5_RXC_GPIO3_IO20	0x49
+		>;
+	};
+
+	pinctrl_uart2: uart2grp {
+		fsl,pins = <
+			MX8MM_IOMUXC_UART2_RXD_UART2_DCE_RX	0x00
+			MX8MM_IOMUXC_UART2_TXD_UART2_DCE_TX	0x00
+		>;
+	};
+
+	pinctrl_uart4: uart4grp {
+		fsl,pins = <
+			MX8MM_IOMUXC_UART4_RXD_UART4_DCE_RX	0x49
+			MX8MM_IOMUXC_UART4_TXD_UART4_DCE_TX	0x49
+			MX8MM_IOMUXC_SAI5_MCLK_GPIO3_IO25	0x49
+		>;
+	};
+};

arch/arm64/boot/dts/freescale/imx8mm-phygate-tauri-l-rs232-rts-cts.dtso

+// SPDX-License-Identifier: (GPL-2.0+ OR MIT)
+/*
+ * Copyright (C) 2023 PHYTEC Messtechnik GmbH
+ * Author: Jens Lang <j.lang@phytec.de>
+ *
+ * Tauri-L RS232 with RTS/CTS hardware flow control:
+ *  - UART4_TX becomes RTS
+ *  - UART4_RX becomes CTS
+ */
+
+#include <dt-bindings/clock/imx8mm-clock.h>
+#include "imx8mm-pinfunc.h"
+
+/dts-v1/;
+/plugin/;
+
+
+&{/} {
+	compatible = "phytec,imx8mm-phygate-tauri-l";
+
+};
+
+&uart2 {
+	pinctrl-names = "default";
+	pinctrl-0 = <&pinctrl_uart2>;
+	assigned-clocks = <&clk IMX8MM_CLK_UART2>;
+	assigned-clock-parents = <&clk IMX8MM_SYS_PLL1_80M>;
+	uart-has-rtscts;
+	status = "okay";
+};
+
+&iomuxc {
+	pinctrl_uart2: uart2grp {
+		fsl,pins = <
+			MX8MM_IOMUXC_UART2_RXD_UART2_DCE_RX	0x00
+			MX8MM_IOMUXC_UART2_TXD_UART2_DCE_TX	0x00
+			MX8MM_IOMUXC_UART4_RXD_UART2_DCE_CTS_B	0x00
+			MX8MM_IOMUXC_UART4_TXD_UART2_DCE_RTS_B	0x00
+		>;
+	};
+};