[PATCH] arm64: dts: imx8mm-venice-gw72xx-0x: add dt overlays for serial modes

From: Tim Harvey
Date: Fri Jan 21 2022 - 13:38:00 EST

The imx8mm-venice-gw72xx-0x som+baseboard combination has a multi-protocol
RS-232/RS-485/RS-422 transceiver to an off-board connector which
can be configured in a number of ways via UART and GPIO configuration.

The default configuration per the imx8mm-venice-gw72xx-0x dts is for
UART2 TX/RX and UART4 TX/RX to be available as RS-232:
J15.1 UART2 TX out
J15.2 UART2 RX in
J15.3 UART4 TX out
J15.4 UART4 RX in
J15.5 GND

Add dt overlays to allow additional the modes of operation:

rs232-rts (UART2 RS-232 with RTS/CTS hardware flow control)
J15.1 TX out
J15.2 RX in
J15.3 RTS out
J15.4 CTS in
J15.5 GND

rs485 (UART2 RS-485 half duplex)
J15.1 TXRX-
J15.2 N/C
J15.3 TXRX+
J15.4 N/C
J15.5 GND

rs422 (UART2 RS-422 full duplex)
J15.1 TX-
J15.2 RX+
J15.3 TX+
J15.4 RX-
J15.5 GND

Signed-off-by: Tim Harvey <tharvey@xxxxxxxxxxxxx>
---
arch/arm64/boot/dts/freescale/Makefile | 3 +
.../imx8mm-venice-gw72xx-0x-rs232-rts.dts | 53 ++++++++++++++++
.../imx8mm-venice-gw72xx-0x-rs422.dts | 61 +++++++++++++++++++
.../imx8mm-venice-gw72xx-0x-rs485.dts | 61 +++++++++++++++++++
4 files changed, 178 insertions(+)
create mode 100644 arch/arm64/boot/dts/freescale/imx8mm-venice-gw72xx-0x-rs232-rts.dts
create mode 100644 arch/arm64/boot/dts/freescale/imx8mm-venice-gw72xx-0x-rs422.dts
create mode 100644 arch/arm64/boot/dts/freescale/imx8mm-venice-gw72xx-0x-rs485.dts

diff --git a/arch/arm64/boot/dts/freescale/Makefile b/arch/arm64/boot/dts/freescale/Makefile
index 5ec8d59347b6..2d3489eb073d 100644
--- a/arch/arm64/boot/dts/freescale/Makefile
+++ b/arch/arm64/boot/dts/freescale/Makefile
@@ -43,6 +43,9 @@ dtb-$(CONFIG_ARCH_MXC) += imx8mm-nitrogen-r2.dtb
dtb-$(CONFIG_ARCH_MXC) += imx8mm-var-som-symphony.dtb
dtb-$(CONFIG_ARCH_MXC) += imx8mm-venice-gw71xx-0x.dtb
dtb-$(CONFIG_ARCH_MXC) += imx8mm-venice-gw72xx-0x.dtb
+dtb-$(CONFIG_ARCH_MXC) += imx8mm-venice-gw72xx-0x-rs232-rts.dtbo
+dtb-$(CONFIG_ARCH_MXC) += imx8mm-venice-gw72xx-0x-rs422.dtbo
+dtb-$(CONFIG_ARCH_MXC) += imx8mm-venice-gw72xx-0x-rs485.dtbo
dtb-$(CONFIG_ARCH_MXC) += imx8mm-venice-gw73xx-0x.dtb
dtb-$(CONFIG_ARCH_MXC) += imx8mm-venice-gw73xx-0x-rs232-rts.dtbo
dtb-$(CONFIG_ARCH_MXC) += imx8mm-venice-gw73xx-0x-rs422.dtbo
diff --git a/arch/arm64/boot/dts/freescale/imx8mm-venice-gw72xx-0x-rs232-rts.dts b/arch/arm64/boot/dts/freescale/imx8mm-venice-gw72xx-0x-rs232-rts.dts
new file mode 100644
index 000000000000..3ea73a6886ff
--- /dev/null
+++ b/arch/arm64/boot/dts/freescale/imx8mm-venice-gw72xx-0x-rs232-rts.dts
@@ -0,0 +1,53 @@
+// SPDX-License-Identifier: (GPL-2.0+ OR MIT)
+/*
+ * Copyright 2022 Gateworks Corporation
+ *
+ * GW72xx RS232 with RTS/CTS hardware flow control:
+ * - GPIO4_0 rs485_en needs to be driven low (in-active)
+ * - UART4_TX becomes RTS
+ * - UART4_RX becomes CTS
+ */
+
+#include <dt-bindings/gpio/gpio.h>
+
+#include "imx8mm-pinfunc.h"
+
+/dts-v1/;
+/plugin/;
+
+&{/} {
+ compatible = "gw,imx8mm-gw72xx-0x";
+};
+
+&gpio4 {
+ rs485_en {
+ gpio-hog;
+ gpios = <0 GPIO_ACTIVE_HIGH>;
+ output-low;
+ line-name = "rs485_en";
+ };
+};
+
+&uart2 {
+ pinctrl-names = "default";
+ pinctrl-0 = <&pinctrl_uart2>;
+ rts-gpios = <&gpio5 29 GPIO_ACTIVE_LOW>;
+ cts-gpios = <&gpio5 28 GPIO_ACTIVE_LOW>;
+ uart-has-rtscts;
+ status = "okay";
+};
+
+&uart4 {
+ status = "disabled";
+};
+
+&iomuxc {
+ pinctrl_uart2: uart2grp {
+ fsl,pins = <
+ MX8MM_IOMUXC_UART2_RXD_UART2_DCE_RX 0x140
+ MX8MM_IOMUXC_UART2_TXD_UART2_DCE_TX 0x140
+ MX8MM_IOMUXC_UART4_TXD_GPIO5_IO29 0x140
+ MX8MM_IOMUXC_UART4_RXD_GPIO5_IO28 0x140
+ >;
+ };
+};
diff --git a/arch/arm64/boot/dts/freescale/imx8mm-venice-gw72xx-0x-rs422.dts b/arch/arm64/boot/dts/freescale/imx8mm-venice-gw72xx-0x-rs422.dts
new file mode 100644
index 000000000000..c3cd9f2b0db3
--- /dev/null
+++ b/arch/arm64/boot/dts/freescale/imx8mm-venice-gw72xx-0x-rs422.dts
@@ -0,0 +1,61 @@
+// SPDX-License-Identifier: (GPL-2.0+ OR MIT)
+/*
+ * Copyright 2022 Gateworks Corporation
+ *
+ * GW72xx RS422 (RS485 full duplex):
+ * - GPIO1_0 rs485_term selects on-chip termination
+ * - GPIO4_0 rs485_en needs to be driven high (active)
+ * - GPIO4_2 rs485_hd needs to be driven low (in-active)
+ * - UART4_TX is DE for RS485 transmitter
+ * - RS485_EN needs to be pulled high
+ * - RS485_HALF needs to be low
+ */
+
+#include <dt-bindings/gpio/gpio.h>
+
+#include "imx8mm-pinfunc.h"
+
+/dts-v1/;
+/plugin/;
+
+&{/} {
+ compatible = "gw,imx8mm-gw72xx-0x";
+};
+
+&gpio4 {
+ rs485_en {
+ gpio-hog;
+ gpios = <0 GPIO_ACTIVE_HIGH>;
+ output-high;
+ line-name = "rs485_en";
+ };
+
+ rs485_hd {
+ gpio-hog;
+ gpios = <2 GPIO_ACTIVE_HIGH>;
+ output-low;
+ line-name = "rs485_hd";
+ };
+};
+
+&uart2 {
+ pinctrl-names = "default";
+ pinctrl-0 = <&pinctrl_uart2>;
+ rts-gpios = <&gpio5 29 GPIO_ACTIVE_HIGH>;
+ linux,rs485-enabled-at-boot-time;
+ status = "okay";
+};
+
+&uart4 {
+ status = "disabled";
+};
+
+&iomuxc {
+ pinctrl_uart2: uart2grp {
+ fsl,pins = <
+ MX8MM_IOMUXC_UART2_RXD_UART2_DCE_RX 0x140
+ MX8MM_IOMUXC_UART2_TXD_UART2_DCE_TX 0x140
+ MX8MM_IOMUXC_UART4_TXD_GPIO5_IO29 0x140
+ >;
+ };
+};
diff --git a/arch/arm64/boot/dts/freescale/imx8mm-venice-gw72xx-0x-rs485.dts b/arch/arm64/boot/dts/freescale/imx8mm-venice-gw72xx-0x-rs485.dts
new file mode 100644
index 000000000000..cc0a287226ab
--- /dev/null
+++ b/arch/arm64/boot/dts/freescale/imx8mm-venice-gw72xx-0x-rs485.dts
@@ -0,0 +1,61 @@
+// SPDX-License-Identifier: (GPL-2.0+ OR MIT)
+/*
+ * Copyright 2022 Gateworks Corporation
+ *
+ * GW72xx RS485 HD:
+ * - GPIO1_0 rs485_term selects on-chip termination
+ * - GPIO4_0 rs485_en needs to be driven high (active)
+ * - GPIO4_2 rs485_hd needs to be driven high (active)
+ * - UART4_TX is DE for RS485 transmitter
+ * - RS485_EN needs to be pulled high
+ * - RS485_HALF needs to be pulled high
+ */
+
+#include <dt-bindings/gpio/gpio.h>
+
+#include "imx8mm-pinfunc.h"
+
+/dts-v1/;
+/plugin/;
+
+&{/} {
+ compatible = "gw,imx8mm-gw72xx-0x";
+};
+
+&gpio4 {
+ rs485_en {
+ gpio-hog;
+ gpios = <0 GPIO_ACTIVE_HIGH>;
+ output-high;
+ line-name = "rs485_en";
+ };
+
+ rs485_hd {
+ gpio-hog;
+ gpios = <2 GPIO_ACTIVE_HIGH>;
+ output-high;
+ line-name = "rs485_hd";
+ };
+};
+
+&uart2 {
+ pinctrl-names = "default";
+ pinctrl-0 = <&pinctrl_uart2>;
+ rts-gpios = <&gpio5 29 GPIO_ACTIVE_HIGH>;
+ linux,rs485-enabled-at-boot-time;
+ status = "okay";
+};
+
+&uart4 {
+ status = "disabled";
+};
+
+&iomuxc {
+ pinctrl_uart2: uart2grp {
+ fsl,pins = <
+ MX8MM_IOMUXC_UART2_RXD_UART2_DCE_RX 0x140
+ MX8MM_IOMUXC_UART2_TXD_UART2_DCE_TX 0x140
+ MX8MM_IOMUXC_UART4_TXD_GPIO5_IO29 0x140
+ >;
+ };
+};
--
2.17.1