drivers: serial: Add USART support for GD32V

Modifying configuration to enable with gd32vf103

- Add usart definition to devicetree.
- Define USART_STAT as alias of USART_STAT0 if not defined it.
- Enable USART if SOC_SERIES_RISCV_GIGADEVICE_GD32VF103.

Signed-off-by: TOKITA Hiroshi <[email protected]>

Author: soburi

boards/riscv/longan_nano/longan_nano-pinctrl.dtsi

@@ -0,0 +1,14 @@
+/*
+ * Copyright (c) 2021, TOKITA Hiroshi
+ * SPDX-License-Identifier: Apache-2.0
+ */
+
+#include <dt-bindings/pinctrl/gd32vf103c(b-8)xx-pinctrl.h>
+
+&pinctrl {
+	usart0_default: usart0_default {
+		group1 {
+			pinmux = <USART0_TX_PA9_NORMP>, <USART0_RX_PA10_NORMP>;
+		};
+	};
+};

boards/riscv/longan_nano/longan_nano.dts

@@ -6,13 +6,23 @@
 
 /dts-v1/;
 #include <gigadevice/gd32vf103Xb.dtsi>
+#include "longan_nano-pinctrl.dtsi"
 
 / {
 	model = "Sipeed Longan Nano";
 	compatible = "sipeed,longan_nano";
 
 	chosen {
+		zephyr,console = &usart0;
+		zephyr,shell-uart = &usart0;
 		zephyr,sram = &sram0;
 		zephyr,flash = &flash0;
 	};
 };
+
+&usart0 {
+	status = "okay";
+	current-speed = <115200>;
+	pinctrl-0 = <&usart0_default>;
+	pinctrl-names = "default";
+};

boards/riscv/longan_nano/longan_nano_defconfig

@@ -11,3 +11,11 @@ CONFIG_GD32_HXTAL_8MHZ=y
 
 # enable machine timer
 CONFIG_RISCV_MACHINE_TIMER=y
+
+# enable uart driver
+CONFIG_SERIAL=y
+CONFIG_UART_INTERRUPT_DRIVEN=y
+
+# enable console
+CONFIG_CONSOLE=y
+CONFIG_UART_CONSOLE=y

boards/riscv/longan_nano/longan_nano_lite.dts

@@ -6,13 +6,23 @@
 
 /dts-v1/;
 #include <gigadevice/gd32vf103X8.dtsi>
+#include "longan_nano-pinctrl.dtsi"
 
 / {
 	model = "Sipeed Longan Nano Lite";
 	compatible = "sipeed,longan_nano_lite";
 
 	chosen {
+		zephyr,console = &usart0;
+		zephyr,shell-uart = &usart0;
 		zephyr,sram = &sram0;
 		zephyr,flash = &flash0;
 	};
 };
+
+&usart0 {
+	status = "okay";
+	current-speed = <115200>;
+	pinctrl-0 = <&usart0_default>;
+	pinctrl-names = "default";
+};

boards/riscv/longan_nano/longan_nano_lite_defconfig

@@ -11,3 +11,11 @@ CONFIG_GD32_HXTAL_8MHZ=y
 
 # enable machine timer
 CONFIG_RISCV_MACHINE_TIMER=y
+
+# enable uart driver
+CONFIG_SERIAL=y
+CONFIG_UART_INTERRUPT_DRIVEN=y
+
+# enable console
+CONFIG_CONSOLE=y
+CONFIG_UART_CONSOLE=y

drivers/serial/Kconfig.gd32

@@ -7,7 +7,7 @@ DT_COMPAT_GIGADEVICE_GD32_USART := gd,gd32-usart
 config USART_GD32
 	bool "GD32 serial driver"
 	default $(dt_compat_enabled,$(DT_COMPAT_GIGADEVICE_GD32_USART))
-	depends on SOC_FAMILY_GD32
+	depends on (SOC_FAMILY_GD32 || SOC_SERIES_GD32VF103)
 	select SERIAL_HAS_DRIVER
 	select SERIAL_SUPPORT_INTERRUPT
 	select USE_GD32_USART

dts/riscv/gigadevice/gd32vf103.dtsi

@@ -65,6 +65,36 @@
 			};
 		};
 
+		usart0: serial@40013800 {
+			compatible = "gd,gd32-usart";
+			reg = <0x40013800 0x400>;
+			interrupts = <56 0>;
+			interrupt-parent = <&eclic>;
+			rcu-periph-clock = <0x60e>;
+			status = "disabled";
+			label = "UART_0";
+		};
+
+		usart1: serial@40004400 {
+			compatible = "gd,gd32-usart";
+			reg = <0x40004400 0x400>;
+			interrupts = <57 0>;
+			interrupt-parent = <&eclic>;
+			rcu-periph-clock = <0x711>;
+			status = "disabled";
+			label = "UART_1";
+		};
+
+		usart2: serial@40004800 {
+			compatible = "gd,gd32-usart";
+			reg = <0x40004800 0x400>;
+			interrupts = <58 0>;
+			interrupt-parent = <&eclic>;
+			rcu-periph-clock = <0x712>;
+			status = "disabled";
+			label = "UART_2";
+		};
+
 		afio: afio@40010000 {
 			compatible = "gd,gd32-afio";
 			reg = <0x40010000 0x400>;