drivers: uart: adds pinctrl support for Arm cmsdk uart driver

Adds necessary pinctrl support for Arm cmsdk uart driver

Signed-off-by: Samuel Chee <samche01@arm.com>
Signed-off-by: Sudan Landge <sudan.landge@arm.com>

drivers/serial/Kconfig.cmsdk_apb

@@ -9,5 +9,6 @@ config UART_CMSDK_APB
 	depends on DT_HAS_ARM_CMSDK_UART_ENABLED
 	select SERIAL_HAS_DRIVER
 	select SERIAL_SUPPORT_INTERRUPT
+	select PINCTRL
 	help
 	  This option enables the UART driver for ARM CMSDK APB UART.

drivers/serial/uart_cmsdk_apb.c

@@ -1,5 +1,6 @@
 /*
  * Copyright (c) 2021, Linaro Limited.
+ * Copyright 2025 Arm Limited and/or its affiliates <open-source-office@arm.com>
  *
  * SPDX-License-Identifier: Apache-2.0
  */
@@ -15,6 +16,7 @@
 #include <zephyr/kernel.h>
 #include <zephyr/arch/cpu.h>
 #include <zephyr/drivers/clock_control/arm_clock_control.h>
+#include <zephyr/drivers/pinctrl.h>
 #include <zephyr/sys/__assert.h>
 #include <zephyr/init.h>
 #include <zephyr/drivers/uart.h>
@@ -64,6 +66,7 @@ struct uart_cmsdk_apb {
 struct uart_cmsdk_apb_config {
 	volatile struct uart_cmsdk_apb *uart;
 	uint32_t sys_clk_freq;
+	const struct pinctrl_dev_config *pctrl;
 #ifdef CONFIG_UART_INTERRUPT_DRIVEN
 	uart_irq_config_func_t irq_config_func;
 #endif
@@ -124,6 +127,14 @@ static void baudrate_set(const struct device *dev)
 static int uart_cmsdk_apb_init(const struct device *dev)
 {
 	const struct uart_cmsdk_apb_config * const dev_cfg = dev->config;
+	int ret = pinctrl_apply_state(dev_cfg->pctrl, PINCTRL_STATE_DEFAULT);
+
+	/* some pins are not available externally so,
+	 * ignore if there is no entry for them
+	 */
+	if (ret != -ENOENT) {
+		return ret;
+	}
 
 #ifdef CONFIG_CLOCK_CONTROL
 	/* Enable clock for subsystem */
@@ -478,10 +489,11 @@ static DEVICE_API(uart, uart_cmsdk_apb_driver_api) = {
 #ifdef CONFIG_UART_INTERRUPT_DRIVEN
 static void uart_cmsdk_apb_irq_config_func_0(const struct device *dev);
 #endif
-
+PINCTRL_DT_INST_DEFINE(0);
 static const struct uart_cmsdk_apb_config uart_cmsdk_apb_dev_cfg_0 = {
 	.uart = (volatile struct uart_cmsdk_apb *)DT_INST_REG_ADDR(0),
 	.sys_clk_freq = DT_INST_PROP_BY_PHANDLE(0, clocks, clock_frequency),
+	.pctrl = PINCTRL_DT_INST_DEV_CONFIG_GET(0),
 #ifdef CONFIG_UART_INTERRUPT_DRIVEN
 	.irq_config_func = uart_cmsdk_apb_irq_config_func_0,
 #endif
@@ -543,10 +555,11 @@ static void uart_cmsdk_apb_irq_config_func_0(const struct device *dev)
 #ifdef CONFIG_UART_INTERRUPT_DRIVEN
 static void uart_cmsdk_apb_irq_config_func_1(const struct device *dev);
 #endif
-
+PINCTRL_DT_INST_DEFINE(1);
 static const struct uart_cmsdk_apb_config uart_cmsdk_apb_dev_cfg_1 = {
 	.uart = (volatile struct uart_cmsdk_apb *)DT_INST_REG_ADDR(1),
 	.sys_clk_freq = DT_INST_PROP_BY_PHANDLE(1, clocks, clock_frequency),
+	.pctrl = PINCTRL_DT_INST_DEV_CONFIG_GET(1),
 #ifdef CONFIG_UART_INTERRUPT_DRIVEN
 	.irq_config_func = uart_cmsdk_apb_irq_config_func_1,
 #endif
@@ -608,10 +621,11 @@ static void uart_cmsdk_apb_irq_config_func_1(const struct device *dev)
 #ifdef CONFIG_UART_INTERRUPT_DRIVEN
 static void uart_cmsdk_apb_irq_config_func_2(const struct device *dev);
 #endif
-
+PINCTRL_DT_INST_DEFINE(2);
 static const struct uart_cmsdk_apb_config uart_cmsdk_apb_dev_cfg_2 = {
 	.uart = (volatile struct uart_cmsdk_apb *)DT_INST_REG_ADDR(2),
 	.sys_clk_freq = DT_INST_PROP_BY_PHANDLE(2, clocks, clock_frequency),
+	.pctrl = PINCTRL_DT_INST_DEV_CONFIG_GET(2),
 #ifdef CONFIG_UART_INTERRUPT_DRIVEN
 	.irq_config_func = uart_cmsdk_apb_irq_config_func_2,
 #endif
@@ -673,10 +687,11 @@ static void uart_cmsdk_apb_irq_config_func_2(const struct device *dev)
 #ifdef CONFIG_UART_INTERRUPT_DRIVEN
 static void uart_cmsdk_apb_irq_config_func_3(const struct device *dev);
 #endif
-
+PINCTRL_DT_INST_DEFINE(3);
 static const struct uart_cmsdk_apb_config uart_cmsdk_apb_dev_cfg_3 = {
 	.uart = (volatile struct uart_cmsdk_apb *)DT_INST_REG_ADDR(3),
 	.sys_clk_freq = DT_INST_PROP_BY_PHANDLE(3, clocks, clock_frequency),
+	.pctrl = PINCTRL_DT_INST_DEV_CONFIG_GET(3),
 #ifdef CONFIG_UART_INTERRUPT_DRIVEN
 	.irq_config_func = uart_cmsdk_apb_irq_config_func_3,
 #endif
@@ -734,14 +749,14 @@ static void uart_cmsdk_apb_irq_config_func_3(const struct device *dev)
 #endif /* DT_NODE_HAS_STATUS_OKAY(DT_DRV_INST(3)) */
 
 #if DT_NODE_HAS_STATUS_OKAY(DT_DRV_INST(4))
-
 #ifdef CONFIG_UART_INTERRUPT_DRIVEN
 static void uart_cmsdk_apb_irq_config_func_4(const struct device *dev);
 #endif
-
+PINCTRL_DT_INST_DEFINE(4);
 static const struct uart_cmsdk_apb_config uart_cmsdk_apb_dev_cfg_4 = {
 	.uart = (volatile struct uart_cmsdk_apb *)DT_INST_REG_ADDR(4),
 	.sys_clk_freq = DT_INST_PROP_BY_PHANDLE(4, clocks, clock_frequency),
+	.pctrl = PINCTRL_DT_INST_DEV_CONFIG_GET(4),
 #ifdef CONFIG_UART_INTERRUPT_DRIVEN
 	.irq_config_func = uart_cmsdk_apb_irq_config_func_4,
 #endif

dts/bindings/serial/arm,cmsdk-uart.yaml

@@ -2,7 +2,7 @@ description: ARM CMSDK UART
 
 compatible: "arm,cmsdk-uart"
 
-include: uart-controller.yaml
+include: [uart-controller.yaml, pinctrl-device.yaml]
 
 properties:
   reg: