drivers/serial/uart_rzt2m.c - third_party/github/zephyrproject-rtos/zephyr - Git at Google

 /*
  * Copyright (c) 2023 Antmicro <www.antmicro.com>
  *
  * SPDX-License-Identifier: Apache-2.0
  */

 #include "uart_rzt2m.h"
 #include "zephyr/spinlock.h"
 #include "zephyr/sys/printk.h"
 #include <zephyr/drivers/uart.h>
 #include <zephyr/drivers/pinctrl.h>
 #include <zephyr/sys/util.h>
 #include <zephyr/irq.h>
 #include <stdint.h>
 #include <zephyr/logging/log.h>
 #include <soc.h>

 #define DT_DRV_COMPAT renesas_rzt2m_uart

 LOG_MODULE_REGISTER(uart_renesas_rzt2m, CONFIG_UART_LOG_LEVEL);

 struct rzt2m_device_config {
 	mm_reg_t base;
 	const struct pinctrl_dev_config *pin_config;
 	uart_irq_config_func_t irq_config_func;
 };

 struct rzt2m_device_data {
 	struct uart_config uart_cfg;
 	struct k_spinlock lock;
 #ifdef CONFIG_UART_INTERRUPT_DRIVEN
 	uart_irq_callback_user_data_t callback;
 	void *callback_data;
 #endif
 };

 static int rzt2m_poll_in(const struct device *dev, unsigned char *c)
 {
 	if (!dev || !dev->config || !dev->data) {
 		return -ENODEV;
 	}

 	const struct rzt2m_device_config *config = dev->config;
 	struct rzt2m_device_data *data = dev->data;

 	k_spinlock_key_t key = k_spin_lock(&data->lock);

 	if (FRSR_R(*FRSR(config->base)) == 0) {
 		k_spin_unlock(&data->lock, key);
 		return -1;
 	}
 	*c = *RDR(config->base) & RDR_MASK_RDAT;
 	*CFCLR(config->base) |= CFCLR_MASK_RDRFC;

 	if (FRSR_R(*FRSR(config->base)) == 0) {
 		*FFCLR(config->base) |= FFCLR_MASK_DRC;
 	}

 	k_spin_unlock(&data->lock, key);
 	return 0;
 }

 static void rzt2m_poll_out(const struct device *dev, unsigned char c)
 {
 	if (!dev || !dev->config || !dev->data) {
 		return;
 	}

 	const struct rzt2m_device_config *config = dev->config;
 	struct rzt2m_device_data *data = dev->data;

 	k_spinlock_key_t key = k_spin_lock(&data->lock);

 	int fifo_count = FTSR_T(*FTSR(config->base));

 	while (fifo_count == MAX_FIFO_DEPTH) {
 		fifo_count = FTSR_T(*FTSR(config->base));
 	}

 	*TDR(config->base) = c;

 	/* Clear `Transmit data empty flag`. */
 	*CFCLR(config->base) |= CFCLR_MASK_TDREC;

 	k_spin_unlock(&data->lock, key);
 }

 static int rzt2m_err_check(const struct device *dev)
 {
 	const struct rzt2m_device_config *config = dev->config;

 	uint32_t status = *CSR(config->base);
 	uint32_t retval = 0;

 	if (status & CSR_MASK_ORER) {
 		retval |= UART_ERROR_OVERRUN;
 	}
 	if (status & CSR_MASK_FER) {
 		retval |= UART_ERROR_FRAMING;
 	}
 	if (status & CSR_MASK_PER) {
 		retval |= UART_ERROR_PARITY;
 	}

 	return retval;
 }

 #ifdef CONFIG_UART_INTERRUPT_DRIVEN
 static int uart_rzt2m_irq_tx_ready(const struct device *dev);

 static int rzt2m_fifo_fill(const struct device *dev, const uint8_t *tx_data, int size)
 {
 	struct rzt2m_device_data *data = dev->data;
 	const struct rzt2m_device_config *config = dev->config;
 	int num_tx = 0;
 	k_spinlock_key_t key = k_spin_lock(&data->lock);

 	while ((size - num_tx > 0) && uart_rzt2m_irq_tx_ready(dev)) {
 		*TDR(config->base) = (uint8_t)tx_data[num_tx++];
 	}

 	k_spin_unlock(&data->lock, key);
 	return num_tx;
 }

 static int rzt2m_fifo_read(const struct device *dev, uint8_t *rx_data, const int size)
 {
 	struct rzt2m_device_data *data = dev->data;
 	const struct rzt2m_device_config *config = dev->config;
 	int num_rx = 0;
 	k_spinlock_key_t key = k_spin_lock(&data->lock);

 	while (num_rx < size && (FRSR_R(*FRSR(config->base)))) {
 		rx_data[num_rx++] = *RDR(config->base);
 	}
 	*CFCLR(config->base) = CFCLR_MASK_RDRFC;
 	*FFCLR(config->base) = FFCLR_MASK_DRC;
 	k_spin_unlock(&data->lock, key);
 	return num_rx;
 }

 static void uart_rzt2m_irq_rx_enable(const struct device *dev)
 {
 	const struct rzt2m_device_config *config = dev->config;
 	*CCR0(config->base) |= CCR0_MASK_RIE | CCR0_MASK_RE;
 }

 static void uart_rzt2m_irq_rx_disable(const struct device *dev)
 {
 	const struct rzt2m_device_config *config = dev->config;
 	*CCR0(config->base) &= ~CCR0_MASK_RIE;
 }

 static void uart_rzt2m_irq_tx_enable(const struct device *dev)
 {
 	const struct rzt2m_device_config *config = dev->config;
 	/* These bits must be set simultaneously. */
 	*CCR0(config->base) |= CCR0_MASK_TE | CCR0_MASK_TIE | CCR0_MASK_TEIE;
 }

 static void uart_rzt2m_irq_tx_disable(const struct device *dev)
 {
 	const struct rzt2m_device_config *config = dev->config;
 	*CCR0(config->base) &= ~(CCR0_MASK_TIE | CCR0_MASK_TEIE);
 }

 static int uart_rzt2m_irq_tx_ready(const struct device *dev)
 {
 	const struct rzt2m_device_config *config = dev->config;

 	if (FTSR_T(*FTSR(config->base)) == MAX_FIFO_DEPTH ||
 	    ((*CCR0(config->base) & CCR0_MASK_TIE) == 0)) {
 		return 0;
 	}

 	return 1;
 }

 static int uart_rzt2m_irq_rx_ready(const struct device *dev)
 {
 	const struct rzt2m_device_config *config = dev->config;

 	if (FRSR_R(*FRSR(config->base))) {
 		return 1;
 	}

 	return 0;
 }

 static int uart_rzt2m_irq_is_pending(const struct device *dev)
 {
 	const struct rzt2m_device_config *config = dev->config;

 	if ((*CSR(config->base) & (CSR_MASK_RDRF)) || (*FRSR(config->base) & FRSR_MASK_DR)) {
 		return 1;
 	}
 	return 0;
 }

 static void uart_rzt2m_irq_callback_set(const struct device *dev, uart_irq_callback_user_data_t cb,
 					void *cb_data)
 {
 	struct rzt2m_device_data *data = dev->data;

 	data->callback = cb;
 	data->callback_data = cb_data;
 }

 static int uart_rzt2m_irq_update(const struct device *dev)
 {
 	const struct rzt2m_device_config *config = dev->config;

 	*CFCLR(config->base) = CFCLR_MASK_RDRFC;
 	*FFCLR(config->base) = FFCLR_MASK_DRC;
 	return 1;
 }
 #endif /* CONFIG_UART_INTERRUPT_DRIVEN */

 static DEVICE_API(uart, rzt2m_uart_api) = {
 	.poll_in = rzt2m_poll_in,
 	.poll_out = rzt2m_poll_out,
 	.err_check = rzt2m_err_check,
 #ifdef CONFIG_UART_INTERRUPT_DRIVEN
 	.fifo_fill = rzt2m_fifo_fill,
 	.fifo_read = rzt2m_fifo_read,
 	.irq_rx_enable = uart_rzt2m_irq_rx_enable,
 	.irq_rx_disable = uart_rzt2m_irq_rx_disable,
 	.irq_tx_enable = uart_rzt2m_irq_tx_enable,
 	.irq_tx_disable = uart_rzt2m_irq_tx_disable,
 	.irq_tx_ready = uart_rzt2m_irq_tx_ready,
 	.irq_rx_ready = uart_rzt2m_irq_rx_ready,
 	.irq_is_pending = uart_rzt2m_irq_is_pending,
 	.irq_callback_set = uart_rzt2m_irq_callback_set,
 	.irq_update = uart_rzt2m_irq_update,
 #endif /* CONFIG_UART_INTERRUPT_DRIVEN */
 };

 static int rzt2m_module_start(const struct device *dev)
 {
 	if (!dev || !dev->config || !dev->data) {
 		return -ENODEV;
 	}

 	const struct rzt2m_device_config *config = dev->config;
 	struct rzt2m_device_data *data = dev->data;
 	int interface_id = BASE_TO_IFACE_ID(config->base);
 	unsigned int irqkey = irq_lock();
 	volatile uint32_t dummy;

 	k_spinlock_key_t key = k_spin_lock(&data->lock);

 	if (interface_id < 5) {
 		/* Dummy-read at least one time as stated in 8.3.1 of the User's Manual: Hardware */
 		*MSTPCRA &= ~(MSTPCRA_MASK_SCIx(interface_id));
 		dummy = *MSTPCRA;
 	} else {
 		LOG_ERR("SCI modules in the secure domain on RZT2M are not supported.");
 		return -ENOTSUP;
 	}

 	/* Dummy-read at least five times as stated in 8.3.1 of the User's Manual: Hardware */
 	dummy = *RDR(config->base);
 	dummy = *RDR(config->base);
 	dummy = *RDR(config->base);
 	dummy = *RDR(config->base);
 	dummy = *RDR(config->base);

 	k_spin_unlock(&data->lock, key);
 	irq_unlock(irqkey);
 	return 0;
 }

 static int rzt2m_uart_init(const struct device *dev)
 {
 	const struct rzt2m_device_config *config = dev->config;
 	struct rzt2m_device_data *data = dev->data;
 	uint32_t baud_setting = 0;
 	uint32_t baud_settings[] = {CCR2_BAUD_SETTING_9600, CCR2_BAUD_SETTING_115200};

 	rzt2m_unlock_prcrs(PRCRS_GPIO);
 	rzt2m_unlock_prcrn(PRCRN_PRC1 | PRCRN_PRC2);

 	/* The module needs to be started
 	 * to allow any operation on the registers of Serial Communications Interface.
 	 */
 	int ret = rzt2m_module_start(dev);

 	if (ret) {
 		return ret;
 	}

 	/* Disable transmitter, receiver, interrupts. */
 	*CCR0(config->base) = CCR0_DEFAULT_VALUE;
 	while (*CCR0(config->base) & (CCR0_MASK_RE | CCR0_MASK_TE)) {
 	}

 	*CCR1(config->base) = CCR1_DEFAULT_VALUE;
 	*CCR2(config->base) = CCR2_DEFAULT_VALUE;
 	*CCR3(config->base) = CCR3_DEFAULT_VALUE;
 	*CCR4(config->base) = CCR4_DEFAULT_VALUE;

 	/* Configure pinmuxes */
 	ret = pinctrl_apply_state(config->pin_config, PINCTRL_STATE_DEFAULT);
 	if (ret) {
 		return ret;
 	}

 	*CFCLR(config->base) = CFCLR_ALL_FLAG_CLEAR;
 	*FFCLR(config->base) = FFCLR_MASK_DRC;

 	/* Use FIFO mode. */
 	*CCR3(config->base) |= (CCR3_MASK_FM);

 	switch (data->uart_cfg.stop_bits) {
 	case UART_CFG_STOP_BITS_1:
 		/* Default value, already set. */
 		break;
 	case UART_CFG_STOP_BITS_2:
 		*CCR3(config->base) |= CCR3_MASK_STP;
 		break;
 	default:
 		LOG_ERR("Selected bit stop length is not supported: %u.", data->uart_cfg.stop_bits);
 		return -ENOTSUP;
 	}

 	switch (data->uart_cfg.data_bits) {
 	case UART_CFG_DATA_BITS_7:
 		*CCR3(config->base) |= CCR3_CHR_7BIT;
 		break;
 	case UART_CFG_DATA_BITS_8:
 		*CCR3(config->base) |= CCR3_CHR_8BIT;
 		break;
 	default:
 		LOG_ERR("Selected number of data bits is not supported: %u.",
 			data->uart_cfg.data_bits);
 		return -ENOTSUP;
 	}

 	if (data->uart_cfg.baudrate > ARRAY_SIZE(baud_settings)) {
 		LOG_ERR("Selected baudrate variant is not supported: %u.", data->uart_cfg.baudrate);
 		return -ENOTSUP;
 	}
 	baud_setting = baud_settings[data->uart_cfg.baudrate];

 	*CCR2(config->base) &= ~(CCR2_MASK_BAUD_SETTING);
 	*CCR2(config->base) |= (baud_setting & CCR2_MASK_BAUD_SETTING);

 	*CCR1(config->base) |= (CCR1_MASK_NFEN | CCR1_MASK_SPB2DT | CCR1_MASK_SPB2IO);

 	switch (data->uart_cfg.parity) {
 	case UART_CFG_PARITY_NONE:
 		/* Default value, already set. */
 		break;
 	case UART_CFG_PARITY_EVEN:
 		*CCR1(config->base) |= CCR1_MASK_PE;
 		break;
 	case UART_CFG_PARITY_ODD:
 		*CCR1(config->base) |= (CCR1_MASK_PE | CCR1_MASK_PM);
 		break;
 	default:
 		LOG_ERR("Unsupported parity: %u", data->uart_cfg.parity);
 	}

 	/* Specify trigger thresholds and clear FIFOs. */
 	*FCR(config->base) = FCR_MASK_TFRST | FCR_MASK_RFRST | FCR_TTRG_15 | FCR_RTRG_15;

 	/* Enable the clock. */
 	*CCR3(config->base) &= ~CCR3_MASK_CKE;
 	*CCR3(config->base) |= CCR3_CKE_ENABLE;

 	/* Clear status flags. */
 	*CFCLR(config->base) = CFCLR_ALL_FLAG_CLEAR;
 	*FFCLR(config->base) = FFCLR_MASK_DRC;

 #ifdef CONFIG_UART_INTERRUPT_DRIVEN
 	config->irq_config_func(dev);
 #endif /* CONFIG_UART_INTERRUPT_DRIVEN */

 	/* Start transmitter and receiver. */
 	*CCR0(config->base) |= (CCR0_MASK_TE | CCR0_MASK_RE);
 	while (!(*CCR0(config->base) & CCR0_MASK_RE)) {
 	}
 	while (!(*CCR0(config->base) & CCR0_MASK_TE)) {
 	}

 	rzt2m_lock_prcrs(PRCRS_GPIO);
 	rzt2m_lock_prcrn(PRCRN_PRC1 | PRCRN_PRC2);

 	return 0;
 }

 static void uart_rzt2m_isr(const struct device *dev)
 {
 	const struct rzt2m_device_config *config = dev->config;
 #ifdef CONFIG_UART_INTERRUPT_DRIVEN
 	struct rzt2m_device_data *data = dev->data;

 	if (data->callback) {
 		data->callback(dev, data->callback_data);
 	}
 #endif /* CONFIG_UART_INTERRUPT_DRIVEN */

 	*CFCLR(config->base) = CFCLR_MASK_RDRFC;
 	*FFCLR(config->base) = FFCLR_MASK_DRC;
 }

 #define UART_RZT2M_IRQ_CONNECT(n, irq_name)                                                        \
 	do {                                                                                       \
 		IRQ_CONNECT(DT_INST_IRQ_BY_NAME(n, irq_name, irq),                                 \
 			    DT_INST_IRQ_BY_NAME(n, irq_name, priority), uart_rzt2m_isr,            \
 			    DEVICE_DT_INST_GET(n), DT_INST_IRQ_BY_NAME(n, irq_name, flags));       \
 		irq_enable(DT_INST_IRQ_BY_NAME(n, irq_name, irq));                                 \
 	} while (false)

 #define UART_RZT2M_CONFIG_FUNC(n)                                                                  \
 	static void uart##n##_rzt2m_irq_config(const struct device *port)                          \
 	{                                                                                          \
 		UART_RZT2M_IRQ_CONNECT(n, rx_err);                                                 \
 		UART_RZT2M_IRQ_CONNECT(n, rx);                                                     \
 		UART_RZT2M_IRQ_CONNECT(n, tx);                                                     \
 		UART_RZT2M_IRQ_CONNECT(n, tx_end);                                                 \
 	}

 #define UART_RZT2M_INIT(n)                                                                         \
 	PINCTRL_DT_INST_DEFINE(n);                                                                 \
 	static struct rzt2m_device_data rzt2m_uart_##n##data = {                                   \
 		.uart_cfg =                                                                        \
 			{                                                                          \
 				.baudrate = DT_INST_ENUM_IDX(n, current_speed),                    \
 				.parity = DT_INST_ENUM_IDX(n, parity),                             \
 				.stop_bits = DT_INST_ENUM_IDX(n, stop_bits),                       \
 				.data_bits = DT_INST_ENUM_IDX(n, data_bits),                       \
 			},                                                                         \
 	};                                                                                         \
 	UART_RZT2M_CONFIG_FUNC(n);                                                                 \
 	static const struct rzt2m_device_config rzt2m_uart_##n##_config = {                        \
 		.base = DT_INST_REG_ADDR(n),                                                       \
 		.irq_config_func = uart##n##_rzt2m_irq_config,                                     \
 		.pin_config = PINCTRL_DT_INST_DEV_CONFIG_GET(n)};                                  \
 	DEVICE_DT_INST_DEFINE(n, rzt2m_uart_init, NULL, &rzt2m_uart_##n##data,                     \
 			      &rzt2m_uart_##n##_config, PRE_KERNEL_1, CONFIG_SERIAL_INIT_PRIORITY, \
 			      &rzt2m_uart_api);

 DT_INST_FOREACH_STATUS_OKAY(UART_RZT2M_INIT)
	/*
	* Copyright (c) 2023 Antmicro <www.antmicro.com>
	*
	* SPDX-License-Identifier: Apache-2.0
	*/

	#include "uart_rzt2m.h"
	#include "zephyr/spinlock.h"
	#include "zephyr/sys/printk.h"
	#include <zephyr/drivers/uart.h>
	#include <zephyr/drivers/pinctrl.h>
	#include <zephyr/sys/util.h>
	#include <zephyr/irq.h>
	#include <stdint.h>
	#include <zephyr/logging/log.h>
	#include <soc.h>

	#define DT_DRV_COMPAT renesas_rzt2m_uart

	LOG_MODULE_REGISTER(uart_renesas_rzt2m, CONFIG_UART_LOG_LEVEL);

	struct rzt2m_device_config {
	mm_reg_t base;
	const struct pinctrl_dev_config *pin_config;
	uart_irq_config_func_t irq_config_func;
	};

	struct rzt2m_device_data {
	struct uart_config uart_cfg;
	struct k_spinlock lock;
	#ifdef CONFIG_UART_INTERRUPT_DRIVEN
	uart_irq_callback_user_data_t callback;
	void *callback_data;
	#endif
	};

	static int rzt2m_poll_in(const struct device dev, unsigned char c)
	{
	if (!dev \|\| !dev->config \|\| !dev->data) {
	return -ENODEV;
	}

	const struct rzt2m_device_config *config = dev->config;
	struct rzt2m_device_data *data = dev->data;

	k_spinlock_key_t key = k_spin_lock(&data->lock);

	if (FRSR_R(*FRSR(config->base)) == 0) {
	k_spin_unlock(&data->lock, key);
	return -1;
	}
	c = RDR(config->base) & RDR_MASK_RDAT;
	*CFCLR(config->base) \|= CFCLR_MASK_RDRFC;

	if (FRSR_R(*FRSR(config->base)) == 0) {
	*FFCLR(config->base) \|= FFCLR_MASK_DRC;
	}

	k_spin_unlock(&data->lock, key);
	return 0;
	}

	static void rzt2m_poll_out(const struct device *dev, unsigned char c)
	{
	if (!dev \|\| !dev->config \|\| !dev->data) {
	return;
	}

	const struct rzt2m_device_config *config = dev->config;
	struct rzt2m_device_data *data = dev->data;

	k_spinlock_key_t key = k_spin_lock(&data->lock);

	int fifo_count = FTSR_T(*FTSR(config->base));

	while (fifo_count == MAX_FIFO_DEPTH) {
	fifo_count = FTSR_T(*FTSR(config->base));
	}

	*TDR(config->base) = c;

	/* Clear `Transmit data empty flag`. */
	*CFCLR(config->base) \|= CFCLR_MASK_TDREC;

	k_spin_unlock(&data->lock, key);
	}

	static int rzt2m_err_check(const struct device *dev)
	{
	const struct rzt2m_device_config *config = dev->config;

	uint32_t status = *CSR(config->base);
	uint32_t retval = 0;

	if (status & CSR_MASK_ORER) {
	retval \|= UART_ERROR_OVERRUN;
	}
	if (status & CSR_MASK_FER) {
	retval \|= UART_ERROR_FRAMING;
	}
	if (status & CSR_MASK_PER) {
	retval \|= UART_ERROR_PARITY;
	}

	return retval;
	}

	#ifdef CONFIG_UART_INTERRUPT_DRIVEN
	static int uart_rzt2m_irq_tx_ready(const struct device *dev);

	static int rzt2m_fifo_fill(const struct device dev, const uint8_t tx_data, int size)
	{
	struct rzt2m_device_data *data = dev->data;
	const struct rzt2m_device_config *config = dev->config;
	int num_tx = 0;
	k_spinlock_key_t key = k_spin_lock(&data->lock);

	while ((size - num_tx > 0) && uart_rzt2m_irq_tx_ready(dev)) {
	*TDR(config->base) = (uint8_t)tx_data[num_tx++];
	}

	k_spin_unlock(&data->lock, key);
	return num_tx;
	}

	static int rzt2m_fifo_read(const struct device dev, uint8_t rx_data, const int size)
	{
	struct rzt2m_device_data *data = dev->data;
	const struct rzt2m_device_config *config = dev->config;
	int num_rx = 0;
	k_spinlock_key_t key = k_spin_lock(&data->lock);

	while (num_rx < size && (FRSR_R(*FRSR(config->base)))) {
	rx_data[num_rx++] = *RDR(config->base);
	}
	*CFCLR(config->base) = CFCLR_MASK_RDRFC;
	*FFCLR(config->base) = FFCLR_MASK_DRC;
	k_spin_unlock(&data->lock, key);
	return num_rx;
	}

	static void uart_rzt2m_irq_rx_enable(const struct device *dev)
	{
	const struct rzt2m_device_config *config = dev->config;
	*CCR0(config->base) \|= CCR0_MASK_RIE \| CCR0_MASK_RE;
	}

	static void uart_rzt2m_irq_rx_disable(const struct device *dev)
	{
	const struct rzt2m_device_config *config = dev->config;
	*CCR0(config->base) &= ~CCR0_MASK_RIE;
	}

	static void uart_rzt2m_irq_tx_enable(const struct device *dev)
	{
	const struct rzt2m_device_config *config = dev->config;
	/* These bits must be set simultaneously. */
	*CCR0(config->base) \|= CCR0_MASK_TE \| CCR0_MASK_TIE \| CCR0_MASK_TEIE;
	}

	static void uart_rzt2m_irq_tx_disable(const struct device *dev)
	{
	const struct rzt2m_device_config *config = dev->config;
	*CCR0(config->base) &= ~(CCR0_MASK_TIE \| CCR0_MASK_TEIE);
	}

	static int uart_rzt2m_irq_tx_ready(const struct device *dev)
	{
	const struct rzt2m_device_config *config = dev->config;

	if (FTSR_T(*FTSR(config->base)) == MAX_FIFO_DEPTH \|\|
	((*CCR0(config->base) & CCR0_MASK_TIE) == 0)) {
	return 0;
	}

	return 1;
	}

	static int uart_rzt2m_irq_rx_ready(const struct device *dev)
	{
	const struct rzt2m_device_config *config = dev->config;

	if (FRSR_R(*FRSR(config->base))) {
	return 1;
	}

	return 0;
	}

	static int uart_rzt2m_irq_is_pending(const struct device *dev)
	{
	const struct rzt2m_device_config *config = dev->config;

	if ((CSR(config->base) & (CSR_MASK_RDRF)) \|\| (FRSR(config->base) & FRSR_MASK_DR)) {
	return 1;
	}
	return 0;
	}

	static void uart_rzt2m_irq_callback_set(const struct device *dev, uart_irq_callback_user_data_t cb,
	void *cb_data)
	{
	struct rzt2m_device_data *data = dev->data;

	data->callback = cb;
	data->callback_data = cb_data;
	}

	static int uart_rzt2m_irq_update(const struct device *dev)
	{
	const struct rzt2m_device_config *config = dev->config;

	*CFCLR(config->base) = CFCLR_MASK_RDRFC;
	*FFCLR(config->base) = FFCLR_MASK_DRC;
	return 1;
	}
	#endif /* CONFIG_UART_INTERRUPT_DRIVEN */

	static DEVICE_API(uart, rzt2m_uart_api) = {
	.poll_in = rzt2m_poll_in,
	.poll_out = rzt2m_poll_out,
	.err_check = rzt2m_err_check,
	#ifdef CONFIG_UART_INTERRUPT_DRIVEN
	.fifo_fill = rzt2m_fifo_fill,
	.fifo_read = rzt2m_fifo_read,
	.irq_rx_enable = uart_rzt2m_irq_rx_enable,
	.irq_rx_disable = uart_rzt2m_irq_rx_disable,
	.irq_tx_enable = uart_rzt2m_irq_tx_enable,
	.irq_tx_disable = uart_rzt2m_irq_tx_disable,
	.irq_tx_ready = uart_rzt2m_irq_tx_ready,
	.irq_rx_ready = uart_rzt2m_irq_rx_ready,
	.irq_is_pending = uart_rzt2m_irq_is_pending,
	.irq_callback_set = uart_rzt2m_irq_callback_set,
	.irq_update = uart_rzt2m_irq_update,
	#endif /* CONFIG_UART_INTERRUPT_DRIVEN */
	};

	static int rzt2m_module_start(const struct device *dev)
	{
	if (!dev \|\| !dev->config \|\| !dev->data) {
	return -ENODEV;
	}

	const struct rzt2m_device_config *config = dev->config;
	struct rzt2m_device_data *data = dev->data;
	int interface_id = BASE_TO_IFACE_ID(config->base);
	unsigned int irqkey = irq_lock();
	volatile uint32_t dummy;

	k_spinlock_key_t key = k_spin_lock(&data->lock);

	if (interface_id < 5) {
	/* Dummy-read at least one time as stated in 8.3.1 of the User's Manual: Hardware */
	*MSTPCRA &= ~(MSTPCRA_MASK_SCIx(interface_id));
	dummy = *MSTPCRA;
	} else {
	LOG_ERR("SCI modules in the secure domain on RZT2M are not supported.");
	return -ENOTSUP;
	}

	/* Dummy-read at least five times as stated in 8.3.1 of the User's Manual: Hardware */
	dummy = *RDR(config->base);
	dummy = *RDR(config->base);
	dummy = *RDR(config->base);
	dummy = *RDR(config->base);
	dummy = *RDR(config->base);

	k_spin_unlock(&data->lock, key);
	irq_unlock(irqkey);
	return 0;
	}

	static int rzt2m_uart_init(const struct device *dev)
	{
	const struct rzt2m_device_config *config = dev->config;
	struct rzt2m_device_data *data = dev->data;
	uint32_t baud_setting = 0;
	uint32_t baud_settings[] = {CCR2_BAUD_SETTING_9600, CCR2_BAUD_SETTING_115200};

	rzt2m_unlock_prcrs(PRCRS_GPIO);
	rzt2m_unlock_prcrn(PRCRN_PRC1 \| PRCRN_PRC2);

	/* The module needs to be started
	* to allow any operation on the registers of Serial Communications Interface.
	*/
	int ret = rzt2m_module_start(dev);

	if (ret) {
	return ret;
	}

	/* Disable transmitter, receiver, interrupts. */
	*CCR0(config->base) = CCR0_DEFAULT_VALUE;
	while (*CCR0(config->base) & (CCR0_MASK_RE \| CCR0_MASK_TE)) {
	}

	*CCR1(config->base) = CCR1_DEFAULT_VALUE;
	*CCR2(config->base) = CCR2_DEFAULT_VALUE;
	*CCR3(config->base) = CCR3_DEFAULT_VALUE;
	*CCR4(config->base) = CCR4_DEFAULT_VALUE;

	/* Configure pinmuxes */
	ret = pinctrl_apply_state(config->pin_config, PINCTRL_STATE_DEFAULT);
	if (ret) {
	return ret;
	}

	*CFCLR(config->base) = CFCLR_ALL_FLAG_CLEAR;
	*FFCLR(config->base) = FFCLR_MASK_DRC;

	/* Use FIFO mode. */
	*CCR3(config->base) \|= (CCR3_MASK_FM);

	switch (data->uart_cfg.stop_bits) {
	case UART_CFG_STOP_BITS_1:
	/* Default value, already set. */
	break;
	case UART_CFG_STOP_BITS_2:
	*CCR3(config->base) \|= CCR3_MASK_STP;
	break;
	default:
	LOG_ERR("Selected bit stop length is not supported: %u.", data->uart_cfg.stop_bits);
	return -ENOTSUP;
	}

	switch (data->uart_cfg.data_bits) {
	case UART_CFG_DATA_BITS_7:
	*CCR3(config->base) \|= CCR3_CHR_7BIT;
	break;
	case UART_CFG_DATA_BITS_8:
	*CCR3(config->base) \|= CCR3_CHR_8BIT;
	break;
	default:
	LOG_ERR("Selected number of data bits is not supported: %u.",
	data->uart_cfg.data_bits);
	return -ENOTSUP;
	}

	if (data->uart_cfg.baudrate > ARRAY_SIZE(baud_settings)) {
	LOG_ERR("Selected baudrate variant is not supported: %u.", data->uart_cfg.baudrate);
	return -ENOTSUP;
	}
	baud_setting = baud_settings[data->uart_cfg.baudrate];

	*CCR2(config->base) &= ~(CCR2_MASK_BAUD_SETTING);
	*CCR2(config->base) \|= (baud_setting & CCR2_MASK_BAUD_SETTING);

	*CCR1(config->base) \|= (CCR1_MASK_NFEN \| CCR1_MASK_SPB2DT \| CCR1_MASK_SPB2IO);

	switch (data->uart_cfg.parity) {
	case UART_CFG_PARITY_NONE:
	/* Default value, already set. */
	break;
	case UART_CFG_PARITY_EVEN:
	*CCR1(config->base) \|= CCR1_MASK_PE;
	break;
	case UART_CFG_PARITY_ODD:
	*CCR1(config->base) \|= (CCR1_MASK_PE \| CCR1_MASK_PM);
	break;
	default:
	LOG_ERR("Unsupported parity: %u", data->uart_cfg.parity);
	}

	/* Specify trigger thresholds and clear FIFOs. */
	*FCR(config->base) = FCR_MASK_TFRST \| FCR_MASK_RFRST \| FCR_TTRG_15 \| FCR_RTRG_15;

	/* Enable the clock. */
	*CCR3(config->base) &= ~CCR3_MASK_CKE;
	*CCR3(config->base) \|= CCR3_CKE_ENABLE;

	/* Clear status flags. */
	*CFCLR(config->base) = CFCLR_ALL_FLAG_CLEAR;
	*FFCLR(config->base) = FFCLR_MASK_DRC;

	#ifdef CONFIG_UART_INTERRUPT_DRIVEN
	config->irq_config_func(dev);
	#endif /* CONFIG_UART_INTERRUPT_DRIVEN */

	/* Start transmitter and receiver. */
	*CCR0(config->base) \|= (CCR0_MASK_TE \| CCR0_MASK_RE);
	while (!(*CCR0(config->base) & CCR0_MASK_RE)) {
	}
	while (!(*CCR0(config->base) & CCR0_MASK_TE)) {
	}

	rzt2m_lock_prcrs(PRCRS_GPIO);
	rzt2m_lock_prcrn(PRCRN_PRC1 \| PRCRN_PRC2);

	return 0;
	}

	static void uart_rzt2m_isr(const struct device *dev)
	{
	const struct rzt2m_device_config *config = dev->config;
	#ifdef CONFIG_UART_INTERRUPT_DRIVEN
	struct rzt2m_device_data *data = dev->data;

	if (data->callback) {
	data->callback(dev, data->callback_data);
	}
	#endif /* CONFIG_UART_INTERRUPT_DRIVEN */

	*CFCLR(config->base) = CFCLR_MASK_RDRFC;
	*FFCLR(config->base) = FFCLR_MASK_DRC;
	}

	#define UART_RZT2M_IRQ_CONNECT(n, irq_name) \
	do { \
	IRQ_CONNECT(DT_INST_IRQ_BY_NAME(n, irq_name, irq), \
	DT_INST_IRQ_BY_NAME(n, irq_name, priority), uart_rzt2m_isr, \
	DEVICE_DT_INST_GET(n), DT_INST_IRQ_BY_NAME(n, irq_name, flags)); \
	irq_enable(DT_INST_IRQ_BY_NAME(n, irq_name, irq)); \
	} while (false)

	#define UART_RZT2M_CONFIG_FUNC(n) \
	static void uart##n##_rzt2m_irq_config(const struct device *port) \
	{ \
	UART_RZT2M_IRQ_CONNECT(n, rx_err); \
	UART_RZT2M_IRQ_CONNECT(n, rx); \
	UART_RZT2M_IRQ_CONNECT(n, tx); \
	UART_RZT2M_IRQ_CONNECT(n, tx_end); \
	}

	#define UART_RZT2M_INIT(n) \
	PINCTRL_DT_INST_DEFINE(n); \
	static struct rzt2m_device_data rzt2m_uart_##n##data = { \
	.uart_cfg = \
	{ \
	.baudrate = DT_INST_ENUM_IDX(n, current_speed), \
	.parity = DT_INST_ENUM_IDX(n, parity), \
	.stop_bits = DT_INST_ENUM_IDX(n, stop_bits), \
	.data_bits = DT_INST_ENUM_IDX(n, data_bits), \
	}, \
	}; \
	UART_RZT2M_CONFIG_FUNC(n); \
	static const struct rzt2m_device_config rzt2m_uart_##n##_config = { \
	.base = DT_INST_REG_ADDR(n), \
	.irq_config_func = uart##n##_rzt2m_irq_config, \
	.pin_config = PINCTRL_DT_INST_DEV_CONFIG_GET(n)}; \
	DEVICE_DT_INST_DEFINE(n, rzt2m_uart_init, NULL, &rzt2m_uart_##n##data, \
	&rzt2m_uart_##n##_config, PRE_KERNEL_1, CONFIG_SERIAL_INIT_PRIORITY, \
	&rzt2m_uart_api);

	DT_INST_FOREACH_STATUS_OKAY(UART_RZT2M_INIT)