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

 /*
  * Copyright (c) 2017 Piotr Mienkowski
  * Copyright (c) 2018 Justin Watson
  * Copyright (c) 2023 Gerson Fernando Budke
  * SPDX-License-Identifier: Apache-2.0
  */

 #define DT_DRV_COMPAT atmel_sam_uart

 /** @file
  * @brief UART driver for Atmel SAM MCU family.
  */

 #include <errno.h>
 #include <zephyr/sys/__assert.h>
 #include <zephyr/device.h>
 #include <zephyr/init.h>
 #include <soc.h>
 #include <zephyr/drivers/uart.h>
 #include <zephyr/drivers/pinctrl.h>
 #include <zephyr/drivers/clock_control/atmel_sam_pmc.h>
 #include <zephyr/irq.h>

 /* Device constant configuration parameters */
 struct uart_sam_dev_cfg {
 	Uart *regs;
 	const struct atmel_sam_pmc_config clock_cfg;
 	const struct pinctrl_dev_config *pcfg;

 #ifdef CONFIG_UART_INTERRUPT_DRIVEN
 	uart_irq_config_func_t	irq_config_func;
 #endif
 };

 /* Device run time data */
 struct uart_sam_dev_data {
 	uint32_t baud_rate;

 #ifdef CONFIG_UART_INTERRUPT_DRIVEN
 	uart_irq_callback_user_data_t irq_cb;	/* Interrupt Callback */
 	void *irq_cb_data;			/* Interrupt Callback Arg */
 #endif /* CONFIG_UART_INTERRUPT_DRIVEN */
 };

 static int uart_sam_poll_in(const struct device *dev, unsigned char *c)
 {
 	const struct uart_sam_dev_cfg *const cfg = dev->config;

 	Uart * const uart = cfg->regs;

 	if (!(uart->UART_SR & UART_SR_RXRDY)) {
 		return -1;
 	}

 	/* got a character */
 	*c = (unsigned char)uart->UART_RHR;

 	return 0;
 }

 static void uart_sam_poll_out(const struct device *dev, unsigned char c)
 {
 	const struct uart_sam_dev_cfg *const cfg = dev->config;

 	Uart * const uart = cfg->regs;

 	/* Wait for transmitter to be ready */
 	while (!(uart->UART_SR & UART_SR_TXRDY)) {
 	}

 	/* send a character */
 	uart->UART_THR = (uint32_t)c;
 }

 static int uart_sam_err_check(const struct device *dev)
 {
 	const struct uart_sam_dev_cfg *const cfg = dev->config;

 	volatile Uart * const uart = cfg->regs;
 	int errors = 0;

 	if (uart->UART_SR & UART_SR_OVRE) {
 		errors |= UART_ERROR_OVERRUN;
 	}

 	if (uart->UART_SR & UART_SR_PARE) {
 		errors |= UART_ERROR_PARITY;
 	}

 	if (uart->UART_SR & UART_SR_FRAME) {
 		errors |= UART_ERROR_FRAMING;
 	}

 	uart->UART_CR = UART_CR_RSTSTA;

 	return errors;
 }

 static int uart_sam_baudrate_set(const struct device *dev, uint32_t baudrate)
 {
 	struct uart_sam_dev_data *const dev_data = dev->data;

 	const struct uart_sam_dev_cfg *const cfg = dev->config;

 	volatile Uart * const uart = cfg->regs;

 	uint32_t divisor;

 	__ASSERT(baudrate,
 		 "baud rate has to be bigger than 0");
 	__ASSERT(SOC_ATMEL_SAM_MCK_FREQ_HZ/16U >= baudrate,
 		 "MCK frequency is too small to set required baud rate");

 	divisor = SOC_ATMEL_SAM_MCK_FREQ_HZ / 16U / baudrate;

 	if (divisor > 0xFFFF) {
 		return -EINVAL;
 	}

 	uart->UART_BRGR = UART_BRGR_CD(divisor);
 	dev_data->baud_rate = baudrate;

 	return 0;
 }

 static uint32_t uart_sam_cfg2sam_parity(uint8_t parity)
 {
 	switch (parity) {
 	case UART_CFG_PARITY_EVEN:
 		return UART_MR_PAR_EVEN;
 	case UART_CFG_PARITY_ODD:
 		return UART_MR_PAR_ODD;
 	case UART_CFG_PARITY_SPACE:
 		return UART_MR_PAR_SPACE;
 	case UART_CFG_PARITY_MARK:
 		return UART_MR_PAR_MARK;
 	case UART_CFG_PARITY_NONE:
 	default:
 		return UART_MR_PAR_NO;
 	}
 }

 static uint8_t uart_sam_get_parity(const struct device *dev)
 {
 	const struct uart_sam_dev_cfg *const cfg = dev->config;

 	volatile Uart * const uart = cfg->regs;

 	switch (uart->UART_MR & UART_MR_PAR_Msk) {
 	case UART_MR_PAR_EVEN:
 		return UART_CFG_PARITY_EVEN;
 	case UART_MR_PAR_ODD:
 		return UART_CFG_PARITY_ODD;
 	case UART_MR_PAR_SPACE:
 		return UART_CFG_PARITY_SPACE;
 	case UART_MR_PAR_MARK:
 		return UART_CFG_PARITY_MARK;
 	case UART_MR_PAR_NO:
 	default:
 		return UART_CFG_PARITY_NONE;
 	}
 }

 static int uart_sam_configure(const struct device *dev,
 				const struct uart_config *cfg)
 {
 	int retval;

 	const struct uart_sam_dev_cfg *const config = dev->config;

 	volatile Uart * const uart = config->regs;

 	/* Driver only supports 8 data bits, 1 stop bit, and no flow control */
 	if (cfg->stop_bits != UART_CFG_STOP_BITS_1 ||
 		cfg->data_bits != UART_CFG_DATA_BITS_8 ||
 		cfg->flow_ctrl != UART_CFG_FLOW_CTRL_NONE) {
 		return -ENOTSUP;
 	}

 	/* Reset and disable UART */
 	uart->UART_CR = UART_CR_RSTRX | UART_CR_RSTTX
 		      | UART_CR_RXDIS | UART_CR_TXDIS
 		      | UART_CR_RSTSTA;

 	/* baud rate driven by the peripheral clock, UART does not filter
 	 * the receive line, parity chosen by config
 	 */
 	uart->UART_MR = UART_MR_CHMODE_NORMAL
 		      | uart_sam_cfg2sam_parity(cfg->parity);

 	/* Set baud rate */
 	retval = uart_sam_baudrate_set(dev, cfg->baudrate);
 	if (retval != 0) {
 		return retval;
 	}

 	/* Enable receiver and transmitter */
 	uart->UART_CR = UART_CR_RXEN | UART_CR_TXEN;

 	return 0;
 }

 static int uart_sam_config_get(const struct device *dev,
 				 struct uart_config *cfg)
 {
 	struct uart_sam_dev_data *const dev_data = dev->data;

 	cfg->baudrate = dev_data->baud_rate;
 	cfg->parity = uart_sam_get_parity(dev);
 	/* only supported mode for this peripheral */
 	cfg->stop_bits = UART_CFG_STOP_BITS_1;
 	cfg->data_bits = UART_CFG_DATA_BITS_8;
 	cfg->flow_ctrl = UART_CFG_FLOW_CTRL_NONE;

 	return 0;
 }

 #ifdef CONFIG_UART_INTERRUPT_DRIVEN

 static int uart_sam_fifo_fill(const struct device *dev,
 			      const uint8_t *tx_data,
 			      int size)
 {
 	const struct uart_sam_dev_cfg *const cfg = dev->config;

 	volatile Uart * const uart = cfg->regs;

 	/* Wait for transmitter to be ready. */
 	while ((uart->UART_SR & UART_SR_TXRDY) == 0) {
 	}

 	uart->UART_THR = *tx_data;

 	return 1;
 }

 static int uart_sam_fifo_read(const struct device *dev, uint8_t *rx_data,
 			      const int size)
 {
 	const struct uart_sam_dev_cfg *const cfg = dev->config;

 	volatile Uart * const uart = cfg->regs;
 	int bytes_read;

 	bytes_read = 0;

 	while (bytes_read < size) {
 		if (uart->UART_SR & UART_SR_RXRDY) {
 			rx_data[bytes_read] = uart->UART_RHR;
 			bytes_read++;
 		} else {
 			break;
 		}
 	}

 	return bytes_read;
 }

 static void uart_sam_irq_tx_enable(const struct device *dev)
 {
 	const struct uart_sam_dev_cfg *const cfg = dev->config;

 	volatile Uart * const uart = cfg->regs;

 	uart->UART_IER = UART_IER_TXRDY;
 }

 static void uart_sam_irq_tx_disable(const struct device *dev)
 {
 	const struct uart_sam_dev_cfg *const cfg = dev->config;

 	volatile Uart * const uart = cfg->regs;

 	uart->UART_IDR = UART_IDR_TXRDY;
 }

 static int uart_sam_irq_tx_ready(const struct device *dev)
 {
 	const struct uart_sam_dev_cfg *const cfg = dev->config;

 	volatile Uart * const uart = cfg->regs;

 	/* Check that the transmitter is ready but only
 	 * return true if the interrupt is also enabled
 	 */
 	return (uart->UART_SR & UART_SR_TXRDY &&
 		uart->UART_IMR & UART_IMR_TXRDY);
 }

 static void uart_sam_irq_rx_enable(const struct device *dev)
 {
 	const struct uart_sam_dev_cfg *const cfg = dev->config;

 	volatile Uart * const uart = cfg->regs;

 	uart->UART_IER = UART_IER_RXRDY;
 }

 static void uart_sam_irq_rx_disable(const struct device *dev)
 {
 	const struct uart_sam_dev_cfg *const cfg = dev->config;

 	volatile Uart * const uart = cfg->regs;

 	uart->UART_IDR = UART_IDR_RXRDY;
 }

 static int uart_sam_irq_tx_complete(const struct device *dev)
 {
 	const struct uart_sam_dev_cfg *const cfg = dev->config;

 	volatile Uart * const uart = cfg->regs;

 	return (uart->UART_SR & UART_SR_TXRDY &&
 		uart->UART_IMR & UART_IMR_TXEMPTY);
 }

 static int uart_sam_irq_rx_ready(const struct device *dev)
 {
 	const struct uart_sam_dev_cfg *const cfg = dev->config;

 	volatile Uart * const uart = cfg->regs;

 	return (uart->UART_SR & UART_SR_RXRDY);
 }

 static void uart_sam_irq_err_enable(const struct device *dev)
 {
 	const struct uart_sam_dev_cfg *const cfg = dev->config;

 	volatile Uart * const uart = cfg->regs;

 	uart->UART_IER = UART_IER_OVRE | UART_IER_FRAME | UART_IER_PARE;
 }

 static void uart_sam_irq_err_disable(const struct device *dev)
 {
 	const struct uart_sam_dev_cfg *const cfg = dev->config;

 	volatile Uart * const uart = cfg->regs;

 	uart->UART_IDR = UART_IDR_OVRE | UART_IDR_FRAME | UART_IDR_PARE;
 }

 static int uart_sam_irq_is_pending(const struct device *dev)
 {
 	const struct uart_sam_dev_cfg *const cfg = dev->config;

 	volatile Uart * const uart = cfg->regs;

 	return (uart->UART_IMR & (UART_IMR_TXRDY | UART_IMR_RXRDY)) &
 		(uart->UART_SR & (UART_SR_TXRDY | UART_SR_RXRDY));
 }

 static int uart_sam_irq_update(const struct device *dev)
 {
 	ARG_UNUSED(dev);

 	return 1;
 }

 static void uart_sam_irq_callback_set(const struct device *dev,
 				      uart_irq_callback_user_data_t cb,
 				      void *cb_data)
 {
 	struct uart_sam_dev_data *const dev_data = dev->data;

 	dev_data->irq_cb = cb;
 	dev_data->irq_cb_data = cb_data;
 }

 static void uart_sam_isr(const struct device *dev)
 {
 	struct uart_sam_dev_data *const dev_data = dev->data;

 	if (dev_data->irq_cb) {
 		dev_data->irq_cb(dev, dev_data->irq_cb_data);
 	}
 }

 #endif /* CONFIG_UART_INTERRUPT_DRIVEN */

 static int uart_sam_init(const struct device *dev)
 {
 	int retval;

 	const struct uart_sam_dev_cfg *const cfg = dev->config;

 	struct uart_sam_dev_data *const dev_data = dev->data;

 	Uart * const uart = cfg->regs;

 	/* Enable UART clock in PMC */
 	(void)clock_control_on(SAM_DT_PMC_CONTROLLER,
 			       (clock_control_subsys_t)&cfg->clock_cfg);

 	/* Connect pins to the peripheral */
 	retval = pinctrl_apply_state(cfg->pcfg, PINCTRL_STATE_DEFAULT);
 	if (retval < 0) {
 		return retval;
 	}

 	/* Disable Interrupts */
 	uart->UART_IDR = 0xFFFFFFFF;

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

 	struct uart_config uart_config = {
 		.baudrate = dev_data->baud_rate,
 		.parity = UART_CFG_PARITY_NONE,
 		.stop_bits = UART_CFG_STOP_BITS_1,
 		.data_bits = UART_CFG_DATA_BITS_8,
 		.flow_ctrl = UART_CFG_FLOW_CTRL_NONE,
 	};
 	return uart_sam_configure(dev, &uart_config);
 }

 static const struct uart_driver_api uart_sam_driver_api = {
 	.poll_in = uart_sam_poll_in,
 	.poll_out = uart_sam_poll_out,
 	.err_check = uart_sam_err_check,
 #ifdef CONFIG_UART_USE_RUNTIME_CONFIGURE
 	.configure = uart_sam_configure,
 	.config_get = uart_sam_config_get,
 #endif /* CONFIG_UART_USE_RUNTIME_CONFIGURE */
 #ifdef CONFIG_UART_INTERRUPT_DRIVEN
 	.fifo_fill = uart_sam_fifo_fill,
 	.fifo_read = uart_sam_fifo_read,
 	.irq_tx_enable = uart_sam_irq_tx_enable,
 	.irq_tx_disable = uart_sam_irq_tx_disable,
 	.irq_tx_ready = uart_sam_irq_tx_ready,
 	.irq_rx_enable = uart_sam_irq_rx_enable,
 	.irq_rx_disable = uart_sam_irq_rx_disable,
 	.irq_tx_complete = uart_sam_irq_tx_complete,
 	.irq_rx_ready = uart_sam_irq_rx_ready,
 	.irq_err_enable = uart_sam_irq_err_enable,
 	.irq_err_disable = uart_sam_irq_err_disable,
 	.irq_is_pending = uart_sam_irq_is_pending,
 	.irq_update = uart_sam_irq_update,
 	.irq_callback_set = uart_sam_irq_callback_set,
 #endif	/* CONFIG_UART_INTERRUPT_DRIVEN */
 };

 #define UART_SAM_DECLARE_CFG(n, IRQ_FUNC_INIT)				\
 	static const struct uart_sam_dev_cfg uart##n##_sam_config = {	\
 		.regs = (Uart *)DT_INST_REG_ADDR(n),			\
 		.clock_cfg = SAM_DT_INST_CLOCK_PMC_CFG(n),		\
 									\
 		.pcfg = PINCTRL_DT_INST_DEV_CONFIG_GET(n),		\
 									\
 		IRQ_FUNC_INIT						\
 	}

 #ifdef CONFIG_UART_INTERRUPT_DRIVEN
 #define UART_SAM_CONFIG_FUNC(n)						\
 	static void uart##n##_sam_irq_config_func(const struct device *port)	\
 	{								\
 		IRQ_CONNECT(DT_INST_IRQN(n),				\
 			    DT_INST_IRQ(n, priority),			\
 			    uart_sam_isr,				\
 			    DEVICE_DT_INST_GET(n), 0);			\
 		irq_enable(DT_INST_IRQN(n));				\
 	}
 #define UART_SAM_IRQ_CFG_FUNC_INIT(n)					\
 	.irq_config_func = uart##n##_sam_irq_config_func
 #define UART_SAM_INIT_CFG(n)						\
 	UART_SAM_DECLARE_CFG(n, UART_SAM_IRQ_CFG_FUNC_INIT(n))
 #else
 #define UART_SAM_CONFIG_FUNC(n)
 #define UART_SAM_IRQ_CFG_FUNC_INIT
 #define UART_SAM_INIT_CFG(n)						\
 	UART_SAM_DECLARE_CFG(n, UART_SAM_IRQ_CFG_FUNC_INIT)
 #endif

 #define UART_SAM_INIT(n)						\
 	PINCTRL_DT_INST_DEFINE(n);					\
 	static struct uart_sam_dev_data uart##n##_sam_data = {		\
 		.baud_rate = DT_INST_PROP(n, current_speed),		\
 	};								\
 									\
 	static const struct uart_sam_dev_cfg uart##n##_sam_config;	\
 									\
 	DEVICE_DT_INST_DEFINE(n, uart_sam_init,				\
 			    NULL, &uart##n##_sam_data,			\
 			    &uart##n##_sam_config, PRE_KERNEL_1,	\
 			    CONFIG_SERIAL_INIT_PRIORITY,		\
 			    &uart_sam_driver_api);			\
 									\
 	UART_SAM_CONFIG_FUNC(n)						\
 									\
 	UART_SAM_INIT_CFG(n);

 DT_INST_FOREACH_STATUS_OKAY(UART_SAM_INIT)
	/*
	* Copyright (c) 2017 Piotr Mienkowski
	* Copyright (c) 2018 Justin Watson
	* Copyright (c) 2023 Gerson Fernando Budke
	* SPDX-License-Identifier: Apache-2.0
	*/

	#define DT_DRV_COMPAT atmel_sam_uart

	/** @file
	* @brief UART driver for Atmel SAM MCU family.
	*/

	#include <errno.h>
	#include <zephyr/sys/__assert.h>
	#include <zephyr/device.h>
	#include <zephyr/init.h>
	#include <soc.h>
	#include <zephyr/drivers/uart.h>
	#include <zephyr/drivers/pinctrl.h>
	#include <zephyr/drivers/clock_control/atmel_sam_pmc.h>
	#include <zephyr/irq.h>

	/* Device constant configuration parameters */
	struct uart_sam_dev_cfg {
	Uart *regs;
	const struct atmel_sam_pmc_config clock_cfg;
	const struct pinctrl_dev_config *pcfg;

	#ifdef CONFIG_UART_INTERRUPT_DRIVEN
	uart_irq_config_func_t irq_config_func;
	#endif
	};

	/* Device run time data */
	struct uart_sam_dev_data {
	uint32_t baud_rate;

	#ifdef CONFIG_UART_INTERRUPT_DRIVEN
	uart_irq_callback_user_data_t irq_cb; /* Interrupt Callback */
	void irq_cb_data; / Interrupt Callback Arg */
	#endif /* CONFIG_UART_INTERRUPT_DRIVEN */
	};

	static int uart_sam_poll_in(const struct device dev, unsigned char c)
	{
	const struct uart_sam_dev_cfg *const cfg = dev->config;

	Uart * const uart = cfg->regs;

	if (!(uart->UART_SR & UART_SR_RXRDY)) {
	return -1;
	}

	/* got a character */
	*c = (unsigned char)uart->UART_RHR;

	return 0;
	}

	static void uart_sam_poll_out(const struct device *dev, unsigned char c)
	{
	const struct uart_sam_dev_cfg *const cfg = dev->config;

	Uart * const uart = cfg->regs;

	/* Wait for transmitter to be ready */
	while (!(uart->UART_SR & UART_SR_TXRDY)) {
	}

	/* send a character */
	uart->UART_THR = (uint32_t)c;
	}

	static int uart_sam_err_check(const struct device *dev)
	{
	const struct uart_sam_dev_cfg *const cfg = dev->config;

	volatile Uart * const uart = cfg->regs;
	int errors = 0;

	if (uart->UART_SR & UART_SR_OVRE) {
	errors \|= UART_ERROR_OVERRUN;
	}

	if (uart->UART_SR & UART_SR_PARE) {
	errors \|= UART_ERROR_PARITY;
	}

	if (uart->UART_SR & UART_SR_FRAME) {
	errors \|= UART_ERROR_FRAMING;
	}

	uart->UART_CR = UART_CR_RSTSTA;

	return errors;
	}

	static int uart_sam_baudrate_set(const struct device *dev, uint32_t baudrate)
	{
	struct uart_sam_dev_data *const dev_data = dev->data;

	const struct uart_sam_dev_cfg *const cfg = dev->config;

	volatile Uart * const uart = cfg->regs;

	uint32_t divisor;

	__ASSERT(baudrate,
	"baud rate has to be bigger than 0");
	__ASSERT(SOC_ATMEL_SAM_MCK_FREQ_HZ/16U >= baudrate,
	"MCK frequency is too small to set required baud rate");

	divisor = SOC_ATMEL_SAM_MCK_FREQ_HZ / 16U / baudrate;

	if (divisor > 0xFFFF) {
	return -EINVAL;
	}

	uart->UART_BRGR = UART_BRGR_CD(divisor);
	dev_data->baud_rate = baudrate;

	return 0;
	}

	static uint32_t uart_sam_cfg2sam_parity(uint8_t parity)
	{
	switch (parity) {
	case UART_CFG_PARITY_EVEN:
	return UART_MR_PAR_EVEN;
	case UART_CFG_PARITY_ODD:
	return UART_MR_PAR_ODD;
	case UART_CFG_PARITY_SPACE:
	return UART_MR_PAR_SPACE;
	case UART_CFG_PARITY_MARK:
	return UART_MR_PAR_MARK;
	case UART_CFG_PARITY_NONE:
	default:
	return UART_MR_PAR_NO;
	}
	}

	static uint8_t uart_sam_get_parity(const struct device *dev)
	{
	const struct uart_sam_dev_cfg *const cfg = dev->config;

	volatile Uart * const uart = cfg->regs;

	switch (uart->UART_MR & UART_MR_PAR_Msk) {
	case UART_MR_PAR_EVEN:
	return UART_CFG_PARITY_EVEN;
	case UART_MR_PAR_ODD:
	return UART_CFG_PARITY_ODD;
	case UART_MR_PAR_SPACE:
	return UART_CFG_PARITY_SPACE;
	case UART_MR_PAR_MARK:
	return UART_CFG_PARITY_MARK;
	case UART_MR_PAR_NO:
	default:
	return UART_CFG_PARITY_NONE;
	}
	}

	static int uart_sam_configure(const struct device *dev,
	const struct uart_config *cfg)
	{
	int retval;

	const struct uart_sam_dev_cfg *const config = dev->config;

	volatile Uart * const uart = config->regs;

	/* Driver only supports 8 data bits, 1 stop bit, and no flow control */
	if (cfg->stop_bits != UART_CFG_STOP_BITS_1 \|\|
	cfg->data_bits != UART_CFG_DATA_BITS_8 \|\|
	cfg->flow_ctrl != UART_CFG_FLOW_CTRL_NONE) {
	return -ENOTSUP;
	}

	/* Reset and disable UART */
	uart->UART_CR = UART_CR_RSTRX \| UART_CR_RSTTX
	\| UART_CR_RXDIS \| UART_CR_TXDIS
	\| UART_CR_RSTSTA;

	/* baud rate driven by the peripheral clock, UART does not filter
	* the receive line, parity chosen by config
	*/
	uart->UART_MR = UART_MR_CHMODE_NORMAL
	\| uart_sam_cfg2sam_parity(cfg->parity);

	/* Set baud rate */
	retval = uart_sam_baudrate_set(dev, cfg->baudrate);
	if (retval != 0) {
	return retval;
	}

	/* Enable receiver and transmitter */
	uart->UART_CR = UART_CR_RXEN \| UART_CR_TXEN;

	return 0;
	}

	static int uart_sam_config_get(const struct device *dev,
	struct uart_config *cfg)
	{
	struct uart_sam_dev_data *const dev_data = dev->data;

	cfg->baudrate = dev_data->baud_rate;
	cfg->parity = uart_sam_get_parity(dev);
	/* only supported mode for this peripheral */
	cfg->stop_bits = UART_CFG_STOP_BITS_1;
	cfg->data_bits = UART_CFG_DATA_BITS_8;
	cfg->flow_ctrl = UART_CFG_FLOW_CTRL_NONE;

	return 0;
	}

	#ifdef CONFIG_UART_INTERRUPT_DRIVEN

	static int uart_sam_fifo_fill(const struct device *dev,
	const uint8_t *tx_data,
	int size)
	{
	const struct uart_sam_dev_cfg *const cfg = dev->config;

	volatile Uart * const uart = cfg->regs;

	/* Wait for transmitter to be ready. */
	while ((uart->UART_SR & UART_SR_TXRDY) == 0) {
	}

	uart->UART_THR = *tx_data;

	return 1;
	}

	static int uart_sam_fifo_read(const struct device dev, uint8_t rx_data,
	const int size)
	{
	const struct uart_sam_dev_cfg *const cfg = dev->config;

	volatile Uart * const uart = cfg->regs;
	int bytes_read;

	bytes_read = 0;

	while (bytes_read < size) {
	if (uart->UART_SR & UART_SR_RXRDY) {
	rx_data[bytes_read] = uart->UART_RHR;
	bytes_read++;
	} else {
	break;
	}
	}

	return bytes_read;
	}

	static void uart_sam_irq_tx_enable(const struct device *dev)
	{
	const struct uart_sam_dev_cfg *const cfg = dev->config;

	volatile Uart * const uart = cfg->regs;

	uart->UART_IER = UART_IER_TXRDY;
	}

	static void uart_sam_irq_tx_disable(const struct device *dev)
	{
	const struct uart_sam_dev_cfg *const cfg = dev->config;

	volatile Uart * const uart = cfg->regs;

	uart->UART_IDR = UART_IDR_TXRDY;
	}

	static int uart_sam_irq_tx_ready(const struct device *dev)
	{
	const struct uart_sam_dev_cfg *const cfg = dev->config;

	volatile Uart * const uart = cfg->regs;

	/* Check that the transmitter is ready but only
	* return true if the interrupt is also enabled
	*/
	return (uart->UART_SR & UART_SR_TXRDY &&
	uart->UART_IMR & UART_IMR_TXRDY);
	}

	static void uart_sam_irq_rx_enable(const struct device *dev)
	{
	const struct uart_sam_dev_cfg *const cfg = dev->config;

	volatile Uart * const uart = cfg->regs;

	uart->UART_IER = UART_IER_RXRDY;
	}

	static void uart_sam_irq_rx_disable(const struct device *dev)
	{
	const struct uart_sam_dev_cfg *const cfg = dev->config;

	volatile Uart * const uart = cfg->regs;

	uart->UART_IDR = UART_IDR_RXRDY;
	}

	static int uart_sam_irq_tx_complete(const struct device *dev)
	{
	const struct uart_sam_dev_cfg *const cfg = dev->config;

	volatile Uart * const uart = cfg->regs;

	return (uart->UART_SR & UART_SR_TXRDY &&
	uart->UART_IMR & UART_IMR_TXEMPTY);
	}

	static int uart_sam_irq_rx_ready(const struct device *dev)
	{
	const struct uart_sam_dev_cfg *const cfg = dev->config;

	volatile Uart * const uart = cfg->regs;

	return (uart->UART_SR & UART_SR_RXRDY);
	}

	static void uart_sam_irq_err_enable(const struct device *dev)
	{
	const struct uart_sam_dev_cfg *const cfg = dev->config;

	volatile Uart * const uart = cfg->regs;

	uart->UART_IER = UART_IER_OVRE \| UART_IER_FRAME \| UART_IER_PARE;
	}

	static void uart_sam_irq_err_disable(const struct device *dev)
	{
	const struct uart_sam_dev_cfg *const cfg = dev->config;

	volatile Uart * const uart = cfg->regs;

	uart->UART_IDR = UART_IDR_OVRE \| UART_IDR_FRAME \| UART_IDR_PARE;
	}

	static int uart_sam_irq_is_pending(const struct device *dev)
	{
	const struct uart_sam_dev_cfg *const cfg = dev->config;

	volatile Uart * const uart = cfg->regs;

	return (uart->UART_IMR & (UART_IMR_TXRDY \| UART_IMR_RXRDY)) &
	(uart->UART_SR & (UART_SR_TXRDY \| UART_SR_RXRDY));
	}

	static int uart_sam_irq_update(const struct device *dev)
	{
	ARG_UNUSED(dev);

	return 1;
	}

	static void uart_sam_irq_callback_set(const struct device *dev,
	uart_irq_callback_user_data_t cb,
	void *cb_data)
	{
	struct uart_sam_dev_data *const dev_data = dev->data;

	dev_data->irq_cb = cb;
	dev_data->irq_cb_data = cb_data;
	}

	static void uart_sam_isr(const struct device *dev)
	{
	struct uart_sam_dev_data *const dev_data = dev->data;

	if (dev_data->irq_cb) {
	dev_data->irq_cb(dev, dev_data->irq_cb_data);
	}
	}

	#endif /* CONFIG_UART_INTERRUPT_DRIVEN */

	static int uart_sam_init(const struct device *dev)
	{
	int retval;

	const struct uart_sam_dev_cfg *const cfg = dev->config;

	struct uart_sam_dev_data *const dev_data = dev->data;

	Uart * const uart = cfg->regs;

	/* Enable UART clock in PMC */
	(void)clock_control_on(SAM_DT_PMC_CONTROLLER,
	(clock_control_subsys_t)&cfg->clock_cfg);

	/* Connect pins to the peripheral */
	retval = pinctrl_apply_state(cfg->pcfg, PINCTRL_STATE_DEFAULT);
	if (retval < 0) {
	return retval;
	}

	/* Disable Interrupts */
	uart->UART_IDR = 0xFFFFFFFF;

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

	struct uart_config uart_config = {
	.baudrate = dev_data->baud_rate,
	.parity = UART_CFG_PARITY_NONE,
	.stop_bits = UART_CFG_STOP_BITS_1,
	.data_bits = UART_CFG_DATA_BITS_8,
	.flow_ctrl = UART_CFG_FLOW_CTRL_NONE,
	};
	return uart_sam_configure(dev, &uart_config);
	}

	static const struct uart_driver_api uart_sam_driver_api = {
	.poll_in = uart_sam_poll_in,
	.poll_out = uart_sam_poll_out,
	.err_check = uart_sam_err_check,
	#ifdef CONFIG_UART_USE_RUNTIME_CONFIGURE
	.configure = uart_sam_configure,
	.config_get = uart_sam_config_get,
	#endif /* CONFIG_UART_USE_RUNTIME_CONFIGURE */
	#ifdef CONFIG_UART_INTERRUPT_DRIVEN
	.fifo_fill = uart_sam_fifo_fill,
	.fifo_read = uart_sam_fifo_read,
	.irq_tx_enable = uart_sam_irq_tx_enable,
	.irq_tx_disable = uart_sam_irq_tx_disable,
	.irq_tx_ready = uart_sam_irq_tx_ready,
	.irq_rx_enable = uart_sam_irq_rx_enable,
	.irq_rx_disable = uart_sam_irq_rx_disable,
	.irq_tx_complete = uart_sam_irq_tx_complete,
	.irq_rx_ready = uart_sam_irq_rx_ready,
	.irq_err_enable = uart_sam_irq_err_enable,
	.irq_err_disable = uart_sam_irq_err_disable,
	.irq_is_pending = uart_sam_irq_is_pending,
	.irq_update = uart_sam_irq_update,
	.irq_callback_set = uart_sam_irq_callback_set,
	#endif /* CONFIG_UART_INTERRUPT_DRIVEN */
	};

	#define UART_SAM_DECLARE_CFG(n, IRQ_FUNC_INIT) \
	static const struct uart_sam_dev_cfg uart##n##_sam_config = { \
	.regs = (Uart *)DT_INST_REG_ADDR(n), \
	.clock_cfg = SAM_DT_INST_CLOCK_PMC_CFG(n), \
	\
	.pcfg = PINCTRL_DT_INST_DEV_CONFIG_GET(n), \
	\
	IRQ_FUNC_INIT \
	}

	#ifdef CONFIG_UART_INTERRUPT_DRIVEN
	#define UART_SAM_CONFIG_FUNC(n) \
	static void uart##n##_sam_irq_config_func(const struct device *port) \
	{ \
	IRQ_CONNECT(DT_INST_IRQN(n), \
	DT_INST_IRQ(n, priority), \
	uart_sam_isr, \
	DEVICE_DT_INST_GET(n), 0); \
	irq_enable(DT_INST_IRQN(n)); \
	}
	#define UART_SAM_IRQ_CFG_FUNC_INIT(n) \
	.irq_config_func = uart##n##_sam_irq_config_func
	#define UART_SAM_INIT_CFG(n) \
	UART_SAM_DECLARE_CFG(n, UART_SAM_IRQ_CFG_FUNC_INIT(n))
	#else
	#define UART_SAM_CONFIG_FUNC(n)
	#define UART_SAM_IRQ_CFG_FUNC_INIT
	#define UART_SAM_INIT_CFG(n) \
	UART_SAM_DECLARE_CFG(n, UART_SAM_IRQ_CFG_FUNC_INIT)
	#endif

	#define UART_SAM_INIT(n) \
	PINCTRL_DT_INST_DEFINE(n); \
	static struct uart_sam_dev_data uart##n##_sam_data = { \
	.baud_rate = DT_INST_PROP(n, current_speed), \
	}; \
	\
	static const struct uart_sam_dev_cfg uart##n##_sam_config; \
	\
	DEVICE_DT_INST_DEFINE(n, uart_sam_init, \
	NULL, &uart##n##_sam_data, \
	&uart##n##_sam_config, PRE_KERNEL_1, \
	CONFIG_SERIAL_INIT_PRIORITY, \
	&uart_sam_driver_api); \
	\
	UART_SAM_CONFIG_FUNC(n) \
	\
	UART_SAM_INIT_CFG(n);

	DT_INST_FOREACH_STATUS_OKAY(UART_SAM_INIT)