drivers/serial/uart_nrfx_uart.c

/*
 * Copyright (c) 2016-2018 Nordic Semiconductor ASA
 *
 * SPDX-License-Identifier: Apache-2.0
 */

/**
 * @brief Driver for Nordic Semiconductor nRF5X UART
 */

#include <uart.h>
#include <hal/nrf_uart.h>
#include <hal/nrf_gpio.h>


static NRF_UART_Type *const uart0_addr = (NRF_UART_Type *)CONFIG_UART_0_BASE;

#ifdef CONFIG_UART_0_INTERRUPT_DRIVEN

static uart_irq_callback_user_data_t irq_callback; /**< Callback function pointer */
static void *irq_cb_data; /**< Callback function arg */

/* Variable used to override the state of the TXDRDY event in the initial state
 * of the driver. This event is not set by the hardware until a first byte is
 * sent, and we want to use it as an indication if the transmitter is ready
 * to accept a new byte.
 */
static volatile u8_t uart_sw_event_txdrdy;

#endif /* CONFIG_UART_0_INTERRUPT_DRIVEN */


static bool event_txdrdy_check(void)
{
	return (nrf_uart_event_check(uart0_addr, NRF_UART_EVENT_TXDRDY)
#ifdef CONFIG_UART_0_INTERRUPT_DRIVEN
		|| uart_sw_event_txdrdy
#endif
	       );
}

static void event_txdrdy_clear(void)
{
	nrf_uart_event_clear(uart0_addr, NRF_UART_EVENT_TXDRDY);
#ifdef CONFIG_UART_0_INTERRUPT_DRIVEN
	uart_sw_event_txdrdy = 0;
#endif
}


/**
 * @brief Set the baud rate
 *
 * This routine set the given baud rate for the UART.
 *
 * @param dev UART device struct
 * @param baudrate Baud rate
 *
 * @return N/A
 */

static int baudrate_set(struct device *dev, u32_t baudrate)
{
	nrf_uart_baudrate_t nrf_baudrate; /* calculated baudrate divisor */

	switch (baudrate) {
	case 300:
		/* value not supported by Nordic HAL */
		nrf_baudrate = 0x00014000;
		break;
	case 600:
		/* value not supported by Nordic HAL */
		nrf_baudrate = 0x00027000;
		break;
	case 1200:
		nrf_baudrate = NRF_UART_BAUDRATE_1200;
		break;
	case 2400:
		nrf_baudrate = NRF_UART_BAUDRATE_2400;
		break;
	case 4800:
		nrf_baudrate = NRF_UART_BAUDRATE_4800;
		break;
	case 9600:
		nrf_baudrate = NRF_UART_BAUDRATE_9600;
		break;
	case 14400:
		nrf_baudrate = NRF_UART_BAUDRATE_14400;
		break;
	case 19200:
		nrf_baudrate = NRF_UART_BAUDRATE_19200;
		break;
	case 28800:
		nrf_baudrate = NRF_UART_BAUDRATE_28800;
		break;
	case 31250:
		nrf_baudrate = NRF_UART_BAUDRATE_31250;
		break;
	case 38400:
		nrf_baudrate = NRF_UART_BAUDRATE_38400;
		break;
	case 56000:
		nrf_baudrate = NRF_UART_BAUDRATE_56000;
		break;
	case 57600:
		nrf_baudrate = NRF_UART_BAUDRATE_57600;
		break;
	case 76800:
		nrf_baudrate = NRF_UART_BAUDRATE_76800;
		break;
	case 115200:
		nrf_baudrate = NRF_UART_BAUDRATE_115200;
		break;
	case 230400:
		nrf_baudrate = NRF_UART_BAUDRATE_230400;
		break;
	case 250000:
		nrf_baudrate = NRF_UART_BAUDRATE_250000;
		break;
	case 460800:
		nrf_baudrate = NRF_UART_BAUDRATE_460800;
		break;
	case 921600:
		nrf_baudrate = NRF_UART_BAUDRATE_921600;
		break;
	case 1000000:
		nrf_baudrate = NRF_UART_BAUDRATE_1000000;
		break;
	default:
		return -EINVAL;
	}

	nrf_uart_baudrate_set(uart0_addr, nrf_baudrate);

	return 0;
}

/**
 * @brief Poll the device for input.
 *
 * @param dev UART device struct
 * @param c Pointer to character
 *
 * @return 0 if a character arrived, -1 if the input buffer if empty.
 */

static int uart_nrfx_poll_in(struct device *dev, unsigned char *c)
{
	if (!nrf_uart_event_check(uart0_addr, NRF_UART_EVENT_RXDRDY)) {
		return -1;
	}

	/* Clear the interrupt */
	nrf_uart_event_clear(uart0_addr, NRF_UART_EVENT_RXDRDY);

	/* got a character */
	*c = nrf_uart_rxd_get(uart0_addr);

	return 0;
}

/**
 * @brief Output a character in polled mode.
 *
 * @param dev UART device struct
 * @param c Character to send
 *
 * @return Sent character
 */
static unsigned char uart_nrfx_poll_out(struct device *dev,
					unsigned char c)
{
	/* The UART API dictates that poll_out should wait for the transmitter
	 * to be empty before sending a character. However, without locking,
	 * this introduces a rare yet possible race condition if the thread is
	 * preempted between sending the byte and checking for completion.

	 * Because of this race condition, the while loop has to be placed
	 * after the write to TXD, and we can't wait for an empty transmitter
	 * before writing. This is a trade-off between losing a byte once in a
	 * blue moon against hanging up the whole thread permanently
	 */

	/* Reset the transmitter ready state. */
	event_txdrdy_clear();

	/* Activate the transmitter. */
	nrf_uart_task_trigger(uart0_addr, NRF_UART_TASK_STARTTX);

	/* Send the provided character. */
	nrf_uart_txd_set(uart0_addr, (u8_t)c);

	/* Wait until the transmitter is ready, i.e. the character is sent. */
	while (!event_txdrdy_check()) {
	}

	/* Deactivate the transmitter so that it does not needlessly consume
	 * power.
	 */
	nrf_uart_task_trigger(uart0_addr, NRF_UART_TASK_STOPTX);

	return c;
}

/** Console I/O function */
static int uart_nrfx_err_check(struct device *dev)
{
	u32_t error = 0;

	if (nrf_uart_event_check(uart0_addr, NRF_UART_EVENT_ERROR)) {
		/* register bitfields maps to the defines in uart.h */
		error = nrf_uart_errorsrc_get_and_clear(uart0_addr);
	}

	return error;
}


#ifdef CONFIG_UART_0_INTERRUPT_DRIVEN

/** Interrupt driven FIFO fill function */
static int uart_nrfx_fifo_fill(struct device *dev,
			       const u8_t *tx_data,
			       int len)
{
	u8_t num_tx = 0;

	while ((len - num_tx > 0) &&
	       event_txdrdy_check()) {

		/* Clear the interrupt */
		event_txdrdy_clear();

		/* Send a character */
		nrf_uart_txd_set(uart0_addr, (u8_t)tx_data[num_tx++]);
	}

	return (int)num_tx;
}

/** Interrupt driven FIFO read function */
static int uart_nrfx_fifo_read(struct device *dev,
			       u8_t *rx_data,
			       const int size)
{
	u8_t num_rx = 0;

	while ((size - num_rx > 0) &&
	       nrf_uart_event_check(uart0_addr, NRF_UART_EVENT_RXDRDY)) {
		/* Clear the interrupt */
		nrf_uart_event_clear(uart0_addr, NRF_UART_EVENT_RXDRDY);

		/* Receive a character */
		rx_data[num_rx++] = (u8_t)nrf_uart_rxd_get(uart0_addr);
	}

	return num_rx;
}

/** Interrupt driven transfer enabling function */
static void uart_nrfx_irq_tx_enable(struct device *dev)
{
	u32_t key;

	/* Indicate that this device started a transaction that should not be
	 * interrupted by putting the SoC into the deep sleep mode.
	 */
	device_busy_set(dev);

	/* Activate the transmitter. */
	nrf_uart_task_trigger(uart0_addr, NRF_UART_TASK_STARTTX);

	nrf_uart_int_enable(uart0_addr, NRF_UART_INT_MASK_TXDRDY);

	/* Critical section is used to avoid any UART related interrupt which
	 * can occur after the if statement and before call of the function
	 * forcing an interrupt.
	 */
	key = irq_lock();
	if (uart_sw_event_txdrdy) {
		/* Due to HW limitation first TXDRDY interrupt shall be
		 * triggered by the software.
		 */
		NVIC_SetPendingIRQ(CONFIG_UART_0_IRQ_NUM);
	}
	irq_unlock(key);
}

/** Interrupt driven transfer disabling function */
static void uart_nrfx_irq_tx_disable(struct device *dev)
{
	nrf_uart_int_disable(uart0_addr, NRF_UART_INT_MASK_TXDRDY);

	/* Deactivate the transmitter so that it does not needlessly consume
	 * power.
	 */
	nrf_uart_task_trigger(uart0_addr, NRF_UART_TASK_STOPTX);

	/* The transaction is over. It is okay to enter the deep sleep mode
	 * if needed.
	 */
	device_busy_clear(dev);
}

/** Interrupt driven receiver enabling function */
static void uart_nrfx_irq_rx_enable(struct device *dev)
{
	nrf_uart_int_enable(uart0_addr, NRF_UART_INT_MASK_RXDRDY);
}

/** Interrupt driven receiver disabling function */
static void uart_nrfx_irq_rx_disable(struct device *dev)
{
	nrf_uart_int_disable(uart0_addr, NRF_UART_INT_MASK_RXDRDY);
}

/** Interrupt driven transfer empty function */
static int uart_nrfx_irq_tx_ready_complete(struct device *dev)
{
	return event_txdrdy_check();
}

/** Interrupt driven receiver ready function */
static int uart_nrfx_irq_rx_ready(struct device *dev)
{
	return nrf_uart_event_check(uart0_addr, NRF_UART_EVENT_RXDRDY);
}

/** Interrupt driven error enabling function */
static void uart_nrfx_irq_err_enable(struct device *dev)
{
	nrf_uart_int_enable(uart0_addr, NRF_UART_INT_MASK_ERROR);
}

/** Interrupt driven error disabling function */
static void uart_nrfx_irq_err_disable(struct device *dev)
{
	nrf_uart_int_disable(uart0_addr, NRF_UART_INT_MASK_ERROR);
}

/** Interrupt driven pending status function */
static int uart_nrfx_irq_is_pending(struct device *dev)
{
	return ((nrf_uart_int_enable_check(uart0_addr,
					   NRF_UART_INT_MASK_TXDRDY) &&
		 event_txdrdy_check())
		||
		(nrf_uart_int_enable_check(uart0_addr,
					   NRF_UART_INT_MASK_RXDRDY) &&
		 uart_nrfx_irq_rx_ready(dev)));
}

/** Interrupt driven interrupt update function */
static int uart_nrfx_irq_update(struct device *dev)
{
	return 1;
}

/** Set the callback function */
static void uart_nrfx_irq_callback_set(struct device *dev,
				       uart_irq_callback_user_data_t cb,
				       void *cb_data)
{
	(void)dev;
	irq_callback = cb;
	irq_cb_data = cb_data;
}

/**
 * @brief Interrupt service routine.
 *
 * This simply calls the callback function, if one exists.
 *
 * @param arg Argument to ISR.
 *
 * @return N/A
 */
static void uart_nrfx_isr(void *arg)
{
	ARG_UNUSED(arg);

	if (irq_callback) {
		irq_callback(irq_cb_data);
	}
}
#endif /* CONFIG_UART_0_INTERRUPT_DRIVEN */

DEVICE_DECLARE(uart_nrfx_uart0);

/**
 * @brief Initialize UART channel
 *
 * This routine is called to reset the chip in a quiescent state.
 * It is assumed that this function is called only once per UART.
 *
 * @param dev UART device struct
 *
 * @return 0 on success
 */
static int uart_nrfx_init(struct device *dev)
{
	int err;

	/* Setting default height state of the TX PIN to avoid glitches
	 * on the line during peripheral activation/deactivation.
	 */
	nrf_gpio_pin_write(CONFIG_UART_0_NRF_TX_PIN, 1);
	nrf_gpio_cfg_output(CONFIG_UART_0_NRF_TX_PIN);

	nrf_gpio_cfg_input(CONFIG_UART_0_NRF_RX_PIN, NRF_GPIO_PIN_NOPULL);

	nrf_uart_txrx_pins_set(uart0_addr,
			       CONFIG_UART_0_NRF_TX_PIN,
			       CONFIG_UART_0_NRF_RX_PIN);

#ifdef CONFIG_UART_0_NRF_FLOW_CONTROL
	/* Setting default height state of the RTS PIN to avoid glitches
	 * on the line during peripheral activation/deactivation.
	 */
	nrf_gpio_pin_write(CONFIG_UART_0_NRF_RTS_PIN, 1);
	nrf_gpio_cfg_output(CONFIG_UART_0_NRF_RTS_PIN);

	nrf_gpio_cfg_input(CONFIG_UART_0_NRF_CTS_PIN, NRF_GPIO_PIN_NOPULL);

	nrf_uart_hwfc_pins_set(uart0_addr,
			       CONFIG_UART_0_NRF_RTS_PIN,
			       CONFIG_UART_0_NRF_CTS_PIN);
#endif /* CONFIG_UART_0_NRF_FLOW_CONTROL */

	nrf_uart_configure(uart0_addr,
#ifdef CONFIG_UART_0_NRF_PARITY_BIT
			   NRF_UART_PARITY_INCLUDED,
#else
			   NRF_UART_PARITY_EXCLUDED,
#endif /* CONFIG_UART_0_NRF_PARITY_BIT */
#ifdef CONFIG_UART_0_NRF_FLOW_CONTROL
			   NRF_UART_HWFC_ENABLED);
#else
			   NRF_UART_HWFC_DISABLED);
#endif /* CONFIG_UART_0_NRF_PARITY_BIT */

	/* Set baud rate */
	err = baudrate_set(dev, CONFIG_UART_0_BAUD_RATE);
	if (err) {
		return err;
	}

	/* Enable the UART and activate its receiver. With the current API
	 * the receiver needs to be active all the time. The transmitter
	 * will be activated when there is something to send.
	 */
	nrf_uart_enable(uart0_addr);

	nrf_uart_event_clear(uart0_addr, NRF_UART_EVENT_RXDRDY);

	nrf_uart_task_trigger(uart0_addr, NRF_UART_TASK_STARTRX);

#ifdef CONFIG_UART_0_INTERRUPT_DRIVEN
	/* Simulate that the TXDRDY event is set, so that the transmitter status
	 * is indicated correctly.
	 */
	uart_sw_event_txdrdy = 1;

	IRQ_CONNECT(CONFIG_UART_0_IRQ_NUM,
		    CONFIG_UART_0_IRQ_PRI,
		    uart_nrfx_isr,
		    DEVICE_GET(uart_nrfx_uart0),
		    0);
	irq_enable(CONFIG_UART_0_IRQ_NUM);
#endif

	return 0;
}

/* Common function: uart_nrfx_irq_tx_ready_complete is used for two API entries
 * because Nordic hardware does not distinguish between them.
 */
static const struct uart_driver_api uart_nrfx_uart_driver_api = {
	.poll_in          = uart_nrfx_poll_in,
	.poll_out         = uart_nrfx_poll_out,
	.err_check        = uart_nrfx_err_check,
#ifdef CONFIG_UART_0_INTERRUPT_DRIVEN
	.fifo_fill        = uart_nrfx_fifo_fill,
	.fifo_read        = uart_nrfx_fifo_read,
	.irq_tx_enable    = uart_nrfx_irq_tx_enable,
	.irq_tx_disable   = uart_nrfx_irq_tx_disable,
	.irq_tx_ready     = uart_nrfx_irq_tx_ready_complete,
	.irq_rx_enable    = uart_nrfx_irq_rx_enable,
	.irq_rx_disable   = uart_nrfx_irq_rx_disable,
	.irq_tx_complete  = uart_nrfx_irq_tx_ready_complete,
	.irq_rx_ready     = uart_nrfx_irq_rx_ready,
	.irq_err_enable   = uart_nrfx_irq_err_enable,
	.irq_err_disable  = uart_nrfx_irq_err_disable,
	.irq_is_pending   = uart_nrfx_irq_is_pending,
	.irq_update       = uart_nrfx_irq_update,
	.irq_callback_set = uart_nrfx_irq_callback_set,
#endif /* CONFIG_UART_0_INTERRUPT_DRIVEN */
};

#ifdef CONFIG_DEVICE_POWER_MANAGEMENT
static void uart_nrfx_set_power_state(u32_t new_state)
{
	if (new_state == DEVICE_PM_ACTIVE_STATE) {
		nrf_uart_enable(uart0_addr);
		nrf_uart_task_trigger(uart0_addr, NRF_UART_TASK_STARTRX);
	} else {
		assert(new_state == DEVICE_PM_LOW_POWER_STATE ||
		       new_state == DEVICE_PM_SUSPEND_STATE ||
		       new_state == DEVICE_PM_OFF_STATE);
		nrf_uart_disable(uart0_addr);
	}
}

static int uart_nrfx_pm_control(struct device *dev,
				u32_t ctrl_command,
				void *context)
{
	static u32_t current_state = DEVICE_PM_ACTIVE_STATE;

	if (ctrl_command == DEVICE_PM_SET_POWER_STATE) {
		u32_t new_state = *((const u32_t *)context);

		if (new_state != current_state) {
			uart_nrfx_set_power_state(new_state);
			current_state = new_state;
		}
	} else {
		assert(ctrl_command == DEVICE_PM_GET_POWER_STATE);
		*((u32_t *)context) = current_state;
	}

	return 0;
}
#endif /* CONFIG_DEVICE_POWER_MANAGEMENT */

DEVICE_DEFINE(uart_nrfx_uart0,
	      CONFIG_UART_0_NAME,
	      uart_nrfx_init,
	      uart_nrfx_pm_control,
	      NULL,
	      NULL,
	      /* Initialize UART device before UART console. */
	      PRE_KERNEL_1,
	      CONFIG_KERNEL_INIT_PRIORITY_DEVICE,
	      &uart_nrfx_uart_driver_api);