diff --git a/drivers/serial/uart_cc32xx.c b/drivers/serial/uart_cc32xx.c
index a61af59579b..829254bc627 100644
--- a/drivers/serial/uart_cc32xx.c
+++ b/drivers/serial/uart_cc32xx.c
@@ -202,7 +202,7 @@ static void uart_cc32xx_irq_rx_disable(struct device *dev)
 	MAP_UARTIntDisable((unsigned long)config->base, UART_INT_RX);
 }
 
-static int uart_cc32xx_irq_tx_empty(struct device *dev)
+static int uart_cc32xx_irq_tx_complete(struct device *dev)
 {
 	const struct uart_device_config *config = DEV_CFG(dev);
 
@@ -296,7 +296,7 @@ static const struct uart_driver_api uart_cc32xx_driver_api = {
 	.irq_tx_ready	  = uart_cc32xx_irq_tx_ready,
 	.irq_rx_enable	  = uart_cc32xx_irq_rx_enable,
 	.irq_rx_disable	  = uart_cc32xx_irq_rx_disable,
-	.irq_tx_empty	  = uart_cc32xx_irq_tx_empty,
+	.irq_tx_complete  = uart_cc32xx_irq_tx_complete,
 	.irq_rx_ready	  = uart_cc32xx_irq_rx_ready,
 	.irq_err_enable	  = uart_cc32xx_irq_err_enable,
 	.irq_err_disable  = uart_cc32xx_irq_err_disable,
diff --git a/drivers/serial/uart_cmsdk_apb.c b/drivers/serial/uart_cmsdk_apb.c
index d02dfca9488..2b93aec2e1c 100644
--- a/drivers/serial/uart_cmsdk_apb.c
+++ b/drivers/serial/uart_cmsdk_apb.c
@@ -316,7 +316,7 @@ static void uart_cmsdk_apb_irq_rx_disable(struct device *dev)
  *
  * @return 1 if an interrupt is ready, 0 otherwise
  */
-static int uart_cmsdk_apb_irq_tx_empty(struct device *dev)
+static int uart_cmsdk_apb_irq_tx_complete(struct device *dev)
 {
 	return uart_cmsdk_apb_irq_tx_ready(dev);
 }
@@ -435,7 +435,7 @@ static const struct uart_driver_api uart_cmsdk_apb_driver_api = {
 	.irq_tx_ready = uart_cmsdk_apb_irq_tx_ready,
 	.irq_rx_enable = uart_cmsdk_apb_irq_rx_enable,
 	.irq_rx_disable = uart_cmsdk_apb_irq_rx_disable,
-	.irq_tx_empty = uart_cmsdk_apb_irq_tx_empty,
+	.irq_tx_complete = uart_cmsdk_apb_irq_tx_complete,
 	.irq_rx_ready = uart_cmsdk_apb_irq_rx_ready,
 	.irq_err_enable = uart_cmsdk_apb_irq_err_enable,
 	.irq_err_disable = uart_cmsdk_apb_irq_err_disable,
diff --git a/drivers/serial/uart_fe310.c b/drivers/serial/uart_fe310.c
index 0adf616859d..582400edfea 100644
--- a/drivers/serial/uart_fe310.c
+++ b/drivers/serial/uart_fe310.c
@@ -217,7 +217,7 @@ static int uart_fe310_irq_tx_ready(struct device *dev)
  *
  * @return 1 if nothing remains to be transmitted, 0 otherwise
  */
-static int uart_fe310_irq_tx_empty(struct device *dev)
+static int uart_fe310_irq_tx_complete(struct device *dev)
 {
 	volatile struct uart_fe310_regs_t *uart = DEV_UART(dev);
 
@@ -361,7 +361,7 @@ static const struct uart_driver_api uart_fe310_driver_api = {
 	.irq_tx_enable    = uart_fe310_irq_tx_enable,
 	.irq_tx_disable   = uart_fe310_irq_tx_disable,
 	.irq_tx_ready     = uart_fe310_irq_tx_ready,
-	.irq_tx_empty     = uart_fe310_irq_tx_empty,
+	.irq_tx_complete  = uart_fe310_irq_tx_complete,
 	.irq_rx_enable    = uart_fe310_irq_rx_enable,
 	.irq_rx_disable   = uart_fe310_irq_rx_disable,
 	.irq_rx_ready     = uart_fe310_irq_rx_ready,
diff --git a/drivers/serial/uart_mcux.c b/drivers/serial/uart_mcux.c
index cb8da3d0644..e1b72f3b6d0 100644
--- a/drivers/serial/uart_mcux.c
+++ b/drivers/serial/uart_mcux.c
@@ -124,7 +124,7 @@ static void uart_mcux_irq_tx_disable(struct device *dev)
 	UART_DisableInterrupts(config->base, mask);
 }
 
-static int uart_mcux_irq_tx_empty(struct device *dev)
+static int uart_mcux_irq_tx_complete(struct device *dev)
 {
 	const struct uart_mcux_config *config = dev->config->config_info;
 	u32_t flags = UART_GetStatusFlags(config->base);
@@ -138,7 +138,7 @@ static int uart_mcux_irq_tx_ready(struct device *dev)
 	u32_t mask = kUART_TxDataRegEmptyInterruptEnable;
 
 	return (UART_GetEnabledInterrupts(config->base) & mask)
-		&& uart_mcux_irq_tx_empty(dev);
+		&& uart_mcux_irq_tx_complete(dev);
 }
 
 static void uart_mcux_irq_rx_enable(struct device *dev)
@@ -254,7 +254,7 @@ static const struct uart_driver_api uart_mcux_driver_api = {
 	.fifo_read = uart_mcux_fifo_read,
 	.irq_tx_enable = uart_mcux_irq_tx_enable,
 	.irq_tx_disable = uart_mcux_irq_tx_disable,
-	.irq_tx_empty = uart_mcux_irq_tx_empty,
+	.irq_tx_complete = uart_mcux_irq_tx_complete,
 	.irq_tx_ready = uart_mcux_irq_tx_ready,
 	.irq_rx_enable = uart_mcux_irq_rx_enable,
 	.irq_rx_disable = uart_mcux_irq_rx_disable,
diff --git a/drivers/serial/uart_mcux_lpsci.c b/drivers/serial/uart_mcux_lpsci.c
index 5d6c08d6d95..359faffd0b0 100644
--- a/drivers/serial/uart_mcux_lpsci.c
+++ b/drivers/serial/uart_mcux_lpsci.c
@@ -127,7 +127,7 @@ static void mcux_lpsci_irq_tx_disable(struct device *dev)
 	LPSCI_DisableInterrupts(config->base, mask);
 }
 
-static int mcux_lpsci_irq_tx_empty(struct device *dev)
+static int mcux_lpsci_irq_tx_complete(struct device *dev)
 {
 	const struct mcux_lpsci_config *config = dev->config->config_info;
 	u32_t flags = LPSCI_GetStatusFlags(config->base);
@@ -141,7 +141,7 @@ static int mcux_lpsci_irq_tx_ready(struct device *dev)
 	u32_t mask = kLPSCI_TxDataRegEmptyInterruptEnable;
 
 	return (LPSCI_GetEnabledInterrupts(config->base) & mask)
-		&& mcux_lpsci_irq_tx_empty(dev);
+		&& mcux_lpsci_irq_tx_complete(dev);
 }
 
 static void mcux_lpsci_irq_rx_enable(struct device *dev)
@@ -258,7 +258,7 @@ static const struct uart_driver_api mcux_lpsci_driver_api = {
 	.fifo_read = mcux_lpsci_fifo_read,
 	.irq_tx_enable = mcux_lpsci_irq_tx_enable,
 	.irq_tx_disable = mcux_lpsci_irq_tx_disable,
-	.irq_tx_empty = mcux_lpsci_irq_tx_empty,
+	.irq_tx_complete = mcux_lpsci_irq_tx_complete,
 	.irq_tx_ready = mcux_lpsci_irq_tx_ready,
 	.irq_rx_enable = mcux_lpsci_irq_rx_enable,
 	.irq_rx_disable = mcux_lpsci_irq_rx_disable,
diff --git a/drivers/serial/uart_mcux_lpuart.c b/drivers/serial/uart_mcux_lpuart.c
index fa50fc27adf..02cbd0c941d 100644
--- a/drivers/serial/uart_mcux_lpuart.c
+++ b/drivers/serial/uart_mcux_lpuart.c
@@ -127,7 +127,7 @@ static void mcux_lpuart_irq_tx_disable(struct device *dev)
 	LPUART_DisableInterrupts(config->base, mask);
 }
 
-static int mcux_lpuart_irq_tx_empty(struct device *dev)
+static int mcux_lpuart_irq_tx_complete(struct device *dev)
 {
 	const struct mcux_lpuart_config *config = dev->config->config_info;
 	u32_t flags = LPUART_GetStatusFlags(config->base);
@@ -141,7 +141,7 @@ static int mcux_lpuart_irq_tx_ready(struct device *dev)
 	u32_t mask = kLPUART_TxDataRegEmptyInterruptEnable;
 
 	return (LPUART_GetEnabledInterrupts(config->base) & mask)
-		&& mcux_lpuart_irq_tx_empty(dev);
+		&& mcux_lpuart_irq_tx_complete(dev);
 }
 
 static void mcux_lpuart_irq_rx_enable(struct device *dev)
@@ -258,7 +258,7 @@ static const struct uart_driver_api mcux_lpuart_driver_api = {
 	.fifo_read = mcux_lpuart_fifo_read,
 	.irq_tx_enable = mcux_lpuart_irq_tx_enable,
 	.irq_tx_disable = mcux_lpuart_irq_tx_disable,
-	.irq_tx_empty = mcux_lpuart_irq_tx_empty,
+	.irq_tx_complete = mcux_lpuart_irq_tx_complete,
 	.irq_tx_ready = mcux_lpuart_irq_tx_ready,
 	.irq_rx_enable = mcux_lpuart_irq_rx_enable,
 	.irq_rx_disable = mcux_lpuart_irq_rx_disable,
diff --git a/drivers/serial/uart_nrf5.c b/drivers/serial/uart_nrf5.c
index 03444ed8786..c4854c233c9 100644
--- a/drivers/serial/uart_nrf5.c
+++ b/drivers/serial/uart_nrf5.c
@@ -398,7 +398,7 @@ static void uart_nrf5_irq_rx_disable(struct device *dev)
 }
 
 /** Interrupt driven transfer empty function */
-static int uart_nrf5_irq_tx_empty(struct device *dev)
+static int uart_nrf5_irq_tx_complete(struct device *dev)
 {
 	volatile struct _uart *uart = UART_STRUCT(dev);
 
@@ -481,7 +481,7 @@ static const struct uart_driver_api uart_nrf5_driver_api = {
 	.irq_tx_ready     = uart_nrf5_irq_tx_ready,     /** IRQ transfer ready function */
 	.irq_rx_enable    = uart_nrf5_irq_rx_enable,    /** IRQ receiver enabling function */
 	.irq_rx_disable   = uart_nrf5_irq_rx_disable,   /** IRQ receiver disabling function */
-	.irq_tx_empty     = uart_nrf5_irq_tx_empty,     /** IRQ transfer empty function */
+	.irq_tx_complete  = uart_nrf5_irq_tx_complete,  /** IRQ transfer complete function */
 	.irq_rx_ready     = uart_nrf5_irq_rx_ready,     /** IRQ receiver ready function */
 	.irq_err_enable   = uart_nrf5_irq_err_enable,   /** IRQ error enabling function */
 	.irq_err_disable  = uart_nrf5_irq_err_disable,  /** IRQ error disabling function */
diff --git a/drivers/serial/uart_ns16550.c b/drivers/serial/uart_ns16550.c
index 66af0ea2658..ae43b307b53 100644
--- a/drivers/serial/uart_ns16550.c
+++ b/drivers/serial/uart_ns16550.c
@@ -508,7 +508,7 @@ static int uart_ns16550_irq_tx_ready(struct device *dev)
  *
  * @return 1 if nothing remains to be transmitted, 0 otherwise
  */
-static int uart_ns16550_irq_tx_empty(struct device *dev)
+static int uart_ns16550_irq_tx_complete(struct device *dev)
 {
 	return (INBYTE(LSR(dev)) & (LSR_TEMT | LSR_THRE)) == (LSR_TEMT | LSR_THRE);
 }
@@ -721,7 +721,7 @@ static const struct uart_driver_api uart_ns16550_driver_api = {
 	.irq_tx_enable = uart_ns16550_irq_tx_enable,
 	.irq_tx_disable = uart_ns16550_irq_tx_disable,
 	.irq_tx_ready = uart_ns16550_irq_tx_ready,
-	.irq_tx_empty = uart_ns16550_irq_tx_empty,
+	.irq_tx_complete = uart_ns16550_irq_tx_complete,
 	.irq_rx_enable = uart_ns16550_irq_rx_enable,
 	.irq_rx_disable = uart_ns16550_irq_rx_disable,
 	.irq_rx_ready = uart_ns16550_irq_rx_ready,
diff --git a/drivers/serial/uart_qmsi.c b/drivers/serial/uart_qmsi.c
index 493a7228100..2da34f249c9 100644
--- a/drivers/serial/uart_qmsi.c
+++ b/drivers/serial/uart_qmsi.c
@@ -285,7 +285,7 @@ static int uart_qmsi_irq_tx_ready(struct device *dev)
 	return id == QM_UART_IIR_THR_EMPTY;
 }
 
-static int uart_qmsi_irq_tx_empty(struct device *dev)
+static int uart_qmsi_irq_tx_complete(struct device *dev)
 {
 	qm_uart_t instance = GET_CONTROLLER_INSTANCE(dev);
 	const u32_t mask = (QM_UART_LSR_TEMT | QM_UART_LSR_THRE);
@@ -433,7 +433,7 @@ static const struct uart_driver_api api = {
 	.irq_tx_enable = uart_qmsi_irq_tx_enable,
 	.irq_tx_disable = uart_qmsi_irq_tx_disable,
 	.irq_tx_ready = uart_qmsi_irq_tx_ready,
-	.irq_tx_empty = uart_qmsi_irq_tx_empty,
+	.irq_tx_complete = uart_qmsi_irq_tx_complete,
 	.irq_rx_enable = uart_qmsi_irq_rx_enable,
 	.irq_rx_disable = uart_qmsi_irq_rx_disable,
 	.irq_rx_ready = uart_qmsi_irq_rx_ready,
diff --git a/drivers/serial/uart_stm32.c b/drivers/serial/uart_stm32.c
index d7747008d43..78bb9469160 100644
--- a/drivers/serial/uart_stm32.c
+++ b/drivers/serial/uart_stm32.c
@@ -150,7 +150,7 @@ static int uart_stm32_irq_tx_ready(struct device *dev)
 	return __HAL_UART_GET_FLAG(UartHandle, UART_FLAG_TXE);
 }
 
-static int uart_stm32_irq_tx_empty(struct device *dev)
+static int uart_stm32_irq_tx_complete(struct device *dev)
 {
 	struct uart_stm32_data *data = DEV_DATA(dev);
 	UART_HandleTypeDef *UartHandle = &data->huart;
@@ -250,7 +250,7 @@ static const struct uart_driver_api uart_stm32_driver_api = {
 	.irq_tx_enable = uart_stm32_irq_tx_enable,
 	.irq_tx_disable = uart_stm32_irq_tx_disable,
 	.irq_tx_ready = uart_stm32_irq_tx_ready,
-	.irq_tx_empty = uart_stm32_irq_tx_empty,
+	.irq_tx_complete = uart_stm32_irq_tx_complete,
 	.irq_rx_enable = uart_stm32_irq_rx_enable,
 	.irq_rx_disable = uart_stm32_irq_rx_disable,
 	.irq_rx_ready = uart_stm32_irq_rx_ready,
diff --git a/include/uart.h b/include/uart.h
index 129941f19c7..4f246d75035 100644
--- a/include/uart.h
+++ b/include/uart.h
@@ -138,8 +138,8 @@ struct uart_driver_api {
 	/** Interrupt driven receiver disabling function */
 	void (*irq_rx_disable)(struct device *dev);
 
-	/** Interrupt driven transfer empty function */
-	int (*irq_tx_empty)(struct device *dev);
+	/** Interrupt driven transfer complete function */
+	int (*irq_tx_complete)(struct device *dev);
 
 	/** Interrupt driven receiver ready function */
 	int (*irq_rx_ready)(struct device *dev);
@@ -312,11 +312,18 @@ static inline void uart_irq_tx_disable(struct device *dev)
 }
 
 /**
- * @brief Check if Tx IRQ has been raised.
+ * @brief Check if UART TX buffer can accept a new char
+ *
+ * @details Check if UART TX buffer can accept at least one character
+ * for transmission (i.e. uart_fifo_fill() will succeed and return
+ * non-zero). This function must be called in a UART interrupt
+ * handler, or its result is undefined. Before calling this function
+ * in the interrupt handler, uart_irq_update() must be called once per
+ * the handler invocation.
  *
  * @param dev UART device structure.
  *
- * @retval 1 If an IRQ is ready.
+ * @retval 1 If at least one char can be written to UART.
  * @retval 0 Otherwise.
  */
 static inline int uart_irq_tx_ready(struct device *dev)
@@ -363,30 +370,52 @@ static inline void uart_irq_rx_disable(struct device *dev)
 }
 
 /**
- * @brief Check if nothing remains to be transmitted
+ * @brief Check if UART TX block finished transmission
+ *
+ * @details Check if any outgoing data buffered in UART TX block was
+ * fully transmitted and TX block is idle. When this condition is
+ * true, UART device (or whole system) can be power off. Note that
+ * this function is *not* useful to check if UART TX can accept more
+ * data, use uart_irq_tx_ready() for that. This function must be called
+ * in a UART interrupt handler, or its result is undefined. Before
+ * calling this function in the interrupt handler, uart_irq_update()
+ * must be called once per the handler invocation.
  *
  * @param dev UART device structure.
  *
  * @retval 1 If nothing remains to be transmitted.
  * @retval 0 Otherwise.
  */
-static inline int uart_irq_tx_empty(struct device *dev)
+static inline int uart_irq_tx_complete(struct device *dev)
 {
 	const struct uart_driver_api *api = dev->driver_api;
 
-	if (api->irq_tx_empty) {
-		return api->irq_tx_empty(dev);
+	if (api->irq_tx_complete) {
+		return api->irq_tx_complete(dev);
 	}
 
 	return 0;
 }
 
 /**
- * @brief Check if Rx IRQ has been raised.
+ * @deprecated This API is deprecated.
+ */
+static inline int __deprecated uart_irq_tx_empty(struct device *dev)
+{
+	return uart_irq_tx_complete(dev);
+}
+
+/**
+ * @brief Check if UART RX buffer has a new char
+ *
+ * (i.e. uart_fifo_read() will succeed and return non-zero). This function
+ * must be called in a UART interrupt handler, or its result is undefined.
+ * Before calling this function in the interrupt handler, uart_irq_update()
+ * must be called once per the handler invocation.
  *
  * @param dev UART device structure.
  *
- * @retval 1 If an IRQ is ready.
+ * @retval 1 If a new received char is ready.
  * @retval 0 Otherwise.
  */
 static inline int uart_irq_rx_ready(struct device *dev)