drivers: uart_nrfx_uarte: Fix runtime device PM for interrupt driven API

Add missing getting/putting of the device when the RX interrupt is
enabled/disabled. Also fix enabling and disabling of the TX interrupt
so that the device is got/put only if the interrupt wasn't already
enabled/disabled and device PM reference counting is done correctly.

This fixes `console_getchar()` that would hang when used with
`CONFIG_PM_DEVICE_RUNTIME=y`.

Signed-off-by: Andrzej Głąbek <[email protected]>

Author: anangl

drivers/serial/uart_nrfx_uarte.c

@@ -2832,27 +2832,35 @@ static void uarte_nrfx_irq_tx_enable(const struct device *dev)
 {
 	NRF_UARTE_Type *uarte = get_uarte_instance(dev);
 	struct uarte_nrfx_data *data = dev->data;
+	bool already_enabled;
 
-	if (IS_ENABLED(CONFIG_PM_DEVICE_RUNTIME)) {
-		pm_device_runtime_get(dev);
-	}
+	pm_device_runtime_get(dev);
 
 	unsigned int key = irq_lock();
 
-	data->int_driven->disable_tx_irq = false;
-	data->int_driven->tx_irq_enabled = true;
-	nrf_uarte_int_enable(uarte, NRF_UARTE_INT_TXSTOPPED_MASK);
+	already_enabled = data->int_driven->tx_irq_enabled;
+	if (!already_enabled) {
+		data->int_driven->disable_tx_irq = false;
+		data->int_driven->tx_irq_enabled = true;
+		nrf_uarte_int_enable(uarte, NRF_UARTE_INT_TXSTOPPED_MASK);
+	}
 
 	irq_unlock(key);
+
+	if (already_enabled) {
+		pm_device_runtime_put(dev);
+	}
 }
 
 /** Interrupt driven transfer disabling function */
 static void uarte_nrfx_irq_tx_disable(const struct device *dev)
 {
 	struct uarte_nrfx_data *data = dev->data;
-	/* TX IRQ will be disabled after current transmission is finished */
-	data->int_driven->disable_tx_irq = true;
-	data->int_driven->tx_irq_enabled = false;
+	if (data->int_driven->tx_irq_enabled) {
+		/* TX IRQ will be disabled after current transmission is finished */
+		data->int_driven->disable_tx_irq = true;
+		data->int_driven->tx_irq_enabled = false;
+	}
 }
 
 /** Interrupt driven transfer ready function */
@@ -2888,15 +2896,23 @@ static void uarte_nrfx_irq_rx_enable(const struct device *dev)
 {
 	NRF_UARTE_Type *uarte = get_uarte_instance(dev);
 
-	nrf_uarte_int_enable(uarte, NRF_UARTE_INT_ENDRX_MASK);
+	if (!nrf_uarte_int_enable_check(uarte, NRF_UARTE_INT_ENDRX_MASK)) {
+		pm_device_runtime_get(dev);
+
+		nrf_uarte_int_enable(uarte, NRF_UARTE_INT_ENDRX_MASK);
+	}
 }
 
 /** Interrupt driven receiver disabling function */
 static void uarte_nrfx_irq_rx_disable(const struct device *dev)
 {
 	NRF_UARTE_Type *uarte = get_uarte_instance(dev);
 
-	nrf_uarte_int_disable(uarte, NRF_UARTE_INT_ENDRX_MASK);
+	if (nrf_uarte_int_enable_check(uarte, NRF_UARTE_INT_ENDRX_MASK)) {
+		pm_device_runtime_put_async(dev, K_NO_WAIT);
+
+		nrf_uarte_int_disable(uarte, NRF_UARTE_INT_ENDRX_MASK);
+	}
 }
 
 /** Interrupt driven error enabling function */