modem: backend: uart: Implement transmit idle event

Make async and interrupt driven UART backends notify transmit
idle when transmit is idle.

Signed-off-by: Bjarki Arge Andreasen <[email protected]>

Author: bjarki-andreasen

include/zephyr/modem/backend/uart.h

@@ -43,6 +43,7 @@ struct modem_backend_uart {
 	const struct device *uart;
 	struct modem_pipe pipe;
 	struct k_work receive_ready_work;
+	struct k_work transmit_idle_work;
 
 	union {
 		struct modem_backend_uart_isr isr;

subsys/modem/backends/modem_backend_uart.c

@@ -22,6 +22,14 @@ static void modem_backend_uart_receive_ready_handler(struct k_work *item)
 	modem_pipe_notify_receive_ready(&backend->pipe);
 }
 
+static void modem_backend_uart_transmit_idle_handler(struct k_work *item)
+{
+	struct modem_backend_uart *backend =
+		CONTAINER_OF(item, struct modem_backend_uart, transmit_idle_work);
+
+	modem_pipe_notify_transmit_idle(&backend->pipe);
+}
+
 struct modem_pipe *modem_backend_uart_init(struct modem_backend_uart *backend,
 					   const struct modem_backend_uart_config *config)
 {
@@ -35,6 +43,7 @@ struct modem_pipe *modem_backend_uart_init(struct modem_backend_uart *backend,
 	memset(backend, 0x00, sizeof(*backend));
 	backend->uart = config->uart;
 	k_work_init(&backend->receive_ready_work, modem_backend_uart_receive_ready_handler);
+	k_work_init(&backend->transmit_idle_work, modem_backend_uart_transmit_idle_handler);
 
 #ifdef CONFIG_MODEM_BACKEND_UART_ASYNC
 	if (modem_backend_uart_async_is_supported(backend)) {

subsys/modem/backends/modem_backend_uart_async.c

@@ -44,13 +44,15 @@ static void modem_backend_uart_async_event_handler(const struct device *dev,
 	case UART_TX_DONE:
 		atomic_clear_bit(&backend->async.state,
 				 MODEM_BACKEND_UART_ASYNC_STATE_TRANSMITTING_BIT);
+		k_work_submit(&backend->transmit_idle_work);
 
 		break;
 
 	case UART_TX_ABORTED:
 		LOG_WRN("Transmit aborted");
 		atomic_clear_bit(&backend->async.state,
 				 MODEM_BACKEND_UART_ASYNC_STATE_TRANSMITTING_BIT);
+		k_work_submit(&backend->transmit_idle_work);
 
 		break;
 

subsys/modem/backends/modem_backend_uart_isr.c

@@ -56,6 +56,7 @@ static void modem_backend_uart_isr_irq_handler_transmit_ready(struct modem_backe
 
 	if (ring_buf_is_empty(&backend->isr.transmit_rb) == true) {
 		uart_irq_tx_disable(backend->uart);
+		k_work_submit(&backend->transmit_idle_work);
 		return;
 	}