[USB Serial/JTAG] [VFS] add flag if driver has ever received bytes

components/driver/include/driver/usb_serial_jtag.h

@@ -72,6 +72,16 @@ int usb_serial_jtag_read_bytes(void* buf, uint32_t length, TickType_t ticks_to_w
  */
 int usb_serial_jtag_write_bytes(const void* src, size_t size, TickType_t ticks_to_wait);
 
+
+/**
+ * @brief Returns true if the USB Serial/JTAG Controller driver has ever
+ * received any bytes over its serial port since the driver was installed.
+ *
+ * This can be used as a simple way to determine that a serial
+ * console has definitely been attached at some point
+ */
+bool usb_serial_jtag_driver_has_received_bytes();
+
 /**
  * @brief Uninstall USB-SERIAL-JTAG driver.
  *

components/driver/usb_serial_jtag.c

@@ -28,6 +28,7 @@ typedef struct{
     RingbufHandle_t rx_ring_buf;        /*!< RX ring buffer handler */
     uint32_t rx_buf_size;               /*!< TX buffer size */
     uint8_t rx_data_buf[64];            /*!< Data buffer to stash FIFO data */
+    bool rx_has_received_bytes;         /*!< True if the driver has ever received bytes since install */
 
     // TX parameters
     uint32_t tx_buf_size;               /*!< TX buffer size */
@@ -73,6 +74,7 @@ static void usb_serial_jtag_isr_handler_default(void *arg) {
     if (usbjtag_intr_status & USB_SERIAL_JTAG_INTR_SERIAL_OUT_RECV_PKT) {
         // read rx buffer(max length is 64), and send avaliable data to ringbuffer.
         // Ensure the rx buffer size is larger than RX_MAX_SIZE.
+        p_usb_serial_jtag_obj->rx_has_received_bytes = true;
         usb_serial_jtag_ll_clr_intsts_mask(USB_SERIAL_JTAG_INTR_SERIAL_OUT_RECV_PKT);
         uint32_t rx_fifo_len = usb_serial_jtag_ll_read_rxfifo(p_usb_serial_jtag_obj->rx_data_buf, USB_SER_JTAG_RX_MAX_SIZE);
         xRingbufferSendFromISR(p_usb_serial_jtag_obj->rx_ring_buf, p_usb_serial_jtag_obj->rx_data_buf, rx_fifo_len, &xTaskWoken);
@@ -169,6 +171,14 @@ int usb_serial_jtag_write_bytes(const void* src, size_t size, TickType_t ticks_t
     return size;
 }
 
+bool usb_serial_jtag_driver_has_received_bytes()
+{
+    if (p_usb_serial_jtag_obj != NULL){
+        return p_usb_serial_jtag_obj->rx_has_received_bytes;
+    }
+    return false;
+}
+
 esp_err_t usb_serial_jtag_driver_uninstall(void)
 {
     if(p_usb_serial_jtag_obj == NULL) {