expose FIFO pressure level in header

can-halal.c

@@ -221,12 +221,8 @@ void HAL_FDCAN_RxFifo0Callback(FDCAN_HandleTypeDef *handle,
   ftcan_msg_received_cb(header.Identifier, datalen, data);
 }
 
-HAL_StatusTypeDef ftcan_get_tx_queue_length(uint32_t *length) {
-  if (length == NULL) {
-    return HAL_ERROR;
-  }
-  *length = HAL_FDCAN_GetTxFifoFreeLevel(hcan);
-  return HAL_OK;
+uint32_t ftcan_get_tx_queue_length() {
+  return HAL_FDCAN_GetTxFifoFreeLevel(hcan);
 }
 
 #if FTCAN_NUM_TX_BUFFERS

can-halal.h

@@ -53,6 +53,8 @@ HAL_StatusTypeDef ftcan_transmit(uint16_t id, const uint8_t *data,
 
 HAL_StatusTypeDef ftcan_add_filter(uint16_t id, uint16_t mask);
 
+uint32_t ftcan_get_tx_queue_length();
+
 /**
  * Define this function to be notified of incoming CAN messages
  */