serial: add CTS/RTS flowcontrol.

bsp/stm32/libraries/HAL_Drivers/drv_usart.c

@@ -107,10 +107,22 @@ static rt_err_t stm32_configure(struct rt_serial_device *serial, struct serial_c
     uart = rt_container_of(serial, struct stm32_uart, serial);
     uart->handle.Instance          = uart->config->Instance;
     uart->handle.Init.BaudRate     = cfg->baud_rate;
-    uart->handle.Init.HwFlowCtl    = UART_HWCONTROL_NONE;
     uart->handle.Init.Mode         = UART_MODE_TX_RX;
     uart->handle.Init.OverSampling = UART_OVERSAMPLING_16;
 
+    switch (cfg->flowcontrol)
+    {
+    case RT_SERIAL_FLOWCONTROL_NONE:
+        uart->handle.Init.HwFlowCtl = UART_HWCONTROL_NONE;
+        break;
+    case RT_SERIAL_FLOWCONTROL_CTSRTS:
+        uart->handle.Init.HwFlowCtl = UART_HWCONTROL_RTS_CTS;
+        break;
+    default:
+        uart->handle.Init.HwFlowCtl = UART_HWCONTROL_NONE;
+        break;
+    }
+
     switch (cfg->data_bits)
     {
     case DATA_BITS_8:

components/drivers/include/drivers/serial.h

@@ -77,6 +77,9 @@
 #define RT_SERIAL_TX_DATAQUEUE_SIZE     2048
 #define RT_SERIAL_TX_DATAQUEUE_LWM      30
 
+#define RT_SERIAL_FLOWCONTROL_CTSRTS     1
+#define RT_SERIAL_FLOWCONTROL_NONE       0
+
 /* Default config for serial_configure structure */
 #define RT_SERIAL_CONFIG_DEFAULT           \
 {                                          \
@@ -87,6 +90,7 @@
     BIT_ORDER_LSB,    /* LSB first sent */ \
     NRZ_NORMAL,       /* Normal mode */    \
     RT_SERIAL_RB_BUFSZ, /* Buffer size */  \
+    RT_SERIAL_FLOWCONTROL_NONE, /* Off flowcontrol */ \
     0                                      \
 }
 
@@ -100,7 +104,8 @@ struct serial_configure
     rt_uint32_t bit_order               :1;
     rt_uint32_t invert                  :1;
     rt_uint32_t bufsz                   :16;
-    rt_uint32_t reserved                :6;
+    rt_uint32_t flowcontrol             :1;
+    rt_uint32_t reserved                :5;
 };
 
 /*