[NRF_5] add configuration for serial flow control

Author: ytsuboi

hal/targets.json

@@ -1538,6 +1538,9 @@
         "macros_add": ["TARGET_NRF_32MHZ_XTAL"],
         "progen": {"target": "ty51822r3"},
         "device_has": ["ANALOGIN", "ERROR_PATTERN", "I2C", "I2C_ASYNCH", "INTERRUPTIN", "LOWPOWERTIMER", "PORTIN", "PORTINOUT", "PORTOUT", "PWMOUT", "RTC", "SERIAL", "SERIAL_ASYNCH", "SLEEP", "SPI", "SPI_ASYNCH", "SPISLAVE"],
+        "overrides": {
+            "serial_fc": "WITHOUT_FC"
+        },
         "detect_code": ["1019"],
         "release_versions": ["2", "5"]
     },
@@ -1887,6 +1890,11 @@
             "lf_clock_src": {
                 "value": "NRF_LF_SRC_XTAL",
                 "macro_name": "MBED_CONF_NORDIC_NRF_LF_CLOCK_SRC"
+            },
+            "serial_fc": {
+                "help": "Choose serial with flow control or without",
+                "value": "WITH_FC",
+                "macro_name": "MBED_CONF_NORDIC_NRF_SERIAL_FC"
             }
         }
     },

hal/targets/hal/TARGET_NORDIC/TARGET_NRF5/serial_api.c

@@ -62,6 +62,15 @@
 #define UART_DEFAULT_CTS        UART0_CONFIG_PSEL_CTS
 #define UART_DEFAULT_RTS        UART0_CONFIG_PSEL_RTS
 
+#ifndef MBED_CONF_NORDIC_NRF_SERIAL_FC
+    #define MBED_CONF_NORDIC_NRF_SERIAL_FC (WITH_FC)
+    #warning No configuration for serial flow control. Serial will be used as a default, with flow control.
+#endif
+
+#define WITH_FC    2
+#define WITHOUT_FC 3
+
+
 // Required by "retarget.cpp".
 int stdio_uart_inited = 0;
 serial_t stdio_uart;
@@ -257,9 +266,16 @@ void serial_init(serial_t *obj, PinName tx, PinName rx) {
     else {
         UART_CB.baudrate = UART_DEFAULT_BAUDRATE;
         UART_CB.parity   = UART_DEFAULT_PARITY;
+
+    #if MBED_CONF_NORDIC_NRF_SERIAL_FC == WITH_FC
         UART_CB.hwfc     = UART_DEFAULT_HWFC;
         UART_CB.pselcts  = UART_DEFAULT_CTS;
         UART_CB.pselrts  = UART_DEFAULT_RTS;
+    #elif MBED_CONF_NORDIC_NRF_SERIAL_FC == WITHOUT_FC
+        // Not init UART with HWFC.
+    #else
+        #error Bad flow control configuration. Declare proper source through mbed configuration.
+    #endif
 
         nrf_uart_event_clear(UART_INSTANCE, NRF_UART_EVENT_RXDRDY);
         nrf_uart_event_clear(UART_INSTANCE, NRF_UART_EVENT_TXDRDY);
@@ -639,4 +655,7 @@ void serial_rx_abort_asynch(serial_t *obj)
 
 #endif // DEVICE_SERIAL_ASYNCH
 
+#undef WITH_FC
+#undef WITHOUT_FC
+
 #endif // DEVICE_SERIAL