Added RTS/CTS flow control

Currently implemented only for LPC1768. On this platform, when hardware
flow control is not directly supported, it will be emulated.
Also added "not_implemented.c" as a placeholder for various HAL functions
that might not be implemented on all platforms (in this particular case,
serial_set_flow_control). These are weak implementations that default to a
"not implemented" error message.

Author: Bogdan Marinescu

libraries/mbed/api/SerialBase.h

@@ -51,6 +51,13 @@ class SerialBase {
         TxIrq
     };
 
+    enum Flow {
+        Disabled = 0,
+        RTS,
+        CTS,
+        RTSCTS
+    };
+
     /** Set the transmission format used by the serial port
      *
      *  @param bits The number of bits in a word (5-8; default = 8)
@@ -99,6 +106,14 @@ class SerialBase {
     /** Generate a break condition on the serial line
      */
     void send_break();
+    
+    /** Set the flow control type on the serial port
+     *
+     *  @param type the flow control type (Disabled, RTS, CTS, RTSCTS)     
+     *  @param flow1 the first flow control pin (RTS for RTS or RTSCTS, CTS for CTS)
+     *  @param flow2 the second flow control pin (CTS for RTSCTS)
+     */
+    void set_flow_control(Flow type, PinName flow1=NC, PinName flow2=NC);
 
     static void _irq_handler(uint32_t id, SerialIrq irq_type);
 

libraries/mbed/common/SerialBase.cpp

@@ -81,6 +81,26 @@ void SerialBase::send_break() {
   serial_break_clear(&_serial);
 }
 
+void SerialBase::set_flow_control(Flow type, PinName flow1, PinName flow2) {
+    FlowControl flow_type = (FlowControl)type;
+    switch(type) {
+        case RTS:
+            serial_set_flow_control(&_serial, flow_type, flow1, NC);
+            break;
+            
+        case CTS:
+            serial_set_flow_control(&_serial, flow_type, NC, flow1);
+            break;
+            
+        case RTSCTS:
+            serial_set_flow_control(&_serial, flow_type, flow1, flow2);
+            break;
+            
+        default:
+            break;
+    }
+}
+
 } // namespace mbed
 
 #endif

libraries/mbed/common/not_implemented.c

@@ -0,0 +1,28 @@
+/* mbed Microcontroller Library
+ * Copyright (c) 2006-2013 ARM Limited
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+// Default versions of various HAL functions that might not be implemented for some platforms.
+  
+#include "toolchain.h"
+#include "serial_api.h"
+#include "error.h"
+
+WEAK void serial_set_flow_control(serial_t *obj, FlowControl type, PinName rxflow, PinName txflow);
+WEAK void serial_set_flow_control(serial_t *obj, FlowControl type, PinName rxflow, PinName txflow) {
+    if (FlowControlNone != type)
+        error("hardware flow control not implemented on this platform");
+}
+

libraries/mbed/common/pinmap_common.c

@@ -44,17 +44,22 @@ uint32_t pinmap_merge(uint32_t a, uint32_t b) {
     return (uint32_t)NC;
 }
 
-uint32_t pinmap_peripheral(PinName pin, const PinMap* map) {
-    if (pin == (PinName)NC)
-        return (uint32_t)NC;
-
+uint32_t pinmap_find_peripheral(PinName pin, const PinMap* map) {
     while (map->pin != NC) {
         if (map->pin == pin)
             return map->peripheral;
         map++;
     }
-
-    // no mapping available
-    error("pinmap not found for peripheral");
     return (uint32_t)NC;
 }
+
+uint32_t pinmap_peripheral(PinName pin, const PinMap* map) {
+    uint32_t peripheral = (uint32_t)NC;
+
+    if (pin == (PinName)NC)
+        return (uint32_t)NC;
+    peripheral = pinmap_find_peripheral(pin, map);
+    if ((uint32_t)NC == peripheral) // no mapping available
+        error("pinmap not found for peripheral");
+    return peripheral;
+}

libraries/mbed/hal/pinmap.h

@@ -34,6 +34,7 @@ void pin_mode    (PinName pin, PinMode mode);
 uint32_t pinmap_peripheral(PinName pin, const PinMap* map);
 uint32_t pinmap_merge     (uint32_t a, uint32_t b);
 void     pinmap_pinout    (PinName pin, const PinMap *map);
+uint32_t pinmap_find_peripheral(PinName pin, const PinMap* map);
 
 #ifdef __cplusplus
 }

libraries/mbed/hal/serial_api.h

@@ -37,6 +37,13 @@ typedef enum {
     TxIrq
 } SerialIrq;
 
+typedef enum {
+    FlowControlNone,
+    FlowControlRTS,
+    FlowControlCTS,
+    FlowControlRTSCTS
+} FlowControl;
+
 typedef void (*uart_irq_handler)(uint32_t id, SerialIrq event);
 
 typedef struct serial_s serial_t;
@@ -60,6 +67,8 @@ void serial_break_clear(serial_t *obj);
 
 void serial_pinout_tx(PinName tx);
 
+void serial_set_flow_control(serial_t *obj, FlowControl type, PinName rxflow, PinName txflow);
+
 #ifdef __cplusplus
 }
 #endif

libraries/mbed/targets/hal/TARGET_NXP/TARGET_LPC176X/objects.h

@@ -20,6 +20,7 @@
 #include "PortNames.h"
 #include "PeripheralNames.h"
 #include "PinNames.h"
+#include "gpio_object.h"
 
 #ifdef __cplusplus
 extern "C" {
@@ -47,7 +48,6 @@ struct pwmout_s {
 struct serial_s {
     LPC_UART_TypeDef *uart;
     int index;
-    uint8_t count;
 };
 
 struct analogin_s {
@@ -71,8 +71,6 @@ struct spi_s {
     LPC_SSP_TypeDef *spi;
 };
 
-#include "gpio_object.h"
-
 #ifdef __cplusplus
 }
 #endif

libraries/mbed/targets/hal/TARGET_NXP/TARGET_LPC176X/serial_api.c

@@ -21,6 +21,7 @@
 #include "cmsis.h"
 #include "pinmap.h"
 #include "error.h"
+#include "gpio_api.h"
 
 /******************************************************************************
  * INITIALIZATION
@@ -51,12 +52,35 @@ static const PinMap PinMap_UART_RX[] = {
     {NC   , NC    , 0}
 };
 
+static const PinMap PinMap_UART_RTS[] = {
+    {P0_22, UART_1, 1},
+    {P2_7,  UART_1, 2},
+    {NC,    NC,     0}
+};
+
+static const PinMap PinMap_UART_CTS[] = {
+    {P0_17, UART_1, 1},
+    {P2_2,  UART_1, 2},
+    {NC,    NC,     0}
+};
+
+#define UART_MCR_RTSEN_MASK     (1 << 6)
+#define UART_MCR_CTSEN_MASK     (1 << 7)
+#define UART_MCR_FLOWCTRL_MASK  (UART_MCR_RTSEN_MASK | UART_MCR_CTSEN_MASK)
+
 static uint32_t serial_irq_ids[UART_NUM] = {0};
 static uart_irq_handler irq_handler;
 
 int stdio_uart_inited = 0;
 serial_t stdio_uart;
 
+struct serial_global_data_s {
+    gpio_t sw_rts, sw_cts;
+    uint8_t count, initialized, irq_set_flow, irq_set_api;
+};
+
+static struct serial_global_data_s uart_data[UART_NUM];
+
 void serial_init(serial_t *obj, PinName tx, PinName rx) {
     int is_stdio_uart = 0;
 
@@ -106,7 +130,11 @@ void serial_init(serial_t *obj, PinName tx, PinName rx) {
         case UART_2: obj->index = 2; break;
         case UART_3: obj->index = 3; break;
     }
-    obj->count = 0;
+    if (!uart_data[obj->index].initialized) {
+        uart_data[obj->index].sw_rts.pin = NC;
+        uart_data[obj->index].sw_cts.pin = NC;
+        uart_data[obj->index].initialized = 1;
+    }
 
     is_stdio_uart = (uart == STDIO_UART) ? (1) : (0);
 
@@ -234,7 +262,9 @@ static inline void uart_irq(uint32_t iir, uint32_t index) {
         case 2: irq_type = RxIrq; break;
         default: return;
     }
-    
+
+    if ((RxIrq == irq_type) && (uart_data[index].sw_rts.pin != NC))
+        gpio_write(&uart_data[index].sw_rts, 1);
     if (serial_irq_ids[index] != 0)
         irq_handler(serial_irq_ids[index], irq_type);
 }
@@ -249,7 +279,7 @@ void serial_irq_handler(serial_t *obj, uart_irq_handler handler, uint32_t id) {
     serial_irq_ids[obj->index] = id;
 }
 
-void serial_irq_set(serial_t *obj, SerialIrq irq, uint32_t enable) {
+static void serial_irq_set_internal(serial_t *obj, SerialIrq irq, uint32_t enable) {
     IRQn_Type irq_n = (IRQn_Type)0;
     uint32_t vector = 0;
     switch ((int)obj->uart) {
@@ -263,7 +293,7 @@ void serial_irq_set(serial_t *obj, SerialIrq irq, uint32_t enable) {
         obj->uart->IER |= 1 << irq;
         NVIC_SetVector(irq_n, vector);
         NVIC_EnableIRQ(irq_n);
-    } else { // disable
+    } else if (uart_data[obj->index].irq_set_api + uart_data[obj->index].irq_set_flow == 0) { // disable
         int all_disabled = 0;
         SerialIrq other_irq = (irq == RxIrq) ? (TxIrq) : (RxIrq);
         obj->uart->IER &= ~(1 << irq);
@@ -273,18 +303,30 @@ void serial_irq_set(serial_t *obj, SerialIrq irq, uint32_t enable) {
     }
 }
 
+void serial_irq_set(serial_t *obj, SerialIrq irq, uint32_t enable) {
+    uart_data[obj->index].irq_set_api = enable;
+    serial_irq_set_internal(obj, irq, enable);
+}
+
+static void serial_flow_irq_set(serial_t *obj, SerialIrq irq, uint32_t enable) {
+    uart_data[obj->index].irq_set_flow = enable;
+    serial_irq_set_internal(obj, irq, enable);
+}
+
 /******************************************************************************
  * READ/WRITE
  ******************************************************************************/
 int serial_getc(serial_t *obj) {
     while (!serial_readable(obj));
+    if (NC != uart_data[obj->index].sw_rts.pin)
+        gpio_write(&uart_data[obj->index].sw_rts, 0);
     return obj->uart->RBR;
 }
 
 void serial_putc(serial_t *obj, int c) {
     while (!serial_writable(obj));
     obj->uart->THR = c;
-    obj->count++;
+    uart_data[obj->index].count++;
 }
 
 int serial_readable(serial_t *obj) {
@@ -293,11 +335,14 @@ int serial_readable(serial_t *obj) {
 
 int serial_writable(serial_t *obj) {
     int isWritable = 1;
-    if (obj->uart->LSR & 0x20)
-        obj->count = 0;
-    else if (obj->count >= 16)
-        isWritable = 0;
-        
+    if (NC != uart_data[obj->index].sw_cts.pin)
+        isWritable = gpio_read(&uart_data[obj->index].sw_cts) == 0;
+    if (isWritable) {
+        if (obj->uart->LSR & 0x20)
+            uart_data[obj->index].count = 0;
+        else if (uart_data[obj->index].count >= 16)
+            isWritable = 0;
+    }
     return isWritable;
 }
 
@@ -320,3 +365,47 @@ void serial_break_clear(serial_t *obj) {
     obj->uart->LCR &= ~(1 << 6);
 }
 
+void serial_set_flow_control(serial_t *obj, FlowControl type, PinName rxflow, PinName txflow) {
+    // Only UART1 has hardware flow control on LPC176x
+    LPC_UART1_TypeDef *uart1 = (uint32_t)obj->uart == (uint32_t)LPC_UART1 ? LPC_UART1 : NULL;
+    int index = obj->index;
+
+    // First, disable flow control completely
+    if (uart1)
+        uart1->MCR = uart1->MCR & ~UART_MCR_FLOWCTRL_MASK;
+    serial_flow_irq_set(obj, RxIrq, 0);
+    uart_data[index].sw_rts.pin = uart_data[index].sw_cts.pin = NC;
+    if (FlowControlNone == type)
+        return;
+    // Check type(s) of flow control to use
+    UARTName uart_rts = (UARTName)pinmap_find_peripheral(rxflow, PinMap_UART_RTS);
+    UARTName uart_cts = (UARTName)pinmap_find_peripheral(txflow, PinMap_UART_CTS);
+    if (((FlowControlCTS == type) || (FlowControlRTSCTS == type)) && (NC != txflow)) {
+        // Can this be enabled in hardware?
+        if ((UART_1 == uart_cts) && (NULL != uart1)) {
+            // Enable auto-CTS mode
+            uart1->MCR |= UART_MCR_CTSEN_MASK;
+        } else {
+            // Can't enable in hardware, use software emulation
+            gpio_init(&uart_data[index].sw_cts, txflow, PIN_INPUT);
+        }
+    }
+    if (((FlowControlRTS == type) || (FlowControlRTSCTS == type)) && (NC != rxflow)) {
+        // Enable FIFOs, trigger level of 1 char on RX FIFO
+        obj->uart->FCR = 1 << 0  // FIFO Enable - 0 = Disables, 1 = Enabled
+                       | 1 << 1  // Rx Fifo Reset
+                       | 1 << 2  // Tx Fifo Reset
+                       | 0 << 6; // Rx irq trigger level - 0 = 1 char, 1 = 4 chars, 2 = 8 chars, 3 = 14 chars
+         // Can this be enabled in hardware?
+        if ((UART_1 == uart_rts) && (NULL != uart1)) {
+            // Enable auto-RTS mode
+            uart1->MCR |= UART_MCR_RTSEN_MASK;
+        } else { // can't enable in hardware, use software emulation
+            gpio_init(&uart_data[index].sw_rts, rxflow, PIN_OUTPUT);
+            gpio_write(&uart_data[index].sw_rts, 0);
+            // Enable RX interrupt
+            serial_flow_irq_set(obj, RxIrq, 1);
+        }
+    }
+}
+