uart: update C API

Signed-off-by: Thomas Ingleby <thomas.c.ingleby@intel.com>

api/mraa/uart.h

@@ -55,16 +55,67 @@ typedef struct _uart* mraa_uart_context;
  */
 mraa_uart_context mraa_uart_init(int uart);
 
-mraa_uart_context mraa_uart_init_raw(int uart);
+/**
+ * Initialise a raw uart_context. No board setup.
+ *
+ * @param path for example "/dev/ttyS0"
+ * @return uart context or NULL
+ */
+mraa_uart_context mraa_uart_init_raw(char* path);
 
-mraa_result_t mraa_uart_flush(mraa_uart_context);
+/**
+ * Flush the outbound data.
+ * Blocks until complete.
+ *
+ * @param dev The UART context
+ * @return Result of operation
+ */
+mraa_result_t mraa_uart_flush(mraa_uart_context dev);
 
+/**
+ * Set the baudrate.
+ * Takes an int and will attempt to decide what baudrate  is
+ * to be used on the UART hardware.
+ *
+ * @param dev The UART context
+ * @param baud unsigned int of baudrate i.e. 9600
+ * @return Result of operation
+ */
 mraa_result_t mraa_uart_set_baudrate(mraa_uart_context dev, unsigned int baud);
 
+/**
+ * Set the transfer mode
+ * For example setting the mode to 8N1 would be
+ * "mraa_uart_set_mode(dev, 8,MRAA_UART_PARITY_NONE , 1)"
+ *
+ * @param dev The UART context
+ * @param bytesize data bits
+ * @param parity Parity bit setting
+ * @param stopbits stop bits
+ * @return Result of operation
+ */
 mraa_result_t mraa_uart_set_mode(mraa_uart_context dev, int bytesize, mraa_uart_parity_t parity, int stopbits);
 
+/**
+ * Set the flowcontrol
+ *
+ * @param dev The UART context
+ * @param xonxoff XON/XOFF Software flow control.
+ * @param rtscts RTS/CTS out of band hardware flow control
+ * @return Result of operation
+ */
 mraa_result_t mraa_uart_set_flowcontrol(mraa_uart_context dev, mraa_boolean_t xonxoff, mraa_boolean_t rtscts);
 
+/**
+ * Set the timeout for read and write operations
+ * <= 0 will disable that timeout
+ *
+ * @param dev The UART context
+ * @param read read timeout
+ * @param write write timeout
+ * @param interchar inbetween char timeout
+ * @return Result of operation
+ */
 mraa_result_t mraa_uart_set_timeout(mraa_uart_context dev, int read, int write, int interchar);
 
 /**
@@ -89,20 +140,20 @@ mraa_result_t mraa_uart_stop(mraa_uart_context dev);
  *
  * @param dev uart context
  * @param buf buffer pointer
- * @param len maximum size of buffer
+ * @param length maximum size of buffer
  * @return the number of bytes read, or -1 if an error occurred
  */
-int mraa_uart_read(mraa_uart_context dev, char* buf, size_t len);
+int mraa_uart_read(mraa_uart_context dev, char* buf, size_t length);
 
 /**
  * Write bytes in buffer to a device
  *
  * @param dev uart context
  * @param buf buffer pointer
- * @param len maximum size of buffer
+ * @param length maximum size of buffer
  * @return the number of bytes written, or -1 if an error occurred
  */
-int mraa_uart_write(mraa_uart_context dev, char* buf, size_t len);
+int mraa_uart_write(mraa_uart_context dev, char* buf, size_t length);
 
 /**
  * Check to see if data is available on the device for reading

api/mraa/uart.hpp

@@ -1,6 +1,7 @@
 /*
  * Author: Brendan Le Foll <brendan.le.foll@intel.com>
  * Contributions: Jon Trulson <jtrulson@ics.com>
+ * Contributions: Thomas Ingleby <thomas.c.ingleby@intel.com>
  * Copyright (c) 2014 - 2015 Intel Corporation.
  *
  * Permission is hereby granted, free of charge, to any person obtaining
@@ -27,6 +28,7 @@
 
 #include "uart.h"
 #include <stdexcept>
+#include <cstring>
 
 namespace mraa
 {
@@ -53,6 +55,24 @@ class Uart
             throw std::invalid_argument("Error initialising UART");
         }
     }
+
+    /**
+     * Uart Constructor, takes a string to the path of the serial
+     * interface that is needed.
+     *
+     * @param uart the index of the uart set to use
+     */
+    Uart(std::string path)
+    {
+        char *p = new char[path.length() + 1];
+        std::strcpy(p, path.c_str());
+        m_uart = mraa_uart_init_raw(p);
+
+        if (m_uart == NULL) {
+            throw std::invalid_argument("Error initialising UART");
+        }
+    }
+
     /**
      * Uart destructor
      */

src/uart/uart.c

@@ -152,7 +152,11 @@ mraa_uart_init(int index)
         }
     }
 
-    mraa_uart_context dev = mraa_uart_init_raw(index);
+    mraa_uart_context dev = mraa_uart_init_raw((char*)plat->uart_dev[index].device_path);
+    if (dev == NULL) {
+        return NULL;
+    }
+    dev->index = index; //Set the board Index.
 
     if (advance_func->uart_init_post != NULL) {
         mraa_result_t ret = advance_func->uart_init_post(dev);
@@ -166,7 +170,7 @@ mraa_uart_init(int index)
 }
 
 mraa_uart_context
-mraa_uart_init_raw(int index)
+mraa_uart_init_raw(char* path)
 {
     mraa_uart_context dev = (mraa_uart_context) malloc(sizeof(struct _uart));
     if (dev == NULL) {
@@ -175,20 +179,18 @@ mraa_uart_init_raw(int index)
     }
     memset(dev, 0, sizeof(struct _uart));
 
-    dev->index = index;
+    dev->index = -1;
     dev->fd = -1;
-    dev->path = (char*) plat->uart_dev[index].device_path;
+    dev->path = path;
 
-    char* devPath = mraa_uart_get_dev_path(dev);
-
-    if (!devPath) {
+    if (!dev->path) {
         syslog(LOG_ERR, "uart: device path undefined, open failed");
         free(dev);
         return NULL;
     }
 
     // now open the device
-    if ((dev->fd = open(devPath, O_RDWR)) == -1) {
+    if ((dev->fd = open(dev->path, O_RDWR)) == -1) {
         syslog(LOG_ERR, "uart: open() failed");
         free(dev);
         return NULL;