uart: add uart device open and close functionality

Signed-off-by: Jon Trulson <jtrulson@ics.com>
Signed-off-by: Brendan Le Foll <brendan.le.foll@intel.com>

api/mraa/uart.h

@@ -1,5 +1,6 @@
 /*
  * Author: Thomas Ingleby <thomas.c.ingleby@intel.com>
+ * Contributions: Jon Trulson <jtrulson@ics.com>
  * Copyright (c) 2014 Intel Corporation.
  *
  * Permission is hereby granted, free of charge, to any person obtaining
@@ -41,6 +42,15 @@ extern "C" {
 
 #include <stdio.h>
 #include <fcntl.h>
+#include <stdlib.h>
+#include <unistd.h>
+#include <string.h>
+#include <errno.h>
+#include <termios.h>
+#include <sys/time.h>
+#include <sys/select.h>
+#include <sys/types.h>
+#include <sys/stat.h>
 
 #include "common.h"
 
@@ -63,6 +73,26 @@ mraa_uart_context mraa_uart_init(int uart);
  */
 char* mraa_uart_get_dev_path(mraa_uart_context dev);
 
+/**
+ * Open the TTY device associated with a UART context, and set up the
+ * terminal modes and baud rate.  The TTY is setup for a 'raw'
+ * mode. 81N, no echo or special character handling, such as flow
+ * control or line editing semantics.
+ *
+ * @param dev uart context
+ * @param baud desired baud rate
+ * @return mraa_result_t
+ */
+mraa_result_t mraa_uart_open_dev(mraa_uart_context dev, speed_t baud);
+
+/**
+ * Close a device previously opened with mraa_uart_open_dev().
+ *
+ * @param dev uart context
+ * @return mraa_result_t
+ */
+mraa_result_t mraa_uart_close_dev(mraa_uart_context dev);
+
 #ifdef __cplusplus
 }
 #endif

api/mraa/uart.hpp

@@ -1,5 +1,6 @@
 /*
  * Author: Brendan Le Foll <brendan.le.foll@intel.com>
+ * Contributions: Jon Trulson <jtrulson@ics.com>
  * Copyright (c) 2014 Intel Corporation.
  *
  * Permission is hereby granted, free of charge, to any person obtaining
@@ -57,6 +58,7 @@ class Uart
      */
     ~Uart()
     {
+        closeDevice();
         return;
     }
 
@@ -73,6 +75,33 @@ class Uart
         return ret_val;
     }
 
+    /**
+     * Open the TTY device associated with a UART context, and set up the
+     * terminal modes and baud rate.  The TTY is setup for a 'raw'
+     * mode.  81N, no echo or special character handling, such as flow
+     * control or line editing semantics.
+     *
+     * @param baud desired baud rate
+     * @return mraa_result_t
+     */
+    mraa_result_t
+    openDevice(speed_t baud)
+    {
+        return mraa_uart_open_dev(m_uart, baud);
+    }
+
+    /**
+     * Close a device previously opened with mraa_uart_open_dev().
+     *
+     * @param dev uart context
+     * @return mraa_result_t
+     */
+    mraa_result_t
+    closeDevice()
+    {
+        return mraa_uart_close_dev(m_uart);
+    }
+
   private:
     mraa_uart_context m_uart;
 };

src/uart/uart.c

@@ -1,5 +1,6 @@
 /*
  * Author: Thomas Ingleby <thomas.c.ingleby@intel.com>
+ * Contributions: Jon Trulson <jtrulson@ics.com>
  * Copyright (c) 2014 Intel Corporation.
  *
  * Permission is hereby granted, free of charge, to any person obtaining
@@ -109,3 +110,65 @@ mraa_uart_get_dev_path(mraa_uart_context dev)
     }
     return dev->path;
 }
+
+mraa_result_t
+mraa_uart_open_dev(mraa_uart_context dev, speed_t baud)
+{
+    if (!dev) {
+        syslog(LOG_ERR, "uart: open: context is NULL");
+        return MRAA_ERROR_INVALID_HANDLE;
+    }
+
+    char *devPath = mraa_uart_get_dev_path(dev);
+
+    if (!devPath) {
+        syslog(LOG_ERR, "uart: device path undefined, open failed");
+        return MRAA_ERROR_UNSPECIFIED;
+    }
+
+    // now open the device
+    if ( (dev->fd = open(devPath, O_RDWR)) == -1) {
+        syslog(LOG_ERR, "uart: open() failed");
+        return MRAA_ERROR_UNSPECIFIED;
+    }
+
+    // now setup the tty and the selected baud rate
+
+    struct termios termio;
+
+    // get current modes
+    tcgetattr(dev->fd, &termio);
+
+    // setup for a 'raw' mode.  81N, no echo or special character
+    // handling, such as flow control or line editing semantics.
+    cfmakeraw(&termio);
+
+    // set our baud rates
+    cfsetispeed(&termio, baud);
+    cfsetospeed(&termio, baud);
+
+    // make it so
+    if (tcsetattr(dev->fd, TCSAFLUSH, &termio) < 0) {
+        syslog(LOG_ERR, "uart: tcsetattr() failed");
+        return MRAA_ERROR_UNSPECIFIED;
+    }
+
+    return MRAA_SUCCESS;
+}
+
+mraa_result_t
+mraa_uart_close_dev(mraa_uart_context dev)
+{
+    if (!dev) {
+        syslog(LOG_ERR, "uart: close: context is NULL");
+        return MRAA_ERROR_INVALID_HANDLE;
+    }
+
+    // just close the device and reset our fd.
+    if (dev->fd >= 0) {
+        close(dev->fd);
+    }
+
+    dev->fd = -1;
+    return MRAA_SUCCESS;
+}